,transcriber's ,notes ,when italics were used in the original book1 the corresponding text has been surrounded by underscores4 ,subscripted characters have been preceded by and surrounded by 4 ,in some cases1 ditto marks have been replaced by the text they represent4 ,some corrections have been made to the printed text4 ,these are listed in a second transcriber's note at the end of the text4 ,,observations ,,of ,a ,,naturalist ,,in ,,the ,,pacific ,,between #ahif ,,and #ahii ,illustration3 ,image3 ,publisher ,illustration3 ,,na ,,raro 7#b1dbj feet7 from the south-west1 a peak of acid andesite4 ,illustration3 ,,ndrandramea 7#a1hjj feet7 from the south-east1 a peak of acid andesite rising about a thousand feet from its base4 ,frontispiece4 ,,observations ,,of ,a ,,naturalist ,,in ,,the ,,pacific ,,between #ahif ,,and #ahii ,,by ,h4 ,b4 ,,guppy1 ,m4,b41 ,f4,r4,s4,e4 ,,volume ,i ,,vanua ,,levu1 ,,fiji ,a description of its leading ,physical and ,geological characters ,london ,,macmillan ,,and ,,co41 ,,limited ,,new ,,york2 ,,the ,,macmillan ,,company #aijc ,all rights reserved ,,richard ,,clay ,,and ,,sons1 ,,limited4 ,,bread ,,street ,,hill1 ,e4,c41 ,,and ,,bungay1 ,,suffolk4 ,dedication ,,to ,,the ,,fijian ,,people ,,preface ,,during a sojourn in the ,pacific1 which covered a period of rather over a year in ,hawaii 7#ahif-ig71 and of two years and three months in ,fiji 7#ahig-ii71 my attention was mainly confined to the study of plant-distribution and to the examination of the geological structure of ,vanua ,levu4 ,with ,hillebrand's 8,flora of ,hawaii0 always in my hands ,i roamed over the large island of ,hawaii1 ascending the three principal mountains of ,mauna ,kea1 ,mauna ,loa1 and ,hualalai1 and in the case of my second ascent of ,mauna ,loa spending twenty-three days alone on its summit4 ,similarly in ,fiji1 ,seemann's 8,flora ,vitiensis0 was my counsellor and guide in the matter of plants4 ,in ,hawaii ,i was in a land of active sub-aerial volcanoes1 and ,i paid my devotions at all the altars of 8,pele10 their presiding deity4 ,in ,fiji ,i trod upon the surface of submarine volcanoes that emerged ages since from the ocean and still retain their coverings of sea-deposits4 ,both in ,hawaii and ,fiji ,i lived much among the people2 and though my chief interest lay in the comparison of these two types of volcanic islands1 ,i could not but be drawn to the kindly natives whose hospitality ,i so long enjoyed4 ,destiny led me to ,vanua ,levu in the following fashion4 ,with the relief party to take me down from ,mauna ,loa there arrived a well-known ,german naturalist who1 like myself1 had been interested in coral-reef investigations4 ,we discussed this warm topic at an elevation of nearly #ad1jjj feet above the sea1 with the thermometer at #bj ,f4 ,as we sipped our hot coffee and listened to the occasional 8boom0 from the bottom of the great crater1 at the edge of which we were camped1 ,i remarked to my friend that ,i was thinking of spending some months in ,samoa4 ,to this he good-humouredly replied that ,i might leave ,samoa to his countrymen and describe one of the large islands of ,fiji4 ,international rivalry over that group of islands was then rather keen4 ,however1 ,dr4 ,k4 went to ,samoa1 and ,i have now completed this volume on the geology of ,vanua ,levu1 ,fiji4 ,it will not be necessary to lay stress here on the difficulties and hardships connected with the exploration of little known tropical regions4 ,many will be familiar with all that these imply1 where the rainfall ranges from #ajj to #bej inches1 where the forests are dense1 where tracks are few and swollen rivers are numerous1 and where the torrent's bed presents often the only road4 ,the only extensive geological collections made in ,fiji previous to my visit were those of ,kleinschmidt in #ahgf-gh1 which together with a small collection previously made by ,dr4 ,grffe were examined by ,dr4 ,a4 ,wichmann4 ,these rocks were obtained from ,viti ,levu1 ,kandavu1 ,ovalau1 etc41 but not from ,vanua ,levu4 ,dr4 ,wichmann's paper of #ahhb1 descriptive of these collections1 presents us with the results of one of the earliest studies by modern methods of research of the volcanic rocks of the ,pacific ,islands4 ,it is to this investigator that we are indebted for the establishment of the occurrence of plutonic rocks1 such as granites1 gabbros1 diorites1 in ,viti ,levu4 ,although1 as far as ,i can ascertain1 few1 if any1 rocks have been specially described from ,vanua ,levu1 this island was visited by ,dana in #ahdj when attached to the ,united ,states ,exploring ,expedition under ,wilkes4 ,his observations on its geology were published in his volume on the geology of the expedition4 ,although not extensive they are valuable from their reference to his discovery of trachytic and rhyolitic rocks as well as acid pumice-tuffs in the island4 ,it is singular that his observations have apparently been overlooked by all his successors4 ,wichmann with this discovery unknown to him remarked on the seeming absence of quartz-bearing recent eruptive rocks from the ,south ,seas4 ,when the 8,challenger0 ,expedition visited the group in #ahge some geological collections were made which were described by ,prof4 ,renard in the second volume on the 8,physics and ,chemistry0 of the expedition4 ,no collections1 however1 were made in ,vanua ,levu4 ,in #ahgh ,mr4 ,john ,horne1 ,director of the ,botanic ,gardens at ,mauritius1 made some important observations on the geological structure of this island and of other parts of the group1 which he published in his account of the islands given in 8,a ,year in ,fiji40 ,no collections were obtained by him2 but prominence is given to his observations by ,dr4 ,wichmann and others4 ,like ,dana in the case of the acid volcanic rocks1 ,mr4 ,horne has forestalled me in his conclusion that ,vanua ,levu amongst the other larger islands has been formed mainly of the products of submarine eruptions4 ,the visit of ,prof4 ,a4 ,agassiz to ,fiji in #ahig-ih gave a fresh impetus to its geological investigation4 ,we are indebted to him not only for his own extensive memoir on the islands and coral reefs of this group1 but also for the subsequent important explorations of ,mr4 ,e4 ,c4 ,andrews and ,mr4 ,b4 ,sawyer in ,viti ,levu and the ,lau ,islands4 ,these two gentlemen have since published a short paper on the caves of these islands4 ,mr4 ,eakle has described the volcanic rocks collected during the visit of ,prof4 ,agassiz4 ,it is1 however1 noteworthy that1 although the collections were made in ,viti ,levu1 ,kandavu and in many other of the smaller islands1 ,vanua ,levu is not represented4 ,mr4 ,eakle's conclusion that basic andesites and basalts are the characteristic rocks of the region1 the augite-andesites predominating1 would apply to ,vanua ,levu in great part4 ,this island possesses also in fair amount hypersthene-andesites and dacitic or felsitic andesites1 which are very scantily represented in the collections examined by ,mr4 ,eakle4 ,in connection with the quartz-porphyries and trachytic rocks which also occur in ,vanua ,levu1 it should be observed that ,mr4 ,andrews describes a rhyolite from ,suva in ,viti ,levu4 ,unlike ,viti ,levu1 ,vanua ,levu displays but a small development of plutonic rocks4 ,in conclusion it should be pointed out that much remains to be done in the geological exploration of this island1 and that ,i would have spent a third year in this task much to my profit4 ,still ,i hope that a period of two years devoted to its investigation will be regarded as some excuse for a certain over-confidence in the expression of my opinions4 ,to enumerate all those from whom ,i received much kindness in these islands would be a lengthy task4 ,my indebtedness is very great to ,bishop ,vidal1 ,father ,rougier1 and to various other members of the ,roman ,catholic ,mission1 and ,i experienced similar favours at the hands of ,mr4 ,williams and other ,wesleyan ,missionaries in ,vanua ,levu4 ,mr4 ,f4 ,spence and ,mrs4 ,spence showed me great kindness1 and from ,dr4 ,corney ,i received valuable assistance on my arrival in the group4 ,to the planters my debt is equally great1 more especially to ,mr4 ,barratt1 ,mr4 ,dods1 and ,mr4 ,mills4 ,in conclusion ,i would suggest the foundation of a 8,fijian ,society0 for the investigation of the islands1 for the gathering together of all that has been written about the group and its people1 and for the advancement of science4 ,,henry ,,brougham ,,guppy4 ,june1 #aijc4 ,note4--,a type set of my geological collections representing the massive rocks from this island has been kindly accepted by the ,curator of the ,geological ,museum1 ,jermyn ,street4 ,,list ,,of ,,some ,,of ,,the ,,principal ,,authorities ,,quoted ,,in ,,this ,,book ,,dana1 ,j4 ,d41 on the ,geology of ,fiji in vol4 x1 ,geology1 ,united ,states ,exploring ,expedition ,reports1 ,philadelphia1 #ahdi4 ,,kleinschmidt1 ,t41 8,reisen auf den ,viti-,inseln10 ,journal des ,museum ,godeffroy1 heft #ad1 ,hamburg1 #ahgi4 ,,horne1 ,j41 8,a ,year in ,fiji10 ,london1 #ahha4 ,,wichmann1 ,a41 8,ein ,beitrag zur ,petrographie des ,viti-,archipels1 ,mineralogische und ,petrographische1 ,mittheilungen10 band v1 heft #a1 ,wien1 #ahhb4 ,,renard1 ,a41 on andesites from ,kandavu1 8,report on the ,petrology of ,oceanic ,islands10 vol4 ii of 8,physics and ,chemistry10 ,challenger ,expedition1 #ahhi4 ,,agassiz1 ,a41 8,the ,islands and ,coral ,reefs of ,fiji10 ,bulletin1 ,museum of ,comparative ,zoology1 ,harvard ,college1 vol4 xxxiii1 #ahii1 ,cambridge1 ,mass4 ,,eakle1 ,a4 ,s41 8,petrographical ,notes on some rocks from the ,fiji ,islands10 ,proceedings1 ,american ,academy of ,arts and ,sciences1 vol4 xxxiv1 no4 #ba1 ,may1 #ahii4 ,,andrews1 ,e4 ,c41 ,notes on the limestones and general geology of the ,fiji ,islands1 with special reference to the ,lau ,group4 ,based upon surveys made for ,alexander ,agassiz4 ,with a ,preface by ,t4 ,w4 ,edgeworth ,david4 ,bulletin1 ,museum of ,comparative ,zoology1 ,harvard ,college2 vol4 xxxviii1 ,cambridge1 ,mass4 #aijj4 ,,contents ,,chapter ,i ,,general ,,introductory ,,remarks ,,on ,,some ,,of ,,the ,,leading ,,physical ,,features ,,of ,,the ,,island ,its remarkable shape1 #a4--;,its building up1 #b4--,study of its profile1 #c4--,mount ,seatura4--,regions of acid andesites4--,basaltic tablelands4--,great ridge-mountains1 #e4--;,boundary of the regions of basic and acid rocks1 #f4--;,its primary features1 the dacitic peak1 the basaltic plateau1 and the ridge-mountain ,pages #a-f ,,chapter ,,ii ,,on ,,the ,,evidence ,,of ,,emergence ,,or ,,of ,,upheaval ,,at ,,the ,,sea-,,borders ,elevated coral reefs scantily represented1 #g4--;,apparent absence of coral reefs in the early stages of the emergence1 #h4--;,elevated reefs confined to the coast and its vicinity4--,detailed examination of the sea-borders1 #i4--,silicified corals and siliceous concretions the only evidence in many localities of the upraised reefs1 #ac4--,the relations of the mangrove-belt to the reef-flat1 #ad4--;,indications of a very gradual movement of emergence in our own time1 #ae4--,the rate of advance of the mangroves1 #af4--;,conclusions1 #ai ,pages #g-bj ,,chapter ,,iii ,,the ,,hot ,,springs ,,of ,,vanua ,,levu ,the thermal springs of other parts of the group1 #ba4--,the hot springs of the ,wainunu valley1 #bb4--,the boiling springs of ,savu-savu1 #be4--;,analyses of the water1 #bh4--,the hot springs of other localities1 #ca4--;,distribution of the springs1 #ce4--,the alg and siliceous deposits1 #cg4--,the cold and thermal springs of ,hawaii and ,etna1 #ch4--;,infiltration1 the source of the springs1 #ci4--;,a view negatived by ,prof4 ,suess4--,list of the hot springs of ,vanua ,levu1 #dj4--,summary of the chapter1 #db ,pages #ba-db ,,chapter ,,iv ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features ,,of ,,vanua ,,levu ,naivaka1 #dc4--,korolevu ,hill1 #de4--;,bomb formation of ,navingiri1 #df4--,remarkable section near ,korolevu1 #dh4--,wailea ,bay to ,lekutu1 #ej4--,mount ,koroma1 #ea4--,mount ,sesaleka1 #ec4--,the ,mbua-,lekutu ,divide1 #ee4--,the ,mbua and ,ndama plains1 #ee4--,the shell-bed of the ,mbua river1 #eh4--,lekumbi ,point1 #fj ,pages #dc-fj ,,chapter ,v ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,mount ,seatura1 #fa4--;,its eastern slopes1 #fc4--;,its western slopes1 #fd4--;,its northern slopes1 #fe4--;,ascents to the summit1 #ff4--,the ,ndriti ,basin1 #fg4--;,a huge crateral cavity1 #fh4--;,its dykes of propylite1 #fi4--,seatura a basaltic mountain of the ,hawaiian order1 #gb4--,the ,seatovo ,range1 #gc4--,solevu ,bay1 #ge4--,koro-i-rea1 #gg4--,nandi ,bay1 #gh4--,na ,savu ,tableland1 #gi ,pages #fa-ha ,,chapter ,,vi ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the basaltic plateau of ,wainunu1 #hb4--;,its margins covered by pteropod and foraminiferous ooze-rocks1 #hf4--,the hill of ,ulu-i-ndali1 #hg4--,kumbulau ,peninsula1 #ij4--,the basaltic flow of ,kiombo ,point1 #ib4--,soni-soni ,island1 #ic4--,yanawai coast1 #ie ,pages #hb-ig ,,chapter ,,vii ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the ,ndrandramea district1 #ih4--;,its mountains and hills of acid andesites1 #ajj4--,ngaingai1 #aja4--,ndrandramea1 #ajb4--,soloa ,levu1 #ajc4--,the underlying altered acid andesites1 #ajf4--,section of the district1 #ajg4--,the magnetic peak of ,navuningumu1 #ajh4--,the ,mbenutha ,cliffs and their pteropod and foraminiferous beds1 #aji ,pages #ih-aab ,,chapter ,,viii ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,mount ,vatu ,kaisia and district1 #aac4--,the ,nandronandranu district1 #aag4--,nganga-turuturu cliffs1 #aai4--,ndrawa district1 #abj4--,tavia ranges1 #aba4--,na ,raro1 #abc4--;,its ,ascent1 #abe4--,na ,raro ,gap1 #abg ,pages #aac-abg ,,chapter ,,ix ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the basaltic plains of ,sarawanga1 #abi4--,tembe-ni-ndio and its foraminiferal limestones1 #aca4--,the basaltic plains of ,ndreketi1 #acb4--,the ,nawavi ,range1 #ace4--,nanduri1 #acf4--,tambia district1 #acg4--,the basaltic plains of ,lambasa1 #ach ,pages #abh-aci ,,chapter ,x ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the ,va ,lili ,range1 #adj4--;,its ,nambuni spur1 #add4--,originally submerged and covered with palagonite-tuffs and agglomerates1 #ade4--,the ,waisali ,saddle1 #adf4--,narengali district1 #adg4--,nakambuta1 #adh4--,the valleys of the ,ndreke-ni-wai1 #aej4--,their origin1 #aea ,pages #adj-aeb ,,chapter ,,xi ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the ,korotini ,range1 #aec4--,traverse from ,waisali to ,sealevu1 #aed4--,traverse from ,mbale-mbale to ,vandrani1 #aef4--,traverse from ,vatu-kawa to ,vandrani1 #afj4--,traverse from ,nukumbolo to ,sueni1 #afa4--,the ,sueni valley1 #afc4--;,general inference concerning the range1 #afd ,pages #aec-afe ,,chapter ,,xii ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the ,koro-mbasanga ,range1 #aff4--,the ,sokena ,ridge1 #afi4--,lovo valley1 #afi4--,mount ,mbatini1 #agb4--,the ,vuinandi ,gap1 #age4--,the ,thambeyu or ,mount ,thurston ,ranges1 #agf4--,structure of ,thambeyu1 #agg4--,the ,avuka ,range1 #agi ,pages #aff-ahj ,,chapter ,,xiii ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the ,valanga ,range1 #aha4--;,its western flank1 #ahc4--,ngone ,hill1 #ahc4--,valley of ,na ,kula1 #ahd4--,the ,mariko ,range1 #ahe4--,savu-savu ,peninsula1 #ahi4--,naindi ,bay1 #aib4--,the ,salt ,lake1 #aid ,pages #aha-aif ,,chapter ,,xiv ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the ,natewa ,peninsula1 #aig4--,viene district1 #aih4--,lea district1 #aii4--,waikawa ,mountains1 #bja4--,ndreke-ni-wai coast1 #bjc4--,waikatakata1 #bjc4--,mount ,freeland or the ,ngala ,range1 #bjd4--,traverse from ,tunuloa to ,ndevo1 #bje4--;,coast from ,ndevo to ,mbutha ,bay1 #bje ,pages #aig-bjf ,,chapter ,,xv ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the north-east portion of the island from ,mount ,thurston to ,undu ,point1 #bjg4--;,coast between ,vuinandi and ,tawaki1 #bjh4--,the corresponding inland region1 #bji4--,the gabbro of ,nawi1 #baa4--,uthulanga ,ridge1 #baa4--;,ascent of ,mount ,vungalei or ,ndrukau1 #bac4--,nailotha1 #bad4--;,exposure of altered trachytes and quartz-porphyries at its base1 #bae4--;,from ,nandongo to ,vanuavou1 #baf4--;,from ,ngelemumu to ,wainikoro1 #bag4--,sea border between ,lambasa and ,mbuthai-sau1 #bah4--;,coast between ,mbuthai-sau and the ,wainikoro and ,langa-langa ,rivers1 #bai4--;,coast between the ,langa-langa ,river and ,thawaro ,bay1 #bba4--,the ,globigerina clay of ,visongo1 #bba4--,vui-na-,savu ,river1 #bbb4--,some ,general inferences1 #bbc ,pages #bjg-bbc ,,chapter ,,xvi ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,the ,wainikoro and ,kalikoso ,plains1 #bbd4--,vaka-lalatha ,lake1 #bbe4--;,its floating islands1 #bbf4--;,a region of acid rocks1 #bbg4--,silicified corals and limonite1 #bbh4--,tawaki district1 #bbi4--,thawaro district1 #bcj4--,mount ,thuku1 #bca4--,undu ,point1 #bcb4--;,general characters of the ,undu ,promontory1 #bcc ,pages #bbd-bcd ,,chapter ,,xvii ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu ,their varied character1 #bce4--,their classification1 #bcf4--;,descriptive formula1 #bcg4--,synopsis1 #bci4--,orders of the ,olivine-,basalts1 #bda4--,orders of the ,augite-,andesites1 #bde4--,orders of the ,hypersthene-,augite-,andesites1 #bdg4--;,description of the ,plutonic ,rocks1 #bdi ,pages #bce-bea ,,chapter ,,xviii ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,the ,olivine ,basalts ,pages #beb-bfe ,,chapter ,,xix ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,the ,augite-,andesites ,pages #bff-bhd ,,chapter ,,xx ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,the ,hypersthene-,augite-,andesites ,pages #bhe-bib ,,chapter ,,xxi ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,,the ,,acid ,,andesites1 ,,trachytes1 ,,quartz-,,porphyries4 ,the ,hornblende-,andesites of ,fiji1 #bic4--,occurrence of ,dacites in ,fiji1 #bid4--,suggestion of 8felsitic andesite0 as a rock-name1 #bie4--,the ,acid ,andesites of ,vanua ,levu1 #bie4--,the ,hypersthene-,andesites1 #bif4--,the ,hornblende-,hypersthene-,andesites1 #bih4--,the ,quartz-,andesites or ,dacites1 #cjb4--,tabular comparison of the ,acid ,andesites1 #cjd4--,the characters of the ,rhombic ,pyroxene1 #cjf4--,magmatic ,paramorphism1 #cjf4--,the ,oligoclase ,trachytes1 #cjh4--,quartz-,porphyries and ,rhyolitic rocks1 #cji ,pages #bic-caa ,,chapter ,,xxii ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,basic pitchstones and basic glasses1 #cab4--,volcanic ,agglomerates1 #cad ,pages #cab-caf ,,chapter ,,xxiii ,,calcareous ,,formations1 ,,volcanic ,,muds1 ,,palagonite-,,tuffs ,general ,character1 #cag4--;,coral ,limestones1 #cah4--;,foraminiferal ,limestones1 #cai4--,pteropod-oozes1 #cbj4--;,foraminiferous ,volcanic ,muds1 #cba4--,samples1 #cbb4--;,altered kinds1 #cbd4--,submarine ,palagonite-tuffs of mixed composition1 #cbf4--,samples1 #ccj4--;,altered ,basic ,tuffs1 #ccb4--,submarine ,basic ,pumice ,tuffs1 #ccc4--8;,crush-tuffs0 formed of basic glass and palagonite1 #ccd4--,zeolitic ,palagonite-,tuffs1 #ccd4--,palagonite-marls1 #cce4--;,acid ,pumice ,tuffs1 #ccf ,pages #cag-ccf ,,chapter ,,xxiv ,,palagonite ,its abundance in a fragmental condition in ,vanua ,levu1 #ccg4--;,its occurrence in deep-sea deposits1 #cch4--,modes of formation in situ1 #cch4--;,in the upper portion of a basaltic flow1 #cci4--;,in the groundmass of hemi-crystalline basaltic rocks1 #cci4--;,in veins in a basic tuff-agglomerate1 #cdj4--;,in the fissures of a basaltic dyke1 #cda4--;,in the matrix of pitch-stone agglomerates1 #cdi4--;,in 8crush-tuffs10 #cda4--,regarded as a solidified magma-residuum of low fusibility1 #cdb4--;,its connection with crushing1 #cdb4--;,bunsen's experiment1 #cdc4--,rosenbusch and ,renard1 #cdd4--,the ,nandua series of beds1 #cde4--,suggested explanation of the origin of palagonite1 #cdf4--,type of basalt associated with palagonite1 #cdg4--;,hydration and disintegration of palagonite1 #cdh ,pages #ccg-cdi ,,chapter ,,xxv ,,silicified ,,corals1 ,,flints1 ,,limonite ,mode of occurrence of the silicified corals1 #cea4--,their character and structure1 #ceb4--;,flints1 nodules of ,chalcedony1 ,agates1 etc41 #cec4--,other siliceous concretions1 #ced4--;,jasper1 #cee4--;,deposits of ,limonite1 #cef4--,magnetic ,iron-sand1 #ceg4--,suggested explanation of the silicification of the corals1 #ceh4--,note on a silicified ,tree-fern1 #cfj ,pages #cej-cfj ,,chapter ,,xxvi ,,magnetic ,,rocks ,previous observations1 #cfa4--,magnetic ,polarity usually caused by atmospheric electricity1 #cfb4--;,displayed by both acid and basic rocks1 #cfd4--,very frequent in ,vanua ,levu1 #cfe4--;,its relation to specific weight1 #cff4--,the influence of locality1 #cfg4--;,frequently observed in mountain peaks1 #cfg4--;,description of the peaks1 #cfh4--,measurement of the polarity of rocks1 #cgj ,pages #cfa-cga ,,chapter ,,xxvii ,,some ,,conclusions ,,and ,,their ,,bearings ,vanua ,levu1 a composite island formed during a long period of emergence1 #cgb4--,the submarine plateau probably produced by basaltic flows1 #cgc4--,the distribution of the volcanic rocks1 #cgd4--;,comparison with ,iceland1 #cgd4--,the mountain-ridges1 #cge4--,the emergence of the ,fiji ,islands1 #cgf4--,wichmann's view of the early continental condition not supported1 #cgf4--;,age and character of the emergence1 #cgg4--,the evidence of the ,lau ,group and of the ,tongan ,islands1 #cgh4--,two principal stages of the emergence1 #cgi4--,relative antiquity of the ,hawaiian1 ,fijian1 and ,tongan ,islands as indicated by their floras1 #cgi4--;,islands have always been islands1 #chj4--,the hypothesis of a ,pacific continent not yet needed1 #cha4--,the great dilemma1 #cha4--,much remains to be learned of the possibilities of means of dispersal in the past and in the present1 #chb ,pages #cgb-chb ,,appendix4 7#a7 ,note on microscopical examination of stone-axes4 7#b7 ,note on the ascent of the tide in the ,ndreketi ,river4 7#c7 ,note on the 8talasinga0 districts4 ,,index #che ,,list ,,of ,,illustrations ,,plates ,,to ,,face ,,page ,na ,raro 7#b1dbj feet7 from the south-west1 a peak of acid andesite ,frontis- ,ndrandramea 7#a1hjj feet7 from the south-east1 a peak of piece acid andesite rising about a thousand feet from its base ,the ,ndrandramea ,district from the westward #ih ,mount ,tavia 7#b1baj feet7 from ,vatu ,kaisia #ajh ,the magnetic peak of ,navuningumu 7#a1ica feet7 from the south ,mbenutha ,cliffs1 showing volcanic agglomerates overlying tuffs and clays1 containing shells of pteropods and foraminifera1 which are raised #a1ajj feet above the sea #aaa ,duniua ,lagoon1 representing an old mouth of the ,ndreke-ni-wai #aec ,,lithographs ,vanua ,levu1 ,fiji ,islands #a ,fiji ,islands #cgc ,,figures ,,page ,profiles of ,vanua ,levu as ,viewed from the ,south4 ,graphically ,represented on a ,horizontal ,scale of about #af miles to the inch #d ,korolevu ,hill 7#hjj feet7 from ,wailea ,bay #df ,profile and ,geological ,section of the western end of ,vanua ,levu from the ,wainunu estuary across the summit of the basaltic mountain of ,seatura to the edge of the submarine platform off the ,ndama coast as limited by the #ajj-;fathom line #fb ,profile1 looking north from off the mouth of the ,wainunu ,river #hc ,rough plan of the ,ndrandramea district in ,vanua ,levu2 made with prismatic compass and aneroid by ,h4 ,b4 ,guppy #ii ,profiles of ,ngaingai and ,wawa ,levu from ,nambuna to the south-west4 ,both are dacitic mountains #aja ,profile and ,geological ,section of ,vanua ,levu1 across the island from the ,sarawanga 7north7 coast to the ,yanawai 7south7 coast #ajg ,profile-sketch of the ,vatu ,kaisia district from ,s4,s4,e4 #aac ,section of the ,vatu ,kaisia district #aae ,profiles of ,na ,raro #abd ,profile-sketches of the ,va-,lili ,range #ada ,profile-sketch of the mountainous axis of ,vanua ,levu #afg ,koro-mbasanga from the north-north-east #afg ,mount ,mbatini from the top of ,koro-mbasanga #agc ,view from ,muanaira on the south coast of ,natewa ,bay #agc ,ideal ,section of ,thambeyu #agg ,diagram illustrating the two sets of felspar-lathes in a dyke #bch ,magma-lakelet1 #be mm4 in size1 magnified #bij diameters1 from a basalt at ,navingiri #cci ,showing fragments of glass with eroded borders and of plagioclase with more even edges in a matrix of palagonite traversed by cracks #cdb ,diagram showing the succession of deposits below the ,nandua tea-estate #cde ,illustration3 ,,vanua ,,levu1 ,,fiji ,,islands4 ,,drawn ,,on ,a ,,scale ,,of #be ,,miles ,,to #c ,,inches ,,by ,h4 ,b4 ,,guppy1 ,m4,b4 ,based on the ,admiralty ,surveys1 but most of the topographical details of the interior have been supplied from the author's observations with the aneroid and prismatic compass in #ahig-ii4 ,it is merely intended to illustrate his general account of the physical and geological characters of the island and is very far from complete4 7see introduction47 ,,observations ,,of ,a ,,naturalist ,,in ,,the ,,pacific ,,chapter ,i ,,general ,,introductory ,,remarks ,,on ,,some ,,of ,,the ,,leading ,,physical ,,features ,,of ,,the ,,island ,,the remarkable shape of this island at once attracts the attention3 and indeed it is in its irregular outline and in the occurrence over a large portion of its surface of submarine tuffs and agglomerates that will be found a key to the study of its history4 ,with an extreme length of #ih miles1 an average breadth of #ae to #bj miles1 and a maximum elevation of nearly #c1ejj feet1 it has an area1 estimated at #b1djj square miles1 comparable with that of the county of ,devon4 ,whilst its peculiarly long and narrow dimensions are to be associated with the narrowing of the submarine basaltic platform1 from which it rises together with the other large island of ,viti ,levu1 its extremely irregular shape is closely connected with the composite mode of its origin4 ,we have here exemplified the process of the building up of a continental island in the great area of emergence of the ,western ,pacific1 that region which displays at various heights above the sea the ancient reefs and the underlying deposits of the ,solomon ,islands1 ,new ,hebrides1 ,fiji1 ,tonga1 c4 ,but this process of construction has never been completed1 and is at present suspended2 yet it is in its incomplete condition that ,vanua ,levu possesses its importance for the investigation of this subject4 ,this island has in fact been formed by the union of a number of smaller volcanic islands during a long protracted period of emergence4 ,these original islands are indicated approximately by the #a1hjj-;feet contour-level in the accompanying map4 ,there is1 however1 no reason for supposing that the movement of emergence has altogether ceased4 ,in the course of ages the extensive submarine plateau1 from which it rises1 will be laid bare2 and the small surrounding islands that are situated upon it1 such as ,yanganga1 ,kia1 ,mali1 ,rambi1 ,kioa1 c41 will be included in the area of ,vanua ,levu4#a ,excluding for the moment the effects of denudation1 which have been very great1 we shall be able to discern some of the stages of the building-up of the island during the emergence or upheaval by looking at the map and reversing the process in imagination4 ,a subsidence of only #ej feet would cause the ,natewa ,peninsula to be isolated by a sea-passage along the line of the ,salt ,lake2 whilst several islands would be formed along the northern and southern coasts1 and the ,naivaka ,peninsula would become detached4 ,if the subsidence extended to #cjj feet1 the sea would flow over a large portion of the island1 where it would regain what was not many ages since its own1 an area of basaltic plains1 which by their prolongation under the sea form the great submarine plateau4 ,a subsidence of #a1jjj feet would break up the remaining elevated axis of the island into a number of lesser portions2 and after a total lowering of #a1hjj feet there would exist only a few scattered islands1 the arrangement of which would show but little relation to the present form of ,vanua ,levu4 ,at either end of the area there would arise from the sea the isolated volcanic peaks of ,seatura and ,ngala 7,mount ,freeland72 and between them would be situated four or five long narrow islands1 together with a group of small islands and islets where ,na ,raro and the other acid andesite mountains of the ,ndrandramea district now lie4 ,as might be partly expected1 there is in the surface-configuration of the interior of ,vanua ,levu an absence of that simplicity of contour which exists in a volcanic island of supra-marine formation1 as for instance in the large island of ,hawaii where the three great volcanic mountains of ,mauna ,kea1 ,mauna ,loa and ,hualalai together with the older ,kohala range1 determine the form of the whole island's surface4#b ,here in ,vanua ,levu there is1 on the contrary1 but little order amongst its physical features4 ,the rivers often run obliquely with the sea-border1 whilst mountains frequently rise at the coast and plains lie far inland1 and the view of the elevated interior1 as obtained from one of the peaks1 presents in many parts a series of mountain-ridges running athwart the island's axis4 ,a study of the profile of the island is an important preliminary step to its more detailed examination4 ,one may ramble over a particular region of it for weeks1 as ,i have done1 without getting any satisfactory idea of the true configuration of the surface4 ,in a locality densely wooded and occupied by steep mountain ridges and deep gorges1 the field of view is often very limited2 but seen from the deck of a passing ship the main features of the island assume their true proportions and relations1 and much that was uncertain is in this manner made plain4 ,the profile here given has been constructed from a number of others1 and represents in a graphic fashion ,vanua ,levu as viewed from the southward4 ,i have here sacrificed smaller details and occasionally some degree of accuracy in small matters in order to bring out the principal features of the island4 ,at and near the extreme western extremity rise the conspicuous hills of ,sesaleka 7#a1cgj feet71 ,naivaka 7#a1fea feet7 and ,koroma 7#a1chd feet71 all of them formed of basic volcanic materials4#c ,naivaka1 which is connected with the main island by a narrow isthmus1 only about #cj feet in height1 is probably one of the most recent additions to the island's area2 and it is at the same time one of the most recent of the numerous volcanic vents that once existed4 ,the leading feature1 however1 of this end of ,vanua ,levu is the great mountain of ,seatura 7#b1hab feet71 which occupies a large part of the ,mbua province and monopolises most of the landscape whilst largely determining the form of the western extremity of the island4 ,it is a basaltic mountain of the ,mauna ,loa type1 its long eastern slope descending gently at an angle of three or four degrees for about ten miles to the mouth of the ,wainunu ,river4 ,in its deeply eroded radial valleys and gorges1 and in other respects1 it is not unlike the island of ,tahiti1 as described by ,dana4 ,the ,ndrandramea region to the eastward1 which ,i have named after one of its best known peaks1 has a profile of a very different character4 ,its broken outline indicates the existence of numerous mountains and hills of acid andesites1 occasionally dacitic4 ,although some of them attain a height of #b1jjj feet and over their tops alone are seen from seaward4 ,between the foot of these mountains and the south coast extends a great plateau of columnar basalt1 incrusted at its borders with submarine deposits1 which descends coastward with a very gentle slope1 the fall in about five miles being only about #cjj feet 7#a1ajj to #hjj feet74 ,it terminates abruptly opposite the elevated headland of ,ulu-i-ndali1 a range1 composed mainly of grey olivine-basalts1 which is not indicated in the profile4 ,,profiles ,,of ,,vanua ,,levu ,,as ,,viewed ,,from ,,the ,,south4 ,,graphically ,,represented ,,on ,a ,,horizontal ,,scale ,,of ,,about #af ,,miles ,,to ,,the ,,inch4 ,illustration3 ,from ,,naithombothombo ,point to ,,undu ,point1 representing the length of the island 7#ih miles74 ,illustration3 ,the ,,natewa ,peninsula from the ,salt ,lake to ,kumbalau ,point4 ,the two conical peaks of ,vatu ,kaisia 7#a1hhj feet7 and ,na ,raro 7#b1dbj feet71 which rise up so unexpectedly in the region immediately east of the ,ndrandramea district1 are also of acid andesitic rocks1 in the last case approaching the dacitic type4 ,they lie within the borders of the area of basic tuffs1 basic agglomerates1 and basic massive rocks1 that here begins and extends eastward to ,mount ,thurston and a little beyond4 ,east of ,na ,raro there is a gap or break in the profile1 where the greatest elevation is probably not over #hjj feet2 and on its farther side rises up the mountain of ,va ,lili 7#b1icj feet71 a lofty inland ridge that lies towards the southern coast4 ,palagonite-tuffs and agglomerates are the prevailing surface-formations in this district4 ,eastwards from ,va ,lili extends for eight or nine miles a lofty1 level-topped1 and almost peakless range1 which ,i have called the ,korotini ,table-land1 after the towns once situated on its southern slopes4 ,its outline is shown in the background of the view facing page #aec4 ,it is1 however1 not so level-topped as it appears to be2 but the gradual variations in elevation between #b1jjj and #c1jjj feet1 when spread over a length of some miles1 are more or less lost in the general outline of the range as viewed from the coast4 ,basic agglomerates are principally exposed on the lower slopes2 whilst higher up1 reaching often to the summit of the table-land1 occur palagonite-tuffs containing tests of foraminifera and molluscan shells1 massive basic rocks being exposed in places4 ,the level profile of the ,korotini tableland gives place1 as one proceeds eastward1 to the broken outline of the several lofty peaks of ,mariko 7#b1hij feet71 ,mbatini 7#c1dcg feet71 ,thambeyu 7#c1abd feet7 and others4#d ,each of these peaks marks one of the bold mountain-ridges that form such a striking feature in the surface-configuration of this part of the island4 ,on the slopes of these ridges1 and often also on their summits1 appear basic agglomerates and palagonitic tuffs and clays often inclosing tests of foraminifera2 whilst exposed in the gorges and protruding at times through the tuffs and agglomerates on the crests of the ridges are displayed massive basic rocks of the type of the hypersthene-augite andesites4 ,east of ,thambeyu the level sinks to about #a1jjj feet above the sea1 and beyond rises an irregular group of hills and mountains which attain their greatest height in ,nailotha1#e #b1dha feet above the sea4 ,we are now near the limit of the area of basic rocks4 ,following the profile as it slopes away1 marked by occasional peaks and breaks1 towards ,undu ,point1 we pass at first over a district where basic rocks are mixed with those of more acid type2 but before we reach ,mount ,thuku we enter the district of oligoclase-trachytes1 quartz-porphyries1 and rhyolitic tuffs1 that extends to the extremity of the ,undu promontory4 ,there remains to be noticed the profile of the ,natewa ,peninsula4 ,as shown in the diagram1 this level begins at a few feet above the sea in the vicinity of the ,salt ,lake2 and as it proceeds eastward it attains a level of #a1ifj feet in ,ngalau-levu and of #a1edj feet in the ,waikawa promontory1 finally culminating1 as it nears ,kumbulau ,point1 in a mountainous district which attains its greatest elevation of #b1gdj feet above the sea in the lofty ridge of ,ngala1 the ,mount ,freeland of the chart4 ,altered basic rocks prevail in this peninsula2 but more acid andesites also occur1 and foraminiferous tuffs and clays are exposed on the slopes1 reaching to over #a1jjj feet above the sea4 ,i will conclude this reference to the profile of the island with the remark that if ,i had neglected to indicate here the close connection that exists between the nature of the surface-configuration and the character of the prevailing rocks ,i should have ignored a means of investigation which has proved of the greatest value4 ,the rock and surface characters go together4 ,the inland plateau now upheaved #a1jjj feet above the sea1 was built up by submarine flows of basaltic lava4 ,the isolated conical peak that so unexpectedly intrudes itself into the view is the dacitic core of some submarine volcano long since stripped of most of its fragmental coverings4 ,the lofty mountain-ridges that run athwart the island's breadth1 with their summits usually in the rain-clouds received their coverings of tuffs and agglomerates ages ago when they were submerged2 and now they rise to heights of over #c1jjj feet above the sea4 ,bound up with the mysterious origin of these great ridges is the history of the island of ,vanua ,levu4 ,these preliminary remarks are only intended to serve as a general introduction to the detailed description of the island and its formations4 ,the closing chapter is devoted to a summary of the principal results of my investigations4 ,,chapter ,,ii4 ,,on ,,the ,,evidence ,,of ,,emergence ,,or ,,of ,,upheaval ,,at ,,the ,,sea-,,borders4 ,,one would have expected that in an island where submarine muds and tuffs are of such common occurrence at the surface1 extending from the sea-border to elevations of #b1jjj feet and over1 upraised coral reefs would be also frequent and extensive4 ,but it is remarkable that the uplifted masses of reef-limestone1 so characteristic of the islands of the ,lau ,group1 are here very scantily represented4 ,it is certainly true that the fossiliferous volcanic muds that form the foundations of coral reefs are often exposed at and near the coast2 but the elevated reefs that ought to be found reposing on them are rarely to be observed4 ,it is not to be inferred1 however1 that in a region so remarkable for the great development of reef-formations coral reefs did not then thrive in these localities1 but rather that such a long period has elapsed since the emergence of the present sea-border that the upraised coral reefs at and near the coast have long since been in a great part stripped off by the denuding agencies4 ,notwithstanding this1 it is evident that coral reefs could never have been very extensive at the sea-border during the last stages of the emergence2 whilst they do not appear to have existed at all during the early periods of the history of the island4 ,in this connection it may be observed that hard compact limestones of any kind are rarely to be found1 and only in a scanty fashion4 ,the extensive development of dolomites and hard limestones1 described by ,mr4 ,andrews and others in the valley of the ,singatoka in ,viti ,levu1 is not a character of ,vanua ,levu4 ,the foraminiferous and pteropod clays1 which exist in the interior and often in the heart of the island1 are not overlaid by ancient reef-limestones1 but by great masses of volcanic agglomerate and coarse fossiliferous tuffs1 the foraminiferous muds in their turn covering the core of massive volcanic rocks4 ,there were no signs of coral-reef fragments in the volcanic agglomerates in any locality examined1 notwithstanding that these agglomerates are so intimately associated with the fossiliferous tuffs and clays that their submarine origin could not be doubted4 ,the conditions for reef-formation evidently did not exist in that early stage of the island's history1 when the foraminiferous tuffs and clays1 now occurring at elevations of #b1jjj feet and over1 were being deposited on the sea-bottom4 ,at some time or other1 however1 these high mountain-slopes1 previous to their emergence from the sea1 must have been within the limits of the zone of reef-building corals4 ,if reefs had been formed along those ancient coasts1 or on the original shoals1 they would have been in some cases preserved1 as in the case of the foraminiferous tuffs and clays1 by a covering of volcanic agglomerate4 ,these soft submarine deposits have been in this manner saved from the destructive effects of denudation over a large part of the island whether on the higher slopes or at the lower levels2 but no trace of reef-formation ever came under my notice in the higher regions of the interior4 ,this is a puzzling point that will have to be considered in connection with the origin of the great mountain ridges1 one of the most difficult problems in the history of the building-up of ,vanua ,levu4 ,i will now refer to the evidence of the latest stage of the upheaval of the island as indicated at and near the sea-border by the scantily occurring upraised reefs4 ,the elevated reefs are mostly to be found on the south coast between ,fawn ,harbour and ,na ,viavia ,islet off ,harman's or ,savu-savu ,point4 ,na ,viavia ,islet itself is #cjj or #djj yards in length and is formed of much honeycombed reef-limestone1 which is raised #aj or #ab feet above the high-water line4 ,proceeding eastward along the south coast of the ,savu-savu promontory we next come upon uplifted reefs in a curiously isolated hill that rises on the coast between ,naithekoro and ,naindi ,bay4 ,this hill is about #bej feet in height and is composed in the mass of coral limestone4 ,about #ajj feet above the sea-level it exhibits an erosion-line1 above which it rises precipitously to the summit4 ,the west point of ,naindi ,bay is formed of reef-limestone reaching to a height of #dj to #ej feet and displaying in position massive corals1 8,fungi10 and 8,tridacna0 shells4 ,near its base1 four to five feet above the present high-water level1 it shows an erosion line4 ,this limestone overlies a rock in which blocks of volcanic rocks1 five to six inches across1 are imbedded in a calcareous matrix4 ,raised coral limestone occurs at intervals on the coast between ,naindi ,bay and the mouth of the ,salt ,lake ,passage1 usually forming low islets1 of which the smaller about #ab feet in height often assume1 through the erosion of the sea at their base1 that peculiar mushroom-shape1 so characteristic of upheaval on reef-bound coasts4 ,the passage into the ,salt ,lake lies in a slightly elevated reef-mass2 and the islet which rises up in its centre to about a foot above the water-level is mainly formed of coral blocks1 although ,i did not find any remains of coral on the low neck of land intervening between the ,salt ,lake and ,natewa ,bay4 ,eastward from the ,salt ,lake ,passage to ,nanutha in the vicinity of ,fawn ,harbour low cliffs of coral limestone1 six to eight feet high and occasionally displaying massive corals in position1 most frequently constitute the sea-border1 rarely1 however1 extending more than a few paces inland or attaining there a greater elevation than #ab or #ae feet4 ,this limitation of the upraised reef-belt to the immediate vicinity of the coast is true of all this district4 ,it is only when the sea-border is low and swampy that it is found #ajj or #bjj yards inland2 and in any case as one follows it inland it soon gives place to the fossiliferous mud-rocks and tuffs of the interior4 ,it should be noted that the upraised reefs of this region were rarely observed at greater heights than #bj feet above the sea1 in fact usually at a much lower level4 ,the exceptional occurrence in mass of reef-limestone at a height of #bej feet in a coast hill between ,naithekoro and ,naindi therefore lends colour to the idea that the elevated reefs formerly extended farther inland and that they have been stripped off by denudation4 ,on the north coast of the ,natewa ,peninsula elevated reefs are of very rare occurrence4 ,i walked along the whole of that coast from the head of ,natewa ,bay to within four miles of ,kumbulau ,point and only found them in the locality1 one to one and a half miles west of the mouth of the river ,ndreke-ni-wai4 ,here there were two islets1 #bj to #be feet high and lying close to the shore1 which were formed entirely of coral-rock1 massive corals occurring in position in their lower part4 ,although1 however1 upraised reefs are so scantily to be found on this coast1 other proofs of upheaval are to be observed in the fossiliferous tuffs exposed occasionally by the beach4 ,on the east coast of this peninsula1 between ,ndevo and ,loa1 submarine tuffs and sandstones1 at times fossiliferous1 were alone noticed4 ,upraised reefs are also very rare on the north coast of ,natewa ,bay4 ,here again ,i traversed the whole coast from the head of the bay to ,undu ,point1 a distance as the crow flies of about #ej miles2 but ,i find no record in my notes of any elevated reef-formations4 ,however the calcareous nature of the volcanic tuffs exposed in places at the coast indicate emergence4 ,the extreme rarity1 if not the absence1 of upraised reefs on this long stretch of coast1 which is usually bordered by shore-reefs1 is very remarkable1 more especially since there is extensive evidence of upheaval in the plains of ,kalikoso in the interior1 as indicated in the succeeding paragraph4 ,on the other side of ,undu ,point1 between that headland and ,lambasa1 elevated reefs did not come under my observation1 although in the low-lying inland district of the ,kalikoso lake silicified corals are scattered about in quantity at an elevation of #bj or #cj feet above the sea4 ,but the emergence of the sea-border is shown in the occurrence of a 8,globigerina0 sedimentary tuff near ,visongo at a height of #bjj feet 7see page #bba71 and by the occasionally calcareous character of the pumice-tuffs that mainly compose the coast cliffs4 ,near ,nukundamu these tuffs of the shore cliffs inclose subangular fragments of massive corals of the size of a walnut2 whilst in a cutting between ,mbuthai-sau and ,lambasa1 about #ej feet above the sea1 ,i observed bits of coral limestone in a basic tuff4 ,mr4 ,horne refers to seams or layers of coral limestone occurring in the volcanic agglomerate of the coast cliffs between ,lambasa and ,tutu ,island4#f ,since his experience of this coast was mostly confined to a passage in a canoe along the shore1 it is very probable that he only saw the beds of white pumice-tuffs that prevail in places on this coast4 ,i found no beds of coral limestone in the shore-agglomerates of this coast1 nor does ,dana in his description of the pumiceous formation of the cliffs of ,mali ,point make any reference to them4#g ,along the stretch of #ej miles of coast between ,lambasa and ,naivaka upraised reefs are of infrequent occurrence4 ,however between ,lambasa and ,wailevu1 coral limestone is extensively exposed in a low range of hills a mile or two inland but not over #ajj feet above the sea4 ,no elevated reefs came under my notice between the mouth of the ,wailevu river and ,nanduri ,bay4 ,that a small upheaval has been recently in progress in this part of the coast is indicated by two circumstances4 ,in the first place an erosion-line about a couple of feet#h above the high-water line1 and a few paces removed from it1 is displayed in the volcanic tuff of the point bordering the reef-flat on the east side of ,nanduri ,bay4 ,in the next place there exist at different places in the midst of the mangrove-belt extensive bare mud-flats1 sometimes several hundred yards across1 which are only covered by the higher tides4 ,these flats are quite bare of mangrove or any other vegetation and are often cracked on the surface and sun-dried and firm to walk upon4#i ,these naked mud-flats in the midst of the mangrove tracts are peculiar to this part of the coast4 ,their general level must be between one and two feet above that of the mangrove belt in other parts of the island2 and ,i infer that a slight upheaval or emergence has led to the death of the mangroves in these situations4 ,i know little of the coast between ,nanduri ,bay and the mouth of the ,ndreketi ,river4 ,at two localities where ,i landed no elevated reef-formation was observed4 ,dana referring to the coast opposite ,mathuata ,island alludes only to the volcanic agglomerates4 ,the low mangrove-bordered coast between the mouths of the ,ndreketi and ,lekutu rivers was not actually visited by me2 but ,i traversed the region behind the broad mangrove-belt1 and found occasionally in the tuffs and muds exposed in the river-banks marine-shells and foraminiferous tests1 indicating an elevation of a few feet4 ,i examined much of the coast between ,lekutu and the extremity of the ,naivaka peninsula1 but came upon no upraised reef-rocks4 ,in the low isthmus1 #bj to #cj feet high1 which connects this peninsula with the main island only volcanic rocks came under my notice4 ,a palagonitic tufaceous sandstone exposed in the cliffs on the north coast of ,naivaka contains a little carbonate of lime1 and being probably a submarine deposit it implies an emergence of the sea-border4 ,although ,i have been able to produce but scanty evidence of uplifted reefs on the north coast of ,vanua ,levu1 it is probable1 judging from the heights given in the ,admiralty ,sailing ,directions1 that such formations exist in a few of the numerous low islands and islets that front this coast4 ,some of these islands and islets1 which are often not much more than reef-patches largely reclaimed by the mangroves1 will be noticed below when considering the question of the extension of the mangrove belts since the survey of ,commodore ,wilkes in #ahdj4 ,neither on the south coast of the peninsula of ,naivaka nor on the west coast of the ,sesaleka promontory did upraised reefs come under my observation2 but my acquaintance with the last locality is very scanty4 ,the emergence of the ,sesaleka promontory is however indicated by the occurrence inland at heights of at least #gjj feet of palagonitic tuffs1 occasionally containing foraminifera4 ,with the long tract of coast between ,naithombothombo ,point and ,solevu ,bay1 ,i am fairly well acquainted4 ,however1 with the doubtful exception of ,lekumbi ,point1 no elevated reef-formations were observed4 ,evidence of an emergence of a few feet1 and of a very extensive seaward advance of the land-surface in recent times1 is afforded by a curious bed of marine shells exposed in the banks of the ,mbua ,river1 nearly two miles inland and in the vicinity of the ,wesleyan ,mission station4 ,this is described on page #eh4 ,the submergence at some period of the watershed between the ,mbua and ,lekutu districts is indicated by the presence of microscopic foraminifera in the hyalomelan tuffs that are exposed in the dividing ridge4 ,along the whole coast between the mouth of the ,mbua ,river and ,solevu ,bay1 there are but few if any traces of upheaval4 ,even volcanic tuffs are of rare occurrence1 and there is only the case of the formation of ,lekumbi ,point to be here referred to4 ,this singular low cape is described on page #fj4 ,here it is sufficient to remark that it is monopolised by the mangroves except at the outer part where the swampy ground passes into the dry sandy soil of a reef-islet1 occupied by the usual littoral vegetation1 and raised only a foot or two above the high-water level4 ,it exhibits on the beach the bedded sand-rock so often found on coral islets1 but this in itself is no evidence of emergence4 ,neither on the shores of ,wainunu ,bay nor in the ,kumbulau peninsula were upraised reefs observed1 although the presence in places of submarine tuffs inland and near the coast affords evidence of elevation4 ,the same remark applies to the coasts of ,savu-savu ,bay4 ,i have little doubt that the absence of elevated reefs on the coasts of by far the greater part of the island is the result largely of denudation4 ,in this case we have to explain why an island in a region of coral reefs exhibits on the surface of its interior submarine tuffs and clays in most localities1 whilst uplifted reefs are very rarely to be found at the coast or in fact anywhere4 ,this view receives support from the existence of traces of old elevated reefs in different parts of the island4 ,these traces are afforded by the occurrence on the surface in different localities of silicified fragments of coral associated with concretions of chalcedony1 bits of flints and hornstones1 jasper1 impure siliceous nodules1 c4 ,the localities may be at the coast or a mile or two inland1 and are not usually more than #ajj or #bjj feet above the sea4 ,this subject is treated with some detail in ,chapter ,,xxv4 ,here ,i may say that such localities are confined mostly to the open1 low1 undulating districts on the north side of the island4 ,silicified corals are not always present with the fragments of chalcedony and other siliceous concretions that are found so frequently in these situations2 but from their association in the plains of ,kalikoso1 where the silicification of corals may almost be observed in operation1 the previous existence of corals may be more than suspected in localities where only the other siliceous materials are observed4 ,i pass on now to some general considerations regarding the relations of the mangrove-belt to the sea-border and the character of the slope of the land-surface as compared with that of the submarine platform4 ,an accurate conception respecting these matters will help one to avoid some pitfalls in forming an estimate of the character of the movement of emergence which this region has experienced4 ,beginning with the mangrove-belt1 some curious preliminary reflections arise1 when we endeavour to look back into the past stages of the history of a mangrove tract in an area of emergence4 ,we might perhaps expect to find the remains of such a belt in the upraised sea-borders2 or if no traces existed1 we ought to find in some places an extension inland of the reef-flat on which the mangroves at one time flourished4 ,if a rapid movement of emergence is now in progress1 the mangroves ought to cover the whole or greater part of the reef-flat2 and in the mangrove tract of an emerging area we might look for signs of central decay and marginal growth1 the mangroves dying in the middle of the tract and flourishing at the advancing margins4 ,when1 however1 we look at the mangrove-belt1 as it at present exists around much of the coast of this island1 we find that1 except in the vicinity of the mouths of rivers1 there extends beyond it a considerable extent of bare reef-flat1 varying usually between #bjj and #a1jjj yards in width1 and covered by the rising tide4 ,there is no evidence of recent emergence in this condition of things4 ,this relation between the mangrove-belt and the reef-flat indicates a state of equilibrium which might have been established long ago4 ,it is the normal relation that exists between reef and mangrove growth2 and it excludes all but very gradual movements of upheaval or emergence of the sea-border4 ,it is not always easy to see why there should be this fine adjustment between the rapidly-growing mangrove and the slowly-growing reef4 ,under normal conditions1 however1 that is to say1 when the land is stationary or when the change of level is of a very gradual nature1 the reclaiming agency of the mangrove receives a check1 and this relation between the mangrove-belt and the outer reef-flat is maintained4 ,actual acquaintance with such localities soon forced me to the conclusion that whilst a gradual emergence or upheaval of #c or #d feet in a century would not materially affect the relation between the mangrove-belt and the reef-flat1 a sudden or rapid change of level of that amount would destroy the mangroves around the whole island4 ,there is some evidence1 however1 of there having been a rapid upheaval of this kind in different parts of the coast3 and it follows1 therefore1 if this movement was general1 that the present mangrove-belts date only from the last upheaval4 ,but this elevation may have occurred ages ago2 and the equilibrium between mangrove-belt and reef-flat may have been long since established4 ,accordingly1 the breadth of the mangrove-belt can afford no indication of the period that has since elapsed4 ,from data referred to below1 it is evident that the mangrove-belt1 taking its average width1 away from the estuaries1 at about #ejj yards1 might have been formed in two or three centuries1 whilst a thousand years or more may have passed since it assumed its present relation to the reef-flat4 ,if1 therefore1 upheaval is in progress1 it must be of a very gradual character1 since the normal relation of mangrove-belt to reef-flat now prevails4 ,there are indeed signs of such a gradual movement of emergence or of elevation being in operation on the north coast of ,vanua ,levu at the present time4 ,i have before referred 7page #aa7 to the extensive bare mud-flats in the midst of the mangrove-belt between ,nanduri and ,lambasa1 which are well represented on the ,tambia coast and in ,nanduri ,bay4 ,they are only covered by the higher tides1 and in the intervals their surfaces are dried and cracked by exposure to the sun4 ,here we have the central decay and the marginal growth which would be expected in a mangrove tract situated in a gradually rising area4 ,an indirect indication of such a slow upheaval on the north coast is to be found in the circumstance that the great submarine platform1 which reaches seaward to the line of barrier-reefs1 #ae to #bj miles away1 passes gradually1 as it extends landward1 into the low-lying plains that constitute the sea-border between ,lekutu and ,ravi-ravi ,point4 ,as shown in the profile-section on p4 #fb1 these low coast districts are prolonged inland1 with an average rise of between #bj and #cj feet in a mile1 to the heart of the island2 and we have here an extension inland of the slope of the submarine platform4 ,these broad inland plains1 and ,i may here include those behind ,lambasa1 are covered over much of their surface with submarine tuffs and clays in such a manner that we may almost trace their continuity at the coast with similar deposits now in actual formation beyond the low-water level on the surface of the submarine platform4 ,a glance at the map of the island1 where these inland plains are indicated by the #cjj feet of the contour-line1 will make this point more clear4 ,these plains are traversed by the ,sarawanga1 ,ndreketi1 ,wailevu1 and ,lambasa rivers2 and so slight is the fall that cutters usually ascend the rivers for several miles1 whilst the tide extends for a considerable distance up their courses4 ,that the emergence of the inland plains of ,kalikoso in the eastern part of the island is comparatively recent there can be but little doubt4 ,in that locality as described on page #bbd1 the low marshy land1 surrounding the fresh-water lake of ,vakalalatha1 although five miles inland1 is only elevated #bj to #cj feet or less above the sea1 and silicified corals are scattered over its surface4 ,there is one other method of ascertaining the character and amount of elevation that may be still in progress in this island namely the comparison of the results of surveys of the coasts at different periods4 ,in this manner data may be obtained as regards the growth of the mangrove belt1 changes in size of the low reef-islets and islands1 and alterations in depth4 ,for this purpose ,i have employed the charts of the north and west coasts of the island made by ,commodore ,wilkes in #ahdjaj and the ,admiralty charts #cgi and #chb as completed from the survey of these coasts by ,commander ,combe in #ahie-if4 ,it was not easy to make many good comparisons in the case of the advance of the mangrove-belt of the main coast4 ,there certainly has been no great advance seaward of the margin of the mangroves in this half century4 ,the average amount probably lies between the estimate obtained for the coast opposite ,mathuata ,island1 where there has either been no change or an advance of only #ajj yards or so1 and that for the advance seaward of the mangrove promontory of ,lekutu which amounts to #ejj or #fjj yards4 ,in this last case1 however1 much of the extension may be due to the advance of the mangroves on the mud brought down by the ,lekutu river1 so that1 as far as these data show1 the average advance of the belt of mangroves on this coast between #ahdj and #ahie would appear to be slight4#aa ,on the other hand1 the mangrove-borders of the several low islands and islets1 mainly formed of reef-dbris1 that lie off the coast1 have often extended themselves during this period in a marked degree4 ,the results of my comparisons are given below1 the rate of advance being obtained by halving the increase in length or breadth as measured between the mangrove-borders1 the breadth being used in the long islands4 ,advance of the ,mangrove-,borders of ,low ,islands on the ,north ,coast of ,vanua ,levu between #ahdj and #ahie4 ,thukini1 or ,gibson ,island of ,wilkes #gjj to #hjj yards ,nangano1 or ,piner's ,island of ,wilkes #cjj to #djj ,nandongo1 or ,nuvera of ,wilkes #ejj ,talailau 7two new islands7 #djj to #ijj ,nukunuku or ,clark's ,island of ,wilkes ,not much change4 ,thakavi1 or ,day's ,island of ,wilkes ,it will be noticed that the islands of the ,talailau ,reef are not marked in the chart of #ahdj2 they are both low mangrove islands1 the largest being slightly under a mile long and the smallest a little under half a mile4 ,in ,nukuira ,island1 the ,vatou of ,wilkes1 there has been a decrease of about two-thirds of a mile during this period4 ,the difference between ,thukini in #ahdj and in #ahie is very noticeable4 ,in the time of ,wilkes the mangroves only occupied about one-third of the reef-patch4 ,now they occupy about two-thirds1 the area of the reef-patch remaining much about the same4 ,taking the minus and plus values of all the islands here measured1 the average rate of the advance of the mangrove-margins during this half-century may be placed at about #bej yards in the case of these reef-islands1 which would amount to a mile in #djj years4 ,it is probable that a long island like ,ndongo1 which is about four miles in length1 has been formed by the union of smaller mangrove islands4 ,therefore1 taking half its maximum breadth of a mile as a guide1 it would at this average rate of growth require two centuries for its formation4 ,but since the extension of the mangroves depends on the growth of the reef-patch1 which takes place on the average at a much slower rate1 it follows that this can only be a minimum limit for the age of this island4 ,we can only assume that if the reef-patch had suddenly appeared #bjj years ago1 ,ndongo ,island could by this time have acquired its present dimensions4 ,it does not follow that the mangrove border has been continuously advancing4 ,a hundred years ago there may have been a state of equilibrium between the growth of the mangrove and the reef-patch1 which does not now exist4 ,all we can say of some of these low islands is that the mangroves have been rapidly extending their margins during the last half century1 and that the normal adjustment between reef-growth and mangrove-growth1 which must have once existed1 does not now prevail4 ,there is evidence of the shoaling of the ship channel amongst these islands to the extent of about a fathom during this period4#ab ,the usual depth immediately around the patches1 on which the islands have been formed1 is #h to #aj fathoms4 ,if1 therefore1 the shoaling is a general process1 it is to be inferred that although the outward growth of the reef-patches would be usually very slow1 probably not over fifty yards in a century1 there must be times when1 in shallowing depths1 the growth of the reef-patch would be comparatively rapid2 and it is at such times that the adjustment between the relations of mangrove and reef-patch would be upset so that the advance of the mangroves would be for a time unrestricted4 ,it is1 therefore1 apparent that the rate of growth of one of these low islands is not to be determined by the rate of growth of the mangrove-tract occupying the surface4 ,the subject is a complicated one2 but ,i think enough has been said to show that the destructive agencies do not prevail on this great submarine platform on the north coast of ,vanua ,levu4 ,if the data here adduced of the increase of the low islands1 of the shoaling of the channels1 and of the advance of the delta of the ,lekutu river1#ac are well founded1 all the islands1 islets1 and reef-patches that lie along this north coast will be united to each other and to the main island within a thousand years4 ,the facts here produced do not directly indicate a movement of upheaval but they are quite consistent with the conclusion that the great movement of elevation which has built up ,vanua ,levu by the union of several smaller islands is still in operation at its coasts4 ,to assume that there is now in progress at the sea-border the same process of island-building which has produced ,vanua ,levu1 as we now see it1 is to assume a uniformity in nature's methods which is disregarded by the hypothesis that the great submarine platform1 from which the large islands of ,viti ,levu and ,vanua ,levu now arise1 represents the work of marine erosion into the flanks of the upheaved islands since the last elevation4 ,the origin of this submarine platform is dealt with in ,chapter ,,xxvii4 ,here it may be remarked that ,i regard it as older than the islands that rise from it4 ,however1 this movement of upheaval is so gradual that the utmost one can expect to do by the comparison of surveys made half a century apart is to show the lack of evidence of the destructive agency of erosion4 ,as far as the comparison admits of judging1 there seems to have been no important change on the coasts of the western end of the island during this period4 ,the low neck of land connecting ,naivaka with the main island1 if we take the low-water line in the ,admiralty chart as the limit1 had much the same breadth at the time of both surveys4 ,the depths in ,mbua ,bay remain about the same1 with perhaps a shoaling of less than a fathom in places4 ,there are two cays awash in the ,admiralty plan of this bay which were described as sand-spits in the time of ,wilkes4 ,the promontory of ,lekumbi could scarcely have been expected to show any extension during this time1 since there are depths of #aj to #af fathoms close to its extremity2 and there is in fact no difference of critical importance indicated in the charts4 ,some of the principal points of this chapter may be thus summed up3-- 7#a7 ,upraised reef-limestones are of very limited occurrence4 ,they occur at and near the coast and do not extend higher than #cjj feet4 ,their scarcity at the sea-border is to be attributed to the denuding agencies4 7#b7 ,since foraminiferous muds and sedimentary tuffs with marine organic remains occur at all elevations up to over #bjjj feet1 it is assumed that the absence of reef-limestones in the elevated interior indicates the paucity or absence of reef-growths in the early stages of the history of the island4 ,the overlying agglomerates have often preserved from destruction the soft sedimentary deposits beneath2 but they seem to have never covered over a coral reef4 7#c7 ,the relation between the mangrove-belt and the reef-flat indicates a state of equilibrium which might have been established long ago4 ,if the movement of emergence is still in progress1 it must therefore be of a very gradual nature1 since the normal relation between the mangrove-belt and reef-flat now prevails4 7#d7 ,from the circumstance that the submarine platform passes with a uniform slope into the low-lying plains1 covered with submarine deposits1 it may be inferred that a very gradual emergence is now in operation4 7#e7 ,a comparison of the charts of ,wilkes and of the ,british ,admiralty shows that on the north coast of the island during the last half century the destructive agencies of marine erosion have not prevailed4 7#f7 ,the results of the comparison of the charts1 whilst they do not directly imply a change of level1 are quite consistent with the conclusion that the movement of emergence1 which has been in operation probably since the later ,tertiary period1 is not suspended4 ,note4--,the extensive evidence of emergence presented by this island is treated in ,chapter ,,xxvii4 in connection with the whole group4 ,it is not always possible to avoid in such a discussion the use of terms such as 8upheaval0 and 8subsidence10 although there is much to be said for the terms 8negative0 and 8positive0 employed by ,suess4 ,in the present chapter1 however1 ,i have avoided committing myself definitely to any view relating to the stability either of the land or of the sea1 reserving the consideration of the subject for ,chapter ,,xxvii4 ,,chapter ,,iii ,,the ,,hot ,,springs ,,of ,,vanua ,,levu ,,the abundance of hot springs in ,vanua ,levu1 and in fact in the group generally1 is not commonly known4 ,in the earlier accounts of these islands those of ,savu-savu are often alone referred to1 not only for this island but for the whole archipelago4 ,the ,united ,states ,exploring ,expedition under ,wilkes spent six months in #ahdj in making a survey of the whole group4 ,yet ,dana1 who was attached to the expedition1 remarks that 8the only trace of actual volcanic heat which the islands appear to contain is found at ,savu-savu ,bay40#ad ,horne in his excellent account of the group1 which he visited in #ahgh1 was among the first to direct attention to the abundance of hot springs there2 but he does not enumerate many4 ,although he travelled extensively over ,vanua ,levu1 he refers to only three in that island1 namely1 at ,savu-savu1 ,wainunu1 and ,vunisawana4#ae ,it will be shown below that most of the thermal springs discovered by me might easily have been overlooked4 ,before dealing with those of ,vanua ,levu ,i will mention the other localities in the group in which thermal springs are from various sources known to me4 ,they probably form but a small proportion of those that actually exist2 but the list can be readily extended by those acquainted with special parts of the archipelago4 ,in ,viti ,levu they occur amongst other places at ,wai ,mbasanga1 on the ,singatoka river 7,horne7 and at ,na ,seivau on the ,wai ,ndina1 where ,macdonald in #ahef found temperatures of #ajf and #adj ,fahr4 in two different springs4#af ,mr4 ,thiele in more recent years referred by hearsay to some hot springs on the ,wai ,ndina4#ag ,kleinschmidt in #ahgf visited a hot spring near the village of ,nambualu in the island of ,ono which rose up in the midst of a brook and had a temperature of about #ajj ,fahr4#ah ,the same naturalist in ,july of that year1 when accompanied by ,dr4 ,max ,bchner1 came upon a hot spring issuing among the mangroves at the coast about a mile from the village of ,ndavingele in ,kandavu4 ,he did not take the temperature2 but he says that ,colonel ,smythe 7about #ahfj7 observed the temperature to be #add ,fahr4#ai ,different writers refer to extensive hot springs on the island of ,ngau4 ,they are placed near the beach1 and close to an ordinary cool spring4 ,miss ,gordon ,cumming in ,at ,home in ,fiji gives an illustration of them4 ,horne mentions a hot spring on the island of ,rambi4 ,andrews describes two others that bubble up through the limestone near the tidal zone in the southern part of ,vanua ,mbalavu4 ,both these springs are in close proximity to the junction line between the intruded andesite and the old reef rock4 ,one of them1 though not boiling1 was hot enough to scald the skin4#bj ,this list is no doubt capable of being much extended1 especially for ,viti ,levu and the ,lau ,group4 ,a description of the several systems of thermal springs of ,vanua ,levu will now be given4 #a4 ,,the ,,hot ,,springs ,,of ,,the ,,lower ,,valley ,,of ,,the ,,wainunu ,,river4--,this is one of the most extensive systems of the kind in the island4 ,the temperature of the various springs during my sojourn in this district in #ahih ranged from #ajj to #acj ,fahr4 ,those known to me are mostly situated in the lower part and at the mouth of the ,ndavutu ,creek1 one of the tributaries of the ,wainunu4 ,they open usually on the river-bank1 either close to the water or a few feet above it1 but some of them find an exit under water at the bottom of the river4 ,natives allege that hot springs occur at intervals on the left bank and at the river-bottom along the whole length of the river below ,ndavutu ,creek4 ,there is certainly a hot spring on the right side of the river's mouth near ,mr4 ,dyer's house4 ,it issues from the reef-flat and can only be observed at exceptionally low tides4 ,there is also a hot spring which rises up at the edge of the stream at ,thongea 7,cogea7 nearly a mile above ,ndavutu4 ,if the above statement of the natives is correct1 as ,i believe it is1 then these thermal springs issue along a line quite four geographical miles in length extending inland from the mouth of the ,wainunu4 ,all the springs are situated in the tidal part of the river-valley1 with the exception of that of ,thongea1 which is just above this limit4 ,they are but little elevated above the sea-level1 those exposed being usually not more than ten feet above the river and often much less4 ,this is a region of basalt1 the valley of the ,wainunu lying1 as described on page #hb1 in the fold between two great basaltic flows1 and probably representing a line of weakness1 along which the hot springs issue either from among loose blocks1 or from the soil1 or from a tufaceous sandstone4 ,they deposit little if any of the siliceous sinter which is often found in the thermal waters of this island4 ,this is due probably to their scanty exposure and to their low temperature4 ,the density of the water is near that of fresh water1 being not over #ajja4 ,the following temperatures may be useful for comparison with future observations3 ,thongea1 when not covered by the stream ,july1 #ahih1 #abg ,f4 ,ndavutu1 bath-spring at ,mr4 ,barratt's house ,usually #ajj on left bank of the creek near the landing place ,june1 #ahih1 #abf on left bank of creek near mouth ,dec4 #abg pool in foot-path on left bank ,june #b1 #aab ,july #bg1 #aaa at bottom of main river in depth of #c feet1 close to the left bank and just above the ,july #abb mouthof the ,ndavutu creek1 self-registering ,six thermometer used #b4 ,the ,hot ,springs of ,natoarau and its ,vicinity4--,this thermal system lies in the lower valley of the ,mbale-mbale branch of the river ,ndreke-ni-wai4 ,the principal springs are situated at ,natoarau1 a village about half a mile in a direct line from ,mbale-mbale1 about three miles from the coast1 and only about fifty feet above the sea4 ,they bubble up in pools near brooks1 and extend at intervals over an area probably several hundred yards across4 ,five springs came under my notice2 but there are doubtless several others in the low-lying and often swampy land of this district4 ,no deposits were noticed1 but the mode of occurrence and low temperature of the springs serve to explain this fact4 ,the following temperature observations were made by me in ,march1 #ahii3-- ,a4 ,pool #d feet across1 with sides of stone1 close to village #abf ,f4 ,b4 ,pool #aj feet wide1 a few paces from pool ,a #aad ,c4 ,pool #ab feet wide1 #ajj yards from village1 near the river #ajc ,d4 ,pool on the road to ,mbale-mbale1 mixed with surface water #ajj ,the natives and others often state that the thermal springs here and in other localities are much hotter in dry than in rainy weather4 ,this is correct in a sense1 because in wet weather the surface water would usually find access to the pools2 but there is no reason to believe that the temperature of the water at the hole of exit varies at all from this cause4 ,the temperature of pool ,a was taken at the bottom where the water bubbled up2 and probably it represents the true degree of heat of these springs1 since in the other cases observation of this point was not so easy4 ,the weather was dry during this visit2 but1 three months before1 ,i tested the temperature of this pool after heavy rain1 when the district was flooded1 and then ,i got a reading of #abg at the exit-hole of the spring4 ,another thermal spring1 which is distant about a mile from ,natoarau1 is known as ,waitunutunu1 that is1 ,warm ,water4 ,it lies about a third of a mile from the village of ,nambuniseseri1 between ,mbale-mbale and ,waisali1 and is quite four miles inland and about #ajj feet above the sea4 ,the springs bubble up into a pool1 about #ab feet across1 which is close to a brook and had a temperature in ,march1 #ahii1 of #aji-aab ,f4 #c4 ,,the ,,hot ,,springs ,,of ,,nukumbolo4--,the village of ,nukumbolo1 where the springs are situated1 lies on the banks of a tributary of the ,vatu-kawa branch of the river ,ndreke-ni-wai1 and is distant as the crow flies about six miles inland from the river's mouth4 ,the springs issue on a hill-slope from several places a few steps apart1 and are removed about a hundred yards from the river1 and from #bj to #cj feet above it4 ,their elevation above the sea would be about #acj feet4 ,the temperature taken in the two hottest places was #aeg ,f1 in ,november #ahih1 and #aeh in the following ,february4 ,as in the case of the springs of ,savu-savu and a few other localities1 the rocks are coated with siliceous sinter mixed with carbonate of lime1 and a gelatinous incrusting alga grows on the borders of tiny hollows bathed often in water of a temperature #acg-adj1 but thriving most where the temperature is #aae-abj4 ,the water runs down the slope into a series of pools made by the natives for bathing1 the temperature of the lowest pool being #ajc-aje and of the highest #abj4 ,this is one of the best localities ,i have seen in the island for the erection of thermal baths4 ,the rock pierced by the springs is apparently a basic agglomerate-tuff4 ,large blocks of a hard and somewhat altered palagonitic tuff lie around the bathing pools4 #d4 ,,the ,,boiling ,,springs ,,of ,,savu-,,savu4--,these springs figure in all the descriptions of the group1 and they are also famous amongst the natives4 ,since they were described by ,wilkes1 who visited them in #ahdj1 in his narrative of the ,united ,states ,exploring ,expedition1 many accounts of them have been written by subsequent visitors2 not infrequently they have been sketched as well as described2 and several analyses of their waters have been made4#ba ,the accounts of these springs that lie before me extend at intervals over a period of nearly sixty years2 but ,i shall allude to them only so far as they throw light on the history of the springs during this period4 ,the principal springs are situated in a slight hollow in a more or less level tract extending in from the beach1 and are distant about #aej yards from the shore and about ten feet above the sea-level4 ,they are five or six in number1 and at the time of my visits in ,july and ,november1 #ahih1 they were boiling briskly1 the thermometer readings being #bjh-baj ,f41 but the mercury probably fell two or three degrees in withdrawing the thermometer4 ,when1 as was the case when ,wilkes visited this locality in #ahdj1 there is but a slight appearance of boiling1 brisk ebullition is produced by covering them over with leaves4 ,the natives call this locality ,na ,kama1 which signifies 8the burning place10 and employed the springs extensively for cooking their food4 ,just as ,wilkes describes1 a freshwater brook runs past the springs and receives their outflow4 ,the temperature of the brook immediately above the springs is that of an ordinary freshwater stream #ge-gf ,f42 but below it is scalding4 ,the account given by ,wilkes of the spring and of the brook in #ahdj applies to them in our own time4 ,the small stones lying in the effluent channels of the springs are incrusted with siliceous sinter1 and a green alga lines the sides1 bathed generally in the steam but sometimes partially immersed in water only a few degrees below the boiling point4 ,it is noteworthy that this alga which was flourishing in ,july was all dead in ,november4 ,the scalding water also oozes through the sand of the adjacent beach in abundance for a distance of at least some hundreds of yards4 ,it is even stated that as far as ,ndaku1 a mile to the westward1 the hot springs issue at intervals through the beach4#bb ,there are evidently also extensive submarine springs close to the beach2 and probably ,wilkes was not far from the truth when he remarked that the 8whole area of half-a-mile square seems to be covered with hot springs40 ,off the beach1 a few hundred yards to the westward of the springs1 is a batch of dead reef formed of massive corals and only approachable from the shore at extreme low-tide when it is a little exposed4 ,from numerous small holes and cracks in the dead-coral hot water issues almost at the boiling point 7#baj ,f74 ,it is apparent that these springs have appeared at this particular spot since the corals grew4 ,but it is remarkable that this has been apparently going on since the visit of ,wilkes in #ahdj4 ,he refers to a coral rock1 distant one-third of a mile from the springs and #aej feet from the beach1 through which boiling water was issuing in several places4 ,this rock which was then #aj feet wide and #bj feet long1 was at his visit exposed for three feet at low-tide and covered at high-tide4#bc ,the geological characters of this locality are described on page #aia4 ,i may here remark that if these thermal springs occupy the position of an old crater1 it would require much imaginative power to restore it now4 ,the off-lying small island of ,nawi might by its situation appear to countenance this idea1 but ,i found no special indication1 when ,i examined it1 in support of this view4 ,from the geological character of the district1 ,i would infer that if a crater once existed here it was submarine and that it has been long since obliterated by marine and arial denudation4 ,the boiling springs come up through apparently a rotten volcanic agglomerate4 ,the slight hollow of three or four feet deep1 in which they lie1 was considered by ,kleinschmidt to be an old crater cavity2 but it is only #dj or #ej feet across1 and in the earlier descriptions the hollow is described as surrounded by a mound of earth4 ,as shown below1 the natives themselves may be held responsible for many changes in the surface around the springs4 ,there is1 in fact1 no trace of a crateral cavity in this district now4 ,i will now briefly notice the history of the boiling springs since #ahdj1 when they were visited by ,commodore ,wilkes4 ,at that time there were five springs1 situated in a basin #dj feet across1 and possessing a temperature of #bjj-baj ,f4 ,although there was scarcely any appearance of boiling1 rapid ebullition could be excited by covering the springs with leaves and grass4 ,the natives alleged that the springs had always been in the same condition4 ,in #ahfc1 when the ,chief of ,wainunu 7,tui ,wainunu7 came to fight the ,savu-savu people1 he endeavoured but without success to choke up the springs by heaping earth over them4 ,i was informed of this circumstance by ,mr4 ,a4 ,h4 ,barrack1 the owner of the springs4 ,miss ,gordon ,cumming also refers to it in her book ,at ,home in ,fiji4 ,when this lady visited the springs in ,august1 #ahgf1 they were intermittent in their action1 the highest making a fountain two to three feet high4 ,according to the description of ,kleinschmidt they were in the same intermittent condition in ,may of the same year4 ,there were then four springs situated in a bowl-shaped hollow4 ,the two larger springs were not constantly bubbling up1 but displayed periodic ebullitions of about twenty minutes' duration1 the waters disappearing in the intervals4 ,the other two springs were not then active4 ,horne1 who visited this locality in #ahgh1 refers to three or four principal springs situated in the centre of a hollow1 which was surrounded by a mound of earth1 the water boiling up to the height of about a foot4 ,about this time the springs entered for a while into a new phase of action and assumed the form of geysers4 ,according to information received from ,mr4 ,a4 ,h4 ,barrack and other old residents in ,savu-savu1 the waters spouted up to a height of from #dj to #fj feet1 not vertically but at an angle4 ,each outburst1 which lasted for ten or twenty minutes1 was followed by a similar interval of repose1 during which the springs dried up4 ,this continued for a month or two1 after which the springs gradually resumed their normal level4 ,when ,i visited the springs in ,july and ,november1 #ahih1 they were boiling briskly1 attaining a height of a few inches1 and showed no signs of intermittent action4 ,i come now to the different analyses that have been made of the water of these thermal springs of ,savu-savu4 ,specimens have been analysed at different times by chemists in various parts of the world1 in ,america1 in ,germany1 in ,australia1 etc41 and the results as far as known to me are now appended4 ,a4 ,analysis by ,dr4 ,c4 ,t4 ,jackson of ,boston1 ,u4,s41 of the water obtained in #ahdj by the ,wilkes ,exploring ,expedition4#bd ,specific ,gravity #ajjig4 ,temperature #eg ,f4 ,the evaporation of a quantity equal to #ajjj grains of distilled water gave #gb grains of salt1 thus composed3-- ,chlorine #cegg ,sodium #affe or ,soda #bbch4 ,magnesia #jddj ,lime #jcff ,silica and iron with a trace of phosphate of lime #jbjj ,carbonic acid #jdic ----- #fgda ,organic matter and loss #jdei ----- #gbjj ,b4 ,analysis by ,dr4 ,oscar ,pieper of ,hamburg of the water obtained by ,mr4 ,kleinschmidt in ,may1 #ahgf4be ,the report stated that the water was clear1 neutral in reaction and salt-bitter in taste1 brown flakes of hydrated iron oxide occurring in it after long standing4 ,the dissolved salts amounted to 8#hdh g4 per litre10 and the remark is made that 8the concentration is therefore not so great as in sea-water40 ,the solid constituents consisted in by far the greatest part of ,natrium and ,calcium chlorides4 ,a quantitative determination1 which on account of the small quantity of the water was confined to 8eine ,chlor und ,kalkbestimmung10 gave this result3-- ,chlor 7,chlorine7 #dgi g4 per litre4 ,kalk 7,lime7 #bca ,reckoned as ,chlornatrium 7,kocksalz7 and ,chlorcalcium1 these results were obtained3-- ,chlorcalcium 7,calcium chloride7 #dee g4 per litre4 ,chlornatrium 7,sodium chloride7 #cji ,amongst other constituents found in small quantities were ,sulphuric acid1 ,silicic acid 7,kieselsure71 ,potash1 and ,iron oxide4 ,iodine1 ,bromine1 ,nitrates1 and ,borates were completely wanting4 8,if this water10 says ,dr4 ,pieper1 8has healing properties1 it does not owe them to its chemical composition40 ,c4 ,analysis by ,mr4 ,h4 ,rocholl of sample obtained by ,mr4 ,h4 ,stonehewer ,cooper probably in #ahgg or #ahgh4bf ,total solids at #bab ,f4 #hgif per cent4 ignited #ggbf ,the residue consisted of-- ,free ,sulphuric ,acid 7,,so#c7 #jjdi ,calcium sulphate #jbfj ,calcium chloride #dcee ,magnesium chloride #jjba ,potassium chloride #jdae ,water #ajgj ,sodium chloride #bfda ------- #hhaa ,d4 ,analysis by ,prof4 ,liversidge of the ,sydney ,university of a sample of the water collected by ,dr4 ,bromlow1 ,r4,n41 about #ahgi4bg ,the specific gravity was #ajjfd at #fj ,f4 ,the total solids in solution were #ehbd grains per gallon2 but when heated to a dull red heat1 the residue was #edfi grains per gallon1 the combined water having been driven off4 ,iodine and bromine were carefully sought for1 but in vain4 ,four pints of the water were examined4 ,,composition4 ---------------------------------------- ------------------------- ,per cent4 in ,parts per ,grains per residue4 million of water4 gallon4 ---------------------------------------- ------------------------- ,silica1 insoluble #afha #accc #ibj ,silica1 soluble #jgd #eh #dj ,alumina and traces of ,iron sesquioxide #ecd #dag #bib ,aluminium chloride #afdf #abhf #ijj ,phosphoric acid traces traces traces ,calcium chloride #dfged #c1febi #beegj ,calcium sulphate #dggj #cgbg #bfji ,magnesium chloride #aed #abj #hd ,sodium chloride #dbaga #c1bidh #bcjfd ,potassium chloride #agef #acgb #ifj ,carbonic acid traces traces traces ,loss #dfj #cdj #beb --------------------------------------- #ajjjjj #g1hacj #edfia ---------------------------------------- ------------------------- ,looking at the general character of these thermal springs of ,savu-savu we may quote the remarks of ,prof4 ,liversidge and ,dr4 ,pieper that the salts in solution consist for the most part of chlorides1 the chlorides of calcium and sodium largely prevailing4 ,,comparison ,,of ,,the ,,analyses ,,of ,,the ,,water ,,of ,,the ,,savu-,,savu ,,thermal ,,springs1 ,,stated ,,in ,,grains ,,per ,,thousand ,,of ,,water4#bh ---------------------------------------- -------------------------------- ,date ,chlo- ,calcium,natrium,total col- rine4 ,sodium4,calcium4chlor- chlor- salts4,density4 lected4 ide4 ide4 ---------------------------------------- -------------------------------- ,dr4 ,jackson #ahdj #ceg #aff #jcf -- -- #gbj #ajji ,dr4 ,pieper #ahgf #dgi -- #bca #dee #cji #hdh -- ,mr4 ,rocholl #ahgh -- -- -- #dce #bfd #hha -- ,prof4 ,liversidge #ahgi 7#dej77abi7 7#adb7 #cfe #cbi #gha #ajjf ---------------------------------------- -------------------------------- ,sea-water1 tropics #aidf #aajh #jdf -- -- #cejj #ajb ---------------------------------------- --------------------------------- ,it is to be inferred from the above that the quantity of salts in solution remains about the same1 the proportion varying only in the four analyses1 which extended over a period of forty years1 between #gb and #hh grains per thousand grains of water4 ,this is considerably less than the salts in solution in sea-water1 namely #ce grains per thousand4 ,the relative proportions of the salts1 excepting those of calcium1 do not vary more than we should expect in the case of analyses made by varying methods and probably with a varying degree of exactness4 ,dana#bi considered from ,dr4 ,jackson's analysis that the water of the ,savu-savu springs is probably of marine origin2 but the absence of bromine and iodine1 as especially remarked by ,dr4 ,pieper and ,prof4 ,liversidge does not support this view4 ,we might also expect the proportion of the salts to each other to show a greater similarity to that in sea-water than they do4 ,on the other hand the total volume of water discharged1 not only by the springs proper but for several hundred yards along the beach1 and also between the tide-marks and beyond1 must be far greater than could be supplied by the rainfall of this portion of the ,savu-savu peninsula1 which is only one and a half to two miles across and #hjj feet high4 ,we must look1 ,i think1 for the source of these waters in deep subterranean streams or artesian basins that would be fed by the rains precipitated in the mountainous districts where the rainfall amounts to at least #bjj-cjj inches in the year4 ,this matter is further discussed in my general remarks on the hot-springs of this island 7page #ch74 #e4 ,,the ,,hot ,,springs ,,near ,,ravuka4--,these springs rise up in the centre of the breadth of the island about nine miles direct from the coast4 ,they are about #bjj feet above the sea and are situated on the ,ndrawa branch of the ,ndreketi ,river some two miles below the hamlet of ,ravuka4 ,they are on a small scale and ooze through a bed of rounded blocks and pebbles close to the water on the left bank4 ,their temperature in ,august1 #ahih1 was #adh ,f4 ,they are covered by the river when it is swollen by the rains1 and very probably other hot-springs issue along the river-bottom4 ,the conditions are not suitable for the formation of deposits4 #f4 ,,the ,,hot ,,springs ,,of ,,vuinasanga4--,these thermal springs are also situated in the heart of the island on a tributary of the ,ndreketi some three or four miles westward from ,va ,lili and about #aej feet above the sea4 ,on each bank of the river four or five paces from the water and three or four feet above it1 there is a small pool two to four feet wide4 ,in ,june1 #ahii1 the pool on the right bank had a temperature of #aca ,f41 and that on the left bank of #acd4 ,there were no deposits4 #g4 ,,the ,,hot ,,springs ,,on ,,the ,,south ,,side ,,of ,,the ,,nawavi ,,range4--,these springs also lie within the borders of the valley of the ,ndreketi4 ,they may be 8located0 by describing them as lying a few miles inland from the north coast fronted by ,mathuata ,island4 ,i did not visit them and have only learned of them from ,mr4 ,thomson's ,mathuata paper4#cj ,that gentleman refers to them as two in number and situated at the back of the coast range about four miles inland from the village of ,nangumu2 but no particulars are given4 #h4 ,,the ,,hot ,,springs ,,of ,,vatuloaloa4--,these springs lie on the ,mathuata ,coast in the neighbourhood of ,mathuata ,island4 ,i have not seen them1 but am indebted to ,mr4 ,thomson for the particulars here given1 which are taken from his paper above quoted4 ,mr4 ,thomson1 who discovered them in #ahhj1 named them the 8,graie0 springs4 ,they issue below high-water mark at ,vatuloaloa1 and had a temperature in #ahhj of about #adj ,f4 ,they are said to possess many valuable healing qualities4 #i4 ,,the ,,hot ,,springs ,,of ,,nambuonu4--,these springs are situated on the same part of the ,mathuata coast as those of ,vatuloaloa above referred to4 ,i learned from ,mr4 ,bulling of ,undu ,point that they issue from swampy ground half a mile inland4 ,they were discovered accidentally by a ,japanese who put his foot into them1 the temperature being sufficiently high to scald the feet1 but not at the boiling-point1 probably about #adj ,f4 #aj4 ,,the ,,hot ,,springs ,,near ,,tambia4--,these extensive springs1 situate #a to #b miles inland1 and rather under #ajj feet above the sea1 lie near the ,mathuata or north coast of the island1 some four miles west of the ,wailevu river4 ,they rise up in the midst of level country about a mile from the town of ,tambia1 and near the village of ,ngovungovu4 ,although situated in the valley of the ,tambia river1 these springs are not adjacent to the river1 and in this respect they differ from nearly all the inland hot springs4 ,the hottest spring bubbles up into a pool #e or #f feet across1 which had a temperature of #ahj ,f41 in ,march1 #ahii4 ,near by is a large deep pool1 some #bj feet or more across1 with a temperature of #ajj4 ,it receives the overflow from the smaller pool1 and apparently hot water also bubbles up at the bottom4 ,around the smaller hottest pool there is a considerable deposit of what is mainly siliceous sinter4 ,it incrusts the stones and also the oyster-shells lying about the pool in quantities1 where they have been left by the natives after their contents had been cooked and eaten4 ,some of the shells are almost decayed away1 the sinter for the most part alone remaining4 #aa4 ,,the ,,hot ,,springs ,,of ,,vandrani4--,these springs occur in the heart of the island1 about #h miles from the coast in a straight line1 and about #bgj feet above the sea4 ,this is the greatest elevation1 as far as ,i know1 at which a hot spring exists in this island4 ,here they rise up near the base of the central mountain range1 close to the head-waters of the ,wailevu river which opens into ,lambasa bay4 ,the springs bubble up into a pool1 a foot deep1 on the left side of the river1 four or five paces away from the water's edge1 and scarcely raised above it4 ,they are covered over when the river is in flood4 ,in ,february1 #ahii1 the temperature recorded by my thermometer was #ajj ,f42 but probably it was a few degrees higher at the bottom of the pool4 ,i noticed no deposits4 #ab4 ,,the ,,hot ,,springs ,,of ,,na ,,kama ,,on ,,the ,,wailevu ,,river4--,these boiling springs1 which are of an extensive character1 come up in half-a-dozen places on either bank of the river1 and are from #e to #f miles inland1 and about #ij feet above the sea4 ,they are close to the water1 and from #a to #aj feet above it4 ,the temperature of one small pool1 where the water bubbled up briskly1 was #bjd ,f4 in ,february1 #ahii4 ,in another it was #aid4 ,the water was probably at the boiling-point in some cases as it entered the pools1 and in the others it could have been only a few degrees below it4 ,the rocks of the district are agglomerates and tuffs4 ,i have no recollection of deposits of any extent around the springs4 #ac4 ,,the ,,hot ,,springs ,,of ,,vunimoli ,,on ,,the ,,lambasa ,,river4--,a few minutes' walk from ,vunimoli1 and about #ajj yards from the left bank of the river1 these hot springs issue in a place named ,vunimbele from the foraminiferous clay rock 7soapstone7 of the district4 ,they are on the side of a ditch which communicates with the river4 ,the natives have cut out of the soft rock small square basins which receive the waters4 ,the temperature of the hottest spring in ,august1 #ahii1 was #aee ,f4 ,that of others was #adj4 ,the conditions are not favourable for the formation of deposits4 ,these springs lie about #h miles inland and are rather over #ajj feet above the sea4 ,they are1 however1 small and unimportant1 and the locality in which they occur is now overgrown with vegetation and not easy to discover4 #ad4 ,,the ,,hot ,,springs ,,of ,,mbati-,,ni-,,kama ,,on ,,the ,,ngawa ,,river4--,these springs are situated in the ,lambasa district about #g miles from the coast1 and rather over #ajj feet above the sea4 ,they issue copiously from the volcanic agglomerate at a temperature of #afa ,f4 7,august1 #ahii71 and are only removed a few paces from the river1 and a foot or so above it4 ,alg flourish in the water1 and siliceous sinter incrusts the rocks4 #ae4 ,,the ,,hot ,,spring ,,of ,,nandongo ,,on ,,the ,,head-,,waters ,,of ,,the ,,wai-,,ni-,,koro ,,river4--,a few hundred yards from the village and elevated about #ahj feet above the sea there is a small pool in the clay of the river bank1 #b or #c feet above and close to the water1 which in ,september1 #ahii1 had a temperature of #ig ,f4 #af4 ,,the ,,hot ,,springs ,,of ,,natuvo ,,on ,,the ,,north ,,coast ,,of ,,natewa ,,bay4--,about a mile east of ,mbiagunu and near the village of ,natuvo1 there are two hot springs of small size which ,i visited in ,august1 #ahii4 ,one that issued on the reef-flat from the coral-rock at a temperature of #acf ,f4 was covered over towards high-tide4 ,the other issued near by at a temperature of #aca from swampy ground a few paces among the trees4 #ag4 ,,the ,,hot ,,springs ,,of ,,ndaku-,,ndaku ,,on ,,the ,,north ,,coast ,,of ,,natewa ,,bay4--,at this place about #b miles north of ,vuinandi some hot springs rise through the reef-flat1 which are only exposed at low tide4 ,at the time of my visit they were covered over by the rising tide4 ,the natives described them as not very hot and like the neighbouring hot springs of ,natuvo4 #ah4 ,,the ,,hot ,,spring ,,of ,,navakaravi1 ,,natewa ,,bay4--,the coast village thus named lies about one and a half miles north of ,were-kamba4 ,the hot spring is about a mile inland and not over #cj to #dj feet above the sea4 ,it is reached after traversing a low and often swampy tract4 ,the spring in ,august1 #ahii1 issued from a little rise at a temperature of #acc ,fahr41 and formed a rivulet #ah inches across4 #ai4 ,,the ,,hot ,,springs ,,of ,,vunisawana ,,at ,,the ,,head ,,of ,,natewa ,,bay4--,mr4 ,horne1 who was in this locality in #ahgh1 refers to these springs in his book ,a ,year in ,fiji4 ,they had at one time1 he remarks1 a wide reputation for their curative qualities2 but the people around became so poor on account of the hospitality that custom compelled them to extend to the numerous visitors that they buried up the springs4 ,mr4 ,horne was shown the site at the bottom of a muddy creek4 ,i saw it in #ahih4 ,it lies #cjj or #djj yards in from the beach and only a few feet above the sea4 ,there were no signs of heat then2 but ,i was told that when the stream close by is very low it sometimes is a little warm4 #bj4 ,,the ,,hot ,,spring ,,of ,,ndreke-,,ni-,,wai ,,on ,,the ,,south ,,coast ,,of ,,natewa ,,bay4--,this small spring issues between the tide-marks from an old reef-patch close to the shore and is only to be seen at low-water4 ,its temperature in ,may1 #ahih1 was #acj-ace ,fahr4 #ba4 ,,the ,,hot ,,spring ,,of ,,waikatakata ,,on ,,the ,,south ,,coast ,,of ,,natewa ,,bay4--,this important spring lies about four miles east of the town of ,natewa4 ,it issues on a hill-slope about #djj yards from the beach and is some #be or #cj feet above the sea2 but it is so beset by undergrowth that the source is not easy to reach4 ,boulders and blocks of a basaltic rock lie about on the slope2 and it is from under a huge boulder of five or six tons in weight that the spring emerges at a temperature of #adh ,fahr4 7,april1 #ahih74 ,there is a good volume of water1 and a series of bathing pools of varying temperature could be readily made4 ,unlike most of the inland hot springs1 it is not in connection with a stream or river4 #bb4 ,,the ,,hot ,,spring ,,of ,,ndevo ,,on ,,the ,,coast ,,opposite ,,to ,,rambi4--,i did not hear of any spring when in the locality2 but ,i learned afterwards that near a stream on the beach there is a hot spring which is covered at high tide4 #bc4 ,,the ,,hot ,,spring ,,of ,,navuni ,,near ,,fawn ,,harbour4--,this small spring is situated in a hilly district in a region where olivine-basalts prevail4 ,i was indebted to ,mr4 ,pickering for showing me its locality4 ,it lies about three-quarters of a mile inland and about #ajj feet above the sea4 ,it issues from the volcanic agglomerate a few paces from the right bank of the ,navuni stream and five or six feet above its level4 ,in ,may1 #ahih1 it had a temperature of #aab-aac ,fahr4 ,,general ,,remarks ,,on ,,the ,,hot ,,springs ,this island is therefore remarkable for the number of its hot springs4 ,in the list given on page #dj ,i have enumerated #bc localities where they occur2 but1 as shown below1 their number will probably in time be extensively increased4 ,on referring to the map it will be observed that the distribution of these springs is fairly general over two-thirds or three-fourths of the island4 ,taking this area at about #a1ejj square miles and dividing it into squares with sides of eight miles1 we should1 if the springs were quite evenly dispersed1 find a thermal system in every square4 ,even amongst the ,fijians and among the white residents the number of hot springs will cause surprise4 ,only those of ,savu-savu1 ,wainunu1 ,nukumbolo1 ,mbatini-kama1 and ,na ,kama on the ,wailevu river have been up to this time generally known4 ,the reason of this is that most of them are insignificant1 and with a temperature far below the boiling-point1 and ooze up in unlikely and out-of-the way places1 as by the water-side in little visited river-valleys1 on the reef-flats of not much frequented coasts1 and in swampy situations where they are likely to be overlooked4 ,the natives only recognise as 8,na ,kama0 the boiling or very hot springs2 and it was only after much questioning that ,i could get them to tell me of some unimportant 8wai katakata0 7hot water7 which they deemed to be far beneath my notice4 ,the natives were keenly interested in my botanical and geological investigations2 but they considered it to be beneath the dignity of a man who had seen the wonders of ,na ,savu-savu to spend some time looking for a half-forgotten thermal spring in a swamp4 ,from this cause alone ,i no doubt failed to find several springs4 ,all the boiling springs and those of very high temperature are probably known2 but as is pointed out below it is more than likely that a large number of unimportant springs remain to be discovered in many a deserted inland valley and between the tide-marks along the very extensive reef-bound coasts4 ,as above remarked the hot springs did not come under my notice in all parts of the island4 ,they are to all appearance wanting in the western or ,mbua portion1 and also in the ,undu portion north of ,natewa ,bay4 ,taking the first-named region1 it will be noticed that no hot springs are indicated in the map west of the ,ndreketi and ,wainunu rivers4 ,i made inquiries wherever ,i went1 but with no result4 ,on my writing to ,mr4 ,wittstock1 of ,mbaulailai1 who is well acquainted with the ,mbua peninsula1 he informed me that if hot springs existed in that part of the island he would probably have known of them4 ,in that portion of the island which ends in ,undu ,point ,i could neither discover nor hear of any thermal springs east of ,lambasa on the north side1 and of ,lakemba on the south or ,natewa ,bay side2 nor could ,mr4 ,bulling1 who has resided at ,undu ,point for many years1 tell me of any springs in his neighbourhood4 ,on looking at the general map it will be observed that the hot springs are confined to the area of basic rocks1 although they do not occur all over that area1 not being indicated in the map to the west of the ,ndreketi and ,wainunu rivers4 ,they are not known to occur in the region of dacites and acid andesites1 as in the case of the ,drandramea district2 and they have not been found in the area of rhyolitic and trachytic rocks that extends from ,undu ,point to ,mbuthai-sau on the north coast and to near ,tawaki on the ,natewa ,bay side4 ,the region of hot springs would be limited on the east by a line joining the ,mbati-ni-kama springs with those of ,nandongo on the ,wainikoro river and ,natuvo on the north shore of ,natewa ,bay4 ,such a line1 though lying within it1 roughly indicates the limit between the regions of basic and acid rocks4 ,the situation of the hot springs in the lower levels1 and their non-discovery at elevations exceeding #cjj feet above the sea1 are facts of importance4 ,in more than half the cases they arise close to and often on the banks of streams and rivers1 occasionally indeed at the river-bottom2 and no doubt numerous unknown thermal springs issue under water from the river beds4 ,in about a third of the known cases the springs come up on the coast between the tide-marks1 usually rising through the reef-flat4 ,at times even they are to be observed below the low tide level2 and one can scarcely doubt that there are a large number of undiscovered springs that are never exposed at the lowest tides4 ,it is also very likely that a number of hot springs issuing between the tide-marks are still to be discovered without much difficulty4 ,the same may be said of inland hot springs4 ,looking at the insignificant character of many of them and noting their occurrence in places where they might easily be overlooked1 it is highly probable1 as before remarked1 that a number of springs exist inland1 which1 though once known to the natives1 are now forgotten4 ,the interior of the island is very sparsely inhabited now2 but there is evidence of a much more populous condition in old times4 ,the present natives are fast losing the knowledge of the interior of the island which their forefathers possessed2 and many tracts in the mountain districts are far removed from existing paths4 ,from the haphazard manner in which ,i lighted upon thermal springs beside the head-waters of the ,ndreketi1 ,wailevu1 and ,wai-ni-koro rivers1 ,i cannot doubt that many more exist in similar localities not visited by me4 ,with regard to the distribution of the springs as respecting temperature1 ,i cannot find any marked arrangement either in their grouping or in the amount of elevation4 ,it is noticeable1 however1 that the three systems of hottest springs1 that of ,savu-savu 7#baj71 that of ,na ,kama on the ,wailevu river 7#bjd71 and that of ,tambia 7#ahj7 are all less than #ajj feet above the sea4 ,although the springs of highest temperature are confined generally1 with the exception of those of ,savu-savu1 to the main mass of the island1 it would seem that adjacent systems of springs may differ much in temperature4 ,the springs of ,vunimoli1 for instance1 have a maximum temperature of #aee1 which is nearly #ej lower than that of ,na ,kama1 three miles to the westward4 ,hot springs are more numerous in the region around ,lambasa than in most other districts4 ,lastly1 ,i may add that earthquakes are apparently more frequent in the ,mbua district1 where no thermal springs are known1 than in any other part of the island4 ,with regard to the deposits formed around the springs1 it may be observed that the circumstances are not usually suitable for their formation1 as for instance when they rise through the reef-flat or in swampy localities4 ,in those springs1 however1 where the temperature is over #aej ,f41 and where the water spreads over a surface so as to facilitate evaporation1 deposits of white sinter associated with alg occur1 as at ,savu-savu1 ,tambia1 and ,nukumbolo4 ,its composition varies a little in different localities4 ,at ,savu-savu it is compact and laminated and formed almost entirely of hydrated amorphous or colloid silica4 ,at ,mbati-ni-kama the siliceous sinter is more friable1 with a tendency to form opal4 ,the sinter of the ,nukumbolo springs resembles that of ,savu-savu2 but it also contains a good proportion of carbonate of lime 7#bj per cent47 in a granular form1 and that of ,tambia has the same characters4 ,it is not unlikely that this lime is derived from the decayed shells1 such as ,i have referred to in the case of the ,tambia springs4444 ,it may be here observed that ,mr4 ,weed and others1 who have studied the origin of siliceous sinter in the ,yellowstone region and elsewhere1 regard it as the secretion of alg1 mosses1 c41 that grow in hot waters 7,american ,journal of ,science1 vol4 #cg1 #ahhi74 ,i come now to some general considerations respecting the hot springs of ,vanua ,levu4 ,in the first place there is the singular fact that the inland hot springs nearly always make their appearance along the present lines of surface-drainage4 ,but ,i do not gather that the hot springs are of more recent origin than the rivers and streams1 by the side of which they rise4 ,on the contrary the hot springs are probably far older4 ,the conditions of subterranean drainage that favour the formation of springs at the surface1 whether cold or thermal1 would no doubt often determine the direction of surface drainage in a newly-formed land4 ,those familiar with modern volcanoes will recall the absence or rarity of streams and rivers1 and the frequency often of cold and thermal springs at and near the coast1 which are sometimes of such bulk at the exits that the expression 8subterranean river0 would be nearly appropriate4 ,the presence of artesian reservoirs may also in some localities be safely assumed4 ,i will here draw a little on my own experience of volcanic regions4 ,on the lava-bound coasts of the riverless southern portion of the large volcanic island of ,hawaii1 the subterranean waters issue as cold and thermal springs at numerous localities4 ,at ,punaluu1 and at ,ninoli1 a mile to the westward1 there are extensive freshwater springs at and near the beach which have a temperature of #fd ,f4 all through the year1#ca those at ,ninoli issuing as a large subterranean stream4 ,east of ,punaluu and at intervals along the ,puna coast1 springs of water1 sometimes fresh and cold with a temperature occasionally as low as #fd1 at other times mineral and thermal1 but with a temperature not usually above #ie1 issue at the surface or at the bottom of deep fissures in the old lava flows4444 ,in ,oahu1 another island of the ,hawaiian group1 where the volcanic forces have been long extinct1 artesian wells have been in extensive use for some years in the irrigation of the sugar-cane plantations4 ,the last water-bearing strata are reached at depths of #djj to #ejj feet4#cb ,the subterranean or artesian reservoirs are evidently therefore on a large scale2 yet ,oahu is scarcely one-third the size of ,vanua ,levu in ,fiji4444 ,lastly1 ,i will refer to the numerous subterranean streams that issue forth1 as cold and thermal springs1 from beneath the lavas near and at the ,etna coast1 as for instance in the vicinity of ,acireale4 ,the ,etna slopes are in great part deforested1 and in consequence soakage is relatively small1 and after heavy rains much of the water runs off in the torrents4 ,whilst in this locality ,i was impressed with these facts1 and ,i formed the opinion that in ancient times when ,etna was well wooded the discharge of subterranean streams at the coast was far greater than at present4 ,for these reasons and on other grounds1 amongst them notably the absence of recent crateral cavities1 ,i infer that the numerous hot springs are the outflows of subterranean streams1 fed originally by the 8soakage0 arising from a rainfall of at least #bjj to #cjj inches in the mountainous portions of the island4 ,such subterranean streams run probably at considerable depths1 emerging1 it is likely1 as often under the sea as they do on the land4 ,since writing the above ,i have read in the ,journal of the ,royal ,geographical ,society 7,november #aijb71 an abstract of a lecture by ,prof4 ,suess on the subject of hot springs and volcanic phenomena4 ,thermal springs1 he holds1 are supplied by hypogene waters and do not receive their salts from the sea4 ,such springs1 according to this view1 being the survivals of volcanic activity1 originate in the depths of the earth's crust and bring water to the surface for the first time1 not deriving it from infiltration4 ,it seems almost impertinent to suggest a view opposed to that of such a high authority2 but it appears to me that the frequent situation of the ,vanua ,levu thermal springs along the lines of surface-drainage requires an explanation that does not altogether exclude the agency of infiltration4 ,,list ,,of ,,the ,,hot ,,springs ,,of ,,vanua ,,levu1 #ahih-ii4 ---------------------------------------- -------------------------- ,locality4 ,coast or ,height ,near or ,siliceous ,nature ,tempera- inland4 above far from sinter4 of the ture4 sea-level4streams4 surface at the exit4 ---------------------------------------- -------------------------- #a4 ,wai- ,coast to ,sea-level ,river ,little or ,soil-cap1#ajj- nunu four to #bj or -side and none tuffs1 #acj ,f4 miles #cj feet under c4 inland water #b4 ,nato ,three to #ej to #ajj ,near ,little or ,soil-cap #aaj- -arau andfour feet brooks none #abf ,f4 vicinitymiles and from coast streams #c4 ,nukum-,six miles #acj feet ,about #ajj ,mixed with,agglomer-#aeg ,f4 bolo inland yards lime ate-tuff from carbonate river #d4 ,savu ,beach and ,sea-level ,inland ,in fair ,rotten #bjh- -savu #aej yards to #aj feetsprings quantityvolcanic #baj ,f4 inland near a agglomer- brook ate #e4 ,ravuka,nine #bjj feet ,river ,none ,pebble #adh ,f4 miles -side bed inland #f4 ,vuina-,ten miles #aej feet ,river ,none ,soil-cap #aca- sanga from -side #acd ,f4 north coast #g4 ,foot ,four ,not known ,not known ,not known ,not known,not of ,nawavimiles known4 ,range inland #h4 ,vatu- ,coast ,nil4 #adj ,f4 loaloa below high-tide mark #i4 ,nambu-,half-mile ,probably ,not known ,not known ,swampy #adj ,f4 onu inland slight 7proba- bly74 #aj4 ,tam- ,inland #ij feet ,not near ,abundant ,soil-cap #ahj ,f4 bia one and a stream a-half to two miles #aa4 ,vand-,eight #bgj feet ,river ,none ,old #ajj ,f4 rani miles -side river-bed from coast #ab4 ,na ,inland #ij feet ,river ,probably ,agglomer-#aid- ,kama1 five to -side little ates and #bjd ,f4 ,wailevu six tuffs miles #ac4 ,vuni-,inland #abj feet ,about #ajj ,none ,foramini-#adj ,f4 moli eight yards ferous #aee ,f4 miles from clay-rock river #ad4 ,mbati,inland #acj feet ,river ,in fair ,volcanic #afa ,f4 -ni-kama seven and -side quantityagglomer- a-half ate miles #ae4 ,nan- ,inland #ahj feet ,river ,none ,clay #ig ,f4 dongo four -side miles #af4 ,nat- ,coast and ,nil ,none ,reef-flat#aca ,f4 uvo between and a few and #acf ,f4 the tide- feet swampy marks ground #ag4 ,nda- ,between ,nil ,none ,reef-flat,not ku-ndaku the tide- known4 marks #ah4 ,nava-,a mile #cj to #dj ,swampy ,none ,soil-cap #acc ,f4 karavi inland feet ground #ai4 ,vuni-,from ,a few feet,near a ,not known ,soil-cap ,not sawana beach #cjj brook known4 or #djj yards #bj4 ,ndr- ,coast ,nil ,none ,old reef-#acj- eke-ni between patch #ace ,f4 -wai the tide- marks #ba4 ,wai- ,inland #be or #cj ,not near ,none ,rises #adh ,f4 katakata #djj yards feet a stream beneath a boulder of basalt #bb4 ,ndevo,on coast ,nil ,near a ,not known ,probably ,not below stream the known4 high- reef-flat water level #bc4 ,nav- ,inland #ajj feet ,near a ,little or ,volcanic #aab- uni three- stream none agglomer-#aac ,f4 quarters ate of a mile ,summary of the previous remarks on the hot springs of ,vanua ,levu4 7#a7 ,hot springs have been recorded from #bc localities1 but there are probably many undiscovered or forgotten4 7#b7 ,they are distributed over much of the island2 but have not been observed in the ,mbua or ,western end and in the ,undu extremity east of ,lambasa and ,lakemba4 7#c7 ,they are confined to the areas of basic rocks and are not known in the districts of dacites and other acid andesites or in those of quartz-porphyry and trachyte4 7#d7 ,they are always found at low elevations1 never exceeding #cjj feet4 7#e7 ,whilst more than half are situated along river and stream courses1 nearly all the remainder lie between the tide-marks4 7#f7 ,in only two localities is the temperature at or near the boiling-point4 ,in one place it is #ahj ,f41 and in most of the other springs it ranges between #ajj and #aej4 7#g7 ,siliceous sinter is formed where the temperature is over #aej4 7#h7 ,as exemplified by the water of the ,savu-savu springs the proportion of salts in solution 7#h per #ajjj7 is constant over many years2 whilst in this fact and in the relative amounts of each salt there is a sharp distinction from the composition of sea-water4 7#i7 ,the hot springs are older than the streams and rivers1 along which they are so frequently found4 ,it would appear that they are largely supplied from the 8soakage0 of the heavy rainfall in the mountains4 ,,chapter ,,iv ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features ,,of ,,vanua ,,levu4 ,,in this chapter the detailed description of the island is commenced1 beginning with the western extremity and proceeding eastward4 ,most of the petrological details are dealt with under their respective sections2 but it has been found necessary also to frequently refer to them in this connection4 ,,the ,,naivaka ,,peninsula4--,this mountainous peninsula forms the conspicuous feature of the western extremity of ,vanua ,levu4 ,amongst all the mountains of the island its appearance from a distance gave most promise of displaying the products of recent volcanic eruptions2 but as shown below it affords evidence of an antiquity nearly as great as that of the rest of the island1 although there are reasons for believing that its eruptions took place during the last stage of the emergence4 ,naivaka is connected with the adjacent relatively little elevated part of the main island by a low and narrow neck a little less than a mile in breadth4 ,in its highest part1 where it is only raised between #bj and #cj feet above the sea1 this isthmus is formed of the basic volcanic rocks of the district2 but about three fourths of its width are occupied by mangrove-swamps which are especially extensive on the south side4 ,viewed from some miles to the eastward the mountain has a regular conical outline2 but from the south1 when seen from ,ruku-ruku ,bay1 it has an elongated and a much more irregular profile1 descending rapidly on the east side1 but displaying a gradual and a fairly regular slope of about #aj degrees on the west side4 ,the upper part of the mountain is in the form of a curve with the concavity facing south1 the crest being more or less broken up into five or six peaks showing often precipitous and at times vertical rocky faces having a drop of from #ajj to #cjj feet1 the highest peaks ranging from #aejj to #afeh feet above the sea4 ,all around the mountain1 except on the upper steep portion on the south side where it is well-wooded1 the slopes have the usual character of the 8talasinga0 districts1 being occupied only by grass1 ferns1 cycads1 and the ordinary scanty vegetation of such regions4 ,whilst on most sides the surface configuration is fairly regular and the ascent to the summit is more or less regular1 on the south side bold spurs with valleys between them descend to the coast1 and the central mass rises abruptly in the middle of the peninsula from a height between #cjj and #ejj feet above the sea4 ,it is on this side that ,naivaka has the appearance of having been originally a crateral mountain1 of which1 however1 only the north segment in a much degraded condition now remains1 whilst the other two-thirds have disappeared4 ,the prevailing rocks are a blackish compact olivine-basalt1 having as a rule much smoky glass in the ground-mass and possessing a specific gravity of #bib-bid4 ,they are referred to in the description of genus #be of the olivine-basalts given on page #bei4 ,these rocks compose the agglomerate and the agglomerate-tuffs that form the eastern portion of the summit and probably most of the elevated part of the mountain4 ,similar agglomerates occur along most of the north coast1 the rock being in a few places scoriaceous or amygdaloidal2 and they occur in huge fallen masses on the south side near the foot of the precipitous portion4 ,the blocks in the agglomerate of the summit are usually six to eight inches across4 ,on the south-west side the massive rocks exposed are less basic with a specific gravity of #bgf to #bgi4 ,they are also more altered1 the olivine being infrequent and the interstitial glass scanty4 ,they differ besides in the parallel arrangement and in the length of the felspar-lathes 7#ah mm471 which are on the average half as long again as those of the prevailing olivine basalts 7#ab mm474 ,they are placed in a different order of these rocks and belong to genus #cg described on page #bfb4 ,tuffs did not come frequently under my notice4 ,at one part of the north coast the cliffs are formed of a palagonitic tuff-sandstone1 effervescing with an acid1 which is described on page #ccj4 ,although no organic remains are to be noticed1 it is probably a submarine deposit4 ,on a spur on the south-west side1 at an elevation of #fjj feet1 there is exposed a hard red palagonitic tuff dipping away from the summit at an angle of #dj4 ,it is mainly composed of the palagonitised dbris of a vacuolar basic glass and incloses broken and entire crystals of plagioclase1 augite1 and olivine4 ,the augite crystals1 which attain a length of five or six mm41 project from the weathered surface and are easily detached1 lying about in quantities on the ground in places4 ,although they are now imbedded in evidently a submarine tuff1 these pyroxene crystals could only have been ejected as such from a subaerial vent2 and it would therefore appear that they fell into the sea around the shores of a volcanic island in a state of activity4 ,these crystals are often cracked and are as a rule not so perfect as those ,i have gathered from the slopes of ,vesuvius1 ,stromboli1 and ,etna4 ,they exhibit an unusual tabular form arising from the great development of the clinopinakoid at the expense of the orthopinakoid faces4 ,on the whole it may be inferred that the ,naivaka volcano was submerged at the time of its origin1 but that the eruptions continued after it began to show itself above the sea4 ,in many of its features1 especially in the character of the agglomerate that forms its upper portion1 and in the palagonitic nature of the tuffs1 ,naivaka differs only from other elevated districts of the island1 where organic remains occur1 in the absence of such remains4 ,its form bears testimony to the extreme degradation we find in other districts1 and the occurrence of foraminiferous tuffs high up the neighbouring slopes of ,mount ,sesaleka affords additional evidence of the original submergence of this district4 ,,the ,,hill ,,of ,,korolevu4#cc--;,about three miles east of ,mount ,naivaka there rises to a height of #hjj feet1 about a mile inland from the shores of ,wailea ,bay1 the singular flat-topped hill of ,korolevu4 ,it displays vertical cliff-faces1 with a drop often of #bjj or #cjj feet1 which have become so deeply furrowed or fluted by the eroding atmospheric agencies that they appear at a distance to be made of columnar basalt4 ,the hill is1 however1 formed in mass of a compacted tuff or agglomerate tuff built up of materials of a hyalomelan basic glass that has undergone partial conversion into palagonite4 ,in the upper thirds these rocks show no bedding1 but in the lower slopes on the seaward side they are bedded and dip to the north away from the summit at an angle of #ae or #bj4 ,the form of this hill is well shown in the sketch attached1 and there is little doubt that we have here an old volcanic 8neck10 the remains of a submarine vent4 ,a specimen of the tuff from the summit is made up of compacted fragments1 in size ranging up to one third of an inch1 of a bottle-green vacuolar glass1 which fuses readily in a lamp-flame and is not dissolved by hydrochloric acid4 ,this glass is usually isotropic1 but much of it is also palagonitic and feebly refractive1 the vacuoles or steam-holes1 which are often elongated1 being in the last case filled with the same palagonitic material4 ,plagioclase crystals occur macroscopically in the glass2 they are much eroded and contain numerous large inclusions both of the clear isotropic glass and of its palagonitised form4 ,illustration3 ,korolevu ,hill 7#hjj ft47 from ,wailea ,bay4 ,about a third of a mile west of the ,korolevu hill rises the hill of ,ngangaturuturu1 #dej feet high1 which presents a precipitous cliff-faced summit in which are exposed basic tuffs showing pyroxene crystals projecting from the weathered surface4 ,,the ,,bomb ,,formation ,,of ,,navingiri4--,a mile north-west of ,korolevu ,hill1 where the coast road crosses a spur at the back of ,navingiri1 a very curious formation is exposed at an elevation somewhat under #bjj feet above the sea4 ,here there are to appearance a number of large more or less spherical volcanic bombs1 two to three feet across and formed of a semi-vitreous scoriaceous basalt1 imbedded in a hyalomelan-tuff displaying the same microscopical characters as in the case of the tuff forming the adjacent hill of ,korolevu4 ,the ash is light grey in colour and rather friable2 but where in contact with the bombs it becomes darker and is hardened4 ,the steam pores of the bombs are round and not elongated2 and as is usual with these bodies they increase in size from the outside1 where they are very small 7#a millimetre and less71 to the centre1 where they vary from two to five millimetres across4 ,a vitreous border1 about an inch in breadth1 forms the outer shell of the bomb where it is in contact with the tuff4 ,some of the bombs are only two or three inches apart2 and one of them shows evidence of fracture1 fragments of the outer vitreous shell lying imbedded in disorder in the surrounding tuff4 ,before entering into more detail it may be at once observed that the contiguity of some of the bombs to each other makes it at first difficult to view them as having been formed in the manner volcanic bombs are supposed to originate4 ,those who have seen the huge bombs lying scattered about on the summit of ,vulcano in the ,lipari ,islands will appreciate the difficulty of imagining how these bombs can occur in such a close arrangement without having often shattered each other to fragments4 ,however1 ,mr4 ,wittstock of ,mbaulailai in a letter to me describes even larger bombs that came under his notice exposed on the surface in the ,mbua district1 their outer crust when broken looking 8like the slag of a blast-furnace40 ,the bomb-rock is a semi-vitreous basaltic andesite4 ,it displays microporphyritic plagioclase in a ground-mass formed mainly of a smoky1 almost isotropic glass1 in which numbers of felspar microliths 7#a mm47 are developed1 the augite being but slightly differentiated4 ,scattered about in the glass are little irregular patches1 or 8lakelets10 of residual magma composed of a yellowish feebly refractive material that ,i cannot distinguish from palagonite4 ,the ash1 in which the bombs are imbedded1 is a somewhat friable hyalomelan-tuff composed of fragments of basic glass often partially palagonitised1 and usually #b or #c mm4 in size4 ,in it occur pumiceous lapilli of the same material up to #b centimetres in diameter4 ,the glass is markedly vacuolar1 the cavities being either filled with gas or with alteration-products4 ,the vacuoles are often drawn out into tubes1 giving the glass a fibrillar appearance4 ,the numerous plagioclase phenocrysts inclosed in the glass are much honeycombed and contain large inclosures of the glass1 both altered and unchanged4 ,although the line of contact is well defined in a hand-specimen1 the two rocks cannot be separated along the junction4 ,in a thin section1 in which the union of the vitreous shell of the bomb with the ash is well shown1 there is no defined line of demarcation1 the non-vacuolar isotropic glass of the bomb being there broken up into fragments1 with the interspaces filled with the partially palagonitised pumiceous ash4 ,in the vitreous shell the felspar microliths are much less developed both in size and number than in the central portion of the bomb4 ,numerous cracks communicating with the round steam-pores1 which are much larger than the vacuoles of the ash-glass1 are filled with the same yellowish magma-exudation referred to in the case of the rock forming the centre of the bomb4 ,through the cracks this palagonite-material has found its way into the steam-pores4 ,it would appear from the above that the bombs were but partially consolidated when they fell into the bed of ash4 ,the tuff is somewhat 8baked0 where it is in contact with the bombs2 and there is evidence of a collision between the bombs in the fragments of the vitreous shell imbedded in the ash4 ,although the ash itself contains no organic remains1 there occur1 not many hundred yards away and at an elevation #ajj feet higher above the sea1 foraminiferous tuffs of basic glass which are described below4 ,there is no indication of a crateral cavity in this locality2 whilst the ancient 8neck0 represented by ,korolevu ,hill is a mile away4 ,these bombs most probably after being ejected from some sub-aerial vent fell into the sea around1 on the floor of which much basic pumice-ash had been previously deposited4 ,such masses as they sank would lose most of their original momentum4 ,,remarkable ,,section ,,near ,,korolevu ,,hill4--,between the hills of ,korolevu and ,nganga-turuturu1 at an elevation of about #cjj feet above the sea1 there is a singular exposure of tuffs horizontally stratified and forming a low escarpment or line of cliff about #ae feet high on the hill-side4 ,these beds display the passage from basic tuffs below to relatively acid tuffs above1 and they establish that in this locality the period of acid andesites followed that marked by the eruption of basalts and basaltic andesites4 ,from their horizontal and undisturbed position1 it may be inferred that these deposits began to be formed under the sea when the activity of the submarine basic vents was on the wane4 ,in their composition and in the various degrees of coarseness of their materials1 we can plainly discern the history of volcanic action in this locality4 ,a hard compacted palagonite-tuff makes up the lower half of the thickness of beds exposed1 #ae feet in all4 ,the greater portion of it has the uniform texture of a sedimentary rock1 fine-grained below where the fragments are #a to #c mm4 in size1 and becoming coarser above where the larger measure #a to #b mm4 ,it is composed of more or less angular fragments of a basic vacuolar isotropic glass1 and of plagioclase and augite with much fine palagonitic dbris4 ,there is no effervescence with an acid2 but in the upper part there are a few casts of foraminifera of the 8globigerina0 type1 as indicated in the thin sections4 ,above this lies a bed of a similar basic tuff1 having however a banded appearance from the arrangement of materials of different degrees of coarseness1 the finer being #a-b mm4 in size1 the coarser #d-h mm4 ,there is little or no carbonate of lime2 but occasional tests of foraminifera of the type above mentioned occur in the slide4 ,the basic tuffs here abruptly terminate4 ,they represent the quiet deposition in water comparatively deep of the products of marine erosion1 and of the finer ejectamenta of some distant subaerial vent4 ,above the basic tuffs lie a series of tuffs1 about #e feet in thickness1 and composed mainly of the debris of acid andesitic rocks of the hornblende-andesite type1 such as occur in the ,ndrandramea district4 ,they mark a period of active eruption on the part of some neighbouring acid andesitic vent in this neighbourhood1 which the subsequent explorer may be able to identify with some volcanic 8neck40 ,these tuffs are composed partly of fragments of a hemicrystalline hornblende-andesite and partly of crystals1 broken and entire1 of plagioclase1 hornblende1 rhombic pyroxene1 and augite4 ,the plagioclase is tabular1 zoned1 and glassy1 and gives extinctions of oligoclase-andesine 7#f to #ab74 ,the hornblende is bottle green1 markedly pleochroic1 and gives extinctions up to #ad4 ,the rhombic pyroxene has the characters described on page #cja1 in the case of the ,ndrandramea rocks4 ,the augite is less frequent1 but the two pyroxenes are sometimes associated as intergrowths4 ,these acid tuffs do not effervesce with an acid1 nor can any tests of foraminifera be observed in them2 but since these organisms are represented in the basic tuffs below1 it is highly probable that the whole series of these horizontal beds is submarine4 ,the first or lowest bed of the acid tuffs indicates a somewhat violent volcanic outbreak in this neighbourhood1 following the deposition of the basic tuffs4 ,it is composed of loosely compacted subangular fragments1 #a to #c millimetres in size1 in which the macroscopic prisms of the rhombic pyroxene are especially frequent4 ,it passes upward without interruption into a regularly grained sandstone formed of rounded and subangular fragments measuring #c to #g mm4 across4 ,above this lies a quite distinct bed1 a few inches thick1 of a fine compact clay rock1 where the mineral fragments measure only #je to #ab mm4 in diameter1 hornblende being well represented1 although the rhombic pyroxene is very scanty4 ,up to this time these beds of acid tuffs indicate a gradual defervescence of the volcanic activity that began with some violence1 as shown by the characters of the lowest bed4 ,now another outbreak occurred1 and overlying the clay-like bed we find a coarse tuff made up of fragments #b to #e millimetres across1 and approaching in texture and appearance a subaerial tuff1 but in other respects similar to those below it4 ,it is the last and uppermost of this series of acid tuffs1 and with it terminates an interesting record of the past in this region1 the chief features of which may thus be summarised4 ,a prolonged period of quiet deposition of submarine basic tuffs1 the products partly of marine erosion and partly of distant eruptions1 was abruptly followed by the outbreak of a neighbouring vent during which tuffs formed of the debris of acid andesites were deposited4 ,the gradual decrease in the degree of activity is plainly shown in the gradual diminution in size of these tuffs1 until they acquire the fineness of a clay4 ,then another burst of activity from the same vent or vents occurred1 and the record ends4 ,since that time there has been apparently an upheaval to an elevation of #cjj feet above the sea4 ,as1 however1 the beds are quite undisturbed1 the emergence may have been due to the lowering of the sea-level1 a subject which is discussed in ,chapter ,,xxvii4 ,,coast ,,between ,,wailea ,,bay ,,and ,,lekutu4--,the hills here often approach the coast1 their spurs running down to the beach4 ,in the low range1 #bej to #cjj feet high1 east of ,wailea ,bay1 are exposed palagonite-tuffs dipping gently north-east and composed of fragments of a vacuolar basic glass1 more or less palagonitised1 and of minerals 7plagioclase1 etc47 not exceeding #b mm4 in size4 ,these deposits are apparently non-calcareous and show no organic remains4 ,farther along the coast towards ,nativi basic tuffs and agglomerates appear at the surface2 but the underlying rock1 exposed in position in the stream-courses and prevailing along much of the sea-border to ,nativi and a mile or so beyond1 is a vesicular semi-ophitic basaltic andesite with coarse doleritic texture and containing much interstitial smoky glass4 7,it belongs to the non-porphyritic group of genus #i of the augite-andesites described on page #bgc47 ,such rocks evidently represent ancient flows4 ,they give place as one proceeds east to porphyritic semi-ophitic doleritic rocks of the same genus and to semi-vitreous basic rocks4 ,about half a mile west of ,nukunase a vesicular doleritic basaltic andesite forms a spur protruding at the coast4 ,it is semi-ophitic and contains in the smoky glass of the groundmass little irregular cavities filled with a yellowish residual magma like palagonite in character4 7,it is referable to genus #ab of the augite-andesites1 described on page #bge47 ,a few paces west of this spur a vertical dyke1 #bj feet wide and trending ,n4,w4 and ,s4,e41 appears on the beach4 ,it is formed of a bluish scoriaceous basaltic andesite containing much glass in the groundmass and showing imperfectly developed felspar lathes4 ,it is included in genus #d of the augite-andesites described on page #bgj4 ,a little east of the spur there is another dyke apparently vertical and formed of a vesicular rather than a scoriaceous basaltic andesite referred to genus #a of the augite-andesites 7page #bfg74 ,it differs from the rock of the previous dyke in the presence of small plagioclase phenocrysts which contain abundant magma-inclusions2 but it resembles it in the characters of the groundmass4 ,this dyke is about #dj feet in thickness and trends ,n4,e4 and ,s4,w4 ,it may be inferred from the foregoing remarks that there was at one time a volcanic vent in the district west of ,nukunase4 ,the lines representing the trend of the two dykes above noticed would if extended meet at a common focus a little way inland4 ,the rocks of the dykes differ conspicuously from the prevailing doleritic rocks that form1 as before remarked1 the ancient flows1 the average length of the felspar-lathes in the former being #a-b mm41 in the latter #c-d mm4 ,both1 however1 belong probably to the same vent of which now the exact situation would not be easy to discover1 on account of the re-shaping of the surface through the denuding agencies4 ,,mount ,,koroma4--,the highest peak of the hills lying inland between ,wailea ,bay and ,lekutu is named ,koroma and attains a height of #a1chd feet4 ,i did not ascend its slopes higher than #ijj feet1 and approached it from the ,mbua or south side4 ,extensive plains1 covered with the usual 8talasinga0 vegetation1 reach inland from the shores of ,mbua ,bay to the foot of this range without attaining a greater elevation than #ajj feet4 ,this low district is drained by the ,mbua river and its tributaries1 the rock usually exposed at its surface being a decomposing porphyritic basaltic andesite4 ,it is again referred to on page #ef in connection with the low-lying level region of this portion of the island of which it in fact forms a part4 ,a basic non-calcareous fine-grained tuff-sandstone is exposed in a stream at the foot of the south slope of ,mount ,koroma4 ,whilst crossing some low wooded outlying hills in this locality1 ,i came suddenly upon what seemed like a desert in miniature1 quite bare of vegetation and occupying an area of some acres4 ,here a porphyritic basic rock1 from some cause unknown to me1 has decomposed in the mass to a depth of #bj feet and more2 and the result is a surface of white crumbling rock scored deeply by the rains and carved out by the denuding forces into miniature hills and dales4 ,it is not improbable that a small crater in its last solfatara-stage once existed here2 but the whitened disintegrated rocks alone remain1 and we can now only hazard a conjecture as to the cause4 ,i found a variety of basic rocks exposed on the hill slopes up to #ijj feet4 ,the most frequent of the deeper-seated rocks which occurred in mass at this elevation1 and as large blocks on the lower levels1 is a dark grey rather altered hypersthene-augite-andesite1 referred to genus #a of that sub-class as described on page #bhf4 ,the specific gravity is #bgc1 whilst the groundmass displays a little greenish altered glass4 ,another of the deeper rocks1 exposed #ejj feet up the slopes1 is placed in the same sub-class1 augite and rhombic pyroxene being porphyritically developed1 separately and as intergrowths4 ,the groundmass displays short stout felspars1 augite1 and a little altered glass4 ,the rock is therefore referred to the orthophyric order described on page #bij4 ,spec4 grav4 #bgh4 ,evidence of more recent surface lava-flows here exists4 ,in one place ,i came upon such a bed #ab feet thick1 compact in its upper half and slaggy or scoriaceous in its lower half4 ,the rock is an aphanitic augite-andesite 7spec4 grav4 #bgg7 and belongs to species ,b1 genus #af1 of the augite-andesites1 as described on page #bha4 ,its groundmass displays felspar-lathes in flow-arrangement with a little interstitial glass4 ,slaggy lava is not uncommon on these slopes4 ,one specimen beside me is a semi-vitreous form of the deeper hypersthene-augite-andesites of this range4 ,there appears to be better evidence of sub-aerial lava-flows on the lower slopes of ,mount ,koroma than ,i found in any other part of the island4 ,it should have been before remarked that one of these flows lies upon a bed of a hard reddish compact tuff1 which appears in the thin section as an altered palagonite-tuff1 containing fragments of minerals including both rhombic and monoclinic pyroxene1 but showing neither lime nor organic remains4 ,the larger fragments are #b mm4 in size4 ,it seems likely that this flow ran into the sea during the emergence of this part of the island4 ,the prevalence of rocks of the hypersthene-augite-andesite type in ,mount ,koroma distinguishes this range from the surrounding regions of olivine-basalts and basaltic andesites4 ,this district is well worth a detailed examination1 and perhaps the remains of a crateral cavity may yet be found4 ,,the ,,coast ,,between ,,naivaka ,,and ,,koro-,,ni-,,solo ,,at ,,the ,,foot ,,of ,,the ,,north ,,slope ,,of ,,the ,,sesaleka ,,range4--,basaltic andesites1 and olivine-basalts of the ,naivaka type occur on this coast4 ,a rock of more acid character1 light grey and much altered1 is exposed at the surface where the track crosses the headland projecting into ,ruku-ruku ,bay4 ,it is one of the propylites referred to in my description of the second genus of the augite-andesites 7p4 #bfi74 ,the felspars of the groundmass give the small extinctions of oligoclase2 and in this respect it differs from the other augite-andesites4 ,besides the altered plagioclase phenocrysts there is much microporphyritic augite but slightly changed4 ,calcitic and other alteration products occur in the interstitial glass4 ,,mount ,,sesaleka4--,this is the name of the highest peak1 #a1cgj feet1 of a remarkable ridge-shaped range1 which is very precipitous on the east and north-east sides1 where there is a sheer drop apparently of #ejj or #fjj feet1 whilst on the other sides the slope is more gradual1 especially on the north where there is a gentle descent to the sea4 ,the actual summit is bare1 rocky1 and narrow4 ,there is a curious native legend relating to a pond on the top of this hill4 ,from what ,mr4 ,wittstock tells me1 it seems probable that there is a spring near the summit4 ,close to the top are the remains of an old 8koro-ni-valu0 or war-town2 whilst numbers of shells of species of ,cardium1 ,cypra1 and ,strombus1 such as would be used for food1 lie about4 ,many years ago there was a prolonged siege of this stronghold1 which is referred to here as indicating that the defenders had some independent water-supply4 ,in ascending from ,koro-vatu on the west side basic agglomerates and agglomerate-tuffs were found exposed as far as half-way up4 ,in the upper half occurred at first fine-grained calcareous tuffs1 bedded and dipping gently down the slope1 composed of palagonite-debris1 mineral fragments and calcitic material and displaying a few macroscopic tests of foraminifera4 ,these tuffs became non-calcareous and coarser as one approached the summit4 ,a specimen obtained from the top is coarse-grained1 being composed of fragments of basic glass1 usually palagonitised1 much augite1 a little plagioclase and fresh olivine1 but no tests of foraminifera1 the size of the fragments being usually #e-ae mm4 ,massive rocks were rarely exposed on this side2 but half-way up in a stream course ,i came upon an exposure of a porphyritic olivine-basalt containing a fair amount of devitrified interstitial glass4 ,its specific gravity is #bhe and it is referred to genus #be of the olivine basalts 7page #bei74 ,i descended by a gentle slope to the north1 coarse basic tuffs and agglomerates containing amygdaloidal fragments being displayed on the surface4 ,in a stream at the foot1 close to ,koro-ni-solo1 were blocks of a heavy compact olivine-basalt with specific gravity #bif4 ,,district ,,between ,,mount ,,sesaleka1 ,,thombo-,,thombo ,,point1 ,,and ,,vatu-,,karokaro ,,hill4--,this is a broken country with several abruptly rising lesser hills4 ,starting from ,koro-vatu and crossing the ,thombo-thombo promontory1 ,i reached the coast of ,mbua ,bay near ,navunievu4 ,basic tuffs and agglomerates prevailed on the way1 the last containing blocks of a scoriaceous basaltic lava bearing olivine4 ,the massive rocks exposed belong in some cases to genus #ac of the olivine-basalts as described on page #bef1 being dark grey and having a specific gravity of #bhh1 and in other cases to genus #af1 species ,b1 of the augite-andesites when they are lighter in colour and have a specific gravity of #bgg4 ,in both cases the interstitial glass is scanty4 ,i ascended ,vatui1 one of the numerous small hills of the district4 ,it is #dej feet high and is capped by a bare mass of tuff-agglomerate1 #dj to #ej feet high and containing fragments of vesicular basic lava4 ,this mass is pierced by a dyke1 #ah inches thick1 which is inclined to the ,n4,,ne4 at a high angle of #fj or #fe degrees with the horizon4 ,this dyke is composed of a compact olivine-basalt which is remarkable for the prevalence of small augite prisms in the groundmass4 ,it is described on page #bfe under genus #dd of the olivine-basalts4 ,hand-specimens are magnetic and display polarity1 which is due1 as pointed out in ,chapter ,,xxvi41 to the exposed situation of the peak4 ,vatui in its characters is evidently typical of the other lesser hills around1 which1 as viewed from below1 possess bare tops and precipitous declivities of the same formation4 ,all the hills in the district including ,sesaleka are capped by these basic tuffs and tuff-agglomerates2 and doubtless as in the case of ,sesaleka these deposits are all submarine4 ,this is true also of ,vatu-karokaro1 a hill #fjj feet high1 overlooking ,mbua ,bay and about two miles east of ,sesaleka4 ,in the lower part of this hill is exposed a dark compact basaltic andesite1 referred to genus #ac1 species ,b1 of the augite-andesites 7sp4 gr4 #bhc71 whilst blocks of a black olivine-basalt 7sp4 gr4 #bia7 occur in the agglomerate of the summit4 ,these hills may all be regarded as 8volcanic necks0 or the stumps of volcanic cones1 probably submarine4 ,,the ,,dividing ,,ridge ,,between ,,the ,,mbua ,,and ,,lekutu ,,plains4--,a level rolling 8talasinga0 district intervenes between ,mbua ,bay and the dividing ridge4 ,the upper part of this ridge1 which attains a height of about #ejj feet above the sea1 is composed of a hard grey sandstone-like tuff1 effervescing feebly with an acid1 which on examination proves to be formed in great part of fragments1 #jg-a mm4 in size1 of a dark basic glass occasionally vacuolar4 ,the rest of the deposit consists of similar-sized fragments of plagioclase and other minerals1 and includes also a few tests of foraminifera of the 8,globigerina0 type4 ,the mass of the ridge1 however1 is composed of coarse tuffs and agglomerates of a different kind which have been covered over by the foraminiferous deposit just described4 ,thus there are exposed on the lower slopes1 tuffs and agglomerates of a basic pitchstone formed of a brown glass containing a few felspar and pyroxene microliths4 ,in the tuff the fragments are three to six mm4 in size and show evidence of crushing in situ1 the interstices being filled with debris of the same material more or less palagonitised1#cd but there is no carbonate of lime4 ,large masses of an agglomerate made up of blocks of an acid andesite occur higher up the slopes4 ,the component rock belongs to an unusual type of hypersthene-andesite1 specially noticed on page #big4 ,the interesting feature in this ridge lies in the testimony it affords that the extensive ,mbua and ,ndama basaltic plains1 on which ,i was unable to discover any submarine deposits1 were at one time submerged4 ,,the ,,mbua ,,and ,,ndama ,,plains4--,these rolling plains are a striking feature in the western end of ,vanua ,levu4 ,they have an arid barren look1 are clothed with a scanty and peculiar vegetation1 possess a dry crumbling soil often deeply stained by iron oxide1 are traversed by rivers without tributaries descending from the wooded uplands of the interior1 and in fact have well earned the name given to them by the natives of 8talasinga0 or sun-burnt land4 ,both ,seemann and ,horne have remarked on the ,south ,australian aspect of these regions1 which are characteristic of the lee and drier sides of the larger islands of the group4 ,covered for the most part with grass1 ferns and reeds1 these low-lying districts are dotted here and there with ,casuarinas1 ,pandanus trees and ,cycads1 whilst such other trees and shrubs as ,acacia ,richii and ,dodona viscosa1 add to the variety and peculiarity of the vegetation4 ,the origin of these 8talasinga0 districts is discussed in the last chapter4 ,the ,mbua and ,ndama plains form a continuous region extending three to five miles inland to the foot of the great mountain of ,seatura1 to the watershed between ,mbua and ,lekutu1 and to the base of ,mount ,koroma2 whilst it reaches along the sea border from the vicinity of ,navunievu about four miles west of the ,mbua ,river to beyond ,seatovo a few miles south of the ,ndama ,river4 ,their extent is defined in a general sense by the #cjj feet contour line in the map4 ,their elevation1 however1 above the sea does not generally exceed #bjj feet and is usually only #ej or #ajj feet2 but at the foot of ,seatura they rise to between #cjj and #djj feet4 ,whilst on the one side these plains form a continuation of the lower slopes of the great ,seatura mountain1 on the other side they are extended under the sea as the broad submarine platform1 the edge of which1 as defined by the #ajj-;fathom line1 lies eight to ten miles off the coast4 ,it is pointed out on page #cgb that this continuity of surface1 both supra-marine and submarine1 extends probably to the geological structure and that the submarine platform represents the extension under the sea of the basaltic flows of the plains4 ,the whole region of the plains is occupied by olivine-basalts and basaltic andesites1 such as are found on the neighbouring lower slopes of the ,seatura mountain4 ,they are as a rule much decomposed1 even at a depth of several feet below the surface4 ,typically1 they are neither vesicular nor scoriaceous1 and in this respect they possess the character of submarine lava-flows4 ,the rolling surface of the plain is varied occasionally by small 8rises0 or hillocks marking apparently some secondary cone1 of which the much degraded 8wreck0 alone remains4 ,here and there fragments of limonite1 approaching hmatite in its compact texture1 lie in profusion on the soil1 representing doubtless small swamps long since dried up1 some of which still occur in the hollows of the plain4 ,mingled with these fragments are often pieces of siliceous rocks and concretions1 such as are found in the other 8talasinga0 districts of the island1 the description of which is given on pages #abh1 #acb1 c4 ,i will now refer more in detail to some of the points alluded to in this short description of these plains4 ,with reference first to the compact limonite1 it should be remarked that it occurs on the surface either as fragments of hollow nodules two or three inches across1 or as portions of flat 8cakes0 half to one inch thick4 ,it is especially abundant in the district lying a mile or two on either side of the ,navutua stream-course between ,ndama and ,mbua4 ,here the subsoil is charged with ferruginous matter1 and the water of the series of stagnant pools in the bed of the stream is stained blood-red by iron-oxide1 a circumstance that has naturally given rise to native legends of a corresponding hue4 ,these fragments of iron ore1 which lie between #ajj and #aej feet above the sea1 represent the final stage of a process which is now no doubt in operation on the bottom of the neighbouring pools and small swamps4 ,their presence on the surface goes to indicate that this open country has been for ages a land-surface free from forest1 as it is in our own time4 ,in a similar manner1 the extensive disintegration of the basaltic rocks that form these plains affords evidence of the great antiquity of these 8talasinga0 plains in their present unforested condition4 ,the extent to which these rocks have weathered downwards is very remarkable4 ,between ,ndama and ,mbua they are decomposed to a depth often of eight or ten feet below the surface4 ,this is well exhibited in the sides of deep channels excavated by the torrents during the rains4 ,here the spheroidal structure is well brought out in the disintegrating mass1 all stages being displayed in the formation of the boulders that are scattered all over these plains4 ,in one locality1 near the lower course of the ,ndama river1 a thickness of #be feet of decomposed rock was exposed in a cliff-face4 ,in this case the rock was a porphyritic basaltic andesite1 the disintegrating process having affected the whole thickness of the large spheroidal masses with the exception of a hard central nucleus of the size of the fist4 ,in one of these nuclei by my side it is apparent that during the extension of the weathering process the phenocrysts of glassy plagioclase become opaque long before the groundmass is affected4 ,in this specimen the stage of disintegration as affecting the felspar phenocrysts is at least one and a half inches in advance of that affecting the groundmass4 ,this great disintegration of the basaltic rocks1 which as pointed out on page #fd is also in progress on the slopes of the adjacent spurs of ,mount ,seatura1 is more characteristic of the porphyritic basaltic andesites than of the olivine-basalts4 ,it is to the spheroidal weathering that we must look for an explanation of the rounded boulders so frequent in these districts4 ,it may also be inferred that the soil produced from this extensive decomposition of the rocks is often very deep4 ,at the ,wesleyan ,mission ,station at ,mbua1 on level ground nearly a hundred feet above the river1 a well has been sunk to a depth of #bj feet in soil of this description2 and away to the westward a similar thickness of soil produced by the same cause is in places to be observed4 ,coming to the characters of the basaltic rocks of the ,mbua and ,ndama plains1 it may be remarked that the prevailing rocks are the porphyritic basaltic andesites1 having a specific gravity of #bgg to #bha1 which are in most cases to be referred to genus #ac 7porphyritic sub-genus7 of the augite-andesites described on page #bgh4 ,they possess large phenocrysts of plagioclase and but little interstitial glass4 ,the other rocks are olivine-basalts with specific gravity #bhh to #bij and showing only a few small plagioclase-phenocrysts4 ,they display a little residual glass and belong for the most part to genus #cg of the olivine basalts described on page #bfb4 ,in both these basaltic rocks the felspar-lathes are in flow-arrangement2 but in the basaltic andesites they average #aa mm4 in length1 whilst in the olivine-basalts they average #ah mm4 ,the low mound-like 8rises0 in these plains1 to which previous reference has been made1 are not usually elevated more than #ej feet above the general surface4 ,one of these hillocks that lies near the track from ,mbua to ,navunievu1 about two miles from the ,wesleyan ,station1 is composed of a remarkable semi-vitreous pyroxene-andesite passing upward into a rubbly rock of the same nature4 ,the rock of this old volcanic neck is of an unusual type and is referred to the prismatic order of the hypersthene-augite andesites described on page #bhi4 ,both the felspar and pyroxene prisms of the groundmass are in flow-arrangement4 ,one of these mounds near the ,mbua ,wesleyan ,station is apparently formed of the decomposing basaltic andesite of the district4 ,on its surface are fragments of earthy limonite and siliceous rocks4 ,the rarity of submarine tuffs and clays on these plains is somewhat singular2 but in the occurrence of foraminiferous tuffs high up the slopes of ,sesaleka and on the crest of the ,mbua-,lekutu dividing ridge we have evidence of the original submergence of all these lower regions4 ,it is probable enough that the ages of exposure that have since witnessed the reduction of the solid basaltic rock to a crumbling mass several feet in depth were more than sufficient for the stripping off of most of the overlying submarine deposits4 ,such deposits are1 however1 common on the surface of the extensive 8talasinga0 plains that constitute much of the north side of the island4 ,,the ,,shell-,,bed ,,of ,,the ,,mbua ,,river4--,rather curious evidence of an emergence of a few feet and of a considerable advance of the delta of the ,mbua river in comparatively recent times is afforded by a bed of marine shells exposed in the right bank of this river1 about #bjj yards below the boat-shed of the ,wesleyan ,mission ,station and about two miles in a straight line from the sea4 ,this bed1 which is about a foot in thickness1 is exposed for a distance of #gj or #hj yards4 ,it slopes gradually seaward as one descends the river1 being raised two or two and a half feet at its upper end above the river level at low tide1 whilst at its lower end it is at about the water-level4 ,the river-bank is here #ae or #af feet high1 and is composed in its upper half of a fine gravel of volcanic rocks mixed with earth1 which below passes abruptly into a friable non-calcareous black mud-rock 7not bedded and looking like consolidated swamp mud71 in which the layer of shells is contained4 ,these shells are1 therefore1 covered by deposits1 #ac or #ad feet in thickness1 of which the upper eight feet are formed of gravel and earth1 and the rest of mud-rock4 ,they are evidently gathered together on the slope of an old mud-flat4 ,the shells are all large marine bivalves1 belonging to the genera ,ostra1 ,meleagrina1 ,cardium1 ,arca1 c41 no freshwater shells occurring4 ,they are often much decayed and have lost the ligaments4 ,the valves are generally separate2 but in some cases they are still in apposition1 the cavity being then filled with the same black mud in which the shells are embedded4 ,they lie about in all positions1 some vertical1 some horizontal1 and are often piled on each other4 ,in some cases large borers have perforated one or both of the valves2 and here and there valves may be noticed with smaller oyster-shells attached to the inner surface4 ,no vegetable remains were discovered with the exception of a single 8stone0 of the fruit of the ,sea tree1#ce which is common in these islands1 its empty almost indestructible stones occurring frequently in the drift stranded at the mouths of rivers4 ,at first sight one would look to human agency for the explanation of this shell-bed2 but many of its features are inconsistent with such a view4 ,if the shells had been originally collected by the aborigines for food1 the absence of those of marine univalves of the genera ,turbo1 ,strombus1 ,cypra1 c41 such as are much appreciated as food by natives1 is inexplicable4 ,the extent of the bed and its uniform thickness are characters that give no support to such an explanation4 ,it represents1 as ,i apprehend1 an ancient shell-bank formed on a muddy bottom in comparatively shallow water near the mouth of a river4 ,since that time the ,mbua ,river has cut through its old deposits1 and the margin of its delta is now two miles to seaward1 the intervening new land being formed of extensive mangrove-swamps in its lower part1 whilst nearer the shell-bed there is much level land raised a few feet above the sea1 on which the native town and different villages now stand4 ,the amount of emergence here indicated since the time when this bank of shells was forming under the sea does not probably exceed a couple of fathoms4 ,,lekumbi ,,point4--,this singular long and low promontory is between three and three-and-a-half miles in length and rather less than a mile in average width4 ,it is monopolised by mangroves1 except at the extremity where the swampy ground passes into the dry sandy soil occupied by the characteristic vegetation of coral beaches4 ,this terminal portion1 which is about a third of a mile in length and raised a couple of feet above high-water mark1 was originally a reef-islet4 ,the outer third of the cape1 however1 is cut off from the remainder by a narrow winding passage in the mangroves1 which being #be or #cj feet wide can be traversed by boats at and near high-water1 and is often used to shorten the journey down the coast4 ,the flowing tide rushes in at both entrances1 and when the tide is ebbing it finds its way out at both exits1 the passage presenting the readiest way of the filling and emptying of the interior swamps with the flow and ebb of the tide4 ,before explaining the origin of this low tongue-shaped promontory of ,lekumbi1 it should be observed that it lies on a long projecting patch of coral reef which is continuous with the neighbouring shore-reefs4 ,depths of seven and eight fathoms are found off the sides and of #aa and #ab fathoms off the end of the reef-patch4 ,this reef in its turn must have been built up on a submarine bank protruding from the coast4 ,such a bank may have originally been produced by the deposits brought down by the ,ndama ,river which finds an exit through the mangroves near the base of the cape4 ,with the exception1 however1 of the ,lekutu ,river1 none of the other ,vanua ,levu rivers have given rise to such tongues of land at their mouths4 ,i am more inclined to hold that the submarine shoal1 which underlies the present low cape of ,lekumbi1 indicates an old lava-flow from the great crateral valley of ,seatura1 opposite the mouth of which it lies4 ,traces of such flows are still to be found in that locality4 ,,chapter ,v ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,seatura ,,mountain4--,in my description of the profile of this part of ,vanua ,levu1 reference has already been made 7p4 #c7 to the great mass of this mountain which occupies five-sixths of the breadth of the island4 ,viewed from seaward it looks like a huge table-topped mountain-ridge1 and as such it is represented in the ,admiralty charts2 but when its true contours are distinguished it appears1 when defined by the #cjj-;feet level in the map1 as a somewhat rounded mass1 measuring #ab miles in length and #aj miles in breadth and attaining a maximum height of #b1hab feet4 ,seen from the deck of a passing ship it displays more or less regular volcanic slopes1 especially on the east1 where there is a gradual descent at an angle of #c or #d degrees for some #aj miles1 and on the north towards the ,lekutu lowlands4 ,it also shows a fairly regular descent towards ,mbua ,bay on the west4 7,see profile1 p4 #fb47 ,on the west side1 however1 there is a great gap in the mountain-mass 7the ,ndriti ,gap71 marking1 as ,i hold1 an old crateral cavity of large dimensions1 and now occupied by the ,ndama ,river and its tributaries4 ,the adjacent ,seatovo ,range to the southward obscures the profile of the mountain on the south2 and it is in fact not at all easy for this reason to get a view with all the slopes displayed4 ,it is only at times1 when viewed in its complete mass with uninterrupted outlines1 as from off the mouth of the ,ndreketi ,river to the north-east1 or when the symmetry of its long eastern slope is observed from ,wainunu ,bay that ,seatura displays itself as a gentle-sloped mountain-mass of the ,mauna ,loa type4 ,dense forest clothes the greater part of it1 except on the north and north-west1 where it lies within the limits of the scantily vegetated 8talasinga0 region4 ,illustration3 ,profile and ,geological ,section of the western end of ,vanua ,levu from the ,wainunu estuary across the summit of the basaltic mountain of ,seatura to the edge of the submarine platform off the ,ndama coast as limited by the #ajj-;fathom line4 ,the slopes of this mountain are deeply furrowed by river-valleys which radiate like the spokes of a wheel from its central elevated mass4 ,down its northern slopes flow the ,lekutu ,river and its tributaries and the principal tributaries of the ,sarawanga ,river4 ,the large western affluents of the ,wainunu ,river descend from its eastern side1 whilst the ,korolevu1 ,tongalevu1 and other small rivers flow south into ,wainunu ,bay1 and the ,ndama ,river drains its western slopes4 ,in all these cases1 excepting that of the ,ndama ,river1 the rivers have worn deep valleys into the mountain-mass1 valleys of denudation that represent the work of ages4 ,that of the ,lekutu is a deep cut almost into the heart of the mountain2 at ,nandroro in this valley1 which lies #f to #g miles inland and #hjj feet above the sea1 the hills rise steeply on either side of the river to an elevation of #a1ajj and #a1bjj feet and more4 ,some of the large tributaries of the ,sarawanga and the ,wainunu flow through gorge-like valleys #bjj to #cjj feet in depth4 ,on the western slopes north of the ,ndama river1 the mountain-side presents an alternating series of lofty spurs and deep broad valleys4 ,in fact1 all around ,seatura its slopes are deeply furrowed through the denudation and erosion of ages4 ,the rocks of this ancient volcanic mountain are almost all of the massive basic type1 and except at the mouth of the ,ndriti ,gap hardly ever display a scoriaceous character4 ,it is also noteworthy that no detrital rock1 whether agglomerate1 tuff1 or tuff-clay came under my observation4 ,the rocks exposed on the surface are mostly blackish brown olivine-basalts and porphyritic basaltic andesites1 the former much prevailing4 ,in the northern portion1 however1 grey olivine basalts of a different type occur4 ,in the great crateral hollow1 which ,i have named the ,ndriti ,gap1 are displayed numerous dykes formed of highly altered basaltic rocks that may be classed among the propylites4 ,the dense forest that clothes the greater part of this mountain offers many serious hindrances to geological exploration4 ,except in the northern portion1 views of the surroundings are very limited1 and one has often to rely mainly on the aneroid and the compass to obtain correct ideas of the contours and general configuration4 ,during most of the time spent in the southern part of the mountain1 my work was greatly impeded by heavy rains1 and from this cause and from the frequent necessity of following up the stream-courses and of crossing rivers in flood1 ,i was usually wet through all the day4 7a7 ,the ,eastern ,slopes of ,seatura4--,the basaltic flows1 of which this mountain is principally composed1 are best observed on the eastern side where the original volcanic slopes are preserved4 ,although the rivers have worn such deep valleys into the mountain sides1 it is however not often that any great exposure of rock occurs1 on account of the dense forest-growth over much of this region4 ,it is only occasionally that the columnar structure of these old basaltic flows is displayed4 ,it is especially well exhibited in the face of a waterfall1 distant about two miles in a straight line from ,tembenindio and elevated about #gjj feet above the sea4 ,here there is an exposure to the extent of #be feet of huge basaltic vertical columns1 four to five feet across1 and pentagonal in form4 ,the rock is a blackish basalt with scanty olivine and a specific gravity of #bhg4 ,it is referred to genus #be of the olivine-basalts which is described on page #bei4 ,micro-phenocrysts of plagioclase and a few of augite occur1 the olivine being mostly replaced by pseudomorphs4 ,the felspar-lathes of the groundmass average #ah mm4 in length1 and there is a little brown opaque interstitial glass4 ,boulders and fragments of a closely similar basalt1 with a specific gravity of #bi1 lie about on the surface in this region4 ,the ,seatura slopes here abut on the plateau of ,na ,savu1 formed largely of volcanic agglomerates1 to be subsequently described4 ,on the south-eastern slopes of the mountain between ,ndawathumi 7inland7 and ,korolevu 7at the coast71 somewhat similar basalts with scanty olivine are exposed 7sp4 gr4 #bhf-bia74 ,some of them show the felspar-lathes of the groundmass arranged in a plexus 7genus #be71 whilst others exhibit flow-structure 7genus #cg71 the average length of the lathes varying in different localities between #ae and #ba mm4 ,all display scanty residual glass4 ,on the shores of ,wainunu ,bay between the ,wainunu and ,korolevu rivers occur porphyritic basaltic andesites with a considerable amount of glass in the groundmass4 ,there is exposed on the right side of the mouth of the last-named river a highly basic variety of olivine-basalt with a specific gravity of #cjg4 ,it is referred to genus #ae 7described on page #beh71 which includes the most basic rocks in my collection4 ,there are in this rock no plagioclase phenocrysts and the felspar-lathes of the groundmass are relatively infrequent1 whilst olivine and augite occur in abundance4 ,there is little or no residual glass4 ,in the district of ,tongalevu blackish olivine-basalts and basaltic andesites of the usual character are found4 ,in the ,na ,suva range1 which lies two miles inland from the shores of ,nasawana ,bay and forms the southerly extension of the mountain1 a somewhat compact variety of olivine-basalt 7sp4 gr4 #bib7 prevails up to the summit1 #a1eej feet above the sea4 ,it is included in genus #cg of the olivine-basalts4 ,in the length of the felspar-lathes 7#ae mm47 it belongs to the ,seatura type of these dark basalts4 7b7 ,the ,western ,slopes of ,seatura4--,here overlooking the plains north of the ,ndama ,river the same olivine-basalts and porphyritic basaltic andesites occur4 ,the vegetation is of the scanty 8talasinga0 character1 and since there is little or no soil-cap the disintegration of the rocks has been very great1 often extending to a depth of #aj or #ab feet4 ,it is remarkable that this disintegration is most marked in the 8talasinga0 and similar scantily wooded districts of the mountain4 ,on the densely wooded eastern and southern sides where there is a thick soil-cap1 it is by no means so evident4 ,here on the western slopes have been carved out deep broad valleys and lofty spurs1 the last in their turn furrowed on their flanks1 without any apparent sufficient cause4 ,the shallow streams at the bottom of the valleys appear quite incompetent to produce such great erosion2 and doubtless these results are partly due to the action on the crumbling rock-surface of temporary torrents formed during the rains4 7c7 ,the ,northern ,slopes of ,seatura4--,here within the scantily vegetated 8talasinga0 region the conformation of the land is well displayed4 ,broad1 deep and nearly parallel valleys1 separated by level-topped spurs and occupied by the ,lekutu and its tributaries1 score the mountain's slopes4 ,the prevailing rocks are blackish-brown olivine-basalts and porphyritic basaltic andesites1 such as occur around the other parts of ,seatura2 but grey olivine-basalts also occur1 possessing opaque plagioclase-phenocrysts and looking like porphyrites4 ,they are essentially holocrystalline and are probably more deeply situated than the other basaltic rocks4 ,they are referred to genera #bf and #ch described on pages #bfa1 #bfc1 and have a specific gravity of #bge-bhc4 ,dark doleritic basalts distinct from all the others are exposed in places4 ,a good idea of this region may be obtained by following the road westward from ,tavua on the head-waters of the ,sarawanga ,river to ,wailevu on the westernmost tributary of the ,lekutu ,river1 a distance of about #f miles4 ,leaving ,tavua one at once begins to ascend and cross the long spur that descends from ,seatura and divides the valleys of these two river-systems4 ,on its slopes are exposed much decomposed blackish basalts possessing scanty olivine and showing large porphyritic crystals of plagioclase4 ,they have a specific gravity of #bhd and are assigned to the porphyritic sub-genus of genus #be 7page #bei74 ,at the summit1 #hjj feet above the sea1 occur blocks of a grey holocrystalline basalt with scanty olivine and semi-opaque plagioclase-phenocrysts referred to genus #bf and having a specific gravity of #bgf4 ,it appears to form the axis of the spur4 ,descending to the main ,lekutu ,river1 just below ,kavula1 where the elevation is about #cjj feet above the sea1 one observes exposed in mass in the river-bed a dark semi-ophitic doleritic basalt similar to the doleritic rocks without olivine prevailing on the coast between ,wailea ,bay and ,lekutu 7see page #ej71 but differing in the absence of felspar-phenocrysts4 ,it displays a considerable amount of opaque interstitial glass and is assigned to genus #ab of the augite-andesites 7page #bge74 ,the specific gravity is #bgh1 but there are a few minute irregular cavities in its substance4 ,on leaving ,kavula one crosses another of the ,seatura spurs at a level of #fej feet1 descending then into a smaller river-valley occupied by a tributary of the ,lekutu1 on the banks of which lies the village of ,nawai1 #cej feet above the sea4 ,then another spur is crossed at an elevation of #dej feet and the descent is made into the valley of the ,wailevu tributary of the ,lekutu4 ,crossing the valley1 which at the town of ,wailevu is elevated #cjj feet1 one rises to a height of #gjj feet and then descends into the ,mbua plains4 ,these three almost parallel valleys of the ,lekutu and its two tributaries are worthy of a detailed examination4 ,the rocks on the surface between ,kavula and ,wailevu vary in character4 ,nearer ,kavula there appears a blackish compact olivine-basalt 7spec4 grav4 #bhh71 showing a little microporphyritic plagioclase and belonging to genus #cg of the olivine rocks4 ,further on is exposed one of the holocrystalline grey olivine-basalts with porphyritic plagioclase-phenocrysts and specific gravity #bhc4 ,it belongs to the type described in genus #ch of the rocks on page #bfc4 ,nearer ,wailevu there occurs a blackish porphyritic basalt with scanty olivine and specific gravity #bha4 ,it contains but little residual glass and is referred to the porphyritic sub-genus of genus #be4 ,in some cliffs at the river-side close to ,wailevu1 there is displayed a semi-vitreous basaltic andesite1 showing large porphyritic plagioclase crystals1 #c to #h mm4 ,its low specific gravity 7#bfh7 is to be attributed to the large amount of glass in the groundmass4 ,there is a loose mesh-work of felspar-lathes1 but the augite is not differentiated4 ,westward of ,wailevu commence the decomposing basaltic rocks of the ,mbua plains4 7d7 ,traverse of the ,northern ,part of the ,summit of ,seatura from ,kavula ,south-,west to ,narawai4--,the track first lay up the picturesque valley of the ,lekutu ,river to ,nandroro1 #b miles distant and #hjj feet above the sea4 ,on the way blackish basaltic rocks of the prevailing ,seatura type1 with or without scanty olivine1 were displayed often in a decomposing condition4 ,at one place a characteristic grey olivine-basalt1 showing opaque porphyritic plagioclase 7sp4 gr4 #bhg71 and looking like a porphyrite1 was exposed4 ,on account of the abundance of the olivine1 it is placed in genus #b of the olivine-rocks4 ,after ,nandroro the path lay up the steep mountain-side to a height of #a1ejj feet3 and afterwards across the summit of the northern part of ,seatura1 which is here about two miles in breadth4 ,this elevated region is well wooded with here and there a patch of 8talasinga0 land2 but it is by no means level1 its elevation varying between #a1djj and #a1hjj feet1 and it soon became evident that we were crossing the heads of valleys1 sometimes #bjj or #cjj feet in depth1 that could only have been excavated by the torrential rains4 ,these streamless valleys afford another indication of the denudation to which this ancient mountain has been subjected4 ,the rocks prevailing in this elevated northern portion of ,seatura1 at heights of #a1ejj to #a1hjj feet above the sea1 are3 7a7 blackish basalts with scanty olivine1 a little interstitial glass1 and belonging to the porphyritic and non-porphyritic sub-genera of genus #be of the olivine-rocks3 7b7 grey olivine-basalts with porphyritic opaque plagioclase1 containing but little residual glass1 but varying greatly in the amount of olivine and belonging to the genera #b and #bf of the olivine-basalts2 they would be classed1 as far as appearance goes1 as porphyrites2 their specific gravity ranges #bhe to #bij4 ,the rock exposures were1 however1 scanty2 and but little information could be obtained of the mode of occurrence4 ,no scoriaceous rocks were found except in the instance of a compact dark basalt without plagioclase phenocrysts1 apparently a dyke rock1 and belonging to genus #dj of the olivine-basalts4 7e7 ,ascent to the ,summit of ,seatura from ,ndriti4--,the town of ,ndriti lies in the great gap in the south-west side of the mountain which has been previously mentioned as probably an old crateral cavity4 ,after traversing a district of highly altered basic rocks or propylites1 to be subsequently described1 and reaching an elevation of about #djj feet above the sea1 ,i came to the long slope that leads up to the summit4 ,a dense forest hid everything from view1 so that the compass and aneroid had alone to be relied on4 ,at first one traversed a series of step-like alternations of level ground and steep 8rises10 until the old site of the village of ,seatura1 about #a1bjj feet above the sea1 was reached4 ,there are some strange legends connected with this old mountain-village1 which is now only indicated by little piles of stones and the debris of a wall1 and was evidently abandoned long ago4 ,we finally reached the summit by following up a spur or ridge in a northerly direction from ,seatura4 ,there was a precipitous descent on either side of the ridge with evidently a broad1 deep valley to the eastward4 ,the summit was rounded2 but on account of the forest no view could be obtained4 ,there was never any extensive exposure of rock noticed during the ascent2 but all the way up occasional small blocks of a blackish olivine-basalt were observed on the surface1 of the same general type as that found all around the mountain and referred to genus #cg in the synopsis4 7f7 ,the ,ndriti ,basin or ,gap4--,this great hollow in the side of ,seatura1 which ,i have named after the town in its midst1 is apparently a crateral cavity now drained by the ,ndama river1 and its tributaries1 and covered with dense forest to such a degree that a general view of the whole is impracticable4 ,the glimpses1 however1 that one obtains of the mountain scenery are very grand1 the town of ,ndriti lying in the midst of mountains that rise almost on all sides of it except on the west4 ,this great cavity is contracted at its mouth a little below the town and expands in its interior1 where it must be two or three miles in width4 ,its floor is fairly level and is elevated only about #bjj feet above the sea2#cf whilst its mountainous sides rise to #b1jjj feet and over4 ,as shown in the map there are two breaks in the outline of this ancient crater1 the one on the west through which the ,ndama river flows1 the other on the south where the dividing ridge1 separating it from the ,nandi ,valley is under #gjj feet in elevation4 ,the ,nandi ,gorge1 as ,i will term the last-named1 is a narrow picturesque ravine leading through the mountains from ,nandi to ,ndriti4 ,one follows up a rocky stream-course hemmed in by precipitous sides until the top of the gorge is reached1 when the watershed is crossed1 and the descent is then made to ,ndriti by one of the tributary stream-courses of the ,ndama river4 ,two or three large rapid streams1 after draining its mountainous slopes1 unite within the basin to form the ,ndama river1 which1 as it issues from its mouth1 becomes a comparatively placid stream rolling sluggishly along to the sea1 some five or six miles away1 with an average drop of about thirty feet in a mile4 ,in the course of ages the original configuration of this great hollow has doubtless been extensively modified by the denuding agencies4 ,the rainfall on the mountain-slopes must be very great1 probably not under #bej inches in the year#cg2 and ,ndriti1 though only #bjj feet above the sea1 is in all probability on account of its situation one of the wettest places in the island4 ,the rivers have evidently been important factors in reshaping the original cavity4 ,nearly all the rocks exposed in situ in the beds of the rivers and streams in the floor of the great ,ndriti basin1 and for #cjj or #djj feet up its sides are more or less highly altered basic rocks1 to which the old and the new names of greenstone and propylite may be fitly applied4 ,they often sparkle with pyrites1 and not uncommonly effervesce with an acid1 so that one is apt to imagine one's self in a region of limestone4 ,the degree of alteration varies considerably1 those most altered being light-coloured and greenish1 whilst the others are darker1 the specific gravity ranging from #bfi to #bgi4 ,in spite of these differences almost all of them appear to belong to the same eruptive series1 being as a rule sharply distinguished from the prevailing unaltered surface basaltic rocks of the slopes of ,seatura by the size of the felspars of the groundmass1 which average about #c mm4 in length1 whilst those of the basaltic rocks just alluded to average only #ag or #ah mm4 long4 ,these rocks are also well displayed in the sides of the ,nandi ,gorge2 and from their mode of exposure by river-erosion1 as well as from their relatively coarse crystalline texture1 and from their alteration1 it may be inferred that they are older and more deeply situated than any of the ,seatura rocks before referred to4 ,whether these rocks1 which extend over an area of some square miles1 have been altered by solfataric action or contact-metamorphism1#ch ,i will not now say4 ,the fact remains1 however1 that they are best exposed wherever the streams have worn deeply into the floor1 and lower slopes of the great basin1 or have cut down into the mountain-mass as in the case of the ,nandi ,gorge4 ,the rocks that lie in loose blocks on the surface either at the bottom of the basin or on its slopes extending even to the very summit of the mountain 7see page #fg71 are characteristic blackish olivine-basalts of the type prevailing around the mountain's slopes4 ,these propylites are most frequently exposed as dykes in the beds of the rivers at the bottom of the basin4 ,such dykes vary from #d to #f feet in thickness1 and they are very conspicuous when they stretch across the river's breadth projecting more or less above the water4 ,from their frequency it may be inferred that in many other small exposures1 ill suited for displaying the mode of occurrence of the rock1 we have also to deal with dykes4 ,judging from four dykes that were particularly examined1 they are all vertical or nearly so1 and all run in much the same direction1 namely1 ,n4,n4,w4--,s4,s4,e4 or ,n4,w4--,s4,e41 whether on the north or south side of the great basin4 ,in one instance1 a rudely columnar structure across the thickness of the dyke was observed4 ,from their exposure in river-beds it was rarely possible to ascertain much more than is given above4 ,however1 in the bed of a river1 a mile above ,ndriti1 there was an extensive exposure of a highly altered greenish rock which was crossed by a vertical dyke1 #d feet thick1 formed of a dark grey less altered rock4 ,i have referred these two propylites to two different genera of the augite-andesites1 the dyke-rock to genus #b1 and the other to genus #d4 ,in the case of the dyke the rock is a little vesicular2 whilst in the other it is densely charged with pyrites4 ,both have been subjected to the same alteration2 but in a different degree2 and it would thus seem that solfataric influences were here in operation before and after the intrusion of the dyke4 ,with reference to the characters of the alteration of these rocks of the ,ndriti basin1 it may be remarked that where the change is greatest the felspars of the groundmass are alone recognisable4 ,the plagioclase phenocrysts are quite disguised by alteration products1 and chlorite1 viridite1 epidote1 calcite1 pyrites1 c41 occupy much of the groundmass4 ,other rocks are less affected and in a few the change is only slight4 ,with regard to the prevailing types of the propylites of the ,ndriti ,basin1 it has already been observed that in most of them the felspar-lathes of the groundmass are unusually large1 the average length being #c mm4 ,from the rare occurrence of olivine in some of the rocks that are but slightly changed1 it is to be inferred that most of them belong to the augite-andesites1 and might be termed doleritic basaltic andesites4 ,but in other respects they differ considerably1 both as regards the presence or absence of flow-arrangement of the felspar-lathes1 and in the occurrence and size of the plagioclase-phenocrysts1 some having large porphyritic crystals1 others small phenocrysts1 and others none at all4 ,many of them contained a little interstitial glass4 ,in my classification of the augite-andesites they are assigned to genera #b1 #d1 #af1 c41 and additional particulars concerning their characters are given in the description of those genera4 ,judging from the average large size of the felspar-lathes it may be held that1 although in other features they often differ1 some of the general conditions under which they were produced were the same4 ,on the right bank of the ,ndama river1 opposite ,ndriti1 there is a singular association of a vertical dyke of a bluish-grey basic andesite with a reddish scoriaceous lava1 apparently a flow4 ,the dyke is about #d feet thick and runs ,n4,w4 and ,s4,e41 like the other dykes of the basin1 exhibiting also a rudely columnar structure across its breadth4 ,where the two rocks are in contact1 the dyke has a vitreous border half an inch thick1 and an offshoot of the dyke1 four inches wide1 has penetrated the lava1 acquiring at the same time a more glassy texture4 ,the small size of the felspar-lathes of both rocks distinguishes them from the dyke rocks of the basin1 where the felspars are twice as long4 ,both rocks show some degree of alteration4#ci ,in following the valley of the ,ndama ,river from ,ndriti to ,telana1 about three miles farther down1 one traverses a picturesque region4 ,emerging from the great basin the river flows through the rolling plains of the 8talasinga0 district4 ,near ,ndriti1 and occasionally on the way to ,telana1 is exposed a scoriaceous grey basaltic rock2 and between two and three miles below ,ndriti there is to be observed in the river-bed evidence of a comparatively recent flow of a highly basic scoriaceous lava from the ancient crater of the ,ndriti basin4 ,the rock1 which is dark and fresh-looking1 shows large porphyritic crystals of augite and olivine but no plagioclase1 whilst the groundmass contains a little brown interstitial glass4 ,its characters will be found described under genus #c of the olivine-basalts 7p4 #bee74 ,its specific gravity1 notwithstanding its large empty steam-pores1 is #bia4 ,it differs markedly from the basaltic rocks of the ,seatura slopes and the ,mbua and ,ndama plains1 in the great porphyritic development of augite and olivine1 in the large size of the felspars and augite of the groundmass1 and in its numerous steam-holes4 ,but in the coarseness of its small felspars it belongs to the same type as the altered or propylitic basic rocks of the ,ndriti basin4 ,it is probably by some such lava flow from the old ,ndriti crater that the submarine bank was formed off the adjacent coast on which the low ,lekumbi promontory has been built up4 ,in the numerous dykes of the ,ndriti basin and in the great alteration which their rocks have frequently undergone1 we have evidence in support of the view that this is an old crateral cavity1 an opinion that is supported by the indications of lava-flows that have issued1 apparently in later times1 from the mouth of the basin4 ,reference has already been made to the locality where a dyke-rock and the rock-mass1 into which it has been intruded1 are both propylitic2 and from this and other facts1 such as the varying degrees of alteration in different parts of the basin1 it is to be inferred that in the last stage of the activity of this vent its bottom and sides were extensively affected by solfataric influences4 ,since that period1 the configuration of the crater-basin has been greatly modified through the denuding agencies4 ,the absence1 or at least the great rarity1 of tuffs and agglomerates in the case of ,seatura is remarkable4 ,the mountain has evidently been built up in the mass by flows of basic lava2 and from this source have no doubt in an important degree been derived the basaltic flows of the ,ndama1 ,mbua1 and ,sarawanga plains1 great streams of basalt that further seaward have helped to form the submarine platform extending several miles from the coast4 ,the submarine tuffs and agglomerates that occur at various elevations1 reaching as high as #a1bjj feet above the sea1 in the ,sesaleka1 ,lekutu1 ,sarawanga1 and ,ndrandramea districts lying to the north-west1 north1 and east1 did not come under my notice on the ,seatura slopes4 ,on the other hand1 except in the few localities1 where scoriaceous rocks occur1 the general type of the basalts is such as we would expect to find in submarine flows4 ,in no part of the island1 however1 is the antiquity of the land-surface so well attested by the disintegration of the basaltic flows1 which extends here to depths of ten and even twenty feet4 ,this is in favour not only of the sufficiency of time1 but also of the ability of the denuding agencies to strip off the surface-deposits4 ,however this may be1 it is evident that the mountain of ,seatura possesses a history quite independent of that of the rest of the island4 ,i have pointed out in ,chapter ,i4 that it represents a mountain of the ,tahitian type4 ,in its radiating valleys and in its basaltic character it much resembles the mountainous island of ,tahiti1 which ,dana describes as a gently sloping cone of the ,hawaiian order that through the erosion of ages has become a dissected mountain4#dj ,,the ,,seatovo ,,range4--,this remarkably situated mountain-range1 which ,i have named after a town at the foot of its western slope1 extends from the valley of the ,ndama ,river to ,solevu ,bay4 ,it attains a maximum height of about #a1hjj feet1 and varies between this elevation and #a1ejj feet until in the vicinity of ,solevu1 where it descends as a mountainous headland to the coast4 ,its summit is narrow and ridge-shaped1 and although the whole range is not interrupted by gaps it has a composite origin4 ,at its north end1 where it is cut off from the ,seatura ,range by the ,nandi ,gorge it helps to close in the large ,ndriti basin4 ,towards the south an offshoot proceeds eastward and shuts in ,solevu ,bay4 ,but1 although apparently all the rocks are basic1 considerable variety prevails1 and there are many puzzling points in the geological structure of this region4 ,at the place where this range abuts on the ,ndama valley1 below ,ndriti1 the grey scoriaceous basalt1 before referred to1 is exposed at its foot4 ,however1 the usual blackish basaltic rocks1 often carrying a little olivine1 form in mass the mountainous southern headland that culminates in ,solevu ,peak 7,ulu-i-matua72 and the same rocks prevail in the lower regions on the west side of the range from ,vuia ,point to the valley of the ,ndama ,river4 ,the southern portion will be described in the account of ,solevu ,bay2 and ,i will now give the results of my journey across the summit of the range about half a mile south of the ,leading ,peak of the chart4 ,the eastern slopes are steep and often precipitous1 whilst on the western side there is a more or less gentle descent to the lower levels1 suggestive of a volcanic slope2 and it is remarkable that whilst the rocks exposed on the precipitous eastern side for the lower two-thirds are sometimes markedly altered1 on the western side they are comparatively unchanged4 ,these facts at once suggest that we have here the western rim of a large crateral cavity1 though the topography of this district is not sufficiently well shown in the chart to enable one to define its original limits4 ,this inference is also supported by the occasional scoriaceous character of the rocks below referred to4 ,the most frequent rocks in the upper two-thirds of the range are grey porphyritic olivine-basalts1 displaying opaque plagioclase phenocrysts and more or less hematised olivine1 the specific gravity being about #bi4 ,they approach in characters the grey porphyritic olivine-basalts of the northern part of ,seatura 7pages #fe1 #ff72 but differ amongst other features in the greater abundance of the olivine and in exhibiting flow-structure4 ,they are usually almost holocrystalline1 and are assigned for the most part to genus #ad of the olivine-basalts4 ,they are extensively exposed in the stream-courses on the west side between #ejj and #ijj feet2 and huge masses of the same rocks1 but containing less olivine and more glass1 and displaying much calcite1 viridite1 and other alteration products1 are found near the base of the eastern slopes4 ,the semi-vitreous condition of these rocks is represented in the large masses of a dark very scoriaceous porphyritic lava1 possessing quite a cindery appearance1 that occur on the narrow ridge-shaped summit4 ,the groundmass shows a few scattered felspar microliths2 but it is in the main composed of a dark opaque glass4 ,small cube-like crystals of chabazite line some of the cavities4 ,other basic rocks are not infrequent and apparently represent dykes4 ,thus on the eastern side at #hjj feet is exposed a dark-grey semi-ophitic doleritic rock 7sp4 gr4 #bgg7 assigned to genus #ab of the augite-andesites 7page #bge74 ,the felspar-lathes average #c mm4 in length1 and there is a little interstitial glass containing viriditic and calcitic alteration products1 the same materials filling small rounded vesicular cavities4 ,on the same slope between #a1jjj and #a1bjj feet1 there are displayed fresh-looking compact non-porphyritic basaltic andesites 7sp4 gr4 #bhd71 where the felspar-lathes average #b mm4 and the interstitial glass is scanty4 ,they are referred to genus #af1 species ,c1 of the augite-andesites4 ,on this side also between #fjj and #hjj feet occur blocks of a highly altered slightly vesicular augite-andesite showing a little microporphyritic plagioclase4 ,it is assigned to genus #ac1 species ,b1 of the augite-andesites4 ,in one place where it is in position it is scoriaceous1 the steam-holes being round1 empty and one to five mm4 in size4 ,in the less glassy rock it displays numerous small irregular cavities either filled with fibrous viridite or calcite or showing concentric zones of the two minerals4 ,the felspar-lathes are #ae-b mm4 in length4 ,in blocks near the foot of the eastern slope occur a blackish olivine-basalt 7sp4 gr4 #bhh7 of the prevailing ,seatura type1 possessing a little interstitial glass and felspar-lathes with an average length of #b mm4 ,it belongs to genus #be of the olivine-rocks4444 ,on the western slopes at a height of #ejj feet occurs a dark compact rock 7sp4 gr4 #bhi7 with abundant olivine which is referred to genus #a of the olivine basalts4 ,there is a little residual glass1 the felspar-lathes averaging only #jh mm4 in length4 ,a similar-looking rock is exposed at #a1djj feet1 which displays felspar-lathes averaging #b mm4 long 7sp4 gr4 #bi74 ,it belongs to genus #cg of the same olivine class4 ,here also is assigned an aphanitic basalt1 with a few scattered large plagioclase phenocrysts and felspar-lathes averaging #ae mm4 long1 which is displayed near the base of the slope4 ,i could not satisfy myself as to the presence of tuffs on the slopes of this range4 ,some fine argillaceous rocks exposed half-way up on either side show no lime and contain no organic remains4 ,one specimen beside me is certainly a disintegrated basic rock4 ,no agglomerates came under my notice4 ,in the absence or rarity of detrital rocks this part of the range resembles the adjacent mountain of ,seatura4 ,although olivine-basalts prevail in this part of the ,seatovo ,range there is great variety in their characters2 and it does not appear possible to explain such a diversity except to assume that we have here an old crateral ridge which has again and again been penetrated by dykes and has since been greatly denuded4 ,we have here one of those singular mountain-ridges that characterise the central portion of the island1 but differing in this respect that the submarine tuffs and agglomerates1 which there occur on the surface1 even in the higher levels1 are here absent4 ,,solevu ,,bay4--,there are few localities in the island where so many kinds of basic rocks are displayed as around ,solevu ,bay4 ,in addition to the prevailing blackish porphyritic basalts and basaltic andesites1 there are grey porphyritic basalts1 grey non-porphyritic basalts1 black basalts with abundant large crystals of olivine1 c41 all of which have their distinctive characters4 ,this picturesque bay is surrounded by hills4 ,on the west side it is inclosed by the promontory forming the southern extension of the ,seatovo range which1 culminating in ,ulu-i-matua1 or the 8,head-of-the-,strong0 peak1 descends at first steeply and then gradually to the coast1 where it projects as ,vulavulandre ,point4 ,on the east side is a broken line of hills1 of which ,koro-i-rea1 the hill known to the natives as the 8,town of the ,albinos10 is the most conspicuous4 ,beyond it stretches the eastern point of the bay1 which the ,fijians call 8,ua-nguru10 that is1 8the noise of the waves40 ,on the shores lie the village of ,nawaindo1 8the running-stream10 and the once populous town of ,solevu1 which has given its name to the bay4 ,solevu1 as its name indicates1 is the place of the 8great assembly40 ,in the background rises the three-peaked mountain of ,koro-tolutolu1 8the three towns10 which forms a continuation inland of the eastern arm of the bay1 and joins the ,seatovo ,range at the head of it4 ,between these two ranges inclosing the bay lies the valley of ,solevu1 down which descends the ,solevu ,river to the sea4 ,in ascending this valley from the shore1 one rises only about #ajj feet above the sea for the first mile or two4 ,the promontory1 which in the even-topped ,ulu-i-matua or ,solevu ,peak1 attains a height of #a1ajj feet above the sea1 displays on its summit and on its eastern slopes descending to the ,solevu river1 and on its western slopes reaching down to the coast at ,vuia1 more or less porphyritic blackish olivine-basalts of the usual type with specific gravity #bhh-bij4 ,these basaltic rocks contain scanty olivine and only a little interstitial glass4 ,the felspars of the groundmass vary in different localities from #aa to #ae mm4 in average length4 ,the rocks belong to genus #cg of the olivine class which is described on page #bfb4 ,they are in the lower regions often decomposed to a considerable depth1 the spheroidal structure being well displayed during the weathering process4 ,where this promontory terminates in the low ,vulavulandre point1 these rocks give place in part to grey porphyritic olivine-basalts1 with specific gravity #bgi-bhc1 which from the abundance of the macroscopic opaque felspar look like porphyrites4 ,they come near to the rocks exposed on the north slopes of ,seatura and in the ,seatovo ,range4 ,at the end of the point they become scoriaceous and more vitreous2 but with this exception they contain but little glass4 ,they vary somewhat in character and are referred to genera #b and #ch of the olivine-class4 ,the prevailing rock in the interior of the ,ua-nguru promontory to the south of ,koro-i-rea is the blackish porphyritic basalt1 containing a little olivine1 and often much decomposed2 but at the point and on the east shores of ,solevu ,bay1 there is a considerable variation in the character of the basic rocks1 of which the two following are the most conspicuous4 ,near the village of ,nawaindo1 there is an apparent intrusion of a black lava-like basalt of high basicity 7specific gravity #cja7 showing abundant large olivine crystals1 five or six mm4 across1 with some porphyritic augite1 but no macroscopic felspar4 ,at the point the rock is somewhat scoriaceous1 with calcite occasionally filling the cavities1 whilst the olivine is so thoroughly hmatised that it glistens like brown mica4 ,the compact rock contains a little devitrified interstitial glass1 the felspar-lathes being unusually small1 their average length being only #jg mm4 ,it belongs to genus #ae1 the most basic of the genera of the olivine class represented in the island4 ,the second rock to be noticed is a slightly altered compact basalt without olivine forming apparently a dyke near the coast about half way between the village of ,solevu and ,ua-nguru ,point4 ,it has a specific gravity of #bhd1 the felspar lathes 7#ae mm47 presenting a marked flow-arrangement1 whilst there is a fair amount of altered residual glass in irregular spaces1 a millimetre in size4 ,the rock1 on account of its joint-structure1 could be easily worked as a building-stone4 ,it is referred to genus #af1 species ,b1 of the augite andesites4 ,the hill of ,koro-i-rea1 which rises on the east side of the bay to a height of #hej feet1 has a ridge-shaped summit4 ,its upper half is composed of a bluish-grey rock looking like a phonolite and usually compact1 except at the top of the hill1 where it is a little scoriaceous4 ,it has1 however1 a specific gravity of #bia or #bib1 and is in fact a pretty grey olivine-basalt studded with small olivine crystals about a millimetre in size and showing no other phenocrysts4 ,this type of olivine-basalt occurs also at ,ulu-i-ndali on the east side of ,wainunu ,bay1 but is rare in the island4 ,it differs amongst other features from the porphyritic olivine-basalts of the northern part of ,seatura and of the ,seatovo range in the absence of plagioclase phenocrysts4 ,there is apparently no interstitial glass1 whilst the average length of the more or less parallel felspar-lathes is #ac mm4#da ,on the lower slopes of the hill the common blackish porphyritic basalt or basaltic andesite is exposed4 ,in the grey-basaltic upper portion of this hill we have probably an old volcanic 8neck40 ,following the line of hills inland from ,koro-i-rea1 we cross the intervening saddle #dej feet above the sea1 and ascend the slopes of ,koro-tolutolu1 a ridge-shaped mountain backing ,solevu ,bay1 and having1 as its name indicates1 three peaks1 of which the highest is #a1bhj feet above the sea4 ,my observations indicate that this mountain is formed in mass of the common blackish-basalts described under genus #cg1 their specific gravity being #bhh to #bid4 ,but ,koro-tolutolu has also the peculiarity that it appears to be in mass magnetic4 ,the rocks obtained from its summit1 half-way up its western slopes1 and near its foot on the same side1 all display polarity1 a character also of the rocks of the neighbouring hills of ,ulu-i-matua and ,koro-i-rea1 but in their cases seemingly confined to the higher levels4#db ,neither tuffs nor agglomerates came under my notice at ,solevu ,bay4 ,this appears to be an ancient corner of the island1 from which denudation has stripped off nearly everything that could guide us in speculating as to its past4 ,although the hills of ,koro-i-rea and ,koro-tolutolu doubtless represent old volcanic necks1 the relation of ,ulu-i-matua to the very differently composed northern part of the same range1 as described on page #gc1 is extremely puzzling4 ,then again in the opposite sides of ,solevu ,bay we see exposed the remains of lava-flows that bear no relation to the present configuration of the surface4 ,we may suspect1 however1 that most of the volcanic energy was displayed under the sea4 ,,nandi ,,bay4--,lying north of ,solevu ,bay1 this bay is situated between spurs1 descending to the coast from the mountainous interior4 ,the valley extends a long distance inland without much change of level1 the elevation #a miles from the coast being not over #ajj feet above the sea4 ,at its head is the ,nandi ,gorge1 which leads into the ,ndriti ,basin1 the great crateral cavity of ,seatura4 ,there are some remarkable lofty1 isolated hills in this valley that would be well worth examining4 ,that the bay represents the site of an old volcanic centre is indicated by the occurrence on the shore of two basaltic dykes1 one on either side of the village of ,na ,savu and #cjj to #djj yards apart4 ,the eastern dyke is perhaps #cj feet thick1 whilst that to the west is scarcely half this thickness4 ,they exhibit an imperfect columnar structure1 the columns1 which are #f to #ab inches across1 being inclined at an angle of #ae or #bj from the vertical in such a way that it may be inferred that the molten material was ejected from some subterranean focus lying to the northward 7or inland7 at an angle of #ae or #bj above the horizon4 ,the basalt is a compact bluish-black rock with specific gravity #bie-bii4 ,it contains abundant olivine but no other phenocrysts and very scanty interstitial glass1 whilst the felspar-lathes average #a mm4 in length4 ,it is referred to genus #af of the olivine basalts1 and is remarkable for the flow arrangement not only of the felspar-lathes but also of the smaller olivine crystals4 ,blackish basaltic rocks of the prevailing type are exposed on the surface of the broad spur1 not over #ejj feet in height1 that divides the ,nandi and ,nasawana valleys and descends to the coast between the two bays thus named4 ,they belong to genus #cg of the olivine-basalts and display a few small plagioclase phenocrysts4 ,the felspar-lathes average #b mm4 in length1 and there is a little interstitial glass4 ,entering ,nasawana ,bay we find ourselves on the southern slopes of ,seatura1 of which the high ,na ,suva range that backs the bay is the southern extension4 ,,the ,,table-,,land ,,of ,,na ,,savu4--,this remarkable plateau has an elevation varying usually between #gjj and #hjj feet above the sea and a maximum breadth of four or five miles4 ,it is an area of basic agglomerates and basic tuffs and lies in the hollow between the basaltic mountain of ,seatura and the acid andesitic hilly region of ,ndrandramea4 ,for the convenience of description ,i have named it after the picturesque falls of ,na ,savu#dc at its southern edge4 ,these falls are celebrated in ,fijian tradition2 and from the brink in old time the native desirous of ending his life leapt into the gorge below4 ,after flowing sluggishly along on the surface of the table-land1 the ,mbutu-mbutu ,river arrives suddenly at the edge of a line of cliffs of volcanic agglomerate1 that here form the southern border of the plateau1 and with a volume #cj to #dj feet across1 it plunges down into the ravine #aej feet below4 ,as shown in the view from the gorge below1 there is a break in the middle of the descent4 ,these falls1 however1 are not easily accessible4 ,they are best approached by proceeding from ,wainunu to ,ndawathumi and thence up the gorge of the ,mbutu-mbutu ,river4 ,the surface of the plateau of ,na ,savu is densely wooded4 ,in places it is marshy1 and here thrives the ,giant ,sedge 7,scirpodendron costatum74 ,the ,makita tree 7,parinarium laurinum7 also flourishes in the wet districts2 and in the drier localities occur the ,ndakua 7,dammara vitiensis7 and the ,ndamanu 7,calophyllum-burmanni7 together with a palm of the genus ,veitchia4 ,here on this level watershed between the basins of the ,wainunu and ,sarawanga rivers1 the sluggish streams flow aimlessly along in but slightly eroded channels2 and it is not always possible to determine the side of the island to which they ultimately direct their course4 ,in their beds are pebbles and irregularly formed concretions of an impure reddish flint which ,i have described on page #ced4 ,on the north and south sides the table-land is much excavated by the tributaries of the ,sarawanga and ,wainunu rivers4 ,on the west where it meets the foot of the ,seatura slope portions of columns of basaltic rocks appear on the surface1 and deep gorges are worn by the large streams descending from the mountain4 ,on the east towards ,nuku-ni-tambua and ,tambu-lotu1 the surface is also much cut up4 ,the preservation of this table-land in a region1 where the denuding agencies are very active in their operations all around it1 is to be attributed to its being a level watershed1 where the head-waters of the ,wainunu and ,sarawanga rivers in part take their rise but have little or no eroding power4 ,it is not easy to obtain a good general view of the district of the falls on account of the dense forest-growth4 ,when making the traverse from ,tambu-lotu to ,ndawa-thumi1 it is observed that there is here a singular hollow1 about half a mile in length1 which receives the falls at the western end4 ,the river crosses this hollow and is at once received into the gorge below1 but there is no stream to explain the origin of the cavity4 ,on its north side the cliffs of agglomerate rise to a height of #aej to #bjj feet from their base1 but on the south the sides are much lower4 ,here there seem to be the remains of the crater of the ancient vent from which all the tuffs and agglomerates of the district were derived4 ,we must look for their origin in the vicinity1 and the only evidence of a crateral cavity is this streamless hollow extending east from the falls of ,na ,savu4 ,with reference to the basic tuffs and agglomerates of this plateau it may be observed that they cover the massive basic rocks and are probably not over #ajj or #aej feet in maximum thickness4 ,they are well exposed where the streams cut into the borders of the plateau4 ,the tuffs are sometimes bedded and slightly inclined1 and they may be fine or coarse grained4 ,they are more or less palagonitised hyalomelane-tuffs1 being composed mainly of fragments of a basic glass1 often finely vesicular and even fibrillar1 the vacuoles being filled with different materials1 whilst the palagonitisation is well advanced4 ,sometimes they have a brecciated appearance1 and in that case when the alteration of the basic glass is very extensive we find angular fragments1 #a to #b inches across1 of a greenish palagonite imbedded in a pale matrix of palagonitic debris1 the whole rock having a soapy feel and a steatitic appearance4 ,this is well shown on the sides of the stream-course at ,ndawathumi which lies at the border of the table-land4 ,these tuffs effervesce but slightly with an acid4 ,the basic agglomerate is displayed in the face of the falls and in the gorges4 ,the blocks are as a rule composed of semi-vitreous basaltic andesites of varying type1 showing no olivine and containing a fair amount of smoky glass in the groundmass4 ,at times they are scoriaceous and display amygdules of calcite or a zeolite4 ,in places the rock shows large phenocrysts of plagioclase and a semi-ophitic groundmass1 when it is referred to the porphyritic group of genus #i of the augite-class4 ,in a few of the scoriaceous blocks the augite of the groundmass is for the most part prismatic and rarely granular 7genus #e74 ,the massive rocks underlying the agglomerates in the vicinity of ,na ,savu are aphanitic augite-andesites1 differing in important characters from the rocks of the agglomerates4 ,they probably represent ancient lava flows of the ,na ,savu vent4 ,they are compact 7sp4 gr4 #bgb-bgf71 and display a groundmass formed of a felt of felspar-lathes1 averaging #je or #jf mm4 only in length1 and in flow-arrangement4 ,that occurring just below the falls is almost aphanitic1 but is referred to genus #ac1 species ,a1 sub-species a1 of the augite-andesites4 ,the rock from the gorge below is of the same character1 but on account of its opaque plagioclase phenocrysts it is referred to genus #ad1 and is described on p4 #bgi4 ,in one place on the plateau a tuff-agglomerate is penetrated by veins1 a few inches thick1 formed apparently of a finely brecciated tuff of basic glass fragments in a palagonitic matrix4 ,it is1 however1 pointed out on p4 #cdj that they were originally veins of basaltic glass which have been subjected to crushing1 and that the palagonite has since been produced4 ,in concluding this description of the table-land of ,na ,savu1 it may be inferred that the source of its basic tuffs and agglomerates is to be found in the same locality2 and probably the original vent is now represented by the hollow extending eastward from the falls4 ,with the exception of a large block of silicified coral found in the vicinity of ,ndawathumi and of the impure flints of the surface of the plateau1 which are described on pages #ced1 c41 no direct testimony of its submarine origin offered itself to me4 ,the palagonitic characters of the tuffs afford1 however1 indirect evidence in this connection2 and indeed the occurrence of submarine tuffs and limestones in the vicinity of ,tembenindio on its lower northern slopes 7see page #aca71 and the existence at elevations of several hundred feet above the sea of fossiliferous tuffs and clays in the ,wainunu and ,ndrandramea districts to the eastward1 afford strong presumptive evidence that the tuffs and agglomerates of the table-land were deposited under the sea1 and ,i may add in a period subsequent to that of the formation of the great basaltic flows of ,seatura and ,wainunu4 ,,chapter ,,vi ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,basaltic ,,plateau ,,of ,,wainunu4--,this table-land extends for a distance of seven miles from the base of the ,ndrandramea mountains in the heart of the island1 where it is elevated #a1ajj to #a1bjj feet above the sea1 to the valley immediately north of the hill of ,ulu-i-ndali1 where within a short distance of its termination it still retains a height of #gjj to #hjj feet4 ,limited on the west by the valley of the ,wainunu ,river and on the east by that of the ,yanawai ,river1 its breadth varies usually between four or five miles4 ,it is best seen in profile when viewed from the south-west on the western shores of ,wainunu ,bay1 between ,korolevu and ,nasawana1 when it presents itself to the eye as a table-land1 descending with a very gradual slope from the interior towards the coast4 ,from such a point of view the two great basaltic slopes of ,seatura and ,wainunu may be seen together1 the former descending eastward to the ,wainunu valley at an angle of #c or #d degrees1 the latter descending at right angles to it to the southward with a similar small gradient of #b or #c degrees4 ,in the profile of the island attached to this work the ,seatura slope is well shown2 but that of the ,wainunu table-land being seen from the south is represented only by a level contour-line at the base of the ,ndrandramea mountains4 ,the two great series of basaltic flows1 though closely approaching in a direction at right angles to each other1 do not come into actual contact1 and the intervening space is now occupied by the valley of the ,wainunu ,river4 ,in the accompanying rude outline-sketch of this region1 as seen from off the mouth of the ,wainunu estuary1 the relation of this valley to the two great series of basaltic flows is clearly shown4 ,on the left is the foot of the ,seatura basaltic slope2 on the right is the ,wainunu basaltic table-land2 and between them lie the estuary and valley of the ,wainunu1 at the back of which appears the 8,na ,savu0 table-land1 formed of basic tuffs and agglomerates4 ,behind all there rise up suddenly the ,ndrandramea mountains formed of acid andesites2 whilst in the foreground to the right is the hill of ,ulu-i-ndali1 which is composed in the mass of a grey basalt of a type quite different from the blackish basaltic rocks of the ,seatura slope and of the ,wainunu table-land4 ,it was from this view off the mouth of the estuary that ,i received my first lesson in studying the structural formation of the island4 ,i kept it always in my mind's eye1 and for months in an almost unmapped region it was my only guide4 ,illustration3 ,profile1 looking north from off the mouth of the ,wainunu ,river4 ,the gradual slope of the ,wainunu table-land from an elevation of #a1ajj or #a1bjj feet in the interior to #gjj or #hjj feet near the coast has already been referred to4 ,beyond this lower limit it descends much more rapidly and within less than a mile it terminates at ,masusu in a steep-sided declivity #cjj feet high opposite ,ulu-i-ndali1 and in a gentler slope on the eastern side in the ,ndranimako district4 ,its somewhat undulating surface is well wooded2 but on account of the small gradient the small streams on the table-land do not excavate deep channels1 but flow slowly along in shallow courses and often stagnate in swampy land where the interesting 8,scirpodendron costatum10 the giant-sedge1 flourishes4 ,in their beds occur reddish flinty concretions1 up to #c inches across in size1 and magnetic iron sand in great abundance4 ,a sample of this sand roughly washed on the spot contains #gg per cent4 of magnetic iron4#dd ,basaltic rocks1 often exhibiting a columnar structure1 are exposed at intervals on the surface and slopes of this table-land all over its area4 ,now and then when traversing this region one comes upon a tract strewn with large blocks1 amongst which occur fragments of huge columns #c to #d feet in diameter2 but it is on the steep southern slopes of the plateau in the vicinity of ,ndavutu and ,masusu that the most extensive exposures of columnar basalt are to be found4 ,here there have been large clearings made for the tea-plantations1 and portions of columns #b to #c feet in thickness are scattered all over the slopes and surface of ,masusu4 ,a very interesting exposure occurs on the southern edge of the ,masusu flat facing ,ulu-i-ndali4 ,here there is displayed in the face of a waterfall a mass of basalt about #dj feet deep1 formed of regular cross-jointed columns1 #c to #d feet in diameter and often pentagonal in shape1 which are almost perpendicular1 being inclined about five degrees from the vertical4 ,but in the upper portion of the fall the columns are smaller 7#b to #c feet across7 and become arched and nearly horizontal4 ,this was the only section of the inner mass of the basaltic flows that ,i found1 and here the columns are almost vertical4 ,in this locality several other exposures of the columnar basalt occur2 but they are all at the surface and the columns are nearly horizontal or very much inclined from the vertical1 being often pentagonal in form1 #b to #c feet across1 and sometimes curved with joints #aj to #bj feet in length4 ,neither vesicular nor scoriaceous rocks came under my notice in this region1 and the presence of pteropod-ooze deposits and of foraminiferous clays and tuffs on the slopes of the basaltic tableland indicates that the flows were submarine4 ,the common character of a sub-arial basaltic flow1 where there are large vertical columns below and smaller radiating columns above1 did not present itself2 and it is probable that the singular arrangement of the columns in the upper portion of these flows may be connected with the conditions of depth under which the flows took place4 ,it is apparent from the description given by ,dana of the columnar basalt of ,tahiti#de that it was formed under different conditions from those under which the basaltic flows of ,wainunu and ,seatura were formed4 ,the columns composing a cliff #ejj feet high in the ,matavai valley were #aj to #bj inches across4 ,a bluff1 #bjj to #cjj feet high1 in another part of the valley1 was made up of columns #e to #h inches in width4 ,the tallest cliff displayed in places converging and curved columns1 which is attributed to the unequal cooling of the interior of the mass2 but it is evident from a diagram given by the author that the columns were not inclined at a large angle from the perpendicular4#df ,he also refers to some prisms of a grey basalt exposed just below the ,wailuku ,falls near ,hilo in the large island of ,hawaii which were #h feet in diameter and were surmounted by others only #a to #d feet across4 ,the basalts of the ,wainunu table-land are blackish and non-vesicular1 with a density of #bhg to #bij4 ,they all carry olivine and microporphyritic plagioclase1 and display a little interstitial glass1 and the felspar-lathes are usually in plexus-arrangement1 being stout and often showing twin lamell4 ,but the rocks exhibit important variations in different localities as regards the amount of olivine1 the length of the felspar-lathes1 the presence or absence of the ophitic character1 c41 and they are grouped in different genera of the olivine class 7#a1 #ac1 #be1 #cc74 ,probably the type of genus #be1 with scanty olivine and granular augite1 would prevail4 ,from the varying size of the felspars of the groundmass it is apparent that the flows are not all of the same character4 ,at ,masusu1 where the rock is doleritic in texture1 they average from #be to #c mm4 in length4 ,a mile further north1 they are about #ag mm4 long1 and two miles more to the north they average only #a mm4 in length4 ,it is probable that a semi-vitreous basaltic andesite 7spec4 grav4 #bgc71 that shows no olivine and is referred to the porphyritic sub-genus of genus #i of the augite-andesites1 which is exposed in the stream-courses near the base of the dacitic mountains of the interior1 is the product of a later eruption4 ,occasionally one finds1 as at ,thongea in the ,wainunu valley1 a basalt rich in olivine 7spec4 grav4 #bie71 the felspars of the base averaging #a mm4 in length4 ,it may be remarked here that one cannot draw a sharp distinction between the basalts of this region and those of the adjacent eastern slope of ,seatura4 ,their specific gravity is about the same 7#bhg to #bij72 but the coarse texture of the ,masusu basalts did not come under my notice in the last locality1 where the felspars of the groundmass average #ah mm4 in length or about two-thirds the length of those of the ,masusu rocks4 ,by referring to the section across this part of the island1 it will be observed that the basaltic lavas of this table-land must have issued from some fissure near the south side of the base of the ,ndrandramea mountains4 ,in crossing the head of this plateau on the way from ,nambuna to ,ndrawa one passes from the region of the acid andesites into that of the basalts4 ,the track first skirts the base of ,mount ,wawa-,levu1 where the prevailing altered dacitic rocks are exposed in a much decomposed condition in the stream-courses4 ,then there is a gradual ascent through somewhat broken country to reach the western slope of the table-land1 and here are at first displayed the semi-vitreous basaltic andesites just referred to4 ,the ,wainunu table-land is bisected in a singular fashion by the ,ndavutu ,river4 ,since1 however1 the deep and often gorge-like channel of the river displays submarine deposits incrusting the basaltic slopes on its sides1 it is evident that the break in the basaltic table-land existed in part at least before the emergence4 ,with regard to the total thickness of the basaltic flows of this plateau ,i have only a few data4 ,in the bed of the ,ndavutu ,river opposite ,vunivuvundi1 and about #djj feet above the sea1 there is exposed a greyish porphyritic rock showing pyrites1 apparently an altered andesite4 ,if this is the bed-rock1 the basaltic plateau in that locality would be #cjj to #djj feet in thickness4 ,this is rather over the thickness of the end of the table-land at ,masusu4 ,i pass on now to consider briefly the submarine deposits that overlie the marginal slopes of this basaltic table-land in places4 ,they are for the most part pteropod and foraminiferous ooze-rocks and are extensively represented on the surface and slopes of the ,nandua flat to the north of ,ndavutu1 where they occur at all elevations up to #ejj feet above the sea4 ,they are also displayed on the eastern slopes overlooking the ,yanawai but at rather lower heights2 and little patches of them occur here and there in different places but not exceeding #ejj feet in elevation4 ,these friable clayey rocks1 which contain from #cj to #dj per cent4 of carbonate of lime1 are described in detail on page #cbj4 ,it may however be remarked here that these deposits are but partly derived from the degradation of the submerged basaltic table-land or from the washings of a basaltic coast4 ,they were formed in a clear sea-way1 but probably at no great depth1 at a time when the basaltic plateau was submerged below the level of breaker-action4 ,it is remarkable that these deposits do not repose directly on the basaltic rock4 ,in one place below the ,nandua tea-plantation1 where there is a steep descent to the river of about #bej feet1 the pteropod ooze-rock1 which is exposed in the upper half1 passes down into a chocolate-coloured marl that contains #e per cent4 of carbonate of lime and is horizontally bedded4 ,it is composed in the main of fine palagonitic debris1 with some fragments of minerals1 c41 and contains a few microscopic tests of foraminifera4 ,this deposit passes down into apparently a rock of pure palagonite4 ,the succession of these beds and their characters are described more in detail on page #cdd2 and as indicated in the diagram there given it is to be inferred that a very extensive formation of palagonite has taken place on the surface of a submarine basaltic flow4 ,on a similar slope of the ,nandua district1 and about half a mile nearer ,ndavutu1 the pteropod ooze-rock overlies a coarse zeolitic palagonite-tuff composed in great part of fragments of a highly altered vacuolar basic glass1 but without organic remains4 ,these tuffs are horizontally stratified4 ,tuffs precisely similar occur on the northern slopes of ,ulu-i-ndali three miles to the south4 ,they are all described in detail on page #cce4 ,some miles up the valley of the ,ndavutu ,river on the steep slope descending from ,vunivuvundi to the river1 and on the sides of the river lower down1 are exposed dark palagonitic and sometimes calcareous clays and tuffs4 ,i traced them as high as #dej feet above the sea where they were bedded and dipped gently to the west4 ,in the river-channel they were mostly confined to the right bank1 the slope on the other side being strewn with large fragments of columnar basalt4 ,at the mouth of the ,ndavutu ,river1 there are exposed tufaceous sandstones and a tuff-conglomerate1 probably in great part formed of palagonitic materials1 but ,i have kept no specimens4 ,there is much that is puzzling about the tuffs of the region between ,ndavutu and ,vunivuvundi4 ,the surface pteropod and foraminiferous ooze-rocks1 that are found here and on the ,yanawai or eastern border of the basaltic plateau and in other localities1 offer no difficulties2 but the origin of the palagonitic tuffs that in places lie beneath them is not so easy to explain4 ,at ,mr4 ,simpson's old estate on the ,nandua flat one finds numbers of huge blocks of columnar basalt scattered about on the slope descending to the river2 and in places there is exposed in a small stream1 up to a height of #ejj feet1 a fossiliferous ooze-rock containing marine shells4 ,the ooze-rock is evidently an incrusting deposit2 but when one goes down to the river-side1 which is there about #bjj feet above the sea1 one finds displayed in situ in the river-bed an amygdaloidal basic lava with coarse tuffs and agglomerates a little lower down4 ,,the ,,hill ,,of ,,ulu-,i-,,ndali4--,the meaning of the name of this hill is 8,head of the rope40 ,it is noted on account of the dense growth of tall forest trees that clothes its surface1 such as the ,vesi 7,afzelia bijuga71 the ,ndamanu 7,calophyllum burmanni71 the ,ndakua 7,dammara vitiensis71 the ,wathi-wathi 7,sterculia sp47 c42 and it may be that its name is connected with the launching of the large canoes that were at one time constructed on its slopes4 ,ulu-i-ndali1 which has a broad level summit #a1ajj to #a1aej feet in height1 rises on the left side of the mouth of the ,wainunu estuary4 ,its relation to the surrounding region is partly shown in the rough sketch given on page #hc4 ,it is separated from the basaltic table-land to the north by a deep and wide valley1 the bottom of which is raised only a few feet above the sea2 the small stream known as ,ndawa-ndingo1 that apparently flows through it1 is merely a branch of the ,wainunu estuary1 the tide ascending it for some distance4 ,this singular valley1 like the main valley of the ,wainunu1 dates back in great part to the period preceding the emergence of this region4 ,the steep basaltic slopes of ,masusu1 strewn with fragments of large columns1 bound it on the north4 ,on its south side are the lower slopes of ,ulu-i-ndali which are composed of volcanic tuffs4 ,a long spur descends to the south from ,ulu-i-ndali to form the rocky promontory of ,vatu ,vono or 8,stone turtle10 so-named from the fanciful resemblance of the large rounded blocks of basalt on the shore to the backs of turtles4 ,to the south-east extend the low tuff-formed ,ravi-ravi plains which are but slightly elevated above the sea4 ,the ,ulu-i-ndali range is apparently connected by a 8col0 with a range of similar height to the eastward1 the highest peak of which is about #c miles distant4 ,a more or less coarse doleritic grey olivine-basalt forms the mass of this hill and is chiefly exposed in its upper portion4 ,around its slopes1 extending from the coast usually halfway up the hill1 are blackish-brown olivine-basalts2 they differ amongst other points from the grey basalts--which are practically holocrystalline1 in their greater amount of interstitial glass1 to which1 doubtless1 is due their dark colour4 ,these dark basalts also occur scantily on the summit2 but from their greater prevalence on the lower slopes and from some other of their characters1 it may be inferred that they are in the main formed at the surface4 ,outside all1 on the north and south sides of the hill1 are exposed coarse tuffs composed of fragments of palagonitised vacuolar basic glass and containing much secondary zeolitic and calcitic materials4 ,they are purely of eruptive origin1 and although containing no organic remains were doubtless1 as in the case of the precisely similar tuffs of the neighbouring district of ,nandua1 deposited under the sea4 ,a description of their characters is given on page #cce4 ,such tuffs extend as high as #cjj feet above the sea on the north-west slopes1 where there are exposures1 #aj to #ab feet in thickness1 in the dry stream courses2 and here they may be seen overlying the basalt and rudely bedded1 dipping away from the summit at an angle of #ae degrees4 ,the grey olivine-basalts of ,ulu-i-ndali1 which often look like clinkstone1 range generally in specific gravity from #bi to #bie4 ,they contain microporphyritic olivine in abundance1 which is usually more or less hmatised and in extreme cases of the change looks like brown mica4 ,most of them are referred to genus #af of the olivine class and their characters will be found described on page #beh4 ,the felspar-lathes are stout and show sometimes lamellar twinning1 and on account of their large size 7#b to #e mm in average length7 the rock acquires a doleritic texture4 ,they display as a rule a flow arrangement around the olivine crystals4 ,augite granules occur in great abundance1 and there is rarely any interstitial glass4 ,these grey olivine-basalts are as a rule non-vesicular1 but rocks with minute irregular cavities1 though without glass1 occur scantily on the upper slopes4 ,they come near to the grey olivine-basalts of the hill of ,koro-i-rea in the ,solevu district1 as described on page #gg2 but they differ in their doleritic or coarser texture1 the felspar-lathes in the last-named locality being much smaller1 their average length being #ab mm4 ,the blackish basalts1 mostly characteristic of the lower slopes of ,ulu-i-ndali1 vary somewhat in character2 but they may on the whole be regarded as surface forms of the more deeply situated grey basalts which are practically holocrystalline4 ,the rock of this kind that prevails on the south and west sides has a specific gravity of #bif4 ,it is referred to the same genus 7#af7 as the grey basalts1 but differs from them in the circumstance that the microporphyritic olivine is serpentinised and not hmatised1 and in the occurrence of a fair amount of devitrified interstitial glass1 to which probably the dark colour of the rock is due4444 ,the dark aphanitic basalt1 with flinty fracture and a specific gravity of #cjj1 that is displayed in ,vatu ,vono ,point1 is merely a compact surface variety of the more coarse-textured grey basalts1 being referred to the same genus4 ,here there is a great abundance of microporphyritic olivine in a groundmass of parallel felspar-lathes and augite grains2 but the felspars are unusually small1 averaging #a mm4 in length2 and there is a much larger amount of fine magnetite than in the grey basalts4 ,there seems to be no interstitial glass2 and the olivine when not fresh is usually serpentinised but occasionally hmatised4 ,the dark basalts of ,ulu-i-ndali when they occur on its upper slopes become ophitic4 ,a specimen lying beside me has a specific gravity of #bia4 ,allowing for the structural differences1 it appears as an ophitic surface variety of the deeper seated grey basalts4 ,a description of it is given under genus #ab on page #bef1 of which it forms the type4 ,from the data above given1 the hill of ,ulu-i-ndali is to be regarded as the basal portion of a submarine volcano still retaining part of its ash-coverings4 ,the grey doleritic basalts probably represent the core and the dark fine-grained basalts represent the flows of this ancient vent4 ,,the ,,kumbulau ,,peninsula4--,south-east of ,ulu-i-ndali stretches a remarkable 8talasinga0 district which for convenience ,i will call the peninsula of ,kumbulau4 ,its south or seaward border is broken and hilly1 and presents an irregular line of hills #cjj to #dgj feet in height1 extending from ,kumbulau ,point to ,soni-soni ,island1 which is almost connected with the coast4 ,the rest of the peninsula is a low-lying and often marshy plain1 which1 though elevated in some places #bj to #be feet above the sea1 is usually much lower4 ,on the north-east side of the isthmus is the narrow ,nandi inlet1 bordered by low mangrove-belts1 which represents the broad channel that in a very recent period of the island's history cut through the present neck of the peninsula between the head of the ,nandi inlet and ,ravi-ravi4 ,stratified and often steeply inclined tuff-sandstones and clays1 more or less basic and palagonitic in character1 form together with basaltic agglomerates the prevailing rocks of the peninsula1 whether in the hilly portion or in the plains4 ,they belong to the basic tuffs of mixed composition described on page #ccj2 and though the agency of eruptions can be recognised in their components they are also the products of marine erosion4 ,some of the hills represent volcanic 8necks02 whilst the low narrow promontory between ,kiombo and ,soni-soni ,island has been formed by an old basaltic flow4 ,i will begin the description of this peninsula with the eastern extremity north of ,kumbulau ,point1 the interior of which is cut up into ridgy hills #cjj to #cej feet in height4 ,on its eastern coast are exposed volcanic agglomerates1 composed of large blocks1 which from their dimensions given below would weigh between one-third and two-thirds of a ton1 a size indicating the immediate vicinity of the vent1 now obliterated1 from which they were originally ejected4 ,near ,kumbulau ,point the blocks1 which are made of basaltic andesite1 measure five or six cubic feet4 ,further north in the vicinity of ,vatu-,ndamu1 the precipitous coast cliffs are composed of agglomerates1 the large blocks of which1 often ten cubic feet in dimension1 are formed1 not of the prevailing basaltic andesites1 as in other parts of the peninsula1 but of a grey hornblende-andesite4 ,this singular appearance of an acid andesite in a region of basic rocks has no doubt given rise to the native name of ,vatu-,ndamu1 8the red or brown stone40 ,it belongs to the second order of the hornblende-hypersthene-andesites1 and is described on page #bih4 ,proceeding along the south coast westward from ,kumbulau ,point1 before arriving at the village of ,na ,tokalau we pass from the district of agglomerates into that of the bedded tufaceous sandstones and clays which are exposed all along the coast to ,kiombo about three miles away4 ,the transition is indicated by the agglomerates becoming interstratified with the tuff-beds4 ,these sedimentary tuffs are as a rule steeply inclined at angles of #bj to #dj degrees1 the prevailing direction of the dip being to the north-east1 its uniformity for such a length of coast being noteworthy4 ,these beds however are occasionally 8crumpled02 and here and there a globular structure is developed4 ,the hills of this region of sedimentary tuffs between ,na ,tokalau and ,kiombo are the highest of the peninsula4 ,they usually attain a height of #djj feet1 but do not reach #ejj feet4 ,from each of them descends to the coast a spur terminating in a rocky point2 whilst between these points lie low sandy flats1 where the native villages of ,levuka1 ,kiombo1 c41 are situated4 ,the tuff-rocks extend to the top of the hills behind ,na ,tokalau1 and probably this will be found true of most of the other hills4 ,agglomerates are not common in the district4 ,in the point west of ,na ,tokalau1 however1 they are overlaid by basaltic agglomerates1 some of the blocks being scoriaceous4 ,in the point east of ,levuka1 a chocolate-coloured somewhat calcareous tuff-clay occurs interstratified in thin beds with the coarser deposits4 ,the general characters of these tuff-sandstones and tuff-clays have already been briefly referred to4 ,the former are much more prevalent and non-calcareous2 the latter are sometimes a little calcareous and look like marl1 and may perhaps contain a few tests of foraminifera4 ,both are formed of the debris of basic rocks and are more or less palagonitic4 ,the coarser deposits are described as sample ,a on page #ccj4 ,at times these tuffs are composed of much coarser fragments of the same materials1 some of them a centimetre in size4 ,a type of tuff intermediate in character is not uncommon4 ,the promontory that lies between ,kiombo and ,soni-soni ,island has been formed by a remarkable basaltic flow4 ,the low tongue1 about #ej feet high and #bjj to #cjj yards across1 in which it terminates1 was originally severed by a passage worn by the sea from the main portion2 but it is now joined by a low tract only #b or #c feet above the beach and partly occupied by mangroves4 ,the structure of the flow is well exhibited in the shore-flat and coast-cliffs west of ,kiombo1 and extending to the end of the point4 ,the waves have here cut into its mass and exposed its structure4 ,its lower part1 as exposed in the shore-flat1 is made of a compact hemicrystalline basalt2 whilst its upper portion1 as displayed in the cliffs1 #cj or #ce feet in height1 is composed of vitreous and semi-vitreous forms of the same rock looking like pitchstone4 ,the upper vitreous part is sometimes massive2 but usually it is rubbly1 with a tendency to form spheroidal masses4 ,all transitions can there be traced between the hemicrystalline rock of the shore-flat and the vitreous rock of the cliffs4 ,the rock of the shore-flat1 which has a specific gravity of #bhc1 is a blackish porphyritic basalt with scanty olivine1 and on account of the semi-ophitic character of the augites of the groundmass it is placed in genus #cc of the olivine class4 ,the plagioclase phenocrysts are #c to #e mm4 in size4 ,about half of the groundmass is made up of felspar-lathes 7#ag mm4 long7 and large augites 7#aa mm471 the rest consisting of a smoky devitrified glass containing a few irregular 8lacun0 filled with the residual magma in the form of a reddish-brown opaque palagonite-like material4 ,the rock intermediate between the lower and upper portions of the flow is also intermediate in character1 having a specific gravity of #bgg1 whilst quite three-fourths of the groundmass are of smoky glass4 ,the vitreous rocks of the cliffs1 though usually rubbly in appearance1 have also the aspect in places of brecciated pitchstone tuffs with the interstices filled with waxy palagonite2 but the microscopical examination shows that we have not to deal with a rock of detrital origin4 ,we have here the effects of the breaking up and crushing in situ of a dark-brown isotropic basic glass#dg carrying porphyritic plagioclase4 ,the interspaces then became partially filled with the finer fragments of the glass and of the crushed felspar2 but they were in the main occupied by a still liquid magma which penetrated into the cracks of the glass-fragments and into those of the felspars1 where the fractured portions in some cases remained in position4 ,there it has become devitrified and often palagonitised4 ,whether this liquid magma was produced by a partial remelting resulting from the heat developed during the crushing of the glassy upper portion of the flow during the contracting process1 or whether it was squeezed upwards from the less consolidated lower portion1 ,i cannot determine1 although the last supposition seems more probable4 ,at all events the edges of the glass-fragments are peculiarly eroded as if by the magma4 7,the bearing of these facts on the origin of palagonite is discussed in ,chapter ,,xxiv47 ,i infer that this flow has descended from the hills west of ,kiombo4 ,huge masses of agglomerate are exposed in the lower third of the hill marked 8#dgj feet0 in the chart1 and immediately north of the town4 ,fine clayey tuffs are exposed in the hill at the back and to the westward of this place2 but the locality requires a more detailed examination4 ,the absence to all appearance of vesicular and scoriaceous rocks in the case of this basaltic flow is remarkable4 ,this would not have been expected in the case of a supra-marine flow2 and indeed the testimony of the tuffs of this peninsula sufficiently indicates that during their deposition the whole district was submerged4 ,the future inquirer will doubtless discover some old volcanic 8necks0 in the hills of this peninsula4 ,one such hill overlooks the ,soni-soni inlet about a mile west of ,kiombo4 ,it is a singular isolated hill which ,i have named ,bare-poll ,peak for descriptive purposes4 ,in my notes its height is stated as #abj feet1 but it appeared to me to be rather higher than this4 ,it is capped by two huge masses1 #ad or #ae feet high1 of a dark grey slightly scoriaceous augite-andesite with a cryptocrystalline groundmass1 which apparently form the uppermost portion of a volcanic 8neck0 or pipe4 ,according to the size of these rock-masses the 8neck0 would have a circumference of #hj or #ij feet4 ,these masses are in part incrusted with agglomerate4 ,the adjacent island of ,soni-soni1 which is almost joined by the mangrove-belt to the adjoining coast1 probably represents one of the numerous small vents that were once active in this region4 ,its single peak is #dfj feet in height4 ,as there did not seem much prospect of finding rocks exposed on its upper part1 its slopes being densely covered with tall reeds1 my examination was confined to the lower portion during a walk around the island4 ,on its east and north sides occur rocks of much the same character as those exposed in the neighbouring low promontory to the east of it4 ,in addition to agglomerates and basaltic andesites occurred a rubbly pitchstone composed of fragments1 up to a centimetre in size1 of an opaque brown glass displaying a few phenocrysts of plagioclase and pyroxene1 the interstices being filled with crushed fragments of the phenocrysts and finer glass debris4 ,this rock is allied to the 8crush-tuffs0 described on page #ccd4 ,it may be added that the basic tuffs are more frequent on the west and south sides of the island4 ,the low island of ,na ,vatu in the midst of the ,soni-soni inlet is about #bej feet across and only #c or #d feet above the ordinary high-tide level4 ,in #ahih1 when ,i visited it1 this tiny island possessed about #bj houses and a population of #fj or #gj persons1 and ,i gather from ,hazlewood's account of these islands that ,na ,vatu was crowded with houses more than half a century ago4 ,it was apparently in the first place a sand-key1 and is protected against the wash of the waves by a low sea-wall formed of large blocks of stone4 ,an interesting exposure of bedded tuffs and clays is displayed at ,ravi-ravi on the west side of the peninsula4 ,a broad shore-flat has been formed by the marine erosion of a line of coast composed of these deposits4 ,the strike is well exhibited1 the dip being about #cj degrees ,n4 by ,w4 ,here there are alternating beds1 a few inches thick1 of coarse and fine tufaceous sandstones1 sometimes calcareous1 with marls or calcareous clays4 ,the mineral fragments of the coarser rocks are composed of plagioclase1 augite and rhombic pyroxene1 the last being abundant and giving a more acid character to these deposits4 ,the calcareous fragments appear to be principally shell debris4 ,the marl is in part composed of much finer detritus of the same minerals4 ,the other materials of these deposits are derived from the degradation of basic andesitic rocks1 and include also a little palagonite4 ,to the westward of ,ravi-ravi these beds show signs of disturbance1 being steeply tilted to the ,n4,w4 ,agglomerates also occur in the disturbed area4 ,the history of the ,kumbulau peninsula is evidently the history of the eruptive phases of a number of more or less submerged small vents and of the periods of great marine erosion that followed during the emergence of this part of the island4 ,the absence or rarity of dykes is remarkable2 but most of the hills would represent volcanic 8necks0 whether of massive rock1 tuff1 or agglomerate4 ,,the ,,district ,,between ,,the ,,kumbulau ,,peninsula ,,and ,,the ,,yanawai ,,river4--,between ,nandi ,inlet and the village of ,rewa the sea-border is low and often swampy1 whilst occasional spurs descend from the inland range into the swamps without reaching the coast4 ,pebbles of 8soapstone0 7foraminiferous mud-rock7 occur in streams and are no doubt derived from the incrusting deposits of the neighbouring hill slopes4 ,in one stream-bed in the swamps is exposed in situ a remarkable chocolate-coloured rock that looks like a greasy pitchstone or a palagonite-rock4 ,it is however of detrital origin1 and is composed in mass of minute fragments of a basic1 sometimes vacuolar1 glass in great part converted into palagonite2 whilst there are a number of broken crystals of olivine and plagioclase4 ,through the palagonitic alteration the fragmental character is somewhat obscured1 zeolites being extensively developed in the interstices4 ,a little lime occurs and there is a suspicion of foraminifera4 ,the deposit belongs to the group of palagonite marls described on page #cce4 ,the deeper rocks of the district are represented in a spur by an altered augite-andesite1 originally hemicrystalline and containing much granular epidote4 ,proceeding northward from the village of ,rewa1 one crosses another spur descending from the inland range4 ,it is formed in mass of a dark doleritic olivine-basalt 7spec4 grav4 #bia7 characterised by the length of the felspar-lathes 7#bh mm471 possessing a little interstitial glass1 and referred to genus #be of the olivine class4 ,it probably represents an ancient flow4 ,its surface is incrusted1 as high as the road ascends1 nearly #bjj feet above the sea1 by fine and coarse palagonite-tuffs2 whilst the pebbles of foraminiferous mud-rock in the stream indicate the existence of incrusting marine deposits further up the slopes4 ,the road then leads down into a low-lying undulating district that forms the sea border as far as the mouth of the ,yanawai1 and reaches about two miles inland without exceeding an elevation of #ajj feet1 although low hills occur here and there4 ,this region is fronted by mangrove swamps and is traversed by the ,matasawalevu and ,ndranimako streams4 ,it is a district of basic tuffs and foraminiferous clays1 which1 as shown below1 extend up the slopes of the basaltic ,wainunu table-land that lies behind4 ,the soil in all the low country between ,rewa and the ,yanawai is red1 heavy1 wet1 and clayey2 and affords a contrast to the dry friable soil of the ,kumbulau and ,kiombo region to the southward4 ,the ,navakavura plain lying north of ,rewa deserves especial mention4 ,it is a low1 swampy district which a mile inland is raised only #bj or #cj feet above the sea1 and is mostly occupied by casuarina and pandanus trees4 ,red argillaceous rocks1 representing more or less decomposed palagonite coarse and fine tuffs1 are exposed in the banks of the streams4 ,some of them were originally made up of fragments of basic glass which after being palagonitised became much disintegrated4 ,a typical specimen by my side has a soapy feel and looks like a lump of red clay4 ,microscopical examination shows that it is composed in mass of palagonite1 but in an extreme stage of the alteration process4 ,after traversing the ,navakavura plain1 one crosses a low hill rather over #ajj feet above the sea before descending to ,ndranimako4 ,on the hill are exposed reddish clay-rocks1 much weathered1 but showing vegetable remains and a few univalve and bivalve shells4 ,extensive submarine deposits occur in the inland district west of ,ndranimako4 ,they are the usual foraminiferous clay-rocks or 8soapstones10 and in places they contain pteropod shells4 ,they are well displayed in river-banks1 and in the hill-slopes on either side2 but they are probably of no great thickness since in one locality named ,na ,savu1 nearly two miles west of ,ndranimako1 the underlying basaltic rock is exposed in the bed of a gully1 the sides being of 8soapstone40 ,these deposits were formed in comparatively deep water4#dh ,the greatest elevation at which they were observed was about #ajj feet2 but this was as high as ,i reached in the ascent of the river4 ,according to the natives1 who are very observant in such matters1 these submarine deposits extend up the slopes of the adjacent ,wainunu plateau4 ,on page #hf reference is made to their occurrence on the slopes of this basaltic table-land1 #a or #b miles farther north4 ,in the district between the ,ndranimako and the ,yanawai rivers basic tuffs and 8soapstone0 prevail4 ,in this locality1 and especially in the vicinity of ,ndranimako1 siliceous concretions #b to #c inches across1 occur in places on the surface4 ,their nature is described in ,chapter ,,xxv4 ,from the foregoing remarks it may be inferred that the sea-border between the ,kumbulau ,peninsula and the ,yanawai ,river is formed of submarine deposits overlying basic rocks which probably represent ancient flows4 ,some of the deposits are largely formed of glassy erupted materials1 which have been converted into palagonite4 ,others again are more characteristic sedimentary formations accumulated in relatively deep water4 ,,chapter ,,vii ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,ndrandramea ,,district ,,this hilly region of acid andesites is a continuation of the mountainous backbone of the island1 being separated from the basaltic mountain of ,seatura by the saddle formed by the ,na ,savu table-land4 ,these acid andesites exhibit in nearly all cases a felsitic groundmass and phenocrysts of plagioclase and rhombic pyroxene2 whilst many of them are characterised by brown hornblende more or less pseudomorphosed in the manner described on page #cjf1 and a few display porphyritic quartz4 ,although these rocks have a common facies1 they vary considerably among themselves2 and it is difficult to find a term that would strictly include them all4 ,a general description of their characters is given in the chapter on the ,acid ,andesites4 ,in this interesting region a number of hills or mountains formed in mass of acid andesites rise up abruptly without any regular arrangement within an area measuring #e by #f miles1 and elevated #fjj to #a1jjj feet above the sea4 ,of these hills1 thirteen in all1 nine range in height between #a1fjj and #b1ejj feet above the sea1 none of the others rising less than #a1jjj feet above that level4 ,but the actual height of each hill above the country at its base is much less than this4 ,the height of the hill-mass1 in five or six of the largest1 ranges between #ijj and #a1bjj feet1 whilst in the smaller hills it varies between #djj and #hjj feet4 7,see accompanying plan47 ,illustration3 ,the ,,ndrandramea ,district from the westward4 ,the hills and mountains are of acid andesites and dacites4 ,the foreground is elevated about #dej feet above the sea4 ,face p4 #ih4 ,illustration3 ,rough plan of the ,ndrandramea district in ,vanua ,levu2 made with prismatic compass and aneroid by ,h4 ,b4 ,guppy4 ,these hills have sometimes a rounded profile1 when their summits are usually wooded4 ,others again terminate in conical bare rocky peaks1 either pointed or truncated4 ,they have often precipitous slopes and display vertical cliff-faces high up their sides4 ,their arrangement is rather singular4 ,to the south and apart from the others lies ,soloa ,levu 7#a1fjj feet74 ,navuningumu 7#a1icj feet7 is similarly isolated on the north4 ,on the east rises ,ngaingai 7#b1dcj feet71 the highest of the peaks1 with ,wawa ,levu 7#b1jjj feet71 ,vatu ,kerimasi 7#a1ijj feet71 ,vatu ,vanaya 7#a1fjj feet71 and ,mbona ,lailai 7#b1ajj feet7 closely clustered by its side4 ,on the west there is another group of hills1 of which ,ndrandramea 7#a1hjj feet7 is the highest and best known4 ,associated with it are ,kala-,kala 7#a1fjj feet71 ,mako-mako1 ,thoka-singa 7#a1cjj feet71 ,vatu ,mata 7#a1jej feet71 and another unnamed peak 7#a1djj feet7 lying west of ,ndrandramea4 ,the districts between and among the hills are much cut up into lesser hills and ridges1 the result of the very extensive denudation to which this region has been subjected4 ,the greater part of this area is drained by the ,tambu-lotu tributary of the ,wainunu2 but in the northern part we cross the watershed between the ,wainunu and ,ndreketi basins1 and to reach ,navuningumu we cross the valley of one of the tributaries of the ,ndreketi4 ,to the east of the ,ndrandramea region extends a broken country1 elevated rather more than #a1jjj feet above the sea1 and from it there rise one or two hills with bare cliff-faces1 which are probably composed of similar acid andesites4 ,although for the most part composed of these acid andesites1 each hill1 as far as my observations show1 has as a rule its own type of the rock1 differing from the others in specific weight1 in the texture of the groundmass1 and in the relative proportion of the porphyritic constituents4 ,the petrological characters will be found more fully discussed in ,chapter ,,xxi42 and only some of the more distinctive features will be noticed here in the following description of the district4 ,,the ,,ngaingai ,,group ,,of ,,hills4--,within a space less than a mile square rise ,ngaingai1 ,wawa ,levu1 and the other three hills above named1 so closely clustered together that the collective name of 8,hen and ,chickens0 might be aptly applied to the group4 ,the peculiar form of ,ngaingai is shown in the accompanying profile-sketch4 ,it is the ,nangorongoro of the ,admiralty chart4 ,the height of the mountain from its base is #a1ajj to #a1bjj feet4 ,its ascent1 which is not difficult1 may be made from the west side4 ,above its wooded slopes rises its bare rocky peak1 from which a magnificent panoramic view of the western half of ,vanua ,levu can be obtained4 ,characteristic dacites with porphyritic quartz came under my notice all the way up from the foot to the summit1 being occasionally exposed in perpendicular cliff-faces4 ,specimens taken from the upper and lower portions are uniform in character1 and have a specific gravity of #beg4 ,no other rocks were observed on its slopes4 ,the whole hill-mass is in great part if not entirely formed of these acid andesites4 ,the contrast between the narrow crested peak of ,ngaingai and the dome-shaped summit of ,wawa ,levu is seen in the sketch2 and this is the more remarkable because it is not associated1 as far as ,i could ascertain1 with any important difference in geological character4 ,wawa ,levu rises precipitously to a height of #ijj or #a1jjj feet above its base1 and displays often perpendicular cliff-faces on its sides4 ,its broad level soil-covered summit is mostly covered with young wood1 few of the trees having trunks more than #d inches in diameter1 whilst they are usually clothed with damp moss1 and are often decayed and rotten4#di ,true dacites1 closely similar to those of the neighbouring ,ngaingai and having a specific gravity of #bfa1 were displayed often in slab-like blocks from the base to near the top4 ,the rudely columnar structure to be observed in some of the other hills is rarely exhibited4 ,no other rocks came under my notice4 ,the remains of the stone walls of two old 8war-towns10 one of them named 8,ndaku-i-tonga10 occur on its south and south-east slopes4 ,illustration3 ,profiles of ,ngaingai and ,wawa ,levu from ,nambuna to the south-west4 ,both are dacitic mountains4 ,the other three hills of the ,ngaingai group were not ascended by me4 ,they show the same bare cliff-faces and have to all appearance the same geological character4 ,mbona ,lailai and ,vatu ,kerimasi are two blunt-topped conical hills with precipitous slopes that rise respectively about #ijj and #gjj feet above the country at their base4 ,vatu ,vanaya1 about #ejj feet in height1 has a rounded summit4 ,,the ,,ndrandramea ,,group ,,of ,,hills4--,a view of these hills from the westward is given in the accompanying illustration4 ,they have a lower elevation than the hills of the ,ngaingai group1 none of them rising to over #a1hjj feet above the sea1 whilst their height from the base is also less1 ranging between #djj and #ijj feet4 ,they rise1 as the illustration shows1 in the midst of a densely-wooded broken country4 ,ndrandramea1 which is #a1hjj feet above the sea1 has an individual height of about #ijj feet4 ,fijians in distant parts of the island are familiar with the name of this remarkable peak4 ,it has a legendary fame2 and like ,wawa ,levu in the old time it served as a mountain stronghold in times of war4 ,the remains of a stonewall of a 8koro-ni-valu0 or 8town of war10 known as ,mata-mei-ndami-ndami1 occur on its side1 #cjj or #cej feet below its summit2 whilst among the wild lemon trees that cover the slopes below large ovoid sling-stones #d or #e inches in length may still be found4 ,viewed from the south-east1 as shown in the frontispiece1 ,ndrandramea has the shape of a woman's breast2 and evidently the origin of its name is connected with this resemblance4 ,but seen from the west and south-west1 as in the other general view of the district 7page #ih71 it has a broadly truncated conical outline1 its form being indeed somewhat elongated or elliptical4 ,this hill presents precipitous slopes1 and on the south side it shows bare rocky faces4 ,as seen in the illustration1 it might appear inaccessible2 but the ascent is not difficult on the west side4 ,it is composed in mass of an acid andesite allied to the dacites of ,ngaingai and ,wawa ,levu1 but differing in the hemicrystalline character of the groundmass 7except at the base71 in the porphyritic development of rhombic pyroxene1 and in the absence of porphyritic quartz4 ,as remarked on page #cja1 the rock becomes more basic as one descends the hill4 ,at the top its specific weight is #bdd1 about #cjj feet below it is #beh1 at #gjj feet from the top it is #bfh1 and at the base of the hill where it is holocrystalline and has a dioritic appearance it is #bga4 ,that it possesses a rudely columnar structure is shown by the occurrence here and there on the slopes and at the base of the hill of portions of prostrate columns1 #c to #d feet broad and sometimes #bj to #be feet long1 which have a rounded surface and look like fossil tree-trunks4 ,masses of agglomerate of the same andesitic rocks lie about in places on the lower slopes1 the included blocks1 which are a few inches across1 being sometimes rounded4 ,the neighbouring hills lying south and west of ,ndrandramea are1 as far as my observations show1 of the same acid type of andesite4 ,it is connected with those nearest by a saddle1 #a1ajj feet above the sea1 where the same holocrystalline form of the rock occurs1 having a specific gravity of #bg and being often rudely columnar in structure4 ,kala-kala1 about #a1fjj feet above the sea1 is an imposing-looking hill with perpendicular cliff-faces on some of its sides4 ,i did not ascend it1 but found at its base a rock of the same andesitic type1 differing from that of ,ndrandramea in the more crystalline character of the groundmass1 and having a specific gravity of #bfa4 ,west of ,kala-kala is the outlying hill of ,vatu ,mata with a flat top and rising only about #djj feet from its base4 ,it has all the appearance of being composed of the same andesitic rocks4 ,it is shown on the left-hand in the illustration4 ,lying south of ,kala-kala are the two peaks of ,mako-mako and ,thoka-singa1 rising respectively #a1djj and #a1cjj feet above the sea4 ,i ascended the last-named1 which has a rounded summit covered with trees4 ,approaching it from ,nambuna on the east1 ,i found at its foot a large mass of pitchstone-agglomerate1 formed of fragments of vitreous basic rocks1 such as occurs around the lower part of ,soloa ,levu on the other side of the valley4 ,the slopes of ,thoka-singa1 between #bjj and #dej feet below the summit1 are strewn with masses of another kind of agglomerate made up of blocks #c to #h inches across1 occasionally rounded1 and composed of the same felsitic andesite1 of which the mass of the hill is formed4 ,this last-named rock is exposed in bulk in the upper part1 but on the summit the agglomerate reappears4 ,it has a granitoid appearance1 and is distinguished from the acid andesites of the other hills of the ,ndrandramea district by its greater specific gravity 7#bgb to #bgd71 by its holocrystalline texture1 and by the coarse grain of the mosaic of its felsitic groundmass1 which is probably quartz-bearing but is relatively scanty4 ,it is1 however1 referable to the same group of felsitic andesites1 but is to be placed at the basic end of the series4 7,its description is given on page #cjb47 ,in ,thoka-singa we have therefore a hill which is evidently formed in mass of these holocrystalline felsitic andesites but covered in places with an agglomerate of the same materials4 ,i have already referred to this feature in the structure of ,ndrandramea4 ,since the blocks are sometimes rounded1 such agglomerates may represent the result of marine erosion during the emergence of this part of the island4 ,in the case of ,navuningumu1 where they lie abruptly on calcareous clays containing tests of foraminifera and shells of pteropods1 a different explanation appears to be needed4 ,,the ,,hill ,,of ,,soloa ,,levu4--,this isolated hill1 which presents another type of these acid andesites1 has a broad rounded summit2 and though elevated about #a1fjj feet above the sea1 the hill itself rises only #hjj or #ijj feet above the country at its base4 ,it is not easy to obtain a view of the profile of this hill and to ascertain its relation to its surroundings2 and it was only when ,i viewed it from near the top of ,vatu ,kaisia six miles to the eastward that ,i was able to understand its position4 ,looking from that standpoint across the basaltic table-land of ,wainunu one observed ,soloa ,levu rising as a dome-shaped hill at the western margin of the table-land and apparently not separated from it4 ,the examination of the district shows that on the east and south-east sides this hill was in part surrounded by the great basaltic flows by which the table-land was built up4 ,basic tuffs and agglomerates1 however1 occur on the lower slopes on the north-west1 west1 and south-west sides1 so that ,soloa ,levu in fact lies in the midst of an area of basic rocks4 ,the type of acid andesite which is displayed in the upper two-thirds of the hill is distinguished from those of the other hills of the ,ndrandramea district by its orthophyric groundmass4 ,instead of a fine mosaic1 the matrix displays as a rule an arrangement of short stout plagioclase prisms2 but in one of my slides the two forms of groundmass are associated4 ,in their general characters as described on page #bif1 they cannot be separated from the acid andesites of the ,ndrandramea district4 ,their specific weight ranges between #bed and #bfb1 and like most of the other acid andesites they contain little1 if any1 interstitial glass4 ,huge blocks of these rocks lie about on the slopes1 often assuming a columnar form1 the fragments of such columns being sometimes #e or #f feet in diameter1 and #ab to #ae feet in length4 ,i found one such block standing erect like a solitary obelisk4 ,the best way to observe the basic rocks that invest the lower slopes of ,soloa ,levu is to follow the track that skirts it on the south side on the way from ,tambu-lotu to ,vunivuvundi4 ,palagonitic tuffs containing in places a little lime#ej and composed of fragments of basic glass of varying size and more or less palagonitised extend from ,tambu-lotu and ,nuku-ni-tambua 7two villages lying about a mile to the westward7 to the west and south-west slopes of ,soloa ,levu4 ,a pitchstone-agglomerate1 formed of fragments of a basic glass inclosing large crystals of plagioclase felspar one-third of an inch in length1 is associated with these tuffs on the lower north-west1 west1 and south-west slopes of the hill4 ,the tuffs are formed of the same materials as the pitchstone-agglomerates1 but differ in their character of being more or less palagonitised4 ,however1 on the north-west side the latter have also undergone this change4 ,on page #cab will be found a description of the basic glass of these agglomerates in its fresh and in its altered condition4 ,huge blocks of these rocks strew the surface on the south-west slopes of ,soloa ,levu1 and in one place the underlying acid andesite that forms the mass of the hill is exposed in a stream-course4 ,these pitchstone-agglomerates and palagonitic pitchstone-tuffs are elevated between #fjj and #gej feet above the sea4 ,as one proceeds on the road to ,vunivuvundi and skirts the south-east side of the hill one ascends the western border of the basaltic ,wainunu table-land which1 however1 is much cut up by rivers in this locality4 ,here the tuffs and agglomerates give place to a basaltic andesite1 and on reaching an elevation of #a1jjj feet we arrive at the top of the table-land from which an ascent of ,soloa ,levu is easily made4 ,the road then lies on1 but parallel to1 the border of this plateau for some distance until it descends into a deep valley worn by one of the tributaries of the ,wainunu ,river4 ,this hill of ,soloa ,levu is in fact a mass of acid andesite situated in the midst of an area of basic rocks4 ,i found basaltic rocks exposed in the stream courses to the north and similar rocks prevail on the north-west on the way between ,nambuna and ,tambu-lotu4 ,it has been above remarked that on the east and south it has been in part surrounded by the basaltic flows of the ,wainunu table-land1 and that pitchstone-tuffs and agglomerates cover its lower slopes on the west and south-west1 yet it is not easy to find any trace of the vent from which they flowed or were ejected4 ,it may be here remarked that the occurrence here and there of basic rocks in the midst of this region suggests the vicinity of dykes4 ,for instance1 in a deep gulley about half a mile south-west of ,kalakala1 where a dacitic rock was exposed in situ1 ,i came upon a single large mass of an aphanitic augite-andesite of the type described under genus #af1 species ,a1 of the augite-andesites4 ,,the ,,altered ,,acid ,,andesites ,,of ,,the ,,ndrandramea ,,district4--,one of the most important features of the geological structure of this district lies in the fact that the bed-rock exposed in the lower region between the hills is a highly altered acid andesite of the type found in the hills around4 ,by referring to the map of this locality1 it will be observed that between the ,ndrandramea hills on the west and the ,ngaingai hills on the east is the valley of the ,tambu-lotu river and its tributaries1 an open broken country deeply eroded by the streams1 and elevated #fjj to #gjj feet above the sea4 ,these altered rocks are well exposed in the deep gorge-like channel of the river between the village of ,nambuna and the foot of ,ndrandramea1 and in fact in all places in this district where the streams have worn deeply into the surface4 ,they have a coarse felsitic groundmass1 and are described under the felsitic order of the hypersthene-andesites on page #big4 ,they present all degrees of change from the hard dark grey mottled rocks1 in which the phenocrysts of plagioclase and rhombic pyroxene are in part replaced by calcitic1 viriditic1 and chloritic materials1 to those where the pseudomorphism and alteration is complete1 when the decomposition products give their character to a pale yellowish rock1 which sparkles with pyrites and often effervesces briskly with an acid4 ,after this comes the final stage of disintegration1 and we get a whitish rotten stone1 often full of pyrites1 the last condition of which is shown in a kaolin-like material exposed in the river-side4 ,the extensive alteration of these rocks is also indicated by the occurrence amongst the gravel of the river-bed and small stream courses near ,nambuna of fragments of clear quartz prisms1 half an inch across1 and of nodules1 three inches in size and sometimes hollow in the centre1 formed of radiating quartz crystals that once filled cavities in the altered rock4 ,small masses of vein-quartz also occur in these streams1 formed in a fissure by the growth of the crystals from the sides towards the centre4 ,i was unable to find the source of the quartz2 but it is probable that it was produced near the line of contact between the basaltic flows to the eastward and the older felsitic rocks of the district4 ,the great alteration of the acid andesitic rocks exposed as the bed-rocks in this region may in all probability be attributed to the vicinity of these basaltic rocks4 ,the two formations apparently come into contact about a mile east of ,nambuna4 ,in traversing this district on the road to ,ndrawa one first observes in situ in the streams the decomposed felsitic bed-rock with occasional loose blocks of a quartzitic rock that displays in the thin section a mosaic of irregular grains of quartz4 ,afterwards1 as one rises gradually to the top of the basaltic plateau1 basaltic rocks are alone exposed in position4 ,in the character of the fine river sand a clue may be found to the exact locality of the contact4 ,in the midst of the andesitic area between ,nambuna and ,ndrandramea1 the sand1 besides containing much magnetic iron1 is also composed to a large extent of rhombic pyroxene prisms1 clear quartz grains1 and fragments of plagioclase1 all derived from the porphyritic crystals of the dacites1 c4 ,near the basaltic district we find that the quartz and rhombic pyroxene have disappeared1 the sand being largely made up of magnetic-iron grains mixed with fragments of plagioclase4 ,illustration3 ,profile and ,geological ,section of ,vanua ,levu1 across the island from the ,sarawanga 7north7 coast to the ,yanawai 7south7 coast4 ,,the ,,extent ,,of ,,the ,,area ,,of ,,acid ,,andesite ,,rocks ,,in ,,the ,,ndrandramea ,,district4--,by referring to the map of this locality it will be observed that this region of andesites extends northward to the ,navuningumu ,range1 and that on the south it would be separated from the district of tuffs and agglomerates1 named the table-land of ,na ,savu1 by a line joining the hills of ,soloa ,levu and ,thokasinga4 ,on the east it is bounded by the basaltic area of the ,wainunu table-land4 ,on the west it extends at the surface1 with an occasional overlying patch of submarine tuffs and clays1 for a distance of at least two or three miles from the base of the hills1 and sometimes1 as in the direction of ,sarawanga1 more than half way to the coast4 ,i have endeavoured to show the relation of these acid rocks to the basalts and to the sedimentary deposits in the geological section4 ,when taking the track from ,sarawanga to ,nambuna by way of ,ndrandramea one soon enters the region of these acid andesites4 ,the prevailing rock exposed on the surface1 where it is usually much decomposed1 is a bluish-grey hypersthene-andesite with a specific gravity of #bed1 and displaying in a cryptocrystalline groundmass1 where the felsitic texture can be recognised1 abundant phenocrysts of plagioclase and rhombic pyroxene4 ,as high as #ejj feet above the sea it is occasionally capped by patches of palagonitised clays and tuffs scantily foraminiferous1 and at one place ,i noticed a patch of agglomerate1 the subangular blocks six to eight inches across being formed of the same acid andesite4 ,in the same way by taking the road from ,tembe-ni-ndio to ,nambuna1 passing the hill of ,kala-kala on the way1 we leave behind the foraminiferous tuffs and limestones of the lower coast regions2 and when about #djj feet above the sea we enter the inland district of felsitic andesites which begin about two miles from ,tembe-ni-ndio4 ,,the ,,navuningumu ,,range4--,by following the track from ,nambuna to ,navuningumu one skirts the bases of ,wawa ,levu and ,ngaingai1 where dacitic rocks are exposed4 ,after passing the watershed#ea between the ,wainunu and ,ndreketi rivers1 the track descends into the deep valley of one of the western tributaries of the ,ndreketi1 where a characteristic holocrystalline type of these felsitic andesites is exposed4 ,approaching ,navuningumu one finds exposed at its base agglomerates1 composed of scoriaceous and amygdaloidal semi-vitreous basic rocks1 overlying a dark tufaceous sandstone which on examination proves to be a basic pumiceous tuff of the type described on page #ccc1 and scantily foraminiferous4 ,we stand now in a region of basic rocks on the south-east side of the range1 and before us rises abruptly the weird-looking magnetic peak of ,navuningumu1 which is well represented in the accompanying illustration4 ,in the wet season its summit is usually enveloped in the thunder-clouds4 ,its elevation above the sea is #a1icj feet1 but estimated from its base its height is #a1jjj to #a1ajj feet4 ,the natives also name this peak ,na ,seyanga1 after a town that once existed in this locality4 ,it is the summit of a range that extends a mile or more to the north where it terminates in a lesser peak known as ,mumu4 ,ascending the peak of ,navuningumu from the south-east one finds exposed in its lower part1 up to #a1bjj feet above the sea1 pitchstone-agglomerates 7composed of fragments of a vitreous basic rock7 and white tufaceous sandstones 7containing a few tests of foraminifera71 such as are described below in the case of the neighbouring ,mbenutha ,cliffs4 ,between #a1cjj and #a1ejj feet there is displayed in position a typical dacite of the type described on page #cjc4 ,illustration3 ,,mt4 ,,tavia 7#b1baj feet7 from ,,vatu ,,kaisia4 ,it is probably formed of an acid andesite4 ,illustration3 ,the magnetic peak of ,,navuningumu 7#a1ica feet7 from the south4 ,the summit represents a basaltic neck4 ,face p4 #ajh4 ,the peak itself is formed of a dark-brown slightly vesicular semi-vitreous basaltic andesite1 of which1 in fact1 for the upper #bjj feet1 the summit is composed4 ,the rock is somewhat rubbly2 and where it is exposed on the bare peak it is powerfully magnetic1 displaying polarity in a marked degree1 and rendering the compass useless 7see page #cfh74 ,a specimen of the magnetic rock1 which is a little vesicular1 has a specific gravity of #bhb4 ,it is referred to genus #a of the augite-andesites described on page #bfg4 ,it displays in the slide porphyritic plagioclase1 with a little augite1 in a groundmass formed of a plexus of minute felspar-lathes 7#jf mm4 in length71 and exhibiting a large amount of a brown opaque glass in which grains and rods of magnetite with a few pyroxene granules are developed4 ,the magnetite in the groundmass1 although abundant1 is not in greater quantity than is usually found in semi-vitreous basaltic rocks without polarity4444 ,this terminal mass of basic lava-rock evidently forms the 8plug0 of a volcanic pipe that pierces the acid andesitic rocks of the district2 and from this ancient vent were doubtless ejected the basic tuffs and agglomerates that now cover the lower slopes of the mountain4 ,the conditions under which this volcano displayed its activity are further illustrated in a remarkable section exhibited on the east side of the mountain half a mile or more north of the summit4 ,here there is a line of bold cliffs1 in which1 as shown in the illustration1 a bed of agglomerate1 #fj or #gj feet thick1 overlies a series of foraminiferous clays and tufaceous sandstones1 which are elevated about #a1ajj feet above the sea4 ,the locality is named 8,mbenu-tha0 or 8,rubbish-heap40 ,it is well known to the natives on account of its caves1 which serve as a half-way resting-place on the road from ,nambuna to ,ndreketi4 ,these caves have been produced by the more rapid weathering of the underlying clays and sandstones4 ,the line of cliff extends northward to ,mumu1 the peak at that end of the range1 and preserves there the same structure4 ,the clays and tuff-sandstones are more or less stratified1 and dip generally to the west or south-west at an angle perhaps of #bj degrees2 but in more than one place they show signs of great disturbance1 being contorted and steeply tilted4 ,the foraminiferous clays form a more or less compact rock and contain #ae or #af per cent4 of lime4 ,they inclose pteropod shells in places and show many minute foraminiferous tests of the pelagic type4 ,their composition is given on page #cbc2 but it may be here remarked that the residue is made up mainly of palagonitic debris1 fine clayey material and minerals4 ,the mineral fragments form about #bj per cent4 of the mass1 and consist principally of glassy plagioclase1 with some rhombic pyroxene1 and magnetite1 their size averaging #a mm4 ,the tuff-sandstones interstratified with the clays contain only #b or #c per cent4 of lime1 and show only a few scattered microscopic tests of foraminifera4 ,about two-thirds of the rock consist of fragments of a bottle green basic glass1 vacuolar and but little altered1 the rest being composed chiefly of glass debris1 plagioclase1 and a little pyroxene1 the larger mineral and glass fragments averaging #c to #e mm4 in size4 ,they are in fact submarine hyalomelane tuffs very similar to those first met with at the foot of the mountain1 which are referred to on page #ajh4 7,they are described on page #ccc47 ,these interbedded clays and tufaceous sandstones of the ,mbenu-tha cliffs were deposited under somewhat different conditions4 ,the clays represent the quiet deposition in fairly deep water of fine materials derived from the degradation of acid andesites as well as of basic rocks4 ,the hyalomelane tuff-sandstones were formed more rapidly by the accumulation of fine volcanic ash consisting of fragments of a basic glass ejected from some neighbouring volcano that rose above the sea-surface4 ,submarine hyalomelane-tuffs with basic agglomerates appear to be of common occurrence around the base of the ,navuningumu mountain4 ,as we leave the range behind and begin to descend the long spur that slopes northward to ,ndreketi1 we find for the first mile or two these agglomerates4 ,but where the deeper rocks are exposed at an elevation of #fjj feet1 near the village of ,singa-singa1 there are displayed fine basic pumiceous tuffs and compact palagonitised clays containing little if any lime1 the last1 however1 containing a few casts of microscopic foraminifera4 ,the tuff is made up of minute fragments1 the largest less than #a mm4 in size1 of a basic hyalomelane glass1 which is vacuolar1 and often fibrillar like ordinary pumice1 and in places shows the early stage of alteration into palagonite4 ,the clay principally consists of more or less palagonitised debris of the same basic glass1 together with minute fragments of plagioclase and rhombic pyroxene4 ,these tuffs and clays represent the two conditions of deposition above referred to1 the last indicating a period of quiescence when the fine materials resulting from the degradation of both acid and basic andesites were slowly accumulating in deep water1 the first denoting the activity of a neighbouring supra-marine vent from which fine dust and ash formed of basic pumice were ejected4 ,illustration3 ,,mbenutha ,cliffs showing volcanic agglomerates overlying tuffs and clays1 containing shells of pteropods and foraminifera1 which are raised #a1ajj feet above the sea4 ,face p4 #aaa4 ,the bed of agglomerate1 #fj to #gj feet thick1 which overlies the foraminiferous tuffs and clays exposed in the line of cliff extending from ,mbenu-tha to ,mumu1 is made up of subangular blocks1 not usually over #f inches in diameter1 of an acid andesite of the general type found in the ,ndrandramea region1 but possessing a semi-vitreous groundmass4#eb ,by clambering up the steep slope on the south side of these cliffs1 it will be observed that this thick bed of agglomerate is covered by bedded foraminiferous clays and tuffs similar to those that underlie it4 ,it is therefore without doubt submarine1 and presents the result of the more violent outbursts of some neighbouring vent4 ,that this vent is now represented by the 8plug0 of basic lava forming the peak of ,navuningumu is highly probable4 ,it is1 however1 noteworthy that these beds of agglomerates1 tuffs1 and clays1 as shown in the photograph of the cliffs1 are all inclined at an angle of #bj towards the axis of eruption or to the westward4 ,the tuffs and clays underlying the agglomerates are1 as already remarked1 much disturbed in places4 ,it would seem that all the beds here exposed were originally horizontal1 and were tilted up during the disturbances accompanying the outbursts of volcanic activity4 ,the natural section1 which the ,mbenu-tha cliffs present1 is doubtless due to landslips4 ,similar exposures1 displayed by cliffs of basic agglomerate with submarine tuffs and clays at their base1 are common on the mountain-slopes of other parts of the island4 ,water oozes through the underlying soft deposits1 and the result is seen in the occurrence of huge masses of agglomerate on the slopes below4 ,from the details here given respecting ,navuningumu and its surroundings1 it is apparent that there have been two stages in the history of this volcanic mountain4 ,the first was submarine and was characterised by the discharge of acid lavas which consolidated around the vent and were afterwards covered over with deposits of foraminiferous clays4 ,the second was in the last part supra-marine4 ,with the renewal of activity1 the overlying acid andesites were broken through and basic materials were discharged from the new vent4 ,the bed of acid agglomerates exposed in the ,mbenu-tha cliff belongs to that period of the second stage when the explosive agencies were most violent4 ,it represents the extensive destruction of the overlying rocks4 ,the foraminiferous tuff-sandstones are submarine accumulations of the finely comminuted fragments of basic pumice that constituted the dust and fine ash discharged from a supra-marine vent4 ,the scoriaceous and amygdaloidal blocks of the basic agglomerates overlying these tuffs around the base of the mountain have had a similar origin4 ,the original ash-cone that at one time rose above the surface of the sea has long since been destroyed by the denuding agencies2 and its situation is alone indicated by the 8neck0 of basic lava-rock that forms the peak of ,navuningumu4 ,a very long period must have elapsed since this last stage in the activity of the vent4 ,the clays containing pteropod-shells and tests of foraminifera1 with which the basic pumice tuffs and the acid agglomerates were interstratified1 are now about #a1ajj feet above the sea1 and are situated in the centre of the island4 ,during the emergence the denudation of the new land-surface was no doubt very great2 and these submarine clays and tuffs1 as displayed in the cliffs1 owe their preservation in great part to the protection of the overlying mass of agglomerate4 ,much light is thrown on the history of the whole ,ndrandramea region of acid andesites by the examination of this old volcano of ,navuningumu4 ,some of the hills1 as in the case of ,ngaingai and ,wawa ,levu1 seem to have been stripped of everything that could give information to the geologist4 ,others again1 like those of ,thoka-singa and ,ndrandramea1 display here and there on their slopes agglomerates of the same materials1 the rounded forms of some of the blocks being in part indicative of marine erosion during the emergence of this region from the sea4 ,in ,soloa ,levu1 however1 we have one of these hills partially surrounded by later basaltic flows and covered in places on its lower slopes by basic tuffs and agglomerates1 probably submarine4 ,in ,navuningumu the original mass of acid andesite is only scantily exposed4 ,it is for the most part buried beneath submarine clays which are in their turn covered by the tuffs and agglomerates of later basic eruptions4 ,,chapter ,,viii ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,mount ,,vatu ,,kaisia ,,and ,,district ,,this peak1 #a1hhj feet in height1 starts up suddenly in the mountainous interior of the island4 ,being situated in the valley of the ,yanawai river1 which opens to the south1 it forms a conspicuous landmark for vessels off the south coast2 but from most other points of view1 on account of its peculiar situation1 it is usually difficult and often impossible to obtain even a glimpse of it4#ec ,from its remarkable blunt-topped conical shape it has received the not very appropriate name of ,marling ,spike in the ,admiralty charts4 ,the natives name it ,vatu ,kaisia1 the first word signifying 8rock10 whilst the second is the name of a demon4 ,illustration3 ,profile-sketch of the ,vatu ,kaisia district from ,s4,s4,e4 ,some idea may be formed of its situation and of the character of the neighbouring country from the profile-sketch and photograph here produced4 ,i was unable for reasons given below to take a photograph of the mountain itself1 as it was either too near or too far away4 ,vatu ,kaisia is approached either from ,ndrawa on the north or from ,ndawara on the south1 the ascent being best made from the west side4 ,the regions traversed on the way are so densely wooded that the mountain does not become visible until the traveller is right upon it4 ,he becomes suddenly aware that there is some huge mass close to him looming above his head through the trees2 and it is with a feeling of awe that he first looks upon a mountain that although only a few hundred yards away nearly escaped his search4 ,he is startled by its proximity1 and wonders what strange forces have been at work to place it there2 but his view is transitory1 and whether proceeding north or south he sees it no more1 unless he essays to climb its slopes4 ,vatu ,kaisia lies not in the centre but towards the west side of the ,yanawai valley the river flowing as an impetuous stream around the foot of its eastern slope4 ,in the profile-sketch the mountain itself conceals the peculiar feature of its position1 which is1 however1 shown in an exaggerated form in the geological section below4 ,on its west side rises a broad ridge running south which in places is not much higher than the basaltic plateau of ,wainunu to the west of it4 ,this ridge is only separated from ,vatu ,kaisia by a dark narrow gorge not many hundred yards in width1 across which my natives were able to make themselves heard when near the summit4 ,the mountain rises #a1ajj or #a1bjj feet above the gorge on its west side1 which is #gjj feet above the sea1 and some #a1djj or #a1ejj feet above the ,yanawai river on the east1 which is #cjj or #djj feet above the sea4 ,it possesses two peaks1 of which the western one is smaller and lateral and has a height of #a1fjj or #a1fej feet1 whilst the eastern is the main peak and rises to #a1hhj feet4 ,the saddle between the peaks has an elevation of about #a1ejj feet4 ,it is very difficult to obtain a distant view of the two peaks1 which lie about ,n4,w4 and ,s4,e4 with each other4 ,they are either merged into one as in the view from the south1 or else the highest portion of the main peak is alone visible4 ,on the lower slopes of the mountain as high as #a1ajj or #a1bjj feet is exposed a porphyritic doleritic basalt showing semi-ophitic augite and abundant interstitial glass4 ,its specific gravity is #bh1 but there is no olivine4 ,it belongs to a type of basalt described under genus #i1 sub-genus ,a1 of the augite-andesites4 ,the upper double-peaked portion rises precipitously1 displaying bare rocky cliff-faces with a drop of #ajj or #aej feet1 and formed in mass of a grey andesitic rock with a specific gravity of #bga and showing abundant small porphyritic crystals of hornblende and rhombic pyroxene4 ,it represents a type of the hornblende-hypersthene-andesites described on page #cja4 ,i was unable1 through want of a rope-ladder1 to accomplish the last hundred feet of the summit2 but the general uniformity of structure was evident4 ,no detrital rocks came under my observation4 ,that the porphyritic basalt represents a later flow around this old andesitic mountain is indicated amongst other things by this absence of tuffs and agglomerates4 ,vatu ,kaisia is undoubtedly the core of an ancient cone of hornblende-andesite1 and as in the case of ,mount ,soloa ,levu1 which is formed of somewhat similar andesites 7see page #ajc71 it has been more or less completely surrounded by later basaltic flows4 ,vatu ,kaisia and ,soloa ,levu occupy similar positions with respect to the great basaltic table-land of ,wainunu1 the first lying just within its eastern border1 the second lying partly within its western margin4 ,the structure of the ridge immediately west of ,vatu ,kaisia lends support to this view of the formation of this region4 ,the ridge is here1 it is true1 elevated a hundred feet or so above the table-land which is about #a1jjj feet above the sea2 but whilst on its slopes facing the mountain the same porphyritic basalt prevails1 there is a limited exposure on its top of the same rock 7sp4 gr4 #bfh71 differing only in the larger size of its porphyritic crystals of hornblende and rhombic pyroxene4 ,illustration3 ,vatu ,kaisia ,the narrow gorge isolating the mountain on the west is occupied by a tributary of the ,yanawai ,river4 ,it has a depth of #djj feet below the ridge2 and as illustrated in the section below it has evidently been largely formed by the eroding agency of the stream4 ,however1 at the bottom of the gorge there is exposed a heavy aphanitic basalt showing no olivine and having a specific gravity of #bhe4 ,though of much finer texture1 the felspar microliths only measuring #je mm4 in length1 it differs conspicuously from the overlying porphyritic basalt in possessing little or no interstitial glass4 ,it is referred to genus #af1 species ,a1 sub-species #a1 of the augite-andesites 7page #bhj74 ,the probable structure of this district is shown in the geological section here given4 ,it is assumed from the limited exposure of the same rock on the top of the ridge that the basaltic flows which surrounded the lower portion of ,vatu ,kaisia at the same time covered over another similar peak lying immediately west of it4 ,through stream-erosion ,vatu ,kaisia has now been isolated on its west side2 and since the basaltic rocks rise to about the same height on both sides of the gorge thus produced1 the original surface was probably as indicated by the dotted line in the diagram4 ,by following the summit of the ridge1 as it runs south on the right side of the ,yanawai valley towards ,ndawara1 some interesting rocks are observed4 ,for the first mile from the camping-place opposite ,vatu ,kaisia the elevation increased from #a1ajj to #a1cjj feet1 and blocks of a blackish basaltic andesite 7sp4 gr4 #bgf7 lay on the ground4 ,about a mile further on fragments of white quartz-rock appeared on the surface having been thrown out of a shaft close to the track which had been sunk to a depth of #ae or #bj feet by a gold miner#ed a few years before4 ,i could not descend the shaft to examine it3 but the specimens picked up are evidently a white vein-quartz1 some of them having a striated 8slickenside0 surface on one side4#ee ,there is evidently a 8contact0 in this locality1 probably of a basaltic rock with an acid andesite4 ,leaving the shaft1 the track proceeds southward and eastward1 and one descends gradually from a height of #a1ajj feet down to the ,yanawai river where the elevation is only about #aej feet above the sea4 ,occasional blocks of basaltic rocks lie on the surface of the ridge1 and in one locality there is exposed a curious-looking agglomerate formed of fragments of a greenish altered augite-andesite1 somewhat scoriaceous1 the cavities being filled with a zeolite4 ,at the crossing of the river a black basalt 7sp4 gr4 #bhb7 occurs in situ2 whilst loose blocks of basalt and of an acid andesite occur in the river-bed4 ,continuing the journey from the ,yanawai crossing to ,ndawara near the mouth of the river1 one follows the track across a range of hills1 #ejj to #fjj feet in height1 basaltic rocks prevailing on the surface4 ,,the ,,nandronandranu ,,district4 ,lying north-west of ,vatu ,kaisia is an elevated district which ,i have named after its highest summit1 a square-topped peak rather higher than ,vatu ,kaisia and probably about #b1ajj feet above the sea4 ,koro-ni-yalewa1 which signifies 8town of the women10 is another name of this peak4 ,it is shown in the sketch given on page #aac1 and is situated about two miles north-west of ,vatu ,kaisia4 ,i did not ascend this mountain1 which from its form would seem to be made of an acid andesite like the ,ndrandramea peaks4 ,much of this elevated region varies between #a1jjj and #a1ejj feet in elevation4 ,it is connected with the ,ndrandramea district by somewhat broken country not much over #a1jjj feet in height1 which is the 8divide0 between the river systems of the ,ndreketi and ,wainunu4 ,a long tongue-like extension of similar elevation projects to the north-west between the ,ndrawa and ,navuningumu branches of the ,ndreketi4 ,this elevated region is continuous to the eastward with the ,tavia ,range which is described below4 ,for convenience the valleys of the upper course of the ,ndrawa river have been included in this district as their geological features can in this connection be best explained4 ,this region is well distinguished from most of the other districts of the island by the prevalence of aphanitic augite-andesites4 ,these rocks have also supplied the agglomerates of the locality1 and the palagonite-tuffs which are in places extensively represented are evidently in great part derived from vitreous forms of the same rocks4 ,we seem to get nearer to supra-marine eruptions in this region than in most others4 ,the palagonitic-tuffs and agglomerates appear to have rapidly accumulated in shallow water1 and there is reason for regarding one exposure of the aphanitic augite-andesites as at all events a shallow-water lava-flow4 ,the aphanitic character of the massive rocks1 however it may have arisen1 is here1 as ,i take it1 associated with the shallow-water habit of the tuffs and agglomerates4 7#a7 ,,east ,,side ,,of ,,the ,,nandronandranu ,,district4--,by following the track leading from the ridge on the west side of ,vatu ,kaisia northward to ,ndrawa one rises gradually to a more elevated region4 ,the rocks exposed on the surface for the first mile are for the most part altered hypersthene-augite-andesites possessing a micro-felsitic groundmass4 ,when a height of about #a1djj feet was attained1 the track could not have been far from the peak of ,nandronandranu1 but on account of the wood no view was obtainable4 ,in this locality between #a1cjj and #a1djj feet soapy palagonitic clay-rocks and coarser palagonite-tuffs are displayed on the surface4 ,no organic remains are to be noticed in the specimens collected here1 but they are much affected by hydration4 ,judging from the fossiliferous character of similar deposits over a large part of the island1 it is highly probable that these tuffs and clays are also submarine4 ,afterwards a descent was made to an undulating region about #a miles across and elevated between #gej and #hej feet4 ,the blocks there displayed on the surface are composed of a dark rather compact augite-andesite with a specific gravity of #bge 7see genus #ac7 and of an altered greenish aphanitic augite-andesite with a specific gravity of #bei in which calcite occurs as an alteration product 7genus #af74 ,aphanitic rocks of this character as shown below1 are very prevalent in the north-west and north parts of the ,nandronandranu district1 but are not usually altered4 7#b7 ,,the ,,north-,,west ,,part ,,of ,,the ,,nandronandranu ,,district4--,the best route to follow here is to take the track from ,nambuna to ,ndrawa4 ,after crossing the upper portion of the ,wainunu table-land one reaches the headwaters of the ,ndavutu ,river and then ascends the watershed between the ,ndreketi and ,wainunu river-systems1 reaching ,savulu1 about #a1jej feet above the sea1 where a solitary house marks the site of an old mountain town4 ,this region is much cut up in deep valleys usually #bjj to #cjj feet deep1 which are occupied by affluents of the ,ndrawa branch of the ,ndreketi1 flowing north4 ,the valley of the main affluents is from #djj to #ejj feet in depth2 and this constant ascent and descent of steep and often slippery valley sides makes the journey very tedious4 ,at ,savulu one stands within the ,nandronandranu district4 ,behind lies the ,wainunu table-land with its olivine basalts2 but here aphanitic augite-andesites prevail and extend to ,ndrawa and beyond4 ,they are exposed in position in the stream-courses and furnish most of the blocks and pebbles found in the bed of the main ,ndrawa ,river for miles down its course towards the sea4 ,they are dark1 compact1 and non-porphyritic rocks and are all referred to genus #af of the augite-andesites as described on page #bgi4 ,they vary1 however1 in certain features1 as in the specific gravity1 the amount of glass1 c4 ,the residual glass is1 however1 usually small2 but in a stream-course east of ,savulu ,i found in position at an elevation of #gej feet a semi-vitreous scoriaceous variety of these rocks1 in which the steam-pores had been drawn out into long tubular cavities half an inch and more in length4 ,the scoriaceous character is infrequent2 but reference should here be made to another exposure of a slaggy semi-vitreous rock showing abundant steam-pores in the tuff-district of the river valley above ,ravuka4 ,it differs in some respects from the prevailing rock1 since it displays prismatic augite as well as felspar microliths in its glassy groundmass1 and is for this reason referred to genus #bj of the augite-andesites4 ,in the elevated region east of ,savulu the aphanitic augite-andesites are in places overlain by tuffs and agglomerates formed of the same materials4 ,there is a very good exposure of the tuffs in the ,nganga-turuturu cliffs about #b miles west of ,savulu4 7#c7 ,,the ,,nganga-,,turuturu ,,cliffs4--,these picturesque cliffs1 #ej to #gj feet in height1 rise up at the head of the ,liwa-liwa valley between ,savulu and ,ndrawa4 ,they are elevated about #a1bjj feet above the sea2 and probably derive their name from a small waterfall which1 after descending over their face1 drops into the valley below4 ,at its bottom is situated the hamlet of ,liwa-liwa1 which is about #fjj feet above the sea4 ,this is the ,fijian word for 8cold10 and doubtless it has allusion to the coolness of the valley4 ,on account of the more rapid weathering of the tuffs in the lower part of the cliffs1 there is a rude shelter afforded by the overhanging portion which is the main feature of interest that the cliffs present from a native's point of view4 ,the tuffs composing the cliffs are horizontally bedded and overlie the prevailing aphanitic augite-andesite exposed on the valley-slopes below4 ,originally grey in colour1 they have been largely affected by the hydration accompanying the weathering process4 ,they are fine in texture and somewhat friable1 but contain no lime1 and are chiefly made up of the palagonitised fine detritus of vitreous varieties of the aphanitic augite-andesites of the district4 ,no organic remains came under my notice4 ,some of the beds contain a number of lapilli of basic pumice1 #a to #c centimetres in size1 which are often in the last stage of the disintegration produced during palagonitisation4 ,it would seem probable that these lapilli1 after having been ejected from some supra-marine vent1 were deposited with the tuffs in the sea around4 ,it should1 however1 be not forgotten that vesicular and pumiceous materials may be discharged during a submarine eruption4 ,when ,i visited the museum at ,catania1 ,prof4 ,platania showed me portions of a bomb1 highly vesicular1 that had been thrown up in a submarine eruption off ,vulcano in the ,lipari ,islands4 7#d7 ,,the ,,upper ,,valleys ,,of ,,the ,,ndrawa ,,river4--,the two valleys of ,liwa-liwa and ,ndrawa meet at ,ravuka1 where their two streams unite to form the main ,ndrawa ,river4 ,the former is the largest2 and its large impetuous stream1 during its descent of about two miles from ,liwa-liwa past ,lutu-kina to ,ravuka1 which is between #bjj and #bej feet above the sea1 has a drop of #cjj or #cej feet4 ,the main stream flows with a gentle gradient to the coast about ten miles away4 ,i did not descend its course for more than two miles below ,ravuka1 where some hot springs well up through the gravel on the left bank 7see page #ca47 ,this is a region of palagonite-tuffs which like those of the ,nganga-turuturu cliffs are mainly derived from vitreous and semi-vitreous aphanitic augite-andesites4 ,they do not effervesce with an acid1 and neither foraminiferous tests nor other organic remains occur4 ,the palagonitic material is usually vacuolar1 the vacuoles being filled with palagonitic glass or with a zeolite as in the more altered rocks4 ,where bedding is shown1 the beds are generally horizontal4 ,these tuffs are extensively displayed in the sides and beds of the rivers from ,liwa-liwa and ,ndrawa to ,ravuka and as far as ,i went down the main river1 namely to the hot springs4 ,they are associated with agglomerates1 formed of the aphanitic augite-andesites1 below ,ravuka and in the ,ndrawa valley4 7#e7 ,,the ,,vicinity ,,of ,,ndrawa4--,the village of ,ndrawa1 which is not elevated more than #cjj feet above the sea1 is situated in the heart of the island in a deep valley more or less hemmed in by the mountains4 ,this is one of the wettest localities in ,vanua ,levu1 and probably1 as in the case of that of ,ndriti in the ,seatura basin1 the rainfall is not far under #cjj inches in the year4 ,in the river-gorge descending westward to ,ravuka are displayed horizontally bedded palagonite-tuffs and agglomerates above referred to in the description of the ,ravuka district1 and the same rocks are exposed on the mountain-slopes to the south of the village4#ef ,immediately to the north lies a broken hilly country1 about #hjj feet above the sea1 which has to be crossed on the way to ,mbatiri and is much cut up by streams descending from the vicinity of ,na ,raro to join the ,ndrawa ,river below ,ravuka4 ,the prevailing rocks are tuff-breccias and agglomerates4 ,the first are made up chiefly of angular fragments1 less than an inch in size1 of aphanitic augite-andesites1 some of them being more or less vitreous and in different stages of palagonitisation1 whilst the finer material derived from the same rocks contains some carbonate of lime4 ,the agglomerates are composed of the same type of these augite-andesites1 with however but little interstitial glass4 ,it should be added that pebbles of a kind of jasper or iron-flint occur in the stream-beds in this locality4 7,the microscopical characters are described on page #cee47 ,by following up the valley that extends to the east from ,ndrawa1 one enters after about a mile into the region of ,na ,raro1 which is described on page #abc4 ,,the ,,tavia ,,ranges4 ,north of ,vatu ,kaisia the elevated ,nandronadranu district divides into two ranges1 one of which stretches eastward to the south of ,na ,raro as far as the gap of that name1 whilst the other extends southward on the east side of the ,yanawai valley4 ,near the angle of bifurcation is situated ,mount ,tavia1 a remarkable pyramidal peak marked #b1baj feet in the ,admiralty chart and lying #a miles north-east 7,n#cc;,e7 of ,vatu ,kaisia4 ,it is shown in the view facing page #ajh4 ,all this region is densely wooded1 and ,i had chiefly to rely on 8course-and-distance10 and on my aneroid1 to determine the surface-configuration4 7#a7 ,,range ,,on ,,the ,,east ,,side ,,of ,,the ,,yanawai ,,valley4--,no ascent of these hills was made4 ,they vary from #a1ejj to #a1hjj feet in height1 and judging from the loose blocks and gravel in the bed of the ,yanawai ,river below ,vatu ,kaisia they would seem to be mainly formed of basaltic rocks1 acid andesites being also represented4 ,however1 ,i crossed the southern end of the range1 where it is #ejj to #fjj feet in height1 to the north of ,ndawara1 and found basaltic andesites prevailing at the surface4 7#b7 ,,range ,,extending ,,eastward ,,from ,,mount ,,tavia ,,on ,,the ,,south ,,side ,,of ,,na ,,raro4--,mount ,tavia1 which has the appearance of a dacitic peak1 was not ascended2 but the range was crossed in two places in going from ,ndrawa to ,vatu-vono and from ,valeni to ,nareilangi1 its usual height varying between #a1bjj and #a1ejj feet1 the extreme height being about #a1gjj feet4 ,in making the traverse from ,ndrawa to ,vatu-vono1 one first passes through a part of the hornblende-andesite region of ,na ,raro1 which is described in a later page4 ,afterwards while ascending the north slopes of the range1 basaltic andesites1 often doleritic in texture and referred to genus #a of the augite-andesites1 are usually found as far as the summit #a1bjj to #a1cjj feet above the sea4 ,on descending the south slopes one finds coarse and fine palagonite-tuffs and clays at #ijj to #a1ajj feet up1 similar to those prevailing near the sea-border4 ,they are probably submarine1 but my specimens are weathered and give no effervescence with an acid4 ,in the bed of the river above ,vatu-vono1 about #djj feet above the sea1 there occurs in position an aphanitic augite-andesite 7spec4 grav4 #bgg71 referred to genus #af1 species ,a2 whilst blocks of a coarser grained basaltic andesite lie loose in the stream4 ,in my traverse across the range from ,valeni to ,nareilangi ,i noticed about a mile from ,valeni and not much over #ajj feet above the sea an agglomerate formed of blocks of an altered acid andesite possessing a micro-felsitic groundmass and showing microporphyritic rhombic pyroxene with dark alteration borders 7spec4 grav4 #be74 ,it is distinct from the ,na ,raro rocks2 and its presence in an agglomerate seems to indicate the vicinity of some old acid andesite peak buried beneath later basic eruptive products4 ,ascending the south slopes of the range1 ,i found decomposing basaltic andesites and basic tuffs1 the prevailing rocks up to an elevation of #a1cjj feet2 but in one locality 7#hjj feet7 occurred large masses of what seemed to be a disintegrating dacitic rock penetrated by quartz veins less than an inch thick4 ,an aphanitic augite-andesite1 of a somewhat exceptional character 7spec4 grav4 #bfc71 was displayed at the top of the ridge1 #a1ejj feet above the sea4#eg ,basic rocks were exposed in the spur running northward on the east side of ,na ,raro4 ,,the ,,sea-,,border ,,extending ,,east ,,from ,,the ,,yanawai ,,river ,,to ,,the ,,lango-,,lango ,,river4--,in this district is included the area between the foot of the slopes of the ,tavia ,ranges and the shores of ,savu-savu ,bay4 ,this undulating country1 two to three miles in breadth1 does not attain a greater elevation inland than #cjj or #djj feet4 ,fine and coarse palagonite-tuffs1 some of them with the texture of sandstone1 are the characteristic rocks4 ,they at times contain a little lime and probably a few tests of foraminifera4 ,the palagonitised glass is often vacuolar1 the vacuoles being filled with the same material4 ,in places where they are well displayed these tuffs generally show bedding1 as in a hill-slope just east of ,vuni-evu-evu1 where there are fine and coarse tuffs interstratified and dipping gently ,w4 by ,s4 ,basic agglomerates also occur in this district4 ,in the promontory named ,yanutha ,point in the map there is displayed an old flow of basaltic lava1 showing a columnar structure at the end of the point4 ,the columns are #bj inches in diameter1 and are inclined about #bj degrees from the vertical in such a direction that it may be inferred that the original flow1 doubtless submarine1 descended at that angle from ,n4,n4,w4 ,the dark grey rock of the columns 7spec4 grav4 #bgf7 has a fair amount of interstitial glass1 whilst a blackish compact rock 7spec4 grav4 #bgh7 that represents apparently a more superficial part of the flow has an abundance of smoky glass in the groundmass4 ,these rocks are basaltic andesites and are neither vesicular nor scoriaceous1 and come near the basalts of the ,kiombo flow which1 however1 contain some olivine 7see page #ib74 ,they are semi-ophitic and are referred to genus #ba of the augite-andesites which is described on page #bhc4 ,,na ,,raro4 ,in ,na ,raro we have one of the most interesting of the isolated hornblende-andesite mountains of ,vanua ,levu4 ,unlike ,vatu ,kaisia1 which often eludes the observation1 ,na ,raro is visible from most points of view4 ,it is double-peaked1 the two peaks lying in a north and south line and rising precipitously4 ,it is this feature that gives the mountain such a variety in its profile4 ,from the north and south it appears as shown in the accompanying sketch as a sharp conical peak4 ,from the north-east and south-east1 as illustrated in the two other sketches1 it has the form of a blunt or square-topped mountain2 and its true shape is only shown when it is seen from the east or west4 ,in the photograph here reproduced which was taken about #a miles to the south-west1 the two peaks are with difficulty distinguished4 7,see frontispiece47 ,not many ascents have been made of these precipitous peaks4 ,mr4 ,a4 ,barrack1 who kindly supplied me with some information about it1 made the ascent some years ago2 and ,mr4 ,blyth 7871 a magistrate1 also reached the top4 ,there are stories of some big officials being hauled up in baskets2 and the natives told me of a white man who was seized with a shivering-fit when he arrived at the summit4 ,it is certainly a rather hazardous climb2 but the safest plan is to resign oneself into the hands of the natives1 who 8bundle0 one up in an expeditious1 if not in a very ceremonious1 fashion4 ,nareilangi1 near the foot of the mountain on the north side1 is a convenient starting-point1 and half a dozen stout ,fijians will not prove too many to assist the climber in the difficult parts of the ascent4 ,since the top usually becomes clouded as the day progresses1 it is best to spend a night in a cave about #a1djj feet above the sea from which the ascent can be made in the early morning4 ,the view from ,na ,raro is panoramic and extends over a large part of the island from ,naivaka to ,savu-savu4 ,illustration3 ,,profiles ,,of ,,na ,,raro4 ,from the south off ,kumbulau ,point4 ,from the north in the ,ndreketi ,plains4 ,from the ,north-east4 ,from the ,east-south-east4 ,na ,raro rises up to a height of #b1dbj feet in the midst of a region of basic rocks4 ,agglomerates and coarse tuffs formed of aphanitic augite-andesites prevail in the broken country on the north and west sides towards ,nareilangi and ,ndrawa4 ,immediately south rises the ,tavia ,range with its basaltic andesites and overlying palagonite-tuffs2 whilst on the east lies a spur of this range4 ,nareilangi1 the village from which the start is made1 is about #b miles distant from ,na ,raro1 and though situated in the heart of the island it is only about #ajj feet above the sea4 ,the track first passes through a district of foraminiferous tuffs and clays reaching up to #bjj or #bej feet4 ,afterwards a broken country extending up to #hjj feet is traversed4 ,here prevail agglomerates and tuff-agglomerates derived from aphanitic augite-andesites4#eh ,one then descends into a valley about #fjj feet above the sea1 and from this place the ascent of the mountain proper begins4 ,the ascent at first is fairly steep1 dacitic tuffs prevailing up to #a1jjj or #a1ajj feet above the sea and forming in places precipitous cliff-faces4 ,large masses of hornblende-andesite lie on the slopes4 ,the dacitic tuffs distinguish ,na ,raro from all the other peaks of hornblende-hypersthene-andesite rocks that ,i examined4 ,they seem generally to have been stripped off by the denuding agencies2 and only at times1 as around the slopes of ,ndrandramea and ,thokasinga1 are to be found the remains of agglomerates of the same formation4 ,in the case of ,na ,raro1 however1 the tuffs differ somewhat in their components from the rocks forming the mountain mass4 ,the tuffs are derived from a hornblende-andesite of dacitic type2 whilst the massive rocks of the mountain are of hornblende-hypersthene-andesites1 without porphyritic quartz1 but approaching the dacitic habit4 ,the tuffs of ,na ,raro1 which are sometimes compacted and at other times rather friable1 do not display bedding4 ,they contain a little lime2 but ,i found no tests of foraminifera4 ,they are composed of fragments1 up to a centimetre in size1 of a dacite displaying brown hornblende1 plagioclase1 and quartz in a microfelsitic groundmass1 together with a few fragments of a semi-vitreous basic andesite4 ,above #a1ajj feet the tuffs give place to the massive hornblende-hypersthene-andesite4 ,at an elevation of #a1dej feet1 a shoulder of the mountain is reached1 near the top of which is the cave above mentioned4 ,crossing the shoulder one descends for #ajj or #aej feet into a gap1 thus reaching the foot of the precipitous northern peak1 which rises up like a wall for a height of from #ijj to #ajjj feet overhead4 ,it is in mass of the andesite just mentioned1 many of its faces presenting inaccessible cliffs displaying seemingly no structure4 ,this peak is somewhat lower than the southern peak4 ,i placed its height at #b1bgj feet1 which1 taking the total elevation of the mountain at #b1dbj feet1 as given in the chart1 makes the difference #aej feet4 ,a deep and broad cleft1 that goes half-way down the mountain1 separates the two peaks4 ,the southern one1 which appears to be inaccessible1 is evidently formed of the same acid andesite4 ,these hornblende-andesites1 with or without porphyritic quartz1 appear to be for the most part restricted to the immediate vicinity of ,na ,raro1 except to the south-west1 where at a distance of about a mile and a half from the mountain at an elevation of #ejj feet occur a rubbly hornblende-andesite and agglomerates of the same materials4 ,though the rock is of the ,na ,raro type1 its presence here is suggestive of a distinct vent of small size1 of which most of the traces have been swept away during the emergence of the island4 ,about half a mile south-east of this locality at an elevation of #dej feet occur some singular banded palagonite-tuffs which1 although they do not show foraminifera in the section examined1 contain a little calcite and are probably of submarine origin4444 ,in this locality ,i found a large white mass1 measuring #d #d #e feet1 formed of a siliceous rock appearing in thin sections as granular chalcedonic quartz 7see page #cee74 ,the hornblende-andesite of ,na ,raro1 as in the case of the rocks of most of the other peaks of acid andesites1 has its peculiar characters4 ,it differs1 for instance1 from that of ,vatu ,kaisia in the larger grain of the felsitic groundmass 7,n4 ,r4 #jba mm42 ,v4 ,k4 #jac mm471 in the absence or rarity of phenocrysts of rhombic pyroxene1 in its lower specific gravity 7#bf ,n4 ,r43 #bg ,v4 ,k471 in the presence of a little interstitial glass1 and in other particulars4 ,both1 however1 belong to the sub-class of hornblende-hypersthene-andesites1 and are described on page #cja4 ,in the ,na ,raro rock the rhombic pyroxene is represented in the groundmass4 ,with regard to the relative age of ,na ,raro ,i am inclined to think that it is the most recent of the acid andesite peaks of the island4 ,neither vitreous nor vesicular rocks came under my notice in its vicinity2 whilst the tuffs that clothe its lower slopes are non-pumiceous1 though of dacitic origin1 but containing also a few fragments of a semivitreous basic andesite showing tiny felspar lathes and augite-granules4 ,since the everywhere prevailing submarine palagonite-tuffs and foraminiferous clays do not extend over its area1 we may assign to it a later date4 ,it is evidently also posterior in time to the basaltic andesites and aphanitic augite-andesites around1 which are covered by these submarine deposits4 ,relatively recent as it apparently is1 this mountain bears the impress of a high antiquity4 ,there is nothing to indicate that this 8core0 of a volcanic mountain belonged to a subaerial vent4 ,na ,raro has shared in all the later stages of the submergence and emergence of the island4 ,though it presents the final page in the history of the hornblende-andesite volcanoes1 that chapter has been for unknown ages closed4 ,,the ,,na ,,raro ,,gap4--,between the ,tavia and ,va-lili ,ranges there is a break in the mountainous backbone of the island1 to which ,i have given this name4 ,the greatest elevation is probably not over #hjj feet4 ,it is from the south side of this watershed that the ,lango-lango river takes its rise4 ,,chapter ,,ix ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,basaltic ,,lowlands ,,of ,,sarawanga ,,and ,,ndreketi4 ,,one of the most striking features of the north side of the island is the extensive undulating plain that stretches from the ,lekutu river to near ,sealevu on the head-waters of the ,ndreketi1 a distance of almost #cj miles4 ,in its western half this plain slopes gradually to the sea-coast1 where it is bordered by a broad belt of mangroves4 ,in its eastern half1 from the mouth of the ,ndreketi eastward1 the lofty ,nawavi coast range intervenes between it and the sea-shore4 ,its breadth varies usually between #d and #f miles1 and its elevation1 though it reaches a maximum of about #cjj feet1 is as a rule between #ajj and #bjj feet above the sea4 ,over nearly all its area it presents the dried-up and scantily vegetated appearance of the 8talasinga0 regions4 ,it is an open country mostly clear of forest2 and it is to this character as well as to its peculiar vegetation that it in some measure owes its barren look4 ,amongst the bracken1 grass1 and tall reeds 7,eulalia japonica7 that clothe much of its surface flourish the ,pandanus1 the ,casuarina1 and the ,cycad1 which give a special physiognomy to the whole area2 whilst several sea-side plants1 as ,ipomea pes capr1 ,morinda citrifolia1 ,cerbera odollam1 c41 have spread themselves far and wide over its extent4 ,it is traversed by the rivers ,ndreketi1 ,sarawanga1 and ,lekutu1 the two first named being navigable for several miles1 as the tide ascends a long way from the coast4 ,in its essential characters this region corresponds with the ,mbua and ,ndama plains at the west end of the island1 which have been previously described4 ,wherever the rivers have worn channels of any depth1 basaltic rocks1 sometimes columnar in structure1 are exposed2 and over most of its surface the same rocks are displayed1 often much decomposed and developing a spheroidal character1 or lying in large blocks all around4 ,overlying the basaltic rocks in various localities occur foraminiferous clays and other submarine deposits4 ,this great region of plains is partially divided into two by the projecting mass of the dacitic district of ,ndrandramea1 the slopes of which descend to within #c or #d miles of the coast between the ,sarawanga and ,ndreketi rivers4 ,for convenience of description ,i will deal with these two sub-regions separately under the names of the ,sarawanga and ,ndreketi plains4 ,,the ,,basaltic ,,plains ,,of ,,sarawanga4-- ,these plains extend about #f miles inland to the village of ,tembe-ni-ndio on the head-waters of the ,sarawanga river4 ,the prevailing type of basalt in this region is a porphyritic olivine-basalt showing a few large crystals of glassy plagioclase and having a specific gravity of #bhd to #bi4 ,they are neither vesicular nor scoriaceous and are referred to genera #be and #cg of the olivine class4 ,the felspar-lathes of the groundmass average #b mm4 in length1 and there is a little interstitial glass4 ,they cannot often be distinguished in their characters from the olivine-basalt displayed in vertical columns1 #d to #e feet in diameter1 on the lower slopes of ,seatura at the back of ,tembe-ni-ndio 7page #fc74 ,it is highly probable that most of the basalts of these plains belong to lava-flows that descended from the great ,seatura vent4 ,in the lowlands it is much decomposed1 and a spheroidal structure is frequently developed during the disintegrating process1 just as has been noticed in the case of the ,mbua and ,ndama plains on the west side of ,seatura4 ,the rounded blocks that commonly occur on the surface may be regarded in each instance as the nucleus of a weathering spheroidal mass4 ,when this rock is exposed unaltered in the streams it is usually massive or non-columnar4 ,there is a less common type of basalt in this region which perhaps may represent the upper portion of these basaltic flows4 ,i found it exposed in the bed of the ,selesele river about half-way between ,lekutu and ,sarawanga and about #b miles inland1 where it formed vertical columns #a feet across4 ,it differs principally in the presence of a few small amygdules and in the greater amount of interstitial glass4 ,the columnar basalt that ,dana in the 8,geology of the ,united ,states ,exploring ,expedition0 describes as occurring at the mouth of the same river probably belongs to the same flow4 ,he remarks that a few hundred yards back from the 8,watering-place0 there is an exposure of columnar basalt1 the columns being vertical1 #a to #b feet in diameter1 and usually six-sided4 ,the incrusting submarine deposits found in patches over these plains are generally calcareous clay-rocks containing tests of formaminifera and often also univalve1 bivalve1 and pteropod shells4 ,they are referred to the foraminiferous mud-rocks described on page #cba4 ,such deposits are properly dark-coloured2 but as exposed at and near the surface they have often lost by hydration most of their lime1 and have acquired by the removal of the iron oxides a whitish or pale-yellow appearance1 whilst they have a peculiar soapy 8feel10 on account of which they are generally known as 8soapstone0 amongst the whites4 ,streams flowing through such districts have a somewhat milky colour4 ,these deposits are extensively represented on the slopes of the ,sarawanga valley1 and especially to the east of the town of that name4 ,they are well displayed on the way from ,sarawanga to ,tembe-ni-ndio1 and are also to be seen on the surface of the plains between ,lekutu and the ,mbua-,lekutu watershed to the southward4 ,in the vicinity of ,sarawanga they attain an elevation of #bjj feet above the sea2 but they may be traced in patches up to #ejj feet on the adjacent slopes of the acid andesite region of ,ndrandramea4 ,near the river1 and less than #ajj feet above the sea1 these deposits are in one place overlain by an agglomerate formed of large blocks1 #a to #b feet across1 of these ,ndrandramea andesites and dacites4 ,in another place1 near the town of ,sarawanga1 ,i found them exposed in the river-bank1 where they were covered over by a coarse palagonitic bedded tuff1 dipping gently eastward and somewhat calcareous4 ,from the character of the shells of marine univalves inclosed in this tuff1 it appears to have been formed in shallow water4 ,a very interesting display of these surface marine deposits occurs in the upper part of the ,sarawanga valley in the vicinity of ,tembe-ni-ndio4 ,here we have fine and coarse calcareous palagonitic tuffs1 containing tests of foraminifera1 associated with impure foraminiferal limestones4 ,they occur up to elevations of #cjj feet above the sea on either side of the ,sarawanga valley above this town1 incrusting on the north side the lower dacitic slopes of the ,ndrandramea district1 and on the south side the lower basaltic slopes of ,seatura4 ,at the bottom of the valley1 as in the rising ground between ,tavua and ,tembe-ni-ndio1 they conceal in part the basaltic rocks of the district4 ,near the last-named place1 on the right bank of the ,tembe-ni-ndio branch of the ,sarawanga river1 the foraminiferal limestones are displayed in low cliffs #ae to #bj feet in height4 ,they are sometimes earthy when they contain about #be per cent4 of lime1 and at other times more compact with about #de per cent4 of lime1 the residue being composed of palagonitic materials1 tiny fragments of minerals and of a basic rock1 c4#ei ,large shells1 of ,ostra and ,cardium are also contained in these limestones1 the valves being detached from each other4 ,the oyster shells project from the weathered surface2 and it is probable that the name of ,tembe-ni-ndio1 which signifies 8the shell of the oyster10 may be thus explained4 ,underneath the foraminiferal limestones in this locality occur bedded coarse tufaceous sandstones1 slightly inclined ,e4,n4,e41 and inclosing waterworn gravel and pebbles4 ,these low limestone cliffs1 although about six miles inland1 are not more than #abj or #acj feet above the sea4 ,in their face there is evidence of an old erosion-line of the river #aj or #aa feet above its present level4 ,by following up this branch of the river for a little distance ,i came upon an exposure of nearly horizontal bedded palagonitic tuffs on its floor and sides4 ,here a coarse tuff1 of which the larger fragments composing it range between #c and #e mm4 in size1 passes upward into a chocolate-coloured compact tuff-clay formed of the same materials1 the larger averaging #b or #c mm4 in size4 ,these tuffs are made up chiefly of a palagonitised vacuolar basic glass1 the vacuoles being filled with the alteration products4 ,the lower coarse tuffs contain very little lime1 probably not over #a per cent41 and exhibit no organic remains in the slide4 ,the upper fine tuffs have #c or #d per cent4 of lime1 and inclose numerous minute tests of foraminifera of the globigerina type1 their cavities being generally filled with palagonitic material4 ,further up the valley about a mile above ,tembe-ni-ndio1 and about #bej feet above the sea1 the impure foraminiferal limestones again appear2 but they here exhibit an important difference in texture4 ,in the groundmass of those of the lower locality1 the calcite is granular and loosely arranged1 or displays in an obscurely indicated mosaic the commencement of recrystallization4 ,in the case of those of the upper locality the calcitic material of the groundmass has more completely recrystallized1 and shows a fairly clear mosaic2 whilst in one place the rock was overlain or rather incrusted above by a layer1 #c inches thick1 of a white crystalline limestone1 looking like statuary marble1 and inclosing portions of a material like that of the rock beneath it4 ,this last1 when examined in the slide1 exhibits itself as formed in mass of crystalline calcite1 displaying a regular mosaic1 and inclosing small fragments of palagonitised materials and of minerals 7pyroxene7 such as are abundant in the rock below4 ,in places the grains of the mosaic are bordered by brown and black iron oxide4 ,it would1 therefore1 appear that a metamorphism has been in operation here1 and that the process which began with the recrystallization of the matrix in the lower rock is almost completed in the overlying thin layer where even most of the non-calcareous materials have disappeared4 ,no evidence suggestive of contact-metamorphism came under my notice in this locality4 ,these foraminiferal limestones are surface formations1 and it was in the uppermost portion that the metamorphism was most complete4 ,we here witness in operation the transformation of a rock containing #df per cent4 of carbonate of lime 7the residue of minerals1 palagonite1 c471 into a marble or crystalline limestone4 ,i gather that as in the instance of several of our old ,british limestones the change is a purely interstitial one1 and is not connected with thermal metamorphism4 ,these remarks on the basaltic plains of ,sarawanga and on their incrusting submarine deposits may be concluded with a brief reference to the siliceous concretions1 #b or #c inches across1 the silicified portions of corals1 and the fragments of clay iron-stone and limonite resembling hmatite1 that occur frequently on the surface4 ,they are common on the plains south of ,lekutu and between ,lekutu and ,sarawanga1 and up to elevations of #bjj feet in the foraminiferous clay district east of ,sarawanga1 where fragments looking like portions of the silicified branches of ,madrepores are to be found2 but they are not limited to such localities1 and may occur also where the surface is formed of decomposed basaltic rock4 7,these matters are generally discussed in ,chapter ,,xxv47 ,,the ,,basaltic ,,plains ,,of ,,the ,,ndreketi4--,this low-lying region of rolling 8talasinga0 country now serves as the basin of the ,ndreketi river1 the largest of the rivers of ,vanua ,levu4 ,it is usually elevated between #ajj and #cjj feet above the sea1 and its limits are well defined by the #cjj feet contour line in the map of the island4 ,on the east it is separated from the basin common to the ,wailevu and ,lambasa rivers by the ,sealevu ,divide1 which is described on p4 #acf4 ,on the west1 as before observed1 it is only in part distinguished from the basin of the ,sarawanga by the spur descending from the dacitic mountains of ,ndrandramea4 ,it meets the coast in the vicinity of the mouth of the ,ndreketi2 but for two-thirds of its length it is cut off from the sea by the great ,nawavi range4 ,it supports the characteristic vegetation of the 8talasinga0 or sun-burnt land4 ,whilst the ,pandanus and the ,casuarina are most conspicuous amongst the trees1 bushes1 herbs1 grasses and ferns predominate4 ,here the native ,ginger and the native ,turmeric with species of ,tacca are frequently to be recognised1 and the waste-land bushes of ,dodona viscosa and ,mussnda frondosa are abundantly to be found4 ,as in the ,sarawanga plains1 the basaltic rocks are here often overlain or incrusted by submarine deposits1 the former exposed in all the deeper river-beds1 the latter frequently displayed in the sides of their tributaries4 ,i will deal first with the basaltic rocks4 ,in the places where the surface deposits have been stripped off1 these rocks are generally exposed as decomposing boulders1 the spheroidal structure being well developed in the weathering process4 ,not infrequently1 however1 a rudely columnar structure is exhibited where the rivers have cut deeply into the basalt4 ,the columns that ,i observed were usually vertical4 ,in the river-bed at the landing-place at ,mbatiri1 for instance1 the columns are from #b to #c feet across and vertical4 ,as exposed in the river-crossing about a mile above this town they are #ab to #ae inches in diameter and also vertical4 ,however1 at ,na ,kalou1 a coast village about #a miles east of the mouth of the ,ndreketi1 where there is an unexpected exposure of basalt1 the columns1 about a foot in diameter1 are inclined at an angle of about #bj from the vertical and face to the north4 ,these rocks are1 as a rule1 compact1 only showing a typical scoriaceous structure in the case of specimens obtained near the foot of ,nakambuta1 an isolated hill about three miles to the southward of ,natua1 which probably represents a vent of more recent times4 ,often1 however1 they have a pseudo-vesicular appearance1 from the occurrence in the midst of the patches of interstitial glass of minute irregular cavities that seem to have been formed during the last stage of consolidation of the magma4 ,the prevailing type of basalts is a blackish1 doleritic1 semi-ophitic rock without olivine1 with specific gravity #bgh to #bhj4 ,they are characterised by the length of the felspars of the groundmass 7#bb-ce mm471 by the large size of the augite granules 7#a-c mm471 and by the quantity of dark interstitial glass4 ,they present two forms1 one with and the other without plagioclase phenocrysts4 ,the first kind is referred to genus #i of the augite-andesites 7page #bgb71 some of the specimens being referred to the porphyritic sub-genus1 and others to the non-porphyritic sub-genus1 according to the size of the plagioclase phenocrysts4 ,the second kind1 without felspar phenocrysts1 belongs to genus #ab of the same class 7page #bge74 ,a good example of the porphyritic rocks is afforded in the large blocks lying in the stream-beds during the first half of the way from ,ndreketi to ,sarawanga4 ,it may be pointed out here that these doleritic1 semi-ophitic basaltic andesites of the ,ndreketi plains differ conspicuously from the prevailing type found on the slopes of ,seatura1 on the ,sarawanga and ,mbua plains1 and on the ,wainunu table-land4 ,there we have1 as a rule1 olivine-basalts1 having a specific gravity of #bhf to #bij1 and showing but scanty interstitial glass1 the felspars of the groundmass being on the average not over #b mm4 in length1 whilst the augite granules are1 as a rule1 only #jb-jc mm4 in diameter1 and the ophitic structure is infrequent4 ,the submarine deposits1 consisting of foraminiferous clays and coarser tuff-sandstones1 the former being usually beneath1 are found at intervals all over this area4 ,they occur inland as far as ,vuinasanga and ,nareilangi1 near the base of the mountains of ,va ,lili and ,na ,raro1 reaching as high as #cjj feet1 their place being taken on the mountain slopes by coarser tuffs and agglomerates4 ,when not weathered they are more or less calcareous1 and contain occasionally marine molluscan shells1 whilst palagonitic debris enter largely into their composition4 ,the foraminiferous clays1 often much bleached by hydration1 are well represented around ,mbatiri and in the districts between that town and ,natua and ,nareilangi4 ,they are relatively deep-water deposits1 and belong to the type described on page #cbc4 ,others1 again1 as exposed in the banks of the river at ,natua1 are chocolate coloured and of the kind referred to in detail on page #cce4 ,these foraminiferous clays in the region between ,natua and ,mbatiri are overlain in places by coarse1 almost brecciated1 tuffs1 formed in part of the debris of acid andesites1 such as compose the not far distant mountain of ,na ,raro4 ,since the massive basaltic rocks are exposed in all the deeper rock channels of these plains1 it is apparent that the overlying submarine deposits can possess no great thickness4 ,probably they are never #ajj feet thick1 and usually far less4 ,in many places1 through their denudation1 the underlying basaltic rocks are exposed1 and in a decomposing condition largely form the surface4 ,these deposits as a rule display bedding1 the beds being horizontal or at least only inclined #b or #c degrees4 ,this horizontality is a nearly constant feature of these submarine beds1 as they overlie the basaltic rocks of the plains2 and it is a feature we should expect to find where there has been emergence rather than upheaval4 ,siliceous concretions and silicified coral fragments1 so characteristic of the surface of some of these plains of ,vanua ,levu1 did not frequently come under my notice here4 ,they1 however1 occur occasionally1 as in the district between ,nanduri and ,natua4 ,,the ,,nawavi ,,range4 ,with this remarkable coast range1 which fronts the ,mathuata sea-border for a distance of #ab or #ac miles between ,ravi-ravi ,point and ,nanduri1 ,i have unfortunately but scant acquaintance4 ,it attains its maximum elevation in ,mount ,nawavi of #b1bch feet1 and is described by ,mr4 ,j4 ,p4 ,thomson1#fj who surveyed this coast1 as broken in two nearly opposite ,niurua1 the pyramidal mountain of ,koro ,navuta rising in the gap4 ,various other peaks1 besides that of ,nawavi1 are marked in the latest ,admiralty chart2 they vary in height from #a1jjj to #a1gjj feet4 ,as this range lies only a mile or less back from the beach1 it gives to the sea-border a bold and often precipitous appearance1 which is well shown in an illustration in ,wilkes' ,narrative of the ,united ,states ,exploring ,expedition 7iii4 #bbf74 ,basic rocks probably prevail in this range4 ,when ,i ascended its eastern spurs from ,nanduri1 and reached a height of #hjj feet1 only basic tuffs and agglomerates came under my notice4 ,from ,dana's remarks#fa it is to be inferred that the 8frowning bluffs0 opposite ,mathuata ,island are of similar formation2 and it would seem that the rugged black stones1 described in the ,admiralty ,sailing ,directions#fb as topping the hills behind ,ravi-ravi ,point1 are of the same basic character4 ,from its contour and profile ,i would gather that1 as in the great mountainous ridges that constitute the backbone of the island between ,va ,lili and ,mount ,thurston1 palagonitic tuffs and clays of submarine origin will1 together with volcanic agglomerates1 be found far up the slopes of this range1 and that the axis will prove to be largely composed of massive basic rocks4 ,the hot springs referred to by ,thomson and others as occurring at the foot of the north and south slopes1 namely at ,vatuloaloa1 ,nambuonu1 and in another unnamed inland locality1 are briefly mentioned on page #ca4 ,,the ,,sealevu ,,divide4--,this broad range which separates the ,ndreketi and ,lambasa basins is an offshoot from the central mountains at ,sealevu and reaches the coast just east of ,nanduri4 ,its highest part according to the elevation given in the ,admiralty chart is #a1dcg feet4 ,the road from ,sealevu to ,nanduri1 which crosses its broad level summit for a distance of about three miles1 does not rise over #a1ajj feet4 ,between #hjj and #a1ajj feet are exposed calcareous tuffs and clays all largely made up of palagonitic materials4 ,the coarser might be described as sandstones4 ,the clays have #ab per cent4 of lime and are foraminiferous and are of the type described on page #cba4 ,the rocks displayed on the lower northern slopes on the way to ,nanduri are at first the same submarine deposits1 and afterwards decomposing basaltic andesites4 ,it is apparent that in the central elevated part of this range there are hills of volcanic formation more or less completely buried beneath these deposits4 ,,the ,,district ,,between ,,nanduri ,,bay ,,and ,,wailevu ,,river ,the sea-border between ,nanduri ,bay and ,middle ,point1 nearly four miles to the east1 consists of a fringe of lowland margined by the mangrove-belts and banked by a line of hills between a quarter and two-thirds of a mile inland4 ,these hills form a continuation of the ,nawavi coast range of mountains extending from ,ravi-ravi ,point to ,nanduri4 ,they attain their greatest height in the case of ,ulu-i-sori1 a cockscomb-like peak #a1ada feet above the sea4 ,another of these hills1 ,vatu-tangiri1 is capped by a remarkable obelisk-like rock4 ,behind this coast range lies a hill with an elevation of nearly #a1djj feet4 ,the rocks exposed for the first mile or two along the coast east of ,nanduri are agglomerates and basic tuffs4 ,the blocks of the agglomerates1 however1 are made of an altered grey porphyritic rock which has the characters of a porphyrite of a rather acid type4#fc ,this composition of the agglomerate is quite exceptional and indicates the antiquity of the volcanic rocks in this locality4 ,farther along the coast the typical agglomerates occur1 where the blocks1 #c to #aj inches across1 are composed of the usual semi-vitreous black basaltic rock showing plagioclase phenocrysts4 ,nearer ,middle ,point a decaying doleritic basalt is displayed at the surface4 ,it is similar to the prevailing rock of the ,ndreketi plains1 and is referred to the ophitic rocks forming genus #i of the augite-andesites4 ,the elevated promontory of ,middle ,point is a prolongation of a spur of ,ulu-i-sori4 ,where it is crossed by the road it is about #cej feet above the sea4 ,on its west slopes are exposed yellowish-white tuff-like rocks1 evidently the prevailing basic clay-tuffs which have become bleached through the hydration accompanying the weathering process4 ,beneath these deposits lies an amygdaloidal augite-andesite which is bared in places4 ,the rock is semi-vitreous and the amygdules it contains are often a centimetre long4 ,they are composed of a white mineral with fibro-radiate structure and made up of needle-like prisms4 ,it gives off water1 but it is not easily fused1 and does not gelatinise in ,h,cl4 ,from the top of the promontory the road strikes inland in an east-south-east direction for ,tambia1 passing inside the coast range1 which is here #fjj feet in height1 and descending gradually through a region of basaltic andesite into the valley of the ,tambia river4 7,this rock1 which has a specific gravity of #bhd1 displays more or less parallel stout felspar-lathes1 #bc mm4 in length1 and has a little interstitial glass4 ,it belongs to genus #ac of the augite-andesites47 ,low hills shut in the little valley on all sides except where the river breaks through the coast range4 ,the town of ,tambia is not over #ajj feet above the sea4 ,about a mile to the north exist hot springs of considerable extent which are described on page #cb4 ,the road from ,tambia to the ,wailevu ,river traverses an undulating district varying from #ajj to #cjj feet above the sea4 ,a basalt containing a little olivine1 with a specific gravity of #bia1 is commonly exposed at the surface in a disintegrating condition4 ,here and there occur basic tuffs4 ,in one locality1 there is displayed a dyke-like mass in a small stream course1 #bjj feet above the sea1 of an altered grey and compact andesite marked with parallel red streaks or bands4 ,it is an aphanitic augite-andesite2 and is to be referred to genus #ac of the augite sub-class4 ,it displays closely crowded felspar-lathes1 #jg mm4 in length1 in flow-arrangement4 ,the bands are due to the gathering of the residual glass in streaks parallel to the flow4 ,chalcedonic flints1 some of them showing the agate-structure1 together with fragments of silicified corals1 are found occasionally on the surface in this district4 ,,the ,,lambasa ,,plains ,these remarkable inland plains1 about ten miles long and three to five miles broad1 are well described in the ,admiralty chart as a low undulating country covered with grass1 screw-pines1 and ,casuarina trees4 ,they are backed by the mountains forming the central axis of the island1 whilst broken groups of hills1 not usually more than #ejj or #fjj feet in height and attaining in ,ulu-i-,mbau an elevation of #a1afj feet1 intervene between them and the sea-border4 ,they are traversed by the ,wailevu1 ,lambasa1 and ,ngawa rivers which after breaking through the seaward hill-ranges pass through broad mangrove-belts to reach the coast4 ,the tide ascends these river-courses for several miles2 and in the case of the ,lambasa river boats can follow its winding course for ten miles penetrating into the heart of the plains4 ,much of this level inland region is less than #ajj feet above the sea2 whilst the contour line of #cjj feet by which the region is defined in the map attached to this book fairly well indicates the higher levels4 ,the features which we have described in the instances of the ,sarawanga and ,ndreketi plains are in the main reproduced in the ,lambasa region2 but in the last-named each of the three rivers has a system of hot springs along its course1 namely 7as described in ,chapter ,,iii471 at ,na ,kama on the ,wailevu ,river1 at ,vuni-moli on the ,lambasa ,river1 and at ,mbati-ni-kama on the ,ngawa ,river4 ,basaltic andesites1 often exposed at the surface in a decomposing condition1 form the foundation of the plains4 ,they are overlain by submarine clays containing pteropod shells and tests of foraminifera2 and over these in their turn coarse palagonitic tuffs and agglomerate-tuffs are found in places4 ,formations still more recent are represented by elevated reef-rock on the seaward side of the hills that bound the plains4 ,nodules of chalcedony1 silicified corals1 and other siliceous rocks1 together with fragments of impure limonite1 lie on the surface over much of this region4 ,the basaltic rocks of this region rarely show olivine1 and belong as a rule to the basaltic andesites1 being referred to genera #ac and #ba of the augite-andesites1 the specific gravity being about #bh4 ,the felspar-lathes1 #ab to #ad mm4 in length1 are in flow-arrangement1 and the augite is at times semi-ophitic2 whilst there is a little interstitial glass4 ,the basic rocks prevailing between ,vatu-levoni and ,vandrani belong to genus #ac of the augite-hypersthene-andesites and have a groundmass of much finer texture1 the felspars only measuring #je mm4 ,their specific gravity ranges between #bg and #bge4 ,the overlying foraminiferous and pteropod clay rocks1 the so-called 8soapstone10 are exposed over large areas of the surface4 ,a good idea of the important part they take in the formation of the lower plains may be formed by visiting the hot springs of ,vunimbele1 close to ,vuni-moli1 which issue from the side of a deep trench cut into these deposits4 ,as generally displayed at the surface1 they have been subjected to so much hydration in the weathering process that they appear as yellowish-white clay-rocks deprived of their lime2 and it is only now and then that the remains of foraminifera and pteropods can be detected4 ,they are1 however1 fairly well preserved around the base of ,ulu-i-mbau in the vicinity of ,koro-wiri1 where they contain1 besides the shells of pteropods and foraminifera1 portions of decaying coral1 and extend to #bjj feet and over above the sea4 ,here they are overlain by rather coarser basic tuffs of mixed character1 containing #e or #f per cent4 of carbonate of lime and some palagonite1 which ,i followed as high as the track lay1 rather over #ejj feet above the sea4#fd ,the reef-limestones1 already noticed as exposed in the low hills between ,wailevu and ,lambasa1 lie a mile or two inland and reach to #ajj feet above the sea4 ,the fragments of siliceous rocks1 which with occasional bits of impure limonite1 occur at intervals all over the surface of these plains and largely form the gravel and pebbles in the river-beds1 include nodules of chalcedony1 fragments of jasper or iron-flint1 white quartz-rock formed of chalcedonic silica1 silicified corals1 c4 ,they are especially frequent in the vicinity of ,nasawana and ,koro-utari1 and include fine specimens of agates and of onyx4 ,,chapter ,x ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,va-,,lili ,,range ,,this range extends from the ,na ,raro ,gap before mentioned to the ,ndreke-ni-wai river4 ,it is partly isolated on the north-east from the ,korotini ,range1 the extension eastward of the mountainous axis of the island1 by a depression or saddle which at its lowest part is not more than #a1bjj or #a1cjj feet above the sea2 but there is no real break in the line of mountains4 ,it is1 however1 convenient to make this distinction1 and ,i have named the dip between the two ranges1 the ,waisali ,saddle4 ,the range now to be described attains its greatest elevation in the summit of ,va-lili1 which is #b1icj feet above the sea4 ,there are two or three other peaks that exceed #b1jjj feet1 and much of the range is not under #a1gjj feet4 ,my acquaintance with this range is not extensive2 but it will serve to illustrate its general geological structure4 ,the summit of ,va-lili is very conspicuous from most points of view4 ,from the north1 east1 and south-east1 it has a remarkable broad and square-topped profile with a little conical elevation in the centre4 ,from the south-west1 it displays a different outline with a solitary squarish block on the top1 and this is the form most familiar to the navigator4 ,unfortunately1 for reasons given below1 ,i did not quite reach the summit1 and although ,i was able to obtain sufficient data for forming a general idea of the structure of this part of the range1 the structure of the actual summit has yet to be ascertained4 7#a7 ,,ascent ,,of ,,va-,,lili ,,from ,,narengali4--,this village1 which is elevated #djj feet above the sea1 lies about two miles in a direct line1 ,n4,n4,e4 from the peak4 ,in traversing the intervening country1 one crosses the ,loma-loma ridge1 elevated #a1jjj feet1 on the top of which was once situated the village of ,loma-loma visited by ,horne in #ahgh4 ,the rocks exposed on the surface are scanty1 a hard palagonite-tuff1 which owes its induration to a calcitic cement1 occurring on the upper part of the ridge2 the original site of the village being marked by a large block of this stone4#fe ,the track then descends into the valley of the ,loma-loma river1 about #djj feet above the sea1 in the bed of which occur blocks of an amygdaloidal basaltic andesite1 containing phenocrysts of both rhombic and monoclinic pyroxene1 and referred to genus #a of the rhombic pyroxene andesites4 ,the amygdules are formed of calcite4 ,,profile-,,sketches ,,of ,,the ,,va-,,lili ,,range4 ,illustration3 ,view from the south-east near ,savarekareka4 ,illustration3 ,view from the south-west4 ,beyond the river the ascent of the northern slope of ,va-lili begins4 ,as high as #a1ajj feet occur basic agglomerates overlying fine and coarse palagonite-tuffs1 which are at times horizontally bedded1 the finer kinds being sometimes calcareous1 and like that of the ,loma-loma ridge above mentioned4 ,at #a1cjj feet is a line of tall cliffs which extend for some distance at intervals along the mountain-slope1 and are indicated by some fine waterfalls4 ,my track struck these cliffs at a place named 8,nangara-ravi0 7the leaning cave-rock7 where they have a height of #aej feet or more4 ,the tall cliff leans slightly forward1 so that it forms a shelter at its foot1 and hence the name4 ,it is composed of a tuff-agglomerate1 the blocks1 which are formed of a semi-vitreous basaltic andesite of the augite class1 being not generally more than #c or #d inches across4 ,these blocks1 which are rounded on the outer exposed side and angular on the imbedded side1 are inclosed in a hard1 probably calcareous matrix4 ,the whole face of the cliff has the appearance of having been worn smooth by attrition1 and there are not to be observed the projecting blocks from its surface which are so characteristic of other agglomerate-cliffs4 ,it shows no stratification2 but at its base flush with the cliff-face are large masses of a basic massive rock4 ,but few portions of rock have been detached from the cliff4 ,however1 ,i found in the midst of a huge fallen fragment of the agglomerate a dyke-like mass of a basaltic andesite1 which differs chiefly from the rock forming the blocks of the agglomerate in being more crystalline4 ,this dyke must have been about #ae feet thick4 ,having regard to these various features1 ,i am inclined to consider that this leaning cliff represents one side of a large fissure in the agglomerates which was occupied by a dyke4 ,reference has been above made to the fact that the agglomerates may be seen overlying the tuffs farther down the slope1 so that the conditions favourable for landslips exist4 ,i have shown on page #aaa that the origin of the ,mbenutha cliffs where agglomerates lie on clayey tuffs may be thus attributed to a landslip4 ,in the case of the ,nangara-ravi cliffs1 the occurrence of this fragment of a large basaltic dyke is of some importance in connection with the origin of the basic agglomerates of this locality4 ,the top of the mountain-ridge is about #gjj feet above ,nangara-ravi1 or #b1jjj feet above the sea4 ,the tuffs and agglomerates that once existed here have been stripped off to a great extent and the deeper rocks of the range are in part exposed4 ,the upper part of this ridge 7#a1gjj to #b1jjj feet7 is formed of a rubbly pitchstone where a basic glass has been broken up and then consolidated1 the interstices being filled up with palagonite as described in other cases on page #cac4 ,though non-vesicular1 it is just such a rock as one would expect to find on the surface of a lava-flow or on the sides of a dyke4 ,the crest of the range is here only a narrow ridge4 ,i followed it along in a north-west direction1 gradually ascending on the way1 and in time the rubbly pitchstone gave place to a hardened palagonitic clay rock1 which was observed as high as #b1cjj feet4 ,it apparently contains a little lime1 and probably was at one time foraminiferous2 but it is now much affected by hydration4 ,soon after this1 we arrived at the foot of the steep ascent leading to the summit of ,va-lili4 ,we were now rather over #b1djj feet above the sea2 but my natives refused to go on1 the heavy rain having made the slope too slippery for a safe ascent4 ,with much reluctance ,i retraced my steps2 and as the bad weather continued for several days after1 ,i did not make another attempt4 ,there would1 however1 be no difficulty in dry weather4 7#b7 ,,traverse ,,of ,,the ,,va-,,lili ,,range ,,from ,,the ,,old ,,site ,,of ,,loma-,,loma ,,to ,,waiwai ,,on ,,the ,,coast ,,of ,,savu-,,savu ,,bay4--,this route1 which was taken by ,mr4 ,horne1 the botanist1 in the reverse direction in #ahgh1 is thus described in his book1 ,a ,year in ,fiji 7p4 #ai73 8,the path1 rough and apparently not much used1 ran along streams1 up steep ascents and down awkward descents1 over slippery boulders and fallen trees1 up the sides and along the crests of densely wooded mountains40 ,ascending the north slope of the range ,i found at the ,tangi-nandreli cave1 which is #a1jej feet above the sea1 a palagonite-tuff-sandstone underlying the basic agglomerate4 ,this tuff1 which is of the type described just below1 does not effervesce with an acid1 and shows no tests of foraminifera when examined with a lens4 ,further up the slopes large masses of agglomerate occur4 ,at #a1cej feet ,i came upon a large mass of a fine-grained compacted palagonite-tuff made up chiefly of fragments of palagonitized vacuolar basic glass4 ,among the mineral fragments occur plagioclase1 augite1 and rhombic pyroxene1 and a little fresh olivine1 which is of very rare occurrence in these palagonite-tuffs4 ,it contains little or no lime1 and shows no tests of foraminifera in the slide4 ,the summit of the range is here about half a mile broad1 and is relatively level4 ,i placed its elevation at #a1gfj feet1 which is not far from ,horne's estimate of #a1hjj feet4 ,the southern slope1 which is the rainy side of the range1 is much cut up into gorges4 ,in the upper #bjj feet palagonite-tuffs1 similar to those above referred to1 are displayed1 and basic agglomerates occur lower down4444 ,this part of the range is remarkable through being completely covered over by palagonite-tuffs and agglomerates4 ,it has been pointed out above that this is not the case with the range close to the highest peak1 where the underlying rocks are in part exposed at the crest of the range4 7#c7 ,,the ,,eastern ,,peak ,,of ,,the ,,va-,,lili ,,range4--,this hill1 about #a1ajj feet in height1 overlooks the ,mbale-mbale branch of the ,ndreke-ni-wai river4 ,at its foot near the river there is exposed at the roadside a rubbly pitchstone formed of a basic glass1 inclosing porphyritic crystals of plagioclase1 augite1 and olivine1 which is described on page #cac4 ,here also occurs an agglomerate made up of blocks of a semi-vitreous basaltic andesite 7sp4 gr4 #bgh71 showing prismatic pyroxene in the groundmass1 and referred to genus #bj of the augite-andesites4 ,the upper part of the hill displays the same agglomerate1 and a tuff-agglomerate in which small fragments of the basaltic andesite are inclosed in a matrix largely made up of fine debris of basic glass4 ,there protrudes through these detrital rocks at the top of the hill a broad dyke-like mass of the same basaltic andesite that forms the agglomerate around2 and the structure of the hill is thus displayed as that of an old volcanic neck4 ,it has evidently an axis of massive basaltic rocks1 more or less covered over with agglomerates and tuffs4 7#d7 ,,the ,,nambuni ,,spur4--,this singular spur runs down to the coast between ,waiwai and ,wailevu2 but it is partly separated by a deep gap from the main range4 ,it attains a height of #eej to #fjj feet1 and has two little peaks which the natives call ,vatu-tolutolu and ,vatu-tangitangiri4 ,its position is shown in one of the profile-sketches of ,va-lili1 given on page #ada4 ,the crest of the spur is formed by a dyke-like mass1 #be to #cj feet thick1 which is composed of a basic agglomerate passing down into a palagonite-tuff4 ,the blocks of the agglomerate are composed of a semi-vitreous basaltic andesite1 showing minute felspar-lathes in flow-arrangement in an abundant smoky glass1 the fine pyroxene being not differentiated4 ,the tuff1 into which the agglomerate passes down is non-calcareous1 and displays no organic remains4 ,it is1 however1 composed of fragments1 which do not generally exceed a millimetre in size1 of palagonitised vacuolar glass1 basic andesites1 plagioclase1 monoclinic and rhombic pyroxene1 c4 ,this dyke-like mass forms the axis of the ridge and protrudes vertically about #ajj feet1 the bulk of the spur being composed of a compacted brecciated palagonite-tuff made up mainly of fragments a centimetre in size1 of a basic vacuolar glass1 sometimes fibrillar1 which is extensively palagonitised4 ,the filling up of a fissure in a mass of tuff-breccia by palagonite-tuffs and agglomerates probably occurred during the submergence1 the original dyke-rock having been removed by marine erosion4 ,after the emergence the subaerial denuding agencies reshaped the surface1 and as a result of the less yielding character of the materials filling the fissure1 they protrude as a dyke-like mass from the crest4 ,in a cliff-face of the adjacent main range there are displayed an agglomerate of basaltic andesite and a pitchstone-breccia1 composed of fragments of but little altered basic glass1 the interstices being filled up with palagonite4 ,in the case of the ,kiombo flow ,i have endeavoured to explain the origin of a closely similar pitch-stone-breccia 7page #ib74 7#e7 ,,the ,,sea-,,border ,,and ,,the ,,low-,,lying ,,districts ,,at ,,the ,,base ,,of ,,the ,,va-,,lili ,,range4--,it may be generally remarked that palagonite-tuffs and clays1 often foraminiferous1 prevail in these localities4 ,thus in the sea-border between ,waiwai and the mouth of the ,ndreke-ni-wai basic agglomerates are displayed where the mountains approach the coast2 but further west a broad tract of undulating land1 elevated usually #ajj to #cjj feet1 intervenes between the range and the sea-border1 and here coarse and fine palagonite-tuffs predominate4444 ,on the north-west the foraminiferous tuffs and clays of the ,ndreketi plains approach the ,va-lili range in the vicinity of ,vuinasanga1 and extend for at least #bjj or #cjj feet up its sides4444 ,at the east end of the range1 where the slopes descend to the plains of the ,waisali valley1 a little west of ,mbale-mbale1 there are exposed bedded palagonite-tuffs1 tilted up at an angle of about #bj to the south-west4 ,they contain a little lime and display microscopic tests of foraminifera1 the palagonite being minutely vacuolar1 the cavities also being filled with the altered glass4 ,i noticed those submarine deposits at an elevation of #ajj feet1 but probably they reach much higher4 ,the inference to be drawn from the data above given concerning the ,va-lili range seems clearly to be this4 ,we have here indicated the emergence of a submarine mountain-ridge covered over with palagonite-tuffs and agglomerates1 the last being uppermost4 ,these coverings have been in places stripped off by the denuding agencies and the underlying massive basic rocks exposed4 ,these rocks1 however1 vary much in texture1 some being vitreous1 as in the case of the pitchstones1 others hemi-crystalline as in the case of the basaltic andesites2 and it is to be gathered from this and other similar indications that different submarine vents were formed along a fissure or fissures at the sea-bottom4 ,no evidence of subaerial eruptions came under my notice4 ,after the vents became extinct they were buried beneath the palagonite-tuffs and agglomerates4 ,during and after the emergence the denuding agencies reshaped the surface of the range and left but little of its original form4 ,since it is my object to build up a theory of the origin of the ridge-mountains as ,i proceed with the systematic description of the island1 it will be here convenient to follow up the preceding remarks on the ,va-lili ,range by a preliminary reference to the great ridge district lying east of it4 ,when a panoramic view of this region is obtained1 one observes a series of lofty ridges more or less parallel and running about ,n4,w4 and ,s4,e4 ,there are the ,va-lili1 ,narengali1 and ,sealevu ridge-mountains with lesser ridges between4 ,the intervening valleys are elevated about #djj feet above the sea1 whilst the mountains rise up to over #b1jjj feet4 ,in many localities this configuration of the surface would be attributed mainly to subaerial denudation4 ,in this island ,i will endeavour to show that these mountain-ridges existed before the emergence4 ,they do not owe their form to the rivers that flow through the valleys1 though no doubt river-erosion has brought these features into greater relief4 ,in ,vanua ,levu1 as there will be frequent occasion of showing1 rivers often flow in valleys that they have not made4 ,this is especially pointed out on page #aea2 and it is necessary to emphasise it here1 before proceeding farther with the description of the geological structure of the mountain-ridges4 ,,the ,,waisali ,,saddle ,this saddle1 which connects the ,va-lili and the ,koro-tini ranges1 has probably a minimum elevation of not over #a1bjj or #a1cjj feet4 ,to understand this district thoroughly a regular survey is1 however1 necessary4 ,it is only at times in this densely wooded range that a view of the surrounding country is obtained2 but in spite of this drawback ,i was able by a diligent use of watch1 aneroid1 and prismatic compass1 to obtain a fair general notion of the surface-configuration4 ,the track that proceeds westward from ,waisali to ,narengali leads also to the villages of ,na ,sinu and ,sealevu4 ,about #a or #b miles from ,waisali1 the track branches off to the westward for ,narengali and to the northward for ,na ,sinu and ,sealevu4 ,after half an hour's walk along this last-named path1 one comes to a place where at an elevation of about #ijj feet it branches off to the left for ,na ,sinu1 crossing the lowest part of the saddle1 and to the right for ,sealevu across the ,koro-tini ,range4 ,it may here be remarked that since the natives are gradually abandoning their mountain-villages and are settling at the coast1 many of the mountain-tracks used by me will before long be overgrown and forgotten4 ,in taking the path from ,waisali to ,narengali one soon enters the hilly country where large masses of basic tuffs and basic agglomerates1 the last formed of blocks of a compact basaltic andesite1 occur on the surface up to #gjj or #gej feet above the sea4 ,the rock just named has a specific gravity of #bhd1 and since it displays rhombic pyroxene amongst its phenocrysts1 it is placed in genus #a of the hypersthene-augite andesites4 ,above this elevation1 and as far as the top of the range1 #a1hjj-a1ijj feet above the sea1 porphyritic basaltic andesites1 having a specific gravity of #bh1 prevail at the surface4 ,they display small porphyritic crystals of plagioclase1 augite1 and rhombic pyroxene in a groundmass composed of small felspar-lathes1 prismatic pyroxene1 and much smoky glass1 and are referred to genus #e of the same pyroxene andesites4 ,it is probable1 judging from one of these exposures1 that such rocks are dyke-like masses3 but on account of the thick soil-cap it is not possible to obtain a good view of them4 ,in the stream-courses occur large blocks of altered basaltic andesites of the propylitic type1 having a specific gravity of #bfd to #bgj1 and exhibiting abundant alteration products1 such as calcite1 viridite1 c4 ,these propylites1 ,i presume1 constitute the deeper portion of the range4 ,it will often be necessary to distinguish between the altered basaltic andesites1 such as are above referred to1 and the relatively fresh rocks of the same type4 ,the former are light coloured 7sp4 gr4 #bf to #bge71 and are only exposed in gorges and stream-courses that deeply score the mountain-slopes4 ,the latter are blackish 7sp4 gr4 about #bh71 and at times penetrate the covering of tuffs and agglomerates4 ,descending the opposite or north-west side of the saddle-range1 one finds the same basic andesites1 both fresh and altered1 down to about #a1ajj feet above the sea4 ,then the track leads one down a precipitous slope into the picturesque gorge traversed by the head-waters of the ,narengali ,river4 ,at its lower end the gorge opens out into the broad ,narengali valley1 and here the dense forest of the higher districts gives place to the scanty vegetation of the 8talasinga0 region4 ,the rocks exposed in the sides of the gorge are basic agglomerates overlying palagonitic tuffs of mixed composition and evidently sedimentary4 ,on the bottom lie huge masses1 some of them #gj or #hj tons in weight1 of altered grey aphanitic or non-porphyritic augite-andesites1 penetrated in some cases by thin veins of white quartz1 and at times displaying a rudely columnar structure1 the columns being #ab to #ad inches across4 ,sometimes the alteration is mainly confined to the filling of the fissures with chalcedonic quartz1 minute nests of the same material occurring in the groundmass4 ,at other times the small augite granules are also decomposing4 ,the specific gravity varies from #bfd to #bgc2 the rocks being referred to genus #af1 species ,a1 of the augite-andesites4 ,occasional detached masses of a propylitic basic andesite1 displaying porphyritic plagioclase and pyroxene1 also occur in this gorge1 the felspar phenocrysts being largely occupied by calcitic and other alteration products1 whilst much viridite occurs in the groundmass4 ,it exhibits both monoclinic and rhombic pyroxene2 and on account of the prism form of the groundmass pyroxene it is placed in the #bnd sub-order of the hypersthene-augite andesites4 ,these altered rocks are deep-seated intrusive masses that were originally covered over by the basic agglomerates and palagonite-tuffs exposed in the sides of the gorge4 ,below the gorge there is an extensive exposure in the sides and bed of the river of light-coloured calcareous tuffs which were originally composed of palagonitic materials2 but owing partly to hydration1 and partly to other secondary changes1 the original structure is much disguised4 ,crossing the river in the midst of these tuffs there is a dyke1 #ae feet thick1 formed of a propylitic basaltic andesite1 a semi-vitreous rock in which calcitic and zeolitic materials have been developed in quantity4 ,the dyke1 which is not columnar1 is steeply inclined at an angle of #de to the north-east4444 ,further down the river-valley as far as ,narengali1 occur basic tuff-agglomerates4 ,,the ,,tract ,,of ,,nakambuta ,this is a tract of broken country that projects from the mountainous backbone of the island 7between the ,va-lili and ,koro-tini ranges7 into the heart of the ,ndreketi plains in the vicinity of ,natua4 ,as limited by the #cjj-;feet contour line1 it is indicated in the map attached to this work4 ,its general level varies between #cjj and #fjj feet in elevation2 but a number of isolated peaks are included within this area4 ,more than one of these hills attain a height of #a1jjj feet1 ,nakambuta a very conspicuous hill being as much as #a1ejj feet4 ,basaltic andesites with basic agglomerates and palagonite-tuffs prevail4 ,towards ,natua the basaltic andesites1 which are often much decomposed1 are of the doleritic type referred to in the account of the ,ndreketi ,plains on page #acc4 ,inland1 towards ,narengali and ,va-lili1 these rocks are often more or less glassy and take the form of pitchstones2 whilst the agglomerates have the same character4 ,the first probably represent submarine flows of basaltic lava which have spread far and wide over the ,ndreketi plains4 ,the inland rocks are1 as is pointed out below1 the products of vents that1 as in the case no doubt of ,mount ,nakambuta1 rose out of a shallow sea4 ,the palagonite-tuffs and clays1 often foraminiferous1 which cover the ,ndreketi plains1 are extensively represented in the lower levels up to #djj feet or more4 ,between one and two miles to the westward of the ,narengali valley1 and immediately north of ,va-lili1 the agglomerates1 overlying palagonite-tuffs1 form lofty precipices4 ,the agglomerates are composed of blocks of more or less vitreous basaltic-andesites1 some of them semi-vitreous and amygdaloidal1 some in the form of pitchstone1 and others again as tachylyte that fuses in the lamp-flame4 ,the underlying palagonite-tuffs are bedded1 and are composed of fragments of basic glass that originally inclosed porphyritic crystals of plagioclase4 ,in the slide it is observed that the glass and mineral fragments have often been re-fractured as they lie in the tuff and that the former have rounded angles and eroded edges4 ,the interstices are filled with a more or less palagonitised magma4 ,similar rocks occur in other localities1 and they will all be found described on page #ccd4 ,it may1 however1 be remarked here that in all cases these rocks would seem to have undergone some crushing1 the heat developed in the process being sufficient to partially remelt the glass4 ,a high temperature was not required to effect this fusion1 since splinters of the tachylyte occurring in the overlying agglomerate fuse in an ordinary lamp-flame4 ,it is pointed out on page #cda that tuffs of this character differ in origin and in characters from the prevailing foraminiferous palagonite-tuffs4 ,the road from ,narengali to ,natua traverses the length of this district4 ,at and near the mouth of the ,narengali valley there are exposed basic tuffs and agglomerates1 the blocks in the last case being formed of a semi-vitreous1 vesicular or almost scoriaceous basaltic andesite4 ,in this neighbourhood the track passes across the top of a waterfall which is the result of the existence of a huge dyke-like mass of a compact basaltic andesite showing a little interstitial glass and referred to genus #ac of the augite-andesites4 ,it lies in a district of tuffs and agglomerates4 ,farther on1 about two miles north-west of ,narengali1 the track crosses some rounded hills1 elevated about #fjj feet1 on the top of which is displayed a concretionary pitchstone1 showing little nodular concretions of the size of filberts1 and having the microscopical characters of 8variolite10 as described on page #cac4 ,this is the only locality of this rock that is known to me4 ,my acquaintance with the tract of ,nakambuta is1 however1 very imperfect4 ,but it is apparent that in the pitchstones and in the semi-vitreous basic rocks1 sometimes vesicular and amygdaloidal1 we get a nearer approach to the products of subaerial eruptions than is to be observed in most other portions of the island4 ,the examination of the ,nakambuta peak by some future investigator will bring to light some interesting facts concerning this region4 ,it is not unlikely that during a late stage of the emergence of this region ,nakambuta and the other peaks around protruded as active vents above the surface of a shallow sea1 at the bottom of which the products of their eruptions accumulated4 ,,the ,,valley ,,of ,,the ,,ndreke-,,ni-,,wai ,,and ,,its ,,tributaries ,ndreke-ni-wai1 which signifies 8the hollow of the water10 is the name of a broad tidal estuary1 opening into ,savu-savu ,bay1 which is formed by the union1 about half a mile above its mouth1 of two rivers1 the ,mbale-mbale ,river flowing from the north-west past a village of that name1 and the ,vatu-kawa ,river1 the largest1 flowing from the eastward1 which ,i have also named after a village on its banks4 ,the valleys of these two rivers are separated by a mountainous dividing-ridge connected by a saddle with the main range4 ,its highest peaks rise to #b1ajj feet above the sea1 the elevation of this 8divide0 rapidly decreasing as it approaches the coast1 where1 within a mile of the beach1 it terminates in some low hills #bjj or #cjj feet in height4 ,it may be observed here that a mouth of the river was originally situated #gjj or #hjj yards to the west of its present site4 ,this old mouth is now represented by a lagoon communicating with the ,mbale-mbale ,river above1 but closed by the sand-mound of the beach at its lower end1 which1 however1 is occasionally broken through when the rivers are in flood4 ,this lagoon is shown in the view facing page #aec4 ,the valley of the ,mbale-mbale ,river1 which is much the smaller of the two rivers1 is bounded on the north by the precipitous slopes of the ,koro-tini ,range1 which rise to over #b1jjj feet1 and on the south and west by the lofty ,va-lili ,range4 ,the valley1 above the village of ,mbale-mbale1 is broad and low-lying2 and one can ascend it to the vicinity of ,waisali1 three to four miles from the river's mouth1 without attaining an elevation of #ajj feet above the sea4 ,the main stream1 which flows down from ,waisali1 is joined near ,mbale-mbale by a more impetuous stream that descends the steep mountain-sides just to the east of the ,koro-tini ,bluff4 ,the valley of the ,vatu-kawa ,river is bounded by lofty mountain-ranges that rise to elevations varying from #b1jjj to #c1ejj feet4 ,on the south side lies the ,mariko ,range1 on the east lies ,mount ,mbatini1 the most elevated peak of the island1 whilst on the north rise up the steep slopes of the ,koro-tini ,range and of the mountainous 8divide40 ,the valley has such a gentle gradient that one can follow it inland for five or six miles from the estuary to the vicinity of ,nukumbolo without exceeding an elevation of #ajj feet above the sea4 ,below ,na ,salia the valley is confined between the hills that approach the river2 but above that village it is very broad2 and on account of its slight fall the river here often changes its course1 so that the floor of the valley is strewn with water-worn blocks and pebbles marking the old channels4 ,the ,vatu-kawa ,river1 which rises on the west slopes of ,mbatini1 flows with a placid current past ,nukumbolo and ,na ,salia1 until it reaches the village of ,vatu-kawa1 where it is joined by its impetuous tributary1 the ,wai-ni-ngio1 8the river of the shark40 ,this affluent1 after descending the steep slopes of the ,koro-tini mountains1 bursts through the dividing range that separates the ,mbale-mbale and the ,vatu-kawa valleys4 ,it would seem that the ,wai-ni-ngio without any great effort on its part might become a tributary of the ,mbale-mbale ,river4 ,the great character of these two valleys1 as shown above1 is their little elevation above the sea4 ,for miles inland the level does not attain #ajj feet1 and high ranges rise steeply in each case on either side to #b1jjj feet and over4 ,here1 as in the instance of most of the large valleys of the island1 the original configuration of the surface was not dependent on river-erosion4 ,rivers no doubt have done much to carve out the lesser and to deepen and widen the greater valleys2 but1 as is often remarked in this work1 the main features of the surface were in existence before the emergence of the island from the sea4 ,the geological formation of the slopes of these two valleys is described in the accounts of the various ascents of the mountains bounding them4 ,since foraminiferous tuffs occur high up their sides1 up to elevations of #b1jjj feet and over1 the valleys themselves were at one time no doubt also covered with these submarine deposits1 which1 however1 have been in great part stripped off by the denuding agencies4 ,they are still to be found1 containing large tests of foraminifera1 between ,mbale-mbale and ,waisali2 but the basaltic andesites1 originally underlying them1 are more frequently exposed4 ,one of these rocks found a little east of ,waisali1 which has an aphanitic appearance and a specific gravity of #bhb1 is merely a basic glass in its early stage of crystallisation1 being made up of very minute crystallites #a_/ejjj of an inch in length4 ,on the surface in this locality there also occur basic agglomerates containing scoriaceous rocks1 the products of some of the last stages of volcanic action in this part of the island4444 ,in the case of the broad part of the ,vatu-kawa valley above ,na ,salia blocks of basic rocks derived from the mountains around strew the bottom in great abundance4 ,lower down1 where the valley is confined between the hills1 basic agglomerates and coarse tuffs are displayed in the hill-sides4 ,mention should be made here of the various hot springs existing in these valleys in the low levels near the rivers and stream-courses4 ,in the ,vatu-kawa valley they exist at ,nukumbolo1 and in the ,mbale-mbale valley at ,natoarau1 ,waitunutunu and other localities4 ,these springs are described in ,chapter ,,iii4 ,illustration3 ,,duniua ,,lagoon1 representing an old mouth of the ,ndreke-ni-wai4 ,behind rises the ,korotini ,tableland 7#b1jjj-c1jjj feet74 ,the cliff-like declivity over the head of the lagoon is the ,korotini ,bluff4 ,,chapter ,,xi ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,koro-,,tini ,,range ,,or ,,table-,,land ,,the level-topped range that forms the mountainous backbone of the island for a distance of nearly #aj miles is one of the remarkable features of ,vanua ,levu4#ff ,in the general profile of the island it is named the ,koro-tini ,table-land on account of the level profile which it presents whether viewed from the north or from the south4 ,but this is merely its appearance en masse4 ,when it is examined in detail it is found that although much of the range has an elevation between #b1jjj and #b1djj feet above the sea1 it attains an elevation of about #c1jjj feet in the case of two gently sloping peaks4 ,with regard also to its table-top1 it is necessary to remark that whilst in some portions of the range the summit is broad and level1 in others it is much cut up into ridges1 and in others again it presents a single narrow crest4 ,nor can we realise on looking at the profile the extent to which its slopes have been carved out by river-erosion1 and we get no indication of the several lofty spurs that descend north and south far into the plains1 as in the case of the spur west of ,sueni and in that terminating in the ,koro-tini ,bluff4 ,in the profile the eye ignores the details with which the investigator during many toilsome ascents has filled the pages of his note-books4 ,to this extent it is useful in that it enables him to rise a little above the level of his facts1 and permits him 7to employ a figure-of-speech7 to regard the style and general character of the edifice without being exclusively absorbed in the study of the bricks4 ,this range1 which extends from a mile or two west of ,sealevu to a couple of miles east of ,sueni1 is connected on the west with the ,va-lili ,range by the ,waisali ,saddle before described1 and on the east with the ,thambeyu or ,mount ,thurston ,range by a broken chain of mountains1 of which ,koro-mbasanga is the most conspicuous4 ,it is connected by an elevated col with ,mount ,mbatini and the ,mariko ,range to the southward4 ,the name of ,koro-tini has been applied to this range because it is familiar to the natives4 ,it signifies 8ten towns10 and was given to a once populous district on the slopes of the lofty bluff overlooking on the north the mouth of the ,ndreke-ni-wai4 ,i crossed the range in four places1 namely1 between ,waisali and ,sealevu1 between ,mbale-mbale and ,vandrani1 between ,vatu-kawa and ,vandrani1 and between ,nukumbolo and ,sueni4 7#a7 ,,traverse ,,of ,,the ,,koro-,,tini ,,range ,,from ,,waisali ,,to ,,sealevu4--,starting from ,waisali by the ,narengali track1 ,i ascended the east slope of the ,waisali ,saddle1 as described on page #adf1 until an elevation of about #gej feet was reached1 when my way lay to the northward across the ,koro-tini ,range to ,sealevu4 ,at #hej feet a singular altered tuff was displayed in position in a stream-course4 ,it shows calcite and pyrites1 and is interesting from the fact that although it is made up largely of basic glass the tuff does not seem to have undergone the palagonitic change4 ,afterwards1 there was a fairly steep ascent to the summit of the range1 #b1djj feet above the sea1 which has merely a ridge-like crest4 ,between an elevation of #a1djj feet and the top there are exposed at the surface compacted coarse and fine palagonite-tuffs and agglomerate-tuffs formed of the same materials4 ,they contain often abundant organic remains1 such as valves of 8,cardium0 and 8,pecten0 shells1 macroscopic tests of ,foraminifera1 and some curious scale-like bodies1 showing a concentric structure and about an inch across1 which look like fish-scales4 ,it is probable that these interesting rocks extend to a greater elevation than #b1djj feet1 which was merely the highest level reached in the traverse1 but is not the highest point of the range4 ,these deposits are made up in mass of a more or less palagonitised basic glass originally containing phenocrysts of plagioclase and pyroxene4 ,the palagonitic process is nearly always far advanced2 but it is seen in all its stages1 the least altered materials fusing under the blow-pipe into a black glass4 ,the fragments are usually sub-angular in the case of the coarse tuffs2 but small rounded pebbles up to half an inch in size and fine water-worn gravel are not infrequent4 ,the matrix is composed of palagonitic debris1 portions of crystals of plagioclase and pyroxene1 fine gravel1 occasional tests of foraminifera2 and it often contains a fair amount of carbonate of lime1 in one specimen tested as much as #ac per cent4 ,the amount of lime1 however1 varies1 being in some places scanty4 ,the term 8conglomerate0 could not be applied to the coarser deposits1 since the sub-angular and angular fragments always predominate4 ,they could scarcely be deemed 8breccias0 on account of the mixture with pebbles and gravel4 ,their character is therefore intermediate between the two4 ,i have used the expression 8agglomerate-tuff0 because it best describes their appearance4 ,a specimen of such a rock presents a curious mixture1 in the well-compacted mass1 of angular and sub-rounded fragments of palagonite up to an inch in size1 small pebbles and fine gravel of the same material1 and detached valves of 8,cardium10 entire and broken4 ,one is forced to draw the inference that these materials accumulated in shallow water4 ,they are such as might have been produced by the marine erosion of an emerging volcanic island endeavouring to hold its own above the waves4 ,but from the occasional occurrence of blocks of a scoriaceous basaltic rock it would appear that during the formation of the deposits there were periods of eruption4 ,at times massive and comparatively fresh-looking basaltic rocks are exposed in situ on the mountain sides in the midst of these submarine deposits4 ,a specimen obtained at #a1hjj feet is a semi-ophitic porphyritic olivine-basalt with a specific gravity of #bhf and showing a little interstitial glass4 ,the mode of exposure did not admit of my ascertaining the exact relation of these rocks to the deposits4 ,they are no doubt dyke-like masses representing the original fissures of eruption of a submarine vent2 and during the emergence they were covered up with tuffs and deposits1 the work of the marine erosion of the emerging land4 ,these1 however1 are points on which light will be thrown when we come to examine other localities4 ,descending the northern slopes of the range from the summit to ,sealevu the general course was ,n4,n4,e4 ,several valleys were crossed1 of which that occupied by the ,na ,sinu river was #fjj feet in depth1 the rivers and streams all flowing to the north-west into the ,ndreketi basin4 ,basic tuffs and agglomerates were exposed at the surface all the way down to ,sealevu1 #djj feet above the sea4 ,at the head of the ,sealevu valley1 about a mile or rather more above the village1 and a little east of the track followed in the descent above described1 the mountain-range terminates abruptly in lofty cliffs #djj or #ejj feet in height4 ,at their base1 which is about #a1jjj feet above the sea1 once stood the village of ,lovutu4 ,these cliffs are formed of basic agglomerate-tuffs which display a horizontal arrangement1 but there is no distinct bedding4 ,they have the castellated appearance that often characterises horizontally bedded sedimentary formations4 ,the inclosed rock-fragments vary in size from #ah inches to half an inch and smaller4 ,the larger are angular or sub-angular1 and are composed of hemicrystalline basaltic andesites1 scoriaceous and vesicular and sometimes amygdaloidal4 ,the smaller fragments are more or less rounded and of the same material4 ,the matrix is made up of fine detritus of the large fragments and of lapilli of a vacuolar palagonitic basic glass1 whilst small crystals of calcite fill the cavities and line the fissures4 ,the phenocrysts of plagioclase and augite inclosed in the altered glass also display extensive alteration1 and in the first case are largely replaced by calcite1 secondary quartz1 and other products4 ,no organic remains came under my notice2 but on account of the alteration of the tuff-matrix their preservation could hardly be expected4 ,bearing in mind1 however1 the fossiliferous character of the tuffs and agglomerates in the higher part of the range1 it can scarcely be doubted that the agglomerate-tuffs of the ,sealevu cliffs are also submarine4 ,each traverse of the great ,koro-tini ,range will provide us with new facts to aid us in framing an explanation of the origin of this long mountain-ridge4 ,the principal lesson to be learned from the journey across the range from ,waisali to ,sealevu1 and from the visit to the cliffs1 is concerned with the great extent and thickness of these submarine basic tuffs and agglomerates4 ,from #a1jjj feet above the sea up to the summit1 #b1djj feet in height1 they are almost the only rocks exposed1 excepting the occasional masses of basaltic rocks1 which probably represent dykes4 ,their maximum thickness must amount to some hundreds of feet4 7#b7 ,,traverse ,,of ,,the ,,koro-,,tini ,,range ,,from ,,mbale-,,mbale ,,to ,,vandrani4--,in this traverse the track before ascending to the summit crosses a spur of the ,koro-tini ,bluff1 and then descends into the valley of the ,natoarau river on the east side of it4 ,it will therefore be convenient to describe the bluff before giving my description of the journey across the range4 ,the ,koro-tini ,bluff is a lofty headland 7if ,i may so term it71 lying about four miles inland from the mouth of the ,ndreke-ni-wai4 ,it attains an elevation of about #b1jjj feet1 and terminates above in a line of precipices #cjj or #djj feet in height4 ,it represents the southern edge of the level-topped mountain range behind1 and like the ,sealevu cliffs on the north side it affords a natural section of its mass4 ,it is shown in the plate facing page #aec1 where it rises at the back of the lagoon4 ,approaching the bluff from ,mbale-mbale1 one crosses a low-lying district less than #ajj feet above the sea before striking the spur4 ,here and in the lower few hundred feet of the spur are exposed basic agglomerates1 and occasionally in the mass a semi-vitreous vesicular olivine-basalt1 almost like a pitchstone1 and displaying large porphyritic crystals of plagioclase1 #e or #f millimetres long1 the agglomerates being made up of the same material4 ,higher up1 at elevations between #a1jjj and #a1ejj feet1 are exposed coarse palagonite-tuffs made up of fragments1 usually #a to #c mm4 in size1 of extensively palagonitised basic vitreous rocks1 such as occur in the cliffs above4 ,these tuffs become coarser as one approaches the precipitous bluff1 the base of which lies about #a1fej feet above the sea4 ,here the cliffs present a bare rocky face1 some #bjj feet high4 ,the lower portion is composed of an agglomerate-tuff1 and the upper portion mainly of agglomerates4 ,these deposits display no bedding excepting a single plane of division inclined steeply to the north at an angle of perhaps #dj4 ,the blocks in the agglomerate-tuff are either angular or sub-angular1 and are less than a foot across4 ,they are all composed of more or less vitreous porphyritic olivine-basalts1 showing large crystals of plagioclase a fifth of an inch 7#e or #f mm47 in length4 ,but they vary somewhat in character4 ,some of them1 that are vesicular and almost scoriaceous1 may be termed from their glassy nature porphyritic pitchstones4 ,others again1 where the groundmass is hemi-crystalline1 may be designated porphyritic compact basalts1 and are referred to genus #cg of the olivine-basalts4 ,the matrix of the agglomerate-tuff is made up of angular fragments1 up to #e mm4 in size1 of singular vitreous and semi-vitreous olivine-basalts1 in part palagonitised4 ,there is evidence of crushing in situ of some of the porphyritic felspar crystals2 but it is not so marked as elsewhere noticed4 ,the palagonite is also in part interstitial1 a character that goes to support the view advanced on page #cdb1 that the palagonite may be connected in its origin with the heat developed during crushing1 only a moderate temperature being required for the partial fusion of the glass4 ,in crossing the range by this route from ,mbale-mbale one first ascends1 as above observed1 the spur of the ,koro-tini ,bluff up to a height of #a1bjj feet4 ,the track then descends into the valley-gorge of the ,natoarau river on the east1 the bottom of which is #gej feet above the sea1 and from here the climb begins4 ,one ascends the bed of the stream course1 clambering over slippery rock surfaces up to #a1bjj or #a1cjj feet1 where the stream is left1 and the mountain-slopes1 often steep and precipitous1 are then followed to the summit1 #b1jjj feet in height4 ,coarse and fine palagonite-tuffs and agglomerate-tuffs of the same character are exposed on the surface from the commencement of the ascent up to #a1hej feet2 but they are displayed much more extensively in the stream-course than in the soil-covered upper slopes4 ,the tuffs are grey except when hydrated1 when they turn yellowish-brown4 ,some of them contain lime1 as much at times as #aj or #ab per cent42 whilst others possess little or none4 ,tests of foraminifera are not infrequently inclosed1 even as high as #a1hej feet4 ,a description of one of these tuffs containing a few tests of ,globigerina1 which was obtained at #a1bjj feet1 is given on page #cca1 under sample ,d4 ,it will be there seen that they are derived from different basic rocks1 some containing but little glass1 others mainly vitreous1 only the more glassy constituents being palagonitised4 ,the palagonite-tuff sandstones exposed in large blocks on a bare spur at #a1hej feet contain #ab per cent4 of lime1 the largest tests of foraminifera being not over half a millimetre4#fg ,these tuffs occasionally show bedding4 ,at #a1jjj feet they dip gently to the ,s4,s4,w41 and at #gej feet they are inclined about #ae in the same direction4 ,in this last locality they consist of alternating layers1 #a to #d inches in thickness1 of fine and coarse tuffs1 the coarser looking like sandstone4444 ,the blocks in the agglomerate-tuff are sub-angular1 and of an olivine-basalt with hemi-crystalline groundmass1#fh their size ranging from #b feet to an inch4 ,i noticed one large block of this rock1 measuring #b #a #a feet1 imbedded alone in the tuffs at #a1bjj feet4 ,at one place a tuff containing small fragments of basalt displayed a concretionary structure1 indicating probably the proximity of a dyke1 the globular masses being #d feet across4 ,a little lime occurs in the matrix of the agglomerate-tuff4 ,the summit of the range1 #b1jjj feet in height1 is 8ridgy10 about half a mile in width1 and cannot therefore be described as table-topped4 ,the rocks exposed in blocks on the surface are composed of a semi-ophitic olivine-basalt containing a large amount of interstitial glass which shows the fibrous crystallites of the early stage devitrification4 ,it is referred to genus #cc of the olivine-basalts4 ,descending the northern side of the range ,i followed the steep slopes down to #a1jjj feet above the sea4 ,a rubbly doleritic olivine-basalt1 semi-ophitic1 and assigned to the same genus 7#cc71 prevailed on the way2 and it is probable that a waterfall with a drop of #ej feet or more that is situated on these slopes indicates a large intrusive mass of this rock4 ,during the rest of the descent to ,vandrani1 which lies in a valley at the foot of the range1 and is elevated about #cjj feet above the sea1 basic agglomerates and palagonite-tuffs1 together with deposits intermediate in character1 were exposed at the surface4 ,at times a semi-ophitic doleritic basalt similar to those displayed above1 but without olivine1 occurred in position4 ,the blocks in the agglomerates are formed of a compact semi-vitreous basaltic rock1 and are sometimes vesicular4 ,at one place the palagonite-tuffs exhibited signs of alteration1 being traversed by small fissures not over a third of an inch broad 7#e to #h mm471 and filled with a zeolite behaving like natrolite4 ,in some cliffs by the river at ,vandrani are displayed fine and coarse non-calcareous palagonite-tuffs1 bedded and dipping about #ae ,n4 by ,w4 ,they are penetrated by cracks1 #e mm4 in breadth1 which are filled with chalcedony4 ,these tuffs are evidently in part derived from acid as well as from basic rocks1 though mainly from the latter2 and they show other alteration-characters4 ,at the mouth of the ,vandrani valley there are exposed in the river-bed coarse palagonite-tuff sandstones containing a little lime1 and probably a few tests of foraminifera4 ,reference may here be made to the mountain of ,ravi-koro which1 when seen from the north-east1 rises up as a partially independent peak1 with a broad base and a conical truncated summit1 immediately west of the track followed in the descent from the summit of the range to ,vandrani4 ,it is probably not much under #b1jjj feet in height1 and exhibits bare precipitous cliff-faces on the north side4 ,it would be worthy of the attention of the future investigator4 ,recurring to the principal features of the range between ,mbale-mbale and ,vandrani1 one may remark the extensive occurrence of basic agglomerates and tuffs on both slopes1 the prevalence of olivine-basalts1 the frequency of the semi-vitreous and vitreous or rather pitchstone condition of these rocks1 and their semi-ophitic character1 especially on the summit and north slopes4 ,from the vesicular structure of the rocks of the ,koro-tini ,bluff and from the character of its tuffs and agglomerates1 it is to be inferred that they are the direct products of eruptions1 probably in shallow seas4 ,on the other hand1 the tuffs 7often foraminiferous7 as well as the agglomerate-tuffs of the north and south slopes of the range are in part suggestive of marine erosion4 ,intrusive masses of basalt are to be observed occasionally1 and doubtless to this cause may be attributed the concretionary structure of the tuffs in places1 and the alteration of these deposits in one or two localities1 where they are penetrated by cracks filled with chalcedony4 7#c7 ,,traverse ,,of ,,the ,,koro-,,tini ,,range ,,from ,,vatu-,,kawa ,,to ,,vandrani4--,on leaving ,vatu-kawa#fi1 which is not more than #ej feet above the sea1 the ascent for the first #fjj feet up the steep mountain-side lies along the rocky bed of the ,wai-ni-ngio ,river1 which from its rapid fall has more the character of a torrent4 ,on its sides are exposed basic agglomerates and agglomerate-tuffs2 whilst the large boulders in its bed are composed of a somewhat altered olivine-basalt4 ,at #fjj feet the track abandons the stream-course for the steep mountain slopes1 and thence up to #a1ajj feet similar agglomerates and tuffs prevail4 ,at this last-named elevation there are displayed fine and coarse indurated palagonite-tuffs1 a little altered in character and with little or no lime4 ,a specimen of the former1 of which the materials composing it do not exceed #b mm4 in size1 shows in the slide an occasional 8,globigerina0 test filled with palagonitic debris4 ,such a marine deposit is evidently not of shallow-water origin4 ,the coarser tuff is made up of compacted sub-angular fragments1 not over #b mm4 in size2 but contains no organic remains4 ,the prevailing rocks exposed between #a1ajj and #a1ijj feet1 a little below the summit of the range1 are somewhat altered compacted non-calcareous breccia-tuffs1 composed of sub-angular fragments #e or #f mm4 in size1 of a more or less glassy and often vacuolar basic or basaltic andesite1 only in part palagonitised1 the vacuoles as well as the interstices between the fragments being sometimes filled with a zeolite4#gj ,the summit of the range may be described as a 8ridgy0 table-land4 ,though about #b miles in breadth1 its level only varies between #b1jjj and #b1bjj feet1 the inequalities being probably the effect of denudation4 ,here1 as in many other similar localities1 on account of the dense forest it was only possible to determine the surface-configuration by the use of compass1 watch and aneroid4 ,the prevailing rocks displayed in this region are grey non-calcareous basic tuffs1 somewhat altered in character1 and composed of fragments usually not exceeding #a mm4 in size of a basic glass1 the palagonitic process being masked by other changes4 ,these tuffs often become brownish-yellow through hydration4 ,tests of foraminifera are enclosed1 but they are very scanty4 ,on the north slopes basic agglomerates and palagonite-tuffs are the predominant rocks down to the foot of the range4 ,a specimen of the tuffs taken at #a1cjj feet is calcareous in patches and probably contains tests of foraminifera2 but it is too much weathered to enable one to speak with certainty on this point4 ,the interesting feature of this slope is the exposure at #a1fjj to #a1gjj feet of large blocks of a dark grey hypersthene-augite andesite referred to the orthophyric order of those rocks described on page #bij4 ,lower down 7#a1jjj-a1cjj feet7 occasional solitary blocks of the same rock1 but somewhat altered1 occur imbedded in the palagonite-tuff4 ,this type of rock which is characterised by the orthophyric structure of the groundmass and by other features is rarely represented in ,vanua ,levu4 ,summing up the general results of this traverse we observe that here1 as in other parts of the range1 basic agglomerates1 breccias1 and tuffs1 the last however scantily foraminiferous1 occupy a great extent of the slopes and summit4 ,the alteration of these deposits on the southern slopes is noteworthy4 ,the only deeper seated massive rocks observed were the pyroxene-andesites above alluded to4 7#d7 ,,traverse ,,of ,,the ,,koro-,,tini ,,range ,,from ,,nukumbolo ,,to ,,sueni4--,the hot springs at ,nukumbolo1 which are described on page #bd1 rise up through agglomerate-tuffs4 ,around the bathing pools lie large masses of altered palagonite-tuffs which give the first indication of the region of altered rocks that extends from ,nukumbolo to the lower slopes of the range1 a distance of about three miles4 ,for about a mile and a half or two miles from this place the track lies through a broken country and does not rise to a height more than #cjj feet above the sea4 ,a variety of altered rocks are here exposed in position in the stream courses4 ,some of them are fine and coarse basic tuffs showing secondary calcite1 quartz and opal1 as alteration products4 ,others are palagonite-breccias with the vacuoles of the altered glass filled with opal4 ,others again are massive basic rocks1 such as fine-textured augite-andesites1 or doleritic basaltic andesites1 semi-ophitic in character1 the plagioclase phenocrysts being more or less occupied by calcitic and other products4 ,the alteration is not always far advanced1 but it is sufficiently marked to give a common character to the rocks of the district4 ,ascending the lower slopes of the range up to #hjj feet one finds the altered rocks still exposed in the stream-courses2 but the changes exhibited are not always the same4 ,a specimen from #ejj feet looks like a tuff1 but in the slide it appears as a semi-vitreous augite-andesite1 its substance being penetrated by fine veins of chalcedonic quartz and opal1 whilst the same material is developed within the larger plagioclase crystals4 ,another specimen from #hjj feet1 which is apparently a tuff1 contains so much lime that it effervesces freely with an acid4 ,it was composed originally of fragments of a hemi-crystalline basic rock1 of which the plagioclase phenocrysts have been replaced by calcite2 whilst the augite and interstitial glass is now represented by viridite and a chloritic mineral4 ,it is to be inferred that at some time hot springs were very numerous in the district between ,nukumbolo and the lower slopes of the range1 those at ,nukumbolo1 as far as ,i know1 alone existing in our time4 ,from a height of #a1ajj or #a1bjj feet the mountain slopes rise steeply to the summit rather over #b1jjj feet in elevation4 ,at the foot are exposed in situ aphanitic augite-andesites1#ga which in some specimens show a little alteration in the chalcedonic quartz filling minute cracks1 and in one case there is an irregular cavity1 inch across1 filled with milk-white opal4 ,another rock exposed at the foot of the steep ascent is a semi-vitreous basaltic-andesite1 doleritic in texture and ophitic structure1 but apparently not much changed4#gb ,at #a1gjj feet is displayed a vesicular basic andesite1 semi-vitreous in character1 and above this ,i found a porphyritic basaltic andesite4 ,the summit of the range is #a or #b miles in breadth and is relatively level1 its undulating surface varying in elevation between #a1ijj and #b1bjj feet4 ,the prevailing rocks exposed on this elevated plateau are vitreous pitchstone-like rocks finely vesicular and scoriaceous1 the cavities being filled either with aragonite or with opal4 ,the basic glass1 of which they are formed1 shows incipient crystals1 and begins to fuse in an ordinary flame4 ,one specimen obtained here is a doleritic basaltic andesite1 slightly ophitic and containing a fair amount of residual glass4#gc ,however1 the vitreous and scoriaceous character of most of the rocks on the summit is very remarkable4 7,similar rocks occur on the top of ,mount ,thambeyu where the slopes of the mountain are covered with submarine tuffs and agglomerates47 ,there is a precipitous descent on the north side of the range to ,sueni at its foot1 massive basaltic andesites being exposed at first1 whilst basic tuffs and agglomerates are displayed lower down4 ,the special features of this traverse of the range are the alteration of the tuffs and massive rocks between ,nukumbolo and the lower southern slopes1 the variation in character of the basic rocks in the upper southern slopes1 the occurrence of vitreous vesicular and scoriaceous rocks on the summit1 and the restriction of the ordinary basic agglomerates and tuffs to the northern slopes4 ,any attempt on my part to explain the structure of this part of the range from the data here given would be futile without comparing them with those obtained from other parts of the range4 ,it will be subsequently pointed out that the difficulties will be in part removed if it is assumed that the submarine palagonite-tuffs and agglomerates1 that so often cover the flanks of the mountains to their summits1 have been in this case largely stripped off by the denuding agencies4 7#e7 ,,the ,,sueni ,,valley4--,my acquaintance with the extreme eastern part of the ,koro-tini ,range is restricted to the descent of the picturesque valley from ,sueni to ,koro-utari4 ,it is occupied by a tributary of the ,lambasa ,river1 and is bounded on the east side by the lofty slopes of the main range1 and to the westward by a mountainous spur that projects far into the ,lambasa plains4 ,sueni lies by the river-side in the midst of mountains which rise steeply on most sides to heights of #b1jjj feet and over1 and often display precipitous bare faces apparently of volcanic agglomerates4 ,numerous waterfalls may be observed on their flanks1 which1 as in other localities1 doubtless indicate the occurrence of large intrusive dykes4 ,sueni is situated about #cjj feet above the sea1 the descent to ,koro-utari at the mouth of the valley1 a distance of #c to #d miles in a direct line1 being about #aej feet4 ,the river as it flows down the valley from ,sueni to ,koro-utari traverses a region of basic agglomerates and agglomerate-tuffs4 ,these deposits1 as they are displayed in the hill-slopes lying ,w4,s4,w4 and at the back of ,sueni1 are composed of blocks of the size of the fist of a vesicular basaltic andesite2 whilst the large masses on the surface are made of the same1 but non-vesicular1 rock4 ,the blocks in the agglomerates between ,sueni and ,koro-utari range usually from a few inches to a foot in diameter4 ,a specimen obtained from one of them is made of a partly vitreous basaltic andesite2 whilst in another case the rock is an altered basic andesite1 the glassy groundmass being largely impregnated with colloid silica looking like opal under the lens4#gd ,nearly a mile below ,sueni1 within a space of less than #fj yards1 there are exposed at the river-side in the agglomerates three vertical or nearly vertical dykes1 #d to #f feet in thickness4 ,they trend roughly ,n4,e4 and ,s4,w41 and are non-columnar1 except in the case of the one farthest up the river1 which has rude1 transverse joints4#ge ,the rocks composing these dykes are somewhat doleritic basaltic andesites1 olivine being very rare or absent4 ,the two highest1 which are only #ae to #bj feet apart1 are made of similar rocks characterised by abundant interstitial glass1 and having a sp4 gr4 of #bgh4 ,the rock of the third dyke1 about #ej yards farther down the river1 has but scanty glass in the groundmass1 the sp4 gr4 being #bhi4 ,the differences between the two types represented in the three dykes are mainly concerned with the degree of crystallisation1 and it is probable that though not contemporaneous they were derived from the same fluid magma which1 as we may infer from the proximity and lie of the dykes1 was situated at no great depth4#gf ,,general ,,inference ,,respecting ,,the ,,koro-,,tini ,,range4--,if we can imagine a line of vents1 protruding in some cases above the surface of the sea1 that were ultimately worn down to a common level through marine-erosion1 and were then largely covered over with submarine tuffs and agglomerates1 we should have in our mind's eye the first and most important stage in the formation of this range4 ,if we then assume that there followed a period of emergence characterised by a renewal on a very extensive scale of marine-erosion1 during which the agglomerates were mainly formed1 and that since that period the sub-aerial denuding agencies have been for ages in operation1 we shall1 ,i think1 obtain some idea of the history of the ,koro-tini ,range4 ,,chapter ,,xii ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,koro-,,mbasanga ,,range ,,as is illustrated in the accompanying profile-sketch1 the relatively level-topped range of ,koro-tini gives place at its eastern end to a broken line of mountains1 of which the round-topped ,koro-tambu1 #b1gec feet in height1 and the pinnacled ,koro-mbasanga1#gg #b1ecg feet1 are the highest peaks4 ,further east lies the broad ,vuinandi ,gap which separates the ,koro-mbasanga and ,mount ,thurston1 or ,thambeyu1 ranges4 ,the twin-peaks of ,mount ,mbatini1 the highest mountain of the island1 appear in the background in the sketch1 and to the left rises ,thambeyu1 the second highest summit4 ,we enter here another complex region of mountains2 and if the character of the rocks are sometimes different we shall yet have to bear in mind in our interpretation of its geological features the lesson derived from the examination of the ,koro-tini ,range4 ,before and behind all our facts of observation lie the two great periods of marine-erosion and the later ages of sub-aerial denudation4 ,when approached from the north1 the western part of the range has a rude crescentic form1 and looks like the remnant of a gigantic crater-cavity about two miles across4 ,at the back rise1 as shown in the second of the profile-sketches1 the precipitous slopes of ,koro-mbasanga proper2 whilst the two spurs descending from it1 one on the west1 the ,sokena spur1 towards ,koro-utari1 the other on the east1 at the back of ,nasawana1 give the crescentic figure open to the north4 ,the last-named village lies nestled in this great hollow1 the floor of which1 though not in its lowest part below the level of the ,lambasa plains1 is not over #bjj feet above the sea4 ,however1 the facts adduced in the following description of this region do not give much support to this view of its surface-configuration4 ,for the convenience of description1 ,i will first describe the peak of ,koro-mbasanga1 and then the ,sokena ridge and1 lastly1 the ,lovo valley that cuts through the range to the eastward4 ,illustration3 ,these three sections form a continuous profile-sketch of the mountainous axis of ,vanua ,levu for a length of #ae or #af miles and include the ,thambeyu1 ,koro-mbasanga1 and ,koro-tini ranges as viewed from the northward near ,na ,kama4 ,the eastern section is at the top and the western section at the bottom4 ,the summit of ,thambeyu was covered with clouds4 ,illustration3 ,koro-mbasanga from the north-north-east4 7#a7 ,,koro-,,mbasanga4--,the ascent of ,koro-mbasanga is best made from ,nasawana1 a village at its base1 elevated rather over #bjj feet above the sea1 and distant about a mile and a half north-east from the peak4 ,on the way to the foot of the mountain we traverse an undulating region of basaltic andesite1#gh which is merely the extension to the base of the mountains of the basaltic ,lambasa plains4 ,after commencing the ascent of the steep slopes1 we find exposed in a stream-course1 #gjj to #hjj feet above the sea1 a sedimentary basic tuff1 presenting layers of coarse and fine materials1 and partly palagonitic in composition4 ,it is a little calcareous1 and apparently incloses tests of foraminifera4 ,these submarine deposits have evidently been stripped off the basaltic low-lands beneath4 ,it thus becomes evident that the structural features of the ,lambasa plains 7basaltic rocks overlain by submarine deposits7 are preserved to the base of the range4 ,these submarine deposits1 as exposed in the stream-course1 lie beneath agglomerates which repose horizontally upon them2 and from this level up to the bare rocky peak of the mountain1 agglomerates and agglomerate-tuffs are alone displayed either as large detached masses or in cliff-faces4 ,in the lower part of the mountain the blocks1 usually sub-angular1 are about a foot across2 but they become smaller as one ascends towards the summit1 where they are #c or #d inches in diameter4 ,at the top there are extensive exposures in cliff-faces of the agglomerate-tuffs2 and here the finer materials of the matrix include a few rounded pebbles not exceeding half an inch in size4 ,this is a fact of importance in connection with the submarine origin of these formations4 ,as regards their composition1 the blocks of the agglomerates have not the uniform character we would expect to find in the case of materials directly ejected from a volcanic vent4 ,the most frequent type of rock represented is a grey hypersthene-augite-andesite1 having a specific gravity of #bgb-bgh4 ,it displays small phenocrysts of plagioclase and of rhombic and monoclinic pyroxene1 but in other respects it exhibits much variety1 not only in the arrangement and average length of the felspar-lathes 7#jh to #ah mm47 but in the form of the pyroxene of the groundmass 7either granular or prismatic7 and in the amount of residual glass1 sometimes abundant1 sometimes scanty4 ,two distinct genera 7#a and #e7 of the sub-class are therefore represented4 ,other rocks found in these agglomerates contain no rhombic pyroxene1 and are referred to genera #ac and #af of the augite-andesites according to the presence or absence of plagioclase phenocrysts4 ,in the last case we have a dark aphanitic rock 7sp4 gr4 #bgd71 sometimes scoriaceous1 where the average length of the felspar-lathes may be as little as #jd mm4 ,one of the blocks was composed of a highly scoriaceous semi-vitreous rock1 the cavities being filled with a zeolite4 ,another was composed of a black porphyritic augite-andesite1 showing large crystals of plagioclase4444 ,the matrix of the agglomerate-tuff is formed of sub-angular and rounded fragments1 up to a centimetre in size1 of the same andesites1 the interstitial material being formed of fine detritus and palagonitic debris4 ,though the agglomerates of the peak of ,koro-mbasanga are composed of a variety of rocks1 all the rocks are to be referred to the pyroxene-andesites with specific gravity below #bh but above #bg4 ,they are therefore less basic than the olivine-basalts and basaltic andesites of the ,koro-tini range1 where the density is usually #bh and over4 ,their variation1 however1 is more consistent with the characters of an agglomerate formed by marine erosion4 ,the same may be said of the sorting of the blocks according to their size and of the occasional occurrence in the matrix of small rounded pebbles4 ,that these deposits of agglomerates were formed under the sea is indicated also by their overlying submarine sedimentary tuffs near the base of the mountain4 7#b7 ,,the ,,sokena ,,ridge4--,to the west of ,koro-mbasanga1 and forming a spur of the same range1 is the flat-topped hill of ,sokena1 which rises about #a1ajj feet above the country at its base and about #a1fjj feet above the sea4 ,from a distance it has the appearance of being formed in its higher portion of nearly horizontal strata dipping gently northward4 ,in its upper part it terminates in a line of cliffs about #bjj feet in height1 and there is a similar line of cliffs lower down the slopes4 ,these cliffs are composed of bedded fine and coarse non-calcareous tuffs1 dipping about #aj ,n4,n4,w41 in which are imbedded without any arrangement blocks1 ranging in size from #b or #c inches to #c or #d feet1 of a remarkable blackish pitchstone-like rock displaying opaque plagioclase phenocrysts4 ,it is referred to genus #ah 7see page #bhi7 of the hypersthene-augite andesites1 both rhombic and monoclinic pyroxene being represented in the phenocrysts and in the groundmass where they take the form of minute prisms 7#jc mm474 ,there is a considerable amount of pale brown glass4 ,a rock very similar occurs in the ,thambeyu agglomerates 7see page #agh74 ,the tuffs are formed largely of palagonitic materials1 the angular fragments in the coarser beds being to #b centimetres in size1 the palagonite being often vacuolar but much affected by hydration4 ,these tuffs and agglomerates of the ,sokena cliffs apparently contain no organic remains4 ,they appear to have accumulated under water as the result of the eruptions of a neighbouring vent without the intermediate agency of marine erosion4 7#c7 ,,the ,,ascent ,,of ,,the ,,lovo ,,valley4--,about two miles to the east of the peak of ,koro-mbasanga the picturesque ,lovo valley cuts deeply in a southerly direction into the mountainous backbone of the island4 ,the site of the old town of ,lovo lies within the valley about two miles from its mouth4 8,lovo0 is the ,fijian word for a cannibal-oven2 and ,i gathered from my natives that in the old times this vale was noted for its cannibal orgies4 ,it is occupied by the ,nasawana tributary of the ,lambasa ,river1 and often becomes so narrow that it may be described as a gorge4 ,i followed the valley from its mouth1 where it is elevated about #cjj feet above the sea1 for some miles in a southerly direction up to a height of #a1jjj feet1 where the northern slope of the great mountain-mass of ,mbatini commences4 ,on either side of the ,lovo valley rise precipitous mountain-slopes1 displaying in their cliff-faces and in the large detached rock-masses basic agglomerates4 ,the same formation is also usually displayed in the sides of the river4 ,the blocks composing the agglomerates are formed of the usual type of hemi-crystalline or semi-vitreous blackish basaltic andesite so characteristic of these deposits4 ,it is generally compact1 but is at times amygdaloidal4 ,some distance below the old site of ,lovo1 and at an elevation of about #ejj feet above the sea1 there is an interesting exposure in the river-side1 where the agglomerates overlie bedded coarse calcareous basic tuffs containing large flat tests of foraminifera with pieces of molluscan shells1 and dipping about #ae ,s4,w4 ,these tuffs can be traced up the valley towards ,lovo4 ,displayed in mass in the bed of the river in the same locality1 and beneath the submarine tuff just referred to1 is a porphyritic basaltic andesite 7sp4 gr4 #bgi7 containing but scanty interstitial glass1 the felspar-lathes being #ae mm4 in average length4 ,it is referred to genus #a of the augite-andesites4 ,the same rock is exposed at intervals in the river-bed as far as ,lovo1 which is about #hej feet above the sea4 ,at one place it exhibits a rudely columnar structure1 the columns being horizontal and #b to #b feet in diameter1 the trend of the dyke-like mass being ,w4 by ,s4 and ,e4 by ,n4 ,near ,lovo a small dyke1 #f feet thick and trending ,n4,n4,w4 and ,s4,s4,e41 pierces the agglomerate4 ,it is composed of a somewhat aphanitic augite-andesite closely resembling the rocks exposed in the river-course for a mile or so above ,lovo up to an elevation of #a1jjj feet4 ,in this upper part of the valley whilst agglomerates are exposed in the cliffs and precipitous mountain-slopes on either side1 pyroxene-andesites1 somewhat aphanitic in texture and with a specific gravity of #bfh to #bg1 are displayed in mass in the river bed4 ,these last-named rocks1 which are closely similar to those found on the lower slopes of ,mount ,mbatini 7see page #agc7 are1 as ,i should have also remarked in the case of the basaltic andesite above mentioned1 a little altered1 as is indicated by the existence of calcite and viridite in the groundmass4#gi ,from this instructive ascent of the ,lovo valley we may learn that whilst the mountain mass is formed1 to a considerable depth1 of agglomerates with underlying submarine tuffs1 the deeper seated rocks exposed in the river-beds are massive intrusive rocks4 ,the overlying agglomerates have preserved the submarine tuffs from destruction1 and there is no difficulty in assuming that they also were accumulated under the sea1 but in shallow water1 as evidenced by the character of the tuffs4 ,i found no signs of alteration in these tuffs1 and except in the case of the small dyke above noticed there is no sign of the dykes penetrating the agglomerates4 ,we have here a section into the heart of the mountain-range2 and assuming that the large intrusive masses of basic andesites had penetrated these deposits1 there would certainly have been some evidence of this in the extensive exposures of agglomerates far up the mountain-sides4 ,as it is1 however1 we find such rocks only in the deeply excavated river-bed4 ,if we imagine a submarine volcanic mountain1 or one but slightly raised above the surface of the sea1 to be subjected during a long period of emergence to marine erosion1 the 8basal wreck0 of the mountain would ultimately be covered over by submarine tuffs and agglomerates4 ,this is the condition that seems to be presented here4 ,i did not make the ascent of ,koro-tambu1 the other principal peak of the ,koro-mbasanga ,range4 ,this round-topped mountain is well seen from the summit of ,mbatini from which it bears ,n4 #cj ,w4 by compass4 ,it is probably the peak marked #b1gec feet in the ,admiralty chart1 and is connected with ,mbatini by a saddle not under #a1ejj feet in elevation4 ,some of the most important features in the above account of this district may here be emphasised4 ,we have seen that in the peak of ,koro-mbasanga and in the ,lovo valley agglomerates and agglomerate-tuffs1 several hundred feet thick1 overlie sedimentary submarine tuffs4 ,in the last-named locality the deeper massive basic rocks are also exposed2 and we may infer in both instances that the agglomerate-formation is a submarine deposit4 ,on the other hand1 in the ,sokena ,ridge1 which is a spur of the main range1 we have apparently the accumulation of materials on a sea-bottom1 directly ejected from a vent without the intervention of the agency of marine-erosion4 ,in regard to this and other districts in this part of the island it should be remembered that east and west occur undoubted evidences of extensive submergence4 ,it has already been shown that submarine tuffs containing tests of foraminifera and other organic remains occur at heights of #b1jjj feet and over on the summit of the ,koro-tini ,range1 and it will be subsequently shown that similar deposits are to be found on the neighbouring slopes of ,thambeyu as high as #b1ajj feet4 ,,mount ,,mbatini ,according to the ,admiralty chart this is the highest mountain in ,vanua ,levu1 its elevation being #c1dcg feet4 ,it has twin peaks which lie either ,n4,w4 and ,s4,e4 or ,w4,n4,w4 and ,e4,s4,e4 with each other4 ,the northerly or westerly peak is pointed and tooth-like4 ,hence probably arises its name of ,mbatini 7mbati-tooth74 ,the southerly or easterly peak is known as ,soro-levu4 ,it has a broadly conical outline with a truncated summit4 ,the mountain is named ,koro-mbasanga in the ,admiralty chart1 a name that really belongs to a peak lying about #c miles nearly due north 7,n4 #e ,w474 ,the natives are very clear in this matter2 but it must be remarked in this connection that ,koro-mbasanga1 which signifies 8a forked eminence10 would be a very suitable appellation for the double-peaked summit of ,mbatini4#hj ,by the natives of the surrounding district the whole mountain is known as ,mbatini2 but by the natives of the eastern shores of ,natewa ,bay1 it is usually known as ,soro-levu1 since the western peak is often more or less hidden from view or is less conspicuous4 ,the profile of this mountain and of the neighbouring region is shown in the accompanying profile-sketches and also in one of those illustrating the ,koro-mbasanga range on page #afg4 ,as viewed from the top of ,mariko to the southward1 ,mbatini presents itself as a long mountain-ridge1 trending ,w4,n4,w4 and ,e4,s4,e41 which is connected on the north with ,koro-tambu1 the highest peak of the ,koro-mbasanga ,range1 by a saddle probably not over #a1ejj feet above the sea1 and on the south with the mountain-ridge of ,mariko by a col which appears not to be under #a1jjj feet in elevation4 ,illustration3 ,mount ,mbatini from the top of ,koro-mbasanga4 ,the distant peak on the right is one of the summits of the ,mariko ridge4 ,illustration3 ,view from ,muanaira on the south coast of ,natewa ,bay4 ,my ascent of this mountain was made from the north by the way of the ,lovo valley4 ,in ascending the ,lovo valley one reaches1 at an elevation of about #a1jjj feet1 the foot of the north slope of ,mbatini4 ,the slope is somewhat steep up to #b1jjj feet1 the rocks exposed on the surface being closely similar in the groundmass to those displayed in the upper part of the ,lovo valley4 ,they are compact-looking blackish augite-andesites 7sp4 gr4 #bg71 the very small felspar-lathes of the groundmass1 which are in flow arrangement1 averaging only #je mm4 in length4 ,like the rocks below1 they are a little altered2 and here the interstitial glass is also scanty4 ,but they differ in the absence of rhombic pyroxene and are therefore referred to the augite-andesites 7genus #ac74 ,at #b1jjj feet1 where one crosses the foot-track from ,nukumbolo to ,korolau1 the ascent of the true ,mbatini ridge begins1 the summit lying nearly two miles to the south-east4 ,whilst following along this lofty mountain-ridge we were for the greater part of the time in the rain-clouds1 so that very little was seen of our surroundings4 ,the crest is densely wooded so that our progress was very slow4 ,the rocks are but sparingly exposed4 ,at the commencement of the ridge 7#b1ajj feet7 is displayed an altered hypersthene-augite andesite1 rudely columnar blocks of which1 up to #b feet in diameter1 were lying about4 ,it belongs to genus #a of this sub-class 7see page #bhf7 which also includes the rocks exposed farther along the ridge4 ,in these rocks the felspar-lathes are small 7#je-jg mm4 long7 and are not in flow arrangement4 ,the interstitial glass varies in amount1 and the specific gravity is about #bg4 ,the ascent is very gradual for the first one and a half miles1 when an elevation of #b1fjj feet is attained4 ,from here one ascends the steep-sided peak of ,mbatini1 which rises some #gjj or #hjj feet from the ridge4 ,as one nears the highest point the crest becomes very narrow1 between #ae and #bj feet across2 and on either side there is apparently a drop of several hundred feet4 ,the actual peak1 which is bare and rocky1 is yet narrower2 and when it is enveloped in dense mist as it was in my instance1 it is not a very secure situation for a geologist4 ,it is highly magnetic1 as is the case with most of the other bare peaks of the island4 ,the rocks exposed in the upper #ejj feet1 that is1 in the peak proper1 are highly altered semi-vitreous1 but extensively weathered1 hypersthene-augite-andesites which are referred to genus #a of that sub-class4 ,much of the glassy groundmass is replaced by viridite1 silica1 calcite1 c4 ,less altered specimens display in a brown opaque glass small felspar-lathes averaging less than #a mm4 in length4 ,they exhibit phenocrysts of rhombic pyroxene and augite1 the first prevailing4 ,i did not climb ,soro-levu1 the other of the twin-peaks4 ,its ascent should be made either from ,nukumbolo or from one of the villages on the neighbouring shore of ,natewa ,bay4 ,my acquaintance with ,mbatini1 although very incomplete1 enables me however to point out a few of its general features4 ,as remarked before1 there is a general uniformity in the type of its rocks4 ,the olivine-basalts and basaltic andesites1 prevailing in the ,koro-tini ,range1 are not here represented1 nor are the dacites or acid andesites to be found4 ,the characteristic rocks are more or less altered hypersthene-augite-andesites having a specific gravity in the least altered and least vitreous condition of about #bg2 whilst the average length of the felspar-lathes is always less than #a mm4 ,the same type prevails from the upper part of the ,lovo valley to the summit of ,mbatini2 but it is only in the actual peak that these rocks show much glass in the groundmass1 though extensively affected by alteration4 ,neither tuffs nor agglomerates came under my notice2 but they might be expected to occur on the other slopes4 ,i am inclined to regard this mountain-ridge as a huge dyke-like mass or sill1 representing the remains of a volcanic vent that has been subjected at different periods to marine-erosion and in later ages to sub-aerial denudation4 ,,the ,,vuinandi ,,gap ,i have given this name to the break between the ,thambeyu 7,mount ,thurston7 and ,koro-mbasanga ranges1 where the level of the mountainous backbone of the island descends to about #a1bjj feet above the sea4 ,this is the route taken by the track from ,vuinandi on the shores of ,natewa ,bay across the island to ,lambasa4 ,at ,vuinandi the mountains recede from the coast leaving a broad level plain extending about two miles inland to the village of ,tarawau without rising over #fj feet above the sea4 ,basaltic rocks are exposed in the spurs that descend from the mountains to the coast on each side of the plain4 ,after traversing the low-lying region that lies between ,vuinandi and the main range1 one finds on ascending the eastern slopes1 en route to ,lambasa1 basaltic andesites of the usual type prevailing up to #a1jjj feet4 ,the upper portion of the dividing range1 #a1jjj to #a1bjj feet1 is composed of a more compact basaltic andesite which is often rubbly and in this condition is penetrated by fine cracks1 #a_/h of an inch broad1 filled with chalcedony4 ,this rock1 which has a specific gravity of #bhe1 has a very fresh-looking appearance in the slide1 and the segregation of silica does not therefore appear to arise from an alterative change4 ,the felspar-lathes1 which are in flow-arrangement1 average #aa mm4 in length1 and there is a little residual glass4 ,the mountains rise on either side of the ,vuinandi ,gap to about #b1jjj feet4 ,descending on the west side of the range one follows a stream-course down to a level of #djj feet above the sea1 agglomerates and coarse basic tuffs being exposed on the way4 ,the rocks forming the agglomerates are for the most part to be referred to genus #a of the hypersthene-augite andesites4 ,they are sometimes compact and sometimes amygdaloidal1 the amygdules being formed of chalcedony and other minerals1 whilst the glass of the groundmass is often altered4 ,the track then lay across a spur1 #hjj feet in height1 principally composed of a greyish porphyrite1 exhibiting large opaque crystals of plagioclase1 #d to #g mm4 long1 in an almost holo-crystalline groundmass formed of stout lamellar felspars with large augite granules4 ,it is described on page #bfh under the porphyritic sub-genus of genus #b of the augite-andesites1 and is an unusual type of rock for this island4 ,after this ,i descended into the picturesque gorge of the ,satulaki ,river1 which is only elevated about #bjj feet above the sea1 agglomerates prevailing4 ,in the vicinity of ,satulaki a rather compact basaltic andesite 7sp4 gr4 #bhb7 is commonly exposed in position4 ,it is referred to genus #ac of the augite andesites and belongs to the species with felspar-lathes less than #a mm4 in average length4 ,it occurs both north and south of this place and in the hill-spurs on either side4 ,this is the bed-rock of the ,lambasa plains which here begin and extend to the north coast1 being usually covered with submarine tuffs and clays4 ,,the ,,thambeyu ,,or ,,mount ,,thurston ,,range ,mount ,thurston is the name given in the ,admiralty charts to the highest peak 7#c1abd feet7 of this range4 ,there does not appear to be any general native name4 ,the highest peak visible from the ,lambasa side is known as 8,thambeyu40 ,the lofty mountain-mass1 as it is viewed from ,vuinandi1 is known as ,ulu-i-ndiri-ndiri4#ha ,the whole mountain-range has yet to be properly explored4 ,it is a much more complicated system of mountain-ridges than is indicated in the chart1 my acquaintance with it being restricted to the ,thambeyu ridge1 the elevation of which is #b1fjj feet above the sea4 ,it trends ,n4,n4,w4 and ,s4,s4,e42 but its relation to the highest peak of the range could not be ascertained1 as we were in the rain-clouds during the two days we were on the mountain4 ,i made the ascent from the village of ,numbu-ni-a-vula about three miles to the westward1 which is only #bjj feet above the sea4 ,in the intervening low district a basaltic andesite is exposed in the stream-courses4 ,the structure of the ridge1 as indicated by the ascent of its western slope1 is shown in the accompanying diagram4 ,the core or central axis is formed of massive basic rocks which protrude at the summit and in one or two of the crests of the spurs4 ,the flanks are composed of submarine tuffs and clays overlaid by agglomerates of considerable thickness4 ,the tuffs reach to within #ej feet of the top1 whilst the agglomerates extend to within #djj feet of the summit4 ,the results obtained from this ascent are specially interesting1 since it afforded me the opportunity of studying in a satisfactory manner the junction of the agglomerates with the tuffs4 ,there are two caves on the mountain-side which can be used for night-shelter by those exploring the range4 ,the lowest1 #a1ejj feet above the sea1 is the ,taloko ,cave 7na-ngara-taloko74 ,the highest is the ,ndromo ,cave1#hb #b1ajj feet1 known to the natives as 8na-ngara-vatu-ni-ndromo40 ,like most of the caves all over the island they occur at the junction of the agglomerates and tuffs1 and are to be attributed to the more rapid weathering of the underlying tuffs4444 ,in describing the results of my examination of this mountain-ridge1 ,i will deal in succession with the tuffs1 the agglomerates1 the junction between these two deposits1 and the axis or core of basic rocks4 ,illustration3 ,image3 ,ideal ,section of ,thombeyu 7#a7 ,the submarine tuffs and tuff-clays4--,as exposed in the stream-courses near and at the foot of the mountain and as high as the ,taloko ,cave1 these deposits are bedded horizontally4 ,at higher levels1 owing to insufficient exposure the bedding is not so clear4 ,up to #gjj or #hjj feet coarse palagonite-tuffs prevail2 but they do not effervesce with an acid1 and apparently contain but scanty organic remains4 ,at #iej feet coarse and fine sedimentary tuffs alternate1 the last being greenish foraminiferous tuff-clay rocks1 somewhat compacted and containing #aj per cent4 of carbonate of lime4 ,the tests of the foraminifera1 which are abundant and of the ,globigerina type1 are filled with calcite4 ,several fragments1 of a semi-vitreous basic rock1 not however exceeding #b mm4 in size1 are inclosed in the deposit2 but the mass of it is made up of yet finer materials of the same rock1 palagonitic detritus1 plagioclase fragments1 fine calcitic debris1 tests of foraminifera1 c4 ,these fine tuff-clays were evidently formed in relatively deep-water4 ,at the ,taloko ,cave 7#a1ejj feet71 where there are exposed rather coarse tuffs containing bands about a centimetre thick of a fine clay-tuff1 the last-named effervesce freely with an acid1 whilst the first contain only a little carbonate of lime4 ,no sections have been made of these deposits2 but when powdered and examined under the microscope they appear to have the same general composition as the deposit described above from an elevation of #iej feet4 ,they are probably foraminiferous though scantily4 ,the tuffs found at the ,ndromo ,cave 7#b1ajj feet7 contain #d per cent4 of carbonate of lime and small tests of foraminifera are visible with a lens4 ,the mineral fragments include plagioclase and rhombic pyroxene1 and there are inclosed rounded gravel-fragments1 #e mm4 in size1 of a semi-vitreous rock4 ,palagonitic debris make up the mass of these tuffs4 ,a coarse deposit from #b1ejj feet is non-calcareous1 but has the same general composition4 7#b7 ,the agglomerates4--,these deposits are best represented in the upper part of the mountain1 between #a1ejj and #b1bjj feet above the sea4 ,here they often present vertical precipices having a drop varying between #ajj and #djj feet1 with the submarine tuffs exposed at their base4 ,such cliffs1 however1 display no structure4 ,their vertical faces are to be attributed to joints and to the extensive 8slips0 that frequently occur on these slopes1 when large masses of agglomerate1 undermined by the percolation of springs through the tuffs beneath them1 roll far down the mountain-sides4 ,the blocks of the agglomerates are fairly uniform in size1 being usually #d or #e inches across4 ,they are composed of a semi-vitreous hypersthene-augite andesite1 containing both augite and rhombic pyroxene1 but of an unusual type4 ,it is a blackish rock carrying opaque phenocrysts of plagioclase1 and is characterised by the prismatic form of the pyroxene 7monoclinic7 of the groundmass4 ,a very similar rock from the ,sokena agglomerates has been before described4 ,it is referred to genus #ah of the class1 and the prismatic sub-order to which that genus belongs is described on page #bhi4 7#c7 ,the junction of the agglomerates and submarine tuffs4--,this is well displayed at the ,taloko ,cave4 ,here the agglomerates lie conformably on the sedimentary tuffs2 but the line of junction is sharply defined and the only evidence of transition is afforded by the great diminution in the size of the blocks of the agglomerates1 which are #a to #b inches across4 ,immediately beneath the agglomerate is a layer #b centimetres thick of a rather coarse sedimentary palagonite-tuff having the composition of the deposits above described1 but not effervescing with an acid1 and showing no foraminiferous tests4 ,the size of its 8grain0 is about a millimetre4 ,this passes downward rather abruptly into a chocolate-coloured marl-like rock1 a centimetre thick1 which is formed of the same materials but in a clayey condition4 ,beneath this is the calcareous foraminiferous palagonite-tuff referred to in the first paragraph4 ,it is apparent that for some time before the agglomerates began to accumulate on the sea-bottom there had been a fairly uniform deposit of submarine tuffs1 evidently in rather deep water4 ,then followed a period during which the finest mud was deposited which is represented by the thin layer of chocolate-coloured clay4 ,this was succeeded by the deposition of coarser sedimentary tuffs forming a layer about an inch in thickness4 ,then commenced the accumulation of the agglomerates1 of which the materials were at first small and afterwards larger in size4 7#d7 ,the core or axis of volcanic rocks4--,this is represented on the summit by masses1 #b to #e feet across1 of two kinds of hypersthene-augite andesite1 which are referred to genus #a of that sub-class4 ,one is a compact grey rock 7sp4 gr4 #bgb7 carrying phenocrysts both of rhombic and monoclinic pyroxene1 the former prevailing1 and displaying a small amount of interstitial glass4 ,it is magnetic and exhibits marked polarity1 as noticed in ,chapter ,,xxvi4 ,the other is a scoriaceous rock containing numerous round steam-pores1 ranging up to #e millimetres in diameter and generally filled with clear quartz-crystals and lined by chalcedony4 ,it contains semi-opaque glass in abundance1 and is apparently a semi-vitreous form of the rock just described4 ,both rocks are to some extent altered4444 ,on the crest of a spur1 #ejj feet below the summit1 is exposed in position an augite-andesite1 assigned to genus #ac1 sub-genus #a1 species ,b1 of that sub-class4 ,it is non-scoriaceous and exhibits a considerable amount of greenish alteration products4 7,sp4 gr4 #bgi47 ,,the ,,avuka ,,range ,this high range1 which lies immediately to the east of ,lambasa1 attains its greatest elevation in ,mount ,avuka1 which is #a1igf feet above the sea4 ,it represents the extension northward to the coast of the inland ,thambeyu mountains that culminate in ,mount ,thurston4 ,in its upper portion ,mount ,avuka presents bare precipitous faces apparently of agglomerates and some hundreds of feet in height4 ,my acquaintance with this range is scanty4 ,in a traverse from ,lambasa to ,ngele-mumu ,i crossed it a mile or more south of ,mount ,avuka1 where it is only #gjj feet in elevation4 ,i also rounded the end of the range where it reaches the coast between ,lambasa and the valley of ,mbuthai-sau4 ,this last locality1 which is described on page #bah1 derives especial interest from the circumstance that here the regions of basic and acid rocks meet4 ,the basic rocks that occupy nearly all the sea-border from ,naivaka to ,lambasa here become mingled with1 and finally give place to1 the acid rocks which prevail in all the region eastward as far as ,undu ,point4 ,in crossing the range on the way from ,lambasa to ,ngelemumu1 ,i noticed as high as #dej feet basic non-calcareous tuffs displaying a concretionary arrangement suggestive of the proximity of an intrusive igneous rock4 ,further up the western slope occur basic agglomerates1 whilst at and near the top 7#gjj feet7 there lie on the surface large boulders of a dark grey hypersthene-gabbro having a specific gravity of #bg and belonging to the type of plutonic rocks described on page #bdi4 ,it is very probable that this gabbro forms the axis of the range2 and we have here no doubt one of the oldest of the mountain-ridges in the island4 ,,chapter ,,xiii ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,valanga ,,range ,,this range1 which trends ,n4,w4 and ,s4,e4 between the ,mariko mountain-ridge and the head of the valley of ,na ,kula1 attains a height of #a1hhj feet at its ,n4,w4 and of #a1gaj feet at its ,s4,e4 end4 ,the average elevation1 however1 is probably not over #a1cjj or #a1djj feet4 ,my acquaintance with the range is only partial1 but it is sufficient to bring to light some of its leading structural features4 ,those who follow me will find in these mountains a very interesting region for their geological explorations4 7#a7 ,,traverse ,,of ,,the ,,valanga ,,range4--,in making the journey from ,valanga to ,vunimbua1 ,i crossed the range where its elevation was about #a1cjj feet4 ,basic agglomerates1 containing sometimes amygdaloidal blocks1 are displayed in the low district between ,valanga and the foot of the range4 ,in the stream-course at the base of the slope the deeper seated rocks of the range are at once exposed4 ,large masses1 #e or #f feet across1 of altered grey pyroxene andesites lie in the bed of the stream4 ,some of them show opaque porphyritic felspar and have the appearance of porphyrites 7sp4 gr4 #bfg74 ,they belong to the type described on page #bga under genus #f of the augite-andesites4 ,others are grey propylitic varieties of a basic semi-doleritic andesite penetrated by cracks containing calcite1 and displaying in a groundmass1 exhibiting much viridite and a little pyrites1 calcitic pseudomorphs of the felspar phenocrysts and more or less parallel felspar-lathes1 #ae mm4 long and somewhat altered4 ,another of the deeper-seated rocks commonly exposed on the upper west slopes of the range is a dark grey rock showing much porphyritic pyroxene 7sp4 gr4 #bgb74 ,it has a micro-felsitic groundmass and is referred to the fourth order of the hypersthene-augite-andesites described on page #bia4 ,about two-thirds of the way up the western slope of the range1 there is exposed a coarse palagonite-tuff1 evidently an incrusting deposit4 ,stout crystals of augite can be picked out of it1 and it contains also lapilli up to an inch in size of a basic vesicular semi-vitreous basalt4 ,descending the eastern slopes one observes between #a1bjj and #a1jjj feet large blocks of the same grey hypersthene-augite-andesite above mentioned and of a grey granitoid rock of the gabbro type4 ,this last is a hypersthene-gabbro with specific gravity of #bge1 and belongs to the group of plutonic rocks described on page #bej4 ,its pyroxene phenocrysts are often represented by fibrous bastite4 ,one can scarcely doubt that this gabbro is the plutonic equivalent of the prevailing grey pyroxene-andesites4 ,lower down the slope only small fragments of rocks were exposed1 probably derived from an agglomerate4 ,one of the specimens here obtained is a doleritic basaltic andesite 7sp4 gr4 #bgg74 ,another is a very interesting rock displaying large porphyritic crystals of a mineral like bronzite in a groundmass originally to a large degree vitreous2 but the glass is now replaced by viridite and secondary crystalline silica4 ,the 8bronzite0 is the result of the conversion of associated rhombic and monoclinic pyroxene into fibrous bastite4 ,from the results of the traverse across this part of the ,valanga ,range it may be inferred that more or less altered grey basic andesites passing into gabbros chiefly compose it4 ,no doubt at one time it was largely covered with basic tuffs and agglomerates1 but these deposits have been almost completely stripped off by the denuding agencies1 and were only noticed in one place on the western flank4 ,that the northern part of the range towards the ,mariko ridge has a similar structure is shown by the character of the loose blocks in the upper course of the ,vunimbua ,river1 which takes its rise on these slopes4 ,amongst those in the river above the village ,i noticed a solitary block of a coarsely crystalline diorite containing prisms of brown hornblende a centimetre in length4#hc ,but the rocks most frequently represented were propylitic grey hypersthene-andesites1 in which the pyroxene is mostly changed into bastite1 whilst the surface often sparkles with pyrites 7see page #big74 7#b7 ,,ngone ,,hill4--,this is a curious conical hill1 about #gjj feet in height1 that rises up on the right side of the ,vunimbua ,river about #a miles above the village of that name and near the foot of the range4 ,it evidently represents a 8volcanic neck10 and doubtless this vent was the source of the large blocks forming the basic agglomerate that occurs in huge masses in the river-course in the vicinity of this hill4 ,on its lower flanks is exposed a hard compacted tuff1 showing pyroxene crystals1 which is composed principally of fragments of a palagonitised vacuolar basic glass1 the minute cavities being often filled with opal4 ,in the upper part of the hill is displayed a massive altered augite-andesite penetrated by fine veins of chalcedony4 ,numerous irregular cavities filled with the same material occur in its dark opaque glassy groundmass4 ,the blocks of the agglomerates found in the vicinity of the hill vary in size from #d to #ah inches4 ,they are composed of a compact blackish semi-vitreous basic andesite 7sp4 gr4 #bgc7 of the type characteristic of the basic agglomerates over most of the island4 ,the matrix of the agglomerate is hard and somewhat altered1 and is chiefly made up of fragments1 ranging up to #e mm4 in size1 of a vacuolar basic glass1 sometimes but slightly changed1 though usually converted into palagonite1 the vacuoles being filled with chalcedonic opal4 ,the large masses of coarse tuffs displayed in the bed of a stream-course close to ,ngone ,hill are non-calcareous and composed of palagonitic materials4 ,palagonite-tuff clays are also exposed in the river-course a little above ,vunimbua4 ,about half-way between the village and the hill there occurs in position at the river-side an amygdaloidal basic rock1 the amygdules being formed of chalcedonic opal4 ,it is apparent that this hill represents a lesser vent which probably dates back to the period before the emergence4 ,all the products of its eruption are1 however1 more or less altered4 ,from the absence of sorting in the blocks of the agglomerates1 and from the character of the matrix1 it may be inferred that these deposits have been accumulated directly from the ejected materials without the intervention of the agency of marine erosion4 7#c7 ,,the ,,western ,,flank ,,of ,,the ,,valanga ,,range4--,one of the boldest pieces of coast in the island lies on the eastern side of ,savu-savu ,bay1 between the mouth of the ,ndreke-ni-wai ,river and ,valanga ,harbour4 ,here a number of lofty headlands separated by broad valleys descend with precipitous fronts to the shore1 some of them1 as in the case of the ,nambathi promontory on the north side of ,valanga ,harbour1 retaining an elevation of #a1jjj feet within a few hundred yards of the coast4 ,by following the coast-track from the ,ndreke-ni-wai ,river to ,valanga one crosses some of these headlands4 ,as far as ,vatu-lele altered red tuffs1 basic agglomerates1 and massive basaltic andesites are the prevailing rocks4 ,the red tuffs exhibit a double alteration4 ,they were originally composed of finely pulverised basic vacuolar glass1 which subsequently became palagonitised1 and afterwards there was an extensive deposition of chalcedonic silica and of red iron oxide4 ,no organic remains appear to exist2 whilst the scanty calcite present is evidently an alteration product4 ,where the road 8tops0 the headland on the north side of ,vatu-lele ,bay1 there is exposed a dyke-like mass of a rubbly semi-vitreous basaltic rock penetrated in all directions by veins1 #a to #c inches thick1 of a tachylytic glass1 splinters of which fuse readily in the ordinary spirit-lamp flame4 ,the numerous fissures were doubtless produced during the consolidation of the rock2 and subsequently they were filled with the still fluid residual portion of the magma1 which would be composed of the most fusible constituents4 ,this subject1 which bears on the origin of palagonite1 is discussed in ,chapter ,,xxiv4 ,between ,vatu-lele and ,urata1 palagonite-tuffs and basic agglomerates are chiefly displayed4 ,on the north slope descending to ,urata there is exposed in the foot-path a dyke-like mass of a dark-grey hornblende-pyroxene-andesite1 an unusual type of rock which is described on page #bih4 ,just south of ,urata ,i observed an agglomerate containing large blocks1 #c or #d feet across1 of the deeper-seated altered grey pyroxene-andesites that with the gabbros and diorites form the axis of the range4 7#d7 ,,the ,,valley ,,of ,,na ,,kula4--,in crossing from ,sava-reka-reka to ,natewa ,bay1 one ascends the remarkable valley of the ,kula and traverses the ridge at its head4 ,this ridge1 which is about #gjj feet in height and forms the termination of the ,valanga ,range1 is composed of altered grey hornblende-pyroxene-andesites and of similar holo-crystalline rocks representing the gabbro or plutonic type of the same4 ,one of these rocks is described on page #bej1 under the head of hornblende-gabbro4 ,another is referred provisionally to the hypersthene-gabbros 7page #bdi72 but it is extensively occupied by chlorite1 viridite1 and other alteration products4 ,here1 as with the other rocks of the ,na ,kula ,ridge1 the plagioclase phenocrysts are opaque1 the result of the numerous fine cracks with decomposition products in the interior of the crystals4444 ,it is thus seen that in general structure the ,na ,kula ,ridge represents the main axis of the ,valanga ,range to the north4 ,the valley of ,na ,kula is occupied by a river which does not empty itself1 as one would expect1 into ,savu-savu ,bay1 but turns off sharply to the south at right-angles to its previous course1 and after breaking through the coast range1 opens into ,naindi ,bay4 ,this peculiarity has attracted the attention of the natives4 ,the village of ,sawa-,ndrondro1 which lies about #a miles up this valley1 is not elevated more than #ej feet above the sea4 ,the gradient is evidently not only very slight but is also irregular1 so that in their upper course about #c miles inland1 where the elevation is only #acj feet1 the waters of the river are partially checked in their flow and form extensive swamps where the 8vitho0 or wild sugar-cane flourishes4 7#e7 ,,concluding ,,remarks ,,on ,,the ,,valanga ,,range4--,it may be inferred from the geological structure of the range that it is one of the oldest in the island4 ,the agglomerates and tuffs that enter so largely into the formation of most of the other mountain-ridges are here to a great extent absent1 except in the lower flanks2 and we have exposed the axis of the range composed of more or less altered grey pyroxene and hornblende-pyroxene andesites passing1 as appears to be the case1 into gabbros and diorites4 ,it is true that the exposure of the gabbros is limited and that only a single block of diorite came under my notice2 but this might be looked for where the plutonic rocks are deeply seated4 ,although far overtopped by the neighbouring agglomerate mountain-ridge of ,mariko1 the ,valanga ,range would seem to date back to a much earlier stage in the history of the island4 ,,the ,,mountain-,,ridge ,,of ,,mariko ,this mountain-ridge1 which trends nearly east and west and joins the ,valanga ,range1 rises in mass to a height of rather over #b1jjj feet4 ,above this elevation it terminates in several short conical peaks1 of which the highest1 #b1hij feet1 is named ,mariko1 the ,drayton ,peak of the chart4 ,one of the peaks1 lying a little to the east of the summit1 and apparently between #ajj and #bjj feet lower1 is called the ,vatu-mbutho or ,white ,rock4 ,in the profile of the range1 as seen nearly 8end-on0 from the distant south shore of ,natewa ,bay1 it would appear to be rounded in its upper part4 ,its true outline1 however1 when viewed in length1 is1 as described above1 namely1 a massive ridge with various peaks4 ,when viewed from the top of the hills behind ,valanga1 this mountainous range has a very imposing appearance4 ,on the south side it rises precipitously to the summit1 but the northern slopes below an elevation of #a1hjj or #a1ijj feet descend with a very easy gradient for #a or #b miles into the valley of the river ,ndreke-ni-wai4 ,in the first case the average angle of the slope would be from #ae to #bj degrees and in places often more2 whilst in the second case the average inclination would be about #g degrees4 ,the contrast between the two sides of the range is very striking and one ought1 ,i think1 to find a parallel in the broken-down rim of a large crater with a gentle outer slope and a precipitous inner face4 ,when descending recently the outer slope of ,monte ,somma1 the ancient ,vesuvian vent1 ,i found reproduced some of the features of the northern slope of ,mariko4 ,the tuffs and agglomerate-tuffs that cover their outer flanks are in both mountains deeply scored by the gorges and ravines worn by the torrents4 ,after the description of the geological structure of the ,mariko ,range1 we shall perhaps be in a better position to consider this question2 but until a proper survey of the region has been made it will not be possible to give a final answer4 ,there are also many other uncertainties which would be removed by the accurate mapping of the district1 such for instance as the mode of connection between the ,mariko and ,valanga ,ranges4 ,the highest peak of the ,mariko ,range is irregularly square-topped and is only a few paces across4 ,it has a soil-cap and supports small trees and shrubs1 whilst there is a precipitous rocky face on the east and south4 ,like most of the other lofty peaks of the island it is magnetic1 and as remarked on page #cfh1 it markedly deflects the compass-needle4 ,i made two ascents of this mountain from ,vunimbua1 one to the highest peak 7#b1hij feet71 and the other across the range to ,nukumbolo at a point half a mile or more to the west of the summit1 where its elevation is #b1bjj feet4 ,basic agglomerates and agglomerate-tuffs prevail on both the slopes up to #a1hjj or #b1jjj feet1 the blocks being composed of a dark semi-vitreous basic andesite referred to the hypersthene-augite sub-class with specific gravity #bge4 ,it contains much glass in the groundmass1 and since the pyroxene of the groundmass is prismatic1 this rock belongs to the prismatic sub-order described on page #bhi4 ,ordinary basic tuffs are also well represented on the north flank4 ,on the south or precipitous side they are usually more or less altered4 ,here1 for instance1 they may take the form of a hard breccia-tuff containing vesicular lapilli1 up to half-an-inch in size1 of a semi-vitreous basic rock1 the small steam-holes being either empty or filled with opal or chalcedony4 ,the matrix of the rock is made up of finer fragments of a basic vacuolar glass1 showing a few felspar microliths1 but often more or less palagonitised4 ,evidence of further alteration is afforded by the small cracks and crevices filled with chalcedony4 ,other altered tuff-rocks are exposed on the south slope4 ,at an elevation of #djj-dej feet above the sea1 and underlying the agglomerates and breccia-tuffs1 ,i found exposed in a stream-course a hard dark rock looking like a compact andesite4 ,under the microscope1 however1 it is shown to be an altered palagonite-tuff composed in part of angular fragments of plagioclase and of rhombic and monoclinic pyroxene1 not exceeding #ae mm4 in size1 and containing also similar-sized fragments of a basic hemicrystalline rock4 ,the base is made up of palagonitic material and contains a few 8,globigerina0 tests sometimes displaying calcite in their interior4 ,fine cracks filled with chalcedonic silica testify to a subsequent alteration of the deposit4 ,at #a1ejj feet occurs a hard red altered palagonite-tuff1 having a similar composition and being altered in like fashion1 but not displaying tests of foraminifera in the slide4 ,the foregoing remarks refer to the main undivided mass of the range1 that is1 up to #b1jjj feet4 ,the highest peak of ,mariko probably represents in structure the other peaks rising to various heights on either side of it4 ,here1 at elevations between #b1jjj feet and the summit1 a rubbly agglomerate prevails of a somewhat different character from that occurring at lower levels4 ,it is well exposed in some cave-cliffs at a height of #b1ejj feet and also in the rocky face of the peak4 ,the rock composing the blocks is a dark-grey aphanitic augite-andesite 7sp4 gr4 #bfe71 referred to genus #bj of that sub-class and displaying prismatic pyroxene in the groundmass4 ,smoky residual glass exists usually in fair amount2 whilst in the blocks of the cave-cliffs it is so abundant that the rock may be termed semi-vitreous4 ,in the locality just named the blocks are scoriaceous1 the steam-pores1 which are drawn out to a length of #e or #f mm4 and more1 being partially or completely filled with calcite and occasionally with opal4 ,at times the steam cavities are much larger4 ,in one of my specimens there is an elongated cavity #e cm4 7#b inches7 in length1 which has a thin lining of chalcedony1 from the surface of which pyramidal crystals of calcite project into the interior4 7,i found the same grey andesite exposed in situ lower down the south slope at an elevation of #a1hjj feet1 but non-scoriaceous47 ,the matrix of the agglomerate principally consists of fine palagonitic material with small fragments of plagioclase and pyroxene but apparently no lime4 ,at heights of about #b1hjj feet on the south side of the peak1 and of #a1fjj feet on the north flank of the range1 are exposed non-calcareous greyish tuffs remarkable for the quantity of crystals of rhombic pyroxene1 entire and in fragments1 that they contain4 ,this is a characteristic feature of the more acid andesitic tuffs of the island1 and it is to these deposits that the ,mariko tuffs in question make a near approach4 ,they contain at times subangular fragments of more basic rocks2 and are true tuffs in the sense that although perhaps deposited on a sea-bottom they represent the ejected materials of a subaerial vent4 ,the crest of the range1 where it is crossed by the road from ,vunimbua to ,nukumbolo and for #bjj feet below1 is formed of a decomposed rock1 perhaps a breccia4 ,a fragment of the rock obtained from the crest is a grey somewhat altered hypersthene-augite andesite 7sp4 gr4 #bge7 with an orthophyric groundmass1 and referred to the order described on page #bij4 ,this rock may be connected with the tuffs above alluded to4444 ,reference may here be made to a black basaltic rock 7sp4 gr4 #bhh7 of which1 at an elevation of #b1ejj feet at the foot of the peak1 ,i found a portion of a columnar block about #ah inches across4 ,it may prove to be an olivine-basalt2 but no section has been made of it4 ,it is apparent from the foregoing description of the ,mariko ,range that in general structure it does not differ materially from the other mountain-ridges of the island1 although in the types of the rocks it presents some variety4 ,here also we have agglomerates prevailing on the flanks and forming the summit4 ,as far as the characters of the rocks can guide us1 we cannot determine whether the range has been built up by a number of vents on a great fissure1 or whether it represents the remains of a huge crater4 ,in this uncertainty we can only appeal to the contrast between the gentle gradient of the north slopes and the precipitous descent of the south slopes as favouring the last supposition4 ,we cannot1 however1 doubt that the agglomerates of the upper portion of the range are the products of an eruptive vent or of vents that rose above the surface of the sea1 since the blocks are all of one kind of andesite and are often scoriaceous4 ,we can be fairly certain that at such a time the lower slopes were in part submerged1 seeing that foraminiferous tuffs underlying the agglomerates are now exposed4 ,but we have to distinguish between these submarine basic tuffs of the lower slopes which may in part be the result of marine-erosion and the grey rhombic-pyroxene-tuffs of the upper levels which are probably derived from subaerial eruptions4 ,,the ,,savu-,,savu ,,peninsula ,i include in this district the promontory west of ,naindi ,bay and ,sava-reka-reka ,bay4 ,although its surface is much cut up1 it has1 when viewed from a distance1 a fairly even profile and attains a maximum height of rather over #hjj feet4 ,from the region east of it1 it is separated by the ,naindi ,gap4 ,here one can cross the peninsula between the two bays above named without rising more than #ej feet above the sea4 ,the elevated interior is divided into two parts1 which are divided by a col1 about #bej feet in elevation1 which is ascended in crossing from ,naithekoro on the south coast to ,na ,kama on the north coast4 ,much of the surface is clothed with the usual 8talasinga0 vegetation4 ,close to the north shore1 with which it is connected by the reef-flat1 rises the small island of ,na-,wi1 and off the extremity of the peninsula1 which is known as ,harman's ,point1 is the islet of ,naviavia1 formed of raised reef-limestone as described on p4 #h4 ,the celebrated boiling springs known as ,na ,kama are situated on the north coast opposite ,na-,wi4 ,it may be remarked in passing that besides finding an exit in the springs1 the hot water oozes through the beach and below the tide-marks for several hundred yards along the shore4 ,these springs are described in detail on p4 #be4 ,this is one of the few districts of the island in which elevated reef-masses occur at the sea-border4 ,these old reefs1 which attain a maximum elevation of #bej feet above the sea1 are principally restricted to the neighbourhood of ,naindi ,bay4 7,they are referred to in detail in ,chapter ,,ii47 ,but they indicate only a part of the submergence which this region has experienced4 ,there is an exposure of a very interesting rock in a stream-course that is crossed on the road from ,yaroi to ,naindi1 less than a mile from the first-named place1 and about #cj feet above the sea4 ,here we find a dark1 impure 8,globigerina0 limestone1 or1 as it might be also designated1 an altered calcareous palagonitic clay-tuff4#hd ,the larger fragments in it average only #b mm41 and it affords evidence of a period of submergence during which the hill-tops of the ,savu-savu ,peninsula were below the sea-level4 ,we get the same indication1 but in a more pronounced degree1 in the stratified sedimentary clay-tuffs which are exposed on the shore-flat of the south side of the neighbouring ,sava-reka-reka ,bay4 ,these beds1 which within a distance of fifty paces are inclined #aj-ae to the south-west and the same amount to the north-west1 have apparently a ququversal dip4 ,in places they exhibit a spheroidal and concentric structure1 and are penetrated by cracks containing some calcite1 but mostly filled with a white zeolitic mineral4#he ,one of these rocks is a bright green1 hard and compact deposit1 containing but little lime1 and evidently an altered palagonitic clay-tuff4 ,it contains a few minute tests of the 8,globigerina0 type2 and on account of the small size of its fragments of minerals1 which range from 4#ja to 4#jd mm41 it may be regarded as a relatively deep-water sediment4#hf ,it is interstratified with a coarser1 somewhat altered palagonite-tuff1 which shows but little lime and only a suspicion of tests of foraminifera4 ,the size of the larger included fragments does not exceed half a millimetre4444 ,the low hill1 near ,yaroi1 on which the magistrate's house is built1 is composed of fine and coarse tuffs1 probably submarine4 ,it is doubtful whether any but sedimentary tuffs occur in this peninsula4 ,in the hills of the western part of the peninsula1 that is1 west of ,na ,kama and ,naithekoro1 a particular type of basaltic andesite prevails1 characterised by rhombic pyroxene as well as augite phenocrysts1 and referred for the most part to genus #ac of the hypersthene-augite andesites4 ,their specific gravity ranges from #bgf to #bhc1 and the interstitial glass may be fair or scanty in amount4 ,the average length of the felspar-lathes is unusually small1 #jd-jf mm4 ,in these respects the basaltic andesites of the ,savu-savu ,peninsula differ from the basaltic andesites found in most other parts of the island1 where1 as exemplified by those of the ,wainunu1 ,solevu1 and ,seatura regions1 the felspar-lathes average between #a and #b mm4 in length1 and there is practically no rhombic pyroxene4 ,a somewhat scoriaceous semi-vitreous form of pyroxene andesite is exposed on the south slopes above ,nukumbalavu1 where it is covered by basic agglomerates4 ,the pyroxene in the groundmass is here prismatic1 and not granular1 and for the most part rhombic2 and the rock is referred to the prismatic sub-order of the hypersthene-augite andesites described on p4 #bhg4 ,the basaltic andesites of the peninsula are often extensively decomposed through the weathering process1 a spheroidal structure being then displayed4 ,it rarely happens that the basaltic rocks of this locality assume a propylitic character4 ,yet1 if this change is due to hydrothermal metamorphism1 we ought to find altered rocks of this kind in the vicinity of the boiling-springs4 ,such rocks did not come under my notice at the surface2 but this only indicates that if this alteration has taken place here1 it has been effected at some depth2 and1 indeed1 it would seem probable that the alteration known as 8propylitic0 is a change produced generally in deep-seated rocks4 ,a semi-ophitic basaltic andesite that is exposed in the small stream-course at the back of the springs1 and not #ajj yards distant1 displays no propylitic change1 and is only affected by hydration4 ,the basaltic andesites found on the hill-slopes further inland from the springs exhibit no change of such a nature4 ,however1 rocks of this description occur at and near the coast about a mile to the westward4 ,one of them1 which is light green in colour1 might be taken for a limestone1 since it effervesces with an acid4 ,when examined in the slide it is shown to be the prevailing basaltic andesite greatly altered4 ,the porphyritic rhombic pyroxene is replaced by viriditic material2 the plagioclase phenocrysts are replaced by calcite1 secondary silica1 and other alteration products2 and the structure of the groundmass is disguised by chalcedony1 calcite1 viridite1 c4 ,another rock from this locality displays great alteration4 ,the structure of the groundmass is obscured by secondary silica1 and is traversed by fine cracks passing through the felspar phenocrysts and filled with blood-red films of hematite4 ,on the hill-slopes behind ,harman's ,point1 at an elevation of #cjj to #djj feet1 blocks of a reddish1 volcanic rock1 greatly altered by the deposition of silica1 were displayed on the surface4 ,the ground was here strewn in places with beautiful pyramidal prisms of clear quartz1 ranging up to an inch in length4 ,they contain numerous inclusions1 their faces being sometimes deeply etched or eroded4 ,these crystals appear to have been formed rather rapidly in some highly siliceous thermal underground waters4 ,i did not ascend the hills of the portion of the peninsula lying east of ,na ,kama and ,naithekoro4 ,but whilst crossing the saddle between these two places1 ,i perceived that the prevailing basaltic andesites extended up the slopes to the east4 ,the neighbourhood of ,naindi ,bay offers several features of interest4 ,the bay1 which is circular in shape1 is closed in on the east and west by projecting points1 where we find elevated reef-limestone1 #dj or #ej feet above the sea1 displaying massive corals and large 8,tridacna0 shells in their natural position1 and overlaying a cement-stone composed of blocks of volcanic rocks in a calcareous matrix4 ,on the beach on the west side of the bay there is exposed a reddish-grey altered pyroxene-andesite1 which1 as regards the size of the felspars of the groundmass and other characters1 appears to be an altered form of the prevailing basaltic andesites of the peninsula4 ,in the midst of the low passage that isolates the peninsula1 which ,i have termed the ,naindi ,gap1 there is displayed a highly altered basic andesite which contains a white1 zeolitic mineral in its numerous cracks4 ,the small island of ,na-,wi consists of two low hills1 the highest #acj feet in height1 connected by a mangrove swamp and a sandy beach4 ,there is no trace of a crateral cavity4 ,the prevailing rock is a porphyritic1 compact1 basic andesite1 differing from the other rocks of the neighbourhood in the greater amount of glass it contains4 ,though it is not easy to find a good1 unweathered specimen of the rock1 it would appear that ,na-,wi represents an old volcanic neck4 ,we may infer from the above description of this peninsula that it has a history similar to that of most other parts of the island4 ,there is evidence in the upraised reefs and in the 8,globigerina0 clays and limestones of considerable submergence at one period2 and it is highly probable that the prevailing basaltic andesites are the products of submarine eruptions4 ,in my account of the hot springs given on page #bf1 reference is made to the absence of any trace of a crateral cavity in that locality4 ,the same is true1 as far as my observation goes1 of the whole peninsula4 ,altered rocks do not occur in the vicinity of the springs1 but they are to be found at distances a mile and more away4 ,it does not seem possible to restore in imagination the original form of this part of the island4 ,the present contours are the results of more than one reshaping of the surface through the agencies of marine erosion and sub-aerial denudation4 ,,the ,,district ,,between ,,naindi ,,bay ,,and ,,the ,,salt ,,lake ,three or four of the peaks of this hilly district rise to about #a1jjj feet or rather over1 the highest being that of ,na ,suva-suva1 which attains a height of #a1aaj feet4 ,since my acquaintance with this region is incomplete1 ,i will confine my remarks to the localities actually examined4 ,through the kindness of ,mr4 ,f4 ,spence1 ,i was able to make use of a track cleared to the top of ,na ,suva-suva4 ,this eminence1 which forms a conspicuous landmark for many miles1 both landward and seaward1 has a rounded summit and is to all appearance an old volcanic neck4 ,it is composed in mass in its upper half of a heavy dark olivine-basalt 7sp4 gr4 #cja71 seemingly non-columnar1 and referred to the highly basic rocks forming genus #af of the olivine-basalts4 ,there is such a thick soil-cap on the lower slopes that ,i was unable to ascertain the character of the rocks there4 ,it is1 however1 noteworthy that a very similar olivine-basalt 7sp4 gr4 #bii7 crops out on the coast south of this hill and to the east of ,naindi ,bay4 ,they both contain abundant small olivine-phenocrysts and a little residual glass1 the felspar-lathes averaging #a-ad mm4 in length4 ,since their localities are rather more than a mile apart1 it is not possible to say without a further examination of the locality whether or not we have here the same intrusion4 ,on the coast between ,naindi ,bay and ,salt ,lake ,passage1 calcareous tuffs1 probably fossiliferous1 are occasionally exposed in the low spurs descending to the sea1 whilst islets of elevated reef-rock front the beach4 ,the coast immediately west of the ,salt ,lake ,passage is of exceptional interest4 ,here the sea-cliffs and the shore-flat are formed of an agglomerate tuff penetrated in all directions by veins of calcite1 an inch and under in thickness4 ,the matrix of this deposit1 which is a little calcareous1 is principally made up of fragments1 ranging up to #c or #d millimetres in size1 of vacuolar palagonite1 the minute vesicles being filled with some alteration product4 ,it also contains large macled augite crystals #e or #f mm4 in size1 which can be picked out in numbers by the fingers4 ,the blocks vary from a few inches to two feet across1 and are usually composed of an augite-andesite1 containing large porphyritic crystals of augite1 and are often amygdaloidal1 the amygdules1 #c or #d mm4 in size1 being formed of a zeolite4 ,but blocks of very different rocks also occur in this agglomerate tuff4 ,one1 about two feet across1 was composed of a coarsely crystalline diorite made up1 as described on page #bea1 of large crystals of hornblende1 #b to #be centimetres long1 and of large opaque crystals of acid labradorite4 ,another was made of hornblende-hypersthene andesite belonging to the ortho-phyric order of that sub-class 7see page #bii74 ,there is a little altered glass in the groundmass1 and large secretions of brown hornblende1 more than an inch in size1 are to be observed in the rock4 ,it is probable that this singular deposit represents a submarine accumulation of materials ejected from some neighbouring vent4 ,organic remains did not come under my notice2 but apart from the palagonitic character of the matrix and the abundance of veins of calcite1 the submarine origin is indicated by the existence of upraised reefs in the coast districts east and west of this locality4 ,the block of diorite affords an important clue as to the character of the deep-seated plutonic rocks in this part of the island4 ,a similar diorite was found by me amongst the blocks in the bed of the ,vunimbua ,river2 and on page #ahe1 reference is made to the probability of such rocks forming the nucleus of the ,valanga ,range4 ,the hills on the west side of the ,salt ,lake are worth further examination4 ,on the coast of the ,natewa ,bay side of this district1 in the vicinity of ,vuni-tangaloa and between that place and ,vuni-sawana1 there are displayed agglomerates formed of blocks of hornblende-andesite1 some of the specimens being very similar to that obtained from the block of hornblende-andesite noticed in the agglomerate-tuff on the neighbouring south coast4 ,,the ,,salt ,,lake ,the low isthmus1 about #b miles in breadth1 which connects the ,natewa ,peninsula with the rest of the island1 can be crossed without rising more than #dj or #ej feet above the sea4 ,from the occurrence of upraised reefs in the islets and in the low sea-cliffs of the south coast it may be inferred that at no distant period in the history of ,vanua ,levu this isthmus was submerged4 ,the lake1 which is oblong in form1 is about four-fifths of a mile long and about two-fifths broad4 ,its maximum depth according to the ,admiralty chart is #c fathoms2 but the usual depth in the centre varies1 as ,i found1 between #b and #b fathoms4 ,it communicates with the sea on the south coast by a long narrow passage1 rather over a mile in length1 which for the greater part of its course1 excepting near its seaward mouth1 is only between #be and #cj feet broad4 ,mangroves flourish around the lake and also line the passage2 whilst elevated reef-rock is to be observed on the sides of the passage4 ,mr4 ,horne was informed that corals abound in the lake-waters2 but ,i find no reference to this point in my notes4 ,judging from the density of the effluent water1 the specific gravity of the lake-water is that of the sea4 ,the 8rise and fall10 as noticed below1 is considerably less than in the case of the tides at the coast4 ,near the centre of the lake there is a low islet1 some #dj paces across1 and only raised about a foot above the level of the lake at the time of high-water4 ,it is chiefly made up of coral blocks2 but there are a few fragments of basaltic andesite lying about1 which were probably brought there by natives4 ,this islet is mentioned in ,mrs4 ,smythe's account#hg of the visit made by ,colonel ,smythe to the lake in #ahfj2 and by reason of its little elevation it may be accepted as a rude datum-mark of the relative level of land and sea in this region4 ,from this it would appear that there has been no appreciable change of level in this region for the last forty years4 ,except on the north and north-west sides1 the lake is more or less surrounded by hills reaching up to #djj or #ejj feet1 the passage representing a break in the range4 ,on the ,natewa ,bay side the level of the surface is much lower4 ,the low strip of land that intervenes between the north-west corner of the lake and ,natewa ,bay is about a mile across1 and does not attain a greater elevation than #dj or #ej feet above the sea4 ,on its surface1 fragments of basic volcanic rocks are displayed2 but no reef debris came under my notice4 ,at its north-east side the lake is only separated from ,natewa ,bay by a neck of land #cjj to #djj yards in breadth and about #ajj feet high4 ,it was across this neck that the natives in old times used to drag their large canoes4 ,mr4 ,horne#hh who visited this neighbourhood in #ahgh1 suggested that the ,salt ,lake occupies a crater-cavity4 ,the hills around are of volcanic formation1 and ,i am rather inclined to support this view2 but certainty is scarcely possible now1 on account of the great degradation which the surface has evidently experienced during and since the emergence2 whilst subsequent reef-growth has also to some extent masked the original form of the district4 ,it is noteworthy that a somewhat parallel condition of things is presented a few miles to the west by the circular ,naindi ,bay and the low passage1 not more than #ej feet above the sea1 that partly isolate the ,savu-savu ,peninsula4 ,the peculiar behaviour of the tides in connection with the ,salt ,lake and its passage attracted my attention during two visits to this locality4 ,on the first occasion ,i noticed that between two and three hours after the tide at the coast had commenced to rise there was still a strong flow through the passage from the lake1 and that the current was only reversed in the latter half of the rising tide4 ,during my second visit at the end of ,may1 #ahii1 when ,i was accompanied by ,mr4 ,smallwood1 ,i spent a night in observing the behaviour of the spring tides at a spot below the narrow portion of the passage #fjj or #gjj yards from the opening on the coast4 ,here the breadth was about #ajj feet1 the depth at low-water #e feet1 and the rise of the tide #d feet4 ,the current ran seaward at a velocity varying from #a1ejj to #b1ejj yards per hour2 and it continued to flow in this direction for #b hours after the tide had begun to rise on the coast4 7,in the narrow part of the passage the rate of the current would probably be not over #c knots47 ,it is curious that at the place of measurement the bottom was formed of mud into which the pole sank six feet without striking a hard substratum4 ,the observations on the current were made with a vertical float immersed about #c feet4 ,the point of difficulty in the behaviour of the tides is this4 ,the water is running rapidly out of the lake for nine hours2 whilst during the remaining three hours there is a sluggish return-flow up the passage into the lake4 ,a far greater quantity of water finds an exit by the passage than is returned by the same channel2 and ,i can only explain this by assuming that there is an extensive percolation of water from ,natewa ,bay into the lake4 ,it is easy to show that with such a narrow effluent1 which cannot have a sectional area exceeding #ahj square feet1 the level of the lake would be only lowered #b or #c feet1 if the average velocity during the nine hours was two nautical miles4 ,the great bulk of the water would thus remain unchanged4 ,the ultimate result of such conditions would be a lake of brine4 ,since1 however1 the sea-water of the lake possesses the ordinary density1 it is apparent for this reason only that there is some other means of supply than by the present narrow passage leading to the sea4 ,the mean level of the ,salt ,lake is evidently rather above that of the sea1 perhaps a foot or two2 and the 8rise-and-fall0 is probably very small4 ,,chapter ,,xiv ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,natewa ,,peninsula ,,this remarkable peninsula is connected with the rest of the island by the low-lying ,salt ,lake district1 a narrow isthmus1 described in the preceding chapter1 which one can cross without rising #ej feet above the sea4 ,my acquaintance with this region is far from complete2 but from the following notes a fair general idea of its geological characters may be gathered4 ,by referring to the map it will be seen that there are three groups of mountains4 ,the north-eastern culminates in ,mount ,freeland or ,ngala1 #b1gdj feet2 the southern is formed by the rugged ,waikawa ,range1 #a1edj feet2 whilst the ,lea ,range to the west attains in ,ngalau-levu a height of #a1ifj feet4 ,they are much cut up by the denuding agencies1 and all bear the stamp of an ancient land-surface4 ,though hot springs are not infrequent1 as at ,ndreke-ni-wai1 ,waikatakata1 ,ndevo1 and ,navuni1 no evidence of recent volcanic action came under my notice4 ,submarine deposits occur at intervals on the surface up to elevations of #a1jjj feet and over2 but with the exception of the comparatively recent upheaval or emergence of some #bj or #cj feet1 indicated by the raised reef-masses and foraminiferous tuffs and clays in different parts of the coast1 there is nothing to suggest that these changes did not occur ages since4 ,in the frequent alteration of its andesitic rocks1 and in the occasional occurrence of porphyrites1 we have sufficient indication of the antiquity of this part of the island as far as its volcanic history is concerned4 ,i will commence the description of this peninsula at its western end4 ,the broken elevated district that extends eastward from the ,salt ,lake to ,fawn ,harbour on the south coast1 and to the mouth of the ,ndreke-ni-wai ,river on the north coast1 is divided into two principal masses1 which are connected by a ridge or col about #djj feet above the sea1 which is situated a little east of ,viene4 ,the western portion1 which may be named the ,viene sub-district1 attains a maximum height of #a1jjj feet4 ,the eastern portion reaches in the peak of ,ngalau-levu1 a height of #a1ifj feet1 and may be termed the ,lea sub-district4 ,,the ,,viene ,,sub-,,district4--,the cliffs on the north coast between ,muanaira and a little east of ,viene are mainly formed of basic tuffs1 often calcareous4 ,at a place about #a miles east of ,viene1 these tuffs as exposed in a coast spur display large flat spiral tests of shallow-water foraminifera #d or #e millimetres across4 ,they may be described in this locality as palagonitic calcareous tuff-sandstones1 more or less compacted1 and containing fragments of palagonitised basic rocks4 ,when crossing the col above referred to one finds similar palagonitic calcareous sandstones and clays exposed on its slopes up to its summit 7#djj feet74 ,on the south side1 in the vicinity of ,vunilangi ,inlet1 foraminiferous clays and reef-limestones are displayed at the foot of the slopes2 and the coast between this place and ,tathelevu to the westward is bordered by low cliffs of reef-limestone raised #f to #h feet above the high-water mark and displaying massive corals in their position of growth4 ,near ,tathelevu there occur raised reefs #aj to #ae feet above the sea2 whilst the hills1 #bej to #cjj feet in height1 at the back of this place are composed of fine and coarse tuffs and tuff-sandstones containing little or no lime1 and apparently no organic remains4 ,they are sedimentary tuffs of mixed composition1 made up of fragments of plagioclase1 rhombic and monoclinic pyroxene1 brown hornblende1 portions of semi-vitreous basic andesite1 and palagonitic debris4 ,in the lower levels they are fine textured with a grain of #b to #c mm4 ,in the higher part their grain is #e to #a mm41 and they are more basic in character and come near to the palagonite-tuffs4 ,at an elevation of #bjj feet they form inland cliffs1 #ej feet high1 in which are imbedded blocks1 #b feet across1 of a blackish pyroxene-andesite with a specific gravity of #bgc1 and belonging to the prismatic sub-order of the orthophyric order of the hypersthene-augite andesites4 ,it is remarkable for the pyroxene prisms of the groundmass1 and shows a little interstitial glass4 ,these cliffs are well displayed behind ,navelatha1 about half a mile from ,tathelevu4 ,between this locality and the ,salt ,lake ,passage1 elevated reef-limestones1 forming low cliffs #f to #h feet high1 together with occasional tuff-agglomerates1 occur at the coast4 ,,the ,,lea ,,sub-,,district4--,this region1 which includes the mountain-range of ,ngalau-levu at the back of ,lea1 is limited by ,fawn ,harbour and ,vunilangi ,inlet on the south coast1 and by the ,ndreke-ni-,wai ,river and a point between ,viene and ,lea on the north coast4 ,its structure1 as is shown below1 is very complicated1 acid and basic rocks being associated in a remarkable manner2 whilst over all lie the submarine tuffs4 ,marine and sub-aerial denuding agencies have shaped and re-shaped the surface to such a degree that it is now impossible to restore it in imagination4 ,on the north coast of this sub-district1 about two miles east of ,viene1 is exposed an altered darkish porphyrite displaying large opaque crystals of plagioclase1 #e to #g mm4 long1 the rock-mass being penetrated by fine veins of chalcedonic quartz1 which also traverse the phenocrysts4 ,its specific gravity is #bf2 but on account of the imperfect development of the felspar-lathes and the amount of altered glass in the groundmass1 which also contains a little calcite1 it can be only generally referred to the augite-andesites4 ,a greenish altered foraminiferous tuff showing fine cracks filled with chalcedony composes a spur in this locality4 ,a propylitic or highly altered dolerite is exposed half-way between ,viene and ,lea4 ,as one nears ,lea from the west the lofty spurs of the mountain of ,ngalau-levu reach the coast1 and basic tuffs and agglomerates prevail4 ,the blocks in the agglomerate are composed of a vesicular semi-vitreous hypersthene-augite andesite1 which is assigned to the second prismatic sub-order1 since it carries prismatic pyroxene in the groundmass4 ,the town of ,lea is picturesquely situated on the coast at the foot of the steep mountain-slopes1 being closed in on the east and west by elevated spurs descending to the sea4 ,fragments of jasper and chalcedony occur in the beds of the streams that here drain the precipitous sides of the range4 ,two dykes of dark basic rocks protrude through the beach in ,lea ,bay4 ,they are composed of augite-andesites referred to genus #ac of the augite-class2 but the two rocks belong to different species of that genus4 ,in the one the felspar-lathes are only #jd mm4 in length1 and there is a little altered glass in the groundmass1 the specific gravity being #bfc4 ,in the other the felspar-lathes average #b mm4 in length1 and the rock has a coarser texture1 whilst the specific gravity is #bg4 ,the augite granules are large 7#jc mm471 and there are irregular lacunar spaces filled with calcite and lined by a brown palagonite-like material4 ,i ascended the second highest peak of the ,ngalau-levu mountain1 which rises to a height of #a1fhj feet behind the town of ,lea1 the highest summit lying to the eastward4 ,ngalau-lailai1 which ,i also ascended1 is a lesser peak1 #a1djj feet in height1 situated yet nearer to the town4 ,basic tuffs and agglomerates similar to those exposed in the western spur of the bay occurred all the way up to the bare rocky pinnacles forming the summits4 ,the blocks in the agglomerates are made up of a semi-vitreous augite-andesite1 which is sometimes scoriaceous or amygdaloidal1 and at other times pseudo-vesicular4 ,augite crystals1 #e or #f millimetres in length1 are inclosed in the tuffs which contain palagonitised materials1 but apparently no organic remains4 ,in the spur on the east side of ,lea ,bay occurs a light-coloured altered hornblende andesite4 ,the brown hornblende is mostly represented by black pseudomorphs4 ,such a rock appears in strange contrast with its basic surroundings4 ,this is followed1 as one proceeds eastward along the coast1 by basic tuffs and agglomerates4 ,it should have been before observed that blocks of a blackish-brown olivine basalt 7sp4 gr4 #bhi71 referred to genus #ac of the olivine class1 occur at intervals on the coast between ,viene and ,ndreke2 but the rock never presented itself in position4 ,the tiny felspar-lathes 7#jc mm4 long7 are in flow arrangement2 but there is little or no residual glass1 and the augite granules 7#ja mm47 occur in great abundance4 ,about two-thirds of the way between ,lea and ,ndreke-ni-wai there lie close to the shore two islets1 #bj to #be feet high1 of reef-limestone1 in which massive corals may be observed in their position of growth4 ,further east1 about half a mile west of ,ndreke-ni-wai1 there is exposed at the coast a bedded light-coloured non-calcareous compacted tuff-rock1 dipping #ab to #ae to the southward4 ,it contains pebbles and blocks of acid and basic andesitic rocks1 and may be described as an altered hornblende-andesite tuff4 ,basic agglomerates occur as one approaches ,ndreke-ni-wai4 ,this town lies at the mouth of the river of that name1 the first river that one meets on the north side of this peninsula4 ,there exist here between the tide-marks some hot springs1 to which reference is made on page #cd4 ,when crossing the ,natewa peninsula from ,ndreke-ni-wai to the head of ,fawn ,harbour1 one reaches a height of #ffj feet above the sea4 ,this ridge represents the 8divide0 between the ,lea and ,waikawa mountain-ranges4 ,in the lower part of the northern slopes of this ridge occur basic tuffs and agglomerates2 but between #bjj and #djj feet a light-coloured acid rock of the hornblende-andesite type prevails1 both in the form of agglomerate and of loose blocks4 ,this rock is described under the second order of the hornblende-hypersthene andesites on page #bii4 ,descending the south slope1 ,i found at an elevation of #ejj feet a single large mass1 about #d feet across1 of quite another type of volcanic rock1 which is referred to the orthophyric order of the hypersthene-augite andesites 7page #bij74 ,it is a dark grey almost holo-crystalline rock 7sp4 gr4 #bfi7 showing porphyritic pyroxene to the eye and displaying in its relatively scanty groundmass short stout felspars1 #je mm4 in length4 ,on the surface of the lower two-thirds of this southern slope occur basic tuffs and agglomerates1 basaltic blocks being found in the streams4 ,the tuffs are palagonitic and contain a few calcareous particles4 ,they apparently contain some foraminiferous shells and are doubtless of submarine origin4 ,it would seem that the axis or deeper portion of this ridge is composed of the hornblende and hypersthene-augite andesites1 whilst the basic tuffs and agglomerates form the slopes4 ,with reference to the south side of the ,lea sub-district1 it may be observed that whilst on the north side the mountains rise up close to the sea-border1 here they are separated from the coast by a broad tract of lowland1 where bedded pteropod and foraminiferous clay-rocks are exposed1 dipping gently to the south-east4 ,usually between ,fawn ,harbour and ,vunilangi ,inlet the coast is margined by low cliffs of coral-limestone1 showing the massive corals in position2 but sometimes the deposits above noticed compose the low cliffs and even the islets close by4 ,,the ,,waikawa ,,mountains4--,this range occupies nearly the whole area of the broad and elevated promontory that is only separated from ,taviuni by the narrow straits of ,somo-somo1 which1 however1 have a minimum depth of #abj fathoms4 ,these mountains extend to the vicinity of ,mbutha ,bay on one side and to near ,fawn ,harbour on the other4 ,several of the peaks reach to over #a1jjj feet1 the greatest height given in the ,admiralty chart being #a1edj feet4 ,the whole region has a very rugged aspect1 the mountains rising up near the coast1 whilst the surface is much cut up into ridges and valleys4 ,a single traverse across the range was alone made1 but the results obtained are very suggestive and may doubtless be applied to much of this rugged promontory4 ,i crossed the mountains from ,loa to ,waikawa4 ,the summit was about a mile broad and undulating1 the level varying between #ijj and #a1aej feet4 ,at one place on the top there was a deep hollow1 some #cjj or #djj yards across1 perhaps the remains of an old crater-cavity2 but the higher slopes were so densely wooded that it was not possible to get a clear view of my surroundings4 ,basic tuffs and agglomerates prevailed on either side from the foot to the top of the range4 ,specimens obtained from between #hjj and #ijj feet above the sea are characteristic palagonitic tuffs of varying degrees of coarseness containing #e to #aj per cent4 of carbonate of lime and a few tests of foraminifera4 ,at #a1ajj feet ,i obtained a specimen which on account of the large proportion of carbonate of lime 7#ce per cent47 and the abundance of foraminiferal tests may be termed an impure foraminiferal limestone belonging to the group of these rocks described on page #cai4 ,the tests range up to a millimetre in size1 and there are also inclosed a few large fragments1 #a to #b centimetres in size1 of shells and crystalline limestone4 ,the residue is made of the detritus of semi-vitreous basic rocks1 palagonitic debris1 fine clayey material and minerals 7#ae per cent471 the last including beside plagioclase abundant more or less perfect pyroxene prisms1 mostly of the rhombic type4 ,near the summit there occurred in one place blocks of a highly basic blackish olivine-basalt 7sp4 gr4 #bii71 marking evidently the situation of a dyke4 ,this rock is referred to genus #ac of the olivine-class4 ,it displays abundant phenocrysts of olivine and augite with but little plagioclase4 ,interstitial glass is scanty1 the groundmass consisting of stoutish felspar-lathes 7#jf mm4 long71 abundant augite granules and prisms1 and magnetite4 ,the ,waikawa mountains would thus seem to possess the same general structure that characterises many of the ranges of the island4 ,submarine basic tuffs and agglomerates cover their sides and their summits1 the deeper rocks forming the axis of the range being in this case not so frequently exposed4 ,on the coast between ,waikawa and ,navuni1 rather over a mile east of ,fawn ,harbour1 basic agglomerates1 palagonitic tuff-sandstones1 and calcareous clay-rocks containing pteropod and foraminiferous tests1 prevail4 ,the tuff-sandstones and clay-rocks are bedded1 the stratification being often well shown in the horizontal sections displayed in the shore-flat4 ,in one locality within an area a few hundred yards across1 a quaquaversal dip was exhibited4 ,at ,navuni1 where the hills reach the coast1 the same formations occur4 ,i ascended the stream-course there for about a mile1 basic tuffs and agglomerates being exposed in its sides1 whilst blocks of a heavy dark olivine-basalt#hi lay in the bed4 ,the hot springs which issue inland at the side of this stream are described on page #ce4 ,,the ,,basin ,,of ,,the ,,ndreke-,,ni-,,wai ,,river4--,with the region1 which is bounded on the north by the ,mount ,freeland ,range or the ,ngala mountains and on the south by the ,waikawa ,range1 ,i have but slight acquaintance1 except in the case of the coast fronting ,natewa ,bay4 ,a little way up the course of the river ,ndreke-ni-wai1 which drains this area1 lies the town of ,koro-ni-yasatha1 where ,mr4 ,horne1 the botanist1 spent some days in #ahgh4 ,probably much of this area is not over #bjj feet above the sea1 and apparently there is a good deal of talasinga country4 ,,the ,,coast ,,between ,,the ,,mouth ,,of ,,the ,,ndreke-,,ni-,,wai ,,river ,,and ,,the ,,foot ,,of ,,the ,,ngala ,,or ,,mount ,,freeland ,,range4--,between this estuary and ,valavala1 two miles to the eastward1 occurs a bedded calcareous palagonitic tuff of sedimentary origin1 dipping steeply to the north4 ,in one locality there is a rudely columnar dyke of a porphyritic augite-andesite4 ,coarse basic tuffs exposed in the cliffs and shore-flat of ,ko-nandi-nandi ,point on the side of ,valavala ,bay display a spheroidal structure1 due probably to the vicinity of some igneous intrusion4 ,the sea-border extending from this bay to ,natewa1 and farther on to ,waikatakata1 near the foot of the ,ngala mountains1 is in most parts a broad low strip of coast-land1 where rock-exposures are infrequent4 ,a dark grey andesite forms the blocks of the agglomerate in this locality4 ,it is noticeable on account of the prismatic pyroxene of the groundmass2 and it is assigned to genus #e of the second 7prismatic7 sub-order of the hypersthene-augite andesites4 ,a blackish semi-vitreous pyroxene-andesite occurs in the vicinity of ,natewa4 ,at ,waikatakata 7the ,fijian word for 8hot water071 where an outlying spur of the ,mount ,freeland or ,ngala ,range reaches the coast1 hot springs issue on the hill-side1 as described on page #cd4 ,on the slopes around the springs lie huge masses of an aphanitic basaltic andesite having a specific gravity of #bha and referred to genus #af of the augite sub-class4 ,it displays a characteristic andesitic groundmass1 showing crowded felspar-lathes in flow-arrangement with average length of #ag mm41 and containing scarcely any residual glass4 ,proceeding along the coast east of ,waikatakata1 one enters the region of altered pyroxene-andesites1 for which ,mount ,freeland1 or the ,ngala ,range1 is remarkable4 ,there are first to be observed on the shore blocks of a grey altered ophitic dolerite1 which belongs to the non-porphyritic division of genus #aj of the augite-andesites and is described in detail on page #bge4 ,afterwards the characteristic rocks of the district occur4 ,the lofty spurs of the ,ngala ,range here reach the shore2 and between them lies the coast village of ,ngara-vutu1 from which the ascent to the summit is best made4 ,,mount ,,freeland ,,or ,,the ,,ngala ,,range ,this high range forms a conspicuous object in the profile of this part of the island4 ,it derives its ,fijian name from the old war-town of ,ngala that was situated at an elevation of #a1ejj or #a1fjj feet overlooking ,ngara-vutu on the west4 ,the main mass of the range takes a crescentic sweep1 #c or #d miles in extent and facing ,natewa ,bay4 ,it incloses the coast district of ,tunuloa4 ,the steep mountain-slopes here rise to #b1jjj feet and over1 the greatest elevation being #b1gdj feet4 ,the densely wooded spurs of the range occupy most of the area between the town of ,natewa1 ,kumbulau ,point1 and ,mbutha ,bay4 ,the summit is a long narrow ridge covered with a dense entangled mass of ,freycinetia stems which render progress very difficult4 ,the rocks exposed all the way up from the stream-courses in the vicinity of ,ngara-vutu to the top1 are almost all of the same type1 namely altered augite-andesites4 ,they are dark grey in colour and effervesce slightly with an acid1 whilst occasionally they show a little pyrites4#ij ,agglomerates were not observed and tuffs only in one locality1 #a1bjj feet above the sea1 where a highly altered tuff composed of debris of the prevailing rocks was exposed4 ,at an elevation of #ejj feet there occurred a grey doleritic porphyritic rock1 displaying large opaque crystals of plagioclase1 and looking like a porphyrite4 ,it exhibits a semi-ophitic groundmass1 and is probably an intrusive mass4 ,a description of it will be found under genus #aj of the augite-andesites 7page #bgd74 ,the general petrological characters of the principal summit of ,mount ,ngala point to its high antiquity as a volcanic mountain4 ,it probably ranks among the oldest extinct volcanic vents in the island4 ,proceeding along the coast from ,ngara-vutu to ,navetau1 the ,buli's town of the ,tunuloa district1 one observes blocks of basic rocks4 ,farther to the eastward for a distance of two or three miles basic agglomerates and basic tuff-agglomerates prevail along the sea-border1 being often extensively exposed in the cliff-faces of the hills4 ,the rock composing the blocks is a hemi-crystalline pyroxene-andesite remarkable for the prismatic pyroxene in the groundmass1 and referred to genus #ag of the hypersthene-augite sub-class4 ,i crossed the range to ,ndevo on the other side of the peninsula from a place three or four miles west of ,kumbulau ,point1 rising on the way to a height of #icj feet4 ,for the lower #cjj feet on the north slope basic agglomerates and basic tuff-agglomerates are exposed4 ,they are made up of the same materials as those above described on the coast4 ,near and at the summit occur compacted brecciated tuffs made up of palagonitised basic materials but containing no lime1 and these are associated with light greenish fine-textured hard tuffs of an acid character1 but without lime or organic remains4 ,in this last case the deposit is formed of mineral fragments 7oligoclase1 rhombic and monoclinic pyroxene1 c471 the debris of a hemi-crystalline volcanic rock1 and a quantity of greenish alteration products4 ,on the south side in the vicinity of ,ndevo the sea-border is composed of calcareous palagonitic clays and tuffs containing pteropod shells and large tests of foraminifera in abundance4 ,these deposits1 which are horizontally bedded1 extend a mile inland and reach to between #bej and #cjj feet up the slopes4 ,a hot spring is stated to occur between the tide-marks near ,ndevo4 ,at intervals all along the coast between ,ndevo and ,nuku-ndamu1 passing on the way the villages of ,koro-i-vonu1 ,tuvumila and ,kanakana1 fine and coarse basic tuffs1 often calcareous1 are to be seen exposed in the sea-cliffs and in the low hills behind4 ,they are bedded and dip #e to #aj ,w4,s4,w4 near ,ndevo and #ae to #bj ,s4 b ,w4 south of ,kanakana4 ,the lower slopes of the ,ngala mountains here approach the coast1 and it is highly probable that the submarine tuffs which form the sea-border extend a considerable distance inland and to some height above the sea4 ,between ,nuku-ndamu and ,tukavesi1 where the mountains rise close to the beach1 occur basic agglomerates and agglomerate-tuffs1 derived from basaltic andesites4 ,a specimen of the last named represents an uncommon type of basaltic rock 7sp4 gr4 #bhe71 which on account of the character of the felspars and of the pyroxene of the groundmass is referred to the prismatic sub-order of the orthophyric order of the hypersthene-augite andesites 7page #bij74 ,it may be inferred from the foregoing remarks that whilst the main elevated mass of the ,ngala ,range is composed of altered basic andesites1 the product of ancient eruptions1 the basic agglomerates1 tuffs1 and clays1 which occur on the lower slopes and in the outlying spurs1 are of later date4 ,these tuffs and clays are evidently of submarine origin1 at least in the lower levels2 but although fossiliferous deposits were not observed at greater elevations than #cjj feet above the sea1 it is probable that future investigators will find them at much higher levels4 ,their discovery1 as before noticed1 at an elevation of #a1ajj feet in the adjacent ,waikawa mountains1 renders it likely that as in the case of the mountainous districts of the main portion of the island the whole of the ,natewa peninsula was at one time submerged1 or at least all the region excepting the summit of ,mount ,ngala4 ,,chapter ,,xv ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,north-,,east ,,portion ,,of ,,the ,,island ,,this large area1 which extends for a distance of nearly forty miles from the eastern slopes of the ,mount ,thurston ,range to ,undu ,point1 forms the region closing in ,natewa ,bay on the north4 ,it would be difficult to imagine an area of this size with a greater variety of surface or showing such a lack of arrangement of its principal features4 ,the hills and mountains on the north side gather at the coast1 and extensive inland plains1 raised but a few feet above the sea and strewn with silicified corals1 occupy a portion of its interior4 ,a long valley with a very small gradient extends nearly across its breadth2 and the rivers are for the most part tidal estuaries fed1 except in one or two cases1 by insignificant streams4 ,there is1 however1 a lofty range of ridge-mountains in its broadest part attaining a height of #b1ejj feet2 whilst away to the east stretches the great ,undu ,promontory singular for the straightness of its form4 ,volcanic rocks of acid types1 such as oligoclase-trachytes1 quartz-porphyries1 and white pumice-tuffs prevail in the northern part between ,undu ,point and the promontory opposite ,mali ,island4 ,in the southern part1 from the foot of ,mount ,thurston and ,vuinandi to the vicinity of ,tawaki1 massive rocks and tuffs and agglomerates of basic characters predominate4 ,although my acquaintance with this area is incomplete1 the data below given will be sufficient to enable a general idea to be formed of its structure4 ,the more conspicuous features in its geology will gradually come into prominence as the various localities visited are described4 ,,the ,,southern ,,sea-,,border ,,between ,,vuinandi ,,and ,,the ,,vicinity ,,of ,,tawaki ,the basic rocks1 which characterise this long extent of coast1 give place about two miles west of ,tawaki to the acid rocks4 ,i will proceed methodically with the description from ,vuinandi eastward4 7a7 ,the coast between ,vuinandi and ,nakarambo4--,along this coast1 spurs from the ,mount ,thurston ,range reach the borders of ,natewa ,bay1 forming a succession of small bays a mile or so across1 on the shores of which are situated the villages and towns of ,vuinandi1 ,ndaku-ndaku1 ,korotasere1 and ,nakarambo4 ,the basaltic rocks characteristic of the vicinity of ,vuinandi are predominant here2 but agglomerates and tuffs are of rare occurrence1 the prevailing rocks exposed in the spurs being fine textured basaltic andesites 7sp4 gr4 #bhb74 ,a calcareous tuff-clay is1 however1 to be observed in the east point of ,vuinandi ,bay1 where it is apparently penetrated by a dyke of the above mentioned rock4 ,in ,ndaku-ndaku ,bay there issue from the shore-flat between the tide-marks some hot springs which are referred to on page #cd4 7b7 ,the coast between ,nakarambo and ,waimotu4--,in this tract we meet with rocks of a somewhat different character1 though still basic in their type4 ,through the agglomerates and agglomerate-tuffs of the spurs protrude coarsely crystalline grey pyroxene-andesites4#ia ,they are to some degree altered1 and are characterised by their abundant phenocrysts of plagioclase and of rhombic and monoclinic pyroxene1 the groundmass being relatively scanty4 ,the agglomerates are formed of similar materials4 ,there is an interesting exposure in the point east of ,nakarambo4 ,my specimens from this locality were unfortunately lost2 but in my notes reference is made to the coarsely crystalline grey andesite above noticed1 to the later intrusion of a dark amygdaloidal rock1 and to an altered calcareous tuff4 7c7 ,the coast between ,waimotu and ,natasa ,bay4--,a low belt of land often forms the sea-border4 ,between these two localities there is a broad estuary1 the village of ,vanuavou being situated on the right side and ,malati on the left side4 ,tuffs usually calcareous and probably submarine are here displayed together with basaltic andesites4 7d7 ,the coast between ,natasa ,bay and the vicinity of ,tawaki4--,this extensive stretch of sea-border1 nearly #ae miles in length1 is characterised by hilly spurs and long intervening low-lying tracts4 ,the prevailing rocks exposed are tuff-clays1 somewhat hard and altered1 and coarser basic tuffs sometimes calcareous and overlying the former4 ,these sedimentary deposits1 which are evidently submarine1 are often bedded and have a fairly constant dip over most of this region of #aj to #ae degrees to ,n4,w4 or ,w4,n4,w4 ,they are frequently pierced by dykes1 #f to #aj feet thick1 of compact basic rocks4 ,a specimen of one of these dyke-rocks from between ,natasa and ,vatu-karoa is a doleritic basalt with scanty olivine 7sp4 gr4 #bha7ib2 but the rock of the dykes east of ,vatu-karoa is less basic 7sp4 gr4 #bgb71 and may be described as an augite-andesite#ic with a doleritic structure in part disguised by alteration4 ,between ,natasa and ,sangani there is a remarkable exposure of an intrusive opaque white rhyolitic rock associated with altered tuffs4 ,this rock1 which has undergone some degree of alteration1 is described on page #caa4 ,it is the only indication of the vicinity of a region of acid rocks that ,i came upon on this tract of coast4 ,it probably1 if traced inland1 would be found connected with the district of acid rocks4 ,in following along the coast1 however1 towards ,undu ,point1 the region of acid rocks is not reached until within #b or #c miles west of ,tawaki4 ,reference should be made here to two hot springs that1 as described on page #cc1 rise up on the coast at ,natuvu1 a little east of ,lakemba4 ,,the ,,inland ,,mountainous ,,region ,,between ,,the ,,eastern ,,foot ,,of ,,the ,,mount ,,thurston ,,range ,,and ,,the ,,vicinity ,,of ,,tawaki ,this inland region corresponds for the most part to the tract of coast before described between ,vuinandi and the vicinity of ,tawaki4 ,we have here a very much broken area traversed in a northerly and southerly direction by mountain-ridges and penetrated in places on the north side by prolongations of the ,wainikoro and ,kalikoso plains4 ,the two loftiest summits1 the ,ndoendamu and ,savu-riti peaks of the chart1 rise respectively to heights of #b1dha and #b1bch feet4 ,the former is the ,hale ,peak of the ,wilkes' ,expedition2 but as regards the native names there is some confusion and ,i have not been able to clear it up4 ,several of the lesser peaks rise to over a #a1jjj feet1 and four or five of them to rather over #a1ejj feet4 ,with the exception of the fixing of the positions of the more conspicuous peaks1 the interior of this part of the island is unsurveyed4 ,i was able to lay down my positions approximately2 but before a systematic examination can be made of the geology of this region a survey is necessary4 ,several traverses and ascents were made by me2 but much more in the way of exploration remains to be done4 ,i venture1 however1 to think that from the data below given a fairly accurate notion of some of the leading geological features of this region may be formed4 ,the districts visited will be described in their order from east to west4 7a7 ,the mountainous district east of the mountains of ,vungalei and ,nailotha1 extending to the vicinity of ,tawaki4--,mr4 ,thomson#id in his map of the sea-border of this district shows a continuous coast range from near ,tawaki to ,natasa lying about two miles inland4 ,this is the appearance when the region is seen in profile from a distance2 but when viewed from an elevation in its interior its surface is seen to be for the most part traversed by a series of mountainous and hilly ridges trending roughly north and south1 the greatest height not exceeding #a1ejj or #a1fjj feet4 ,the geological character of the sea-border of this district has already been described on page #bjh4 ,it is there shown that fine and coarse sedimentary tuffs1 sometimes calcareous1 and often penetrated by basic dykes1 here prevail4 ,their general story is one of great denudation1 and we have the same testimony impressed on us when examining one of the inland mountain-ridges4 ,i followed the crest of one of these ridges from the hamlet of ,nawi1 on the headwaters of the ,vui-na-savu ,river1 in a south-easterly direction for about #d miles to the peak of ,uthulanga1 which overlooks ,lakemba on the shore of ,natewa ,bay4 ,during the walk my level rose fairly gradually from that of ,nawi1 less than #ajj feet above the sea1 until near ,lakemba1 where a height of #a1djj feet was attained4 ,here the ridge abruptly terminates in the round-topped peak of ,uthulanga1 which rises steeply from its crest for another #aej feet or rather more1 and has a precipitous face on the southern side descending far down the mountain-slope4 ,this peak1 which is about #a1eej feet above the sea1 when seen from the opposite shores of ,natewa ,bay is very conspicuous and looks like a thumb or a nose4 ,the first part of the ,fijian name of this peak signifies a nose4 ,the hamlet of ,nawi1 from whence the ridge begins1 is built on a low mound-like 8rise10 which is composed of a dark-grey hypersthene-gabbro4 ,since plutonic rocks are of very rare occurrence in this island1 the ,nawi gabbro has a particular interest4 ,it belongs to the group of plutonic rocks described on page #bej2 and is to be referred to the more basic kinds1 its specific gravity being #bhd4 ,in appearance it is like a diallage-gabbro1 and in the slide displays monoclinic and rhombic pyroxene filling the interspaces between the large plagioclase crystals and undergoing respectively the diallage and bronzite stages of schillerisation4 ,this rock forms the type of the group and need not be referred to in more detail here4 ,it should be added that in the bed of the neighbouring river occur blocks of a basaltic andesite 7sp4 gr4 #bhf7 referred to genus #a of the hypersthene-augite andesites4 ,it is a less crystalline form of the gabbro just mentioned4 ,the prevailing rock exposed for the first #b miles on the crest of the ridge 7by starting from ,nawi7 was a greenish porphyrite displaying large opaque crystals of oligoclase1 but showing much alteration of the propylitic kind1 its specific gravity being #be1 but the structure of the groundmass is much disguised4 ,during the next mile1 basic agglomerates and a massive hypersthene-augite andesite were exposed4 ,the last-named is semi-vitreous1 and on account of the prismatic pyroxene of the groundmass is placed in genus #e of its sub-class4 ,its specific gravity is #bg4 ,in the last and fourth mile of the ridge was exposed a dark grey doleritic basalt 7sp4 gr4 #bhe71 which rings like clinkstone under the hammer1 and weathers in a honeycombed fashion4 ,the felspar-lathes average #c mm4 in length1 the residual glass being scanty4 ,the pyroxene phenocrysts include some of rhombic pyroxene2 and the rock is therefore referred to genus #d of the hypersthene-augite andesites4 ,the actual peak of ,uthulanga1 as it rises abruptly about #aej feet from the end of the ridge1 is of agglomerate1 the blocks being composed of a compact grey andesite4 ,the peculiar succession of rocks displayed in this mountain-ridge along its length of four miles is worthy of notice4 ,neither vesicular nor scoriaceous rocks came under observation2 and it is to be assumed that there existed originally a line of submarine vents1 some of them ejecting acid and others basic materials4 ,mainly on account of the great marine erosion during the period of emergence1 but partly also on account of the subsequent sub-aerial denudation1 a plain ridge now represents this line of vents4 ,probably the peak of ,uthulanga1 which is evidently an old volcanic neck1 represents the last of the stages in the volcanic history of this ridge2 but a very long period must have since elapsed4 ,when1 however1 we look at the exposed gabbro at the other end of the ridge1 we have to carry the period much farther back1 since here the superjacent surface volcanic rocks have been stripped off completely4 ,on page #b ,i have referred to an island in the ,solomon ,group where we have such a chain of ancient vents of acid and basic rocks4 ,in that case the forms of the separate hills indicating the original vents are still to be recognised4 ,in this old mountain-ridge of ,vanua ,levu no such outlines remain except in the instance of the terminal peak4 7b7 ,the ,nailotha and ,vungalei ,range4--,this lofty range1 which towers above all around it1 attains a height of #b1dha feet in the peak of ,nailotha and of #b1bch feet in that of ,ndrukau or ,vungalei4 ,the first is1 as ,i infer1 the ,ndoendamu or ,hale ,peak of the charts2 but it is uncertain whether the name ,savu-riti should be applied to the northern peak of the range as it is in the charts1 or whether it belongs to an independent peak farther to the east4 ,by the natives in the vicinity the northern peak is known as ,ndrukau1 and ,i have added the name of ,vungalei from the village at its foot4 ,the southern peak is that of ,nailotha4 ,the range runs roughly north and south4 ,it is1 however1 obvious that the internal topography of this part of the island is but scantily known4 ,brief reference will first be made to the country bordering the range on the north-west and west sides in the vicinity of the villages of ,vungalei and ,tembe4 ,in proceeding south from ,kalikoso1 which lies in the midst of the low-lying ,wainikoro plains1 to ,vungale one traverses this level district1 of which the elevation is never more than #aej feet above the sea and often much less4 ,about a mile south-east of ,kalikoso the limit of the region of quartz-porphyries and of acid tuffs is passed and the area of basic rocks is entered1 a dark semi-vitreous pyroxene-andesite with a flinty fracture prevailing at the surface as far as ,vungalei4 ,this rock displays a few small phenocrysts of oligoclase and pyroxenes in a blurred glassy groundmass exhibiting the felspar and pyroxene microliths in process of development 7sp4 gr4 #bdf74 ,vungalei itself is only elevated about #acj feet above the sea4 ,in proceeding from this village to ,tembe1 lying about two miles ,s4,s4,w41 one crosses a line of hills1 about #fjj feet in height1 which form a spur of the main range4 ,basic agglomerates similar to those found on the slopes of ,mount ,vungalei1 as described below1 prevail in the district between these two villages up to the top of the intervening hills4 ,in places one notices that they overlie the ordinary sedimentary deposit1 known as 8soapstone10 a slightly calcareous clay-tuff but showing no organic remains to the eye4 ,the rock exposed in the stream-courses is a semi-ophitic basaltic andesite 7sp4 gr4 #bgd7 which contains a considerable amount of interstitial glass4#ie ,when proceeding ,s4,s4,w4 from ,tembe on the way to ,nandongo one passes on either hand1 as described on page #baf1 hills about #gjj feet high displaying vertical cliffs formed of agglomerates over-lying finer sedimentary beds apparently of the 8soapstone0 character4 ,i made the ascent of ,mount ,vungalei from the village of that name4 ,the peak is also known as ,ndrukau4 ,basic agglomerates were exposed all the way up to an elevation of about #b1jjj feet1 where a bed of a somewhat scoriaceous basaltic andesite was displayed1 the upper #bjj feet being inaccessible but of the same agglomerate4 ,at a height of #cjj feet was observed another layer of the same basaltic rock4 ,these intercalated beds appeared to be lava-flows rather than horizontal dykes4 ,the agglomerates become less coarse in the upper part of the mountain where they take the character of agglomerate-tuffs4 ,the blocks are composed1 like those in many other parts of the island1 of a dark semi-vitreous basaltic andesite1 but often scoriaceous4 ,but the most remarkable features of these agglomerates are the indications of two distinct pauses in their deposition afforded by the occurrence at elevations of #ijj and #a1gjj feet of a single horizontal bed1 two to three feet thick1 of coarse palagonite-tuffs4 ,each bed is exposed at the foot of a tall cliff of agglomerate forming a line of escarpment along the mountain-side4 ,the larger fragments making up these tuffs are usually from #b to #c millimetres in size2 but the process of palagonitisation is not complete2 and we find inclosed abundant angular pieces of a dark fresh tachylyte-glass1 finely vesicular1 and fusing readily in the ordinary spirit-lamp flame4 ,the tuffs contain little or no lime and seemingly no organic remains4 ,in the lowest bed ,i noticed a little water-worn gravel4 ,both beds pass gradually into the underlying agglomerate2 but their upper limits are well defined and the agglomerate commences abruptly4 ,it is thus seen that in the formation of the agglomerates there were two pauses when they gradually gave place to deposits of fine detritus made up of a vesicular basic glass that has since been largely converted into palagonite4 ,then followed a sudden renewal of the agglomerate-producing process4 ,we can scarcely doubt that the agglomerates1 with their scoriaceous blocks1 and the palagonite-tuffs are in the main the direct products of volcanic eruptions4 ,the rival claim of marine denudation as the agency concerned can be mostly but not altogether excluded4 ,the agglomerates and tuffs of ,mount ,vungalei cannot be distinguished from those so often described in the case of the great inland ranges of the other parts of the island1 the submarine origin of which is frequently demonstrated by the inclosed organic remains4 ,it would seem that in the instance of ,vungalei these deposits took place around the shores of a volcanic mountain that rose above the sea4 ,on page #cae it is pointed out that in ,stromboli with its dribbling eruptions we have a good illustration of the manner in which such deposits could be formed4 ,my examination of the mountain of ,nailotha was restricted to the lower slopes up to an elevation of #fjj feet2 but the results obtained are very suggestive4 ,when following up the stream-course on the way from ,tembe to the mountain one notices in its bed blocks of a light-coloured rock like a compact quartzite4 ,it is1 however1 a highly altered oligoclase-trachyte 7sp4 gr4 #bec7 with its structure much disguised by secondary quartz4 ,this is the first intimation one gets1 on leaving behind the district of basic agglomerates about ,tembe1 of the otherwise unexpected character of the acid rocks displayed in the lower part of ,nailotha4#if ,a torrent here cuts deeply into the mountain-side4 ,at the base1 between #bjj and #cjj feet above the sea1 a bluish-grey rather scoriaceous rock with the steam-pores drawn out to a length of from #a to #b centimetres1 is first exposed4 ,its specific gravity after allowing for the cavities is less than #bf4 ,it shows a groundmass partly disguised by secondary quartz and containing numerous small vesicles lined by quartz and filled with viridite and epidote4 ,where the alteration is less advanced small parallel felspar-lathes with fine decomposing pyroxenes are shown4 ,the lathes give extinctions of two or three degrees and average #jd mm4 in length4 ,in its somewhat scoriaceous nature1 in the absence of phenocrysts1 and in its less altered condition1 this rock differs from those exposed higher up the ravine2 but it is evidently to be referred to the same acid type4 ,at a height of #cjj feet a light grey highly altered oligoclase-trachyte 7sp4 gr4 #bdc7 is exhibited4 ,it contained originally some phenocrysts of felspar and pyroxene1 which1 however1 have been more or less replaced by calcite1 quartz1 and other materials2 whilst the groundmass1 originally hemi-crystalline but now blurred by the deposition of silica1 shows felspar-lathes in process of development4 ,a little farther up the gorge there is displayed another highly altered rock with a siliceous appearance1 such as has been noticed above as forming blocks in the stream near the foot of the mountain4 ,it is an oligoclase-trachyte impregnated with crystalline silica and exhibiting a singular prismatic structure1 the small columns or prisms being only #c or #d inches in diameter4 ,between #djj and #ejj feet occurs a light-coloured compact rock sparkling with pyrites and also displaying a columnar structure1 the columns being between #d and #f inches across4 ,it looks like a limestone and effervesces freely with an acid2 but it is in fact a highly altered oligoclase-trachyte 7sp4 gr4 #be7 of the propylite type4 ,it seems originally to have inclosed a few phenocrysts of oligoclase1 sanidine1 and pyroxene1 and here and there a stout felspar-lathe is to be noticed in the groundmass giving straight extinction4 ,the whole texture of the rock1 however1 is more or less impregnated with secondary quartz1 calcite1 chlorite1 viridite1 pyrites1 c4 ,farther up the ravine1 between #ejj and #fjj feet in elevation1 is displayed a remarkable quartz-porphyry which exhibits opaque porphyritic crystals of felspar as well as rounded crystals of quartz in a grey compact base4 ,it has been subjected to considerable alteration and will be found described on page #caj4 ,at #fjj feet large slabs of the ordinary sedimentary clay-tuffs1 containing but little lime and showing no organic remains to the eye1 lay about on the more level slopes1 and evidently formed a surface deposit incrusting the altered massive rocks4 ,if my ascent had lain up the mountain-side away from the stream-courses1 these sedimentary rocks would alone have been observed4 ,in the gorge1 however1 is exposed to view the deeper-seated rocks that make up the mountain's mass4 ,we have here a thickness of about #djj feet of altered acid rocks4 ,all are doubtless intrusive1 and were subjected to alteration after the development of the columnar structure and before the deposition of the overlying clay-tuffs or 8soapstones10 which are no doubt of submarine origin4 ,these sedimentary tuffs belong probably to the period when the submarine agglomerates and palagonite-tuffs of the neighbouring peak of ,vungalei were formed4 7c7 ,traverse of the coast range from ,nandongo to ,vanuavou on the shore of ,natewa ,bay4--,this route was taken by ,mr4 ,horne1 the botanist1 in #ahgh4 ,i approached ,nandongo from ,tembe to the northward4 ,the road at first lay between hills about #gjj feet in height displaying in their precipitous faces agglomerates overlying fine sedimentary tuffs4 ,these deposits in the form of slightly calcareous basic tuff-clays1 the so-called 8soapstones10 are exposed in the bed of the ,wainikoro ,river as one nears ,nandongo4 ,this village1 which is situated on the headwaters of the ,wainikoro at an elevation of about #ahj feet above the sea1 lies near the foot of the range4 ,in its vicinity there is a small thermal spring which is referred to on page #cc4 ,proceeding south from ,nandongo one notices in the stream-course at the foot of the slopes the sedimentary tuff deposits above mentioned1 bedding and dipping gently to the west4 ,farther up the slopes1 higher than #bej feet above the sea1 there are exposed the deeper-seated rocks of the range in the shape of compact reddish rocks 7sp4 gr4 #bdh71 which appear under the microscope to be highly altered acid andesites or oligoclase-trachytes originally displaying flow-structure and a fair amount of glass1 but now much disguised by the formation of secondary quartz4 ,on this north slope of the range ,i also found an amygdaloidal variety of the same altered rocks containing irregular amygdules1 #e or #f millimetres long1 of fibrous quartz or chalcedony4 ,blocks of basaltic andesite were observed on the summit1 which has an elevation of #iej to #a1jjj feet4 ,on the southern slopes descending towards ,natewa ,bay coarse basic tuffs together with blocks of basaltic andesite are chiefly exposed4 ,the last-named probably represent dykes both on the south slope and on the summit4 ,the rocks exhibited on the portion of the coast of ,natewa ,bay corresponding to this range are dark and light-coloured sedimentary tuffs usually calcareous1 with occasional basaltic andesites indicating dykes4444 ,from this traverse it would appear that the range has an axis of altered acid rocks overlain by basic sedimentary tuffs and pierced by basaltic dykes4 7d7 ,the mountainous district lying between the head waters of the ,wainikoro ,river and the ,mount ,thurston ,range4--,of this region ,i know very little4 ,the highest peak according to the chart has an elevation of about #a1fjj feet4 ,some indication of the character of the inland rocks may be obtained from that of those exposed on the coast between ,nakarambo and ,waimotu where1 as observed on page #bjh1 grey pyroxene-andesites1 coarse in texture and almost holo-crystalline in structure1 protrude through agglomerates of the same materials4 ,when on the way from ,ngelemumu to ,wainikoro ,i crossed the extreme northern prolongation of this range where the elevation above the sea is only #gjj feet4 ,non-calcareous basic tuff-clays occur on the slopes2 but the deeper-seated rocks1 judging from an exposure on the east side1 are dark grey altered pyroxene-andesites penetrated by fine cracks filled with a mosaic of quartz and having a specific gravity of #bg4 ,on the summit ,i found a gritty sandstone-like rock1 of which my specimen has been lost4 ,in a stream at the foot of the east slope occur small blocks of basaltic andesite probably derived from a dyke4 ,the region of acid rocks1 such as quartz-porphyries1 oligoclase-trachytes1 c41 is not entered until about two miles south-west of ,wainikoro4 ,,the ,,coast ,,ranges ,,and ,,sea-,,border ,,between ,,mbuthai-,,sau ,,and ,,thawaro ,,or ,,mbekana ,,bay ,we have in this region the mountains and hills at the coast and the low-lying plains inland4 ,this feature of the north side of ,vanua ,levu is very remarkable4 ,for some sixty miles1 that is to say1 for more than half the length of the island1 between the mouth of the river ,ndreketi and ,thawaro or ,mbekana ,bay1 ,vanua ,levu possesses this character4 ,the coast ranges west of ,lambasa1 where basic rocks evidently prevail1 have been referred to on pages #ace1 #acf4 ,those east of the ,lambasa mountains as far as ,thawaro ,bay will be dealt with here2 and instead of basic we find acid rocks1 such as quartz-porphyries akin to the rhyolites1 oligoclase-trachytes1 pumice-tuffs1 c4 ,the sea-border is here characterised not by a continuous range running parallel to the coast1 as in the case of the district between ,nanduri and the ,ndreketi ,river1 but by a number of separate groups of hills and lesser mountains1 separated by deep gaps or valleys which are occupied by tidal rivers and extensive mangrove swamps4 ,the tide ascends these rivers into the plains behind the coast ranges1 so that a depression of only #cj feet would convert these groups of hills into separate islands and would cover much of the inland plains with the sea4 ,the hills attain an elevation of #a1bjj or #a1cjj feet a mile or two inland and descend often as bold promontories to the coast4 ,i will refer in order to the different parts of this sea-border4 7#a7 ,,the ,,sea-,,border ,,between ,,lambasa ,,and ,,mbuthai-,,sau ,in the sea-border between ,lambasa and ,mbuthai-sau we have the junction of the regions of basic and acid rocks1 the former extending westward to ,naivaka1 the latter reaching to ,undu ,point4 ,in such a locality the two types of rocks might be expected to be associated1 and this is what occurs4 ,acid pumice-tuffs and basic agglomerates1 sometimes associated1 are here displayed4 ,in the low hills between ,lambasa and ,vuni-ika ,bay1 which lies west of ,mbuthai-sau1 ,i found basic agglomerates prevailing1 together with some acid pumice-tuffs4 ,the blocks in the agglomerates are composed of a blackish semi-vitreous pyroxene-andesite 7sp4 gr4 #bfh71 which is characterised by prismatic pyroxene in the groundmass1 and is referred to genus #f of the second sub-order of the hypersthene-augite andesites described on page #bhg4 ,east of ,vuni-ika on the way to ,mbuthai-sau1 at an elevation of about #ej feet above the sea1 dark tuffs containing small fragments of reef-limestone are exposed in a cutting4 ,a little farther on there is a considerable deposit of a pale grey rhyolitic pumice-tuff1 a soft stone easily worked1 and indeed now quarried by the plantation authorities4 ,it contains no lime and in microscopical characters is scarcely distinguishable from a sample of fine pumice debris collected by me in the ,chirica district of ,lipari ,island4 ,it is made of fragments up to a centimetre in size1 of ordinary fibrillar pumice in a matrix of much finer material of the same nature4 ,portions of crystals of glassy felspar 7oligoclase and sanidine7 also occur in it1 together with some quartz and rhombic pyroxene4 ,the association in this locality of acid and basic eruptive products was observed by ,dana in #ahdj in the cliffs of 8,mali ,point40#ig ,it is not quite clear whether ,mali ,island1 which lies immediately adjacent to the coast1 is here alluded to1 or whether it is a headland opposite to it4 ,dana describes the deposits displayed in these cliffs as coarse aggregates of fragments of pumice and decomposing trachyte1 which pass on the one side into fine clayey material1 and on the other into an agglomerate formed of angular blocks of vesicular and compact basalt with the interstices filled with pale yellow tufaceous material4 ,east of the ,avuka ,range that limits the ,lambasa plains on this side is the picturesque valley of ,mbuthai-sau4 ,this broad valley runs in a south-east direction into the heart of the island4 ,so small is the gradient that the river flowing down it can be ascended in boats for some miles2 whilst ,ngele-mumu1 a village situated between #e and #f miles up the valley1 is not much over #ej feet above the sea4 ,this valley in its lower part roughly divides the regions of acid and basic rocks that lie east and west of it respectively4 ,it has1 however1 been above pointed out that the two regions overlap in the coast region on the west side of the valley4 ,the two types of rocks are also associated in the coast hills immediately east of the valley1 since when striking inland from ,lloyd ,point to the ,mbuthai-sau sugar-cane district1 one leaves behind the acid rocks at the coast and traverses a region of basic agglomerates4 ,with these qualifications1 therefore1 the above line of demarcation holds good4 7#b7 ,,the ,,sea-,,border ,,between ,,the ,,mbuthai-,,sau ,,and ,,the ,,langa-,,langa ,,rivers ,the rocks predominating in this district are white and pale-yellow pumice-tuffs and pumice agglomerates1 with quartz-porphyries and oligoclase-trachytes as intrusive masses4 ,the light colour of the sea-cliffs1 thus composed1 makes them conspicuous from seaward4 ,their appearance evidently led ,mr4 ,horne into an error in #ahgh when he viewed this coast from his canoe during his sea-passage from ,lambasa to ,tutu4 8,the coast from ,lambasa0--he says--8is a series of bold projecting bluffs of agglomerate interspersed with seams of coralline sandstone40#ih ,the principal feature of this coast1 however1 is the prevalence of light-coloured pumice-tuffs1 though it is not improbable that elevated reef-formations may occur in some localities4 ,i particularly examined the coast districts in the vicinity of the ,wainikoro and ,langa-,langa rivers4 ,in a spur that descends to the right bank of the river1 a little above the mouth of the ,wainikoro1 is exposed an open-textured rhyolite or quartz-porphyry containing1 as described on page #caj1 phenocrysts of glassy felspar 7oligoclase and sanidine71 quartz1 and a little hornblende4 ,some interesting exposures occur on the coasts between ,narikosa ,point 7,nari-,roso ,point of the chart7 and the mouth of the ,wainikoro4 ,here the pumice-tuffs and agglomerates are pierced by dykes1 some of them vertical and #f feet across and composed of a light-grey rhyolitic rock1 similar except in its compact texture to the rock above mentioned4#ii ,the small quartz crystals1 which are #a to #b millimetres in size1 are sometimes bipyramidal4 ,many of them are rounded and have a fused-like surface4 ,the pumice-tuff1 which displays no effervescence with an acid1 is composed mainly of finely pulverised vacuolar and fibrillar istropic colourless glass1 and contains also small fragments of glassy felspar and small rounded quartz crystals1 such as occur in the rock forming the dykes in these deposits4 ,imbedded in the tuffs in places are small masses1 up to #d inches in size1 of a pretty grey vesicular rhyolite-glass exhibiting the intermediate condition between compact obsidian and pumice which is so characteristic of the rocks of ,vulcano in the ,lipari ,islands4 ,a more detailed account of this rock is given on page #caa4 ,in the pumice-agglomerates of this locality occur pale-yellow decayed and altered pumice blocks4 ,the headland1 known as ,narikosa ,point1 which lies between the mouths of the ,wainikoro and ,langa-langa rivers1 terminates in a rocky spur formed by a large intrusive mass or dyke of a reddish oligoclase-trachyte altered in character and displaying in places a rudely columnar structure4#ajj ,the pumice-tuffs and agglomerates are well exposed at the coast between ,narikosa ,point and the ,langa-langa ,river4 ,in the vicinity of ,songombiau1 a village here situated1 the tuffs are penetrated by dykes4 ,one dyke at the back of the village is #d or #e feet thick and has vitreous margins4 ,it is composed of a darkish pyroxene-andesite which in the interior of the intrusion in hemi-crystalline and a little vesicular1 but in the margins it is more glassy and rather scoriaceous4#aja ,though not a basic rock in itself1 its specific gravity in the compact state being only about #bee1 it is relatively basic when contrasted with the rhyolitic and trachytic rocks of the district1 which have when compact a specific gravity of not over #bc4 ,pumice-tuffs and agglomerates appear in the cliff-faces of the hills on either side of the lower course of the ,langa-langa ,river from the vicinity of ,kalikoso to the sea4 ,at one place about #c miles up the river a dyke of trachyte1 much altered and showing columns #ab to #ah inches across1 was exposed at the bank4 7#c7 ,,sea-,,border ,,between ,,the ,,langa-,,langa ,,river ,,and ,,thawaro ,,bay ,the next part of the coast which ,i visited was that opposite ,tutu ,island4 ,here a range of high hills1 #a1ajj or #a1bjj feet in height1 sends a lofty spur to the sea1 in the precipitous faces of which are exposed breccia-tuffs and agglomerates derived from acid rocks4 ,a specimen of the tuffs shows1 besides fragments of altered rhyolitic or trachytic rocks1 portions of decomposing pumice1 the vacuoles and tubular cavities of which are filled with alteration products4 ,the blocks in the agglomerates are altered oligoclase-trachytes1 both compact and vesicular4 ,these deposits are non-calcareous and rarely display bedding2 but in one place there was a rude arrangement of the materials1 the dip being to the north-west4 ,i crossed this coast range where it is only #fjj feet above the sea1 and descended into the ,kalikoso plains in the vicinity of ,numbu4 ,in the coast district between ,tutu ,island and the village of ,naua1 #c miles to the east1 the same altered coarse pumiceous and trachytic tuffs1 occasionally bedded and dipping ,w4,n4,w41 form the low hills near the sea4 ,in one place1 where the elevation was less than #bjj feet1 ,i noticed on the surface small fragments of branching corals4 ,they had perhaps weathered out of the tuffs1 and though in part silicified still effervesced freely in an acid4 ,between ,naua and the town of ,visongo occur low hills formed of acid tuffs4 ,at an elevation of #bjj feet the tuffs display a remarkable character4 ,when examined with the lens they are seen to be crowded with the minute tests of foraminifera of the 8,globigerina0 type4 ,the deposit forms a fairly hard light-grey clay-rock which according to the usual acid-test has no lime4 ,under the microscope it is seen to be composed nearly in equal proportion of the tests of foraminifera and of very fine detritus apparently derived from acid rocks1 the materials being generally not over #ja mm4 in diameter1 though some of the felspar fragments measure #je mm4 across4 ,a secondary process of silicification1 as exhibited in the occurrence of minutely granular quartz1 has affected the matrix of the clay as well as the tests of the foraminifera4 ,the deposit is of deep-water origin and appears to have been formed from the fine washings of a coast some distance away4 ,it is noteworthy that the surface in this locality is in places strewn with quantities of angular fragments and round pebbles of chalcedonic flint1 together with large nodules which when broken across are found to be occupied by radiating crystals of quartz and were doubtless formed in the cavities of some rock4 ,reference has already been made to the partially silicified coral fragments lying on the surface of the low coast hills a few miles to the west of this locality4 ,they indicate a relatively recent emergence and we get the same indication from the flints on the surface of this district4 ,these evidences1 however1 relate only to the last stage of the emergence4 ,the testimony of the silicified 8,globigerina0 clay carries us back to the earlier periods of these changes of level1 and probably dates back to a time when the greater part of this portion of the island was submerged1 with the exception of the mountain peaks4 ,not the least interesting feature of the emergence is the silicifying process that accompanied it4 ,this is illustrated on a much greater scale in the neighbouring inland plains of ,kalikoso and ,wainikoro which are described in ,chapter ,,xxv4 ,proceeding eastward from ,visongo to ,namukalau one traverses a coast district not elevated more than #cjj feet above the sea4 ,here there are displayed whitish and pale yellow compacted tuffs differing in aspect from those prevailing to the westward and often bedded1 the dip being about #bj ,n4,w4 or ,n4,n4,w4 ,they show no lime and apparently inclose no organic remains4 ,where the upper surface of a bed is bared1 it shows regular shrinkage-lines inclosing hexagonal spaces #b to #c inches across2 but there is no corresponding columnar structure in the bed-mass4 ,the rock is very light in weight and homogeneous in texture and looks a little like ,china-clay4 ,in a section its structure appears obscure2 but it seems to be formed of the finest detritus1 derived from some acid partly devitrified glass1 the pumiceous structure being in places faintly indicated2 but the whole mass appears to have been subjected to a process of alteration perhaps similar to the ultimate palagonitic change in basic rocks4 ,in the slide a few small felspar fragments1 about #a mm4 in size1 are displayed4 ,just east of ,namukalau is the mouth of the ,vui-na-savu ,river1 the ,na ,savu ,river of the chart4 ,this is a tidal river1 and is navigable for boats for several miles4 ,in the lower part of its course agglomerates and tuffs prevail1 probably in part at least derived from acid rocks4 ,near ,rauriko1 which lies about #e miles up the river1 a bare bluff1 overlooking the valley on the east1 is formed of a decomposed trachytic rock remarkable for the fact that it displays1 as described on page #cgj1 faint magnetic polarity4 ,above ,vitina1 a mile or two farther up1 ,i found a similar rock but amygdaloidal in character4 ,on the head-waters of the river is situated the hamlet of ,nawi1 where1 as mentioned on page #baa1 a plutonic rock of the gabbro type occurs4 ,tuffs and agglomerates appear to prevail in the low coast tract between the ,vui-na-,savu river and ,thawaro ,bay4 99 99 99 99 99 ,in drawing some general inferences respecting the acid formations1 mostly fragmental in character1 that are displayed in the sea-border between ,lambasa and ,thawaro ,bay1 it is necessary to distinguish between the deposits west and east of the ,langa-langa ,river4 ,between ,lambasa and the river just named the tuffs may usually be regarded as the products of sub-aerial eruptions4 ,some of the specimens might have been obtained1 as far as their characters go1 from the pumice-districts in the island of ,lipari4 ,their limeless condition and the apparent absence of organic remains are noteworthy features1 though of course the products of sub-aerial eruptions may be deposited under the sea4 ,it is1 however1 remarkable that no compact obsidian came under my notice4 ,the fragments of rhyolitic glass1 intermediate in structure between compact obsidian and pumice1 that were imbedded in the pumice-tuffs in one locality1 were probably ejected from some sub-aerial vent4 ,in the region between the ,langa-langa ,river and ,thawaro ,bay acid tuffs and agglomerates prevail2 but they have all been subjected to alteration by the deposition of secondary silica1 and the pumice-structure when present is largely disguised4 ,they have evidently1 in part at least1 been derived from compact rhyolitic and trachytic rocks1 and are probably in some measure the products of marine erosion4 ,although neither lime nor organic remains were detected1 the presence of the altered 8,globigerina0 clay near ,visongo is very suggestive and indicates a considerable submergence of this region at some distant period4 ,much1 however1 remains to be done in the examination of the peaks of the coast ranges of this part of ,vanua ,levu2 and it is likely that some interesting results will be obtained from such an exploration4 ,,chapter ,,xvi ,,description ,,of ,,the ,,geological ,,and ,,general ,,physical ,,features 7continued7 ,,the ,,north-,,east ,,portion ,,of ,,the ,,island 7continued7 ,,the ,,wainikoro ,,and ,,kalikoso ,,plains ,,these extensive inland plains occupy a considerable area in this part of the island4 ,i estimate that there is an area of about #bj square miles that does not exceed an elevation of #ajj feet above the sea and is often much less4 ,of the two villages situated in the midst of these plains1 about #e miles inland1 ,kalikoso is about #cj feet and ,wainikoro is scarcely #bj feet above the sea2 whilst much of the surrounding district is similarly low4 ,taking the #cjj-;feet contour-line as a guide1 this low-lying region1 as shown in the map1 would be much larger4 ,the plains are backed on the south by the high mountain-range of ,vungalei and ,nailotha4 ,on the north the coast-ranges1 which attain a height of #a1ajj or #a1bjj feet1 separate them from the sea-border2 whilst on the west they are shut off from the ,mbuthai-sau valley by a line of hills1 of which the minimum elevation is about #gjj feet4 ,this region is occupied by the scanty open vegetation characteristic of the 8talasinga0 or 8sun-burnt0 districts4 ,the tall 8,ngasau0 reed is common2 the ,pandanus trees are frequent2 and amongst the bushes and small trees are represented 8,dodona viscosa10 8,morinda citrifolia10 and a species of 8,hibbertia40 ,different rivers and streams1 rising in the mountains on the south side of the plains1 traverse this area2 and after breaking through the coast-ranges reach the sea4 ,they acquire an exaggerated size from the circumstance that they are in great part tidal estuaries4 ,the tide ascends them for several miles reaching behind the coast-ranges into the plains2 whilst the dense mangroves1 which line their lower courses amongst the hills1 extend beyond into the low-lying level districts farther inland4 ,boats can follow up the winding course of the ,wainikoro ,river until they reach the village of that name1 which lies about five and a half miles in a direct line from the coast and nearly in the centre of this part of the island4 ,the mangroves extend up to the village4 ,the ,langa-langa ,river1 which is of much smaller size1 is similarly navigable for three or four miles4 ,the mangroves that line its banks spread out in broad tracts when in ascending the river we emerge from the hills into the plains4 ,above the influence of the tide it dwindles into a stream ridiculously small4 ,the same remarks apply to the river two miles to the eastward4 ,the ,vui-na-savu ,river near the eastern margin of this low-lying region can be ascended by boats into the heart of the island4 ,from the foregoing remarks it will be expected that some portion of this low-lying inland region will be occupied by swamps4 ,this is in truth the case4 ,about one and a half miles north-east from the village of ,kalikoso is a small fresh-water lake1 about #ajj yards across1 which lies in a slight depression in the plains and is surrounded by a wide margin of swampy ground1 occupied by reeds and sedges1 in which one sinks knee-deep when approaching the banks4 ,the level of the surface of the lake is not over #be feet above the sea1 and only a foot or so below that of the plains around4 ,since the depth1 as ,i ascertained it1 is #ae to #ah feet1 it follows that the bottom of the lake is only a few feet above the high-tide level4 ,the mangroves extend to within a mile of its border2 and it is possible that though lying about five miles inland1 it may be indirectly affected by unusually high tides4 ,it would be interesting to determine whether the water is ever brackish4 ,this small lake is1 or was1 regarded with superstitious awe by the natives on account of the floating islands that it contains4 ,different legends are connected with it1 and the ,fijians have given it the name of 8,vaka-lalatha10 in allusion to the drifting of the islands from one side of the lake to the other1 the small trees growing upon them acting 8in the manner of sails40 ,mr4 ,horne1 who was in this locality in #ahgh1 refers to the lake in his book1 ,a ,year in ,fiji 7p4 #bd72 but does not appear to have seen it4 ,mr4 ,thomson#ajb visited it in #ahhj1 and describes it as containing a single floating island1 a quarter to a half an acre in extent4 ,the island was in existence1 the natives said1 in the days of their great-grandfathers1 a statement indicating that the people of the district had no reason to doubt its antiquity4 ,a chief1 who formed one of the party1 dived under the island4 ,when ,i visited this lake in #ahii there were three floating islands1 named by the natives 8,wanga levu0 and 8,wanga lailai10 that is1 8,large canoe0 and 8,small canoe40 ,the largest was #ij or #ajj feet long1 whilst the two smaller were about #ej feet long1 the breadth being less than half the length4 ,they are composed of a dense growth of reeds and sedges supporting small living trees #aj to #ag feet in height1 swamp ferns1 and other smaller vegetation1 the whole forming fairly solid standing-ground1 and doubtless possessing considerable thickness4 ,the origin of these floating islands is probably to be found in the circumstance that the dense mass of swamp-vegetation lies on a rocky substratum1 and that during some unusually heavy flood large portions of the swampy soil-cap became detached and floated up4 ,a floating island occurs near the sea in the ,lauthala district on the ,lower ,rewa in ,viti ,levu4 ,the floating island in ,derwentwater in the north of ,england is said to be 8a blister of sublacustrine turf40 ,those in ,russia and ,hungary1 according to ,mr4 ,hanusz1 appear to be felted masses of tree-trunks1 branches1 and marsh-plants thinly covered with soil4#ajc ,i will preface my remarks on the geology of the ,wainikoro and ,kalikoso plains by observing that this region displays three conspicuous features4 ,in the first place1 it is a region of acid rocks1 mostly altered tuffs1 derived from quartz-porphyries1 the alteration consisting in the deposition of quartz often of the chalcedonic type4 ,in the second place1 a silicifying process has been in operation here on an extensive scale1 as evidenced by the abundance of silicified corals lying on the surface1 especially in the district around the lake and by the abundance of concretions of chalcedony1 of fragments of chalcedonic flints1 and of portions of white chalcedonic quartz-rock that in places strew the ground4 ,in the third place1 earthy limonite1 or bog iron ore1 has been produced in quantity1 particularly around the lake2 and in places small round concretions of impure carbonate of iron cover the soil4 ,before referring more in detail to the different parts of this region1 it may be remarked that the silicified corals1 flints1 iron-ore deposits1 c41 of this and other parts of the island are dealt with in ,chapter ,,xxv4 ,this region of acid rocks extends about two miles to the west and south-west of the village of ,wainikoro4 ,here prevail white acid tuffs often decomposing and altered by the formation of secondary quartz4 ,they are derived from the degradation of quartz-porphyries or rhyolitic rocks4 ,the surface is irregular but the elevation is small1 the #ajj-;feet level lying about one mile and the #bjj-;feet level about two miles west of ,wainikoro4 ,the villages of ,wainikoro and ,kalikoso are from two to three miles apart1 the intervening district not attaining a greater elevation than #gj feet above the sea4 ,decomposing altered white acid tuffs here occur with occasional large blocks1 a couple of tons in weight1 of apparently a quartz-porphyry or trachyte with its structure disguised by silicification4 ,fragments of siliceous concretions1 as chalcedony1 chalcedonic flints1 c41 lie on the surface1 the soil being friable and of a deep ochreous red2 whilst in places the ground is covered with round marble-sized concretions composed of a mixture of carbonate of iron and limonite which ,i have described on page #cef4 ,a few hundred yards to the north-west of ,kalikoso1 where there is a little rise1 a decomposed quartz-porphyry is exposed displaying rounded crystals of quartz fractured in position1 the matrix of the rock being impregnated with chalcedony4 ,in one part of this mound there is a friable white rock1 composed of a crumbling mass of small irregular quartz-grains1 rarely showing crystal-faces4 ,it appears to be disintegrated quartz-felsite4 ,in taking the track from ,kalikoso to the village of ,vungalei1 which is distant about #b miles to the south-east1 one traverses after the first mile1 where the acid rocks terminate1 a rather more elevated region which rises to a maximum height of #ahj feet above the sea4 ,though the acid rocks give place to a semi-vitreous pyroxene-andesite as described on page #bab1 small fragments of chalcedonic flints are frequent on the surface over both areas4 ,the district that intervenes between ,kalikoso and the landing-place on the ,langa-langa ,river1 about two miles in length1 is not more than #cj feet above the sea1 and is crossed by small sluggish streams1 in the beds of which occur numerous fragments of silicified corals1 up to #c or #d inches in size1 belonging to the ,porites and ,astran type4 ,in these stream-beds also occur bits of mamillated chalcedony and of onyx1 flattish agates1 #c or #d inches across1 and pebbles of the compact pyroxene-andesite above alluded to1 the last probably derived from the south side of the plains4 ,the plains extend in a north-east direction as far as ,numbu1 which lies between #b and #c miles north-east of ,kalikoso4 ,the country between these two places is usually elevated between #fj and #ajj feet and is never more than #acj feet above the sea4 ,it is known as the ,kuru-kuru district4 ,the surface is strewn with the fragments of flints and of a white chalcedonic quartz-rock2 whilst the soil is friable and deep-red in colour1 limonite in abundant fragments occurring on the ground4 ,here and there one passes slabs of a hard white silicified tuff1 small portions of which are frequent on the surface4 ,silicified corals and earthy limonite are to be found in abundance scattered over the surface of the plains immediately surrounding the small lake of ,vakalalatha4 ,we also find lying on the ground in this district bits of chalcedony and onyx1 portions of chalcedonic flints1 and nodules of the size of the fist1 which when fractured either disclose the regular layers of the agate or radiating crystals of quartz4 ,the silicified corals occur usually in fragments not over #d inches across1 and include portions of branching corals of the ,madrepore habit1 bits of massive corals of the ,astran type1 small rounded nobs of 8,porites0 just as one commonly observes on a reef-flat1 c4 ,they have an ancient weathered look1 and in some cases it is evident from the existence of boring-shells in the fractured end of a branching coral that it once lay as a dead fragment on the surface of a reef-flat4 ,in ,chapter ,,xxv4 the characters of the silicified corals of the island are discussed in detail2 and ,i have there advanced the view that the extensive silicification of the ,kalikoso and ,wainikoro plains took place during the consolidation of the calcareous muds of a reef-flat whilst the land was emerging4 ,i have already alluded on page #bbb to an area of silicification on the neighbouring sea-border between ,visongo and ,tutu4 ,there can be no doubt that during the last stage of the emergence the present situation of the fresh-water lake near ,kalikoso was occupied by the sea1 which also extended far over the surrounding plains4 ,the process of silicification would of necessity be restricted to the period that has since elapsed2 and the discussion is therefore confined to the nature of the conditions under which this change was induced4 ,as a factor in the process we cannot disregard the acid character of the rocks of the district4 ,,the ,,undu ,,promontory ,the north-east portion of the island terminates in a long narrow promontory which ,i have named after ,undu ,point at its extremity4 ,commencing at ,thawaro ,bay and near ,tawaki it runs in a straight line for a distance of between #ac and #ad miles1 its breadth varying between #a and #b miles4 ,its greatest elevation of nearly #a1fjj feet is attained at its western end2 and it diminishes irregularly in height as one proceeds towards ,undu ,point1 where a height of #djj feet is maintained about a mile from the cape4 ,it is bordered by reefs sometimes a mile in breadth1 and the reefs prolong the promontory for another three miles beyond ,undu ,point4 ,as indicated by the #ajj-;fathom line1 the submarine contour corresponds to that of the land1 and the extent of marine erosion during the existing relations of land and sea is evidently displayed in the breadth of the reefs4 ,i found no sign of upraised reefs2 and although diligent inquiries were made nothing could be learned of any hot springs4 ,it will be seen from the following remarks that pumice-tuffs1 quartz-porphyries1 and oligoclase-trachytes1 are the prevailing rocks4 ,on the north side they may be regarded as continuous with the acid rocks of the region extending from near ,lambasa to ,thawaro ,bay4 ,on the south side they commence in the vicinity of ,tawaki4 7#a7 ,,the ,,district ,,extending ,,two ,,and ,a ,,half ,,miles ,,west ,,of ,,tawaki ,when proceeding eastward along the north coast of ,natewa ,bay one enters the region of acid rocks between #b and #b miles west of ,tawaki4 ,here the country is much broken1 picturesque hills with bare precipitous faces rising up near the coast1 one of which named ,natoto has a rudely conical and truncated form4 ,grey oligoclase-trachytes having a specific gravity of #bd and possessing the characters described on page #cjh1 prevail in the district extending west of ,tawaki4 ,sometimes they occur in mass2 but they often form agglomerates4 ,a singular pitchstone-agglomerate occurs at the coast at the foot of ,natoto4 ,the pitchstone1 which has a specific gravity of #bdh1 is a semi-vitreous form of a hypersthene-augite andesite4 ,it shows abundant small pyroxene prisms in its glassy groundmass and is referred to the prismatic sub-order 7#e7 described on page #bhi4 7#b7 ,,naithombothombo ,,range ,a high range of hills1 forming the backbone of this part of the island1 extends eastward for about five miles from ,thawaro and ,tawaki4 ,it is named 8,naithombothombo0 in the ,admiralty chart4 ,from it rise two conspicuous peaks1 ,thawaro ,peak 7#a1egc feet7 at its western end1 where it overlooks the village of that name1 and ,mount ,thuku 7#a1bhh feet7 near its eastern end4 ,west of ,thawaro ,peak this range is connected with the hills beyond by a saddle #fjj feet in height1 which is ascended when crossing the promontory from ,thawaro ,bay to ,tawaki4 7a7 ,thawaro ,peak4--,this represents an old 8volcanic neck0 of agglomerate rising out of the tuffs that are exposed on its slopes to an elevation of about #fjj feet4 ,as viewed from the saddle above mentioned1 the upper part of the hill presents bare precipitous sides1 several hundred feet in height1 of agglomerate1 the blocks of which are composed of a compact hypersthene-augite andesite 7sp4 gr4 #bdh74 ,it displays a few small phenocrysts of medium andesine and of rhombic and monoclinic pyroxene2 and is referred to the prismatic sub-order 7#e7 described on page #bhi1 characterised by prismatic pyroxene in the groundmass4 7b7 ,south coast between ,tawaki and the foot of ,mount ,thuku4--,the tall cliffs that rise to a height of from #bjj to #cjj feet behind ,tawaki are composed of white tuffs and agglomerate-tuffs derived from the acid rocks of the district4 ,eastward from ,tawaki to the base of ,mount ,thuku the coast scenery is particularly fine4 ,a little inland a line of hills1 named 8,na ,kula10 rises precipitously to a height of #gjj or #hjj feet1 and in the vertical sides are displayed tuffs and agglomerates probably of the character of those above noticed4 ,light-coloured tuffs are sometimes exposed at the coast in which are inclosed fragments varying in size of a pitchstone#ajd 7sp4 gr4 #bcf7 approaching in structure a trachytic glass4 ,at one place the tuffs were evidently sedimentary and bedded1 the dip being about #ae ,n4,w4 ,the massive rock most frequently exposed at the coast and on the hill-slopes between ,tawaki and ,mount ,thuku is a quartz porphyry#aje displaying abundant porphyritic crystals of quartz and felspar in a groundmass originally semi-vitreous but now obscurely felsitic in character4 ,the shore-flat for more than half a mile west of ,mount ,thuku is strewn with great numbers of detached columnar blocks1 #ab to #ae inches across1 of a slightly vesicular oligoclase-trachyte of the type described on page #cjh4 7c7 ,north coast between ,thawaro ,bay and the foot of ,mount ,thuku4--,coarse and fine tuffs prevail at the coast and on the neighbouring hill-slopes2 and in the bare rocky faces of the hills inland they are also to be observed4 ,the streams have worn deep gorges into their mass4 ,towards ,thuku they are acid and pumiceous1 and are evidently the products of eruption4 ,towards ,thawaro1 they are more basic and darker1 and are in part at least to be attributed to marine degradation4 7d7 ,mount ,thuku4--,my ascent of this hill1 which is #a1bhh feet in height1 was made from the north coast4 ,i found it to be composed from the foot to the summit of white pumiceous tuffs without any evident arrangement4 ,it has a narrow top and shows no sign of a crateral cavity4 ,the hills east and west1 as viewed from its summit1 are ridge-shaped and display nothing in their configuration at all suggestive of craters4 ,the pumice-tuffs of ,mount ,thuku are non-calcareous1 and exhibit greyish pumiceous lapilli in an abundant white matrix formed of fine pumice-debris4 ,under the microscope it shows the characteristic vacuolar and fibrillar structure2 but the material has not the fresh appearance of ordinary pumice and the minute cavities are often filled with alteration products4 ,the two rocky points on the north coast opposite the hill are formed in one case of a somewhat altered oligoclase-trachyte and in the other of a quartz-porphyry4 ,both no doubt represent intrusive masses1 the almost horizontal columns1 #ab to #ae inches in diameter1 of the former indicating a nearly vertical dyke4 7#c7 ,,the ,,undu ,,promontory ,,east ,,of ,,mount ,,thuku ,east of ,mount ,thuku the hilly backbone of the promontory is of much less elevation4 ,about three miles to the eastward the highest hill is #fcj feet1 and thence to within a mile or two of ,undu ,point the hills retain a height of #djj to #ejj feet4 7a7 ,the north coast between ,mount ,thuku and the coast village of ,nuku-ndamu4--,on this stretch of coast1 about five miles in length1 the shore-cliffs are composed of white and pale-yellow1 coarse and fine stratified pumice-tuffs1 the beds being either horizontal or with a gentle dip northward4 ,they are as a rule non-calcareous1 and contain some quartz grains and small bits1 #a to #c millimetres in size1 of bottle green compact obsidian1 much as one finds in ,lipari pumice-tuffs4 ,in general character1 both naked-eye and microscopic1 they correspond to the ,mount ,thuku pumice-tuffs above described4 ,large blocks of basic rocks are occasionally to be observed on this coast1 sometimes probably indicating dykes1 but in one place near ,mount ,thuku forming an agglomerate4 ,the rock is a dark-grey augite-andesite with a specific gravity of #bgg4 ,it is compact and has a hemi-crystalline groundmass4#ajf 7b7 ,the south coast between ,mount ,thuku and ,moala1 a distance of about five miles4--,pumice-tuffs and agglomerates are displayed at the coast1 the former often bedded and in one place having a dip of #ce or #dj degrees to the north4 ,a quartz-porphyry1 somewhat banded and a little altered1 and displaying rounded quartz crystals #c or #d millimetres in size1 is the prevailing massive rock exposed on the hill-slopes and occasionally at the coast4 ,it is well exhibited about a mile east of ,mount ,thuku4 ,blocks of a grey oligoclase-trachyte also occur4 ,these rocks are described on pages #cjh1 #cji4 7c7 ,the terminal portion of the promontory from ,nuku-ndamu and ,moala to ,undu ,point4--,the same pumiceous tuffs1 usually non-calcareous1 form the shore-cliffs on the south coast from ,moala to ,mr4 ,bulling's station at ,ndothiu1 which lies about #b miles from the point4 ,on the corresponding part of the north coast between ,nuku-ndamu and ,ndothiu these tuffs are often calcareous2 and near the first-named place they contain sub-angular bits of coral of the size of a walnut4 ,on the beach at ,vunikondi in this locality they are overlain by nearly horizontal beds of basic lava1 the upper surface of which when exposed displays the smooth1 8ropy0 crust of a lava flow4 ,the rock is a dark slightly vesicular augite-andesite1 hemi-crystalline in structure1 and containing a fair amount of residual glass4#ajg ,since the underlying tuffs were evidently deposited on a sea-bottom1 it follows that this is a submarine flow4 ,i intended to revisit this locality1 but was prevented4 ,a detailed examination of it would be worth undertaking4 ,from ,ndothiu to ,undu ,point1 about #b miles distant1 the interior of the promontory has an undulating surface1 the elevation being usually #bjj or #cjj feet and rising to #djj feet4 ,on the coasts are exposed bedded pumiceous tuffs1 steeply inclined and usually calcareous4 ,as displayed in the hill-slopes of the interior they are horizontally stratified and as a rule non-calcareous4 ,these deposits sometimes exhibit a spheroidal arrangement indicative of the proximity of a dyke4 ,in one or two places at the coasts occur basic agglomerates1 formed of the same augite-andesite lava-rock of which the ,vunikondi beds are composed1 but scoriaceous and containing more glass in the groundmass4 ,in the hand-specimen beside me1 the steam cavities are of all sizes1 from that of a pin-prick to a third of an inch 7#h mm47 and are generally elongated4 ,a careful search of the tuff-deposits in this part of the ,undu promontory ought to result in the discovery of remains1 both of plants and of marine mollusks4 ,mr4 ,chalmers informed me that fossilised tree-trunks occur on the coast near ,vunikondi2 but ,i was unfortunately not able to discover them4 99 99 99 99 99 ,,brief ,,summary ,,of ,,the ,,general ,,characters ,,of ,,the ,,undu ,,promontory ,,from ,,thawaro ,,and ,,tawaki ,,to ,,undu ,,point4--,one suggestive negative feature of this region is to be found in the absence1 as far as ,i could ascertain1 of any trace of a crater4 ,here also1 as in the area of acid rocks extending westward along the north side of the island to near ,lambasa1 hot springs are not to be found4 ,the prevailing rocks are in the first place the pumice-tuffs1 which not only as a rule form the coast-cliffs1 but occur inland as high as the summit of ,mount ,thuku almost #a1cjj feet above the sea4 ,they were probably in great part ejected from sub-arial vents1 though no doubt1 as in the vicinity of ,undu ,point1 they were often deposited under the sea4 ,the acid and basic tuffs in the vicinity of ,tawaki and ,thawaro are1 as ,i imagine1 largely derived from marine degradation4 ,next to the pumice-tuffs1 massive quartz-porphyries and oligoclase-trachytes are the characteristic rocks4 ,they are probably in most cases intrusive1 and present themselves sometimes as vertical columnar dykes1 evidently of considerable dimensions4 ,the basic rocks1 however1 are not unrepresented4 ,they occur in one or two places as agglomerates1 as in the vicinity of ,mount ,thuku on the north coast and near ,undu ,point2 whilst they form 8flows0 overlying the pumiceous tuffs at ,vunikondi4 ,occasional blocks lying on the surface on the north coast are indications of dykes4 ,the basic rocks1 nevertheless1 take a very secondary part in the composition of the ,undu ,promontory4 ,they are in most cases to be referred to the augite-andesites with a specific gravity #bf to #bgg2 but some1 as in the case of those forming the agglomerates of ,thawaro ,peak1 are hypersthene-augite andesites with specific gravity of about #be4 ,olivine-basalts are not represented4 ,the vents1 from which the materials forming this promontory were ejected1 were arranged in a single straight line for a length of #ad miles4 ,along this linear fissure1 which was probably submarine1 vents were at different times formed2 and though owing to sub-aerial and marine degradation the present surface has been since shaped and reshaped1 their situation may still be recognised in the 8necks0 of tuff and agglomerate that form the peaks1 and in the large dykes or sills of quartz-porphyry and oligoclase-trachyte4 ,,chapter ,,xvii ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu ,,the varied character of the volcanic rocks in my collection is brought out in the following ,table1 where ,i have grouped about #djj rock-sections1 excluding those of the tuffs and finer detrital deposits4 ,the small proportion of plutonic rocks should be noted4 ,olivine-basalts #bc per cent4 ,augite-andesites #dj ,hypersthene-augite-andesites #ag ,acid andesites1 including hornblende and quartz-andesites1 c4 #ab ,oligoclase-trachytes1 quartz-porphyries or rhyolites #f ,hypersthene-gabbros and diorites #b ---- #ajj ,in order to avoid the necessity of frequently describing rocks of the same type it has been found requisite to devise a method of classification4 ,in carrying out this somewhat laborious task ,i have often been surprised at the readiness with which rocks1 the relations of which had been previously very difficult to ascertain1 fell into their place in the scheme4 ,although many of my uncertainties have been thus removed1 a large number of doubtful points remain4 ,i venture to think1 however1 that others may be able to employ and also to extend the method of classification here employed4 ,the general plan followed has been worked out in detail for the olivine-basalts and the pyroxene-andesites of the more basic type2 whilst lack of materials has prevented its further elaboration in the case of the acid andesites1 oligoclase-trachytes1 quartz-porphyries1 c4 ,the treatment of all the classes has been uniform1 the scheme being the same whether applied to a basalt or to a dacite4 ,in describing the general method ,i will take the ,augite class4 ,as will be seen in the ,synopsis that follows1 this class is first divided according to the absence or presence of a groundmass into two sub-classes1 the first referring to the plutonic rocks1 which1 however1 are not represented in my collection1 the second comprising the augite-andesites which make up #dj per cent4 of the total4 ,these andesites are again divided into four orders1 according as the groundmass presents parallel or non-parallel felspar-lathes1 or short and stout felspars 7orthophyric71 or displays a felsitic character4 ,the last two orders are practically unrepresented here1 though many examples of them are found amongst the more acid andesites4 ,each order is then split up into three sub-orders depending on the nature of the pyroxene of the groundmass1 whether granular1 prismatic1 or ophitic4 ,each sub-order is broken up into two sections1 one displaying plagioclase-phenocrysts1 the other without them1 or possessing very few of them4 ,the first section is divided into two genera1 according to the character of the plagioclase-phenocrysts1 whether glassy or opaque1 the second genus often comprising rocks allied to the porphyrites4 ,the second or aphanitic section is subdivided into two genera according to the character of the pyroxene-phenocrysts2 in the one case they are macroporphyritic2 in the other they are either small or absent4 ,the genera are split into four species according to the length of the felspar-lathes1 a method which readily separates out the doleritic rocks4 ,in cases where the materials are abundant1 the genera have been first divided into porphyritic and non-porphyritic sub-genera1 based on the macroporphyritic or the micro-porphyritic character of the plagioclase-phenocrysts1 when present4 ,the species can be also split into sub-species1 according to the degree of basicity of the rocks1 as indicated by the specific gravity4 ,this method is fully worked out in the later pages and need not be further described here4 ,with abundant material from different regions it appears to me that a ready mode is here afforded of assigning to a rock its place in the scheme4 ,in this way it would be possible to follow the systematist in his method of comparing plants and animals from different localities4 ,to facilitate this end1 ,i have suggested in the synopsis the employment of abbreviations1 so that the description of the critical characters of a rock can be condensed into a formula capable of easy interpretation4 ,as an example of the use of these abbreviations ,i will take the instance of a common form of augite-andesite which is represented by the formula3--8,plag1 aug1 matr1 flu1 gran1 non-phen1 parv1 #a-b mm40 ,this is the formula for an aphanitic augite-andesite1 and it signifies that it is a rock of the plagioclase-augite class possessing a groundmass showing parallel felspar-lathes 7between #a and #b mm1 in average length7 and granular pyroxene1 and displaying no phenocrysts of plagioclase or only a very few of small size1 whilst pyroxene phenocrysts if present are micro-porphyritic4 ,as another example the following formula for a type of porphyrite found in this island may be given3--,plag1 hypersth-aug1 matr1 orth1 prism1 phen1 opac4 ,this is an andesite in which rhombic and monoclinic pyroxene are associated both in the phenocrysts and in the groundmass where the pyroxene is prismatic and not granular4 ,the plagioclase phenocrysts are opaque and the felspars of the groundmass are of the orthophyric type4 ,there are one or two points that require further reference4 ,in the first place the early employment in the scheme of the characters of the felspars of the groundmass for distinguishing the orders scarcely seems needed in the cases where they take the lathe-form2 but the importance of its early use is shown in the acid andesites where it is certainly of prime importance in an early stage of the classification to distinguish the rocks by the character of the felspars of the groundmass1 whether lathe-like1 orthophyric1 or felsitic4 ,it may also be objected that the two orders obtained by dividing the lathe group into 8parallel0 and 8non-parallel0 divisions are not equivalents of the two other orders1 the orthophyric and the felsitic4 ,the distinction1 however1 between the flow or non-flow arrangement1 though in practice not always readily established1 is a far-reaching one4 ,on priori grounds the first division might be expected to have no plutonic equivalent2 whilst in the second division1 it is easy to trace the gradations through the doleritic stage1 where the felspar-lathes are very large1 to the granitoid condition4 ,then1 again1 the ophitic habit is as a general rule confined to rocks with a doleritic or semi-doleritic groundmass1 where the felspar-lathes are coarse and form a mesh-work4 ,two quite distinct lines of development unite in the felspar-lathes and begin to diverge with the difference in their arrangement in the groundmass4 ,the nature of the difference between the flow and non-flow arrangement of the felspar-lathes is well brought out in some dykes of basalt and augite-andesite that ,i examined in this island and also in the ,valle del ,bove on the ,etna slopes4 ,in the outer vitreous portion the felspar-lathes1 which are fairly well represented1 are all about the same length and are more or less parallel with the sides of the dyke4 ,in the central more crystalline portion two sets of lathes can be distinguished1 one 7,a7 corresponding in the average length and in the flow-arrangement with the lathes of the borders1 the other 7,b7 being about half the length and forming a plexus between the larger parallel lathes4 ,those of the ,a set1 which are those that usually catch the eye in a section1 are contemporaneous in their origin with those in the margins of the dyke2 whilst those of the ,b set have been subsequently formed4 ,in the preliminary 8stiffening0 of the first stage of consolidation1 the whole mass of the dyke would be affected4 ,to this stage the lathes of the ,a set belong2 whilst to the later stage of consolidation which would proceed much more slowly in the interior than at the margins of the dyke1 the lathes of the ,b set are to be referred4 ,this distinction so plainly illustrated in a dyke must be postulated for all intrusive masses2 but ,i have not yet found it possible to make much use of it4 ,much ground will have first to be cleared before it can be safely employed1 since it is apparent1 for instance1 that there are often all gradations in a slide between a lathe and a phenocryst1 and that the term 8phenocryst0 is applied to crystals having very different histories4 ,illustration3 ,diagram illustrating the two sets of felspar-lathes in a dyke3 ,a1 long and parallel1 dispersed through the mass4 ,b1 short and non-parallel and found only in the centre4 ,with regard to the ophitic habit of some of the basaltic rocks the following conclusions may be drawn3 7a7 ,typical ophitic 8plates0 are not very common in the slides4 ,more frequently the habit of the pyroxene is semi-ophitic4 7b7 ,this character is as a general rule associated with the plexus or non-fluidal arrangement of the felspar lathes4 7c7 ,the felspar-lathes are nearly always large1 frequently averaging more than #b mm4 in length4 ,this coarse doleritic groundmass is almost diagnostic of an ophitic rock4 99 99 99 99 99 ,it is not always possible to allow for the influence of locality in drawing up such a classification as this1 since it is well known that in each volcanic region the rocks have a particular facies recognisable in hand-specimens as well as in the slide1 though it is not easy to express such a distinction in a definition4 ,perhaps this is represented in 8adaptation0 as we find it in the organic world1 and the question arises as to the value of such characters for critical purposes4 ,regional variation plays such an important part that it cannot be ignored in rock-classification4 ,,synopsis ,i4 ,,class4--,,olivine ,,rocks 7,plag41 oliv474 ---------------------------------------- --------------------------- ,,sub-,,class4 ,,division4 ,,order4#ajh ---------------------------------------- --------------------------- #a4 ,no groundmass 7non-matr47 ,,limburgites1 7,not represented in collection47 ,,peridotites1 ,,olivine ,,gabbros1 etc4 #a4 ,felspar lathes not #a4 in flow-arrangement ,olivine abundant 7non-flu474 7cop47 #b4 ,felspar lathes #b4 in flow-arrangement ,groundmass 7flu474 7matr47 ,,olivine-,,basalts #c4 ,felspar lathes not #b4 in flow-arrangement ,olivine 7non-flu474 relatively #d4 scanty ,felspar lathes 7pauc474 in flow-arrangement 7flu474 ---------------------------------------- --------------------------- ,,ii4 ,,class4--,,augite ,,rocks 7,plag41 aug474 ---------------------------------------- ---------------------------- ,,sub-,,class4 ,,order4 ---------------------------------------- ---------------------------- #a4 ,no groundmass ,not represented in collection4 7non-matr47 ,,gabbros1 in part4 #a4 ,felspar lathes not in flow-arrangement 7non-flu474 #b4 ,groundmass 7matr47 #b4 ,,basaltic ,,andesites2 ,felspar lathes in flow-arrangement ,,augite-,,andesites2 7flu474 ,,pyroxene-,,andesites #c4 in part4 ,felspars short and broad 7orthophyric1 orth474#aji #d4 ,groundmass felsitic 7fels47#aji ---------------------------------------- ---------------------------- ,,iii4 ,,class4--,,hypersthene-,,augite ,,rocks 7,plag41 hypersth4-aug474 ---------------------------------------- --------------------------- ,,sub-,,class4 ,,order4 ---------------------------------------- --------------------------- #a4 ,no groundmass 7non-matr47 ,represented by the ,hypersthene-gabbros ,,gabbros1 in part4 in collection4 #a4 ,felspar lathes not in flow-arrangement 7non-flu474 #b4 #b4 ,felspar lathes in flow-arrangement ,groundmass 7matr47 7flu474 ,,pyroxene-,,andesites1 in part4 #c4 ,felspars of the groundmass short and broad 7orthophyric1 orth474 #d4 ,groundmass granular or presenting a mosaic 7felsitic1 fels474 ---------------------------------------- --------------------------- ,,iv4 ,,class4--,,hypersthene ,,rocks4 ,v4 ,,class4--,,hornblende-,,hypersthene ,,rocks4 ,,vi4 ,,class4--,,quartz-,,hornblende-,,hypers thene ,,rocks ,,or ,,dacites4 ,these last three classes are merely provisional4 ,they include the ,acid ,andesites of ,vanua ,levu1 which are all characterised by the prevalence of rhombic pyroxene amongst the phenocrysts and by its predominance or rather by its usually exclusive occurrence in the groundmass4 ,all the classes are capable of being split up into two sub-classes and four orders as in the case of the third class4 ,the characters of these rocks are given in ,chapter ,,xxi4 ,,vii4 ,,class4--,,hornblende ,,rocks4 ,in this class are included those rocks where hornblende is the only ferro-magnesian mineral4 ,it is only represented by two diorites described on page #bea4 ,,viii4 ,,class4--,,oligoclase-,,trachytes4 ,,ix4 ,,class4--,,quartz-,,porphyries ,,and ,,rhyolites ,described in ,chapter ,,xxi4 ,,first ,,order ,,of ,,the ,,olivine ,,basalts4 ,,characters4--,olivine in abundance4 ,felspars of the groundmass not in flow-arrangement4 ,,formula4--,oliv41 matr41 cop41 non-flu4 ---------------------------------------- ------------------------- ,,sub-,,order4 ,,section4 ,,genus4 ,,species4 ---------------------------------------- ----------- ,presence or ,number of ,pyroxene absence of ,character ,length specimens4 of the plagioclase of the of felspar groundmass4 phenocrysts4 phenocrysts4 lathes4 ---------------------------------------- ------------------------- #a4 #jb-a mm4 #a ,glassy #a-b #b #a4 plagioclase #b-c ,plagioclase phenocrysts #c-e phenocrysts 7vitr47 7phen47 #b4 #jb-a mm4 ,opaque #a-b #a plagioclase #b-c #b phenocrysts #c-e 7opac47 #a4 ,granular #c4 7gran47 ,large #jb-a mm4 phenocrysts #a-b of olivine #b-c #b4 and #c-e #a ,no pyroxene1 plagioclase over #b mm4 phenocrysts 7magn47 7non-phen47 #d4 ,small #jb-a mm4 phenocrysts #a-b of olivine #b-c and #c-e #a pyroxene under #b mm4 ,pyroxene scanty and often absent 7parv47 #e4 ,vitr4 #c4 ,phen4 #b4 #f4 ,opac4 ,prismatic ,not 7prism47 #g4 ,magn4 represented4 #d4 ,non-phen4 #h4 ,parv4 #i4 ,vitr4 #e4 ,phen4 ,not #c4 #aj4 ,opac4 represented4 ,ophitic 7oph47 #aa4 ,magn4 ,not #f4 ,non-phen4 represented4 #ab4 ,parv4 #a-b mm4 #a ---------------------------------------- ------------------------- ,,second ,,order ,,of ,,the ,,olivine-,,basalts4 ,,characters4--,olivine in abundance4 ,felspars of the groundmass in flow-arrangement4 ,,formula4--,oliv41 matr41 cop41 flu4 ---------------------------------------- ------------------------- ,,sub-,,order4 ,,section4 ,,genus4 ,,species4 ---------------------------------------- ----------- ,presence or ,number of ,pyroxene absence of ,character ,length specimens4 of the plagioclase of the of felspar groundmass4 phenocrysts4 phenocrysts4 lathes4 ---------------------------------------- ------------------------- #ac4 #jb-a mm4 #c ,glassy #a-b #b plagioclase #b-c #a #g4 phenocrysts #c-e ,plagioclase 7vitr47 phenocrysts 7phen47 #ad4 #jb-a mm4 ,opaque #a-b #c plagioclase #b-c phenocrysts #c-e 7opac47 #d4 ,granular #ae4 7gran47 ,large #jb-a mm4 #b phenocrysts #a-b of olivine #b-c and #c-e pyroxene1 over #b mm4 7magn47 #h4 ,no #af4 plagioclase ,small phenocrysts phenocrysts 7non-phen47of olivine #jb-a mm4 #a and #a-b #e pyroxene1 #b-c #b under #b mm4 #c-e #a ,pyroxene scanty and often absent 7parv47 #ag4 ,vitr4 #i4 ,phen4 #e4 #ah4 ,opac4 ,not ,prismatic represented4 7prism47 #ai4 ,magn4 #aj4 ,non-phen4 #bj4 ,parv4 #ba4 ,vitr4 #aa4 ,phen4 #f4 #bb4 ,opac4 ,not ,ophitic represented4 7oph47 #bc4 ,magn4 #ab4 ,non-phen4 #bd4 ,parv4 ---------------------------------------- ------------------------- ,,third ,,order ,,of ,,the ,,olivine-,,basalts4 ,,characters4--,olivine scanty4 ,felspars of the groundmass not in flow-arrangement4 ,,formula4--,oliv41 matr41 pauc41 non-flu4 ---------------------------------------- ------------------------- ,,sub-,,order4 ,,section4 ,,genus4 ,,species4 ---------------------------------------- ----------- ,presence or ,length ,number of ,pyroxene absence of ,character of felspar specimens4 of the plagioclase of the lathes and groundmass4 phenocrysts4 phenocrysts4 prisms4 ---------------------------------------- ------------------------- #be4 #jb-a mm4 #a ,glassy #a-b #ac #ac4 plagioclase #b-c #e ,plagioclase phenocrysts #c-e phenocrysts 7vitr47 7phen47 #bf4 #jb-a mm4 ,opaque #a-b #d plagioclase #b-c phenocrysts #c-e #g4 7opac47 ,granular 7gran47 #bg4 ,large #jb-a mm4 phenocrysts #a-b ,not of olivine #b-c represented4 and #c-e #ad4 pyroxene1 ,no over #b mm4 plagioclase 7magn47 phenocrysts 7non-phen47 #bh4 ,small phenocrysts#jb-a mm4 of olivine #a-b ,not and #b-c represented4 sometimes #c-e pyroxene1 under #b mm4 7parv47 #bi4 ,vitr4 #ae4 ,phen4 #h4 #cj4 ,opac4 ,not ,prismatic represented4 7prism47 #ca4 ,magn4 #af4 ,non-phen4 #cb4 ,parv4 #jb-a mm4 #cc4 ,vitr4 #a-b #c #ag4 ,phen4 #b-c #a #i4 #c-e #b ,ophitic ,not 7oph47 #cd4 ,opac4 represented4 #ce4 ,magn4 ,not #ah4 represented4 ,non-phen4 #cf4 ,parv4 ---------------------------------------- ------------------------- ,,fourth ,,order ,,of ,,the ,,olivine-,,basalts4 ,,characters4--,olivine scanty4 ,felspar-lathes of the groundmass in flow-arrangement4 ,,formula4--,oliv41 matr41 pauc41 flu4 ---------------------------------------- ------------------------- ,,sub-,,order4 ,,section4 ,,genus4 ,,species4 ---------------------------------------- ----------- ,presence or ,pyroxene absence of ,character ,length ,number of of the plagioclase of the of felspar specimens4 groundmass4 phenocrysts4 phenocrysts4 lathes4 ---------------------------------------- ------------------------- #cg4 #jb-a mm4 #b ,glassy #a-b #ab plagioclase #b-c #f #ai4 phenocrysts #c-e ,plagioclase 7vitr47 phenocrysts 7phen47 #ch4 #jb-a mm4 ,opaque #a-b #b plagioclase #b-c phenocrysts #c-e #aj4 7opac47 ,granular 7gran47 #ci4 ,large #jb-a mm4 phenocrysts #a-b ,not of olivine #b-c represented4 and #c-e pyroxene1 #bj4 over #b mm4 ,no 7magn47 plagioclase phenocrysts #dj4 7non-phen47 ,small phenocrysts#jb-a mm4 of olivine #a-b and #b-c #b sometimes #c-e #a pyroxene1 under #b mm4 7parv47 #da4 ,vitr4 #ba4 ,phen4 ,not #aa4 #db4 ,opac4 represented4 ,prismatic 7prism47 #dc4 ,magn4 ,not #bb4 represented4 ,non-phen4 #dd4 ,parv4 #jb-a mm4 #a #ab4 ,ophitic ,not 7oph47 represented4 ---------------------------------------- ------------------------- ,,first ,,order ,,of ,,the ,,augite-,,andesites4 ,,characters4--,felspar lathes or prisms of the groundmass not in flow-arrangement4 ,,formula4--,aug41 matr41 non-flu4 ---------------------------------------- ------------------------- ,,sub-,,order4 ,,section4 ,,genus4 ,,species4 ---------------------------------------- ----------- ,presence or ,length of ,number of ,pyroxene absence of ,character felspar specimens4 of the plagioclase of the lathes and groundmass4 phenocrysts4 phenocrysts4 prisms4 ---------------------------------------- ------------------------- #a4 #jb-a mm4 #i ,glassy #a-b #e plagioclase #b-c #d #a4 phenocrysts #c-e ,plagioclase 7vitr47 phenocrysts 7phen47 #b4 #jb-a mm4 #f ,opaque #a-b #d plagioclase #b-c #c phenocrysts #c-e #c #a4 7opac47 ,granular 7gran47 #c4 ,large phenocrysts ,not of augite1 represented4 #b4 over #b mm4 ,no 7magn47 plagioclase phenocrysts #d4 7non-phen47 ,small phenocrysts#jb-a mm4 of augite1 #a-b #c under #b-c #a #b mm41 #c-e #b or none 7parv47 #jb-a mm4 #a #e4 ,vitr4 #a-b #b #c4 ,phen4 #b4 #f4 ,opac4 #a-b #b ,prismatic 7prism47 #g4 ,magn4 ,not #d4 represented4 ,non-phen4 #h4 ,parv4 #jb-a mm4 #a #a-b #c #i4 ,vitr4 #b-c #d #e4 ,phen4 #c-e #g #c4 #b-c mm4 #a ,ophitic #aj4 ,opac4 #c-e #a 7oph47 #aa4 ,magn4 #f4 ,non-phen4 #ab4 ,parv4 #b-c mm4 #c #c-e #c ---------------------------------------- ------------------------- ,,second ,,order ,,of ,,the ,,augite-,,andesites4 ,,characters4--,felspar-lathes of the groundmass in flow-arrangement4 ,,formula4--,aug41 matr41 flu4 ---------------------------------------- ------------------------- ,,sub-,,order4 ,,section4 ,,genus4 ,,species4 ---------------------------------------- ----------- ,presence or ,length of ,number of ,pyroxene absence of ,character felspar ,specimens4 of the plagioclase of the lathes and groundmass4 phenocrysts4 phenocrysts4 prisms4 ---------------------------------------- -------------------------- #ac4 #jb-a mm4 #aj ,glassy #a-b #aj plagioclase #b-c #d #g4 phenocrysts #c-e #a ,plagioclase 7vitr47 phenocrysts 7phen47 #ad4 ,opaque phenocrysts#jb-a mm4 #b #d4 of ,granular plagioclase 7gran47 7opac47 #ae4 ,large ,not #h4 phenocrysts represented4 ,no 7or very of augite1 few and small7 over #b mm4 plagioclase 7magn47 phenocrysts 7non-phen47 #af4 #jb-a mm4 #ab ,small augite #a-b #ad phenocrysts1 #b-c #d under #b mm4 #c-e #c or none 7parv47 #ag4 ,vitr4 #a-b mm4 #a #i4 ,phen4 ,not #ah4 ,opac4 represented4 #e4 ,prismatic ,not 7prism47 #ai4 ,magn4 represented4 #aj4 #jb-a mm4 #d ,non-phen4 #bj4 ,parv4 #a-b #d #ba4 ,vitr4 #a-b mm4 #c #aa4 ,phen4 ,not #f4 #bb4 ,opac4 represented4 ,ophitic 7oph47 #bc4 ,magn4 #ab4 ,not ,non-phen4 #bd4 ,parv4 represented4 ---------------------------------------- ------------------------- ,,first ,,order ,,of ,,the ,,hypersthene-,,augite ,,andesites4 ,,characters4--,felspar-lathes not in flow-arrangement4 ,,formula4--,hypersth4-aug41 matr41 non-flu4 ---------------------------------------- ------------------------- ,,sub-,,order4 ,,section4 ,,genus4 ,,species4 ---------------------------------------- ----------- ,presence or ,number of ,pyroxene absence of ,character ,length specimens4 of the plagioclase of the of felspar groundmass4 phenocrysts4 phenocrysts4 lathes4 ---------------------------------------- ------------------------- #a4 ,glassy #jb-a mm4 #ab plagioclase #a-b #d phenocrysts #a4 7vitr47 ,plagioclase phenocrysts #b4 7phen47 ,opaque ,not phenocrysts represented4 of #a4 plagioclase ,granular 7opac47 7gran47 #c4 ,large phenocrysts ,not of represented4 pyroxene1 #b4 over #b mm4 ,no plagioclase 7magn47 phenocrysts 7non phen47 #d4 ,small pyroxene #c-e mm4 #a phenocrysts1 under #b mm41 or none 7parv47 #jb-a mm4 #b #e4 ,vitr4 #a-b #b #c4 ,phen4 #b4 #jb-a mm4 #a ,prismatic #f4 ,opac4 #a-b #a 7prism47 #g4 ,magn4 #d4 ,non phen4 ,not #h4 ,parv4 represented4 #i #c4 #aj ,not ,ophitic #aa represented4 7oph47 #ab ---------------------------------------- ------------------------- ,,second ,,order ,,of ,,the ,,hypersthene-,,augite ,,andesites4 ,,characters4--,felspar-lathes in flow-arrangement4 ,,formula4--,hypersth4-aug41 matr41 flu4 ---------------------------------------- ------------------------- ,,sub-,,order4 ,,section4 ,,genus4 ,,species4 ---------------------------------------- ----------- ,presence or ,number of ,pyroxene absence of ,character ,length specimens4 of the plagioclase of the of felspar groundmass4 phenocrysts4 phenocrysts4 lathes4 ---------------------------------------- ------------------------- #ac4 ,glassy #jb-a mm4 #i plagioclase #a-b #b #g4 phenocrysts ,plagioclase 7vitr47 phenocrysts 7phen47 #ad4 ,opaque ,not phenocrysts represented4 of #d4 plagioclase ,granular 7opac47 7gran47 #ae4 ,large phenocrysts ,not of pyroxene1 represented4 over #b mm4 #h4 7magn47 ,no plagioclase phenocrysts #af4 7non-phen47 ,small pyroxene ,not phenocrysts1 represented4 under #b mm41 or none 7parv47 #ag4 ,vitr4 #jb-a mm4 #b #i4 ,phen4 #e4 #ah4 ,opac4 #jb-a mm4 #d ,prismatic 7prism47 #ai4 ,magn4 ,not #aj4 represented4 ,non-phen4 #bj4 ,parv4#jb-a mm4 #d #a-b #b #f4 #ba ,ophitic #bb ,not 7oph47 #bc represented4 #bd ---------------------------------------- ------------------------- ,,third ,,order ,,of ,,the ,,hypersthene-,,augite ,,andesites4 ,,characters4--,felspars of the groundmass short and stout 7orthophyric74 ,,formula4--,hypersth4-aug41 matr41 orth4 ,,remarks4--,the same classification is to be employed here as in the case of the two previous orders1 but as the rocks in my collection that belong to this order are not numerous 7nine sections71 it will be sufficient to refer to the general remarks on the order on p4 #bij4 ,,fourth ,,order ,,of ,,the ,,hypersthene-,,augite ,,andesites4 ,,characters4--,groundmass presenting a rudely granular appearance or blurred mosaic 7microfelsitic74 ,,formula4--,hypersth4-aug41 matr41 fels4 ,,remarks4--,my sliced specimens 7five7 are too few for the elaboration of this order to which the classification employed for the other orders is scarcely applicable4 ,this is due to the partial decomposition or imperfect development of the pyroxene of the groundmass4 ,the general characters of the order are given on p4 #bia4 ,,the ,,plutonic ,,rocks4 ,these rocks are very infrequent and are for the most part hypersthene-gabbros or norites1 with a few representatives of diorites#aaj without pyroxene4 ,true plutonic rocks did not come under my observation in the western half of the island 7west of ,lambasa and ,savu-savu71 those of ,mount ,thoka-singa in the ,ndrandramea district making the nearest approach 7see p4 #cjb74 ,the localities in which they were found are below enumerated3-- ---------------------------------------- ------------------------- ,mode of ,no4 ,nature of rock4 ,locality4 occurrence4 ,page4 ---------------------------------------- ------------------------- #a ,hypersthene-gabbro ,avuka ,range ,probably forms between ,lambasa the axis of the and ,mbuthai-sau range4 #ahj #b ,ditto ,nawi1 at the ,deep-seated4 #baa head of the ,vui-na-savu ,river #c ,ditto ,valanga ,range ,probably forms between the axis of the ,savu-savu and range4 #ahb ,natewa ,bays #d ,ditto ,ridge at the ,ditto4 #ahd head of ,na ,kula valley between ,savu-savu and ,natewa ,bays4 #e ,hornblende-gabbro4 ,ditto ,ditto4 #ahd #f ,diorite ,vunimbua ,river1 ,loose blocks in on south side of river-bed4 #ahb the ,mariko ,range #g ,ditto ,coast cliffs ,large block in west of the ,salt agglomerate-tuff4 #aic ,lake ,passage ---------------------------------------- ------------------------- ,,the ,,hypersthene-,,gabbros4--,these rocks also contain monoclinic pyroxene1 and are the plutonic equivalents of the hypersthene-augite-andesites which as a rule prevail in the localities where these rocks occur4 ,they are usually dark grey or steel-grey in colour with a specific gravity ranging from #bg to #bhd and have a granitoid aspect4 ,the following characters are common to all the specimens4 ,they display a mixture of plagioclase and pyroxene1 the last filling up the spaces between the felspars and apparently of later formation4 ,the plagioclase crystals1 which are #a to #b mm4 in size1 are opaque2 and since they are traversed by numerous fine fissures filled with dust-like decomposition products1 their appearance is often semi-saussuritic4 ,they are much cross-macled1 are at times zoned1 and give lamellar extinctions of andesine-labradorite 7#bj-cj74444 ,the pyroxene includes both the rhombic and monoclinic forms1 the last with extinction angles of over #cj4 ,they may be associated or may occur as separate crystals1 the rhombic prevailing in the less basic and the monoclinic in the more basic rocks4 ,the rhombic pyroxene is usually more or less converted into bastite which by further change passes into a chloritic material2 whilst the augite sometimes undergoes the diallagic change resulting from schillerisation4 ,some special features are presented by rocks from different localities4 ,that from ,nawi is most basic and looks like a diallage-gabbro4 ,that from the ,valanga ,range 7sp4 gr4 #bge7 contains some quartz1 apparently secondary and filling up the interspaces4 ,the rock from the ,na ,kula ,ridge shows traces of a groundmass2 but it comes near the plutonic type4 ,a ,,hornblende-,,gabbro4--,this granitoid rock1 which is from the ,na ,kula ,ridge1 has a specific gravity of #bgb4 ,hand-specimens display large porphyritic crystals of hornblende 7#g mm4 long7 in a base of opaque felspar and smaller hornblende4 ,in the slide we observe besides the large crystals of plagioclase and hornblende a little pyroxene2 but the mass of the rock consists of greenish-brown hornblende1 plagioclase1 and some secondary quartz1 forming a coarse mosaic with a 8grain0 of about a millimetre4 ,the hornblende is displayed in regular hexagonal sections1 markedly pleochroic1 and gives extinctions up to #ab4 ,it shows no dark resorption borders2 and the larger porphyritic crystals have the same characters4 ,almost all the plagioclase of the rock is traversed by numerous fine fissures1 and often acquires a semi-saussuritic appearance from the presence of dust-like decomposition products4 ,the lamellar extinctions indicate andesine-labradorite4 ,the quartz occurs mostly in nests4 ,the pyroxene is formed of large grains of both the monoclinic and rhombic types4 ,,the ,,diorites4--,the rock forming blocks in the ,vunimbua ,river has a specific gravity of #bgh to #bh4 ,it is a pretty rock showing long black blades of hornblende1 #aj mm4 in length1 in an opaque felspar base4 ,in the slide the hornblende1 which is dark brown and markedly pleochroic1 shows six-sided sections with characteristic prismatic cleavage lines1 the longitudinal sections giving extinctions up to #ae4 ,the borders in some cases display traces of resorption4 ,the felspar 7plagioclase7 is in the form usually of broad regular crystals1 #c to #d mm4 in size1 and giving extinctions of andesine-labradorite 7#bh72 they are 8clouded0 through the presence of fine alteration products associated with numerous fissures4 ,the relation between the hornblende and the plagioclase is not constant4 ,this appears to be partially due to the occurrence of traces of a groundmass4 ,the diorite forming blocks in the agglomerate of the coast cliffs1 west of the ,salt ,lake ,passage1 is a remarkable rock showing large blackish hornblende crystals1 in the shape of blades #be mm4 long and #c or #d mm4 broad1 set in a base of opaque plagioclase felspar which surrounds the hornblende4 ,the last-named is deep-brown1 very pleochroic1 yields extinctions up to #bb1 and displays but little evidence of resorption4 ,the plagioclase is irregular in shape and exhibits broad lamell giving extinctions of acid labradorite 7#bh-cj74 ,it is traversed by numerous fine fissures filled with decomposition products and contains abundant dust-like materials4 7,spec4 grav4 #bh74 ,,chapter ,,xviii ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,,olivine ,,class ,,sub-,,class ,,ii ,,the ,,olivine ,,basalts 7,plag1 oliv1 matr47 ,,this sub-class includes the plagioclase-olivine-basalts4 ,although these rocks are not the most numerous of the basic rocks1 they are well represented in the island1 being in great part confined to the western half1 and being especially characteristic of the districts of ,wainunu and ,solevu and of the mountains of ,seatura and ,naivaka4 ,it will be seen from the ,synopsis that this sub-class is split up into two divisions1 according to the relative abundance of the olivine4 ,many of the rocks are grey basalts with the olivine more or less hematised2 but the majority are blackish with the olivine usually more or less serpentinised4 ,in the typical blackish rocks there is a little dark opaque interstitial glass4 ,in the grey basalts the groundmass is as a rule holo-crystalline4 ,the specific gravity ranges generally from #bh to #c4 ,it will be noticed in the scheme that the 8prismatic0 sub-orders1 where the pyroxene of the groundmass is for the most part in prisms1 are scarcely represented4 ,the 8ophitic0 sub-orders are poorly represented1 since they only include about #aj per cent4 of the total4 ,the ophitic olivine-basalts are indeed mostly confined to the division where the olivine is scanty1 and the felspars of the groundmass are for the most part not parallel1 the plexus arrangement1 as will be often pointed out1 being almost essential for the development of the ophitic structure4 ,with the basaltic andesites1 which cannot always be sharply separated from the basalts with scanty olivine1 the proportion of ophitic rocks is much higher1 probably about #bj per cent4 ,the pyroxene in the olivine-basalts is nearly always augite1 intergrowths with rhombic pyroxene being only occasionally observed4 ,i4 ,,division ,,of ,,the ,,olivine-,,basalts ,,characters4--,abundant olivine4 ,,formula4--,oliv1 matr1 cop4 ,these rocks are characterised by abundant olivine usually as phenocrysts but sometimes represented in the groundmass4 ,when a basalt presents much of this mineral in an ordinary hand-specimen and displays at least five or six phenocrysts in a slide1 it is placed in this division4 ,olivine-basalts of this character are well exhibited in the hills around ,solevu ,bay and in the neighbouring ,seatovo ,range4 ,they are also fairly represented on the northern slopes of ,mount ,seatura1 on the coast between the ,wainunu ,river and ,nandi ,bay1 and on the ,wainunu basaltic tableland4 ,in the ,ulu-i-ndali ,range1 which lies east of the ,wainunu estuary1 they are especially frequent4 ,whilst confined mostly to the portion of the island west of ,savu-savu ,bay1 they occur sporadically in other localities to the eastward1 as in ,na ,suva-suva ,hill and in some parts of the ,natewa ,peninsula4 ,the grey basalts1 which form one-third of the total1 are chiefly characteristic of the hill of ,ulu-i-ndali1 of the ,solevu district1 and of the northern slopes of ,seatura4 ,whilst the blackish basalts usually compose the flows1 the grey basalts form dykes and volcanic necks4 ,two-thirds of these olivine-basalts belong to the order presenting flow-structure and almost all 7#bh out of #bi7 are included in the sub-order exhibiting granular augite in the groundmass4 ,the ophitic structure is displayed in only one case2 and the prismatic form of the augites is never a predominant feature4 #a4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 non-flu1 gran1 phen1 vitr4 ,,characters4--,abundant olivine4 ,felspar-lathes of the groundmass not in flow arrangement4 ,pyroxene of the groundmass granular4 ,phenocrysts of glassy plagioclase4 ,,description4--,dark-brown or blackish rocks4 ,sp4 gr4 #bhh to #bic4 ,phenocrysts of pyroxene occur in fair quantity in addition to those of the olivine and plagioclase4 ,the groundmass displays a plexus of felspars and augite-granules with much magnetite in grains and irregular patches4 ,the interstitial glass is scanty or almost absent4 ,the olivine phenocrysts1 of which the larger are #c to #d mm4 in size1 are as a rule hematised at the borders and in the fissures1 and are sometimes partially serpentinised4 ,in some cases small crystals of olivine are enclosed in the pyroxene-phenocrysts4 ,the plagioclase phenocrysts do not usually exceed #b mm4 in size4 ,they give lamellar extinctions of #ae-bh1 and are often cross-macled4 ,they generally contain magma-inclusions1 which may be arranged in zones1 and they sometimes inclose small pyroxene crystals4 ,their borders are often eroded4 ,the pyroxene-phenocrysts1 which frequently are #c to #d mm4 in size1 give extinctions of #cj and over1 and may be described as composed of brown augite4 ,it is only at times that intergrowths of rhombic pyroxene occur4 ,they are often twinned and are sometimes eroded and may contain magma and other inclusions4 ,the felspars of the groundmass1 which for the most part form a plexus1 are small and stout1 their average length varying from #jh to #ac mm41 whilst they frequently display lamellar twinning and give extinctions of about #ae 7oligoclase-andesine74 ,the pyroxene-granules of the groundmass1 which are of brown augite1 vary in average size from #jb to #jd mm4 ,two of the four species1 where the felspar-lathes are less than #a mm4 and between #a and #b mm4 in length1 are represented in this collection4 #b4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 non-flu1 gran1 phen1 opac4 ,,characters4--,abundant olivine4 ,felspar-lathes of the groundmass not in flow-arrangement4 ,pyroxene of the groundmass granular4 ,phenocrysts of plagioclase opaque white4 ,,description4--,grey compact-looking rocks2 sp4 gr4 #bhc to #bi4 ,interstitial glass scanty4 ,the olivine phenocrysts1 which range up to #e mm4 in size1 are more or less hematised2 and in extreme cases of this alteration1 where schiller-planes are formed1 the hand-specimen appears to carry brown mica4 ,there are sometimes small grains of olivine 7#a mm47 in the groundmass4 ,the plagioclase-phenocrysts1 varying in size from #b to #d mm41 owe their opacity partly to their composite character1 when they present an aggregate of smaller clear crystals1 and partly to multiple macling4 ,they give extinctions of acid labradorite 7#be-cb74 ,pyroxene-phenocrysts1 when present1 are scanty1 pale brown1 not over #b mm4 in size1 and give the large extinctions 7#cj7 of augite4 ,in their absence small augites 7#b mm47 are frequent4 ,fine granules 7#ja-jc mm47 of similar augite1 together with magnetite1 abound in the groundmass4 ,the felspars of the groundmass are fairly stout and lathe-like and show at times a few twin-lamell which give extinctions of #ac to #bj 7medium andesine74 ,species represented3 7a7 felspar lathes #a-b mm4 7b7 felspar lathes #b-c mm4 #c4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 non-flu1 gran1 non-phen1 magn4 ,,characters4--,abundant olivine4 ,felspar-lathes of the groundmass not in flow-arrangement4 ,pyroxene of the groundmass granular4 ,no plagioclase phenocrysts4 ,large phenocrysts of olivine and pyroxene over #b mm4 in size4 ,,description4--,a remarkable blackish-grey rock4 ,although somewhat scoriaceous1 it has a sp4 gr4 of #bia4 ,it displays large phenocrysts of olivine and pyroxene1 #d to #h mm4 in size1 in a coarse-textured groundmass of stout felspars1 augite granules1 magnetite and a little glass4 ,the olivine is extensively hematised4 ,the pyroxene phenocrysts are of brownish-yellow augite with regular outlines and giving angles of extinction up to #dj4 ,the broad lamellar felspars of the groundmass1 which are on the average #c to #d mm4 long1 give extinctions indicating both acid labradorite 7#bc to #bh7 and medium andesine 7#af or #ag74 ,the abundant augite-grains average #je mm4 in size2 but the prism form occurs at times4 ,the species with felspar-lathes #c to #e mm4 long is alone represented4 #d4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 non-flu1 gran1 non-phen1 parv4 ,,characters4--,abundant olivine4 ,in the groundmass the felspar-lathes are not in flow-arrangement and the pyroxene is granular4 ,no plagioclase phenocrysts4 ,small phenocrysts of olivine and occasionally pyroxene under #b mm4 ,,description4--,a grey coarse-grained rock4 ,sp4 gr4 #bi4 ,it displays abundant small phenocrysts of olivine1 all less than a millimetre in size 7#b-h mm471 which are hematised in the fissures and at the borders4 ,the felspar-lathes1 which display a few twin-lamell giving extinctions of #af-ah 7medium andesine71 vary greatly in size4 ,the smaller are #a to #c mm4 and the larger #c to #e mm4 long2 but the two are connected by felspars of intermediate length4 ,the abundant augite granules average #jcg mm4 in breadth4 ,pyroxene phenocrysts are not represented in the slide4 ,from its coarsely crystalline texture this rock merits the field-name of a grey doleritic basalt2 and except in the arrangement of the felspar-lathes it does not differ from the grey doleritic basalts of genus #af4 #ab4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 non-flu1 oph1 non-phen1 parv4 ,,characters4--,olivine abundant4 ,felspars of the groundmass not in flow-arrangement4 ,pyroxene of the groundmass ophitic or semi-ophitic4 ,no plagioclase phenocrysts4 ,small phenocrysts 7under #b mm47 of olivine and occasionally a few of pyroxene4 ,,description4--,a dark greenish-brown rock1 with sp4 gr4 #bia1 showing abundant micro-porphyritic olivine in a groundmass consisting of ophitic pale-brown augite inclosing the felspar-lathes1 together with small olivines1 patches of magnetite1 and a little altered interstitial glass4 ,the olivine-phenocrysts are about #e mm4 in average size and are more or less hematised4 ,the felspar-lathes1 which average #ae mm4 in length1 often show twin-lamell that give extinctions of #bc-cj 7andesine-labradorite74 ,the species with felspar-lathes #a-b mm4 long is alone represented4 #ac4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 flu1 gran1 phen1 vitr4 ,,characters4--,olivine abundant4 ,felspars of the groundmass in flow-arrangement4 ,pyroxene of the groundmass granular4 ,phenocrysts of glassy plagioclase4 ,,description4--,dark grey or dark brown rocks with sp4 gr4 #bhh to #bii4 ,phenocrysts of olivine1 pyroxene1 and plagioclase occur in a groundmass showing partially parallel felspar-lathes1 abundant pyroxene grains1 and fine magnetite1 residual glass being scanty or absent4 ,the olivine-phenocrysts do not exceed #c or #d mm4 in size and in some rocks are less than #a mm4 ,they are usually more or less serpentinised and hematised at the borders and in the cracks2 but sometimes they are almost fresh and present regular outlines4 ,in some rocks the olivine also occurs as grains 7#c mm47 in the groundmass4 ,when the phenocrysts of olivine have blackish borders they are surrounded by a halo1 as though the crystal had attracted the magnetite from the groundmass immediately around4 ,the plagioclase phenocrysts vary from #a to #c mm4 in size4 ,they often contain abundant magma-inclusions and give lamellar extinctions of #ae to #be 7basic andesine74 ,in some rocks they are rudely parallel4 ,the pyroxene phenocrysts1 which are of pale brownish-yellow augite giving extinctions of over #cj1 do not usually exceed #c mm4 ,they present regular octagonal cross-sections and sometimes display lamellar twinning4 ,occasionally there is a suspicion of intergrowth with rhombic pyroxene4 ,the felspar-lathes1 which according to the species vary much in length1 at times show a few lamell4 ,the augite grains of the groundmass are abundant and are as a rule about #jb mm4 in size2 but in some rocks they are larger and in others smaller4 ,this genus may be divided into two sub-genera1 the porphyritic sub-genus where the felspar phenocrysts are larger than #c mm41 and the non-porphyritic where they are smaller4 ,all four species1 as indicated by the length of the felspar-lathes1 are represented4 #ad4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 flu1 gran1 phen1 opac4 ,,characters4--,olivine abundant4 ,felspars of the groundmass in flow-arrangement4 ,pyroxene of the groundmass granular4 ,opaque plagioclase phenocrysts4 ,,description4--,dark grey rocks1 with sp4 gr4 #bi to #bic1 showing phenocrysts of olivine and pyroxene with opaque whitish phenocrysts of plagioclase in a groundmass of felspar lathes1 pyroxene grains1 and magnetite1 with occasional fine olivine4 ,the olivine phenocrysts1 which are sometimes #e or #f mm4 in size1 are often deeply eroded4 ,they are at times so extensively hematised along the schiller-planes that they appear like brown mica4 ,the plagioclase phenocrysts owe their opacity in part to their consisting of an aggregate of lesser crystals which are clear and glassy and give lamellar extinctions of #bj to #cj 7andesine labradorite74 ,they do not usually exceed #c mm4 and are sometimes scanty4 ,the pyroxene phenocrysts1 which are at times infrequent1 may be #e mm4 in size4 ,they are of pale yellowish-brown augite1 giving extinctions of #dj4 ,the felspar-lathes are rarely lamellar2 but in one such case the angle of extinction was #ag 7medium andesine74 ,the grains of augite in the groundmass average #jb mm4 in diameter4 ,the only species represented is that with the felspar-lathes #a to #b mm4 long4 #ae4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 flu1 gran1 non-phen1 magn4 ,,characters4--,abundant olivine4 ,in the groundmass the felspars are in flow-arrangement and the pyroxene is granular4 ,no plagioclase phenocrysts1 but large phenocrysts1 over #b mm41 of olivine and pyroxene4 ,,description4--,this genus includes the most basic rocks represented in my collection4 ,they are compact heavy blackish rocks with sp4 gr4 #c to #ca1 and display large porphyritic crystals of olivine and pyroxene often #c or #d mm4 in size4 ,the olivine phenocrysts may be fairly fresh with clean outlines1 or they may be deeply eroded and stained by iron oxide1 or they may be passing into serpentine4 ,the pyroxene phenocrysts may be either eroded or possess regular outlines4 ,they are of pale brown augite and give extinctions over #cj4 ,the pyroxene granules1 which average #jb mm4 and are very abundant1 are of the same augite4 ,the felspar-lathes are relatively scanty4 ,in the two rocks here included they average in length #jf mm4 and #jh mm4 ,when lamell can be recognised they give extinctions of #cj-dj 7labradorite74 ,the untwinned lathes give extinctions of #bj-bh 7labradorite74 ,the only species represented is that with felspar-lathes less than #a mm4 in length4 #af4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 cop1 flu1 gran1 non-phen1 parv4 ,,characters4--,abundant olivine4 ,in the groundmass the felspar-lathes are in flow arrangement and the pyroxene is granular4 ,there are no plagioclase phenocrysts2 but there are numerous small phenocrysts1 under #b mm4 in size1 of olivine and occasionally a few of pyroxene4 ,,description4--,as a highly basic genus this ranks next to the preceding one1 the specific gravity of the rocks ranging from #bia to #cja4 ,all the four species indicated by the varying length of the felspar-lathes are represented in my collection4 ,the rocks of the first two1 with the felspars averaging less than #a mm4 and between #a and #b mm41 are compact aphanitic basalts1 only displaying an occasional small phenocryst of augite and blackish-grey or bluish-black in colour4 ,those of the last two species1 with the average length of the felspar-lathes #b-c mm4 and #c-e mm4 respectively1 are lightish-grey coarse-textured rocks of the doleritic type4 ,in all the rocks no pyroxene phenocrysts are displayed in the slide2 and the olivine phenocrysts1 which are very numerous1 do not usually exceed #a mm41 though occasionally the average size is #ac mm41 and not infrequently it is only #e mm4 ,in some cases where the larger olivine phenocrysts lie athwart the current of the felspar-lathes1 the smaller 7#e mm47 lie with their long axes parallel to the flow4 ,the olivine is either fresh1 or it may be beginning to serpentinise in the cracks1 or it may be in part hematised4 ,the crystals may have regular outlines1 or they may be rounded and sometimes deeply eroded4 ,the pyroxene granules of the groundmass are of pale-brown augite1 and average #ja to #jc mm4 in size4 ,occasionally a few prism forms occur1 giving extinctions of #cj to #dj4 ,in the case of the more compact rocks1 with the felspar-lathes averaging less than #b mm4 in length1 lamellar twinning is but scantily to be noticed in the lathes1 which give extinctions measured from the long axis of #bj to #be and by the twin lamell of #cj to #ce1 indicative of acid labradorite in both instances4 ,with the coarser doleritic grey basalts1 where the felspar-lathes are stouter and have an average length exceeding #b mm41 lamellar twinning is more frequent2 the extinctions afforded by the lamell range between #ae and #be 7medium andesine74 ,residual glass is scanty in these rocks1 and in the grey dolerites it is often difficult to recognise any4 #b4 ,,division ,,of ,,the ,,olivine-,,basalts ,,characters4--,scanty olivine4 ,,formula4--,oliv1 matr1 pauc4 #be4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 pauc1 non-flu1 gran1 phen1 vitr4 ,,characters4--,olivine scanty4 ,felspars 7lathes and prisms7 of the groundmass not in flow-arrangement4 ,pyroxene of the groundmass granular4 ,glassy plagioclase phenocrysts4 ,,description4--,about two-thirds of these rocks have a common facies1 being closely similar in appearance1 brownish-black in colour1 and with spec4 grav4 usually between #bhd and #bib4 ,they belong to the species with the felspar-lathes #a to #b mm4 in length4 ,they are essentially the rocks of the old submarine basaltic flows2 and they are often columnar1 the columns being #b to #d feet across4 ,my remarks will mainly apply to this predominant group4 ,to the eye they are somewhat compact and show scattered porphyritic crystals of plagioclase4 ,in the slide they display numerous phenocrysts of plagioclase1 with a few of olivine and pyroxene1 in a groundmass formed of stout lamellar felspar-lathes and small prisms forming a plexus with granular augite in the meshes4 ,there is a good deal of magnetite and generally scanty residual glass4 ,the plagioclase phenocrysts are usually #b to #c mm4 in size1 but they may be smaller 7#a to #b mm47 or larger 7#c to #e mm4 or more7 when the rock has a porphyritic appearance4#aaa ,they are often cross-macled and at times show zoning4 ,in many slides two kinds are distinguished by the extinctions which indicate in one case medium andesine 7#ae to #bb7 and in the other acid labradorite 7#bg to #cb74 ,they contain inclusions of the magma and are often eroded4 ,the pyroxene phenocrysts are of pale brown augite1 scanty and small1 and give extinctions of #cj to #dj4 ,they are sometimes twinned and may be eroded and contain inclusions of the magma4 ,the olivine phenocrysts1 which do not usually exceed #b or #c mm41 are mostly rounded1 but sometimes have the regular outlines1 and are in various stages of serpentinisation4 ,the felspars of the groundmass1 which average #ag mm4 in length1 are mostly stout and lamellar2 but they exhibit all transitions from the lathe-shape with one or two lamell to broad multi-lamellar prisms where the breadth is half the length4 ,they give lamellar extinctions averaging #ae to #ah 7andesine74 ,the augite granules of the groundmass are pale brown and average #jb to #jc mm4 in size4 ,in a few cases they are larger 7#je mm47 which is an indication of an approach to the ophitic type4 ,in most slides occur a few small augites of prism-form1 two or three times the size of the granules1 which give extinctions of over #cj4 ,where the phenocrysts of augite are very scanty or absent1 there exist large grains 7#a mm47 of an intermediate size4 ,the magnetite is often abundant1 occurring in crystals1 rods1 and irregular masses1 the last associated often with the interstitial glass which is present in small quantities in most rocks1 being greenish or brownish and showing fibrous devitrification4 ,in some localities semi-vitreous rocks referable to this genus are frequent4 ,this is especially the case in the ,naivaka peninsula1 where the rocks show a fair amount of glass in the groundmass1 the porphyritic augite being well developed1 whilst the pyroxene of the groundmass is only in part differentiated4 ,three of the four species are here represented4 ,those with large felspar-lathes 7#b-c mm4 long7 and coarse augite granules 7#je7 approach the semi-ophitic rocks included in genus #cc4 #bf4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 pauc1 non-flu1 gran1 phen1 opac4 ,,characters4--,olivine scanty4 ,in the groundmass the felspar-lathes and prisms are not in flow-arrangement and the pyroxene is granular4 ,the plagioclase phenocrysts are opaque4 ,,description4--,dark grey porphyritic rocks1 which1 from the opacity of the felspar phenocrysts1 look like porphyrites4 ,they are not very frequent and occur mostly on the northern slopes of ,mount ,seatura4 ,two different types occur in my collection which may be regarded as sub-genera4 ,in the most basic kind1 where the sp4 gr4 is #bhf to #bhi1 the plagioclase phenocrysts1 #b to #c mm4 in size1 owe their opacity chiefly to their aggregate structure4 ,they give lamellar extinctions 7#ae-cj7 of andesine labradorite4 ,porphyritic olivine is scanty and more or less hematised2 but a fair amount of olivine grains1 less than #a mm41 occur in the groundmass4 ,pyroxene phenocrysts are scanty1 but microporphyritic pale brown augite 7#a mm47 is frequent4 ,in the groundmass are found stoutish felspar-lathes1 averaging #b mm4 long1 together with an abundance of fine augite granules 7#ja-jb mm47 and fine magnetite1 the residual glass being scanty4444 ,in the other type the sp4 gr4 is #bge2 and the plagioclase phenocrysts #d to #f mm4 in size give extinctions of andesine and acid labradorite 7#aj-cj74 ,there is an approach to the orthophyric structure in the groundmass1 as is indicated by the number of short broad felspars1 averaging #b mm4 in length and giving lamellar extinctions of acid and basic andesine4 ,the granular augite of the groundmass is coarse 7#jd mm471 and occasional prism-forms give extinctions of #dj4 #cc4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 pauc1 non-flu1 oph1 phen1 vitr4 ,,characters4--,olivine scanty4 ,in the groundmass the felspar-lathes are not in flow-arrangement and the pyroxene is ophitic or semi-ophitic4 ,plagioclase phenocrysts glassy4 ,,description4--,these brownish-black rocks are all of the semi-ophitic type4 ,although no ophitic 8plates0 occur in the slide1 the augites of the groundmass have no longer the granular form1 but are large1 #jh-a mm4 in size1 and tend to invest the felspar-lathes4 ,the specific gravity ranges from #bgh to #bhf4 ,as in other of the ophitic and semi-ophitic rocks of this collection 7genera #i1 #aj1 #ab1 of the augite-andesites71 the large size of the felspar-lathes 7#b-c mm4 long7 of the groundmass gives a doleritic texture in the slide4 ,in most of the other characters these rocks approach those of genus #be which possess felspar-lathes more than #b mm4 in length4 ,but they are more often semi-vitreous1 and display a considerable amount of dark smoky glass showing numerous magnetite rods and skeletal crystals with fibrous devitrification4 ,the plagioclase phenocrysts1 which vary much in size in different rocks 7in some #b or #c mm41 in others #d or #e mm471 give extinctions of andesine labradorite 7#bj-ce74 ,they are often eroded and contain numerous large black inclusions of the magma4 ,the pyroxene phenocrysts1 which are of pale-brown augite1 often have an aggregate-structure1 having been formed in situ4 ,others again consist of single crystals and have been much affected by the magma4 ,the olivine phenocrysts1 which are at times deeply eroded1 are generally small and in part serpentinised4 #cg4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 pauc1 flu1 gran1 phen1 vitr4 ,,characters4--,olivine scanty4 ,in the groundmass the felspar-lathes are in flow-arrangement and the pyroxene is granular4 ,glassy plagioclase phenocrysts4 ,,description4--,brownish-black rocks which cannot be distinguished1 except in the flow-arrangement of the felspars of the groundmass1 from those described under genus #be4 ,like them they enter into the formation of the basaltic plains of ,sarawanga and ,mbua and elsewhere4 ,most of the rocks of this genus group themselves into one type where the felspar-lathes average in length #ae-ba mm4 ,the sp4 gr4 is usually between #bhg and #bia4 ,though rarely porphyritic1 such rocks display to the eye a few small scattered glassy phenocrysts of plagioclase and an occasional grain of olivine4 ,it is to this type of the genus that the following description applies4 ,in the thin sections they display small plagioclase phenocrysts1 with a few of olivine and occasionally of pyroxene1 in a groundmass where the flow-arrangement of the felspar-lathes is well marked1 the rest of the groundmass being made up of granular augite with magnetite and generally a little residual glass4444 ,the plagioclase phenocrysts do not usually exceed #b mm4 in size and contain magma inclusions4 ,two kinds are often indicated in the same slide by the extinctions1 namely1 one of medium andesine 7#ag-bb71 and the other of acid labradorite 7#bh-cc74444 ,the pyroxene phenocrysts are of pale brown augite2 but they are small 7less than #b mm471 scanty1 and often absent when their place is taken by microporphyritic augite1 #b mm4 in size4444 ,the olivine phenocrysts are generally small4 ,though sometimes showing the long hexagonal sections1 they are often rounded and more or less serpentinised4444 ,the felspars of the groundmass present more typical lathes than are to be observed in the non-parallel felspars of the rocks of genus #be4 ,the twin-lamell1 when present1 are fewer2 but give similar extinctions 7#ae-ba7 of medium andesine4444 ,the augite granules are1 as a rule1 #jb or #jc mm4 in diameter2 but occasional more prismatic forms occur1 two or three times the length1 which give extinctions of over #cj4 ,the magnetite is abundant1 and the scanty interstitial glass is green or brown and displays fibrous devitrification4 ,the following three species1 as indicated by the length of the felspar-lathes1 are represented in my collection3 7a7 #jb-a mm4 7b7 #a-b mm4 7c7 #b-c mm4 #ch4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 pauc1 flu1 gran1 phen1 opac4 ,,characters4--,olivine scanty4 ,in the groundmass the felspar-lathes are in flow-arrangement and the pyroxene is granular4 ,opaque plagioclase phenocrysts4 ,,description4--,grey rocks1 sp4 gr4 #bgh to #bhc1 showing small opaque porphyritic crystals of plagioclase with a few phenocrysts of olivine and pyroxene in a groundmass of parallel felspar-lathes1 augite granules1 and magnetite1 with very scanty1 if any1 interstitial glass4444 ,the plagioclase phenocrysts1 #b to #c mm4 in size1 are often aggregates of smaller crystals4 ,they contain colourless granular inclusions and are sometimes zoned1 giving extinctions of medium andesite 7#ae-ah71 and of andesine labradorite 7#be-bi74444 ,the pyroxene phenocrysts are pale-brown1 scanty1 #b to #c mm4 in size1 often twinned and give the large extinctions of augite4444 ,the olivine phenocrysts1 which do not exceed #b or #c mm41 are deeply eroded by the magma and are hematised and schillerised4 ,small grains also occur in the groundmass4444 ,the felspar-lathes1 which in the species here represented average #ae mm4 in length1 are stout and give lamellar extinctions of andesine 7#ah-bb74444 ,the augite granules are pale-brown and usually #jb-jc mm4 in diameter4 ,the only species represented in my collection is that with the felspar-lathes #a-b mm4 long4 #dj4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 pauc1 flu1 gran1 non-phen1 parv4 ,,characters4--,olivine scanty4 ,in the groundmass the felspar-lathes are in flow-arrangement and the pyroxene is granular4 ,no plagioclase phenocrysts2 but there are a few small phenocrysts of olivine and sometimes of pyroxene under #b mm4 in size4 ,,description4--,compact-looking non-porphyritic blackish-brown rocks1 sp4 gr4 about #bi4 ,occasionally a little vesicular4 ,for the most part dyke-rocks4 ,in the slide are displayed a few small phenocrysts of olivine and pyroxene in a groundmass formed of more or less parallel felspar-lathes1 augite granules1 magnetite1 sometimes in rods1 and a little greenish devitrified residual glass4444 ,the pyroxene phenocrysts are of pale-brown augite and are generally less than a millimetre in size4 ,they may be single crystals or they may be formed of an aggregate of a few smaller crystals4444 ,the olivine phenocrysts rarely exceed #b mm4 in size and are in part serpentinised4444 ,the augite granules vary usually from #ja to #jc mm4 in diameter4444 ,the felspar-lathes of the rocks in this collection are large1 often exceeding #b mm4 in length1 giving the rock a doleritic texture in the slide4 ,in a single slide they may range from #a to #f mm4 ,when lamellar they give extinctions of #ae to #be 7basic andesine74 ,two species are represented in this collection3-- 7a7 with felspar-lathes #b-c mm4 7b7 with felspar-lathes #c-e mm4 #dd4 ,,genus ,,of ,,the ,,olivine-,,basalts ,,formula4--,oliv1 matr1 pauc1 flu1 prism1 non-phen1 parv4 ,,characters4--,olivine scanty4 ,in the groundmass the felspar-lathes are in flow-arrangement and the pyroxene is in great part prismatic4 ,there are no phenocrysts of plagioclase2 but there are a few small phenocrysts of olivine and sometimes of pyroxene1 less than #b mm4 in size4 ,,description4--,a dark grey compactish rock2 sp4 gr4 #bi2 showing a little macroscopic olivine2 forming a dyke in the tuffs on the summit of the hill of ,vatui 7p4 #ed74 ,in the section it exhibits a few phenocrysts of olivine 7more or less serpentinised7 and of augite in a groundmass formed of stout augite prisms and small augite granules with felspar-lathes1 magnetite1 and a little devitrified yellowish interstitial glass4 ,the augite prisms and the felspar-lathes are in flow-arrangement4444 ,the pyroxene phenocrysts1 which are pale brown and give extinctions of over #cj from the single cleavage-lines1 may be aggregates of five or six smaller crystals or single crystals presenting sometimes lamellar twinning4 ,the first are doubtless formed in situ4 ,the second though showing regular outlines may have a nucleus giving a different extinction and possessing eroded margins4 ,the stout augite prisms of the groundmass1 which are occasionally twinned1 have an average length of #b to #c mm4 and give angles of extinction with the long axis of #cj to #dj4 ,the felspar-lathes average only #jg mm4 in length and afford extinctions1 when untwinned1 of #ah to #bd 7acid labradorite74 ,the only species represented is that where the average length of the felspar-lathes is between #jb and #a mm4 ,,chapter ,,xix ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,,augite ,,class ,,sub-,,class ,,ii ,,augite-,,andesites ,,including ,,the ,,basaltic ,,andesites 7,plag1 aug1 matr47 ,,this sub-class1 which comprises #dj per cent4 of the volcanic rocks1 is characterised by the absence of olivine on the one hand1 and by the rarity or absence of rhombic pyroxene on the other4 ,on the basic side it shades into the olivine-basalts through the basaltic andesites1 and on the acid side by intermediate stages into the hypersthene augite andesites2 and for these reasons it is not always possible to draw a sharp line of distinction4 ,in cases where a hand-specimen displays no macroscopic olivine and where a solitary small phenocryst of olivine is alone observed in the slide1 it should be referred to this sub-class2 and here also all doubtful specimens as regards the occurrence of olivine should be placed4 ,when the question of the occurrence of rhombic pyroxene arises1 it should be remembered that the great prevalence of monoclinic pyroxene amongst the phenocrysts and the practical absence of rhombic pyroxene from the groundmass are essential characteristics of this sub-class4 ,rhombic pyroxene is only indicated at times by intergrowths in the phenocrysts4 ,the basaltic andesites enter into the formation of old 8flows10 as in the ,mbua and ,ndama plains4 ,the other rocks enter principally into the composition of dykes1 necks1 and agglomerates4 ,i4 ,,granular ,,sub-,,order 7,,augite-,,andesites7 ,,formula4--,aug1 matr1 non-flu1 gran4 #a4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 non-flu1 gran1 phen1 vitr4 ,,characters4--,in the groundmass the felspar-lathes and prisms are not in flow-arrangement and the augite is granular4 ,phenocrysts of glassy plagioclase4 ,,description4--,these rocks frequently form dykes2 and it is probable that most of the instances where the nature of the exposure could not be ascertained also fall into this category4 ,they are dark-brown or blackish1 and their sp4 gr4 ranges1 except in the semi-vitreous rocks1 from #bg to #bhc4 ,they are sometimes vesicular1 and rocks with abundant interstitial glass are common4 ,they admit of grouping into two sub-genera according to the size of the plagioclase phenocrysts3 7a7 ,porphyritic1 where the average size is #c mm4 or over4 7b7 ,non-porphyritic where the average size is less than #c mm4 ,nearly all the rocks in my collection belong to the second group4 ,in the sections they display phenocrysts of plagioclase and occasionally of pyroxene in a groundmass formed of a plexus of felspar-lathes1 augite granules1 magnetite1 and usually a fair amount of smoky more or less opaque interstitial glass4444 ,the felspar phenocrysts1 which are sometimes abundant1 give lamellar extinctions of andesine labradorite 7#ae to #cj74 ,they are frequently small 7#a to #b mm47 and contain often many magma-inclusions4 ,whilst the corroded aspect of some indicate that they belong to an earlier period1 the aggregate character and regular outlines of others suggest that they have been produced in position4444 ,pyroxene phenocrysts are absent in half the rocks4 ,when present they are generally small and of a pale augite which gives extinctions of #cj4 ,their size does not usually exceed #b mm42 and they may consist of single crystals 7sometimes twinned7 or of an aggregate of smaller crystals4 ,at times there is a suspicion of intergrowth with rhombic pyroxene2 but no phenocrysts formed alone of that mineral occur4444 ,the augite granules of the groundmass as a rule vary from #jb to #jd mm4 in diameter4 ,occasional prism-forms giving large extinctions occur4444 ,the felspar-lathes vary much in length in different rocks4 ,in some they average as little as #je mm41 and in others as much as #b mm42 but the doleritic type with yet longer lathes is not represented in the collection except among the altered rocks4 ,most of the lathes show a single median twin-line1 and when broader they display twin-lamell4 ,the angles of extinction indicate acid and basic andesine4 ,three out of the eight species distinguished by the length of the felspar-lathes occur in my collection1 that with the longest lathes 7#c-e mm47 being not represented4 #b4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 non-flu1 gran1 phen1 opac4 ,,characters4--,in the groundmass the felspar-lathes and prisms are not in flow-arrangement and the augite is granular4 ,opaque plagioclase phenocrysts4 ,,description4--,this genus may be divided into two groups according to the size of the plagioclase phenocrysts1 the first 8porphyritic10 where they average #c mm4 and over1 the second 8non-porphyritic10 where they are smaller than #c mm41 usually not over #b mm4 ,the former would include some of the 8porphyrites10 and to this only one of the rocks sliced is to be referred4 ,all the rest belong to the non-porphyritic type2 and several of them are rocks that have undergone the propylitic change1 as indicated by the formation of pyrites1 chlorite1 calcite1 and other alteration-products4 7a7 ,,porphyritic ,,sub-,,genus4--,a greyish rock1 with sp4 gr4 #bgh1 showing abundant porphyritic opaque plagioclase 7#d to #g mm471 from the vicinity of ,satulaki4 ,these phenocrysts are often aggregates of lesser crystals1 or they may be extensively cross-macled4 ,they are traversed by numerous fine cracks and show much dust-like included material4 ,they are in part corroded by the magma and give evidence of fracture in their present position1 the re-union being sometimes effected by the growth of new substance4 ,their lamellar extinctions 7#aj to #bj7 are those of andesine4 ,the groundmass displays a plexus of stout felspar-lathes1 averaging #a mm4 long1 with the meshes occupied by coarse augite granules1 #jc to #je mm41 with little1 if any1 interstitial glass4 ,the felspars are often lamellar and give extinctions like those of the phenocrysts4 7b7 ,,non-,,porphyritic ,,sub-,,genus4--,reference will first be made to some of the propylitic rocks of the dykes of the ,ndriti ,basin which belong to this group 7see p4 #gj74 ,they are greenish or greyish1 with sp4 gr4 #bgf to #bh1 and often sparkle with pyrites and contain secondary calcite1 sometimes to such an extent that they might be taken at first sight for impure limestones4 ,the small opaque plagioclase phenocrysts 7under #b mm471 that they contain1 are more evident in the slide than in the hand-specimen1 and scarcely give a macroscopic character to the rock4 ,they give extinctions 7#aj to #cj7 ranging from those of acid andesine to acid labradorite1 and are traversed by numerous cracks occupied by calcitic and other alteration products4 ,the few pyroxene phenocrysts that once existed are now entirely represented by chloritic pseudomorphs4 ,the groundmass displays a doleritic texture1 exhibiting a plexus of long felspar-lathes1 #b to #d mm4 in average length1 which often present a false resemblance to a flow-arrangement from their aggregation into bundles4 ,they are often clouded by secondary products1 but occasionally give lamellar extinctions 7#bj to #cj7 indicating andesine labradorite4 ,the rest of the groundmass is greatly altered1 the granular augite and the interstitial glass1 which originally existed in fair amount1 being replaced by calcite1 chlorite1 pyrites1 and occasionally epidote1 so that the rock mass appears largely impregnated with alteration products4 ,in addition there is much secondary magnetite1 and in some cases there are a few minute cavities filled with chalcedonic silica and zeolites4 ,reference may here be made to a singular rock from ,ruku-ruku ,bay1 which resembles the ,ndriti rocks in its propylitic alteration1 but the felspar-lathes of the groundmass1 #ba mm4 in length1 give the small extinctions of oligoclase4 ,spec4 grav4 #bfa4 ,most of the prevailing rocks of ,mount ,freeland belong to this sub-genus4 ,they are dark grey and show small opaque plagioclase phenocrysts #a or #b mm4 in size4 ,they usually1 however1 are more or less altered1 the change being often of the propylitic type1 calcite1 chloritic material1 viridite1 and occasionally pyrites occurring as alteration products4 ,the specific gravity of the altered rocks is #bfa-bfi2 that of the least affected is about #bgf4 ,they all1 however1 belong to the same genus1 displaying small phenocrysts of plagioclase and augite in a groundmass composed of minute stoutish felspar-lathes 7#jc-jf mm471 augite granules1 magnetite1 and a little residual glass4 ,the plagioclase phenocrysts owe their opacity partly to the numerous fine cracks traversing them and partly to the alteration products4 ,the pyroxene phenocrysts1 which are mostly of pale yellow augite1 display at times intergrowths of rhombic pyroxene4 #d4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 non-flu1 gran1 non-phen1 parv4 ,,characters4--,in the groundmass the felspar-lathes and prisms are not in flow-arrangement and the augite is granular4 ,there are no plagioclase phenocrysts1 and those of augite when present are small 7under #b mm474 ,,description4--,two groups of these rocks occur in my collection4 ,in the one there are vesicular and scoriaceous rocks forming dykes near ,nukunase and near the village of ,ndriti4 ,they display a plexus of felspar-lathes with abundant smoky more or less devitrified glass1 the augite granules not being always differentiated4 ,the felspar-lathes vary from #a to #b mm4 in average length1 and when lamellar give extinctions of basic andesine 7#be74 ,there are no pyroxene phenocrysts1 and the augite granules when present average #jb mm4 in size4 ,in the other group are included some propylites from the dykes of the ,ndriti ,basin4 ,they are greyish or greenish rocks1 have a sp4 gr4 of #bgb to #bgf1 sparkle often with pyrites1 and contain so much secondary calcite that they effervesce freely with an acid4 ,except in the rarity or absence of plagioclase phenocrysts1 they come near to the propylitic rocks described under genus #b4 ,they usually display a doleritic groundmass exhibiting long felspar-lathes1 #b to #cc mm4 in length1 which present the same pseudo-flow arrangement from their being gathered into bundles4 ,the alteration corresponds precisely to that previously described1 chlorite1 epidote1 pyrites1 c41 occurring in quantity as secondary products4 ,,ii ,,prismatic ,,sub-,,order ,,of ,,the ,,augite-,,andesites ,,where ,,the ,,felspar-,,lathes ,,are ,,not ,,in ,,flow-,,arrangement ,,formula4--,aug1 matr1 non-flu1 prism4 ,the augite-andesites1 which display in the groundmass a plexus of felspar-lathes and much prismatic pyroxene1 are not frequent in my collection4 ,about half of the specimens belong to agglomerates1 whilst the rest are of the massive type1 none apparently being obtained from dykes4 ,they admit of the same classification as that generally adopted for the 8granular0 sub-orders2 and it must be not forgotten that granular pyroxene also occurs but is not predominant4 #e4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 non-flu1 prism1 phen1 vitr4 ,,characters4--,in the groundmass the felspar-lathes and prisms are not in flow-arrangement and the augite is for the most part prismatic4 ,plagioclase phenocrysts glassy4 ,,description4--,except as regards the prismatic pyroxene these rocks do not differ much from the 8granular0 augite-andesites4 ,those before me show phenocrysts of plagioclase and sometimes of augite in a groundmass displaying a mesh-work of felspar-lathes1 prismatic pyroxene1 and much interstitial glass4444 ,the plagioclase phenocrysts1 #a to #c mm4 in size1 show abundant magma-inclusions arranged either zone-wise or parallel to the twinning-planes4 ,they are often eroded4444 ,the phenocrysts of augite1 which give extinctions of over #cj1 are often rounded and display glass and other inclusions4444 ,the prismatic pyroxenes of the groundmass vary in average length from #jc to #jh mm4 ,they have the peculiar pale muddy brown hue characteristic of the prismatic augite in these rocks1 and give oblique extinctions up to #cj and over4 ,they may be short and broad or long and slender1 and when there is much glass in the rock they resemble the felspar-lathes in their forked and imperfect extremities4 ,granular pyroxene occurs1 but is subordinate4444 ,the felspar-lathes1 #a mm4 long1 are rarely lamellar1 and give extinctions measured from their long axis of #bj 7basic andesine74 #f4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 non-flu1 prism1 phen1 opac4 ,,characters4--,in the groundmass the felspar-lathes are not in flow-arrangement and the augite is for the most part prismatic4 ,the plagioclase phenocrysts are opaque4 ,,description4--,light and dark grey rocks displaying abundant opaque plagioclase phenocrysts not exceeding #be mm4 ,they are somewhat altered1 one of the specimens having a sp4 gr4 of #bfh4 ,in the section they exhibit phenocrysts of plagioclase1 and occasionally of augite in a groundmass of felspar-lathes1 pyroxene prisms and granules 7the former predominating71 with a fair amount of altered interstitial glass4444 ,the plagioclase phenocrysts owe their opacity to the great number of fine and sometimes parallel cracks filled with alteration products1 that traverse them4 ,although much of their original material has often disappeared1 they still display the lamellar twinning of medium andesine 7#ae to #bj74444 ,the phenocrysts of pale yellowish augite1 which give the large extinctions of that mineral1 exhibit but little alteration1 although lying in the same slide with those of the plagioclase4444 ,the pyroxene prisms of the groundmass are of the same yellowish augite4 ,they are broad with rounded extremities and are arranged in a loose plexus4444 ,the felspars of the groundmass1 which average #a mm4 in length and give extinctions of medium andesine1 are either lathe-shaped or short and broad when they display lamell4 ,the last-named approach the orthophyric type1 and such rocks come near the porphyrites2 but ,i do not feel justified in placing them in a separate orthophyric order4 ,,iii ,,ophitic ,,sub-,,order ,,of ,,the ,,augite-,,andesites ,,with ,,the ,,felspars ,,of ,,the ,,groundmass ,,not ,,in ,,flow-,,arrangement4 ,,formula4--,aug1 matr1 non-flu1 oph4 ,these rocks form generally ancient flows4 ,they are for the most part semi-ophitic1 large ophitic 8plates0 being uncommon4 #i4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 non-flu1 oph1 phen1 vitr4 ,,characters4--,the felspar-lathes and prisms of the groundmass are not in flow-arrangement4 ,the augite of the groundmass is ophitic or semi-ophitic4 ,glassy plagioclase phenocrysts4 ,this genus may be divided into two sub-genera1 7a7 ,porphyritic1 where the average size of the plagioclase phenocrysts is #c mm4 and over4 7b7 ,non-porphyritic1 where the size is less than #c mm4 ,a4 ,,porphyritic ,,sub-,,genus ,,description4--,coarse-looking brownish-black porphyritic rocks displaying large plagioclase crystals that often show a play of colours4 ,their sp4 gr4 is about #bh4 ,none of the rocks in my collection are vesicular4 ,on account of the considerable porphyritic development of the plagioclase1 the groundmass is relatively diminished1 the large phenocrysts occupying about a third of the mass4 ,they form ancient basaltic flows more especially in the vicinity of the isolated hills and mountains of acid andesite1 as around ,vatu ,kaisia2 whilst they may enter into the formation of the low basaltic plains as in the region west and south of the ,ndreketi ,river4 ,they are1 however1 limited in their extent and occurrence4 ,from the large amount of glass in the groundmass1 they may be inferred to belong to flows formed under different conditions from those under which the great basaltic plateaux were formed1 where the rock contains but scanty interstitial glass4 ,in the slide they show the large plagioclase phenocrysts together with a few small plates of ophitic augite in a groundmass displaying in an abundant smoky glass a loose plexus of long stout lathe-like plagioclase prisms partly wrapped around by lesser augites4444 ,the plagioclase phenocrysts1 which attain a size of #d to #f mm41 give lamellar extinctions of basic andesine 7#bj-bg7 and show concentric zone-lines with transmitted light4 ,they often polarise in brilliant colours and are extensively cross-macled4 ,they contain usually abundant inclusions of the magma sometimes arranged zone-wise1 and are frequently eroded4444 ,non-ophitic pyroxene phenocrysts are uncommon4 ,in the slide occur one or two small 8plates10 #a to #b mm4 in size1 of ophitic pale-brown augite1 and a number of lesser augites1 #b to #c mm4 in size1 which in part wrap around the felspar-lathes and by their aggregation form imperfect ophitic 8plates40444 ,the long stout felspar-lathes1 which are on the average #c to #de mm4 in length1 give lamellar extinctions of #ae to #bj 7medium andesine74444 ,the copious smoky glass is rendered partially opaque by the abundant development of rods and skeletal crystals of magnetite1 and shows the fibrous devitrification arising from the formation of incipient microliths4 ,in some rocks there appear in the smoky glass brownish-yellow patches of the residual magma which under the microscope cannot be distinguished from palagonite4 ,all but one of the specimens belong to the species where the felspar-lathes average over #c mm4 in length4 ,b4 ,,non-,,porphyritic ,,sub-,,genus ,,description4--,blackish-brown semi-ophitic rocks1 sp4 gr4 #bgd-bgg1 frequently of doleritic texture and showing a few small macroscopic plagioclase phenocrysts4 ,they are sometimes vesicular1 and form old flows in a few localities1 as in the vicinity of ,natua in the eastern part of the ,ndreketi plains and in the coast district between ,lekutu and ,wailea ,bay4 ,they display in the slide small plagioclase phenocrysts1 often abundant1 in a groundmass exhibiting a loose plexus of large lathe-shaped felspar prisms1 together with occasional small ophitic 8plates0 of augite and numerous smaller semi-ophitic augites1 whilst there is much interstitial smoky glass4444 ,the plagioclase phenocrysts are as a rule #a to #b mm4 in size and do not exceed #c mm4 ,they often contain abundant inclusions of the magma sometimes arranged schiller-fashion1 and are frequently eroded4 ,their lamellar extinctions 7#ae-cj7;indicate andesine labradorite4444 ,the stout plagioclase lathes1 which in most of my specimens range between #b and #c mm41 and contain at times magma-inclusions1 give the rocks their doleritic texture4444 ,the occasional small ophitic 8plates0 of pale augite are not over #a mm4 in size and give extinctions of #cj from the single cleavage-lines4 ,the lesser augites1 #b mm4 in size1 are several times larger than typical granular pyroxenes 7#jb-jc mm471 and adapt their form to the interspaces of the felspar-lathes which they in part invest4444 ,the copious interstitial glass is generally smoky and sometimes quite opaque through the deposition of magnetite4 ,it is never clear and isotropic1 but displays fibrous devitrification and is usually a little altered4 ,these rocks come near to those of the previous sub-genus in several respects1 but they differ conspicuously in their non-porphyritic character1 in being sometimes vesicular1 and in their general appearance4 ,all the four species indicated by the length of the felspar-lathes are here represented2 but the doleritic types with the lathes exceeding #b mm4 are the most frequent4 #aj4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 non-flu1 oph1 phen1 opac4 ,,characters4--,in the groundmass the felspar-lathes and prisms are not in flow-arrangement and the augite is ophitic or semi-ophitic4 ,the plagioclase phenocrysts are opaque4 ,this genus may be divided into two sub-genera1 porphyritic and non-porphyritic1 according to the average size of the plagioclase phenocrysts1 whether above or below #c mm4 ,a4 ,,porphyritic ,,sub-,,genus4--,this is represented by a light grey porphyritic rock1 with sp4 gr4 #bge1 from the lower part of ,mount ,freeland4 ,it comes near to the porphyrites1 and displays large opaque white phenocrysts of plagioclase #e or #f mm4 long4 ,it is a somewhat altered rock4 ,in the thin section it displays the plagioclase phenocrysts in a ground mass of doleritic and semi-ophitic texture showing a plexus of long felspar-lathes partly invested by small augites with a fair amount of altered greenish opaque interstitial glass4444 ,the plagioclase phenocrysts1 which give extinctions of #aa to #ae 7acid andesine71 are traversed by a network of fine cracks and contain a quantity of colourless dust-like inclusions and alteration-products4 ,they are long and rectilinear in outline and are not much affected by the magma4444 ,the felspar-lathes1 which average #bf mm4 in length1 are occasionally lamellar when the angle of extinction indicates acid andesine4 ,like the phenocrysts they contain many dust-like inclusions4444 ,the augite may at times form an aggregate phenocryst of small size2 but usually it occurs as semi-ophitic masses #a mm4 in diameter4 ,b4 ,,non-,,porphyritic ,,sub-,,genus4--,the specimen representing this group is a coarse-grained greyish altered rock1 sp4 gr4 #bha1 found in blocks near ,waikatakata 7p4 #bjd71 showing small somewhat opaque plagioclase phenocrysts4 ,in the section these phenocrysts are displayed in numbers together with a few of augite4 ,the groundmass1 doleritic in texture in this species1 displays a plexus of long stout felspar-lathes with numerous semi-ophitic lesser augites1 chloritic pseudomorphs after pyroxene1 and scanty interstitial altered glass4444 ,the plagioclase phenocrysts1 #b to #c mm4 in size1 give extinctions 7#bb to #bh7 of basic andesine4 ,they are traversed by many fine cracks and contain an abundance of colourless dust-like inclusions1 apparently altered magma products4444 ,the small pyroxene phenocrysts consist of aggregates of smaller crystals of pale augite4 ,the lesser augites1 #a mm4 in size1 partly invest the felspars4444 ,the broad felspar-lathes1 which average #be mm4 in length and give lamellar extinctions of medium andesine 7#ae71 contain inclusions similar to those of the phenocrysts4444 ,the scanty interstitial glass is converted into viriditic and chloritic materials4 ,secondary calcite also occurs here and in the chloritic pseudomorphs4 ,the only species represented is that with felspar-lathes #b to #c mm4 in length4 #ab4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 non-flu1 oph1 non-phen1 parv4 ,,characters4--,in the groundmass the felspar lathes and prisms are not in flow-arrangement and the augite is ophitic or semi-ophitic4 ,no plagioclase phenocrysts4 ,augite phenocrysts when present less than #b mm4 in size4 ,,description4--,these rocks come near to the non-porphyritic group of genus #i2 but differ in the absence or rarity of plagioclase phenocrysts1 in their more frequently vesicular and scoriaceous character1 and in the fresher condition of the rock4 ,their sp4 gr4 is about #bgg4 ,they present themselves usually as blackish-brown doleritic rocks and form ancient flows in the coast-plains1 sometimes exhibiting a columnar structure as in the crossing of the ,ndreketi above ,mbatiri4 ,they are1 however1 of limited occurrence and are mostly represented in the ,ndreketi plains and in the district between the ,lekutu ,river and ,wailea ,bay4 ,typically they display in thin sections no phenocrysts either of plagioclase or of pyroxene1 and exhibit a plexus of usually long stout felspar-lathes partly invested by the lesser augites in a copious smoky glass4444 ,the felspar-lathes1 #be to #d mm4 in length1 give lamellar extinctions of #aj to #bj 7andesine7 and contain a few magma-inclusions4444 ,the semi-ophitic augites1 #a to #b mm4 in size1 are sometimes twinned4444 ,the smoky glass polarises feebly and displays dark feathery aggregates of microliths4 ,within it are brownish-yellow semi-opaque patches of residual glass1 which polarise faintly and behave like palagonite4 ,the two species with felspar-lathes #b to #c mm4 and #c to #e mm4 are represented in my collection4 #d4 ,,granular ,,sub-,,order ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 flu1 gran4 #ac4 ,,genus ,,formula4--,aug1 matr1 flu1 gran1 phen1 vitr4 ,,characters4--,in the groundmass the felspar-lathes or prisms are in flow-arrangement and the augite is granular4 ,the plagioclase phenocrysts are glassy4 ,,description4--,this genus readily splits up into two sub-genera1 the non-porphyritic1 where the plagioclase phenocrysts are less than #c mm4 in size1 and the porphyritic where they are larger4 #a4 ,,non-,,porphyritic ,,sub-,,genus4--,dark-brown or blackish rocks displaying small plagioclase phenocrysts1 usually only #a or #b mm4 in size4 ,three of the four species defined by the length of the felspar-lathes are represented in my collection4 ,,species ,a4--,felspar-lathes 4#jb-4a mm4 in average length4 ,this may again be sub-divided according to the degree of basicity of the rocks3-- 7a7 ,sub-species of greater basicity4--,sp4 gr4 #bgf to #bhb4444 ,such rocks are represented in dykes and in the prevailing basic agglomerates4 ,they are at times scoriaceous4 ,the small plagioclase phenocrysts1 which are fairly numerous1 give lamellar extinctions of andesine labradorite 7#bj to #cj74 ,two kinds occur which may or may not be represented in the same slide4 ,in the one the crystal is much corroded and contains abundant magma-inclusions4 ,it belongs in such a case to an earlier period4 ,in the other the outlines are clean and regular1 and the crystal is often cross-macled to such an extent that it may be inferred from its unbroken condition to have been formed in situ4 ,augite phenocrysts when present are small and scanty1 pale-yellow1 idiomorphic1 and giving extinctions of #cj4 ,the felspar-lathes1 which average #jf-jh mm4 in length1 give extinctions indicating andesine labradorite4 ,the augite granules are small 7#ja-jb mm474 ,interstitial glass1 generally scanty1 is sometimes abundant when it is smoky1 showing fibrous devitrification1 with irregular 8lacun0 filled with a brownish yellow opaque glass like palagonite4 7b7 ,sub-species of lesser basicity4--,sp4 gr4 #bfe-bgj4444 ,the remarks on the plagioclase phenocrysts of the more basic sub-species here apply1 except that the lamellar extinctions indicate medium andesine 7#ab-bj74 ,the characters of the augite phenocrysts and granules are in both groups the same2 but in this case there is more frequently a suspicion of intergrowth with rhombic pyroxene4 ,the felspar-lathes are very small1 #jd or #je mm1 and give simple extinctions of acid andesine 7#e-aj74 ,interstitial glass exists in moderate amount4 ,,species ,b4--,felspar-lathes #a-b mm4 in average length4 ,blackish or dark-grey rather compact rocks1 sp4 gr4 #bge-bgi1 that cannot be readily divided into groups according to their basicity4 ,they form dykes and volcanic 8necks0 and are sometimes scoriaceous4 ,the small plagioclase phenocrysts1 which are most evident in the slide1 present the two kinds above described under ,species ,a4 ,they give lamellar extinctions varying from those of medium andesine to acid labradorite 7#ae-cj74 ,the augite phenocrysts1 which are small and scanty1 occasionally show intergrowths of rhombic pyroxene4 ,the augite granules are generally #jb to #jc mm4 in size1 and here and there a prism form gives extinctions of #be4 ,the felspar-lathes which average #aa to #ae mm4 long1 are often rather stout1 showing a few lamell that give extinctions of medium and basic andesine4 ,interstitial glass occurs in fair amount4 ,,species ,c4--,felspar-lathes #b-c mm4 in average length4 ,blackish rocks with sp4 gr4 #bge-bhd4 ,the description of ,species ,b applies here4 ,the plagioclase phenocrysts are for the most part microporphyritic4 ,the size of the augite granules is as above given4 #b4 ,,porphyritic ,,sub-,,genus4--,this group of rocks is mostly confined to the slopes and vicinity of ,mount ,seatura in the western part of the island1 being prevalent in the ,mbua and ,ndama plains1 and occurring also as dyke-rocks in the ,nandi ,gorge leading into the ,ndriti ,basin1 and at and near the coasts of ,wainunu ,bay between the ,tongalevu and ,wainunu rivers4 ,they come near in appearance to the porphyritic forms of the blackish olivine-basalts belonging to genera #ac1 #be1 and #cg of the olivine rocks2 but they differ in the absence of that mineral1 in their lower density1 and in other characters4 ,they are the type to which the term 8porphyritic basaltic andesite0 is most frequently applied in the text when the ophitic structure is not displayed4 ,they are blackish rocks having a specific gravity of #bga to #bha and exhibiting large porphyritic crystals of plagioclase1 but they vary in their minute structure on account of the different size of the felspars of the groundmass4 ,those forming dykes in the ,nandi ,gorge are often more or less propylitic in character4 ,the felspar-lathes1 which have an average length of #b to #c mm41 sometimes show a few lamell giving extinctions of medium andesine 7#ab-bj74 ,the plagioclase phenocrysts of the same andesine are #c to #e mm4 in size4 ,they are eroded and contain abundant magma inclusions4 ,there are a few small phenocrysts of pale brown augite4 ,the augite granules are #jc or #jd mm4 in diameter1 and there is a little dark opaque residual glass4 ,the rocks of the ,mbua and ,ndama plains have a specific gravity of #bha4 ,the plagioclase phenocrysts1 which yield extinctions of basic andesine 7#ba-bg71 are sometimes a centimetre in length4 ,they are traversed by cracks filled with dark altered glass or occupied by brownish films4 ,the felspar-lathes1 which average #aa mm4 in length1 are often stout and lamellar and give extinctions like the phenocrysts4 ,augite phenocrysts are either absent or scanty2 whilst the granules average #jb-jc mm4 in size4 ,there is usually a little interstitial glass4 ,a rock1 almost holocrystalline and #bgd in density1 which was obtained from the ,tongalevu district in ,wainunu ,bay1 approaches the orthophyric type in the character of the ground mass4 ,the felspars are short 7#jf mm47 and stout1 and yield lamellar extinctions of oligoclase 7#e-aj74 ,the plagioclase phenocrysts are of basic andesine4 ,amongst the granules 7#jbe mm47 of pale brown augite occur prismatic forms giving oblique extinctions of #cj4 #ad4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 flu1 gran1 phen1 opac4 ,,characters4--,in the groundmass the felspar-lathes are in flow-arrangement and the augite is granular4 ,the plagioclase phenocrysts are opaque4 ,,description4--,only two rocks are referred to this genus4 ,one which is dark grey with a specific gravity of #bgb is exposed in the gorge of the ,mbutu-mbutu ,river below the falls of ,na ,savu4 ,flow-arrangement is displayed both by the felspar phenocrysts and lathes4 ,the phenocrysts1 #b to #c mm4 in size1 owe their opacity to the abundance of inclusions of brown glass4 ,they are corroded and give extinctions of acid labradorite 7#bf-cb74 ,pyroxene phenocrysts are scanty and small4 ,the groundmass has a characteristic 8pilotaxitic0 appearance1 the densely packed felspar-lathes averaging only #je mm4 in length1 whilst the pyroxene granules are #ja mm4 in size4 ,residual glass scanty4 ,the other rock is from the range behind ,sueni4 ,it shows large porphyritic crystals 7#e or #f mm47 of medium andesine which contain magma-inclusions in abundance4 ,the average length of the felspar-lathe is #jh mm4 and the size of the augite granules is #jb mm4 ,there is but little glass4 ,the rock is somewhat altered4 #af4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 flu1 gran1 non-phen1 parv4 ,,characters4--,in the groundmass the felspar-lathes are in flow-arrangement and the augite is granular4 ,plagioclase phenocrysts are absent1 or if present very scanty and not usually over #a mm4 in size4 ,when present the augite phenocrysts are under #b mm4 ,,description4--,this is a very extensive genus1 admitting considerable variation and including most of the aphanitic augite-andesites1 where the felspar-lathes are as a rule very small 7under #a mm4 in length71 as well as some of the doleritic types where they are very large 7#b to #d mm4 long74 ,in assigning a rock a place in this genus some regard must be paid to its macroscopic aspect as well as to the presence or absence of plagioclase phenocrysts4 ,in many cases two or three small phenocrysts may be observed in a slide1 under a millimetre in size2 but they do not give a character to the naked-eye appearance of the rock1 and such rocks cannot be distinguished from others that do not display them4 ,these rocks range in specific gravity from #bee to #bhe4 ,this large range is in the main concerned with different degrees of basicity depending on the character of the plagioclase1 the relative abundance of the augite granules1 c42 but it is also connected with the amount of interstitial glass4 ,the variety of plagioclase ranges between oligoclase and andesine labradorite4 ,the fluidal structure is nearly always well-marked1 and the closely packed felspar-lathes have often the peculiar 8felted0 appearance of many andesites4 ,a little interstitial glass is present in most rocks4 ,many1 perhaps nearly all1 of the rocks belong either to dykes or to larger intrusive masses4 ,all the four species indicated by the length of the felspar-lathes are represented in my collection1 especially the two with smallest felspars4 ,they may again be split up into two sub-species according to the degree of basicity of the rocks4 ,,species ,a4--,felspar-lathes between #jb mm4 and #a mm4 in average length4 7#a7 ,most basic sub-species4444 ,sp4 gr4 #bge-bhe4 ,dark-brown and dark-grey compact aphanitic rocks showing no plagioclase phenocrysts to the eye4 ,when a few of these phenocrysts are present in a slide they are not usually much over #a mm4 in size1 and give extinctions of andesine labradorite 7#bj to #cj74 ,augite phenocrysts are often absent1 and when present are not over #a mm4 in size and are as a rule scanty1 occasionally affording a suspicion of inter-growths with rhombic pyroxene4 ,the felspar-lathes which display marked flow-structure1 vary in average length in different rocks from #je-jh mm4 ,lamellar twinning is rare1 the extinctions being those of oligoclase andesine 7#aj to #bj74 ,the usual extinction1 as measured from the long axis of the lathe1 is #aj to #ae 7medium andesine74 ,the augite granules are small 7#ja-jb mm47 and abundant4 ,there is generally a little interstitial glass with small magnetite4 7#b7 ,least basic sub-species4444 ,sp4 gr4 #bee-bge4 ,dark compact aphanitic rocks especially characteristic of the ,ndrawa district4 ,when plagioclase phenocrysts are present1 they are very scanty and not generally over a millimetre in size1 possessing rectangular clean outlines and showing but few inclusions4 ,they may display carlsbad twinning and zoning1 or albite twinning1 when they give extinctions of oligoclase andesine 7#aj-ae74 ,pyroxene phenocrysts are either absent1 or scanty and small1 being usually of pale yellow augite with occasional indications of intergrowth with rhombic pyroxene4 ,the felspar-lathes as a rule average #jg or #jh mm4 and present a dense fluidal arrangement4 ,they rarely display lamellar twinning and give extinctions measured from the long axis of oligoclase and oligoclase andesine 7#b-h74 ,the pyroxene granules are very small1 averaging #ja mm4 and less4 ,there is also fine magnetite4 ,a little interstitial glass is usually present4 ,when abundant it is not generally smoky but shows clear fibrous devitrification4444 ,one of the specimens1 which is semi-vitreous1 exhibits tube-like steam-pores drawn out to a length of #a-a centimetres4 ,the felspar microliths are only #jb mm4 in length4 ,the copious glass has the character above described4 ,,species ,b4--,felspar-lathes #a-b mm4 in average length4 ,this species may also be sub-divided into two sub-species 7more basic and less basic74 ,since1 however1 all but one of the fifteen rocks belonging to the species are of the more basic kind my remarks will mainly apply to them4 ,they are dark-brown or dark-grey compact aphanitic rocks1 occasionally banded or streaky1 in appearance1 and ranging in specific gravity from #bge to #bhd4 ,they occur in several districts1 but are especially characteristic of the ,ndrawa district4 ,the plagioclase phenocrysts1 if present1 are very scanty and small 7#a or #a mm474 ,they contain inclusions of the magma and give lamellar extinctions of andesine labradorite 7#bj-cj74 ,pyroxene phenocrysts do not generally occur4 ,when present1 they are small and of pale yellow augite yielding large extinctions4 ,occasionally micro-porphyritic augite is well represented4 ,the felspar-lathes1 which exhibit a well-marked flow-arrangement1 are generally #ac to #ae mm4 long4 ,lamellar twinning is uncommon1 the extinctions measured from the long axis indicating basic andesine 7#aj-bj74 ,the augite granules are abundant and small 7#ja-jb mm474 ,occasional prism-forms yield large extinctions4 ,magnetite is abundant1 its grains corresponding in size to the augite granules4 ,there is as a rule a little residual glass1 which shows fibrous devitrification and is not smoky4 ,the banded appearance of some of the rocks arises from the glass collecting in streaks rudely parallel and running in the direction of the 8flow0 of the felspar-lathes4 ,the only specimen in my collection of 8sliced0 rocks belonging to the less basic sub-species is an altered bluish-grey rock 7sp4 gr4 #bg7 from the range between the ,mbuthai-sau valley and the ,wainikoro plains4 ,its long parallel untwinned felspar-lathes give the nearly straight extinctions of oligoclase4 ,fine cracks in the rock are filled with crystalline silica4 ,,species ,c1 felspar-lathes #b-c mm4 long4 ,,species ,d1 felspar-lathes #c-e mm4 long4 ,the rocks of these species in the collection are for the most part dyke-rocks of the more basic kind4 ,they are blackish or dark-brown1 almost doleritic in texture1 and range in specific gravity from #bgg to #bhg4 ,at times they are vesicular or scoriaceous1 as in the specimens from an agglomerate at ,undu ,point and from a flow or dyke at ,vunikondi4 ,the most typical of these rocks are those of some of the dykes of the ,ndriti basin1 which1 however1 display propylitic alteration in a varying degree4 ,they would be described as semi-doleritic basalts without olivine or as non-porphyritic basaltic andesites4 ,plagioclase phenocrysts are typically absent1 or they are scanty and not over #a mm4 in size4 ,augite phenocrysts are usually scanty and small4 ,the felspar-lathes1 which are more or less in flow-arrangement1 are rather stout1 and range in average length in different rocks from #bc to #ce mm4 ,they often show a few twin-lamell which yield extinctions of medium and basic andesine 7#ae-bh74 ,the augite granules are large 7#jc mm47 in the ,ndriti rocks4 ,magnetites1 usually corresponding in size to the augite granules1 are abundant4 ,interstitial glass occurs often in fair quantity and is dark and semi-opaque4 ,at times there can be recognised a later generation of minute felspar microliths between the much larger lathes4 ,they display a plexus rather than a flow-arrangement4 ,whilst the larger parallel lathes of the ,vunikondi rock1 above referred to1 average #bc mm4 long1 the felspar microliths of the interspaces average only #jc mm4 ,the significance of these two crops of felspars in the groundmass is discussed on page #bcg4 ,the only rock of the less basic sub-species in my collection is from a dyke near ,vatua-karoa4 ,it shows secondary calcite and viridite and other evidences of the propylitic change4 ,the felspar-lathes1 which average #c mm4 in length1 give extinctions of oligoclase 7#j-e74 ,the specific gravity is #bgb4 #e4 ,,sub-,,order1 ,,prismatic1 ,,of ,,the ,,augite-,,andesites 7,felspar-lathes in flow-arrangement4 ,aug1 matr1 flu1 prism47 ,this sub-order includes dark-brown or blackish semi-vitreous rocks1 all but one of which belong to the genus below described4 ,since the exception 7which belongs to genus #ag of the synopsis7 differs only in the presence of plagioclase phenocrysts1 its separate description is not needed4 #bj4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 flu1 prism1 non-phen1 parv4 ,,characters4--,in the groundmass the felspar-lathes are in flow-arrangement1 and the augite is prismatic4 ,plagioclase phenocrysts are absent or are very small and scanty1 and pyroxene phenocrysts when present do not exceed #b mm4 in size4 ,,description4--,these dark semi-vitreous rocks occur in agglomerates and as 8necks0 and dykes1 and are at times scoriaceous4 ,they are usually compact and aphanitic1 showing few if any plagioclase phenocrysts and having a semi-conchoidal fracture4 ,the specific gravity varies1 being generally #bf-bfe1 but according to the degree of basicity and amount of glass it may be as low as #be or as high as #bgg4 ,in the less glassy condition1 as in the case of a rock from the ridge east of ,na ,raro1 the felspar-lathes are relatively scanty and the groundmass is mainly formed of augite prisms in flow-arrangement4 ,the lathes are generally small1 less than #a mm41 and rarely over #b mm4 ,their extinctions are those of oligoclase and acid andesine4 ,the pyroxene prisms1 which give the large extinctions of augite1 have a pale muddy-brown hue and are as a rule #jc-jg mm4 long4 ,granular pyroxene1 if present1 is subordinate in amount4 ,the glass1 which is always in good quantity and is sometimes abundant1 displays fibrous devitrification4 ,in a rock from the vicinity of ,narengali a variolitic structure is exhibited in the form of sheaf-like aggregates of fibre-like felspars and skeleton prisms of pyroxene4 #f4 ,,sub-,,order1 ,,ophitic1 ,,of ,,the ,,augite-,,andesites 7,felspar-lathes in flow-arrangement4 ,aug1 matr1 flu1 oph47 #ba4 ,,genus ,,of ,,the ,,augite-,,andesites ,,formula4--,aug1 matr1 flu1 oph1 phen1 vitr4 ,,characters4--,in the groundmass the felspar-lathes are in flow-arrangement and the augite is ophitic or semi-ophitic4 ,glassy plagioclase phenocrysts4 ,,description4--,dark rocks1 sp4 gr4 #bgf-bh1 forming ancient flows and displaying at times a columnar structure as at ,yanutha ,point 7page #abc74 ,the ophitic character is only in part developed1 which may be connected with the flow-arrangement of the felspars4 ,these rocks come near to the blackish ophitic basalts with scanty olivine 7genus #cc of the olivine sub-class74 ,they all belong to the non-porphyritic sub-genus where the plagioclase phenocrysts are less than #c mm4 in size4 ,these phenocrysts1 which often contain abundant magma-inclusions1 give extinctions of andesine labradorite 7#bj-cj74 ,the augite phenocrysts are small and composite in character as often happens with these ophitic rocks4 ,they sometimes invest the smallest felspar phenocrysts1 and occasionally display intergrowths of rhombic pyroxene4 ,the felspar lathes are #a to #ad mm4 in length1 and give extinctions of medium and basic andesine4 ,the augite granules are large 7#jb-jf mm471 and tend to wrap around the lathes4 ,interstitial glass exists in fair amount4 ,,chapter ,,xx ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,,hypersthene-,,augite ,,class ,,ii4 ,,sub-,,class4 ,,hypersthene-,,augite-,,andesites ,,formula4--,plag1 hypersth-aug1 matr4 ,,characters4--,the pyroxene phenocrysts usually are represented by separate crystals of the monoclinic as well as the rhombic type1 and the two forms are often associated in the same crystal4 ,the monoclinic form prevails in the groundmass in most cases4 ,,remarks4--,it is not possible to draw a sharp line between the augite and the hypersthene-augite-andesites2 but where two or three phenocrysts of the rhombic type occur in a slide the rock may be placed in this division4 ,between this variety and that where rhombic pyroxene prevails1 both among the phenocrysts and in the groundmass1 numerous intermediate kinds exist4 ,these rocks mostly occur in agglomerates and form small and large dykes or sills1 but rarely are found in flows4 ,they are distributed over most of the island except in the western portion 7the basaltic districts of ,wainunu1 ,seatura1 and ,solevu71 but reappear again in the ,mbua peninsula in places1 as at ,mount ,koroma4 ,the pale yellow rhombic pyroxene is uniform in its optical behaviour4 ,the prisms are noticeably pleochroic1 being nearly colourless when lying across the long axis of the lower nicol and pale yellow when parallel with it4 ,the intergrowths with monoclinic pyroxene often take the form of lamellar bands1 whilst in some cases a nucleus of the one 7usually rhombic7 is invested by a growth of the other4 #a ,,sub-,,order1 ,,granular1 ,,of ,,the ,,hypersthene-,,augite-,,andesites 7,felspar-lathes not in flow-arrangement47 ,,formula4--,hypersth-aug1 matr1 non-flu1 gran4 #a genus 7,vitr47 #b 7,opac47 ,see ,synopsis1 p4 #bdg4 #c 7,magn47 #d 7,parv47 ,nearly all of the rocks of this sub-order that are represented in my collection belong to the genus 7#a7 with phenocrysts of glassy plagioclase4 ,they vary considerably in appearance and in colour 7black to grey71 and occur under very different conditions1 as in 8necks10 old flows1 large intrusive masses1 dykes1 agglomerates1 c4 ,their specific gravity has rather a wide range according to the degree of basicity4 ,in the heavier rocks where the rhombic pyroxene is scanty1 it is usually #bg to #bh4 ,in the others1 where rhombic pyroxene is more predominant and where the felspar is less basic1 it is #bf to #bg4 ,in the slide small phenocrysts of plagioclase and pyroxene occur in a groundmass of felspar-lathes and pyroxene granules1 whilst there is as a rule a fair amount of residual glass4 ,the plagioclase phenocrysts1 which give extinctions in different rocks of acid and basic andesine and contain abundant magma-inclusions1 are generally one to two mm4 in size4 ,the pyroxene phenocrysts are small1 and may be represented by separate crystals of the monoclinic and rhombic kinds1 or by crystals displaying intergrowths of the two sorts4 ,the pyroxene granules vary much in size and are evidently in great part of augite4 ,in most of the rocks the felspar-lathes are less than #a mm4 in length4 ,in those where the length is #a to #b mm4 they are sometimes stout and display a few lamell1 yielding extinctions corresponding to those of the phenocrysts4 ,a singular dark grey almost holocrystalline doleritic rock 7sp4 gr4 #bhe7 is exposed in the ,thulanga ,ridge 7p4 #baa74 ,it shows no plagioclase phenocrysts1 but those of pyroxene are numerous1 which1 however1 do not exceed #b mm4 in size1 so that the rock would be referred to genus #d of this sub-order4 ,it appears to be a doleritic form of the plutonic rock found at ,nawi in this neighbourhood 7p4 #baa74 ,the pyroxene phenocrysts are mostly of brownish-yellow augite1 but rhombic pyroxene1 either as separate crystals or as intergrowths1 is not uncommon4 ,the plagioclase lathes are long and fairly stout1 giving at times lamellar extinctions of #bj4 ,their average length is #c mm41 and it is to their large size that the doleritic texture is due4 ,the pyroxenes of the groundmass are similarly coarse 7#b mm471 and include both monoclinic and rhombic forms1 the latter infrequent4 ,there is a slight tendency to semi-ophitic behaviour in places2 but generally these pyroxenes are irregular in shape or rudely prismatic4 #b4 ,,sub-,,order1 ,,prismatic1 ,,of ,,the ,,hypersthene-,,augite-,,andesites 7,felspar-lathes not in flow-arrangement47 ,,formula4--,hypersth-aug1 matr1 non-flu1 prism4 #e genus 7,vitr47 #f 7,opac47 ,see ,synopsis4 #g 7,magn47 #h 7,parv47 ,this sub-order includes rocks varying much in appearance1 but all alike in the presence of prismatic pyroxene in the groundmass and in the absence of flow-arrangement of the felspar-lathes4 ,they belong to the two genera1 with glassy and opaque plagioclase phenocrysts4 ,these crystals are not usually over #b mm4 in size and are of medium andesine 7#ae-bj74 ,the pyroxene phenocrysts are small and may be entirely of monoclinic or of rhombic pyroxene1 or the two may be associated either as lamellar intergrowths1 or by displaying an eroded nucleus 7generally rhombic7 around which a regular crystal of monoclinic pyroxene has grown4 ,the felspar-lathes are in some cases less than #a mm4 long1 and in others #a-b mm4 ,the pyroxene prisms of the groundmass average #ja-jd mm4 in length1 and give both straight and oblique extinctions1 the last prevailing4 ,the specific gravity ranges from #bee to #bge according to the degree of basicity and amount of interstitial glass1 which is usually in fair quantity4 #d4 ,,sub-,,order1 ,,granular1 ,,of ,,the ,,hypersthene-,,augite-,,andesites 7,felspar-lathes in flow-arrangement47 #ac4 ,,genus ,,formula4--,hypersth-aug1 matr1 flu1 gran1 phen1 vitr4 ,,characters4--,glassy plagioclase phenocrysts4 ,,description4--,this is a group of rocks that comes near the basaltic andesites represented in genera #a and #ac of the augite sub-class2 and to the more basic kinds the terms of basaltic andesite is equally applicable4 ,these rocks1 however1 differ in the prevalence of rhombic pyroxene1 which occurs as phenocrysts1 but always accompanied by monoclinic pyroxene1 whether as separate crystals or as inter-growths4 ,such rocks are intermediate between those of the augite and rhombic pyroxene classes4 ,they are particularly characteristic of the ,savu-savu peninsula1 but they are also found in other scattered localities4 ,sometimes they appear to form ancient flows1 and at other times intrusive masses and dykes2 but they are rarely scoriaceous4 ,almost all the rocks in my collection referred to this genus belong to the species where the felspar-lathes of the groundmass are #jb-a mm4 long4 ,they are generally blackish or dark-brown1 and the specific gravity ranges usually from #bgb to #bhc4 ,they display in the slide a fair number of plagioclase and pyroxene phenocrysts in a groundmass of felspar-lathes1 pyroxene granules1 and magnetite1 the interstitial glass being scanty or moderate in amount4444 ,the plagioclase phenocrysts are rarely as large as #c mm41 so that most of the rocks belong to the non-porphyritic group of the genus4 ,these phenocrysts1 which are often zoned1 give extinctions of basic andesine 7#ae-be74 ,they contain magma-inclusions1 sometimes in abundance1 which are arranged in zone-lines4444 ,the pyroxene phenocrysts are small1 the two kinds being always represented in the same slide4 ,in some cases separate crystals occur1 and in others the two are associated as intergrowths1 but in most cases separate and compound crystals occur in the same section4 ,not infrequently the phenocryst is an aggregate of lesser crystals of the two pyroxenes4 ,the monoclinic form is a brownish yellow augite with large extinctions and often twinned4 ,the felspar-lathes of the groundmass1 which usually average #je or #jf mm4 in length1 are either narrow and untwinned1 or they may be stouter and display simple and at times lamellar twinning1 giving extinctions of medium andesine4444 ,the granules of pyroxene are generally #ja-jb mm4 in size2 but occasional prism-forms occur which give sometimes the straight extinction of rhombic pyroxene and at other times the large oblique extinctions of the augite type4 #e4 ,,sub-,,order1 ,,prismatic1 ,,of ,,the ,,hypersthene-,,augite-,,andesites 7,felspar-lathes in flow-arrangement7 ,,formula4--,hypersth-aug1 matr1 flu1 prism4 #ag genus 7,vitr47 #ah 7,opac47 ,see ,synopsis4 #ai 7,magn47 #bj 7,parv47 ,the rocks of this sub-order that are represented in my collection admit easily of a general description1 and since the diagnoses of the genera are given in the ,synopsis1 there will be no need to separately describe each genus4 ,almost without exception these rocks form a constituent of agglomerates in various parts of the island2 and they occur in this condition in some of the highest mountains1 as ,mariko1 ,thambeyu1 and ,koro-mbasanga4 ,the exception refers to a low mound-like hill1 apparently a 8volcanic neck10 that rises from the basaltic plains west of ,mbua 7see page #eh74 ,in about half of the specimens the rocks are referred to section #aj1 where the plagioclase phenocrysts are either small and very scanty or are absent altogether4 ,in a fair number these phenocrysts are opaque 7genus #ah72 whilst in a few they are glassy 7genus #ag74 ,the rocks are typically blackish or dark grey1 and often have a pitchstone-like appearance1 the groundmass being frequently semi-vitreous in character4 ,vesicular and scoriaceous rocks occur at times4 ,in all cases the felspar-lathes and pyroxene prisms are more or less in flow-arrangement2 whilst pyroxene granules1 if present1 are subordinate4 ,the felspar-lathes1 which are either simple or once-twinned and give extinctions of acid and medium andesine1 are usually small1 and average in different sections #je-jh mm4 in length4 ,the pyroxene prisms are pale brown and are #jc or #jd mm4 long4 ,most of them give oblique extinctions of over #be2 but in the same slide some give straight extinctions2 the proportion varies in different rocks4 ,the pyroxene phenocrysts in all the specimens are small 7not over #b mm471 and are rhombic and monoclinic4 ,in most sections the two forms are represented by separate crystals and are also associated in the same phenocryst4 ,those of rhombic pyroxene have often dark borders4 ,there is a considerable amount of a pale brown glass in the groundmass1 more or less devitrified4 ,the specific gravity varies considerably1 but is as a rule between #bee and #bge1 the more basic rocks containing augite in preponderance and basic andesine1 whilst the less basic possess a large proportion of rhombic pyroxene and display oligoclase-andesine4 ,sometimes1 as in the case of a rock composing an agglomerate east of ,nanduri1 where the porphyritic plagioclase is opaque and there is some degree of alteration1 the rock looks very like a porphyrite4 ,,third ,,order1 ,,orthophyric1 ,,of ,,the ,,hypersthene-,,augite-,,andesites ,,formula4--,hypersth-aug1 matr1 orth4 ,,characters4--,felspars of the groundmass short and broad4 ,since the material is insufficient for the separate description of each genus1 a general account of the order is alone given4 ,these rocks are often represented in agglomerates or they occur as large blocks1 either lying on the surface or imbedded in tuffs4 ,many of them are somewhat altered4 ,they are for the most part dark grey dull-looking rocks1 with a specific gravity of #bg to #bh1 showing macroscopic plagioclase together with conspicuous pyroxene phenocrysts4 ,the plagioclase phenocrysts are usually small 7#a to #c mm471 and give extinctions of medium andesine 7#ae-bj7 and in some rocks of acid labradorite 7#cj74 ,they are as a rule corroded and are penetrated by numerous fissures1 whilst they contain a considerable amount of altered magma-inclusions with sometimes other alteration products4 ,the pyroxene phenocrysts are from #b to #d mm4 in size4 ,brownish-yellow augite1 giving extinctions of over #cj1 and pale-yellow rhombic pyroxene of the type before described occur generally in the same slide1 and are frequently associated as intergrowths in the same crystal4 ,they may have regular outlines or dark eroded borders1 and at times they exhibit abundant dark opaque inclusions4 ,the broad felspars of the groundmass are sometimes rectangular and give lamellar extinctions of medium and acid andesine 7#ab-ag74 ,they vary in length in different rocks from #je to #b mm4 and more4 ,the pyroxene of the groundmass is generally granular and coarse 7#jb-je mm474 ,as indicated by the extinctions of occasional prism-forms it is composed of both augite and rhombic pyroxene1 the former prevailing4 ,the prismatic sub-order is also represented1 and here the pyroxene of the groundmass is in great part prismatic1 the length of the prisms not often exceeding #je mm41 whilst both the monoclinic and rhombic kinds occur4 ,interstitial glass varies in amount1 sometimes absent1 sometimes scanty and viriditic1 at other times abundant and opaque4 ,magnetite abounds in the groundmass much of it often being of secondary origin4 ,,fourth ,,order1 ,,felsitic1 ,,of ,,the ,,hypersthene-,,augite ,,andesites ,,formula4--,hypersth-aug1 matr1 fels4 ,,characters4--,the groundmass presents a rudely granular appearance or a blurred mosaic4 ,this order is capable of subdivision1 as in the other orders of the hypersthene-augite-andesites 7see ,synopsis1 page #bdg72 but since it is only represented by six of my rock-sections1 ,i will confine the description to the general characters4 ,these rocks are dark-grey1 sometimes granitoid in appearance1 with specific gravity #bfe to #bge4 ,they usually show some alteration1 arising from secondary changes within the rock-mass2 and probably the felsitic or semi-mosaic appearance of the scanty groundmass is the result of such a secondary change4 ,such rocks in some respects approach the type of the gabbros4 ,they are frequent on the north coast of ,natewa ,bay in the vicinity of ,waimotu and also occur in the ,valanga ,ridge4 ,they generally present themselves as deeper-seated massive rocks exposed by the stripping off of the superficial deposits4 ,there are as a rule more or less conspicuous phenocrysts1 up to #c mm4 in size1 of plagioclase and pyroxene1 in a relatively scanty micro-felsitic groundmass1 displaying a blurred mosaic1 in which a few stout felspar-lathes can still be recognised1 and composed apparently of felspar and crystalline silica4 ,the 8grain0 of the mosaic may range in different rocks from #jje mm4 to #jb mm4 ,the pyroxene of the groundmass is largely decomposed1 and the scanty residual glass is represented by viriditic materials4 ,the plagioclase phenocrysts1 which give extinctions of medium and basic andesine 7#ae-be71 are often semi-opaque and corroded4 ,they are traversed by numerous cracks and often contain many whitish alteration products1 though the lamellar structure is usually well preserved4 ,the pyroxene phenocrysts are composed of brownish-yellow augite 7ext4 #cj7 and pale rhombic pyroxene of the type described before1 either as separate crystals or associated as intergrowths4 ,the rhombic pyroxene crystals are often sub-rounded with dark borders2 and as a rule the pyroxene phenocrysts are much fresher than the plagioclase phenocrysts4 ,as far as can be ascertained1 most of the original pyroxene of the groundmass was monoclinic with a little rhombic4 ,,chapter ,,xxi ,,the ,,volcanic ,,rocks ,,of ,,vanua ,,levu 7continued7 ,,acid ,,andesites ,previous observations on the ,hornblende-,andesites of ,fiji ,,these rocks were first described by ,wichmann#aab from specimens obtained by ,kleinschmidt from the mountain of ,mbuke ,levu in ,kandavu4 ,these ,kandavu rocks had a microfelsitic base1 the porphyritic brown hornblende having usually black borders in which a change into epidote was observed4 ,rhombic pyroxene was only noted as an occasional constituent of a rock from ,ono4 ,renard#aac described these rocks from the vicinity of ,ngaloa ,harbour in ,kandavu and remarked that bronzite was of more common occurrence than the monoclinic pyroxene4 ,in the groundmass were numerous felspar and augite microliths1 whilst there was a porphyritic development of plagioclase1 hornblende1 biotite1 and pyroxene4 ,the hornblende phenocrysts played an important part in the rock-composition1 being surrounded by a black zone of magnetite or bordered by a bacillary aggregate of small pyroxene prisms1 parallel and colourless or greenish1 with extinction-angles of #dj4 ,there was often also a development of biotite in the heart of the mineral1 the whole hornblende section being sometimes thus transformed4 ,mr4 ,eakle#aad has more recently described the hornblende-andesites from ,mbuke ,levu in ,kandavu4 ,as the result of his examination of a collection of volcanic rocks made by the ,agassiz expedition in ,viti ,levu1 ,kandavu1 ,mbenga1 ,totoya1 ,malolo1 ,yasawa group1 and in several other small islands1 he inferred that the hornblende-andesites are much more limited in their occurrence in ,fiji than the augite-andesites2 whilst hypersthene-andesite was only represented in the collection from ,vomo-lailai near ,waia in the ,yasawas4 ,the specimens from ,waia had a microfelsitic base with pseudomorphs of hornblende and some augite4 ,mr4 ,e4 ,c4 ,andrews#aae in his account of his collection of volcanic rocks1 made mostly in the ,lau ,group and ,taviuni1 makes no special reference to hornblende-andesites1 the andesites being mainly augitic1 rhombic pyroxene also occurring as a common porphyritic constituent4 ,it may be inferred from the above and from my own observations in ,vanua ,levu below given that hornblende-andesites have a relatively limited distribution in ,fiji4 ,they are not generally distributed as in the case of the augitic and basaltic andesites2 but are confined to certain localities in ,viti ,levu1#aaf ,vanua ,levu1 ,ovalau1 ,kandavu1 ,ono1 ,malolo1 ,yasawa ,islands1 etc4 ,the occurrence of quartz-andesites or dacites in ,fiji4--,in connection with the existence of these rocks in ,vanua ,levu1 it is noteworthy that except in ,mr4 ,eakle's paper there is no reference in any of these writings to the occurrence of quartz-andesites in ,fiji4 ,wichmann expressly states that the rocks he examined were free from quartz1 and that up to his time 7#ahhb7 no quartz-bearing younger eruptive rocks were known from the ,south ,seas4 ,mr4 ,eakle in #ahii described a holo-crystalline andesite with a felsitic aspect from ,malolo and another similar looking rock from ,vatu ,mbulo1 in the same sub-group of the ,fijian ,islands1 showing quartz both in the phenocrysts and in the microcrystalline groundmass1 concerning which he observed that it was perhaps more of a dacite than an andesite4 ,dacites were found by me in #ahhd in the island of ,fauro in the ,solomon group1#aag and it is probable that they are of more frequent occurrence in the ,pacific than has been generally supposed4 ,as shown immediately below1 they are represented in ,vanua ,levu2 and the extent of their distribution in the island depends on the limits we assign to the definition of the term 8dacite40 ,if we restrict the term to a hornblende-andesite carrying porphyritic quartz and displaying a microfelsitic groundmass1 such rocks1 though they form some of the highest peaks in the ,ndrandramea district1 namely ,ngaingai and ,wawa-levu1 would not be very frequent in ,vanua ,levu4 ,if1 however1 a microfelsitic groundmass is alone necessary to constitute a 8dacite10 the great majority of the acid andesites of the island would fall under this designation4#aah ,this has long been a controverted point in petrology4 ,if ,i adopted the last procedure1 my general classification for the andesites would fall into confusion and many rocks without any quartz would be included in the dacites4 ,in the ,synopsis it will be seen that my classification of the andesites is as far as concerns the great groups based on the mineral and not on the structural characters4 ,there are three sub-classes closely allied to each other1 the hypersthene-andesites1 the hornblende-hypersthene-andesites1 and the quartz-hornblende-hypersthene-andesites or dacites1 which cannot be distinguished at their boundaries by their petrological characters or by their different modes of occurrence4 ,these groups of rocks which include all the acid andesites of the island will now be dealt with4 ,,the ,,acid-,,andesites ,,of ,,vanua ,,levu 7,comprising the hypersthene-andesites2 hornblende-hypersthene-andesites2 and quartz-hornblende-hypersthene-andesites or dacites7 ,these rocks compose in mass numerous isolated hills that rise up abruptly in the interior of the central portion of the island4 ,such hills1 or mountains1 as they might be often termed1 usually attain a height of from #gjj to #abjj feet above the surrounding country1 and possess precipitous slopes and frequently perpendicular cliff-faces4 ,in the geological description of the island1 ,i have referred in detail to these mountains1 when speaking of ,na ,raro1 ,vatu ,kaisia1 ,ndrandramea1 ,ngaingai1 etc42 and illustrations of some of them are included in this work4 ,it may1 however1 be here remarked that they are as a rule rudely conical with rounded or peaked summits4 ,the ground-plan is generally elliptical in outline2 and in consequence the profile often varies from different points of view1 so that as in the case of ,na ,raro1 it is that of a sharp conical peak when the mountain is viewed 8end-on10 or of a broad truncated mass when seen from the side4 ,a similar change of form is to be noticed in the illustrations of ,ndrandramea4 ,no traces of crateral cavities came under my notice4 ,the rocks are neither vesicular nor scoriaceous1 and are usually massive2 but exhibit at times a rudely columnar structure4 ,each hill or mountain has its peculiar variety of these rocks4 ,this is well shown in the ,ndrandramea district4 ,thus the rocks of ,ngaingai and of ,wawa-levu in carrying porphyritic quartz differ from those of all the other hills around4 ,those of ,soloa ,levu are distinguished by the orthophyric groundmass and by the absence of hornblende4 ,those of ,mount ,ndrandramea again have no porphyritic quartz1 but little hornblende1 and possess a micro-felsitic groundmass4 ,the rocks of ,na ,raro and ,vatu ,kaisia differ as regards specific gravity1 the 8grain0 of the felsitic groundmass1 the presence of phenocrysts of rhombic pyroxene1 etc4 ,the characters of these rocks from various localities are contrasted in the table given on a later page1 whilst the different sub-classes to which they belong are described in detail below4 ,,sub-,,class ,,hypersthene-,,andesites ,these are dark and light grey rocks1 sometimes granitoid in appearance4 ,they pass on the one hand into the hypersthene-augite-andesites before described and on the other into the hornblende hypersthene-andesites to be subsequently dealt with4 ,from the former they are distinguished by the great predominance of rhombic pyroxene both as phenocrysts and in the groundmass2 whilst from the latter they are separated by the absence of brown hornblende or its pseudomorphs4 ,these rocks are found in the ,ndrandramea1 ,valanga1 and ,vunimbua districts4 ,they may form isolated dome-shaped hills as in that of ,soloa ,levu1 or they may constitute the deeper-seated rocks of the region from which these hills arise1 as in the ,ndrandramea district4 ,in their general mode of occurrence1 however1 they cannot be treated apart from the allied hornblende-hypersthene-andesites and the dacites4 ,this sub-class may be divided like the hypersthene-augite-andesites into four orders according to the character of the groundmass2 and these are enumerated in the ,synopsis4 ,only the orthophyric and felsitic orders are represented in my collection4 ,of the former the most typical rocks are those composing the hill of ,soloa ,levu which is described on page #ajc4 ,these ,soloa ,levu rocks are lightish grey and granitoid in aspect1 with specific gravity of #bed-bfb1 and displaying abundant porphyritic crystals of pyroxene1 #b-c mm4 in size4 ,in the slides they show a large number of plagioclase phenocrysts together with those of pyroxene in a relatively scanty groundmass1 for the most part orthophyric in texture and without residual glass4444 ,the plagioclase phenocrysts1 which are not usually over #b or #c mm4 in size1 are often tabular and show distinct zone-lines4 ,though they are traversed by minute cracks and have frequently a semi-saussuritic appearance arising partly from change-products and partly from the abundance of colourless inclusions1 they yield clear lamellar extinctions of medium and basic andesine 7#ae-be74444 ,the pyroxene phenocrysts1 which are not much altered1 are in most cases long pale-yellow rhombic prisms with rounded ends1 behaving optically as described on page #bhe2 but intergrowths with monoclinic pyroxene may occur and even separate crystals of augite4444 ,the scanty groundmass1 though in the main formed of short and broad felspars1 #ab mm4 long1 of the orthophyric type1 displays in places a rude mosaic1 apparently of quartz and felspar4 ,it also shows abundant small pyroxenes in the form of small prisms 7#je mm4 in length71 giving extinctions nearly always straight but occasionally oblique 7#cj-ce74 ,as examples of the felsitic order of these rocks1 most of which are altered like the propylites1 ,i will first take the case of those deep-seated rocks that are exposed in the river-bed above ,nambuna in the ,ndrandramea district4 ,in the least altered state they are dark grey and mottled1 and have a specific gravity of #bff-bfi4 ,in section they display tabular zoned plagioclase phenocrysts1 usually more or less occupied by alteration products1 but at times giving lamellar extinctions of basic andesine 7#bj-be74 ,the rhombic pyroxene is more or less replaced by chloritoid pseudomorphs2 whilst the 8grain0 of the mosaic is often coarse 7#jc mm471 and much of it is evidently quartz4 ,the more advanced stages of alteration of these rocks are described in the account of the district given on page #ajf4444 ,similar rocks1 showing pyrites1 occur amongst the blocks of ,vunimbua ,river2 but here the rhombic pyroxene is mostly converted into bastite1 and the groundmass is in part trachytic as well as felsitic in texture4 ,the specific gravity is #bg4 7,in the last survey of my collection ,i have found a solitary specimen from an agglomerate in the ,mbua-,lekutu 8divide10 which must be referred to the order with felspar-lathes in flow-arrangement4 ,it is a pale grey rock showing abundant macroscopic pyroxene prisms1 #b mm4 long1 mostly rhombic but showing also intergrowths with monoclinic pyroxene4 ,the felspar-lathes do not average more than #a mm41 and there is a quantity of small prisms of rhombic pyroxene in the groundmass1 which also contains a little residual glass47 ,,sub-,,class ,,hornblende-,,hypersthene-,,andesites ,this is an extensive group which includes the rocks forming several of the hills in the ,ndrandramea district as well as the isolated peaks of ,na ,raro1 ,vatu ,kaisia1 etc4 ,it passes on the one side into the ,hypersthene-,andesites before described and on the other into the ,hornblende-,hypersthene-,quartz-,andesi tes1 the ,dacites of this island4 ,of the four orders established in the ,synopsis 7page #bcf7 according to the general method there adopted1 the first1 where the groundmass exhibits felspar-lathes not in flow-arrangement1 is not represented in my collection4 ,,second ,,order ,,of ,,the ,,hornblende-,,hypersthene-,,andesites 7,felspar-lathes in flow-arrangement7 ,this order is only represented by three rocks1 all of which belong to the prismatic sub-order where the pyroxene of the groundmass is prismatic and not granular4 ,two of these rocks are very similar in appearance and character1 though coming from different localities on the opposite sides of ,savu-savu ,bay1 one from the agglomerate of ,vatu-ndamu in the ,kumbulau peninsula 7page #ia71 the other from an intrusive mass in the vicinity of ,urata 7page #ahd74 ,they are dark grey1 with specific gravity #bf to #bg1 and display macroscopic crystals of hornblende and pyroxene4 ,in the slide they exhibit in addition numerous phenocrysts of plagioclase1 #a to #b mm4 in size1 in a groundmass showing small felspar-lathes 7less than #a mm4 in length7 in partial flow-arrangement and numerous pyroxene prisms 7#je mm4 long7 giving straight extinctions1 together with a little residual glass4444 ,the plagioclase phenocrysts1 which give extinctions of medium and basic andesine1 are often tabular and display zone-lines4 ,they contain abundant pale inclusions arranged zone-wise4444 ,the hornblende phenocrysts are dark brown1 markedly pleochroic1 and give extinctions up to #ab degrees4 ,they have dark resorption borders and are sometimes deeply corroded4 ,they show in various stages the remarkable conversion at the borders into fine pyroxene1 which is described on page #cjf4444 ,the pyroxene phenocrysts are more numerous in the ,urata rock4 ,they are for the most part of the pale yellow feebly pleochroic rhombic type that prevails in the island4 ,a few phenocrysts of pale augite 7ext4 #ce7 may occur in the same slide2 whilst the two pyroxenes may be associated as intergrowths4 ,a crypto-crystalline variety of these rocks1 where the felspar-lathes and rhombic pyroxene prisms of the groundmass are only in part differentiated1 is found on the hills of ,ndreke-ni-wai on the shores of ,natewa ,bay 7page #bja74 ,it is a pale-grey open-textured rock1 displaying numerous small macroscopic crystals of hornblende4 ,,third ,,order ,,of ,,the ,,hornblende-,,hypersthene-,,andesites 7,felspars of the groundmass1 short and broad1 of the orthophyric type7 ,these rocks occur generally as agglomerates and are more particularly characteristic of the district between the ,mariko ,range and the ,salt ,lake4 ,they belong for the most part to the prismatic sub-order of the group and to the section with plagioclase phenocrysts1 and fall naturally into two divisions corresponding to the two genera with glassy and opaque phenocrysts4 ,the last named would be regarded by some as porphyrites4 ,the specific gravity of the specimens ranges from #beb to #bg4 ,the plagioclase phenocrysts1 #a to #b mm4 in size1 give extinctions indicating in some rocks oligoclase-andesine 7#aj-ae7 and in others basic andesine 7#ae-be74 ,their opacity in the porphyrites is sometimes due to multiple macling1 but more usually it arises from the numerous fine cracks filled with decomposition products that traverse them4 ,the phenocrysts of dark brown hornblende are generally abundant and give extinctions of #ae degrees4 ,they as a rule have dark resorption borders in which the process of conversion into fine pyroxene is in active operation4 ,the pyroxene phenocrysts are scanty and in most cases rhombic2 but intergrowths with augite and separate crystals of the last-named may occur4 ,in the altered rocks or porphyrites they are largely replaced by bastite and viridite4 ,the felspars of the groundmass are broad and often rectangular and may give lamellar extinctions of oligoclase-andesine4 ,the pyroxene in the groundmass of the porphyrites is often partly decomposed4 ,it is as a rule prismatic4 ,a little interstitial glass1 altered in the porphyrites1 is generally present4 ,,fourth ,,order ,,of ,,the ,,hornblende-,,hypersthene-,,andesites 7,groundmass felsitic1 displaying a granular mosaic structure7 ,these are light and dark grey rocks showing usually macroscopic pyroxene and hornblende4 ,they vary considerably in appearance from the open-textured rock to that with a granitoid coarsely crystalline aspect4 ,they generally carry brown hornblende phenocrysts1 but frequently these are represented by pseudomorphs2 and they all have a felsitic groundmass4 ,they are only separated by the absence of porphyritic quartz from the dacites of ,vanua ,levu1 which are treated in the next sub-class4 ,they present all stages from the crypto-crystalline to the holo-crystalline condition1 but all show a groundmass which may be scanty in the more coarsely crystalline rocks4 ,these rocks are characteristic of some of the hills of the ,ndrandramea district and of the isolated peaks of ,vatu ,kaisia and ,na ,raro4 ,they include a large proportion of the acid andesites of the island1 and all belong to the prismatic sub-order with prismatic pyroxene in the groundmass1 and to the section with plagioclase phenocrysts4 ,their specific gravity ranges usually from #bee in the more acid and less crystalline types to #bgd in the most crystalline and basic kinds4 ,in the typical slides they display phenocrysts of plagioclase1 pyroxene1 and brown hornblende in a microfelsitic groundmass formed evidently of felspar and quartz together with much prismatic pyroxene4 ,they may be conveniently divided into three species according to the size of the 8grain0 of the groundmass4 ,of the first species1 where the 8grain0 is less than #ja mm41 the rocks of ,mount ,ndrandramea are typical4 ,they have a crypto-crystalline groundmass where the felsitic structure is in process of development and where the pyroxene prisms or microliths are very minute4 ,the plagioclase phenocrysts 7#a mm4 in size7 give extinctions of acid and medium andesine 7#aj-bj71 and are tabular1 zoned1 and contain abundant pale inclusions4 ,the hornblende phenocrysts1 except in the case of the rocks at the foot of the hill1 are represented by pseudomorphs in various stages of dispersion1 so that this character is likely to be overlooked4 ,the pyroxene phenocrysts are in most cases of the pale yellow feebly pleochroic rhombic type1 but they may present intergrowths of both the monoclinic and rhombic forms4 ,these are light grey rocks with a specific gravity increasing as one descends from the summit1 where it is about #be1 to the base where it is #bg1 a change corresponding with increase of the ferro-magnesian minerals and with the more crystalline structure of the groundmass4 ,the second species1 where the 8grain0 of the mosaic is between #ja and #jb mm41 is represented by the ,vatu ,kaisia rock and by that exposed in the opposite side of the gorge4 ,they are granitoid in appearance and have a specific gravity of #bfh to #bga4 ,large porphyritic crystals of pyroxene and hornblende1 the last sometimes #g mm4 in length1 occur in a dark grey base4 ,in the slide these phenocrysts together with those of plagioclase are displayed in a somewhat scanty holo-crystalline groundmass1 where the 8grain0 of the mosaic averages #jab mm4 ,the plagioclase phenocrysts are zoned1 and give in different crystals extinctions in some cases of oligoclase-andesine 7#aj-ab7 and in others of andesine-labradorite 7#be-cj74 ,the hornblende phenocrysts in their pseudomorphism illustrate the various stages of the process of conversion into fine granular and prismatic pyroxene4 ,the least altered crystals have dark resorption borders and are at times deeply corroded4 ,the pyroxene phenocrysts are for the most part rhombic2 but intergrowths with the monoclinic form occur4 ,the pyroxene of the groundmass consists for the most part of small rhombic prisms averaging #je mm4 in length4 ,the third species1 where the groundmass may be described as a coarse mosaic with a 8grain0 between #jb and #jc mm41 is represented by the rocks of the peak of ,na ,raro and of ,mount ,thokasinga in the ,ndrandramea district4 ,the ,na ,raro rocks are light grey with a specific gravity in the unweathered state of about #bf1 and display macroscopic crystals of glassy plagioclase and hornblende4 ,in the slide they exhibit tabular phenocrysts of the plagioclase1 together with dark pseudomorphs after hornblende1 in a coarsely felsitic groundmass 7grain #jbb mm47 where a little very fine prismatic pyroxene1 apparently rhombic1 occurs4 ,there is also a little altered interstitial glass4 ,the plagioclase phenocrysts are zoned and give extinctions of #ae to #be 7acid and basic andesine71 whilst they often show magma inclusions4 ,an interesting feature of these rocks is concerned with the rarity or absence of phenocrysts of pyroxene4 ,they are to be seen1 however1 in the process of being built up within the substance of the hornblende pseudomorphs1 which consist entirely of minute prisms and granules of pyroxene and of fine magnetite4 ,the process seems to consist in the formation of parallel layers of rhombic and monoclinic pyroxene4 ,the ,thoka-singa rocks are more basic 7spec4 grav4 #bgb to #bgd71 and in the scanty holo-crystalline groundmass approach the plutonic type4 ,they are dark grey granitoid rocks displaying abundant macroscopic pyroxene crystals #b to #c mm4 long4 ,the original hornblende phenocrysts are only represented by traces of pseudomorphs of fine pyroxene and magnetite1 the process of dispersion1 described on page #cjg1 being almost completed4 ,the pyroxene phenocrysts are mostly rhombic2 but intergrowths with the monoclinic form occur4 ,the 8grain0 of the mosaic of the groundmass is coarse 7#jbc mm471 and there is a fair amount of prismatic with a little granular pyroxene1 the prisms1 #jd mm4 long1 giving usually straight extinctions1 whilst the granules are apparently monoclinic4 ,,sub-,,class ,,quartz-,,hornblende-,,hypersthene-,,an desites ,,or ,,dacites ,these rocks are infrequent4 ,they compose in mass the adjacent mountains of ,ngaingai and ,wawa ,levu in the ,ndrandramea district1 and appear also on the lower slopes of the neighbouring mountain of ,navuningumu4 ,they differ chiefly from the hornblende-hypersthene-andesites in the presence of porphyritic quartz1 which1 however1 is not as a rule abundant4 ,in their general origin and affinities and in their mode of occurrence they cannot be separated from the two sub-classes of hypersthene-andesites and hornblende-hypersthene-andesites before described4 ,they all belong to the felsitic order of the sub-class1 and all are referred to the sub-order with prismatic pyroxene and to the section with plagioclase phenocrysts4 ,they are light grey rocks1 with a specific gravity of #beg to #bfa1 showing usually dark pseudomorphs after hornblende and a little porphyritic quartz4 ,in the slide they display these pseudomorphs and quartz crystals1 associated with abundant plagioclase phenocrysts1 in a felsitic groundmass1 evidently a mixture of felspar and quartz1 with fine pyroxene1 mostly prismatic and rhombic4 ,pyroxene phenocrysts are absent or rare2 but they may be seen in process of formation in the substance of the hornblende-pseudomorphs4 ,it is only at times1 as in the instance of the ,navuningumu rock1 that the brown hornblende phenocrysts are in part unchanged and that complete pyroxene phenocrysts occur4 ,in such cases the last may be entirely rhombic1 or may exhibit at times intergrowths with the monoclinic form4 ,the plagioclase phenocrysts1 #b mm4 in size1 are often tabular and zoned and give two sets of extinctions1 indicating acid and basic andesine4 ,their abundant inclusions are arranged in zones4 ,the quartz-crystals1 #a to #b mm4 in size1 present hexagonal sections with rounded angles4 ,they are sometimes traversed by cracks occupied by iron oxide films4 ,the pseudomorphs after hornblende1 which consist of fine pyroxene mixed with magnetite1 exhibit often the building up in their interior of pyroxene phenocrysts1 apparently rhombic1 by long parallel rows of stout prisms4 ,in other cases the pseudomorphs display the different stages of dispersion4 ,the fine pyroxene of the groundmass consists mostly of rhombic prisms 7#jb-jf mm4 long7 with some granules4 ,the 8grain0 of the groundmass is usually between #ja and #jb mm4 ,there is little or no residual glass4 ,the rocks of ,wawa ,levu and ,ngaingai are closely similar1 but they differ in the size of the prismatic pyroxene of the groundmass1 which is coarser in the first-named mountain 7#jee mm4 long7 than it is in the second 7#jbe mm4 long74 ,in both the 8grain0 of the mosaic is about the same 7#jad mm474 ,,tabular ,,comparison ,,of ,,the ,,acid ,,andesites ,,of ,,vanua ,,levu4 ,,note4--,the figures in the columns headed 8,felsitic0 and 8,rhombic0 refer to the size in millimetres of the felsitic 8grain0 and the larger pyroxene prisms4 ,column headings3 ,p3 ,plagioclase4 ,q3 ,quartz4 ,h3 ,hornblende or its pseudomorph4 ,r3 ,rhombic ,pyroxene4 ,m3 ,monoclinic ,pyroxene4 ,o3 ,orthophyric4 ,rh3 ,rhombic4 ,mo3 ,monoclinic4 ---------------------------------------- ------------------------ ,phenocrysts4 ,groundmass4 ---------------------------------------- --- ,locality4 ,sp4 ,structure4 ,pyroxene4 ,gr4,p,q ,h ,r ,m ------------------------ ,felsitic4 ,o ,rh ,mo ---------------------------------------- ----------------- ,ngaingai1 summit #beg #jad #jc pseudom4 ,ngaingai1 lower part #beg #jac #jb pseudom4 ,wawa-levu1 #a1ejj feet #bfa #jae #je pseudom4 ,wawa-levu1 #a1ejj feet #bfa #jad #jf pseudom4 ,wawa-levu1 west side #beg #jbb #jd of base pseudom4 but not on in great mountain part ,ndrandramea1 summit #bdd #jjg #ja only scanty hemi- traces crystalline of pseudom4 ,ndrandramea1 #a1fjj feet #beh #jjh #ja only scanty hemi- traces crystalline of pseudom4 ,ndrandramea1 #a1bjj feet #bfh 8 8 #jjh #ja hemi- crystalline ,ndrandramea1 saddle at #bga 8 #jji #ja base ,kalakala1 #bfa #jb #ja near base pseudom4 in part ,navuningumu#bfe #jb #jc 8 near base in part scanty pseudom4 #bdh #jah 8 ,thokasinga #bgd #jbd #jc pseudom4 ,thokasinga #bgb #jbc #jd ,na ,raro1 #beh #jb #ja upper part pseudom4 scanty ,na ,raro #beh #jbb #ja pseudom4 scanty ,vatu ,kaisia #bga #jac #je in part pseudom4 ,vatu ,kaisia1#bfh #ja #je opposite to in part pseudom4 ,soloa-levu1 #bed #jf upper part ,soloa-levu1 #beg #je upper part ,soloa-levu1 #bfb #jf near base scanty ,soloa-levu1 #bfa #jf near base scanty ---------------------------------------- ----------------- ,note on the ,rhombic ,pyroxene of the three foregoing sub-classes of the ,acid ,andesites4--,the term 8hypersthene0 has been here used as a convenient expression equivalent to 8rhombic pyroxene40 ,the mineral is always a little pleochroic and is never colourless1 and it is only in very rare cases that the term 8enstatite0 could be used4 ,as a matter of fact there is practically only one form of rhombic pyroxene represented in my collections whether in acid or basic andesites or in hemi-crystalline and plutonic rocks4 ,in the acid andesites it occurs not only as phenocrysts but also as minute prisms forming a constituent of the groundmass4 ,this mineral1 when composing the phenocrysts1 presents itself usually as single untwinned prisms which exhibit the typical octagonal cross-sections with much reduced prism-faces4 ,the prismatic sections give straight extinctions2 whilst with the cross-sections we obtain straight extinctions parallel with the pinakoid faces4 ,the colour in transmitted light is pale brownish yellow4 ,the pleochroism1 though usually feeble1 is quite distinct1 the colour being pale yellow when the prism lies parallel with the long axis of the lower nicol1 and almost white when it lies across4 ,not infrequently these phenocrysts behave abnormally and give small oblique extinctions4 ,this is often the case when monoclinic pyroxene occurs in the same section4 ,the association of the two pyroxenes in one crystal can in some cases be clearly recognised4 ,at one time a plate of pyroxene exhibits itself as a coarse aggregate of the two pyroxenes4 ,at other times the two occur as parallel intergrowths1 as in the accompanying figure4 ,but it is rarely that such intergrowths are so typically displayed1 the reason of which has been supplied by ,zirkel in his ,lehrbuch der ,petrographie2 #bnd edit43 ,i4 #bga4 ,note on the 8magmatic paramorphism0#aai of the hornblende phenocrysts4--,reference has before been made in the general description of these rocks to the dark alteration margins of the hornblende phenocrysts4 ,the dark borders display the 8bacillary0 structure noticed by ,renard in the case of some hornblende andesites from ,kandavu in the same group of islands1#abj being composed of minute granules and parallel prisms of pyroxene and also of magnetite grains4 ,with the ,kandavu rocks ,renard observed that the tiny pyroxenes were colourless or greenish and had an extinction angle of #dj4 ,in the ,vanua ,levu rocks1 however1 there is a mixture in these dark margins of both monoclinic and rhombic pyroxene2 and the process may be observed in all stages as it advances into the interior of the crystal1 until a dark pseudomorph or paramorph of pyroxene and magnetite results4 ,when the magnetite prevails1 the pseudomorph may ultimately form a black patch in which the process is obscured4 ,but when1 as is generally the case1 the pyroxenes are more frequent1 it occurs as a dark grey mass4 ,finally follows the dispersion of the pseudomorph1 which first becomes a loosely arranged aggregate of the two pyroxenes and magnetite1 and then breaks down1 and at length is only represented by small pale patches of its original constituents4 ,these patches are easily recognisable1 and in not a few rock-sections offer the only indication of the previously existing hornblende phenocryst4 ,there can be little doubt that this is the source of much at least of the often abundant pyroxenes of the groundmass1 which are usually most frequent in the vicinity of the patches4 ,in the earliest stage when the dark border alone exists1 it is not easy to distinguish the one pyroxene from the other1 the granules and prisms being colourless and very minute1 less than #ja in size4 ,but in a far advanced stage of the paramorphism the granules and prisms become sometimes much larger1 the first attaining a breadth of #jd and #je mm4 and the last a length of #ae mm4 ,finally the interior of the paramorph is seen to be more or less completely composed of very pale brown augite and pale yellow rhombic pyroxene in coarse grains and prisms1 the first distinguished by its oblique extinction of #cj to #ce1 the last recognised by its straight extinction and feeble though distinct pleochroism4 ,although as a rule the paramorph becomes dispersed and its pyroxene constituents are added to the groundmass1 it sometimes exhibits a change of another character4 ,in this case the outer portion is alone dispersed1 whilst the growth of a single large crystal of pyroxene proceeds within the mass4 ,in a later stage1 when the dispersion of the outer part is complete1 we have a fresh-looking pyroxene phenocryst with unformed edges1 on the borders of which little granules and prisms of pyroxene may be seen arranging themselves1 as if the crystal-building was still in progress1 or rather as if it had been interrupted and left unfinished by the too rapid dispersion of the outer portions of the paramorph4 ,it will be gathered from the above that the source of the pyroxene of the groundmass is to be found in the magmatic paramorphism of the porphyritic hornblende4 ,the hornblende is dark-brown1 markedly pleochroic1 and extinctions up to #ae are given in prismatic sections4 ,it is well known that the conversion of a hornblende crystal into an aggregate of pyroxene prisms and magnetite was long since experimentally effected by ,doelter and ,hussak by immersing the hornblende in molten basalt1 andesite1 c4#aba ,i would imagine that the transformation of the hornblende and the dispersion of the paramorph occurred under two conditions2 in the first case whilst the 8flow0 was still in motion when the resulting pyroxene would be mixed up in the magma2 in the second case after movement had ceased1 but before consolidation of the groundmass1 when a paramorph or pseudomorph would be formed4 ,,oligoclase-,,trachytes ,the term 8trachyte0 is here applied in a general sense to a group of light-grey intrusive acid rocks1 having a specific gravity when compact of #bd to #bde and showing phenocrysts of glassy felspar1 but not of quartz4 ,these rocks1 which are especially characteristic of the districts around ,tawaki and ,mount ,thuku and of the ,wainikoro sea-border1 are often open-textured and sometimes a little vesicular1 whilst several of them exhibit some degree of alteration in the groundmass4 ,in all cases they appear to be intrusions rather than surface-flows2 and at times they display a columnar structure4#abb ,the difference between the oligoclase-trachytes in various localities appears to be mainly concerned with the varying degrees of crystallisation4 ,there are two principal varieties4 ,in the most crystalline type there are small phenocrysts of glassy felspar and a few of pale augite1 the angle of extinction of the last being over #cj degrees4 ,the felspar phenocrysts1 which contain but few inclusions and have sharp rectilinear outlines1 in most cases show zoning and give lamellar extinction of #e to #ab indicating oligoclase2 but some of them have the tabular untwinned or simple twinned form of sanidine4 ,the groundmass is in the main composed of minute felspar-lathes1 less than #a mm4 in length1 arranged in a dense plexus1 and giving nearly straight extinctions4 ,but it also contains a number of scattered larger felspar-lathes averaging #b mm4 in length and giving extinctions of #e when simple1 and of #h to #aj when lamellar4 ,there is also some small prismatic augite in the groundmass but often decomposing4 ,the original interstitial glass is represented by numerous reddish-brown patches of devitrified glass4 ,in the second type of these trachytes1 the rock is more open in texture and is at times vesicular1 the specific gravity being usually less than #bd4 ,the general characters are much the same1 but sanidine is better represented among the phenocrysts1 and the groundmass is more blurred2 but when the felspar-lathes are distinct they give an extinction either nearly straight or from #d to #h1 according as they are simple or display lamell4 ,the augite of the groundmass is scanty and more or less decomposed2 whilst the interstitial glass when unaltered is in fair quantity and nearly isotropic4 ,the alteration observed in several of these oligoclase-trachytes is restricted chiefly to the interstitial glass in which secondary quartz and at times calcite and viridite are developed4 ,scarcely any of them are quite free from these changes4#abc ,the pitchstone or vitreous form of these trachytes is displayed in the blocks of an agglomerate-tuff between ,tawaki and ,mount ,thuku4 ,it has a specific gravity of #bcf1 is dark-brown1 and has a conchoidal fracture4 ,phenocrysts of felspar1 mostly oligoclase1 with extinction-angles of #e to #aa1 and often penetrated by the magma1 are inclosed in a semi-isotropic groundmass showing incipient development of felspar and other darker microliths4 ,there are also a few small phenocrysts of pale augite4 ,,quartz ,,porphyries ,,and ,,rhyolitic ,,rocks ,wichmann when he wrote in #ahhb that no quartz-bearing younger eruptive rocks had hitherto been observed either in ,fiji or in the ,south ,sea ,islands generally1 had apparently overlooked ,dana's observations in the ,fijian group4 ,the ,american geologist#abd refers to a rock found on the north-east shores of ,vanua ,levu which exhibited in a greenish base thickly disseminated crystals of quartz 7bipyramidal dodecahedrons1 #a_/h of an inch in diameter7 and glassy felspar1 together with a few sphene crystals4 ,quartz porphyries1 akin to the rhyolites1 are especially characteristic of the north-east part of the island1 to which in fact they are entirely confined4 ,they perhaps are best represented in the vicinity of ,mount ,thuku and in the neighbourhood of the mouth of the ,wainikoro ,river4 ,none of my specimens have the fresh appearance of the ,lipari rhyolites and all are more or less altered4 ,their specific gravity does not exceed #bd1 and they are for the most part intrusive in character4 ,a rock frequently exposed between ,tawaki and ,mount ,thuku#abe contains abundant phenocrysts of glassy felspar 7oligoclase and sanidine7 and quartz in a greenish opaque groundmass having a blurred microfelsitic structure4 ,there appears to have been a secondary devitrification of the groundmass since consolidation4 ,the porphyritic quartz crystals are rounded and about #b mm4 in diameter4 ,another rock displayed in the coast-cliffs on the north side of ,natewa ,bay1 a mile east of ,mount ,thuku1 has a somewhat banded appearance4 ,it shows crystals of quartz1 more or less rounded and #c to #d mm4 in diameter1 together with phenocrysts of glassy felspar 7oligoclase with lamellar extinction of #e and sanidine74 ,the groundmass displays traces of spherulites and is in places semi-isotropic2 but for the most part it is microfelsitic4 ,the type of rock found in the ,wainikoro district and in the adjacent sea-border1 where it may be observed forming dykes in the pumice-tuffs1 is light-grey and loose-textured with a specific gravity of #ba4 ,it exhibits small phenocrysts of quartz and of glassy felspar 7oligoclase #e to #ab1 and sanidine71 with1 in one locality only1 a scanty amount of dark green hornblende yielding extinctions up to #bj4 ,the quartz crystals1 which are #a to #b mm4 in size1 are sometimes bipyramidal2 but are often rounded and have fused-like outer surfaces4 ,the groundmass is semi-isotropic with a blurred aspect1 and shows traces of spherulites and numerous crystallites1 with occasional felspar-lathes giving a nearly straight extinction4 ,an extensively altered quartz porphyry of a different type is associated with other altered rocks at the base of ,mount ,nailotha4 ,it has a specific gravity of #bed1 and displays large opaque crystals of plagioclase1 #b to #e mm4 in size with small quartz crystals #a to #b mm4 across1 in a grey compact matrix4 ,the first-named shows the felspar to be mostly replaced by alteration products2 but occasionally a lamellar extinction of #f or #g can be observed4 ,the quartz crystals are rounded and penetrated by the magma1 and contain numerous strings of fluid-cavities4 ,the groundmass was originally spherulitic2 but this structure is more or less disguised by the development of a mosaic of chalcedonic quartz4 ,it shows some micro-porphyritic patches of viridite and calcite4 ,a singular altered white rhyolitic rock is exposed on the north coast of ,natewa ,bay between ,natasa and ,sangani1 where it is associated with altered tuffs4 ,it is compact with a conchoidal fracture and has a specific gravity of #bdh4 ,the hand-specimen has a banded appearance4 ,under the microscope it appears as a rhyolitic glass for the most part devitrified and rendered opaque by the formation of secondary silica4 ,much of it presents a microfelsitic structure1 the bands appearing as semi-opaque streaks4 ,glassy forms of the quartz porphyries or intrusive rhyolitic rocks are extensively represented in the pumice tuffs of the ,undu ,promontory and of the coasts between the ,langa-langa river and ,lambasa4 ,these tuffs will be found described on page #ccf4 ,fragments of a grey rhyolitic glass looking like perlite are inclosed in the pumice-tuffs near the mouth of the ,wainikoro ,river4 ,under the microscope it is displayed as a colourless glass inclosing phenocrysts of sanidine1 oligoclase 7ext4 #d71 and quartz1 the last with rounded outlines and a fused-like outer surface4 ,the glass shows in places perlitic cracks2 but it is mainly characterised by a vacuolar structure1 the minute cavities being lengthened out in the direction of the flow and displaying eddy-currents around the phenocrysts4 ,the elongated steam-cavities sometimes contain water1 but are usually more or less filled with granular materials4 ,,chapter ,,xxii ,basic ,glasses and ,volcanic ,agglomerates ,,basic ,,pitchstone ,,and ,,basic ,,glass ,,it is not possible to draw a sharp distinction between the pitchstone and the purely vitreous condition of these glasses4 ,the following remarks will therefore apply to both4 ,regarded as components of the pitchstone-tuffs and palagonite-tuffs these rocks have a very extensive distribution in the island2 but in the massive state they are hardly ever to be found1 whilst in the form of agglomerates they are only frequent in certain localities1 as in the cliffs of the ,korotini ,bluff1 in the vicinity of ,mbale-mbale1 on the slopes of ,soloa ,levu1 and in the dividing ridge between the ,mbua and ,lekutu plains4 ,on rare occasions they are to be found in a rubbly condition1 as in the upper part of a basaltic flow described on p4 #ib1 or they may form veins in a more crystalline basaltic rock as at ,vatulele ,bay4 ,their specific gravity ranges from #bfa to #bgg1 and they fuse readily before the blow-pipe1 the melting beginning in the ordinary flame4 ,since they are not dissolved under any condition in ,h,cl1 they would be referred to the old hyalomelane group of basic glasses4 ,one of the most interesting of these rocks occurs on the slopes of ,soloa ,levu4 ,as displayed on the south-west slope1 it presents itself as a brownish-black rock with a specific gravity of #bfa and exhibiting large porphyritic crystals 7#f to #h mm47 of plagioclase4 ,it is generally compact1 but it is in places a little vesicular1 the minute cavities being often filled with a zeolite4 ,the mode of occurrence of this pitchstone-porphyry is described on p4 #ajd4 ,in the slide the plagioclase phenocrysts give lamellar extinctions 7#ba-bg7 of andesine labradorite1 and have regular outlines1 with but few inclusions of the glassy magma4 ,there are also a few small phenocrysts of augite with dark rounded borders and showing in some cases lamellar twinning4 ,the groundmass is a brown rather turbid glass in which dark points of devitrification occur4 ,it is traversed by cracks that also penetrate the felspar phenocrysts4 ,these cracks are filled with a feebly refractive material like palagonite2 and there are traces of the early stage of the palagonitic change in one or two places4 ,this is of importance1 because on the north-west side of the hill occurs the same rock1 in which the basic glass has been converted into a reddish-brown almost opaque palagonite2 but in this case the porphyritic crystals of plagioclase are more affected by the magma1 being rounded and extensively penetrated schiller-fashion by this material2 whilst the augite phenocrysts are somewhat similarly affected4 ,the altered glass is also vacuolar1 the cavities being filled with a zeolite4 ,there is an indication of some degree of crushing in the fracture of some of the felspar phenocrysts in situ4 ,there appears to be a connection1 as shown on p4 #cdb1 between the crushing of a basic glass and the formation of palagonite4 ,it is noteworthy that with this change the specific gravity drops from #bfa in the comparatively fresh rock to #bad in the palagonitised hydrated condition4 ,as another example of these basic pitchstones ,i will take that forming an agglomerate near ,mbale-mbale4 ,it has a specific gravity of #bgg and displays phenocrysts of plagioclase1 olivine1 and augite4 ,the first-named1 which give the lamellar extinction of acid labradorite1 7#bb-bh71 are fresh-looking and only affected to a small extent by the magma4 ,those of olivine and augite are in much the same condition4 ,the glass of the groundmass is rather turbid and displays numerous dark patches of incipient crystallisation1 which in some cases prove to be composed of brush-like crystallites around a clear ,h-shaped nucleus1 and in other cases have a more prismatic form4 ,a vitreous rock having some of the characters of a variolite is found near ,narengali 7see page #aej74 ,it1 however1 has the low specific gravity of #bdc and is not readily fusible with the blow-pipe4 ,it displays an imperfect spheroidal structure on a small scale1 being made up of nodules1 the largest having the size of a filbert4 ,in the slide it appears as a grey glass made up of sheaf-like aggregates of fibre-like crystallites1 apparently of felspar1 with minute skeleton prisms of pyroxene in parallel arrangement1 and is traversed by perlitic cracks4 ,,the ,,volcanic ,,agglomerates ,in this place my remarks will be chiefly confined to a summary of some of the leading features of these formations4 ,the agglomerates1 which pass by all gradations through the tuff-agglomerates into the submarine tuffs1 rank amongst the most prevalent and the most conspicuous of the rocks exposed at the surface in this island4 ,their lithological characters vary according to the type of the massive rocks of the district4 ,thus in the ,ndrandramea district the blocks are composed of the prevailing acid andesites4 ,in the ,koro-mbasanga district they are formed of hypersthene-augite-andesites4 ,in the ,korotini and ,va-lili ranges they are composed of olivine basalts and basaltic andesites4 ,the agglomerates derived from basaltic rocks and basic andesites are by far the most frequent1 and it is to them that the following general observations apply4 ,the basic agglomerates and tuff-agglomerates are found almost everywhere and at all elevations up to #b1ejj feet above the sea and over4 ,they compose the inland cliffs and the long lines of precipitous declivities that give character to the valleys and gorges of the mountainous interior4 ,the blocks are often scoriaceous and semi-vitreous1 but the characters of the rocks will be found described on page #caf4 ,they are generally sub-angular and vary in size from a few inches to one or two feet2 and1 though sometimes heaped together in confusion1 they will generally be found in the case of any extensive exposure to be rudely sorted according to size1 or to present a rude horizontal arrangement4 ,the matrix varies much in amount1 being sometimes barely appreciable and at other times so abundant that the deposit may be termed a tuff-agglomerate4 ,typically it has the character of the palagonite-tuffs of mixed composition described on page #cbf1 being made up of fragments of palagonitised vacuolar basic glass1 portions of crystals of plagioclase and augite1 with the debris of the basic semi-vitreous and hemi-crystalline rocks forming the blocks4 ,when it is scanty it contains neither carbonate of lime nor organic remains2 but in the tuff-agglomerates it may be calcareous and may inclose tests of foraminifera and molluscan shells4 ,from the circumstance that the basic agglomerates overlie submarine sedimentary tuffs and clays almost everywhere1 their submarine origin could alone be safely postulated4 ,there are one or two localities that throw especial light on the conditions under which these accumulations occurred4 ,they are dealt with at some length in the general description of each district and only a brief reference can be made to some of their indications here4 ,the testimony supplied by the interesting exposures on the slopes of ,mount ,thambeyu 7page #agh7 goes to show that after the deposition of the foraminiferous tuffs and clays the stage of the agglomerates was ushered in gradually4 ,the tuffs increased in coarseness1 and afterwards they were covered up with an agglomerate formed of blocks at first only one or two inches in size1 but afterwards of larger dimensions4444 ,curious evidence is afforded by the agglomerates of ,mount ,vungalei 7page #bac71 where two beds of palagonite-tuff1 at elevations of #ijj and #a1gjj feet1 mark two pauses in the accumulation of the agglomerates4 ,in each case the pause was introduced by the gradual decrease of the agglomerates which gave place by gradation to the tuffs4 ,in each case also the pause was followed by a sudden renewal of the deposition of agglomerates4 ,with reference to the maximum thickness of these deposits1 it would appear that on the slopes of the ,korotini ,range this amounts to some hundreds of feet1 if we also include the tuff-agglomerates4 ,their origin is to be attributed partly to eruptions and partly to marine erosion4 ,the two agencies although often associated were in their turns predominant in their different phases1 and it is not too much to suppose that the agglomerates without arrangement1 with scanty matrix1 and composed of scoriaceous blocks1 belong more to an eruptive period1 and that those with abundant tufaceous matrix and sorted blocks are mainly the product of marine erosion4 ,in either case the deposition was submarine4 ,but the history of these agglomerates and of their associated foraminiferous tuffs and clays must of necessity be a complicated one1 since they indicate a minimum emergence of #b1ejj feet4 ,their accumulation first began when a number of vents1 in linear arrangement1 were striving to raise their heads above the surface of the sea4 ,it was continued after the waves had ultimately worn the volcanic islets down to below the sea-level1 and the shoals became covered over with submarine deposits4 ,again and again no doubt this struggle between the eruptive agencies and the waves was renewed1 until at length the great emergence began1 and probably from that date the agency of marine erosion was predominant4 ,when on the island of ,stromboli ,i had presented for my observation at least two modes of agglomerate-building under the sea4 ,there was the ordinary work of the marine erosion of the lava-cliffs1 of which the beach represents but a small part of the result2 and there were the dribbling eruptions of the crater1 from which at intervals of only a few minutes masses of semi-molten lava bounded down the steep slopes into the sea4 ,note on the general characters of the rocks of the basic agglomerates4--,in appearance the basic rocks forming the blocks are often very similar4 ,they are usually compact blackish with a semi-vitreous aspect and display some plagioclase phenocrysts4 ,but to enumerate the types to which they belong would be to go over much of the ground traversed in the classification of the basic rocks1 whether olivine basalts1 basaltic andesites1 ordinary augite-andesites1 or hypersthene-augite-andesites4 ,the groundmass as a rule contains much smoky glass1 but the hemi-crystalline portions of it vary considerably in character4 ,whilst fine granular augite prevails1 semi-ophitic coarser augites are not uncommon1 and prismatic pyroxene1 sometimes of the rhombic form1 is represented in the groundmass of the rocks composing the agglomerates of ,mount ,thambeyu and of the ,sokena ,cliffs4 ,in some localities1 as on the south-west slopes of the ,korotini ,range1 rocks of the basic pitchstone kind are predominant4 ,,chapter ,,xxiii ,,calcareous ,,formations1 ,,volcanic ,,muds1 ,,palagonite-,,tuffs ,,the classification that is adopted in my work on the geology of the ,solomon group with respect to the calcareous formations and volcanic muds of those islands is only in part applicable to the calcareous rocks and volcanic deposits of ,vanua ,levu4 ,deposits strictly comparable with those of the ,solomon ,islands here exist1 and have in some places an extensive distribution2 but many others cannot be referred to that classification4 ,in addition to the calcareous oozes and volcanic muds1 such as are now forming off these reef-bound coasts1 the result partly of marine erosion and partly of sub-aerial denudation1 there are many kinds of submarine deposits in ,vanua ,levu that have been largely formed from the materials ejected by volcanic vents4 ,basic glasses1 for instance1 often finely vesicular and usually converted into palagonite1 enter largely into the composition of submarine deposits that frequently form the surface from the sea-borders to the summits of the mountain-ranges2 and it is by the degradation of a land-surface formed of such materials that the volcanic muds comparable to those of the ,solomon ,islands are mainly produced4 ,it is therefore apparent that we have to distinguish here between the deposits of sedimentary and eruptive origin1 a distinction1 however1 which is not always easy to make1 since they are in both cases submarine1 and doubtless were often in process of forming together4 ,the deposits most prevalent in the island are the submarine tuffs partly sedimentary and partly eruptive in their origin and the overlying volcanic agglomerates4 ,the first are usually palagonitic and calcareous and often contain organic remains1 being usually associated with volcanic muds and clays mainly the product of marine erosion4 ,in connection with the employment of the terms 8upraised0 and 8elevated0 in the case of the ,vanua ,levu deposits ,i will take this opportunity to remark that ,i do not thereby commit myself to the view that there has been an actual upheaval of this region4 ,this is a matter1 however1 that will be found discussed in ,chapter ,,xxvii4 ,,the ,,upraised ,,coral ,,limestones ,these reef-limestones are scantily represented in the island1 though one can scarcely doubt that they were once far more extensive1 having been largely stripped off by the denuding agencies4 ,they are mostly found on the south coast between ,naindi ,bay and ,fawn ,harbour1 and rarely extend to heights greater than #bj or #cj feet above the sea1 usually composing the sea cliffs and not occurring as a rule inland4 ,massive corals are often to be seen imbedded in their position of growth1 as described in ,chapter ,,ii42 and as far as the absence of signs of disturbance is concerned1 these ancient reefs might owe their present situation1 either to the withdrawal of the sea or to the upheaval of the land4 ,such reef-limestones exist over much of the ,pacific1 and they belong to the usual type of these rocks4 ,,shelly ,,and ,,foraminiferal ,,limestones ,these rocks are composed partly of reef-debris1 partly of volcanic detritus1 and partly of the tests of foraminifera 7usually bottom forms71 fragments of lamellibranchiate and gasteropod shells1 together with those of pteropods1 and other organic remains4 ,occasionally separate valves of the genera 8,cardium0 and 8,ostraea0 are inclosed in the limestone4 ,these rocks have been evidently formed in rather shallow water4 ,in places they overlie palagonite-tuffs and clays1 also foraminiferal4 ,similar limestones are doubtless forming at the present time off the coast4 ,they are usually hard in texture and greyish or pale yellow in colour4 ,they contain between #be and #de per cent4 of carbonate of lime2 whilst the residue consists of fragments of minerals 7#aj to #ae per cent471 including plagioclase1 monoclinic and rhombic pyroxene1 and occasionally brown hornblende1 with siliceous casts of foraminifera 7#d to #bj per cent471 mostly formed of chalcedonic silica but sometimes black and glauconitic2 the remainder 7#cj to #dj per cent47 being composed of rounded and sub-angular portions of palagonite and semi-vitreous basic rocks1 of which the larger vary from to #a millimetre in diameter4 ,in some cases the carbonate of lime of the inclosed organic remains has been mainly replaced by more or less crystalline silica4 ,in others a recrystallisation of the calcitic material is in progress1 as described on page #aca2 and the matrix presents in places a mosaic of calcite4 ,these rocks have therefore been subject to some degree of alteration1 the causes probably lying within the mass4 ,they are1 however1 far from frequent4 ,they are best represented in the upper valley of the ,sarawanga ,river in the vicinity of ,tembe-ni-ndio1 where they reach to a height of about #bej feet above the sea4 ,the greatest elevation at which ,i found them was in the mountainous interior of the ,waikawa ,promontory1 where they occur at a height of #a1ajj feet above the sea4 ,as samples1 the results of the examination of two rocks from the ,tembe-ni-ndio district are here appended3-- ,a4 ,carbonate of lime #df per cent4 ,fragments of palagonite and of semi-vitreous basic rocks #cj ,residue ,minerals #ab ,secondary silica replacing the carbonate of lime in the organic remains #ab --- #ajj ,it displays to the naked eye fragments of shells including pteropods1 and numerous tests of foraminifera #b or #c millimetres in diameter4 ,in the section it displays in addition coral debris and a considerable quantity of rounded and sub-angular pieces of palagonite and semi-vitreous basic rocks1 usually less than a millimetre across1 with smaller fragments of minerals 7pyroxene and plagioclase71 and much calcitic material in the matrix4 ,b4 ,carbonate of lime #be per cent4 ,debris of palagonite and of basic volcanic rocks #de ,minerals #aj ,siliceous casts of foraminifera #bj --- #ajj ,the organic remains mainly consist of tests of foraminifera1 many of which occur in the residue as colourless siliceous casts4 ,the fragments1 whether of minerals or of volcanic rocks1 are usually less than half a millimetre across4 ,the foraminifera are mostly small and of the 8,globigerina0 type2 but there is a cast of a tube of some boring-mollusc1 and fragments of shells also occur4 ,,pteropod-,,ooze ,,rocks ,these rocks are bluish-grey when not exposed2 but through the hydration accompanying exposure they become much lighter in colour4 ,they are crowded with pteropod shells1 and contain also small gasteropod and lamellibranchiate shells together with tests of foraminifera both microscopic and macroscopic4 ,they yield between #cj and #dj per cent4 of carbonate of lime1 the residue being made up of disintegrated palagonitic debris and fine clayey material derived from the same source1 together with a fair amount of mineral fragments 7#aj per cent47 which include plagioclase1 pyroxene1 and brown hornblende1 and measure in the case of the larger fragments between #a and #d mm4 in diameter4 ,such rocks are somewhat friable and correspond with the pteropod-ooze rocks of the ,solomon ,islands2 but they are not very frequent1 being best represented on the flanks of the basaltic table-land between the ,wainunu and ,yanawai rivers1 as in the vicinity of the ,nandua tea-plantation where they extend up to #ejj feet above the sea4 ,in this particular locality 7see page #cde7 they overlie horizontally-stratified tuffs and clays1 composed of the debris of a basic glass usually vacuolar but now for the most part converted into palagonite1 and showing a few small tests of foraminifera4 ,these deposits are always either surface or incrusting formations4 ,the circumstance of their passing down into characteristic palagonite-formations is repeated in the case of the ,tembe-ni-ndio limestones1 as observed on page #aca2 and there is no doubt that much of their non-calcareous material is derived from the disintegration of palagonite4 ,sample of pteropod-ooze rock from below the ,nandua tea-plantation4 ,carbonate of lime #ch per cent4 ,palagonitic debris and clayey material #ea ,residue ,minerals #h ,casts of foraminifera #c --- #ajj ,fine clayey material makes up the greater part 7#gb per cent47 of the residue4 ,it presents the microscopic characters of material derived from the degradation of palagonite4 ,amongst the mineral fragments1 of which the larger are #b to #c mm4 in size1 occur brown hornblende1 pyroxene1 felspar1 magnetite1 c4 ,the casts of foraminifera are usually glauconitic1 but a few are of crystalline silica4 ,a number of curious little pellets of palagonite1 oblong or oval in form1 occur in the residue4 ,their size is #c to #f mm41 and they apparently represent the minute amygdules of palagonite that occupy the vacuoles in an altered basic glass4 ,,foraminiferous ,,volcanic ,,mud-,,rocks ,these deposits1 which represent the 8volcanic muds0 forming around the coasts of volcanic islands1 are more or less consolidated clay-rocks4 ,they contain in varying numbers the tests of foraminifera with occasionally pteropod-shells4 ,the former are usually minute and of the 8,globigerina0 type2 but in some rocks larger bottom-forms prevail4 ,the original colour of these deposits is bluish-grey1 but as generally displayed they are pale-brown and considerably affected by hydration and are known as 8soapstones0 in the group4 ,the ultimate effect of exposure is the production of a whitish or yellowish soapy rock that has lost all the carbonate of lime and all the organic remains and breaks down easily in the fingers4 ,such a crumbling material1 when examined with a high power1 cannot be distinguished from the products of the final disintegration of palagonite as described on page #cdh4 ,these deposits are frequently displayed in the lower regions up to elevations of #cjj feet above the sea1 incrusting the basaltic plains of ,lekutu1 ,sarawanga1 ,ndreketi1 and ,lambasa1 that occupy such a large area of the north side of the island1 and exhibiting there in the prevailing horizontality of their beds the same indication that is presented by the vertical position of the columns of the under-lying basalt1 namely1 the comparative absence of disturbance during the emergence4 ,at the foot of the mountains these deposits are interstratified with and finally overlaid by coarse palagonite-tuffs1 also containing marine remains2 and these are in their turn covered over by the agglomerates that often enter so largely into the composition of the mountainous backbone of the island4 ,such beds form apparently the lowest of a series which begins with the foraminiferous clay and ends with the agglomerate4 ,but in some places1 as has been noticed in the cases of the pteropod-ooze rock of ,nandua1 and of the shelly and foraminiferous limestone of ,tembe-ni-ndio1 beds composed largely of characteristic palagonite lie beneath4 ,in the elevated interior of the island these volcanic mud-rocks are usually concealed by the tuffs and agglomerates4 ,occasionally1 however1 they are to be seen exposed by landslips high up the flanks of the mountains1 as on the slopes of ,thambeyu #a1jjj feet above the sea4 ,an interesting exposure of them is displayed in the heart of the island in the face of the ,mbenutha cliffs where the elevation is about #a1ajj feet4 ,here they are overlaid by a thick bed of agglomerate2 and tuff-beds largely made up of vacuolar basic glass debris and showing a few foraminifera are interstratified with them2 but they exhibit signs of considerable disturbance 7see page #aji74 ,these deposits contain between #e and #be per cent4 of carbonate of lime1 and as a rule about #ij per cent4 of the residue consists of fine clayey material derived from the final degradation of palagonite and of basic rocks4 ,the mineral fragments 7plagioclase1 augite1 rhombic pyroxene1 and occasionally hornblende7 vary much in amount1 their average proportion being #ac or #ad per cent4 of the mass4 ,their size is usually less than #b mm4 and does not exceed #d mm4 ,casts of foraminifera are nearly always present in the residue and form generally #c or #d per cent4 of the whole deposit4 ,sometimes they are black and glauconitic2 but more frequently they are white and composed of chalcedonic silica4 ,such casts represent on a small scale the results of the same silicifying operation to which the flints and silicified corals that occur so frequently on the surface in some localities owe their origin 7see ,chapter ,,xxv474 ,with regard to the age of these volcanic mud-rocks of ,vanua ,levu1 it is most likely that as in the case of similar deposits in ,viti ,levu1 which were examined by ,mr4 ,h4 ,b4 ,brady1 they are of post-tertiary origin4 ,samples of the ,suva 8soapstone0 containing #e or #f per cent4 of lime and displaying shells of foraminifera1 pteropods1 and other molluscs1 were obtained from different heights up to #ajj feet above the sea4 ,since #hg out of the #ib species of foraminifera represented in the deposits are known to be living now in the ,pacific1 ,mr4 ,brady had no hesitation in assigning the beds to the post-tertiary epoch4#abf ,,samples ,,of ,,the ,,volcanic ,,mud-,,rocks ,a4 ,from districts west of ,ndranimako1 #ajj feet above the sea4 ,carbonate of lime #bj per cent4 ,fine debris of palagonite and semi-vitreous basic rocks #fb ,residue ,minerals #ad ,casts of foraminifera #d --- #ajj ,the organic remains consist mainly of tests of minute foraminifera of the 8,globigerina0 type1 casts of which1 both glauconitic and chalcedonic1 occur in the residue4 ,about #hh per cent4 of the residue consist of fine clayey materials less than #be mm4 in size4 ,the mineral fragments1 which average about #a mm4 in diameter1 are mostly of felspar with a little pyroxene and brown hornblende4 ,b4 ,from the ,mbenutha ,cliffs1 #a1ajj feet above the sea4 ,carbonate of lime #ae per cent4 ,fine material mainly derived from the degradation of palagonite #fj ,residue ,minerals #bc ,casts of foraminifera #b --- #ajj ,this rock is somewhat hard1 so that the proportion of fine clayey material1 which is however large1 cannot be accurately determined4 ,it shows in places dark streaks composed of an abundance of minute and often perfect tabular crystals of zoned plagioclase and prisms of rhombic pyroxene1 the size in neither case exceeding half a millimetre1 both of them being derived from the acid andesites of the neighbourhood4 ,in the slide it displays minute tests of foraminifera of the 8,globigerina0 type in a matrix formed mainly of palagonitic debris1 fragments of minerals and semi-vitreous basic rocks4 ,the larger fragments of the minerals and of the volcanic rocks do not exceed #ae mm42 but most of the material is very fine4 ,the tests of the foraminifera are sometimes filled with the matrix1 but often they are entirely of calcite and exhibit in polarised light a dark cross4 ,c4 ,from between ,natua and ,mbatiri1 about #bij feet above the sea4 ,carbonate of lime #be per cent4 ,fine material derived from the degradation of palagonite and of semi-vitreous basic rocks #fb ,residue ,minerals #b ,casts of foraminifera #aa --- #ajj ,this is a relatively deep-water deposit1 the foraminifera being minute and of the 8,globigerina0 type4 ,about #ij per cent4 of the residue consists of fine clayey material1 with which the calcite is so intimately mixed that each particle is highly refractive and effervesces freely in an acid4 ,the mineral fragments 7pyroxene and felspar7 are very scanty1 the largest being less than #be mm4 ,the white casts of foraminifera1 composed of chalcedonic silica1 form a conspicuous elements in the residue4 ,d4 ,from the vicinity of ,mbatiri1 #ajj feet above the sea4 ,carbonate of lime #d per cent4 ,fine material derived from the degradation of palagonite #ij ,minerals #b ,casts of foraminifera #d --- #ajj ,about #id per cent4 of the residue consists of fine clayey material4 ,the fragments of minerals are very scanty and are all less than #b mm4 in size4 ,the casts of foraminifera are white and of chalcedonic silica4 ,from the fineness of the materials and the small size and pelagic character of the foraminifera1 this deposit may be regarded as formed in relatively deep water4 ,e4 ,from the eastern flank of the ,wainunu table-land1 #bjj feet above the sea4--,this is a shallow-water deposit and contains1 besides small gasteropod shells1 large flat tests of foraminifera #e or #f mm4 in diameter4 ,it possesses #bd per cent4 of carbonate of lime1 #fb per cent4 of palagonitic debris1 c41 and #ad per cent4 of minerals4 ,,altered ,,volcanic ,,mud-,,rocks ,this group includes compact hard foraminiferous usually dark-brown rocks1 which exhibit evidence of alteration in their induration1 in the presence of pyrites1 and in the chalcedonic quartz filling fine cracks in the rock-mass4 ,occasionally special types of alteration occur1 one of which will be referred to in the description of some of the rocks given below4 ,the proportion of carbonate of lime is generally small2 but sometimes it amounts to #aj per cent4 or more4 ,they admit of being examined in thin sections2 and their true nature is at times so much disguised that ,i have taken them at first for aphanitic basic andesites4 ,in the slide they display a few scattered tests of foraminifera of pelagic habit in a matrix composed of the fine debris of palagonite and of basic rocks1 together with fragments of plagioclase and pyroxene4 ,most of the material is very fine1 and the size of the largest mineral fragments does not exceed #b mm4 ,such rocks1 however1 are not very frequent4 ,they may be displayed on the flanks of mountain-ranges buried beneath basic tuffs and agglomerates1 as in the case of ,mount ,mariko 7page #ahg7 and of the mountain-slope behind ,mbale-mbale 7page #aeh72 or they may be found at much lower levels as at ,savarekareka ,bay 7page #aij71 where1 however1 they assume sometimes a peculiar character4 ,though in the last-named locality the alteration is possibly connected with thermal metamorphism1 it is probable that in most instances it is a normal interstitial change occurring in beds of some antiquity which are covered over by a considerable thickness of later deposits4 ,in places1 where these rocks have been subjected to much hydration in the weathering process1 they become red in colour1 as is found on the flanks of ,mount ,mariko4 ,,samples ,,of ,,the ,,altered ,,volcanic ,,mud-,,rocks ,a4 ,from between #djj and #ejj feet above the sea on the south slope of the ,mariko ,range4444 ,the characters and mode of occurrence of this rock are described on page #ahg4 ,b4 ,from an elevation of #a1ajj feet on the south slope of the ,korotini ,range4444 ,the description of the locality will be found on page #afj4 ,this rock is hard and compact and looks like an altered basic rock showing a few minute specks of pyrites4 ,it is composed of fine palagonitic debris1 and small fragments of semi-vitreous basic rocks and of crystals of pyroxene and felspar1 none of the fragments exceeding #b mm4 in diameter4 ,tests of minute foraminifera1 filled with matrix and of the 8,globigerina0 type1 occur very scantily4 ,there is little or no carbonate of lime2 but secondary silica1 both colloid and crystalline1 is present as an alteration product4 ,c4 ,from the vicinity of ,yaroi1 #cj feet above the sea4444 ,the locality is described on page #ahi4 ,this is a dark grey hard compact rock1 containing probably between #aj and #ae per cent4 of carbonate of lime1 and looking like an altered limestone4 ,in the section it displays minute tests of foraminifera of the 8,globigerina0 type in a matrix composed of fine disintegrated palagonitic material1 impregnated with calcite and containing also fragments of minerals 7augite and felspar71 none of which exceed #b mm4 in diameter4 ,there are also a few similar-sized fragments of semi-vitreous basic rocks4 ,some fine cracks in the rock-mass are filled with a quartz mosaic4 ,the tests of the foraminifera remain calcitic2 but their cavities are filled either with the matrix or with calcite or with a colourless fibro-radiate mineral polarising in blackish-blue hues4 ,d4 ,from the south shore of ,savarekareka ,bay4444 ,the locality is described on page #aij4 ,this is a bright green hard compact rock with flinty fracture and not effervescing with an acid4 ,in the slide it shows a few casts of foraminifera of the 8,globigerina0 type in a matrix composed mainly of fine debris 7#ja-jd mm47 of felspar and pyroxene with much greenish opaque amorphous alteration products4 ,the abundance of pyroxene is remarkable4 ,the material of the tests of the foraminifera is altogether replaced by a greenish yellow mineral1 occurring in grains and radiating prisms1 apparently epidote4 ,e4 ,from an elevation of #iej feet on ,mount ,thambeyu4444 ,the locality is described on page #agg4 ,a hard dark grey rock containing #aj or #ae per cent4 of carbonate of lime and showing fine specks of pyrites4 ,in the slide are displayed numerous tests of foraminifera of varying size up to #e mm42 scattered patches of pyrites2 fragments of a semi-vitreous basic rock1 not exceeding #ae mm4 in diameter1 and of plagioclase and pyroxene2 in a matrix of the finest debris of the same materials impregnated with granules of calcite4 ,the tests of the foraminifera are filled either with calcite1 showing a black cross in polarised light1 or with a zeolite1 or with pyrites1 or with the matrix4 ,,submarine ,,basic ,,tuffs ,,of ,,mixed ,,composition ,these tuffs1 which are composed not only of palagonitic materials but also of the fine detritus of usually semi-vitreous basic rocks1 rank first in frequency amongst the volcanic sedimentary deposits of the island4 ,in their character they pass on the one hand into the foraminiferous volcanic mud-rocks or clay rocks and on the other into the tuff-breccias and tuff-agglomerates4 ,we have here a series beginning with the agglomerate and ending with the clay that represents in a general sense the successive stages of the degradation of the same materials4 ,these tuffs occur at all elevations from the sea-border1 where they may form the shore-cliffs1 to the upper slopes and summits of the mountain-ranges1 where they are found at elevations between #b1jjj and #b1ejj feet above the sea4 ,in the interior of the island they are generally to be observed underlying the basic agglomerates4 ,wherever an extensive exposure of the agglomerates exists in the mountainous districts1 these tuffs are as a rule to be found at the base of the cliffs4 ,the precipitous bluff of agglomerate1 that so often gives a character to the mountainous interior1 and the line of cliff of the same formation that runs along the slopes1 represent the work of landslips1 as is shown by the huge masses of agglomerate lying on the ground below4 ,these 8slips0 are not uncommon1 and are due to the undermining influence of the springs that percolate through the tuffs and clays underlying the agglomerates4 ,when the tuffs are well displayed they as a rule show stratification4 ,the bedding may be indicated either by distinct parting-lines or by alternating bands of varying degrees of coarseness4 ,that these deposits1 when occurring in mass in the upland regions1 are often horizontal or but slightly inclined1 is evidenced by the ,nganga-turuturu ,cliffs1 #a1bjj feet above the sea1 which are described in ,chapter ,,viii41 in the line of cliffs behind ,sealevu 7,chapter ,,xi471 and high up the slopes of ,mount ,thambeyu 7,chapter ,,xii47 as high as #a1ejj feet4 ,this is also shown in the circumstance that the line of junction with the overlying agglomerate1 except in rare cases1 as in that of the ,mbenutha ,cliffs1 is generally horizontal4 ,it is1 however1 not uncommon to find the beds exposed on the mountain-flanks dipping away from the axis of the range at a small angle1 as on the slopes behind ,mbale-mbale and in the ,sokena ,cliffs4 ,in the lower regions1 where these deposits are associated with the volcanic mud-rocks on the basaltic plains1 they are but slightly inclined4 ,on the other hand1 as in the ,kumbulau district1 the sea-cliffs for some miles may be composed of tuffs more or less steeply tilted4 ,these tuffs are generally more or less compacted and have a greyish colour2 but as usually exposed in a weathered condition they are often pale brown or yellowish and are more friable4 ,they may be uniform in structure1 or they may display thin seams of a marl-like clay1 or they may contain numerous lapilli of vesicular basic glass extensively palagonitised4 ,not uncommonly they contain larger fragments of basic rocks1 and when these are at all frequent the terms 8agglomerate-tuff0 or 8tuff-agglomerate0 have been employed according to the preponderance of either material4 ,many of these tuffs show no effervescence with an acid2 and this is especially the case with specimens at all weathered4 ,on the other hand there are just as many that contain a little carbonate of lime1 not usually more than #c or #d per cent41 but sometimes amounting to #ab or #ac per cent4 ,it often happens in the case of a series of tuffs1 apparently non-calcareous1 that an occasional thin band of a fine clay-like rock contains a good percentage of lime4 ,it is pointed out below1 however1 that the absence of effervescence does not necessarily imply the absence of foraminiferous tests4 ,tests of foraminifera1 often macroscopic bottom forms1 together with shells of small gasteropods1 are displayed at times2 but they are as a rule in such cases not frequent4 ,i found foraminiferous tuffs at considerable heights in some localities1 as for instance between #b1jjj and #b1ejj feet on the slopes of ,mount ,thambeyu 7page #agh71 at an elevation of #a1hej feet on the south slope of the ,korotini ,range above ,vatu-kawa 7page #aeh71 and between #b1jjj and #b1djj feet on the summit of the range between ,waisali and ,sealevu 7page #aed74 ,in the last-named locality1 where the tuffs are coarse and often of the nature of agglomerate-tuffs1 they are highly fossiliferous2 but such a character is exceptional4 ,the submarine origin of the tuffs can often be demonstrated in the absence of evidence of organic remains1 as by their interstratification with foraminiferous clay rocks1 such as we find at an elevation of #a1jjj to #a1ajj feet on the top of the 8divide0 between the ,ndreketi and ,lambasa basins4 ,a single seam of marl-like rock displaying only a solitary test of a foraminifer in the slide may throw light on the origin of the coarser tuffs with which it is associated4 ,the use of the microscope is essential in the case of some of the harder tuffs1 where there has been a little alteration4 ,here casts of foraminifera may be observed1 although no carbonate of lime is indicated by an acid4 ,in some localities where no organic remains are evident in the tuff1 fine waterworn gravel is to be noticed4 ,these deposits are composed as a rule of sub-angular fragments of semi-vitreous basic or basaltic rocks and of palagonite1 together with fragments of plagioclase and pyroxene1 the interspaces being filled with fine debris of the same materials4 ,the relative proportion1 however1 of the three principal constituents varies considerably1 the palagonite1 for instance1 being sometimes scanty and sometimes abundant4 ,the size of the larger fragments in a tuff of the most common kind is about a millimetre2 but deposits rather finer and rather coarser are also frequent4 ,in the very coarse tuffs and in the breccia-tuffs1 where the larger materials are mostly of palagonite1 the larger fragments may be a centimetre in size and even more1 the interspaces being filled with fine debris of the same character cemented together often by carbonate of lime4 ,the fragments of semi-vitreous basic rocks forming a regular constituent of these tuffs are usually dark and opaque and display a few plagioclase lathes4 ,they correspond with the type of the semi-vitreous basalt or basaltic andesite1 of which the blocks of the overlying agglomerates are as a rule composed and are doubtless derived from the same source4 ,fragments of unaltered basic glass are rarely to be observed in these tuffs4 ,it is as a rule all converted into palagonite4 ,this material presents itself in various stages of secondary alteration1 from the compact greenish or yellowish waxy mass to a white friable pulverulent substance1 which represents the last stage of degradation4 ,these changes will be found described on page #cdh4 ,it can1 however1 be stated here that they are mainly concerned with hydration4 ,in the case of the lapilli of finely vesicular basic glass1 that is1 of basic pumice1 which are inclosed in some of the tuffs1 all stages of the secondary alteration of palagonite are often exhibited1 and the last stage of the change is merely indicated by a white powdery patch containing a few minute siliceous amygdules4 ,the puzzling little white patches so common in basic tuffs merely represent lapilli of basic pumice that have been palagonitised1 and then bleached and disintegrated by hydration4 ,the minerals are more or less abundant and may constitute a third of the whole mass4 ,they include plagioclase1 augite1 rhombic pyroxene1 and magnetite1 olivine being rare and scanty4 ,entire crystals of any size are infrequent4 ,however1 crystals of augite1 #e or #f mm4 in length1 are found in the tuffs at ,naivaka and of the coast cliffs near the ,salt ,lake ,passage4444 ,it may be observed that zeolitic minerals which are frequently developed in the tuffs consisting almost entirely of palagonite are not typical of the tuffs of mixed composition4 ,there is nothing suggestive of recent eruptions in any of these formations4 ,they were formed ages since on the sea-floor at varying depths around volcanic vents4 ,sometimes a cone was able to rear itself above the level of the sea2 but in most cases it rapidly succumbed to breaker-action4 ,three agencies1 concerned with sub-aerial eruptions1 submarine eruptions1 and marine denudation1 have co-operated in the production of these deposits1 but their parts in the process have varied greatly4 ,the last is indicated when the tuff is formed of a variety of basic rocks with but little palagonite4 ,the tuffs containing much palagonite representing an original vacuolar basic glass are regarded as mainly the products of submarine-eruptions4 ,in those cases where lapilli of altered basic pumice occur in the deposit1 sub-aerial eruptions are directly indicated4 ,when an extensive exposure of these tuffs occurs1 as in the case of the ,nganga-turuturu ,cliffs and in that of the section displayed near the hill of ,korolevu 7page #dh71 all three agencies are often illustrated4 ,,samples ,,of ,,the ,,submarine ,,basic ,,tuffs ,,of ,,mixed ,,composition ,a4 ,as examples of the non-fossiliferous tuffs where the palagonite constituents do not predominate1 ,i will take those exposed in beds in the coast cliffs and in the low hills in the vicinity of ,na ,tokalau in the ,kumbulau peninsula 7page #ij74 ,they are grey in colour and have the texture of a sandstone1 being more or less compacted and showing no effervescence with an acid4 ,they are composed of fragments of basic rocks and of minerals1 varying in size from #e to #a mm41 in a scanty matrix made up of fine detritus of the same materials and of palagonitic debris4 ,the fragments of volcanic rocks are rounded and sub-angular1 and formed mainly of a basaltic rock1 with a black opaque groundmass showing some small plagioclase crystals and in places more or less palagonitised4 ,there are also portions of a hemi-crystalline basic rock showing small augite crystals4 ,the minerals entire and in fragments1 which make up quite a third of the mass1 are mostly of plagioclase1 but monoclinic and rhombic pyroxene are also well represented4 ,it is evident that through the alteration of the palagonitic constituents1 which were probably more frequent when the tuffs were deposited1 the structure of the matrix is somewhat disguised4 ,b4 ,a yellowish grey tuff composing the cliffs on the north coast of ,naivaka affords a good example of a tuff where the palagonitic materials predominate4 ,it is somewhat fine-textured and displays a tendency to lamination4 ,the powdered material effervesces slightly with an acid4 ,in the slide it is exhibited as composed mainly of palagonite and of fragments of minerals1 the latter making up about one-third of the whole and ranging in size usually between #b and #e mm4 ,a number of more or less parallel fine cracks1 filled with calcite and traversing also the inclosed crystals of plagioclase1 together with small fragments of basic rocks are displayed in the section4 ,there are a few fragments of semi-vitreous basic rocks1 as just indicated1 but the palagonite is the principal constituent4 ,it shows numerous minute amygdules occupying the original vacuoles of the basic glass2 and in its substance occur irregular patches formed of a colourless semi-isotropic mineral which is either zeolitic or a form of opal4 ,plagioclase and augite compose the mineral fragments1 the former prevailing4 ,although these tuffs are derived from a vent that was probably the last in eruption in this island1 they display considerable alteration which is mainly connected with the secondary changes affecting the palagonite since the deposition of these materials4 ,c4 ,as an example of the banded tuffs composed of coarse and fine materials ,i will take a compact grey rock forming one of the horizontal beds in the natural section exposed near the hill of ,korolevu 7p4 #di74 ,it is also an example of those tuffs which whilst not effervescing with an acid display a few casts of foraminifera in the slide4 ,the alternating bands which are about a centimetre in thickness pass gradually into each other4 ,the bands of finer materials are made up of sub-angular fragments1 #a to #b mm4 in size1 of the dark opaque groundmass of a semi-vitreous basic rock and of a grey hemi-crystalline groundmass of an augite-andesite1 together with palagonite more or less decomposed1 and fragments of plagioclase and augite1 whilst the interspaces are filled with the finer debris4 ,the layers of coarse materials have much the same composition1 the fragments varying usually between #e and #a mm4 in diameter1 with occasional larger pieces of palagonite #b to #e mm4 in size representing original lapilli of a vacuolar basic glass4 ,the tests of the foraminifera1 which occur scantily in the layers of fine material1 are all minute4 ,they are filled with palagonitic material4 ,d4 ,the tuffs prevailing on the higher flanks of the mountainous backbone of the island are well represented by those exposed at an elevation of #a1bjj feet above the sea on the south slope of the ,korotini ,range behind ,mbale-mbale4 ,it is a somewhat coarse-grained rather hard grey rock effervescing feebly with an acid4 ,it is composed of sub-angular or partly rounded fragments1 #a to #d mm4 in size1 of various basic rocks1 and of rather smaller fragments of plagioclase and augite1 the interstices being filled up with fine debris of the same materials1 in which a few minute tests of foraminifera of the 8,globigerina0 type may be observed4 ,the basic rocks of which the fragments are formed comprise the following3 7a7 a grey aphanitic augite-andesite1 with but little interstitial glass1 presenting a parallel arrangement of the minute felspar-lathes which have an average length of #je mm42 7b7 a grey augite-andesite of coarser texture but in other respects similar1 the felspar-lathes being about #a mm4 in length1 whilst there is a little microporphyritic plagioclase2 7c7 a semi-vitreous basaltic rock showing small porphyritic crystals of plagioclase and augite in a groundmass usually black and opaque1 but sometimes smoky and displaying felspar microliths2 7d7 a vacuolar basic glass more or less palagonitised4 ,e4 ,as a specimen of the calcareous tuffs those exposed on the south slope of the ,korotini ,range at an elevation of #a1hej feet may be given4 ,they contain about #aa per cent4 of carbonate of lime and inclose a few tests of foraminifera #a to #b mm4 in diameter4 ,the other constituents are fragments of semi-vitreous basic rocks and of palagonite1 together with fragments of plagioclase and pyroxene crystals and of an amorphous siliceous mineral which behaves optically like chalcedonic silica4 ,when the rock is gently rubbed down1 minute fragments of this white mineral can be picked out4 ,they have a wrinkled surface and an irregular form and are not affected by acids4 ,in polarised light they display a rude mosaic or an imperfect radiate structure4 ,f4 ,as specimens of the fossiliferous agglomerate-tuffs composed mainly of palagonite1 those exposed on the high mountain slopes of the ,korotini ,range at heights of #b1jjj feet may be here cited4 ,they are described on p4 #aed4 ,note4--,the examples of mixed tuffs above given represent only some of the principal types of these deposits4 ,short descriptions of others will be found in the detailed account of the geology of the island4 ,,altered ,,basic ,,tuffs ,,of ,,mixed ,,composition ,these form a group of hard compact rocks1 the fragmental character of which is not always apparent in hand-specimens1 microscopical examination of thin sections being usually required for the determination of their true nature4 ,they are commonly exposed on the southern flanks of the ,korotini ,range at the back of ,vatu-kawa and ,nukumbolo4 ,they are composed of compacted fragments1 varying in different localities from #a to #e or #f mm4 in size1 of a variety of semi-vitreous basic rocks1 the matrix being scanty but often containing zeolites and secondary silica1 whilst occasionally secondary calcite is developed4 ,they contain no organic remains1 and palagonite when present is usually scanty1 whilst viridite and similar materials represent the decomposition of the pyroxene4444 ,a hard breccia-tuff found on the flanks of ,mariko and in one or two other localities contains vesicular fragments1 where the steam-holes are filled with opal or chalcedony1 and the cracks traversing the matrix are also filled with this mineral4 ,the alteration of these tuffs has evidently arisen from a variety of causes4 ,in some cases the change appears to be purely interstitial4 ,in other times it has arisen from contact-metamorphism1 or from hydro-thermal agencies1 as in the case of the altered tuffs near the hot springs at ,nukumbolo 7p4 #afa74 ,,submarine ,,basic ,,pumice ,,tuffs ,these deposits1 which1 however1 are not of frequent occurrence1 are interstratified with volcanic mud-rocks in certain localities1 as at the ,mbenutha ,cliffs 7p4 #aaj71 and in the vicinity of the hill of ,korolevu 7p4 #dg74 ,they indicate periods of volcanic activity during the deposition of the foraminiferous muds1 with which they are associated1 when the fine materials ejected from sub-aerial vents fell into the seas around4 ,such tuffs are more or less compact and usually fine in texture4 ,when the glass fragments are but slightly altered1 the tuff-rock is dark grey2 but when the palagonitic change is well advanced1 it becomes pale and yellowish4 ,they are made up chiefly of small fragments of a bottle-green basic glass1 which are as a rule vacuolar and sometimes fibrillar2 but it never happens that the pumiceous character is as pronounced as in acid pumice2 and in some cases the vacuoles or steam-pores are to be observed only in the minority of the fragments displayed in a slide4 ,the size of the glass fragments is as a rule small1 in some tuffs averaging only #a mm4 and in others #e mm42 but occasionally they may be #a or #b mm4 in diameter4 ,fragments of minerals 7plagioclase and pyroxene7 corresponding in size to the glass fragments are as a rule well represented1 forming a fourth or a third of the mass4 ,a little fine detritus of a semi-vitreous basic rock also occurs4 ,tested in an acid several of the tuffs either do not effervesce or give an indication of a small percentage of carbonate of lime2 whilst others effervesce freely4 ,they usually display a few minute tests of foraminifera of the 8,globigerina0 type1 the cavities of which are filled with fine palagonitic debris4 ,the palagonitic alteration is to be noticed in all cases2 but it varies considerably in its extent4 ,in the dark grey tuffs it affects the margins only of a few of the glass-fragments4 ,in the paler tuffs it has extended more into their substance1 although the alteration is never more than partial4 ,the pale greyish material filling up the interspaces is composed of disintegrated palagonite4 ,the steam-pores or vacuoles are sometimes empty2 and at other times1 especially where the palagonitic change has begun1 they are filled with a granular alteration product4 ,the glass fuses readily2 but is not affected by acids4 ,it is clear and isotropic1 showing however a few scattered microliths4 ,these tuffs correspond with the hyalomelan-tuff from the island of ,munia in this group as described by ,wichmann2 but in that instance no mention is made of inclosed tests of foraminifera4 8,,crush-,,tuffs0 ,,formed ,,of ,,basic ,,glass ,this is a remarkable group of compacted tuff-like rocks which as hand-specimens would be generally regarded as pitchstone-tuffs4 ,their detrital origin is1 however1 often very doubtful4 ,they are composed of fragments of basic glass1 carrying plagioclase phenocrysts1 with the interspaces occupied by palagonite and by the finer debris of the glass and felspar4 ,the larger glass fragments1 which vary in different rocks from #a or #b to #d or #e mm4 in size1 have been crushed in situ1 the broken portions often remaining more or less in position4 ,these fragments are invested by palagonite and have eroded borders1 as shown in the figure on page #cdb4 ,the glass is bottle-green1 non-vacuolar1 fuses readily1 and only at times displays incipient crystallisation4 ,the explanation of the origin of these rocks is attempted in ,chapter ,,xxiv4 ,they contain neither carbonate of lime nor organic remains4 ,the most typical example is present in a bed underlying a pitchstone-agglomerate near ,narengali 7see page #adi74 ,it is not uncommon to find evidence of crushing in the glassy matrix of a pitchstone-agglomerate or of rubbly pitchstone1 as in the ,va ,lili ,ridge 7#adb71 the ,korotini ,bluff 7#aeg71 and ,mount ,soloa ,levu 7#cac72 and here also palagonite has been produced around the crushed fragments4 ,,coarse ,,zeolitic ,,palagonite-,,tuffs ,these deposits represent coarse kinds of the submarine tuffs of basic glass1 in which the palagonitic change is far advanced1 and where zeolites and at times secondary calcite have been produced in abundance as a result of the alteration4 ,they present themselves in the mass as mottled grey rocks which when examined in thin sections are seen to be composed in great part of fragments of more or less palagonitised vacuolar basic glass1 whilst zeolites are extensively developed in numerous irregular cavities and in the interspaces4 ,although displaying no organic remains1 their submarine character is indicated as at ,nandua by the circumstance of their occurring as horizontal beds overlaid by pteropod-ooze deposits1 or as at ,tembe-ni-ndio by their forming part of a series of horizontal beds with a shelly limestone and a foraminiferous palagonite clay overlying them4 ,the fragments of bottle green basic glass vary usually between #a and #d millimetres4 ,they were originally vacuolar and at times fibrillar from the lengthening out of the minute steam-pores2 but through the palagonitic change these characters have been often disguised1 and it is only at times that the unaltered glass is observed4 ,plagioclase and sometimes augite and occasionally olivine formed phenocrysts in the original glass4 ,the zeolites1 which include chabazite and natrolite1 may be so extensively developed that they make up a fourth or a fifth of the rock mass4 ,one may observe them in cavities where the walls are lined by fibrous natrolite with the cube-like crystals of chabazite occupying the interior4 ,the calcite is usually subordinate to the zeolites1 but sometimes the tuff contains as much as #aj per cent4 of this mineral1 which is evidently of secondary origin4444 ,the history of these tuffs in the district of ,nandua and ,ulu-i-ndali is no doubt applicable to these deposits in other localities4 ,they are the products of submarine eruptions which shattered into fragments the extensive palagonite crusts of flows of basaltic lava4 ,in ,chapter ,,xxiv4 ,i have attempted to show how palagonite is formed on a large scale in the case of such submarine displays of volcanic activity4 ,,chocolate-,,coloured ,,foraminiferous ,,palagonite-,,marls ,we have here hard1 somewhat calcareous1 clay-rocks which consist in great part 7nine-tenths7 of fine palagonite debris with some fragments of minerals and a little fine detritus of semi-vitreous basic rocks4 ,some hand-specimens would be taken for pure palagonite2 but the fragmental nature appears at once in the slide4 ,this is especially the case with a rock exposed in a stream-course near ,rewa on the shores of ,savu-savu ,bay 7see page #ie74 ,the materials composing them are exceedingly fine1 the largest fragments not usually exceeding #b mm4 ,as a rule they contain a little carbonate of lime and sometimes as much as #aj per cent41 whilst a few tests of minute foraminifera are to be noticed in the slide4 ,these deposits are horizontally bedded1 and underlie a pteropod-ooze rock at ,nandua and a shelly impure limestone at ,tembe-ni-ndio4 ,they are not very frequent1 and sometimes approach in characters the volcanic-mud rocks1 which1 however1 are much more mixed in composition4 ,i regard them in the main as sedimentary deposits derived from the disintegration of the palagonitised vitreous surface of a submarine basaltic flow4 ,they pass downward at ,nandua1 as described on page #cde1 into a rock of pure palagonite2 and they are only to be found in localities where basaltic plains or plateaux are covered over with submarine deposits4 ,,acid ,,pumice ,,tuffs ,the general characters of these deposits are described on pages #aj1 #bah1 #bbj1 #bbb1 #bbc1 #bca1 #bcc1 c4 ,such tuffs are restricted to the north-east part of the island east of ,lambasa and ,tawaki1 and are well displayed in the coast cliffs4 ,they are pale yellow or whitish1 and are usually non-calcareous4 ,they are composed of the debris of a vacuolar and fibrillar isotropic glass1 nearly colourless and in some localities altered4 ,small crystals of quartz and of glassy felspar with bits of obsidian 7up to #c mm47 and lapilli of rhyolitic glass are inclosed in them4 ,in places inclosed pieces of coral and coral rock indicate submarine deposition4 ,,chapter ,,xxiv ,,palagonite ,,from the sea-border to the mountain-top in almost every part of the island1 palagonite occurs in a fragmental condition4 ,it is only where tuffs are not found1 as in the mountainous mass of ,seatura1 or where these deposits are formed of acid rocks as in the north-east portion of the island1 that palagonite has not been observed4 ,perhaps1 it is not too much to say that the later if not all the stages in the history of ,vanua ,levu are bound up with the history of this material4 ,in this place ,i will only deal with certain features in the problem connected with the origin of palagonite which seem to receive further elucidation from my observations in this island4 ,the literature is already extensive1 and those interested in the matter will find in ,zirkel's ,petrographie and in the ,challenger ,report on ,deep-,sea ,deposits by ,murray and ,renard a good introduction to the subject4 ,in ,vanua ,levu we are confronted with the same difficulty that has perplexed geologists in various parts of the world4 ,if we expected to find in this island the source of the enormous quantities of the basic glass that are represented by the palagonite of the tuffs1 we should look in vain4 ,basic or basaltic glass usually occurs in agglomerates in the form of tachylytic pitchstones1 as described on page #cab1 and is also found at times in basic pumiceous tuffs1 as described on page #ccc2 but it is far from frequent4 ,palagonite-rock1 that is to say1 a basaltic glass converted in mass into this substance1 never came under my notice4 ,in order to clear the ground for the discussion of my own observations1 ,i will quote from the report on deep-sea deposits above named4 ,fragments of basic glass undergoing the palagonite change are found everywhere in these deposits and especially in the red-clay areas4 ,the hydro-chemical modifications determining the decomposition of these fragments into palagonite1 and at the same time the formation of zeolites1 have likewise resulted in the complete transformation of these lapilli into ferruginous argillaceous matter 7p4 #cji74 ,the authors1 however1 of this report do not attribute the frequent occurrence of fragments of basic glass on the bottom of the ocean to the buoyant powers of basic pumice4 ,unfortunately1 the problem does not permit of such a simple solution4 ,basic volcanic glass1 writes ,prof4 ,renard1 though known only from a few geological formations and from a few eruptions of recent volcanoes at the surface of the continents1 appears in abundance and in most typical form among the products of submarine eruptions1 as if the deep oceans had been in some way specially favourable to the development of this lithological type 7p4 #bii74 ,the palagonite-tuffs of this island are described in detail in ,chapter ,,xxiii41 and a few general remarks are alone needed here4 ,this altered glass enters into the composition1 to a greater or less extent and in varying stages of disintegration1 of nearly all the submarine basic tuffs and clays4 ,in the volcanic muds1 however1 and in the tuffs of mixed character1 which are the prevailing deposits1 it is associated with other components4 ,here the question of the origin of palagonite within the deposit does not as a rule arise1 since there is nothing to indicate that this material was not derived from rocks previously palagonitised1 and the point of main interest is connected with the last stages in the degradation of this substance4 ,there are not a few cases1 however1 where1 unless we assume that the lapilli of vesicular basic glass were ejected in the palagonitic condition from a volcanic vent1 we must apparently regard the alteration as having occurred in the tuff4 ,but even this will prove to be by no means a necessary consequence if it can be shown1 as ,i have attempted to do below1 that the palagonitic condition exists potentially in a particular type of basic glass and that the effect of hydration is not so much to produce but to make evident a condition that was previously latent4 ,it will be therefore of interest to determine whether palagonite occurs in this island independently of the tuff-deposits1 and under such circumstances that it may be regarded as having been produced within the rock-mass4 ,an example is afforded in the case of a basaltic flow near ,soni-soni ,island1 which is fully described on page #ib4 ,whilst the lower part of this flow is composed of a hemicrystalline basalt with scanty olivine1 the upper portion is made of a basaltic glass which has been broken up or crushed 8in situ10 the spaces between the fragments being filled with palagonite4 ,it would seem from the peculiar erosion of the glass fragments that after the crushing a liquid magma occupied the interspaces1 and afterwards solidified and underwent the palagonitic change4 ,illustration3 ,,magma-,,lakelet1 #be mm4 in size1 magnified #bij diameters1 from a basalt at ,navingiri4 ,the groundmass1 which is a smoky devitrified glass containing abundant felspar-lathes1 is coloured black4 ,the magma-lakelet is pale yellow in the slide and displays concentric lines of congelation4 ,it behaves like palagonite4 ,in this connection it is noteworthy that in the sections of the lower hemicrystalline portion of the flow there are shown in the groundmass collections of a palagonitic material forming1 as ,i have termed them1 8magma lakelets0 of microscopic dimensions 7#be mm4 in average size74 ,these 8lakelets0 are irregular in form1 and are not uncommon amongst a certain type of basaltic rocks4 ,one of them is figured above2 and it may be added that they are best examined when displayed in a groundmass containing much smoky1 partly devitrified1 glass4 ,they are usually more or less opaque and reddish-brown or yellowish in colour1 whilst they have often a marked zoned structure1 the concentric bands conforming to the irregular contours of the lakelet4 ,in the least affected stage the zones show fibrous devitrification across their breadth1 but as the palagonitic change progresses the material becomes opaque4 ,in the secondary changes1 such as those associated with the early alteration of the propylites1 these 8magma lakelets0 are the first affected4 ,they then present alternating layers of calcite and viridite and are often bordered by magnetite4 ,if these 8lakelets0 were to be described as collections of residual glass1 the description would be insufficient1 since they may occur in the midst of a smoky1 partially devitrified1 glass4 ,during the last stage in the consolidation of the basaltic mass1 the magma-residuum that still retains its fluidity collects here and there in the crevices of the groundmass1 and forms little pools of usually microscopic dimensions into which the felspar-lathes often protrude from the sides4 ,these little pools or lakelets represent that portion of the yet fluid magma that during the last stage of consolidation is imprisoned in the stiffening mass--like the whey in a cheese--whilst the greater part of it has been squeezed into the cracks of the cooling mass1 as occurs in a dyke-like intrusion below described1 or has been extruded on its surface1 as in the case of the basaltic flow above referred to4 ,as a suggestive instance of the formation of palagonite 8in situ10 ,i will now refer to a basic tuff-agglomerate on the plateau of ,na ,savu 7see p4 #ha7 which is penetrated by veins1 a few inches thick1 apparently composed of a finely brecciated pitchstone-tuff4 ,in the section the material forming the veins is seen to be composed of fragments of basic glass 7carrying porphyritic plagioclase and augite7 which have been crushed in position1 the interspaces being filled up with the finer debris of the glass and of the minerals together with palagonitic material4 ,the glass fragments1 which have lost their sharp edges and angles1 are often palagonitised at the borders1 and we thus get a patch of isotropic brown glass with a yellowish margin formed of a feebly refractive turbid substance4 ,where this border is not so evident1 it is noticed that the edge of the glass is peculiarly eroded4 ,the indication appears to be that the fissures in this agglomerate were filled with a basic magma that after its solidification into a glass was subjected to a crushing process1 and that during this process a partial remelting of the glass took place which resulted in the molecular change characteristic of palagonite4 ,since the unaltered glass-fragments fuse in the ordinary flame1 it would seem that the heat developed during the crushing might be sufficient to partially remelt the glass without affecting the rock penetrated by the veins4444 ,it is of importance to note that in the palagonite-tuffs of the ,canary ,islands the change is often most complete along fissures1 which thus present the appearance of being occupied by veins of pitchstone4#abg ,in this connection allusion may be made to a dyke-like mass of a rubbly semi-vitreous basaltic rock exposed at ,vatu-lele ,bay1 described on page #ahd4 ,it is penetrated in all directions by veins1 #a to #c inches thick1 of a tachylytic glass which begins to fuse in the ordinary flame4 ,the glass is traversed by cracks which sometimes contain palagonite4 ,the basalt1 penetrated by the veins1 has a smoky groundmass displaying imperfect felspar-lathes in a feebly refractive glassy base and containing a few small 8magma-lakelets0 that cannot be distinguished from palagonite4#abh ,near the mouth of the ,narengali valley 7see page #adi7 ,i found what appears to be a palagonite-tuff overlain by agglomerates formed of tachylytic pitchstone and of semi-vitreous amygdaloidal basalts4 ,the tuff consists of fragments of a brown basic glass1 the larger #a to #b millimetres in size1 carrying porphyritic plagioclase1 and fractured in position1 the interspaces being filled with palagonite4 ,the glass fragments possess the eroded margins indicated in the accompanying figure4 ,it may be remarked that this type of tuff differs from that of the prevailing palagonite-tuffs in being rarely vacuolar1 in the absence of marine organic remains1 and in its homogeneous composition4 ,it is described on page #ccd under the head of 8crush-tuffs40 ,whether it is derived from the destruction of a mass of basic glass that had previously undergone crushing and partial palagonisation ,i cannot say2 but its characters point in the direction of this conclusion4#abi ,in the foregoing pages it has been attempted to show that palagonitisation has taken place in the veins of basaltic glass traversing in one case a basic tuff agglomerate and in another case an intrusive basaltic mass1 and that it has also occurred in the upper vitreous portion of a basaltic flow and in the materials now composing a so-called 8crush-tuff40 ,in order to explain this group of facts ,i venture to propose this theory4 ,in certain types of basaltic lava1#acj when cooling and consolidation take place under peculiar conditions1 such as we would expect to find in submarine eruptions1 there is a residuum of the magma with relatively low fusibility that remains fluid after general solidification of the mass is well advanced4 ,as the rock continues to consolidate1 portions of this magma residuum become imprisoned in the mass1 like whey in a cheese1 giving rise to the 8magma lakelets0 above described2 whilst other portions1 during the contraction and fissuring accompanying the cooling process1 are squeezed out into the cracks thus formed1 or are intruded on the surface of the consolidating mass1 as in the case of a submarine lava-flow4 ,this solidified magma-residuum differs from the ordinary basic glass not only in its lower degree of fusibility but in its mineral composition and in its molecular condition4 ,it probably in the first place does not differ much in appearance from the typical glass1 but it is an unstable substance and is capable under certain hydro-chemical conditions of developing the characters of palagonite4 ,illustration3 ,showing fragments of glass with eroded borders and of plagioclase with more even edges in a matrix of palagonite traversed by cracks4 ,the length of the largest fragment is half a millimetre4 ,the glass has been evidently fractured in position and this is true of one of the felspar fragments4 ,it is also apparent that whatever its cause the erosion of the margins of the glass has been produced since the fracture4 ,in those cases where the occurrence of palagonite is associated with evidence of crushing1 the process appears to be in a sense reversed1 since partial palagonitisation of an ordinary basic glass takes place as a result of the elevation of temperature due to the crushing4 ,the heat thus developed is sufficient to partly fuse the glass2 but since it is not great1 it only affects the most fusible constituents1 and the remelted material corresponds therefore to the magma-residuum of the consolidating mass1 which is referred to in the previous paragraph4 ,it has the same unstable characters and the same tendency to assume the palagonitic condition4 ,this theory centres around the relatively low fusibility of the magma-residuum that gives rise to palagonite4 ,this degree of fusibility has yet to be ascertained1 since according to the views here advanced it may even be much lower than that of tachylyte4 ,it is1 however1 noteworthy that the melting-point of tachylyte is far below that of the more crystalline basaltic rocks1 since it can be readily determined1 as ,i have done in the instance of a dyke-like mass penetrated by tachylyte-veins before referred to1 that the veins are composed of a much more fusible material than the rock-mass4 ,from a very crude experiment ,i would infer that the melting-point of ordinary tachylyte is not much above that of lead 7#cce ,c74 ,the fusion-point of an ordinary hemicrystalline basalt1 according to the well-known experiments on the lavas of ,vesuvius and ,etna1 would probably be over #a1jjj degrees ,c4 ,two interesting experiments1 the one artificial1 the other natural1 may be here cited in connection with this view4 ,bunsen#aca more than half a century ago1 as a result of some experiments in which he produced palagonite1 arrived at the conclusion that the tuffs formed of this material are submarine deposits derived from the breaking up of previously formed palagonite-masses4 ,having obtained this substance by placing powdered basalt in an excess of melted potash-hydrate 7,kalihydrat7 and then adding water to the silicate of potash thus formed1 he concluded that palagonite results from the reaction between glowing augitic-lavas and rocks rich in lime and other alkalies4 ,although ,zirkel quotes in this connection the example where this material has been produced in the ,cape de ,verde ,islands by basic lava flowing over limestone1 he rejects ,bunsen's explanation as inapplicable to extensive palagonite districts1 such as occur in ,iceland1 though allowing that it would account for the local production of this substance4 ,i venture to think1 however1 that in these two experiments the general principles involved in the production of palagonite are partly illustrated4 ,we may accept the results of an experiment without acquiescing in its interpretation4 ,as ,i take it1 it is in the partial wet fusion of the powdered basalt that the secret of this successful production of palagonite lies4 ,in both these experiments some of the conditions of a submarine flow have been reproduced4 ,whilst ,rosenbusch established the true character of palagonite as the product of a peculiar alteration of a basic glass1 ,renard pointed out the conditions under which it was most typically and in greatest abundance formed4 ,but ,bunsen was happy in his suggestion that palagonite-tuffs are submarine deposits derived from the breaking up of previously formed palagonite masses4 ,the question thus resolves itself into one concerning the conditions of submarine eruptions and the behaviour during consolidation of a submarine basaltic flow4 ,in the nature of things the field of investigation is mainly restricted to the examination of ancient submarine basaltic flows that have been raised above the sea4 ,a remarkable series of beds exposed in a stream-course below the ,nandua tea-estate may be here described in connection with the question of the origin of palagonite formations4 ,as observed on page #hf1 this locality lies on the flanks of a basaltic plateau1 which are incrusted with recent submarine deposits4 ,a pteropod-ooze1 containing also the tests of large and small foraminifera and the shells of small bivalves1 is displayed on the sides of the stream-course for the first #aej feet of the descent4 ,below this1 as shown in the diagram1 is a declivity with a drop of #fj or #gj feet where there is a waterfall4 ,horizontal beds of the pteropod-ooze rock are exposed in the upper-third of this declivity2 but below1 they pass into a chocolate-coloured marl-like deposit also horizontally bedded1 and sometimes having a banded appearance from the alternation of layers of different degrees of fineness4 ,this rock contains #e or #f per cent4 of carbonate of lime and incloses a few scattered tests of minute foraminifera of the 8,globigerina0 and 8,nodosaria0 types4 ,in the slide the rock appears to be of massive palagonite inclosing a few felspar-lathes #a to #c mm4 in length1 and exhibiting a zeolite and calcite in the crevices and cracks4 ,but it was not until ,i had discovered the tests of the foraminifera and had observed some fragments of larger crystals of plagioclase and a little detritus of a semi-vitreous basaltic rock that its clastic character was disclosed4 ,the palagonite change has here to a great extent disguised the character of the deposit4 ,this palagonite-marl formation is #bj or #cj feet in thickness4 ,it passed downward into a reddish-brown rubbly unstratified rock which falls to pieces in one's hands1 breaking up into little cube-like masses an inch or two across4 ,these masses display in their interior a radiate prismatic structure2 but after drying they crumble into small fragments exhibiting the same minute prismatic structure1 the miniature prisms being about a millimetre in diameter4 ,fine cracks1 filled with calcite and a zeolite1 traverse this rock in all directions1 and no doubt this peculiar structure arises from shrinkage4 ,my idea that ,i was dealing with a clay-rock affected by the proximity of an igneous intrusion was dispelled when the powdered material presented itself as pure palagonite with scarcely any mineral fragments4 ,unlike the marl above1 it does not effervesce with an acid2 and appears as a mass of compacted minute fragments of basic glass converted into palagonite1 which is seemingly non-vacuolar1 and containing about #ae per cent4 of water4 ,in connection with the diagram it should be remarked that ,i did not find the palagonite-rock actually passing down into the basalt which1 however1 is exposed in the river-bed below4 ,the whole district is characterised by columnar basalt1 and the series of deposits here described have been formed on the flank of the great basaltic table-land of ,wainunu4 ,it is noteworthy that in the uppermost deposits of the pteropod-ooze palagonite forms a noticeable proportion 7#aj-bj per cent47 of the residue2 and perhaps most of the fine clayey material is thus derived4 ,as noted on page #cba1 minute pellets of pure palagonite are not infrequent in the residue4 ,probably about #ij per cent4 of the underlying marl consists of palagonite4 ,in the lowest palagonite-rock the proportion would be quite #ih per cent4 ,illustration3 ,diagram showing the succession of deposits below the ,nandua tea-estate4 ,the total thickness is about #bej feet4 ,the figures refer to the proportion of palagonite4 ,whilst it is apparent that we have represented in this series the covering of a submarine basaltic flow with submarine deposits1 it is also evident that the mode of junction between the flow and the overlying deposits is of an unexpected nature4 ,before drawing any inferences1 it is necessary to point out that when we begin on priori grounds to frame our notions as to the course of events on the surface of a submarine basaltic flow1 we are entering a little known region of inquiry4 ,i would1 however1 suggest in the light of the theory before advanced1 the following explanation of the appearances presented by this series4 ,during the consolidation of the flow much of the magma-residuum that still retained its fluidity was extruded on the surface1 where after solidification it became palagonitised4 ,according to my view this would be the typical behaviour of submarine basaltic flows2 but1 owing to the unstable and perishable nature of the palagonitic crust of the flow1 it would be rarely preserved in upheaved volcanic regions4 ,there would probably be1 as in the case of the ,nandua series1 no sharp line to be drawn between the palagonite-crust and the deposits subsequently covering it1 deposits indeed that would derive no inconsiderable proportion of their materials from the disintegration of the crust itself4 ,during and after the emergence of such a district of submarine eruptions the unstable palagonitic crust would be further subjected to the hydration resulting from weathering and similar agencies2 and as a result of its final degradation there would often alone remain a bed of reddish argillaceous material4 ,in concluding these remarks on palagonite the following summary of the principal points here dwelt upon may be added3 7a7 ,the basic glass1 that undergoes the palagonitic change1 is the vitreous form of the magma-residuum that in a particular type of basalt and under certain conditions remains fluid after the mass of the rock has solidified4 ,during the last stage of the consolidation it is in part imprisoned in the 8magma-lakelets0 of the groundmass2 whilst the rest of it is squeezed into cracks and fissures1 or extruded on the surface of the flow4 7b7 ,this glass differs from ordinary basic glass in its molecular condition1 its mineral composition1 its low degree of fusibility1 and in its unstable character4 7c7 ,the formation of palagonite in connection with the crushing of a basic glass is to be explained by the hypothesis that the heat developed during the crushing is sufficient to partially re-fuse the glass1 the material thus produced corresponding to the magma-residuum of low degree of fusibility1 which is above referred to4 7d7 ,in submarine eruptions are to be found the conditions favouring the production of palagonite on a large scale4 ,in the case of such basaltic flows it is probable that their upper portions are formed entirely of palagonite arising from the alteration of a vitreous magma-residuum extruded on the surface in the manner above described4 ,such a crust1 as a result of shrinkage and other processes1 would probably present itself to the geologist as a somewhat friable material1 passing gradually into the overlying submarine deposits4 99 99 99 99 99 ,note on the type of basalt found associated with palagonite4 ,the type is characterised1 it would appear1 rather by its structural features than by its mineral composition4 ,it is the basalt of ophitic or semi-ophitic habit that would seem to be usually associated with palagonite2 and since this habit is as a rule to be found where the groundmass displays large felspar-lathes in plexus arrangement1 coarse augites1 and at least a fair amount of smoky glass1 it follows that a hemi-crystalline1 ophitic or semi-ophitic1 doleritic basalt is the type to be associated with palagonite4 ,this is the type of rock that forms the lower part of the basaltic flow near ,kiombo1 the upper part of which is largely palagonitic4 ,to this structural type also belong most of the basalts in my collection where palagonite exists in the form of 8magma-lakelets0 in the groundmass4 ,these 8lakelets0 are almost diagnostic of this type of basalt4 ,here also belongs the famous globular basalt of ,acicastello on the coast of ,sicily4#acb ,in such rocks the felspar-lathes form a mesh-work and vary usually in average length between #a and #c mm4 ,the augites of the groundmass1 typically semi-ophitic1 range up to #a mm4 in size4 ,they are always large1 that is1 over #jc mm41 and this coarseness is another important indication4 ,,note ,,on ,,the ,,changes ,,produced ,,through ,,the ,,hydration ,,of ,,palagonite4 ,most of that which is detailed below is not according to my views palagonitisation1 but the effect of hydration in the disintegration of this material4 ,the initial molecular condition and the other characters which represent potentially the palagonitic change are not connected with hydration2 but are concerned with the causes before explained that led to the formation of a basic glass of such an unstable constitution4 ,indeed1 there is good reason to believe that the changes to be now described may be observed under the ordinary influences of weathering in a wet region4 ,the early stages of alteration are well displayed in some of the tuffs formed mainly of basic vacuolar glass1 the submarine character of which is often indicated by a few tests of foraminifera4 ,whilst the glass retains its original bottle-green colour1 it loses the clean sharp conchoidal edges and displays rough and uneven or granular borders4 ,with a high power the surface of the fragment is seen to be minutely pitted or pock-marked in places1 the shallow circular pits1 less than #ja mm4 in diameter1 being sometimes arranged in a row like a number of overlapping rain-prints4 ,this process proceeds until all the surface is affected1 and from this cause there is often an appearance of polygonal markings4 ,the pock-marking1 however1 continues2 and as the pits encroach more and more on each other an irregularly wrinkled rough surface results4 ,up to this time the glass has retained much of its original colour2 but its clearness is replaced by turbidity1 and collections of very minute rounded1 rod-shaped1 and irregular granules1 composed of a colourless feebly polarising material1 are displayed here and there in its substance1 whilst some of the previously empty vacuoles are now filled with water4 ,in the next stage the hydration of the iron-oxides begins1 and the glass becomes opaque and yellowish or reddish-brown1 and has a more granular appearance1 polarising feebly4 ,cracks now traverse the substance1 and penetrate into the vacuoles1 which1 as they become filled with the alteration products1 whether palagonitic1 zeolitic1 or siliceous1 become ruptured and curiously distorted4 ,the hydration and consequent disintegration continue until the deep stain of the iron-oxide is removed1 and a semi-pulverulent whitish material remains4 ,this is the history of the little bleached powdery patches so common in basic tuffs1 each representing originally a lapillus of basic pumice4 ,this powder when examined with the microscope is shown to be made up of fine granular and tubercular materials which lose much of their distinctness when mounted in ,canada balsam4 ,it is not affected by boiling in ,h,cl1 and contains usually an abundance of minute siliceous oval amygdules that have been freed in the last stage of the disintegration of the palagonite4 ,such is the story of the degradation of the palagonite daily in operation in the basic tuffs of this island4 ,from this source is doubtless derived much of the finest constituents of the submarine clays so common over ,vanua ,levu4 ,supplementary note on the occurrence of palagonite in the glassy matrix of pitchstone-agglomerates and in rubbly pitchstones4--,in my last revision of the proofs ,i find that ,i have not laid sufficient stress on the production of palagonite under these conditions4 ,the evidence of crushing is often very evident1 and especial references to this point will be found in the index under 8,pitchstone10 and on page #ccd under 8,crush-tuffs40 ,,chapter ,,xxv ,,silicified ,,corals ,,and ,,flints ,,silicified corals1 together with siliceous minerals 7quartz1 chalcedony1 jasper1 c47 and siliceous concretions are evidently widely distributed in these islands4 ,kleinschmidt in his journal refers to large blocks of flint on the island of ,ono1 from which the natives used to obtain their musket-flints1#acc and he collected from this island as well as from ,viti ,levu1 ,ovalau1 c41 numerous specimens of these and other siliceous minerals and rocks1 such as hornstone1 chalcedony and jasper1 which were examined by ,wichmann and described in his paper4#acd ,mr4 ,andrews observed silicified corals on the summits and higher slopes of ,vanua ,mbalavu4#ace ,the ,fijian name for flints1 8ngiwa0 7thunderbolt7 or 8vatu-ngiwa0 7stone-thunderbolt71 affords a good instance of that curious superstition connected with the origin of these stones1 which came also under my notice in the ,solomon ,islands1#acf and in fact is widely spread4 ,in ,vanua ,levu these siliceous rocks and minerals are in places abundant4 ,they are especially frequent on the surface of the extensive low plains on the north side of the island which constitute the basins of the ,sarawanga1 ,ndreketi1 ,wailevu1 and ,lambasa rivers2 but it is in the low-lying district of ,kalikoso1 in the north-eastern part1 that they exist in the greatest quantity4 ,they do not occur usually at greater elevations than #cjj feet1 and are found as a rule at much lower levels4 ,it must be understood that reference is not here made to quartz-veins1 such as are found in certain localities and of which mention is made on pages #ajf1 #aaf4 ,it is not with the ordinary products of contact or general metamorphism that we have here to deal2 but with the remarkable surface-collections of silicified corals1 nodules and flints of chalcedony1 fragments of white quartz-rock1 bits of jasper1 and certain curious siliceous concretions1 that occur often in association with fragments of limonite in these low-lying regions4 ,all the siliceous materials above named have1 as the microscope indicates1 a common character1 chalcedonic silica in a greater or less degree being the basis of all of them1 whether coral1 flint1 white quartz-rock1 or jasper4 ,it soon became apparent whilst examining these districts that one general condition prevailed whilst this extensive deposition of silica and the formation of the beds of limonite were in progress4 ,it cannot1 however1 be pretended that these processes are actually in operation on the plains now4 ,except in the case of the limonite in a few localities the processes have been suspended2 but they were in active operation not long ago3 and an examination of the general characters of the districts will probably disclose some of the conditions under which these products have been formed4 ,on the surface of the ,kalikoso plains1 where these materials are most abundant1 we find silicified corals associated with fragments and nodules of chalcedony1 flints1 white quartz-rock1 limonite1 concretions of carbonate of iron1 c41 in the low-lying and often swampy district around the fresh-water lake1 the whole region being only elevated between #bj and #fj feet above the sea4 ,this is an area of decomposing acid rocks 7quartz-porphyries1 trachytes74#acg ,on the other hand in most of the regions where these materials occur on the surface we have areas of basic rocks 7basalts and basaltic andesites7 incrusted in places with submarine tuffs and foraminiferous clays1 the volcanic rocks undergoing extensive disintegration4 ,such for instance are the ,lekutu1 ,sarawanga1 ,ndreketi1 and ,lambasa plains4 ,in the ,lambasa plains1 which are described in this connection on page #aci1 we find besides the corals and flints and nodules of chalcedony1 fragments of jasper4 ,in the ,sarawanga and ,lekutu lowlands1 we find silicified corals and limonite2 but here the crystallised silica of the corals contains a large quantity of water1 whilst in its lesser degree of hardness and in its low specific gravity it comes near to semi-opal4 ,in these and other localities1 as in the level country around ,ndranimako on the right side of the ,yanawai estuary1 we find curious concretions of the same kind of hydrous silica more or less crystalline4 ,these concretions are described below4 ,it may be remarked that nearly all the districts in which the silicified corals and concretions1 siliceous minerals1 and limonite occur1 are scantily vegetated 8talasinga0 lands#ach with reddish soil4 ,except in the instance of the ,kalikoso plains1 the swamps and lakes have as a rule long since disappeared1 their sites being alone indicated by the limonite on the surface4 ,in the ,mbua plains1 however1 there are occasional small ponds and swamps1 and there is no doubt that the limonite so bountifully represented on the dry districts is still in process of formation4 ,before drawing some general inferences as to the conditions under which this deposition of silica and iron took place1 ,i will refer to the characters of the materials thus produced4 ,the silicified corals include massive corals of the ,astraean and 8,porites0 kinds and branching specimens of the ,madrepore type or habit4 ,the former are rarely larger than #g or #h inches across and are merely fragments4 ,the latter are always portions of branches1 never exceeding #c or #d inches in length4 ,in the last case it is sometimes possible to show1 as in the case of a specimen found on the ,kalikoso plains1 that before silicification occurred the dead fragment of branching coral had been extensively eroded by solvent agencies and had been penetrated by burrowing molluscs4 ,the larger blocks of massive corals have usually been extensively chipped by the natives in obtaining flints4 ,in past times they were carried from one place to another1 the result being that occasionally they were brought to me in the mountain-villages1 all showing evidence of their having supplied flints to a past generation4 ,these corals are as a rule completely silicified4 ,when a massive specimen is broken across it is not infrequently found that whilst the coral structure is preserved in its outer part1 the inner portion is composed of a compact seemingly structureless mass of bluish-white or pale-grey flint1 which has the characteristic microscopical appearance of chalcedony and a specific gravity of #bei4aci ,it is from the more compact parts of the silicified massive corals that the 8worked0 flints found on the surface were obtained1 though in some of them1 as in the case of a 8scraper0 in my collection1 the traces of coral structure are still apparent to the eye4 ,wichmann observed in the case of the silicified corals from ,fiji that the whole petrifying process appears to consist in the saturation of the coral with silica1 the coral structure being usually distinct1 whilst the septa1 often still calcitic1 show the points of the calcite crystals projecting into the chalcedony which forms the mass4 ,lime however rarely occurs in the silicified corals of ,vanua ,levu4 ,it was only in the case of one or two localities that the corals displayed any effervescence with an acid4 ,in the microscope slide the massive specimens appear to be entirely of chalcedonic silica1 the outlines of the cells and of the septa being indicated by ferruginous material4 ,in a specimen of ,porites by my side the crystallization of the silica has advanced beyond the chalcedonic stage and the coral is composed entirely of minute quartz-crystals1 #b to #d mm4 in size1 often irregular1 but sometimes forming doubly-terminated prisms4 ,this has produced a somewhat crumbling rock1 which is easily powdered by the finger2 and in this case1 therefore1 the complete crystallization of the silica is resulting in the disintegration of the silicified coral4 ,the ordinary silicified massive corals of ,vanua ,levu1 where the replacement by chalcedonic silica is complete1 though the structure is preserved1 have a hardness of about #f and a specific gravity of #bed1 and yield but little water in the closed tube4 ,occasionally1 however1 as in the ,sarawanga plains and in the ,lekutu lowlands we find silicified fragments of branching corals which are easily scratched with a knife and have a hardness of #c to #d and a specific gravity of #bc4 ,the fractured surface is milk-white or reddish1 and looks like semi-opal4 ,when powdered and heated in a closed tube1 the material loses one fourth or one fifth of its weight of water1 the finest dust 7passing away in the steam7 being deposited on the sides of the glass4 ,in the slide there is displayed a finely granular crypto-crystalline structure with in places a somewhat coarser quartz-mosaic1 whilst chalcedonic quartz fills minute cracks in the mass4 ,no coral structure is preserved4 ,numerous points coloured by iron oxide occur in the section1 and minute dust-like inclusions abound1 which are doubtless water-pores4 ,i have described on a later page certain concretions found associated with these silicified corals which though formed of the same crypto-crystalline hydrous silica1 are apparently silicified portions of nullipore-rocks4 ,the fragments of flint that occur commonly on the surface in these districts are1 as above remarked1 derived from the hard silicified coral-masses4 ,nodules of chalcedony1 having all the appearance of having originated in cavities1 are also very frequent4 ,they may take the mamillary1 agate1 or onyx form1 some of the agates when polished making beautiful specimens4 ,these nodules are of all sizes up to #c or #d inches across4 ,some of them are hollow and lined with clear quartz-crystals1 whilst with others the cavity may be completely filled by interlocking quartz-crystals4 ,the outer surface of one of the agates displays markings showing in relief casts of the 8cups0 of a minute-celled coral4 ,mingled with the other siliceous materials on the surface of the ,kalikoso and ,lambasa plains are found fragments of a whitish quartz-rock1 having a specific gravity of #bec-beg1 being therefore markedly lighter than quartzite 7#bfc-bfg7 which it somewhat resembles4 ,it usually occurs as small hand-specimens2 but in the vicinity of ,mbati-ni-kama ,i found blocks1 #ab to #ae inches across1 lying in the river-bed4 ,under the microscope it displays a fine radio-globular aggregate of chalcedonic quartz4 ,mention has already been made of the siliceous concretions1 composed mainly of hydrous crypto-crystalline silica1 which are associated with the silicified coral fragments formed of the same kind of silica on the surface of the plains of ,mbua1 ,lekutu1 and ,sarawanga4 ,they also occur in the ,ndranimako lowlands on the right side of the ,yanawai estuary1 and in the more elevated inland districts of the ,wainunu and ,na ,savu table-lands at elevations of #fej to #ggj feet above the sea4 ,they take the form of irregular nodules1 or of flat uneven 8cakes10 usually two or three inches in size4 ,they are as a rule reddish1 but sometimes pink and white4 ,their hardness is only #c to #d1 and they are easily scratched with a knife2 and when powdered and heated in a closed tube1 they lose about one fourth of their weight of water4 ,under the microscope they exhibit a grey crypto-crystalline groundmass showing very finely granular crystalline silica with the cracks and small cavities filled with more brightly polarising chalcedonic quartz4 ,but they differ as regards their other components and also in their mode of occurrence2 and it is highly probable that the history of their origin is not always the same4 ,those associated with the silicified corals on the ,sarawanga and ,lekutu lowlands show no structure in the slide that gives me a clue as to their origin2 but they may perhaps represent old ,nullipore nodules4 ,those around ,ndranimako are coloured deep red2 and whilst some give no indication as to their source1 others are transitional in character1 and display in the sections traces of the vacuolar semi-vitreous basic rock of which the original fragment was composed4 ,the same red siliceous concretions form the pebbles and gravel in the stream-beds on the surface of the ,na ,savu table-land1 #gjj feet above the sea4 ,these red flint-like nodules of ,ndranimako and ,na ,savu somewhat resemble the jasper of the island2 but they are sharply distinguished by their microscopic characters1 by being easily scratched with a knife1 and by the large amount of water which they contain4 ,rolled stones1 which were found in the shallow stream-courses on the surface of the ,wainunu table-land #gej to #hjj feet above the sea1 exhibit in the sections1 in spite of the general silicification of the groundmass1 the outlines of the original phenocrysts of felspar1 and abundant skeletal magnetite rods1 such as would characterise a semi-vitreous basic rock4 ,it is evident that in the basaltic districts of the ,na ,savu and ,wainunu table-lands these concretions have been formed under certain conditions by the decomposition of the silicates of basic rocks4 ,but these conditions do not exist now2 and ,i infer that the silicified rocks1 which occur only in fragments on the surface1 represent the silicification that occurred during the emergence of the land ages since4 ,occasionally one comes upon in the mountain districts1 as in the vicinity of ,ndrawa1 large solitary blocks #b to #d feet across of a whitish chert-like rock which has a hardness of #e or #f1 the harder variety having a specific gravity of about #beh and the softer1 which yields a fair amount of water1 a specific gravity of about #bdf4 ,i noticed such solitary masses also on the ,mbua plains4 ,the first-named locality is dacitic and the last basaltic4 ,they exhibit in the slides a patchy appearance1 showing in some places finely granular crypto-crystalline silica and in others a coarser mosaic of chalcedonic quartz4 ,apart from the absence of any definite coral structure1 ,i can only surmise that they were originally masses of reef-limestone4 ,their elevation even in the mountainous districts was not over #djj or #ejj feet above the sea4 ,fragments of jasper1 which are associated with nodules of chalcedony and silicified corals in the ,lambasa plains1 are also to be found as pebbles and small blocks in the mountain streams of the ,ndrawa1 ,ndrandramea1 and ,lea districts1 together with bits of chalcedony and quartz-crystals4 ,they do not occur1 or are of rare occurrence1 in the recently emerged ,kalikoso district and probably belong to an earlier stage in the history of the island's emergence from the sea4 ,they have a hardness of #f to #g1 not being scratched by a knife1 and a specific gravity of #bfe to #bgj2 whilst but little water is given off in the closed tube4 ,they are a variety of chalcedony1 rendered opaque by the large quantity of red oxide of iron that it contains1 and are really1 therefore1 iron-flints4 ,the microscopical section in one case displays in the clear spaces a beautiful globular aggregate1 each globule having a nucleus of the iron oxide and giving a black cross in polarised light4 ,in another case the globular structure is less perfect1 and the chalcedonic groundmass is penetrated by a multitude of fine cracks filled with iron oxide4 ,the deposits of limonite vary in character in different localities1 and evidently they have not all the same history4 ,the soil of the low-lying plains around ,wai-ni-koro and ,kalikoso1 and especially in the vicinity of the fresh-water lake1 is often coloured a deep ochreous red4 ,small fragments of an earthy yellowish-brown limonite occur on the surface in quantity and are particularly abundant near the lake4 ,they yield much water when heated4 ,in some places in this district1 as in the country traversed between ,wai-ni-koro and ,kalikoso1 the surface is strewn with a number of small round concretions of the size of small marbles 7#f to #ab mm47 which are composed of a mixture of carbonate of iron and limonite1 but show no recognisable structures4 ,they are somewhat friable and give off much water when heated1 whilst they effervesce freely in hot hydrochloric acid4 ,it is probable that some of the earthy limonite of the ,kalikoso district contained originally iron carbonate and has been produced from concretions such as ,i have just described4 ,the variety of limonite found in fragments on the surface of the plains of ,mbua1 ,lekutu1 and ,sarawanga1 at elevations usually of #ajj or #bjj feet above the sea1 is a heavy compact kind with a specific gravity of #c to #ce1 and closely resembling red hematite4 ,since1 however1 it is lighter in weight and still contains a little water1 it may be regarded as in the transition stage4 ,it occurs as portions of cake-like masses varying usually from a third of an inch to rather over an inch in thickness4 ,as a rule it is found in localities where no lakes or swamps now exist and may be associated1 as in the ,sarawanga and ,lekutu plains1 with silicified corals and siliceous concretions2 but in some cases1 as in that of the ,mbua plains1 ponds and swamps are still scantily represented in the vicinity1 and the water of the stagnant streams is deeply coloured with iron 7see page #ef74 ,ironstone gravel occurs in great quantity strewn over the surface of the basaltic table-lands1 especially in the case of that between the ,wainunu and the ,yanawai rivers4 ,the smaller gravel varies usually between one eighth and one third of an inch in size1 the larger fragments being about an inch4 ,the specific gravity is #ca to #cb4 ,the material forming the finer gravel dissolves with but little effervescence and scanty residue in hot hydrochloric acid2 it gives off water and is evidently impure limonite4 ,the larger fragments1 #a to #b inches in size1 represent the partial conversion into limonite of a basic volcanic rock with much glass in the groundmass which formed probably the surface of the basaltic flows of the plateaux4 ,there must be an enormous amount of this iron-stone in the island4 ,the finer gravel has a concretionary character1 some of the pieces appearing like bits of stick that have been converted into limonite4 ,it seems to have been formed during the disintegration of the rock on the moist surface of these densely wooded basaltic plateaux2 the process was not accomplished in ponds or swamps1 but was carried out on ordinary damp ground4 ,it must be observed in the above connection that the soil in the areas of basalt and basaltic andesites1 which occupy a large portion of the surface of the island1 contains a large amount of fine magnetic iron-sand4 ,after heavy rains the foot paths glisten with this fine material which has been washed out on the ground4 ,this is especially the case in the extensive scantily vegetated 8talasinga0 regions where the basaltic rocks are disintegrating for a considerable depth4 ,the river-sand of these areas1 after a little washing1 yields about #ge per cent4 of magnetic iron grains which give in some cases a slight titanium reaction4 ,the amount of magnetic iron-sand in these rivers1 as for instance in the ,yanawai and the ,wainunu1 must be very great4 ,in the beds of the small sluggish streams on the surface of the ,wainunu table-land the amount is also very large4 ,any explanation of the origin of the extensive silicification evidenced by the occurrence of silicified corals and siliceous concretions on the surface in various parts of the lower regions of the island will have to include that of the formation of the limonite fragments so often accompanying them4 ,the necessary conditions would1 ,i think1 be afforded by an emerging land-surface during the consolidation of the exposed calcareous muds and the subsequent draining of the new surface4 ,on parts of the newly formed land1 there would follow the successive stages of sea-water1 brackish1 and fresh-water swamps1 such as are clearly indicated by the abundance of silicified coral fragments that strew the surface of the low-lying and often swampy districts around the fresh water lake of ,kalikoso4 ,in such a locality as that of ,kalikoso1 there were no doubt at the time of the emergence large tracts covered with chalky calcareous mud derived from reef-debris2 and it was during the consolidation of this mud in the recently reclaimed area that the fragments of coral imbedded in it became silicified4 ,in these cases where the imbedded corals were already much decayed1 it is probable that the empty cavities thus produced were filled with silica1 and that in this manner the nodules of chalcedony were produced4 ,here and there a pebble or a larger block of a volcanic rock would have been inclosed in the mud2 and in this case also silica largely replaced the original material of the stone4 ,i imagine that with the evaporation of the water in the mud during the drying and consolidating processes the proportion of silica in solution would attain a degree of super-saturation and that the silicification would hence be brought about4 ,with the consolidation of the mud the deposition of silica ceased2 and in the case of any coral fragments1 where the transformation was not completed1 decay would often commence4 ,in the instance of some bits of coral found imbedded in foraminiferous mud-rock in the ,lambasa plains the process of the change had been suspended1 and the fragments were in a state of decay1 and coloured red by iron oxide4 ,if silicification occurred in a submarine deposit only after it became a portion of an old land-surface we ought not to find incompletely silicified corals inclosed in it4 ,for these reasons ,i do not consider that silicification would occur in the case of submarine deposits long after they have been raised above the sea4 ,on the other hand it would seem that the deposition of silica in the hard parts of dead organisms does not proceed in the shallow-water calcareous mud of coral reef coasts previous to emergence4 ,silicified corals have never as far as ,i know been found under such conditions4 ,nor could the coral fragments now lying on the ,kalikoso plains1 often only elevated some #bj or #cj feet above the sea1 have undergone this change whilst exposed on the land-surface as they now lie4 ,they must have been inclosed in some material containing abundant free silica2 and it is reasonable to suppose that this material was the chalky mud of the reef-flats on which they once lived4 ,if this is admitted1 then it follows that since1 as above assumed1 silicification does not occur in such a mud either before upheaval or long after it has been raised above the sea1 it must take place in the intermediate period1 or in other words whilst the recently exposed submarine deposits are consolidating and drying4 ,several objections at once occur with reference to this explanation of the silicification of corals in this island2 but much more investigation is needed to establish any view on the subject4 ,in the ,kalikoso plains1 however1 we have a critical locality for the pursuit of this inquiry4 ,concretions of carbonate of iron and deposits of earthy limonite are here associated with silicified corals on the surface of a level and often swampy district around a freshwater lake in a region which is only elevated #bj to #fj feet above the sea4 ,we are dealing here with an area of land that has emerged in comparatively recent times as far as the history of the island is concerned4 ,the element of time is limited1 and the problem is not complicated1 as it would be in the case of an old land-surface1 raised some hundreds of feet above the sea1 by the intrusion of many other disturbing agencies4 ,nature has simplified matters here for the inquirer4 ,the evidence of recent emergence with regard to the whole island is discussed in ,chapter ,,ii41 and need not be again referred to here2 whilst the general description of the ,kalikoso district is given in ,chapter ,,xvi4 ,in this connection it may be remarked that before their emergence the ,kalikoso plains were covered by the waters of a large irregular sea-water lagoon or lake1 which though more or less surrounded by hills had free communication with the sea on the north along the line of the passages now occupied by the ,wai-ni-koro and ,langa-langa rivers4 ,both massive and branching corals then thrived in the waters of the lagoon4 ,there is no ground for supposing that during the emergence there was an intermediate stage characterised by brine-ponds and salt-swamps4 ,the drainage from the slopes of the mountains to the southward would have prevented it4 ,whilst this change of level was in operation1 brackish water collected in the deeper part of the original lagoon1 forming a lake which as evidenced by the present distribution of limonite on the surface of the plains was then far larger than it is now4 ,as the plains became exposed large flats covered with chalky mud in which dead corals were more or less imbedded were bared2 and there and then as the drying and consolidation proceeded silicification took place in the manner before surmised4 ,this deposit was of no great thickness1 and has been since removed by the denuding agencies1 whilst the silicified corals remain behind4 ,when in the ,solomon ,islands ,i was unable to find the source of the chalcedonic worked flints of such frequent occurrence in that region4 ,in my general work on those islands 7pp4 #gg to #hj7 reference is made to this subject4 ,it will probably be shown that there as in ,fiji most of the flints are silicified corals4 ,in conclusion it may be remarked that those who object to the explanation of the origin of silicified corals advanced in this chapter will be able to find support for their alternative hypothesis in many facts detailed in these pages4 ,vanua ,levu1 for instance1 abounds in hot springs2 and ,mr4 ,andrews might regard this fact as giving strength to his view that the silicified corals of ,vanua ,mbalavu in this group owe their condition to the agency of superheated water derived from volcanic rocks1 more especially since hot springs are found on the island4 ,such an explanation could not1 ,i think1 apply to the extensive area of the ,kalikoso plains where the silicified corals are associated with limonite on the surface of a recently emerged area4 ,if these changes had been induced by hydrothermal action1 one ought to find evidence of this in those localities in ,vanua ,levu where the hot springs issue from foraminiferous clay deposits1 as in the vicinity of ,vuni-moli2 but no traces of such a transformation came under my notice4 ,wichmann does not advance any explanation of the silicification of the corals2 but he considers that the 8hornstones10 which he obtained from ,fiji1 rocks corresponding to the chert-like rocks described by me on page #cee1 are the products of disintegration of the basic andesites4 ,i have already pointed out that certain siliceous nodules have probably this origin4 ,it is also likely that some of the jasper of ,vanua ,levu has been thus formed4 ,note on a silicified ,fern ,rhizome4--,this is a specimen1 about three inches long1 picked up by a native in a stream near ,sueni in the centre of the island4 ,it has the appearance of being a portion of the stem or rhizome of a tree-fern1 and is permeated in its entirety by chalcedonic quartz1 the fibro-cellular structure being still preserved4 ,no other specimen of the kind came under my notice4 ,the probability of the occurrence of silicified plant-remains in the pumice-tuffs of the ,undu ,promontory is pointed out on page #bcc4 ,,chapter ,,xxvi ,,magnetic ,,rocks ,,the literature on the subject of the magnetism of rocks is very extensive1#adj and even if ,i was capable of doing so1 any attempt to deal generally with this complicated phenomenon would be out of place here4 ,zirkel in his characteristically thorough fashion has reviewed the subject in his general work on petrography1 but since the date of the last publication of that book1 #ahic-id1 the literature has been much increased and the subject has from time to time been opened up in scientific periodicals1 occasionally in ignorance of the labours of those that have gone before4 ,here1 the local magnetisation of rocks is alone considered1 the general question of earth magnetism not being entered into4 ,according to ,zirkel one of the earliest known observations of this phenomenon was made by ,bouguer1 the ,french geographer1 whilst he was engaged in the measurement of a degree of the meridian in the vicinity of ,quito in #agdb4 ,alexander von ,humboldt1 however1 was one of the first to attract general attention to this subject by the announcement of his discovery in #agif of a 8great magnetic mountain0 in the heart of ,germany4 ,he was then director-general of the mines in two ,franconian principalities2 and in order to awaken the interest of ,german physicists and mineralogists in this matter1 he announced his discovery with an air of mystery1 and did not disclose the locality for many months4 ,he then placed his specimens in the mining-office at ,bayreuth to be sold at so much by weight for the relief of poor miners4 ,his plan succeeded1 and this young savant who had yet before him his great career1 had soon enlisted the interests of several of the noted scientific men in ,germany1 including ,werner the mineralogist1 ,voigt the mathematician1 ,blumenbach the naturalist1 ,charpentier1 and others4 ,the amount of attention that this subject then excited can be inferred from the pages of the 8,intelligenzblatt der ,allgemeine ,literatur-zeitung0 for #agif-agig and from the contemporary publications4 ,it has been almost forgotten now1 and the matter is indeed often approached 8de novo40 ,however1 although by these means the data became largely increased1 no generally accepted explanation resulted4 ,opposing views continued at various times to be advanced2 and it has only in recent years come to be recognised that the magnetic polarity#ada of rocks in exposed situations1 as in the mountain-peak or in the crested spur1 often arises from atmospheric electricity independently of the inductive action of terrestrial magnetism4 ,this is the conclusion to which the later evidence given by ,zirkel is directed and was that which ,oddone and ,sella formed from their study of the magnetic rocks of the ,central ,alps4 ,it is not1 however1 always necessary to suppose that the affected rocks have been struck by lightning1 although ,sella and ,folgheraiter have shown that this is the result of such a contact4 ,they may be found1 as indicated by ,mr4 ,harker1 in mountainous localities where thunder-storms are remarkably rare1 and where the peaks act1 it is suggested1 as natural conductors4 ,it is easy to show1 remarks the same author1 that no lapse of time is required for rocks in exposed situations to become magnetised4 ,the stones of cairns erected a few years before on the mountain-tops of the ,isle of ,skye become invariably highly magnetic2 whilst the loose stones lying on the ground display this property to a much less degree4 ,nor is it requisite that the rocks affected should be basic volcanic rocks4 ,it has long been known that granites1 trachytes1 c41 can possess magnetic polarity#adb2 and the existence of this quality among acid volcanic rocks is well shown in the case of the dacites in ,vanua ,levu1 rocks which compose some of the isolated mountain-peaks4 ,one finds occasional reference to the highly magnetic character of the rocks in oceanic islands of volcanic origin1 but the nature of the property is not always described2 and it is sometimes not possible to gather from the data given whether the magnetism affects the whole mountain mass1 when it would be of the regional kind1 due probably to induction1 or whether it is the simple magnetic quality that almost all basic volcanic rocks possess on account of the fine magnetite disseminated through the rock1 or whether there is evidence of a deposit of magnetite in the vicinity1 or whether it is a mere surface phenomenon confined to the bare rocks of peaks and ridges1 when such rocks1 whether gabbro1 granite1 basalt1 trachyte1 or dacite1 display magnetic polarity4 ,dana1 with regard to the basaltic mountain of ,tahiti1 remarks that the compass was often rendered useless by the local attraction of the rocks1 bearings taken being found to vary two to three points on changing the position of the instrument4#adc ,major ,haig says that the compass becomes perfectly useless anywhere in the neighbourhood of one of the mountain-masses or extinct craters in ,mauritius1 and attributes this effect to the magnetite in the basalt4#add ,on the summit of ,mauna ,loa in ,hawaii1 at the edge of the great crater and in the vicinity of the site where ,commodore ,wilkes carried out his pendulum observations in #ahdj1 ,i found my compass-needle greatly affected by local attraction1 but ,i neglected to inquire further into the matter4 ,judging from my sojourn of twenty-three days on this mountain-top1 thunder-storms are of very rare occurrence there2 but the electric condition of the air is at times very evident1 and its physiological effects are somewhat distressing4 ,my blanket at night crackled in my hands and emitted sparks1 so that ,i could trace with my finger the letter ,a in phosphorescent hues on its surface4 ,that lightning is directly responsible in some instances for the magnetic polarity of rocks in mountain-peaks is also well established4 ,it has been illustrated in an indirect fashion only last year in the disaster on the ,wetterhorn4 ,rocks partially fused by thunderbolts and displaying polarity occur on the summit of the ,riffelhorn and on one of the peaks of ,monte ,rosa1 and fulgurites have been also obtained from ,mont ,blanc4444 ,it is not always easy to explain1 however1 isolated cases of polaric rocks where no signs of fusion occur4 ,whilst descending into the ,valle del ,bove from the ,etna ,observatory1 ,i picked up four small volcanic bombs of basic lava1 of which one displayed polarity1 the poles being situated at the sides of the bomb4 ,zirkel quotes the observation of ,naumann on the summit of the volcano of ,moryoshi in ,japan4 ,here out of a number of lava-blocks lying about only one exhibited marked polarity1 whilst the rest showed no signs of it4 ,before dealing with the polaric rocks of ,vanua ,levu1 ,i will refer to two localities in other parts of the group where magnetic rocks have been observed4 ,during the ,wilkes' expedition in #ahdj1ade ,lieutenant ,underwood observed great local attraction at ,naikovu1 a rock #ij feet high of volcanic formation lying off the south end of ,nairai ,island4 ,he found a 8deviation0 of #ac points 7#adi degrees7 at the top of the rock1 whilst at the foot near the water the needle gave correct bearings4 ,in the ,sailing ,directions for the ,pacific ,islands1 published in #aijj1 the 8deflection0 at the summit is said to be #hg degrees4 ,it is stated by ,mr4 ,eakle in his paper 7quoted on p4 #bic7 on the rocks collected by the recent ,agassiz expedition that this rock is composed of an augite-andesite4444 ,i have learned from ,mr4 ,alex4 ,barrack that there are some highly magnetic rocks on the west coast of ,viti ,levu in the vicinity of ,likuri ,harbour in the ,nandronga district4 ,it is said that specimens sent down to the colonies were found to contain #ie per cent4 of magnetite4 ,it is very probable that the results obtained by me for ,vanua ,levu can be generally applied to the other large islands of the group4 ,the observations were made during my various geological journeys and deal only with certain aspects of this interesting subject4 ,the first feature in this connection is the frequency with which simple magnetism is displayed by the acid as well as basic volcanic rocks of this island4 ,about #ie per cent4 of the volcanic rocks collected attract both ends of the needle4#adf ,this property of volcanic rocks is well known1 and is to be attributed to the magnetite in the groundmass4#adg ,on examining the character of the non-magnetic rocks it appears that almost all belong to two groups where magnetite might be expected to be scanty4 ,the first includes the pitchstones or basic glasses1 sometimes fresh1 at other times more or less palagonitised4 ,the second comprises the highly altered basic rocks1 where the ferro-magnesian silicates have been replaced by viridite1 calcite1 and pyrites4 ,it is not1 however1 to be implied that rocks of these two kinds will not sometimes attract the needle4 ,many do not1 and those in my collection that do so act feebly4 ,coming to the magnetic polarity displayed by some of these rocks1 when the ordinary hand-specimen behaves like a magnet in attracting one pole of the needle and repelling the other1 it is to be at first observed that a rock can become polaric without being previously magnetic4 ,dr4 ,folgheraiter has observed polarity in the case of fragments of ancient bricks and pottery2 and he has described the same effect in the masonry of a house struck by lightning4 ,in one or two of the ,vanua ,levu acid rocks showing polarity this can be also premised since magnetite is present in very slight degree4 ,polarity is very frequent among the volcanic rocks of this island4 ,out of #ebj specimens in my collection1 which was made without any reference to this matter1 #hj1 or #ae per cent4 are polaric4 ,of these seven-eighths are basic and the rest are acid rocks2 but this proportion is partly accounted for by the far greater prevalence of basic rocks in the island4 ,the basic rocks showing polarity include some of the heaviest olivine-basalts with a specific weight of #cj1 as well as some of the lighter augite-andesites with specific weight of #bg4 ,they comprise the coarse textured dolerite as well as the vitreous pitchstone and include both scoriaceous and amygdaloidal rocks4 ,the polaric acid rocks are mostly referable to the dacites1 with a specific gravity of #be to #bf4 ,humboldt remarked long ago that there is no direct relation between the degree of polarity and the specific weight4 ,this is well brought out in the table subjoined2 but it should be at once observed that there is an indirect relation4 ,although when we arrange the rocks in a series according to their specific weight we find no corresponding relation in the amounts of the polarity1 we observe that the extent to which polarity can be developed is markedly greater in basic than in acid rocks4 ,from this it may be inferred that the degree of intensity of the exciting cause required to give polaric powers of a certain value to an acid rock1 like a dacite1 would be much greater than that necessary to endow a basalt with equal powers4 ,we should not expect to find the same amount of polarity in the bare rocky peaks of two adjacent mountains1 where one was of dacite and the other of basalt2 and1 other things being equal1 if two mountains had been exposed for ages to the same conditions1 we should regard the polaric powers of the two as nature's equivalent values for the work of atmospheric electricity1 on the two rocks in question4 ,we have two such mountains in ,vanua ,levu in the case of the adjacent peaks of ,ngaingai 7#b1ddh feet7 and ,navuningumu 7#a1ica feet7 which are about #b miles apart and possess similar bare rocky pointed summits4 ,i take it that the polaric power of #be of the dacite 7sp4 gr4 #beg7 in the first case is equal to the power of #ij of the basaltic andesite 7sp4 gr4 #bhb7 in the other4 ,in the dacitic peak of ,ngaingai and in the basaltic peak of ,navuningumu we can measure what work atmospheric electricity can accomplish in the course of ages in the magnetisation of rocks4 ,the other conditions being taken as about the same1 the main determining difference is to be found in the rock-characters4 ,in the table on the opposite page we have a series of volcanic rocks placed according to their specific weights1 which range from #be to #cj1 and in the second column are shown their relative polaric powers as indicated by the number of degrees the north end of the magnetic needle is repelled by the corresponding pole in the hand-specimen4 ,for this purpose a magnetic needle #b inches in length 7strictly speaking #fe centimetres7 was employed1 a card marked in degrees being placed beneath4 ,the north pole of the stone was placed in contact with the north end of the needle1 and after the needle had become stationary in its new position a reading was taken4 ,these polaric rocks came under my notice over most of the island4 ,they are infrequent in the district between ,undu ,point and the ,wai-ni-koro ,river1 where1 however1 acid tuffs are largely exposed2 and ,i did not find them in the ,natewa ,peninsula east of ,lea1 their absence from my collections made in the ,mount ,freeland range being remarkable4 ,but it is probable that this is due to the surface conditions1 since dense wood covers the slopes1 and bare rocky peaks are rarely to be seen4 ,with regard to the influence of locality on the occurrence of polaric rocks1 the results may thus be classified4 ,about one-third are found in the exposed rocky peaks of hills and mountains4 ,another third are found where the rocks are bared in headlands1 coast cliffs1 inland-bluffs1 ridge-tops1 and in the open basaltic plains where trees are scanty4 ,on the other hand1 a third occur in situations1 as in wooded districts where the rock exposure is scanty1 when it is not easy to explain the polarity1 unless it was developed in clear districts that have since become covered with forest4 ,table showing the ,relation between the ,specific ,gravity and the ,polarity of ,volcanic ,rocks4 ---------------------------------------- ------------------------- ,character of rock4 ,specific gravity4 ,amount of polarity4#adh ---------------------------------------- ------------------------- ,dark olivine-basalt #cjj #aj ,grey #bid #bi #bib #g ,dark #bij #aj #bhg #cj ,basaltic andesite #bhb #ij #bgg #e ,pyroxene-andesite #bgb #ch ,dacite #bfa #ag #bei #e #beg #be #bej #ad ---------------------------------------- ------------------------- ,in no place did any evidence of the direct action of lightning come under my notice4 ,mr4 ,s4 ,skinner who kindly looked at a few of these rocks says that he found no trace of fulgurites in them4 ,it is probable that here as in the mountains of ,skye1 as described by ,mr4 ,harker1 these effects are the result of the general influence of atmospheric electricity independently of the direct agency of lightning4 ,the frequency of polaric rocks in the highest peaks of the island is very remarkable4 ,generally speaking1 all the bare summits of the mountains are polaric4 ,in my experience there is no exception4 ,all the rocks obtained from the actual summits show polarity4 ,the variety of rocks thus affected is suggestive2 and this chapter may be concluded with a brief reference to their mode of occurrence on some of the mountain-peaks4 ,in ,mbatini1 #c1dcg feet in height1 which is the highest mountain of ,vanua ,levu1 the pyroxene-andesite of which the bare rocky peak is composed is somewhat weathered and has a polaric or repellent power of #bh4 ,specimens of rock obtained below the top show no polarity1 the mountain being well wooded except at the summit4 ,in the adjacent mountain of ,koro-mbasanga1#adi the polaric rocks are limited to those exposed in the peak which is bared of vegetation4 ,the rocks in question are tuff-agglomerates1 the small blocks of pyroxene-andesite standing out from the tuff having a polaric force of #ad or #ae4 ,this effect has been produced in greatest intensity in the isolated peak of ,navuningumu 7#a1ica feet7 in the ,ndrandramea region4 ,here the bare summit is formed of a semi-vitreous1 slightly vesicular1 basaltic andesite with a specific gravity of #bhb in its present condition4#aej ,this rock is powerfully polaric1 and rendered the compass useless1 the deviation generally to the westward varying from #bj to #ej4 ,i place its repellent force at about #ij1 hand specimens affecting the magnetic needle at a distance of #ac or #ad inches4 ,none of the various rocks obtained from the wooded slopes below displayed polarity4 ,the neighbouring mountain of ,ngaingai is composed entirely of dacite having a specific weight of #beg4 ,the highest point of the summit1 #b1ddh feet above the sea1 is bare and rocky1 and the stone here is markedly polaric1 the repellent force being about #be4 ,specimens from the lower wooded slopes show no polarity4 ,near by rises the hill of ,ndrandramea1 which is composed in mass of acid andesites or dacitic rocks4 ,the summit 7#a1hjj feet7 is scantily vegetated1 and here the somewhat weathered rock which has a specific weight of #bdd 7probably near #be in the fresh condition7 has a polaric force of #ad4 ,specimens of a more compact rock taken from the wooded slopes #cjj feet below the summit 7sp4 gr4 #beh7 and from #gjj feet below the top 7sp4 gr4 #bfh7 showed no such effect2 but a specimen taken from a mass of agglomerate in the last locality repels the needle #ab4 ,its specific gravity is #bfa1 and no doubt the mass had been originally a portion of an exposed cliff-face4#aea ,the summit of ,mariko 7#b1hij feet71 the ,drayton ,peak of the chart1 is formed of a rubbly agglomerate of a compact basic andesite4 ,though it displays bare rock-faces1 the actual peak has a soil-cap at least #ah inches deep and supports small trees and shrubs4 ,notwithstanding this1 ,i found when standing on the peak that my compass was very noticeably affected1 the pull being to the eastward1 whilst the amount of deviation increased from #aa to #af when changing from the sitting to the standing position4 ,specimens of blocks from the agglomerate forming a rock-face #aj feet below the summit possessed polaric powers of #ab and #e4 ,others of the same rock exposed in a cliff-face #dej feet below had a weak repellent power of only #d4444 ,as in the case of ,mariko1 the top of ,thambeyu 7#b1gjj feet7 is vegetated2 and beneath the smaller trees blocks of polaric rocks lie on the surface4 ,one of these1 a pyroxene-andesite 7sp4 gr4 #bgb71 from which ,i obtained a specimen1 has a polaric power of #ch4 ,in another case1 that of an amygdaloidal rock of the same character1 the repellent power is #ad4 ,i might mention several other polaric peaks1 but it will be sufficient to refer to one or two other localities4 ,in the mountainous basaltic district around ,solevu ,bay the peaks are usually polaric4 ,specimens from the top of ,uli-i-matua1 #a1ajj feet1 have a repellent power of #ae4 ,the three-peaked hill of ,koro-tolu-tolu appears to be in the mass of polaric basalt from the foot to the summit1 having a repellent power varying from #d to #cj1 the most active specimens being obtained from the lower slopes1 which1 however1 are scantily covered with trees4 ,samples of the grey basalt from ,koro-i-rea show polaric powers of #c to #g4 ,as examples of the numerous lesser hills with bare rocky polaric summits ,i will first take ,bare-poll ,hill facing ,soni-soni ,island4 ,this hill is only about #aej feet above the sea1 its top being formed by two large masses of a basic andesite lava with a glassy groundmass1 incrusted with agglomerate1 the whole representing a volcanic 8neck40 ,a specimen of the rock masses has a repellent force of #bb4 ,another instance is afforded by ,vatui1 a hill #dej feet in height situated south of ,mount ,sesaleka4 ,its summit is capped by a naked mass of tuff-agglomerate pierced by a dyke #ah inches thick of an olivine-basalt1 with a specific gravity of #bij and a polaric power of #aj4 ,a somewhat suggestive example is afforded by the hill of ,na ,suva-suva1 #a1aaj feet high1 which overlooks ,naindi ,harbour to the east of ,savu-savu ,bay4 ,it is only occupied by trees in its upper part1 and a specimen of the olivine-basalt1 of which the hill is composed1 that was obtained from the wooded summit1 shows no polarity2 whilst another from the slopes1 two-thirds of the way up1 which had been cleared of trees1 has a repellent force of #aj4 ,the polarity of the olivine-basalt from the well-wooded slopes of ,ulu-i-ndali1 a range #a1ajj feet in height on the east side of the ,wainunu estuary1 is not so easily explained2 the intensity varies from #h to #bh4 ,ngalau-levu1 a hill #a1fej feet in height1 rising behind ,lea on the south coast of ,natewa ,bay1 is polaric in its upper portion4 ,specimens of a hemicrystalline basic andesite1 somewhat scoriaceous1 which form the agglomerate of the rocky summit1 have a repellent force of #ah1 whilst a similar rock from the agglomerate of an exposed spur two-thirds of the way up the hill has a force of as much as #ch4 ,a curious case of polarity is exhibited in a bare tuff overlooking the ,vui-na-,savu ,river between ,rauriko and ,vitina4 ,it is composed of a much weathered whitish trachytic rock1 which in appearance affords no promise of polarity1 but has the power of repelling the magnetic needle #b to #c4 99 99 99 99 99 ,note on the ,average ,polarity 7,repellent ,power7 of the ,volcanic ,rocks of ,vanua ,levu4 ,it would appear from the table given below that the difference in the average polarity of acid and basic rocks is not very great4 ,the average for rocks with a specific gravity below #bg is about #aj2 and that for heavier rocks is about #ad4 ,the difference mainly lies at the maximum end of each series1 the capacity for extreme polarity being1 as before remarked1 markedly greater in the basic rocks4 ---------------------------------------- -------------------------- ,polarity4#aeb ,specific ,character of rocks4 ,number of ------------------ gravity4 specimens4 ,range4 ,average4 ---------------------------------------- ------------------------- #bej-bei ,dacites #f #b-be #aaf #bfj-bfi ,dacites and #e #c-af #hf augite-andesites #bgj-bgi ,augite-andesites #e #e-ch #acb #bhj-bhi ,basaltic andesites and #ah #c-ij #aej olivine-basalts #bij-cjj ,olivine-basalts #ad #c-bi #abg ---------------------------------------- ------------------------- ,it is1 however1 noteworthy1 as indicated by the value of the average in each series that not one of them is a good series4 ,they form curves which in each case present an extreme maximum variant which is suggestive of quite another degree of magnetising agency4 ,this is also illustrated in the combined curve of all the results given above4 ,the acid as well as the basic series are thus characterised1 and the extreme maximum variants are in each instance afforded by the highest mountain peaks4 ,it is probable that there is an accelerating ratio of magnetisation with increased elevation4 ,however that may be1 it appears evident from my observations on the two adjacent peaks of ,ngaingai and ,navuningumu that the limits of polarity acquired through atmospheric electricity without the direct action of lightning would be1 as measured by the scale here employed1 four times as great for a dacite 7#be7 as for a basaltic andesite 7#ij74 ,,chapter ,,xxvii ,,some ,,conclusions ,,and ,,their ,,bearings ,,vanua ,,levu is a composite island built up during a long period of emergence1 that began probably in the later ,tertiary period1 by the union of a number of large and small islands of volcanic formation representing the products of submarine eruptions4 ,it differs in this respect from ,viti ,levu which is much more massive in its profile and possesses a greater proportion of plutonic rocks4 ,when1 however1 ,viti ,levu comes to be systematically examined1 it is likely that traces of its composite origin will be found4 ,the evidence seems to show that it is older than ,vanua ,levu2 but they are both situated on the same submarine platform1 the area of which is nearly equal to the combined areas of the two large islands that rise from it4 ,this platform1 as indicated in the small plan of the group1 is limited by the #ajj-;fathom line in the charts2 but since the reefs on their seaward slopes plunge down precipitously1 such a line practically serves to delineate the margin of the plateau4 ,it has been my object to show on previous pages#aec that this submarine platform is a basaltic plateau built up by submarine lava-flows and incrusted with coral reefs and their deposits4 ,it has been pointed out that this platform passes gradually1 as it proceeds landward1 into the low-lying basaltic plains that constitute the sea-border in the western part of the island1 where the breadth of the submerged plateau is greatest4 ,the basaltic flows of the plains often display the almost vertical columns of slightly inclined flows4 ,their apparent termination at the sea-border1 where they are in places covered over with submarine deposits1 cannot1 however1 be accepted as their real limits4 ,according to my view they extend several miles seaward and form the platform1 as is shown in the sections on pages #fb and #ajg4 ,illustration3 ,,fiji ,,islands4 ,,from ,,admiralty ,,chart #ghj1 ,,corrected ,,to #aija4 ,,all ,,depths ,,beyond #ajj ,,fathoms ,,are ,,coloured ,,black4 ,,heights ,,in ,,feet1 ,,depths ,,in ,,fathoms4 ,we have in the great basaltic mountain of ,seatura1 which forms the bulk of the western end of the island1 a probable source of many of these basaltic flows2 and the occurrence inland in the western half of ,vanua ,levu of elevated table-lands of basalt like that of ,wainunu1 which extend from the centre of the island to near the coast1 afford testimony that the formation of these flows extends over a considerable period of the island's history4 ,it is held by ,professor ,agassiz that these submarine platforms are the work of erosion into the flanks of the up-heaved islands4#aed ,in ,chapter ,,ii4 it has been pointed out that the eroding agencies are not actively in operation in our own day1 and that there is good reason for the belief that the process of amalgamation by which ,vanua ,levu has been built up during a prolonged period of emergence1 is not suspended at the present time4 ,it is assumed that the uniformity in ,nature's methods has not been broken4 ,if1 however1 we have here platforms of erosion1 the coasts of ,vanua ,levu1 as far as my interpretation goes1 supply no evidence of it2 and we have to imagine that a period of emergence extending over a geological age has been followed by a similarly vast period of erosion without much change in level4 ,whatever agencies have been at work1 the production of submarine platforms #aj to #bj miles in width must have been a stupendous operation2 and we shall be obliged to inquire whether plateaux1 either submarine or upheaved1 occur in association with volcanic islands in other parts of the world1 and under what conditions they have been formed4 ,at least four hypotheses have been framed with regard to the submarine platforms of ,fiji4 ,there is first the original theory of subsidence of ,darwin2 but ,vanua ,levu1 which presents one long story of emergence1 offers nothing to support this view4 ,there is the growth of a reef seaward on its own talus1 as advanced by ,murray4 ,there is the theory of erosion of ,agassiz4 ,there is lastly my own idea of basaltic plateaux incrusted by reefs4 ,we may therefore inquire as to the evidence afforded by ,vanua ,levu in favour of these views4 ,basaltic flows1 in places covered by submarine deposits1 form the low plains at its sea-border1 where the platforms are broadest2 and there rises a basaltic mountain of the ,mauna ,loa type1 occupying most of the western end of the island4 ,no one would be bold enough to place the limit of these basaltic flows at the water's edge2 and as is indicated in the sections1 they probably extend for miles under the sea4 ,if we look for an island which in its extensive palagonite-formations1 in its basaltic table-lands and later basaltic flows1 in its huge mountain-ridges1 and in its evidence of submergence1 most resembles ,vanua ,levu1 we seem to find it in ,iceland4 ,it is in ,iceland1 ,i think1 that we must expect an explanation of many of the puzzling features in the structure of ,vanua ,levu4 ,i pass on now to refer to some of the general points in the geology of this island1 which have been dealt with in detail in the earlier chapters of this work4 ,with regard first to the distribution of the volcanic rocks1 it may be remarked that my materials do not lend themselves to making a geological map4 ,the most comprehensive idea of the principal points in the geological structure will be obtained by reading the description of the profile given in ,chapter ,i4 ,there is1 however1 a method in the distribution of the rocks that may be again noticed here4 ,the plutonic rocks are very scantily exposed1 as is shown on page #bdi2 and they are not displayed at all in the western half of the island4 ,the more basic eruptive rocks1 the olivine-basalts and basaltic andesites1 are mainly confined to the western half1 that is1 west of ,nanduri on the north and of the ,ndreke-ni-wai ,river on the south4 ,ordinary augite-andesites occur also in the western half2 and together with the hypersthene-augite-andesites they are found over most of the rest of the island1 excluding the north-east portion1 east of ,lambasa and ,tawaki1 where quartz-porphyries1 oligoclase-trachytes1 and acid pumice tuffs prevail4 ,the acid andesites1 including the hornblende-andesites and the dacites or felsitic andesites1 are best represented in the ,ndrandramea district in the midst of the basic rocks4 ,they occur in the isolated peaks of ,na ,raro and ,vatu ,kaisia and in one or two other localities1 as in the ,valanga ,range and on the shores of ,natewa ,bay in the vicinity of the ,salt ,lake4 ,these peaks of acid andesites1 as in the instances of ,vatu ,kaisia and ,soloa ,levu1 are at times in part overwhelmed or surrounded by the basaltic flows4 ,this singular feature of bosses of acid rocks in the midst of basaltic fields offers another point of resemblance between ,iceland and ,vanua ,levu4 ,the mountain-types vary considerably1 the ridge-mountains1 however1 being most characteristic of the island4 ,the basaltic mountain of ,seatura1 though its lava-flows were evidently in the main submarine1 belongs as before observed to the ,mauna ,loa type4 ,in its radiating valleys and gorges and in other characters it recalls the description given by ,dana of the island of ,tahiti4 ,the peaks of acid andesites1 represented in the isolated hills and mountains of the ,ndrandramea district1 and in the solitary mountains of ,vatu ,kaisia and ,na ,raro1 are the necks and stumps of submarine volcanoes dating back to the pre-basaltic period of the island4 ,it is1 however1 in the great mountain-ridges of the central portion of the island1 those of ,va ,lili1 ,korotini1 ,nawavi1 ,thambeyu1 ,mbatini1 ,mariko1 c41 that we find1 as just remarked1 the most typical features of the internal topography of ,vanua ,levu4 ,agglomerates overlying palagonite-tuffs and clays1 that are usually foraminiferous and sometimes inclose molluscan shells1 clothe the slopes of these mountain-ridges up to elevations of #b1ejj feet and over above the sea4 ,most of these great ridges1 now more or less covered over by these submarine deposits1 represent lines of submerged vents1 of which only a few raised their summits above the sea in the earliest stages in the history of the island4 ,at this early period there were no coral reefs4 ,some of the ridges present a marked parallel arrangement1 recalling the arrangement of the mountain-ridges and lesser chains of hills as described by ,dr4 ,johnston-,lavis in the account of his visit to ,iceland4#aee ,the description of ,hekla 7as given by ,thoroddsen7 as 8an oblong ridge which has been fissured in the direction of its length and bears a row of craters along the fissure10#aef comes very near to my conception of the original condition of these great mountain-ridges before the emergence4 ,dr4 ,johnston-,lavis sees in ,hekla a type of volcanic mountain very different from that of ,vesuvius and ,etna4 ,he regards it as a ridge marked by a number of parallel ridges and furrows1 and built up along a main fissure with a number of subsidiary parallel fissures4 ,the part taken by palagonite in the composition of the finer deposits over the greater portion of ,vanua ,levu is another prominent characteristic of the island4 ,palagonite1 as ,i have suggested in ,chapter ,,xxiv41 is formed probably on the surface of submarine flows of an ophitic basaltic rock4 ,the age of the more recent of the deposits of this island1 the fossiliferous tuffs1 the pteropod-ooze rocks1 and the foraminiferous muds1 cannot be far different from that of the same deposits in other parts of the group1 since it is apparent that the same general movement of emergence has affected both of the two larger islands4 ,professor ,martin of ,leyden informed ,dr4 ,wichmann that the fossil shells found in the tuffs of ,viti ,levu1 ,ovalau1 and other islands were ,tertiary but not older than the ,miocene4#aeg ,dr4 ,dall1 after examining the fossil mollusks collected by ,professor ,agassiz from the elevated limestones of ,fiji1 confirmed the impression formed by the latter as to their late ,tertiary age4 ,none of the genera were extinct1 and the fossils were in his opinion younger than ,eocene and either ,miocene or ,pliocene4#aeh ,the ,rev4 ,j4 ,e4 ,tenison-,woods described as extinct ,tertiary fossils1 some corals and mollusks from the interior of ,ovalau4#aei ,mr4 ,h4 ,b4 ,brady1 basing his conclusions on the character of the foraminifera1 assigned a ,post-,tertiary date to the ,suva 8soapstone0 taken at elevations up to #ajj feet in that neighbourhood4#afj ,professor ,david referring to some fossil teeth of ,carcharodon and to a fossil ,tridacna found at ,walu ,bay infers that the deposits are at least as old as ,pliocene but not as old as the earlier ,tertiaries4#afa ,since1 as pointed out by ,professor ,david1 the latest movements of emergence have taken place in recent geological time1 these various observations go to show that whilst the latest exposure of deposits has occurred in recent time the mass of the fossiliferous deposits date back to the ,pliocene and the ,miocene periods4 ,according to ,wichmann these islands were in a continental condition during the ,palozoic and ,mesozoic periods1 and it was only in the later ,tertiary age that the movement of subsidence began that prepared the way for the formation of the more recent deposits4 ,the submergence during the ,tertiary period and the subsequent emergence are facts that cannot be gainsaid2 but we may ask where is the evidence of the continental condition during the earlier periods4 ,there is little in the results obtained from ,vanua ,levu that directly supports such an hypothesis4 ,under such circumstances one ought to have discovered in the deposits of this island some evidence of this early condition1 and there should be found in the fauna and flora some traces of the original organisms4 ,according to ,hedley there is some indication of a continental condition in the molluscan fauna1 and he quotes ,fairmaire as regarding the ,coleoptera as of a continental character2 but no one1 that ,i am aware of1 has found any direct evidence of the ,pre-,tertiary periods in this group4 ,it is in harmony with the geological characters to assume that these islands made their first appearance during the ,tertiary epoch4 ,coming to the subject of the movements whether of land or sea that led to the appearance of these islands1 we shall not be begging the question if we speak of their 8emergence40 ,there is no doubt as to there having been during and since the ,tertiary epoch an emergence of some thousands of feet1 allowing for the original depth of the foraminiferous deposits now found at elevations of over #b1jjj feet above the sea4 ,in ,chapter ,,ii4 it is shown that there is good ground for the belief that these changes of level have not altogether ceased4 ,of what nature1 we may ask1 is this movement4 ,we have before us the grand conception of ,suess that the emergence of the land in the different phases of geological time has been produced by the general lowering of the level of the ocean arising from local subsidences of the earth's crust4 ,this view in the case of the recent calcareous formations of the ,pacific is applied to the terraces of the ,loyalty ,islands2#afb and it follows that it is also applicable to the elevated calcareous deposits of the islands of the ,western ,pacific as a whole1 as in the case of the ,tongan ,islands1 the ,new ,hebrides1 the ,solomon ,group1 c4 ,such a general change of level ought to be represented in the large island of ,hawaii in the ,north ,pacific1 since it could not be confined to one locality in this ocean4 ,there is no evidence of emergence1 as far as ,i know1 presented by this island4 ,during my sojourn there1 ,i examined much of its coasts4 ,now the antiquity of the flora of this group is sufficiently attested by the circumstance that it ranks first among the oceanic groups of the ,pacific for the number of endemic plants that it possesses2 and the same conclusions may be drawn from the insects and the birds4 ,there is no evidence in this group1 one of the most ancient of the ,pacific archipelagoes1 of that great movement of emergence1 which is abundantly demonstrated over the ,western ,pacific4 ,the standpoint is therefore taken that the movement of emergence which began in the ,tertiary period and is probably still in operation is confined to the southern portion of the tropical ,pacific4 ,speaking of the time of the ,fijian emergence1 ,professor ,agassiz observes that 8it is not unnatural to assume that it was coincident with the elevation of ,northern ,queensland1 and that the area of elevation included ,new ,guinea1 the islands to the east of it as far as ,new ,caledonia1 and as far east as the most distant of the ,paumotus1 and extended northward of that line to include the ,gilbert1 ,ellice1 ,marshall1 and ,caroline ,islands40#afc ,from the report of ,mr4 ,andrews#afd it is evident that in the ,lau ,islands of the ,fiji ,group volcanic outbreaks have taken place since the last upheaval4 ,he describes in the case of ,mango and other islands the manner in which cliffs of limestone form inliers in flows of andesitic lava4 ,in the history of these islands he first distinguishes the period of calcareous deposits1 when the bedded limestones forming the submarine plateau were laid down4 ,then followed a period of volcanism during which masses of volcanic materials were erupted along the axis of elevation4 ,alternating epochs of upheaval and stable equilibrium ensued1 during the last of which the reefs grew outwards and formed the terraces now so characteristic of the profiles of the islands4 ,after the last upheaval the volcanic forces became again active4 ,there is much of special interest in the account given by ,mr4 ,andrews of the ,lau ,group4 ,the blocks of limestone included in the volcanic agglomerates distinguish the ,lau detrital rocks from those of ,vanua ,levu4 ,there is no evidence that coral reefs existed during the early stages of the emergence of ,vanua ,levu to be obtained from the submarine formations found on the higher levels1 #a1jjj to #b1ejj feet above the sea4 ,the period of emergence for this island may be divided into an earlier and into a later stage1 the last corresponding to the age of emergence of the ,lau ,islands4 ,the earlier stage1 which may be termed the 8,pre-,lau0 stage1 is represented by the deposits of the higher slopes of ,vanua ,levu1 that is above #a1jjj or #a1bjj feet4 ,this is really the critical epoch in the history of this group1 and assuming that the movement of emergence has been fairly uniform over the archipelago we cannot but be astonished at the absence of all traces of ancient reefs in the earlier stage4 ,we may infer from the observations of ,mr4 ,lister#afe that the islands of the ,tonga ,group represent the ,lau stage of the emergence4 ,they are similar in height and in general geological structure to the islands of ,lau1 that of ,eua1 for instance1 which has an elevation of #a1ajj feet1 being formed of reef-limestones overlying volcanic tuffs4 ,dykes penetrate the tuffs but do not enter the incrusting calcareous strata4 ,mr4 ,harker1#aff after examining the collections of ,mr4 ,lister1 remarks that all the rocks excepting those from ,falcon ,island appear to be of submarine formation4 ,the volcanic material1 he adds1 seems to have been almost exclusively of fragmental character4 ,it would be rash1 it is remarked1 to refer all the rocks to a ,recent age1 and some of them may be found to go back far into ,tertiary times4 ,my division of the long period occupied by the emergence of the ,fiji ,islands into two stages1 the ,lau stage corresponding to elevations of less than #a1jjj or #a1bjj feet1 and the ,pre-,lau stage which includes the earlier evidence of emergence found at heights exceeding these elevations and ranging up to #b1jjj or #c1jjj feet1 may perhaps be applicable to other regions of emergence4 ,as bearing on the question of the isolation and antiquity of the ,pacific ,islands the following approximate results for the ,hawaiian1 ,fijian1 and ,tongan floras may be here quoted4#afg ,these data are liable to correction2 but they are near enough to the truth to be very suggestive4 ,of peculiar genera of flowering plants and ferns the ,hawaiian ,islands possess about #dj1 the ,fiji ,group about #af1 and the ,tongan ,islands none4 ,of endemic species of flowering plants there are about #hj per cent4 in ,hawaii1 about #ej per cent4 in ,fiji1 and #c or #d per cent4 in ,tonga4 ,granting that there is much to be done yet in the investigation of these floras1 it would be underrating the brilliant results of the labours of ,hillebrand and ,seemann to characterise their work as sampling4 ,let us suppose1 however1 that the floras of ,hawaii1 ,fiji1 and ,tonga have been only sampled1 the data above given would be still reliable4 ,it is quite possible to obtain a botanical equivalent corresponding to the geological estimates of the relative ages of these islands2 and taking the proportion of endemic plants as our guide1 the ,lau stage1 as represented by the ,tongan ,islands1 would have a value of #c or #d1 the ,pre-,lau stage now exhibited in the earliest stage of emergence of ,vanua ,levu would have a value of #ej1 and the ,hawaiian stage older than all would have a value of #hj4 ,these results are intended as suggestive and ,i hope to work out this subject in the second volume4 ,they make the problem of the relative antiquity of these islands more mysterious than it even appeared before4 ,with regard to the vexed question of the light thrown on the past condition of these islands by the present state of their floras and faunas1 it may be at once observed that my belief in the general principle that islands have always been islands has not been shaken by the results of the examination of the geological structure of ,vanua ,levu4 ,in a correspondence in ,nature about fifteen years ago it was suggested by me that this is the position we ought to take with regard to the stocking with plants of the islands of the ,southern ,ocean1 such as ,kerguelen2 and ,i take the same standpoint for the islands of the ,pacific4 ,if the distribution of a particular group of plants or animals does not seem to accord with the present arrangement of the land1 it is by far the safest plan1 even after exhausting all likely modes of explanation1 not to invoke the intervention of geographical changes4 ,new possibilities of inter-communication1 new ways of looking at old facts1 and new discoveries of an unexpected nature come monthly before us in the progress of scientific research2 and ,i scarcely think that our knowledge of any one group of organisms is ever sufficiently precise to justify a recourse to hypothetical alterations in the present relations of land and sea4 ,the hypothesis of a ,pacific continent1#afh whether it takes a trans-oceanic form1 as advocated by ,von ,ihering1 ,hutton1 ,baur and others1 or whether it is represented by an island-continent isolated in mesozoic times1 as suggested by ,pilsbry1 receives no support from the geological characters of ,vanua ,levu4 ,nor can ,i accept as regards ,fiji ,mr4 ,hedley's theory of the ,melanesian ,plateau4 ,there is no evidence that the various islands of the ,fiji ,group were ever amalgamated and no indication of a geological nature that they were ever joined to the ,solomon ,group4 ,the ,fijis1 as we see them1 have had an independent history1 and the process at work is not one of disruption but of amalgamation1 lesser islands being united to larger islands during the prolonged period of emergence4 ,mr4 ,hedley1 however1 has some weighty data on his side more especially zoological2 but even here it would be wise to suspend one's judgment4 ,though the great mass of botanical evidence is as respects ,fiji opposed to such connections1 the distribution of ,dammara may1 however1 be fairly claimed on their behalf4 ,the dilemma into which such discussions lead us is aptly stated by ,dr4 ,pilsbry4 ,if we do not accept the hypothesis of a ,pacific continent1 we have to explain the cessation of the means of transportal in later geological times1 since this is implied in the isolation necessary for the development of peculiar characters in a fauna or a flora4 ,this was the dilemma that presented itself to me in studying the origin of the ,fijian plants4 ,assuming on geological grounds that the insular condition had been always maintained ,i had to explain the differentiation in the inland plants1 or in other words to account for the failure of the means of transportal that once existed4 ,since this subject bears directly on the past condition of the ,fiji ,islands1 ,i may be pardoned for referring to it here4 ,it belongs properly to the second volume which it is proposed to devote to the dispersal and distribution of ,pacific plants2 but as ,i contest the pre-existence of a ,pacific continent1 it is fitting though not necessary that this difficulty should be faced at once4 ,if we in imagination combine in a typical island the characters of the flora presented by islands of different elevation in the ,pacific we get a result of this kind in an island of the height of ,hawaii1 nearly #ad1jjj feet4 ,the littoral plants of such an island are found all over the coasts of the tropical ,pacific1 and for the explanation of this fact we look mainly to the agency of the ocean-currents4 ,the plants of the mountain summit1 belonging to the temperate genera of ,geranium1 ,rubus1 ,ranunculus1 ,vaccinium1 c41 are represented at least generically on the tops of the lofty ranges of the ,pacific coasts and in the interior of the continents2 and we find the explanation of the wide diffusion of such plants in the agency of the migrant birds that at no distant time1 if not actually in our own time1 were regular visitors to these mountain regions4 ,the plants of the marsh1 of the stream1 and of the pond1 belong often to species that occur in similar stations over a great portion of the world1 such as species of ,drosera1 ,ruppia1 ,potamogeton1 c42 and here the agency of wild duck and other waterfowl may be observed in active operation4 ,but when in such an island we regard the intermediate region between the uplands and the coast1 usually the forest-zone1 we find an area of change not only for the plants but also for the birds4 ,it is here that the new genera of plants have been developed that distinguish the floras of the ,pacific groups each from the others2 and here also the migrant bird1 having from some cause changed its ways1 has given rise to new varieties and to new species4 ,it is with this loss of the migratory powers of the birds of the forest-zone that ,i connect many of the important differences between the forest-floras of the different groups of the ,pacific4 ,at one time1 it would seem1 birds were far more active agents in dispersing seeds and fruits over these archipelagoes than they are at present2 but it is not held that this is concerned with the extermination and extinction of the birds of these islands in the present day4 ,the change dates far back and is far-reaching in its effects4 ,it is assumed in this argument that the alpine plant and the plant of the pond and of the sea-shore preserve their characters by reason of the means of free dispersal that they still enjoy2 and it is inferred that the plant of the forest-zone has varied more because opportunities of transportal of its kind no longer are afforded4 ,many a line of ancient migration is now broken4 ,it is suggested that in the past when birds were more generalised in type they were much more migratory in habits and that limitation of range has been associated with specialisation4 ,the plants dispersed by the birds have undergone a parallel series of changes4 ,at first widely distributed1 as in the more generalised types of birds1 they became localised in proportion as the birds to which they owed their means of dispersal lost their migratory ways2 and both plant and bird began to vary4 ,there is1 ,i am convinced1 a profound connection between birds and plants1 of which we now perceive only the last of a long series of changes4 ,this subject will be dealt with at length in the volume on plant-dispersal2 and it is only referred to here to illustrate my contention that we have yet much to learn before it would be safe to look to hypothetical changes of sea and land to explain difficulties in distribution4 ,,appendix ,note on the ,stone-,axes4--,two of these polished stone-axes from a collection made in ,vanua ,levu were selected for sections4 ,one is light-green and smooth4 ,the other has a very different appearance1 being blackish and rather rough1 its smooth surface having been apparently lost by lying in a stream-course or in wet ground for a long period4 ,both1 however1 are made of the same type of basaltic rock1 the specific gravity in one case being #bic1 in the other #big4 ,it is an aphanitic basalt with scanty olivine containing little or no residual glass and referred to genus #dj of the olivine-basalts4 ,it is by no means a common type of basalt in ,vanua ,levu1 and ,i cannot refer it to any particular locality on account of the peculiarities it presents when contrasted with rocks of the same genus4 ,the olivine is very scanty and small1 and in one of the specimens is represented only by pseudomorphs4 ,the felspar-lathes vary usually from #je to #b mm4 in length1 and the augite granules which are very abundant are #ja or #jb mm4 in diameter4 ,there is an occasional small phenocryst of augite4 ,the rock shows little or no alteration and cannot be characterised as a greenstone4 ,the greenish hue of one axe is due to weathering2 but its extension into the internal black portion of the tool is not appreciable4 99 99 99 99 99 ,note on the ascent of the tide up the ,ndreketi ,river4--,on ,july #bjth and #bast1 #ahii1 by observing the surface density it was ascertained that at high-water the sea-water reached ,navundi a mile or two below ,mbatiri4 ,at low-tide it reached about half-way between ,kanathangi and ,navundi4 ,the moon was in her quarters4 99 99 99 99 99 ,note on the 8talasinga0 districts4--,this subject will be discussed in the second volume4 ,,index ,,note4--,it has been deemed best to follow the example of the ,admiralty surveys in the spelling of native names4 ,in this book1 therefore-- ,mb the ,fijian ,b ,th the ,fijian ,c ,,nd the ,fijian ,d ,,ng the ,fijian ,g and ,q ,abbreviations1 for rock descriptions1 #bcf ,acicastello1 ,sicily1 basalt and palagonite1 #cdg ,acid and basic rocks1 regions of1 #bai1 #cgd ,agassiz1 ,prof4 ,a41 #bid1 #cgc1 #cgf1 #cgg ,agates1 #ach1 #aci1 #bbg1 #cec1 #ced ,agglomerates2 see ,volcanic agglomerates ,alg in hot springs1 #bd1 #be1 #cc1 #ch ,alps1 magnetic rocks of the1 #cfb1 #cfc ,altered rocks2 see ,propylites1 etc4 ,andesites1 acid1 #ih-ajh1 #aab1 #abc-abg1 #aic1 #aid2 relative frequency of1 #bce2 classification of1 #bic-cjf2 distribution of1 #cgd2 peaks in basaltic flows1 #ajd1 #aae1 #aaf1 #cgd2 altered1 #aje1 #big2 columnar1 #ajb1 #ajd2 pre-basaltic1 #cge ,andrews1 ,mr4 ,e4 ,c41 #g1 #bb1 #bid1 #cej1 #cgh ,artesian reservoirs1 #ci ,augite1 crystals of1 in tuffs1 #de1 #ahb1 #aic ,augite-andesites1 #ea1 #afb1 #aii1 #bjd1 #bji1 #bcb1 #bce1 #bid1 etc42 classification of1 #bci1 #bde1 #bdf1 #bff-bhd2 distribution of1 #cgd2 aphanitic1 #aag-abj1 #abe1 #afb1 #afh1 #bgi2 relative frequency of1 #bce2 see ,basaltic andesites ,avuka1 range1 #agi ,axes1 stone1 structure of1 #chc ,bare-poll1 peak1 near ,soni-soni1 #ic ,barrack1 ,mr4 ,a4 ,h41 #bg1 #abc ,barrack1 ,mr4 ,alex41 #cfd ,barratt1 ,mr41 #fh ,barrier-reef1 great1 of ,fiji2 see under ,submarine plateau #afi;,basaltic andesites1 #dg1 #ef1 #fd1 #ge1 #ajh1 #abc1 #acg1 #adg1 #adh1 #afj1 #afd1 #aij1 #bjd1 #bjf1 #bjh1 #bhh2 classification of1 #bci1 #bff1 #bgh2 distribution of1 #cgd ,basaltic rocks1 extensive disintegration of1 #eg1 #fd1 #gb1 #abi ,basaltic flows surrounding hills of acid andesite1 #ajd1 #aae1 #aaf1 #cgd ,basaltic plains and plateaux1 #f1 #ee1 #fb1 #hb1 #ajg1 #abh-ace1 #cgc ,basaltic submarine flows1 #cch1 #cdb1 #cdd1 #cdf1 #cdg1 #cgb1 #cge2 see under ,submarine plateau and ,basaltic plains ,basalts1 columnar1 #c1 #fc1 #gh1 #hc1 #hd1 #he1 #abc1 #abi1 #acc1 #adg1 #agj1 #agc1 #bjc1 #bfj1 #bhd ,basalts1 ophitic1 #ej1 #gd1 #aad1 #acc1 #acg1 #ach1 #aee1 #aei1 #afb1 #aia1 #bjd1 #bac1 #beb1 #bef1 #cdg2 the ophitic habit1 #bcg1 #bch2 ophitic sub-orders1 #bcf1 #bda-bde2 ophitic genera1 #bef1 #bfb1 #bgb-bgf1 #bhc ,basalts1 olivine1 relation of black and grey1 #hi1 #ij2 classification of1 #bci1 #bda-bdd1 #beb-bfe2 relative frequency of1 #bce2 distribution of1 #cgd ,basalts1 grey olivine1 #fe-fg1 #gc-ge1 #gg1 #hi1 #bec-bee1 #beg1 #bfa1 #bfc ,basalts1 highly basic1 #beh ,basalts1 of ,acicastello1 #cdg2 of ,mbua and ,ndama plains1 #eh1 #acd1 #bfb1 #bgh2 of ,ndreketi plains1 #acc1 #acd2 of ,sarawanga plains1 #abi1 #acd1 #bfb2 of ,savu-savu peninsula1 #aij1 #bhh2 of ,seatura1 #fc-gb1 #he2 of ,solevu ,bay1 #ge-gg2 of ,wainunu1 #he2 of ,ulu-i-ndali1 #hi ,basalts associated with palagonite1 #cdg ,basic glass1 #cab1 #cch2 see ,pitchstone1 ,crush-tuffs1 ,hyalomelan-tuffs ,bastite1 #ahb1 #big ,baur1 ,mr41 #chj ,blyth1 ,mr41 #abc ,brady1 ,mr4 ,h4 ,b41 #cbb1 #cgf ,breccias2 see ,volcanic agglomerates ,bronzite1 #ahb ,bromlow1 ,dr41 #bi ,bchner1 ,dr4 ,max1 #bb ,bulling1 ,mr41 #cb1 #cf1 #bcb ,bunsen1 on palagonite1 #cdc1 #cdd ,carbonate of iron1 concretions of1 #bbg1 #cea1 #cef ,carcharodon1 #cgf ,chalcedony1 #ac1 #ach1 #afb1 #ahc1 #aii1 #bbf-bb1 #cej-cee2 see ,agate1 ,onyx1 ,flints ,chalmers1 ,mr41 #bcc ,charts1 old and new compared1 #ah1 #ai ,chert1 #cee ,classification of volcanic rocks1 #bce ,coleoptera of ,fiji1 #cgg ,columnar structure2 see ,basalt1 ,acid andesite1 ,dacite1 ,oligoclase-trachyte ,combe1 ,commander1 #ae ,cooper1 ,mr4 ,h4 ,s41 #bi ,coral reefs1 upheaved1 #g-ab1 #ahi1 #bjj1 #bja1 #cah2 their absence in the higher levels1 #g1 #h1 #ab1 #ai1 #cge ,craters1 traces of1 #dd1 #eb1 #fg1 #hj1 #aff1 #ahf1 #aib1 #aie1 #bjb ,crush-tuffs1 #ee1 #id1 #adi1 #aeg1 #cda2 general description1 #ccd2 see below ,crushing of basic glass2 in veins1 #cdj1 #cda2 on surface of a submarine flow1 #ic1 #cch2 in matrix of pitchstone-agglomerate and in rubbly pitchstone1 #id1 #adb1 #ade1 #aeg1 #cac2 its connection with palagonite1 #ic1 #cci1 #cdj-cdb1 #cdf ,cumming1 ,miss ,gordon1 #bb1 #be1 #bi ,dacites1 #c1 #e1 #ajj1 #ajh1 #bce1 #bid1 #cjd2 columnar1 #aja1 #ajb2 definition of the term1 #bie2 classification and characters1 #bdj1 #cjb2 see ,acid andesites ,dall1 ,dr41 #cgf ,dana1 ,prof41 #c1 #aj1 #aa1 #af1 #ba1 #bf1 #gb1 #hd1 #abi1 #ace1 #bah1 #cji1 #cfc ,darwin1 ,mr41 on barrier-reefs1 #cgc ,datum-mark1 #aie ,david1 ,prof41 #cgf ,deep-sea deposits1 #ccg ,delanasau1 #fh ,dillon's ,rock1 #de ,diorite1 #ahb1 #aic1 #bce1 #bdi1 #bea ,doelter1 on hornblende paramorphism1 #cjh ,doleritic1 use and definition of the term1 #bcf1 #bch1 #bei1 #bgd ,dolomite1 #g ,drayton1 peak2 see ,mariko ,dykes1 #ea1 #ed1 #fc1 #fh-gb1 #gh1 #ha1 #adb1 #add1 #adh1 #aee1 #aef1 #afc1 #afd1 #agj1 #aga1 #ahd1 #aii1 #bjb1 #bji1 #baf1 #bbj1 #bcc1 #bcd1 #bfg1 #bfh1 #bgj1 #bgg1 #bhj1 #bhb2 their two sets of felspar-lathes1 #bch ,eakle1 ,mr41 #bic1 #bid ,earthquakes1 #cg ,emergence of ,vanua ,levu1 #a1 #g-bj1 #cba1 #cgf-cgi2 age of1 #cgf ,etna1 mount1 coast springs of1 #ci2 dykes in ,valle del ,bove1 #bcg2 magnetic bomb1 #cfd ,fairmaire1 ,m41 #cgg ,faro1 island1 ,solomon ,group1 #b ,fawn1 harbour1 #i1 #bjj1 #cah ,felsitic andesites1 #ajf1 #ajh1 #bie1 #cjj2 see ,acid andesites and ,dacites ,felsitic groundmass1 as employed in classification1 #bcf1 #bci1 #bdj1 #bdi ,felsitic orders1 #bdi1 #bia1 #big1 #cjj1 #cjb ,felspar-lathes in classification1 #bcf1 #bda ,fern1 tree1 silicified caudex of1 #cfj ,fish-scales1 fossil1 #aed ,flints1 #ac1 #ha1 #hc1 #ach1 #aci1 #bbb1 #bbf1 #cej-cfj ,floating islands1 #bbe ,floras of ,fiji1 ,hawaii1 and ,tonga1 #cgi ,flow-arrangement in classification1 #bcf-bch ,folgheraiter1 ,dr41 #cfb1 #cfe ,foraminiferal limestones1 #acj-acb1 #bjb1 #cah ,foraminiferous deposits 7tuffs1 muds1 clays71 #if1 #aji1 #acj1 #acd1 #acf1 #aci1 #adi1 #aed1 #afa1 #agj1 #aih1 #bje2 description of1 #cba-ccc2 altered1 #cbd-cbf2 thickness of1 #aef2 see ,globigerina deposits and ,palagonite-tuffs ,fossilised trees1 #bcc ,freeland1 ,mount1 #b1 #f1 #bjc-bjf1 #bfi1 #bgd ,gabbros1 #ahj1 #ahb1 #ahd1 #baa1 #bce2 classification of1 #bci1 #bdj2 characters1 #bdi1 #bej2 see ,plutonic rocks ,geikie1 ,sir ,a41 #cge ,giant sedge2 see ,scirpodendron ,globigerina deposits1 #aj1 #ee1 #aca1 #aeh1 #agg1 #ahg1 #ahi1 #aij1 #bba1 #cba-cbf1 #cdd2 see ,foraminiferous deposits ,globigerina limestone1 #cai ,gold1 alluvial1 in ,vanua ,levu1 #aaf ,granular pyroxene1 the sub-orders characterised by1 #bcf1 #bda1 c4 ,greenstones2 see ,propylites ,groundmass1 characters of1 used in classification1 #bcf-bch ,haig1 ,major1 on magnetic rocks1 #cfc ,hale ,peak1 #baj1 #bab ,hanusz1 on floating islands1 #bbf ,harker1 ,mr41 #cfb1 #cfg1 #cgi ,harman's ,point1 #aia ,hawaii1 #b1 #ch1 #he1 #cfc2 flora of1 #cgi2 coast springs of1 #ch ,hedley1 ,mr41 #cgf1 #chj ,hekla1 ,mount1 #cge ,holmes1 ,mr41 #fh ,hornblende1 magmatic paramorphism of1 #bic1 #bii1 #cja1 #cjc2 process described1 #cjf ,hornblende-andesites1 #ia1 #ahd1 #aic1 #aid1 #bja1 #bce1 #bid2 see ,acid andesites and hornblende-hypersthene andesites ,hornblende-gabbro1 #ahd1 #bdi1 #bej ,hornblende-hypersthene-andesites1 #bdj1 #bih-cjb ,horne1 ,mr41 #aj1 #ba1 #bb1 #be1 #cd1 #ee1 #ada1 #adc1 #aid1 #aie1 #bjc1 #bbe2 see the preface ,hornstone1 #cej ,hot springs1 general description of1 #ba-db2 list of1 #dj2 analysis1 #bh2 distribution in ,vanua ,levu1 #cf1 #ach1 #bcc ,humboldt1 ,a4 von1 on magnetic rocks1 #cfa1 #cfe ,hussak1 on magmatic paramorphism1 #cjh ,hutton1 #chj ,hyalomelan tuffs1 #dg1 #hj1 #aaj1 #ccc1 #ccd ,hydrothermal metamorphism2 see ,solfataric ,hypersthene2 see ,pyroxene1 rhombic ,hypersthene-andesites1 #bid1 #bif ,hypersthene-augite-andesites1 #e1 #eb #adg1 #afa1 #afd1 #afh1 #aga1 #agc-age1 #agh1 #agi1 #ahb1 #ahf1 #aij1 #aii1 #bja1 #bjc1 #bjh1 #baa1 #bcj2 classification1 #bdj1 #bdg1 #bdh2 characters of the orders and sub-orders1 #bhe-bib2 relative frequency1 #bce2 distribution1 #cgd ,iceland1 ,vanua ,levu compared to1 #cgd1 #cge ,iddings1 ,mr41 #cjf ,iron ore2 see ,limonite ,iron sand1 magnetic1 #hc1 #ajf1 #ceg ,ironstone gravel1 #cef ,islands1 permanence of1 #chj1 #cha ,jackson1 ,dr4 ,c4 ,t41 #bh ,jasper1 #ac1 #aba1 #aci1 #aii1 #cej1 #cea1 #cee ,johnston-,lavis1 ,dr41 #cdg1 #cge ,kalakala1 ,mount1 #ajc1 #cje ,kalikoso ,district1 #aj1 #ae1 #bbd-bbh1 #cej1 #cef1 #ceh ,kandavu1 #bic1 #cjf2 hot springs of1 #bb ,kavula1 #fe1 #ff ,kia ,island1 #b ,kioa ,island1 #b ,kiombo ,coast1 #ib ,kleinschmidt1 #bb1 #be1 #bic1 #cej ,koro1 significance as a prefix2 see ,place-,names ,koro-i-rea ,hill1 #ge1 #gg ,korolevu ,hill1 #de2 natural section near1 #dh ,korolevu ,river1 #fb1 #fd ,koroma1 ,mount1 #c1 #ea1 #bhe ,koro-mbasanga ,mountain1 #aff-afi1 #bhi2 name wrongly applied in ,admiralty charts1 #e1 #agb ,koro-navuta1 #ace ,koro-ni-valu2 see under ,towns ,koro-ni-yalewa ,mountain1 #aag ,koro-tambu ,mountain1 #afg1 #aga ,korotasere1 #bjh ,korotini ,bluff1 #aef ,korotini ,range or ,tableland1 #e1 #aec-afe1 #afg1 #cbe ,koro-utari1 #afc ,koro-wiri1 #aci ,kumbulau ,peninsula1 #ij-ie ,kuru-kuru ,district1 #bbh ,lambasa coast1 #bah ,lambasa ,plains1 #ach1 #cea ,lambasa ,river1 #ae1 #ach ,landslips1 effects of1 #aaa1 #agh1 #cbg ,langa-langa ,river1 #bbj1 #bbe ,lango-lango ,river1 #abb ,lau ,group1 #g1 #bid1 #cgh ,lava-flows1 indications of sub-aerial1 #eb1 #ga1 #aai1 #acc1 #aeb1 #ahg1 #aij1 #bac1 #bcb ,lea ,district1 #aii ,lekumbi ,point1 #ab1 #ai1 #fj ,lekutu ,district1 coast of1 #aa1 #ej1 #bgc2 plains1 #abh1 #cea1 #cec1 #cef2 promontory1 #af1 #ah2 river1 #ah1 #fb1 #fe ,limestones1 recrystallisation of1 #aca2 coral1 #cah2 see ,foraminiferal limestones ,limonite1 deposits of1 #ef1 #acb1 #ach1 #bbf1 #bbh1 #cea1 #ceb1 #cef1 #cei ,lister1 ,mr41 #cgh ,liversidge1 ,prof41 #bi ,liwa-liwa1 #aai ,loma-loma ,ridge1 #ada ,lovo ,valley1 #afi-agc ,lovutu1 #aef ,macdonald1 ,dr41 #ba ,magma lakelets1 #dg1 #ga1 #ib1 #bgc1 #bgf1 #bgg2 description of1 #cci-cdb1 #cdf1 #cdg ,magmatic paramorphism2 see ,hornblende ,magnetic iron sand1 #hc1 #ajf1 #ceg ,magnetic peaks and rocks1 #gg1 #ajh1 #agd1 #ahf1 #cfa-cga ,mako-mako ,hill1 #ajc ,mali ,island1 #b1 #bah ,mali ,point1 #bah ,malolo ,island1 #bid ,mangrove belt1 bare tracts in1 #aa1 #ad2 relation to reef-flat1 #ac2 rate of growth1 #ae1 #ai ,mangrove islands1 growth of1 #af1 #ag ,mariko1 range and peak of1 #e1 #agc1 #ahe-ahi1 #bhi1 #cfh ,martin1 ,prof41 of ,leyden1 #cgf ,masusu ,district1 #hd ,mauna ,kea1 #b ,mauna ,loa1 #b1 #c1 #cfc ,mauritius1 magnetic rocks of1 #cfc ,mbale-mbale ,district1 #adc1 #cac2 river1 #aej ,mbatini ,mountain1 #e1 #aff1 #agb-agd1 #cfg ,mbati-ni-kama1 hot springs of1 #cc ,mbatiri1 #acd1 #cbd ,mbenutha ,cliffs1 #aji-aaa1 #cbc ,mbona-lailai ,mountain1 #aja ,mbua ,district1 #c1 #cf1 #cg1 #dg2 bay1 #ah2 coast1 #ab ,mbua and ,ndama ,plains1 #ee-eh1 #cef ,mbua-,lekutu ,divide1 #ee1 #big ,mbua shell-bed1 #ab1 #eh ,mbuthai-sau ,valley1 #bah1 #bai ,mbutu-mbutu ,river1 #gi1 #bgi ,middle ,point1 #acg ,mountain ridges and their structure2 see under ,ridge-mountains ,mountain-towns2 see ,towns ,muanaira1 #aih ,mumu ,peak1 #ajh-aaj ,murray1 ,sir ,j41 #ccg1 #cgc ,naikovu ,rock1 #cfd ,nailotha ,mountain1 #f1 #bad-baf1 #caj ,naindi ,bay1 #h1 #ahi1 #aia1 #aie1 #cah ,naindi ,gap1 #ahi1 #aib ,naithekoro1 #aij ,naithombothombo1 point1 #ed2 range1 #bbi ,naivaka1 #b1 #c1 #aa1 #ah1 #dc-de1 #bfa ,na-kalou1 #acc ,na ,kama1 ,savu-savu1 #be2 ,lambasa1 #cb ,nakambuta ,district1 #adh-aej ,nakarambo1 #bjh ,na ,kula1 valley1 #ahd2 range1 #bcj ,nambuna ,district1 #ajf ,nambuni ,spur1 #add ,nambuonu1 hot springs1 #cb ,nandi ,bay1 #gh ,nandi ,gorge1 #fi1 #gh1 #bgh ,nandongo1 island1 #af1 #ag2 town1 #baf2 hot springs1 #cc ,nandronandranu district1 #aag-aba ,nandroro ,district1 #ff ,nandua ,district1 #hf1 #cbj1 #cdd ,nanduri ,district1 #aa1 #ad1 #ace1 #acf ,nangara-ravi ,cave1 #ada ,nangara-vutu1 #bje ,nangorongoro ,peak2 see ,ngaingai ,na ,raro ,gap1 #abg ,na ,raro ,mountain1 #b1 #e1 #abc-abg1 #bif1 #cja1 #cje ,narawai ,district1 #ff ,nareilangi1 #abd ,narengali ,district1 #adj1 #adg1 #adi ,narikosa ,point1 #bbj ,na ,salia1 #aea ,na ,savu1 tableland1 #gi-ha2 falls1 #gi1 #bgi ,na ,seyanga1 #ajh ,na ,sinu1 #adf ,na ,suva ,range1 #fd ,na ,suva-suva ,hill1 #aib1 #cfi ,natasa ,bay1 #bji ,natewa ,bay1 north-coast1 #i1 #bjh1 #bji1 #bia ,natewa ,peninsula1 #f1 #i1 #aig-bjf ,nativi1 #ej ,natoarau1 hot springs1 #bc2 river1 #aeh ,na ,tokalau1 #ia ,natoto ,hill1 #bbi ,natua ,district1 #acd1 #adi1 #cbc ,natuvo or ,natuvu1 hot springs1 #cc1 #bji ,naumann on polaric lavas1 #cfd ,navakaravi ,hot ,springs1 #cd ,navakavura1 #if ,na ,vatu ,islet1 #id ,navetau1 #bje ,naviavia ,islet1 #h ,navingiri1 #df ,navuni1 #bjb2 hot springs1 #ce ,navuningumu1 #ajh-aab1 #cjc1 #cfh ,nawavi1 range1 #ace2 hot springs near1 #ca ,nawi or ,na ,wi1 island1 #bf1 #aib2 hamlet1 #baa ,ndaku-ndaku1 bay1 #bjh2 hot springs1 #cd ,ndama1 river and valley1 #fb1 #fg1 #fh1 #ga2 plains1 #ee-eh ,ndavutu1 district and river1 #hg2 for hot springs2 see ,wainunu ,ndawathumi1 #fd1 #hj ,ndevo district1 #bje2 hot springs1 #ce ,ndoendamu ,mountain1 #bji1 #bab ,ndrandramea1 district1 #b1 #c1 #hc1 #bif2 map1 #ii2 description1 #ih-aab ,ndrandramea ,mount1 #ajb1 #bif1 #cjj1 #cjd1 #cfh ,ndranimako1 #if1 #cbb1 #cea ,ndrawa1 district1 #abj1 #bha2 river1 #aah1 #abj ,ndreke-ni-wai1 ,natewa ,bay1 #bjj1 #bjc2 hot springs1 #cd ,ndreke-ni-wai1 ,savu-savu ,bay1 #aej1 #aeb ,ndreketi1 river1 #ae1 #abh1 #acb1 #chc2 plains1 #acb1 #bgc1 #cea ,ndriti ,basin1 #fg-gb1 #bfh1 #bgj1 #bhb ,ndrukau ,mountain1 #bac ,new ,hebrides1 #a ,ngaingai ,mountain1 #ajj1 #bif1 #cjb1 #cjd1 #cfh ,ngala ,mountain2 see ,freeland ,ngalau-levu ,range1 #f1 #aii1 #bjj1 #cgj ,ngangaturuturu ,cliffs1 #aai ,ngau ,island1 hot springs of1 #bb ,ngawa ,river1 #ach ,ngelemumu1 #ahj1 #bai ,ngone ,hill1 #ahc ,nukumbolo1 district1 #aea1 #afa1 #afb2 hot springs1 #bd ,nukunase or ,nuku-ngase1 #ej1 #bgj ,nukumbalavu1 #aij ,nuku-ndamu1 #bcb ,numbu1 #bbg ,numbu-ni-a-vula1 #agf ,oddone on magnetic rocks1 #cfb ,oligoclase-trachytes1 #f1 #bjg1 #bai1 #bbi2 description of1 #cjh2 distribution1 #cgd2 altered1 #bad-baf2 columnar1 #bae1 #bbj1 #bcj1 #bca1 #bcc ,olivine rocks1 classification of1 #bci ,olivine-basalts2 see ,basalts1 olivine ,ono ,island1 hot springs1 #bb2 acid andesite1 #bic2 flints1 #cej ,onyx1 #aci1 #bbg1 #bbh1 #cec ,opal1 #afb1 #afc1 #ahc1 #cea1 #cec ,ophitic basalts1 their relation to palagonite1 #cdg ,ophitic structure1 as used in classification1 #bcf1 #bcg1 #bch ,ophitic sub-orders and genera1 synopsis of1 #bda-bdh2 description of1 #bef1 #bgb-bgf1 #bhc ,orthophyric groundmass1 as used in classification1 #bcf1 #bcg1 #bci1 #bdj ,orthophyric orders and genera1 #bdh1 #bij1 #bif1 #big1 #bii ,ovalau1 #bid1 #cej ,palagonite1 chapter on1 #ccg-cdi2 see also ,palagonite-tuffs1 ,crush-tuffs1 ,crushing of basic glass1 ,pitchstone c4 ,palagonite of ,acicastello1 #cdg ,palagonite tuffs1 classification and characters1 #cag-ccf2 zeolitic1 #ccd2 marls1 #cce1 #cdd2 modes of occurrence1 #e1 #dh1 #ec1 #hj1 #ha1 #ie1 #if1 #aag1 #aah-abb1 #acj1 #aca1 #ada1 #adc1 #ade1 #adh1 #aef-afa1 #afi1 #agg1 #aic1 #aih1 #bjb1 #bac ,palagonite1 hydration and degradation of1 #cbi1 #cdh ,phenocrysts1 their use in classification1 #bcf ,pickering1 ,mr41 #ce ,pieper1 ,dr4 ,o41 #bh ,pilsbry1 ,dr41 #chj ,pitchstone agglomerates and rubbly pitchstones1 petrological characters1 #cab1 #cac2 evidence of crushing and its connection with palagonite1 #ib-id1 #adb1 #ade1 #aeg1 #cab1 #cac1 #ccd1 #cdj-cdb1 #cdf 7see ,palagonite1 ,crush-tuffs1 ,crushing of basic glass72 mode of occurrence1 #aje1 #ajh1 #adb1 #aeg1 #afi1 #bbi1 #bcj1 #cji #agj,place-names1 meaning of ,fijian1 #ge1 #gi1 #ajb1 #aai1 #aea1 #agb ,platania1 ,prof41 #aai1 #cdg ,plutonic rocks1 general description1 #bdi-bea2 relative frequency1 #bce2 distribution1 #bdi1 #cgd2 mode of occurrence1 #ahj1 #ahb1 #ahd1 #ahe1 #aic1 #baa ,polarity of magnetic rocks1 #cff-cgj ,porphyrites1 #acf1 #age1 #aha1 #aig1 #aii1 #bjd1 #baa1 #bfa1 #bfh1 #bgd1 #bii2 belong to many orders1 #bcf ,prismatic pyroxene of groundmass1 its use in classification1 #bcf1 #bda-bdh2 sub-orders and genera1 #bfe1 #bgj-bgb1 #bhc1 #bhg1 #bhi1 #bih1 #cjj1 #cjb ,profiles of ,vanua ,levu1 #c-f1 #fb1 #hc1 #ajg1 #aac1 #aec1 #afg1 #agc ,propylites1 #fh-gb1 #ajf1 #adg1 #afb1 #aha1 #aia1 #aii1 #bjd1 #bad1 #bae1 #bfh-bgj1 #bhb1 #big2 origin of1 #fi1 #gb1 #aia ,pteropod-ooze deposits1 description of1 #cbj2 mode of occurrence1 #hd1 #hf1 #aji1 #aci1 #bja1 #bje1 #cdd ,pumice-tuffs1 acid1 #f1 #bjg1 #bah-bbc1 #bbi-bcc2 general description1 #ccf2 special descriptions1 #bah1 #bbj1 #bca ,pumice-tuffs1 basic1 #aai1 #ccc2 see ,hyalomelan-tuffs ,pyroxene of groundmass1 as a basis of classification1 #bcf2 see ,granular pyroxene1 ,prismatic pyroxene1 ,ophitic structure1 and ,synopsis ,pyroxene1 rhombic1 characters of1 #bhe1 #cjf2 intergrowths with monoclinic1 #bff1 #cjf ,pyroxene1 derivation from hornblende1 #cjf ,quartz1 crystals of1 #ajf1 #aia1 #ced2 veins of1 #ajf1 #aaf ,quartz-andesites2 see ,dacites ,quartz-porphyries1 mode of occurrence1 #bae1 #bai1 #bbj1 #bbf1 #bbg1 #bbi-bcc2 relative frequency1 #bce2 general description1 #cji-caa2 distribution1 #f1 #bjg1 #cgd ,quartz-rock1 #aci1 #cea1 #ced ,rainfall1 #cj1 #fh1 #abj ,rambi1 island1 #b2 hot springs1 #bb ,ravi-koro mountain1 #aei ,ravi-ravi1 #id ,ravuka1 #abj2 hot spring1 #ca ,renard1 ,prof41 #bic1 #cjf1 #cch1 #cdd ,rewa ,district in ,vanua ,levu1 #ie1 #if ,rewa ,river1 ,viti ,levu1 changes at mouth1 #af ,rhyolites1 #bji2 see ,quartz-porphyries ,rhyolite-glass1 #bbj1 #caa ,rhyolitic-tuffs2 see ,pumice-tuffs1 acid ,ridge-mountains1 their general appearance1 #b1 #f1 #adf1 #aec1 #ahe1 #baj1 #cgd2 their structure and mode of origin1 #ge1 #ade1 #aef1 #afe1 #aff1 #aga1 #agb1 #agg-ahj1 #ahb1 #ahh1 #bjb1 #baj-bab1 #baf1 #bcd2 final conclusion1 #cge ,rivers2 see under ,ndreketi1 ,lambasa ,sarawanga1 ,wainikoro1 c4 ,rivers1 eroding power of1 #fb ,rocholl1 ,mr4 ,h41 #bi ,rosenbusch1 ,prof41 #cjf1 #cdd ,ruku-ruku ,bay1 #ec1 #bfi ,salt ,lake ,district1 #b1 #f1 #i1 #aib-aif ,sarawanga ,plains1 #ae1 #abi-acb1 #cea1 #cef ,sarawanga ,river1 #ae1 #fb1 #abi-aca ,satulaki1 #agf1 #bfh ,savarekareka ,bay1 #aij1 #cbf ,savulu1 #aah ,savu-riti ,mountain1 #baj1 #bab ,savu-savu ,hot ,springs1 #ba1 #be-cj1 #ahi ,savu-savu ,peninsula1 #ahi-aib1 #bhh ,sawa-ndrondro1 #ahe ,scirpodendron costatum 7,giant ,sedge71 #gi1 #hc ,scoriaceous lava2 see ,lava flows ,sealevu ,district1 #adf1 #aee1 #aef ,sealevu ,divide1 #acf ,seatovo ,range1 #gc-ge ,seatura1 mountain1 #b1 #c1 #ef1 #bec1 #bfa1 #cgd2 general description of1 #fa-gb2 old town of1 #fg ,sections across ,vanua ,levu1 #fb1 #ajg2 see also ,profiles ,seemann1 ,dr41 #ee ,sella1 on magnetic rocks1 #cfb ,semi-opal1 #cea1 #cec ,sesaleka ,mountain1 #c1 #ab1 #ec ,siliceous concretions1 #ha1 #hc1 #if1 #acb1 #ace1 #cea-cee ,siliceous rock1 blocks of1 #abf1 #cee ,siliceous sinter1 #bd1 #be1 #cb1 #cc1 #cg1 #db ,silicification1 conditions of1 #ceh ,silicified corals1 #aj1 #ac1 #ha1 #acb1 #ace1 #ach1 #aci1 #bjg1 #bba1 #bbf-bbh2 theory of their origin1 #bbh1 #ceg2 general account of1 #cej-cfj ,silicified fern rhizome1 #cfj ,silicified nullipores1 #cec1 #ced ,singa-singa1 #aaj ,singatoka ,river1 ,viti ,levu1 #g ,skinner1 ,mr4 ,s41 #cfg ,skye1 ,isle of1 magnetic rocks1 #cfb ,smallwood1 ,mr41 #aif ,smythe1 ,colonel1 #bb1 #aie ,soapstones2 see ,foraminiferous deposits ,sokena ,ridge1 #afg1 #afi1 #agb ,solevu ,bay1 #ge-gh1 #bec ,solfataric action on rocks1 #eb1 #fi1 #gb1 #aia ,soloa-levu ,mountain1 #ajc-aje1 #aae1 #bif1 #cje1 #cab1 #cgd ,solomon ,islands1 #a1 #b1 #bid1 #cei ,songombiau1 #bbj ,soni-soni ,island1 #ic1 #id ,soro-levu ,mountain1 #agb-agd ,spence1 ,mr4 ,f41 #aic ,spheroidal weathering in basalts1 #eg1 #abi ,stromboli1 #bad1 #cae ,submarine basaltic flows and eruptions2 see ,basaltic submarine flows ,submarine plateau or platform of ,fiji1 #ae1 #ah1 #ai1 #ef1 #fb1 #gb1 #ajg1 #cgb2 different explanations of1 #cgc ,submarine tuffs1 #cbf-ccf ,sueni ,district1 #afc ,suess1 ,prof41 on thermal springs1 #ci2 on changes in the sea-level1 #bj1 #cgg ,suva soapstone1 #cbb1 #cgf ,synopsis of classification of volcanic rocks1 #bci-bdi ,tachylyte or basic glass1 #cab1 #ccg1 #cda1 #cdc2 see ,basic glass1 ,pitchstone1 ,hyalomelan1 c4 ,tahiti1 #c1 #gb1 #hd1 #cfc ,talasinga ,districts1 #ee1 #eg1 #fd1 #abh1 #acb1 #acc1 #bbd1 #ceb1 #chc ,tambia1 district1 #acg2 hot springs1 #cb ,tambu-lotu ,district1 #ajd1 #aje ,tathelevu1 #aih ,tavia1 mountain1 #aba2 ranges1 #aba-abc ,tavua1 #fe ,tawaki ,district1 #bji1 #bbi1 #bcj ,tembe1 #bac1 #bad ,tembe-ni-ndio ,district1 #acj1 #aca1 #cai ,tenison-,woods1 ,rev41 #cgf ,thambeyu1 mountain1 #e1 #afg1 #bhi1 #cae1 #cbf2 description of1 #agf-agi ,thawaro ,peak1 #bcj ,thermal springs2 see ,hot springs ,thiele1 ,mr41 #ba ,thoka-singa ,mountain1 #ajc1 #bdi1 #cjb1 #cje ,thombo-thombo2 see ,naithombothombo ,thomson1 ,mr4 ,j4 ,p41 #ca1 #ace1 #baj1 #bbe ,thongea1 hot springs1 #bb2 basalt1 #he ,thoroddsen1 on ,hekla1 #cge ,thuku1 ,mount1 #f1 #bca1 #cjh-caj ,thulanga2 see ,uthulanga ,thurston ,range1 #e1 #afg1 #agf2 see ,thambeyu ,tonga ,group1 #a1 #cgh1 #cgi ,tongalevu ,district1 #fb1 #fd1 #bgi ,towns1 old sites of mountain1 #ec1 #fg1 #aja1 #ajb1 #ajh1 #aef1 #agj ,trachytes2 see ,oligoclase-trachytes ,tuffs1 chapter on1 #cag-ccf2 foraminiferous1 #cbf-ccc2 altered1 #ahd1 #ahg1 #aij1 #ccb2 dacitic1 #abe1 #abf2 see ,pumice tuffs1 acid and basic2 ,hyalomelan tuffs2 ,palagonite tuffs2 ,crush tuffs2 mode of occurrence1 #dh1 #ij1 #aji1 #aai1 #acj1 #aef1 #afj1 #agg1 #aij1 #bje1 #bji1 #bae ,tunuloa ,district1 #bje ,tutu ,island1 #bba ,ulu-i-matua1 #ge1 #gf ,ulu-i-mbau1 #ach1 #aci ,ulu-i-ndali1 #c1 #hc1 #hg-ij1 #bec1 #cgj ,ulu-i-sori1 #acf ,underwood1 ,lieut41 #cfd ,undu1 district and promontory1 #f1 #aj1 #cf1 #bbh-bcd1 #caa1 #cfj ,upheaval2 see ,emergence ,urata1 #ahd1 #bih ,uthulanga ,ridge1 #baa1 #bhf 7also named ,thulanga7 ,vakalalatha ,lake1 #ae1 #bbe ,valanga ,range1 #aha-ahe ,valavala ,bay1 #bjc ,valeni1 #abb ,va ,lili1 #e1 #adj-adf ,valleys1 origin of1 #b1 #adf1 #aea1 #bai ,vandrani1 district1 #aci1 #aei2 hot springs1 #cb ,vanua ,mbalavu1 hot springs1 #bb ,variolite1 #aej1 #bhc1 #cac ,vatui1 #ed1 #cfi ,vatu ,kaisia1 #e1 #aac-aaf1 #bif1 #cja1 #cje1 #cgd1 #cge ,vatu-karoa1 #bji1 #bhb ,vatu-karokaro1 #ed ,vatu-kawa1 river1 #aea2 district1 #afj ,vatu-kerimasi1 #aja ,vatu-lele ,bay1 #ahd ,vatu-levoni1 #aci ,vatuloaloa ,hot ,springs1 #ca ,vatu ,mata1 #ajc ,vatu-ndamu1 #ia ,vatu-tangiri1 #acf1 #add ,vatu ,vanaya1 #aja ,vatu ,vono ,point1 #hh1 #hi ,vatu-vono ,district1 #aba1 #abb ,viene ,district1 #aih ,visongo ,district1 #bba ,viti ,levu1 #g1 #ah1 #cej1 #cfd1 #cgb ,vitina1 #bbc ,volcanic agglomerates1 general description of1 #cad-caf2 their thickness1 #aaj1 #aef1 #aga1 #agh1 #cae2 mode of occurrence1 #e1 #gi1 #ia1 #aaj1 #aab1 #aag1 #ada1 #adc1 #add1 #adi1 #aee1 #aef1 #afa1 #afi-agb1 #agf-agi1 #ahh1 #aic1 #bac1 #bad2 lying above submarine deposits usually palagonitic and often foraminiferous1 #aaj1 #ada1 #adc1 #adi1 #afh1 #afi-aga1 #agf-agi1 #ahh1 #bac1 #bad2 see ,pitchstone-agglomerates and ,landslips ,volcanic bomb-formation1 #df-dh ,volcanic mud deposits2 see ,foraminiferous deposits ,volcanic necks1 #ed1 #eh1 #ij1 #ic1 #ie1 #aab1 #ahc1 #aib1 #bcj1 #bcd1 #bec1 #bgg1 #bhc1 #bhf1 #cge ,volcanic rocks1 classification of1 #bce2 distribution of1 #cgd ,vuinandi ,bay1 #bjh ,vuinandi ,gap1 #age ,vuinasanga1 district1 #ade2 hot springs1 #ca ,vui-na-savu1 river and district1 #bbb1 #bbc1 #bbe ,vula ,votu ,peak1 #agf ,vungalei ,mountain1 #bab1 #bac1 #cae ,vuni-ika ,bay1 #bah ,vunikondi1 #bcb1 #bcc1 #bhb ,vunimbele1 #aci2 hot springs1 #cc ,vunimbua1 district and river1 #ahb1 #ahc ,vunimoli1 hot springs and district1 #cc1 #ach1 #aci ,vunisawana1 district1 #aid2 hot springs1 #cd ,vuni-tangaloa1 #aid ,vunivuvundi ,district1 #hg ,waikatakata1 ,natewa ,bay1 hot spring and district1 #cd1 #bjc1 #bge ,waikawa ,mountains1 #bja1 #cai ,wailea1 bay and district1 #df1 #ej ,wailevu ,river1 #ae1 #ach ,wai ,mbasanga1 ,viti ,levu1 hot springs1 #ba ,waimotu ,district1 #bjh ,wai ,ndina1 ,viti ,levu1 hot springs1 #ba ,wainikoro1 district1 #bag1 #bbd-bbh1 #cef2 coast1 #bai1 #cjh1 #caj2 river1 #bbe ,wai-ni-ngio ,river1 #aea1 #afj ,wainunu1 hot springs1 #bb2 rainfall #fh2 river and valley1 #fb1 #hb1 #hc ,wainunu1 plateau or tableland1 #c1 #hb-hg1 #cgc2 see figures on pages #hc1 #ajg ,waisali ,district1 #adf1 #aea ,waisali ,saddle1 #adf-adh ,waiwai1 #adc-ade ,waterfalls1 #gi1 #ada1 #afc ,wawa ,levu ,mountain1 #aja1 #cjb1 #cjd ,weed1 ,mr41 on the origin of siliceous sinter1 #ch ,wichmann1 ,dr4 ,a41 on a continental condition of the ,fiji ,islands1 #cgf2 on hyalomelan tuff1 #ccd2 on flints and silicified corals1 #cej1 #ceb1 #cfj2 on ,kandavu andesites1 #bic2 on the absence of quartz-andesites in the ,south ,seas1 #bid1 #cji2 see the preface ,wilkes1 ,commodore1 #aa1 #ae1 #ai1 #be1 #cfc1 etc4 ,wittstock1 ,mr41 #cf1 #dg1 #ec ,yanawai coast1 #ie-ig1 #abb ,yanawai1 river and valley1 #aac-aaf1 #aba ,yanganga ,islands1 #b ,yanutha ,point1 #abc1 #bhd ,yaroi1 #ahi1 #cbe ,yasawa ,group1 #bid ,zeolites1 formation of1 in palagonite1 #cch ,zeolitic palagonite-tuffs1 #ccd ,zirkel1 on intergrowths of rhombic pyroxene1 #cjf2 on palagonite1 #cdc2 on magnetic rocks1 #cfa ,,the ,,end ,r4 ,,clay ,,and ,,sons1 ,,ltd41 ,,bread ,,st4 ,,hill ,e4,c41 ,,and ,,bungay1 ,,suffolk4 --------------------- ,footnote #a3 ,in the case of the island of ,faro in the ,solomon ,group1 ,i have described a similar process of island-building4 7,geology of the ,solomon ,islands1 p4 #cg47 ,footnote #b3 ,in #ahig ,i spent several months in travelling over this island and ascended1 sometimes more than once1 the three great volcanic mountains4 ,perhaps at some future time ,i may renew my examination of this interesting region4 ,footnote #c3 ,strictly speaking ,korolevu indicated in the profile would not be visible4 ,footnote #d3 ,mariko is the native name of the ,drayton ,peak of the chart4 ,mbatini is the correct name for the ,koro ,mbasanga of the chart1 the true ,koro ,mbasanga lying three miles to the north4 ,thambeyu is a native name for the ,mount ,thurston ,range4 ,footnote #e3 ,there has been some confusion in the native names of the peaks in this part of the island1 which ,i have not been able to remove4 ,footnote #f3 ,a ,year in ,fiji1 #ahha1 pp4 #bb1 #afg4 ,footnote #g3 ,geology of the ,united ,states ,exploring ,expedition1 #ahdi4 ,footnote #h3 ,this height has been supplied from memory1 as ,i omitted to refer to the exact level of the erosion line in my notes4 ,footnote #i3 ,they were described to me as dry for a fortnight at a time4 ,i was prevented from making more than an occasional visit to them4 ,footnote #aj3 ,atlas of the ,united ,states ,exploring ,expedition1 vol4 i41 ,philadelphia1 #ahej4 ,footnote #aa3 ,this1 however1 is not the case with the recent changes at the mouth of the ,rewa ,river in ,viti ,levu1 where the bare sandy point of ,lauthala has extended itself seaward between #ejj and #fjj yards since #ahdj1 whilst ,port ,nukulau has shoaled a fathom in the same period4 ,but ,i can find no evidence of any marked advance in the mangrove margins either towards ,nukulau or on the ,kamba side1 the only change recognisable being in the bare sandy point of ,lauthala1 the rapid extension of which has been such as to attract the attention of residents1 both whites and natives4 ,dana1 who was in this locality in #ahdj1 remarks in the ,geology of the ,u4,s4 ,exploring ,expedition1 that he had learned from a person who had resided there for forty years that during this period the deposits had lengthened the river half a mile4 ,when ,i was on the ,rewa in #ahig ,i heard that the natives in old time could see ,suva ,point from ,rewa4 ,this is probably a native legend connected with the modern extension of ,lauthala ,point4 7,the charts compared in making the above measurement of the recent advance of this point were the plan of the ,rewa ,roads by ,wilkes1 in #ahdj1 and the ,admiralty charts #ageg and #ije1 the former of which was based on ,lieut4 ,dawson's survey in #ahge1 the last being corrected to #ahig47 ,footnote #ab3 ,between ,mathuata ,island and the coast a change is indicated from #i-aj fathoms to #h-i fathoms1 north of ,motua ,island #ab-ac to #aa-ab1 and between ,nangano and ,thakavi #af to #ad fathoms4 ,footnote #ac3 ,by referring to the chart it will be seen that extensive mud-flats occur at the mouths of the ,sarawanga and ,ndreketi rivers1 where the land-margin is slowly advancing4 ,footnote #ad3 ,united ,states ,exploring ,expedition1 vol4 x42 ,geology1 by ,j4 ,d4 ,dana1 p4 #cdc4 ,footnote #ae3 ,a ,year in ,fiji1 by ,john ,horne1 ,london1 #ahha1 p4 #afc4 ,footnote #af3 ,journal1 ,royal ,geographical ,society1 #aheg1 vol4 #bg4 ,footnote #ag3 ,scottish ,geographical ,magazine1 ,august1 #ahia4 ,footnote #ah3 ,journal des ,museum ,godeffroy1 heft #ad1 ,hamburg1 #ahgi4 ,footnote #ai3 ,dr4 ,max ,bchner also refers to this spring in his ,reise durch den ,stillen ,ozean1 #ahgh4 ,footnote #bj3 ,bulletin ,museum ,comparative ,zoology1 ,harvard1 vol4 #ch2 ,geolog4 ,series ,v41 ,no #a1 ,nov4 #aijj4 ,footnote #ba3 ,amongst the other descriptions of these springs ,i may refer to that of ,kleinschmidt in the work quoted on p4 #bb1 to that of ,miss ,gordon ,cumming in ,at ,home in ,fiji1 to that of ,horne in his ,year in ,fiji1 c4 ,they are sketched in the descriptions of ,kleinschmidt1 ,miss ,cumming1 and ,commodore ,wilkes4 ,the analyses are given on a later page together with the references4 ,footnote #bb3 ,pacific ,islands1 ,sailing ,directions1 vol4 ii41 ,central ,groups1 #aijj1 p4 #ahe4 ,footnote #bc3 ,from what ,i remember the usual exposure at low-water in #ahih was less than a foot4 ,i have little doubt as to the identity of the locality4 ,this rock is one of the 8sights0 of the place at the present time4 ,it would be interesting for a resident to compare carefully its present condition with that as described by ,wilkes4 ,dana in the work quoted on p4 #aj1 refers to this rock as a knoll of basalt2 but he never visited the locality and only obtained his account from the officers of ,wilkes4 ,footnote #bd3 ,narrative of the ,united ,states ,exploring ,expedition1 ,,iii41 #aii1 by ,commodore ,wilkes4 ,see also ,dana's ,geology of the same expedition4 ,footnote #be3 ,journal des ,museum ,godeffroy1 heft #ad1 ,hamburg1 #ahgi4 ,footnote #bf3 ,islands of the ,pacific1 by ,h4 ,stonehewer ,cooper1 #ahhh edition4 ,footnote #bg3 ,journal ,royal ,society1 ,new ,south ,wales1 #ahhj1 vol4 #ad4 ,miss ,gordon ,cumming in ,at ,home in ,fiji gives the same analysis but differently stated4 ,footnote #bh3 ,to avoid error1 ,i have given the results of each without converting them to a common standard4 ,the numbers in brackets are taken from the form of ,prof4 ,liversidge's analysis given in ,miss ,gordon ,cumming's book4 ,footnote #bi3 ,united ,states ,exploring ,expedition1 vol4 #aj1 ,geology4 ,footnote #cj3 ,proceedings1 ,queensland ,branch1 ,geographical ,society1 ,australia1 vol4 #a4 #ahhf4 ,footnote #ca3 ,i took the temperature at monthly intervals between ,october1 #ahif1 and ,september1 #ahig4 ,the mean annual temperature of the air in the shade would be about #fd at an elevation of between #c1jjj and #d1jjj feet4 ,footnote #cb3 ,at ,ewa there are pumping plants capable of supplying #ge million gallons a day1 the water being drawn entirely from artesian wells4 7,report on ,hawaii1 by ,dr4 ,stubbs1 bulletin #ie1 #aija2 ,u4,s4 ,department of ,agriculture47 ,footnote #cc3 ,this hill is figured in ,wilkes' narrative under the name of ,dillon's ,rock 7vol4 #c1 p4 #bce74 ,this1 however1 is not the ,dillon's ,rock of his chart1 where the name is given to a rock on the west side of the entrance to ,wailea ,bay4 ,footnote #cd3 ,see remarks on 8crush-tuffs0 on p4 #ccd4 ,footnote #ce3 ,species not identified4 ,footnote #cf3 ,in one of my traverses ,i crossed a level district extending a mile ,n4,e4 of ,ndriti without changing my elevation4 ,footnote #cg3 ,at ,delanasau1 on the north or dry coast of the island1 the average rainfall1 according to many years' observations by ,mr4 ,holmes1 is about #aae inches4 ,at ,wainunu1 near the wet or south coast1 the observations of ,mr4 ,barratt and others extending over #af years give an average of #afj inches4 ,in the mountains this would be nearly doubled4 ,footnote #ch3 ,this question1 which has so often been raised with respect to the propylites1 will probably receive a different answer from different localities4 ,the matter is further discussed on later pages4 ,footnote #ci3 ,the dyke-rock has a specific gravity of #bg2 but is slightly vesicular4 ,it shows a few small plagioclase phenocrysts in a groundmass of felspar-lathes1 augite grains and prisms1 magnetite1 and a little brown interstitial glass4 ,the felspar-lathes average #ad mm4 in length and are for the most part not parallel4 ,secondary calcite occurs in the groundmass1 and the powdered rock effervesces a little in an acid4 ,the rock forming the offshoot of the dyke differs only from the parent rock in its more vitreous character4 ,although the felspars and augites of the groundmass are fairly developed1 the residual glass is much more copious1 and in places where it has segregated1 forming 8lakelets10 it has been subjected to an alteration often observed in palagonite when there are concentric alternating zones of a tan-coloured fairly refractive material and calcite4 ,the reddish scoriaceous lava in contact with the dyke shows no phenocrysts4 ,the groundmass displays more or less parallel felspar-lathes1 #a mm4 long1 augite grains1 and much magnetite4 ,the residual glass is fair in quantity2 but is mostly gathered into 8lakelets0 of brown altered glass with sometimes calcite in the centre4 ,the vitreous border of the dyke is composed of a dark glass quite opaque in the outer portion1 but clearer and showing incipient crystallisation in the inner portion4 ,footnote #dj3 ,characteristics of ,volcanoes1 #ahij4 ,footnote #da3 ,referred to genus #af of the olivine-basalts4 ,footnote #db3 ,this subject is discussed in ,chapter ,,xxvi4 ,footnote #dc3 8,na ,savu0 is the ,fijian for waterfall4 ,the complete name of this fall is 8,na ,savu ni nuku40 ,footnote #dd3 ,the flinty concretions are described on page #ced1 and the iron sand on p4 #cef4 ,footnote #de3 ,geology of the ,united ,states ,exploring ,expedition4 ,footnote #df3 ,a similar arrangement was observed in the columnar basalt of ,kauai in the ,hawaiian ,islands4 ,it is presumed that these ,hawaiian flows are sub-arial4 ,footnote #dg3 ,the unaltered glass1 which incloses a few plagioclase phenocrysts1 has a specific gravity of #bg1 and is readily fusible4 ,footnote #dh3 ,they are described on p4 #cbb4 ,footnote #di3 ,this absence of a healthy forest-growth1 such as occurs on the level summit of the neighbouring ,soloa ,levu and in all like situations1 has probably some geological significance4 ,footnote #ej3 ,these tuffs are probably submarine4 ,they will be found described with tuffs of the same character on p4 #ccc4 ,footnote #ea3 ,the track attains an elevation of about #a1cjj feet1 but the top of the watershed is two or three hundred feet lower4 ,footnote #eb3 ,it belongs to the #crd order of the hornblende-hypersthene-andesites described on p4 #bii4 ,footnote #ec3 ,occasional views of its summit only are obtained from the eastward1 as from the ,ndrandramea mountains and their vicinity4 ,footnote #ed3 ,alluvial gold has long been known to occur in the bed of the ,yanawai below ,vatu ,kaisia2 but it has never been found in paying quantity4 ,footnote #ee3 ,under the microscope it is shown to be granular in structure1 exhibiting a mosaic of irregular quartz grains4 ,footnote #ef3 ,the blocks of the agglomerate in this last locality are from one to three feet across4 ,footnote #eg3 ,it displays in the groundmass augite prisms in flow-arrangement1 and is referred to genus #bj of the augite-andesites4 ,footnote #eh3 ,referred to genera #af and #bj of the augite-andesites4 ,footnote #ei3 ,these foraminiferal limestones are described on p4 #cai4 ,footnote #fj3 ,proceedings1 ,queensland ,branch1 ,geographical ,society of ,australasia1 ,brisbane1 #ahhf1 vol4 i4 ,footnote #fa3 ,geology of the ,united ,states ,exploring ,expedition4 ,footnote #fb3 ,pacific ,islands1 vol4 ii4 #aijj4 ,footnote #fc3 ,it is referred to the #eth sub-order 7genus #ah7 of the hypersthene-augite-andesites characterised by prismatic pyroxene and more or less parallel felspar lathes in the groundmass1 as described on p4 #bhi4 ,it displays abundant opaque porphyritic plagioclase giving extinctions of oligoclase-andesine4 ,the pyroxene phenocrysts have dark alteration-borders4 ,there is a little altered interstitial glass4 ,spec4 grav4 #bee4 ,footnote #fd3 ,i did not ascend to the top of ,ulu-i-mbau4 ,it is1 however1 evidently composed of basic andesitic rocks1 occasionally amygdaloidal4 ,on its slopes up to at least #fjj feet above the sea occur agglomerate-tuffs and finer submarine tuffs1 as above described1 overlying foraminiferous clays1 a submergence of quite #ejj feet being indicated by the investing deposits4 ,footnote #fe3 ,i did not find any foraminiferal shells or other organic remains either in this tuff or in the similar tuffs occurring on the adjacent slope of ,va-lili up to #a1ajj feet4 ,my specimens1 however1 are very small4 ,footnote #ff3 ,it rises in the background of the view4 ,footnote #fg3 ,they are described under sample ,e on p4 #ccb4 ,footnote #fh3 ,referred to genus #cg of the olivine-basalts4 ,footnote #fi3 ,on the right side of the river close to ,vatu-kawa there are some cliffs displaying a section of the mountainous spur1 referred to on p4 #aea1 that separates the valleys of the ,mbale-mbale and ,vatu-kawa rivers1 an exposure quite apart from the rocks exhibited on the adjacent southern slopes of the main range4 ,these cliffs are formed of bedded grey tuffs marked by single layers of blocks #f to #h inches across and dipping about #cj ,s4,s4,w4 ,the tuffs in their texture are not unlike sub-aerial tuff-deposits4 ,they contain no lime and are composed of basic materials with a little palagonite4 ,they seem to indicate some subsidiary vent1 close to the present village of ,vatu-kawa1 which may have been active shortly before or during the emergence of this district4 ,footnote #gj3 ,these altered tuffs on the southern slope of this range are described on p4 #ccb4 ,footnote #ga3 ,referred to genus #af1 species ,a1 sub-species #a1 of the augite-andesites4 ,footnote #gb3 ,referred to genus #i1 sub-genus ,a1 of the augite-andesites4 ,footnote #gc3 ,referred to genus #i1 sub-genus ,b1 of the augite-andesites4 ,footnote #gd3 ,both these rocks belong to the hypersthene-augite andesites1 showing phenocrysts of both monoclinic and rhombic pyroxene4 ,the first belongs to the orthophyric order described on p4 #bij2 whilst the second belongs to the second order 7genus #ac1 p4 #bhg7 where the felspars of the groundmass are lathe-like and in flow arrangement4 ,footnote #ge3 ,the highest dyke trends ,n4 #dh ,e4 and is inclined from the vertical about #ae ,n4,w4 ,the dyke1 #e or #f yards below it1 trends ,n4 #cj;,e4 and is vertical4 ,the dyke1 #ej yards farther down1 trends ,n4 #ce ,e4 and is inclined from the vertical about #e ,n4,w4 ,the inclination was only estimated4 ,the bearings are true4 ,footnote #gf3 ,both the types are referred to genus #a of the augite-andesites1 the olivine1 when present1 being quite insufficient to give a character to the rock4 ,they however belong to different species according to the length of the felspar-lathes1 which in the doleritic rocks averages #b mm4 and in the other type #jh mm4 ,footnote #gg3 ,it is pointed out on p4 #e that this name is wrongly applied in the ,admiralty charts to ,mount ,mbatini1 a mountain about three miles south of it4 ,footnote #gh3 ,referred to genus #ac of the augite-andesites4 ,footnote #gi3 ,they are blackish and somewhat compact 7sp4 gr4 #bfg-bga7 and have very small felspar-lathes less than #a mm4 long4 ,they contain both rhombic and monoclinic pyroxene1 and are referred to genera #a and #ac of the hypersthene-augite-andesites4 ,footnote #hj3 ,i discovered this error in a rather practical fashion by ascending the wrong mountain4 ,the natives were engaged to take me to ,koro-mbasanga and they performed their task1 my aneroid and compass soon indicating that ,i was not on the highest peak of the island1 but on a lesser peak three miles north of it4 ,footnote #ha3 ,vula ,votu is the name of a peak lying to the east4 ,ngoinangai is a forked mountain still further east4 ,footnote #hb3 ,a kind of 8edible0 bird's-nest is found in this cave4 ,footnote #hc3 ,this rock is described on p4 #bea4 ,footnote #hd3 ,it is described under ,sample ,c on p4 #cbe4 ,footnote #he3 ,it is granular1 but fuses in the blowpipe flame into a clear glass and gelatinises in ,h,cl4 ,probably a form of natrolite4 ,footnote #hf3 ,it is described under ,sample ,d on p4 #cbf4 ,footnote #hg3 ,ten ,months in ,fiji1 ,london1 #ahfd4 ,footnote #hh3 ,a ,year in ,fiji1 pp4 #aed1 #afi2 ,london1 #ahha4 ,footnote #hi3 ,it displays an abundance of small phenocrysts of plagioclase1 augite1 and olivine partly serpentinised1 in a groundmass composed in the main of coarse augite grains 7#jbe mm4 in size7 and of felspar microliths 7#jg mm4 in length7 in smaller proportion1 with little if any residual glass4 ,specific gravity #bih4 ,it is near the ,waikawa basalt1 referred to on p4 #bjb1 and is placed in the same genus 7#ac7 of the olivine class4 ,footnote #ij3 ,they are described on p4 #bfi under the non-porphyritic sub-genus of genus #b of the augite-andesites4 ,footnote #ia3 ,these rocks are in most cases referred to the orthophyric and felsitic orders of the hypersthene-augite andesites4 ,the rocks of the last-named order prevail1 and form the type of the group1 as described on p4 #bia4 ,footnote #ib3 ,it belongs to genus #cg of the olivine class4 ,the felspar-lathes average #jb mm4 in length1 and there is a little altered interstitial glass4 ,footnote #ic3 ,it is referred to genus #af1 species ,d1 of the augite-andesites4 ,the felspar-lathes have an average length of #c mm4 ,footnote #id3 ,proceedings1 ,queensland ,branch1 ,geographical ,society of ,australia1 vol4 i42 #ahhf4 ,footnote #ie3 ,referred to genus #i of the augite-andesites4 ,footnote #if3 ,the general characters of these rocks are described on p4 #cjh4 ,footnote #ig3 ,geology of the ,united ,states ,exploring ,expedition4 ,footnote #ih3 ,a ,year in ,fiji1 p4 #bb4 ,footnote #ii3 ,described on p4 #caj4 ,footnote #ajj3 ,these rocks are described on p4 #cjh4 ,footnote #aja3 ,it contains small phenocrysts of plagioclase 7medium andesine71 and of augite and rhombic pyroxene1 and is referred to genus #a of the hypersthene-augite andesites4 ,footnote #ajb3 ,see paper quoted on p4 #ca4 ,it is noteworthy that ,mr4 ,horne refers only to a single floating island4 ,footnote #ajc3 ,journal1 ,royal ,geographical ,society1 ,june1 #ahid4 ,footnote #ajd3 ,described on p4 #cji4 ,footnote #aje3 ,described on p4 #caj4 ,footnote #ajf3 ,referred to genus #ac of the augite-andesites4 ,the felspar-lathes average #a mm4 in length1 and there is a little interstitial glass4 ,footnote #ajg3 ,referred to genus #af of the augite-andesites4 ,there are two sets of felspar-lathes in the groundmass2 the larger1 #bc mm4 long1 are more or less parallel2 the smaller1 #jd mm4 long1 form a plexus4 ,footnote #ajh3 ,each division would theoretically also possess an orthophyric and a felsitic order2 but these orders are not represented in my collection and need only be mentioned4 ,footnote #aji3 ,not represented in the collection4 ,footnote #aaj3 ,i apply the term 8diorite0 to granitoid rocks formed entirely of plagioclase and hornblende4 ,footnote #aaa3 ,according to the size of the plagioclase phenocrysts1 whether averaging less than or more than #c mm4 in size1 these rocks may be divided into a non-porphyritic and a porphyritic sub-genus4 ,footnote #aab3 ,petrographie des ,viti ,archipels2 ,miner4 und ,petrogr4 ,mittheil2 band v1 heft #a1 ,wien1 #ahhb4 ,footnote #aac3 ,physics and ,chemistry1 ,,ii4 ,report ,scient4 ,results2 ,h4,m4,s4 ,challenger2 ,london1 #ahhi4 ,footnote #aad3 ,petrographical ,notes on the ,fiji ,islands2 ,proceed4 ,amer4 ,acad4 ,arts and ,sciences2 vol4 #cd2 no4 #ba2 ,may1 #ahii4 ,footnote #aae3 ,notes on the ,limestones and ,general ,geology of the ,fiji ,islands1 ,bull4 ,mus4 ,comp4 ,zool1 vol4 #e4 ,geolog4 ,ser4 vol4 #e1 no4 #a1 ,cambridge1 ,mass41 ,u4,s4,a4 ,nov4 #aijj4 ,footnote #aaf3 ,wichmann describes rocks from the cliffs of the ,singatoka river and from ,ovalau4 ,footnote #aag3 ,geology of the ,solomon ,islands1 by ,h4 ,b4 ,guppy1 #ahhg1 pp4 #f1 #cf4 ,footnote #aah3 ,the term 8felsitic andesite0 is suitable for this microfelsitic type4 ,footnote #aai3 ,i have borrowed this term from ,rosenbusch's ,microscopical ,physiography of the ,rock-making ,minerals1 translated by ,iddings4 ,footnote #abj3 ,challenger ,reports1 ,physics and ,chemistry ,,ii4 ,footnote #aba3 ,neues ,jahrb4 fur ,mineralogie1 #ahhd4 ,footnote #abb3 ,for their mode of occurrence1 see pp4 #bae1 #bbj1 #bcj-bcc4 ,footnote #abc3 ,highly altered rocks of this class are exposed at the base of ,mount ,nailotha as described on p4 #bae4 ,footnote #abd3 ,see work quoted on p4 #bah4 ,footnote #abe3 ,see p4 #bcj4 ,footnote #abf3 ,quart4 ,journ4 ,geolog4 ,soc4 xliv4 #ahhh4 ,footnote #abg3 ,zirkel's ,petrographie1 iii41 #fid4 ,footnote #abh3 ,this basalt is not fusible in the ordinary blow-pipe flame4 ,footnote #abi3 ,in this connection see the description of the ,soloa-levu pitchstone on p4 #cab4 ,footnote #acj3 ,see the note at the end of this chapter4 ,footnote #aca3 ,quoted in ,zirkel's ,petrographie1 iii41 #fhi4 ,footnote #acb3 ,i have visited this locality on several occasions with the special object of studying the relation of the basalt to the associated palagonite-tuffs and clays4 ,a general discussion of this question would be out of place here2 but ,i may remark that the conclusion arrived at by me is that these deposits are not sedimentary but are entirely the result of the disintegration of palagonite in situ4 ,this is quite opposed to the view of their sedimentary origin held by ,dr4 ,johnston-,lavis1 ,prof4 ,platania1 and other ,italian geologists4444 ,the basalt is scoriaceous1 semi-vitreous1 and semi-ophitic1 and closely approaches the type of basalt above defined4 ,footnote #acc3 ,reisen auf den ,viti-,inseln1 as quoted on p4 #bb4 ,footnote #acd3 ,petrographie des ,viti-,archipels1 quoted on p4 #bic4 ,footnote #ace3 ,see work quoted on p4 #cgh4 ,footnote #acf3 ,solomon ,islands and their ,natives1 by ,h4 ,b4 ,guppy1 p4 #gh4 ,footnote #acg3 ,the region is described on pp4 #bbd-bbh4 ,footnote #ach3 ,for the meaning of 8talasinga0 see p4 #ee4 ,footnote #aci3 ,the portion exhibiting the coral structure has a specific gravity of #bed4 ,footnote #adj3 ,a good list of references to the early ,german authorities on the subject is given in the ,american ,journal of ,science and ,arts for #ahca1 vol4 #bj4444 ,zirkel in his ,lehrbuch der ,petrographie 7#ahic1 vol4 i4 p4 #efe7 gives most of these and many more recent4444 ,harker in his paper below named refers to a review of the earlier literature in ,verh4 naturh4 ,vereins4 ,bonn1 #ahea1 vol4 #h1 and to a more complete bibliography by ,meli in ,boll4 ,soc4 ,geol4 ,ital4 #ahha1 vol4 #i4444 ,british ,association ,report in #ahhi by ,professors ,rcker and ,thorpe on the ,magnetic ,state of the ,british ,isles4444 ,nature for ,august and ,september1 #ahid1 c4444 ,harker on magnetic disturbances in the ,isle of ,skye1 ,proc4 ,cambr4 ,philos4 ,soc4 vol4 #aj1 part #e4444 ,skinner in ,proc4 ,cambr4 ,philos4 ,soc4 ,may1 #ahid4444 ,clark in ,journ4 ,roy4 ,instit4 ,cornwall1 #ahij-ic4444 ,folgheraiter in ,frammenti concernanti la geofisica1 ,rome3 referred to in ,nature1 ,july #bg1 #ahii1 and ,nov4 #h1 #aijj4 ,footnote #ada3 ,nearly all volcanic rocks at all basic are magnetic1 owing to the constant presence of magnetite2 but magnetic polarity1 when the rock-fragment has a negative and a positive pole1 is not directly concerned in volcanic rocks with the mineral composition4 ,footnote #adb3 ,some of the earliest observations were made on granites and trachytes4 ,footnote #adc3 ,geology of the ,united ,states ,exploring ,expedition1 #ahdi1 p4 #bid4 ,footnote #add3 ,quarterly journal ,geological ,society1 vol4 li41 p4 #dfi4 ,footnote #ade3 ,wilkes' ,narrative of the ,u4,s4 ,exploring ,expedition1 iii41 #ahe4 ,footnote #adf3 ,of the tuffs and clays1 almost all submarine and often containing tests of foraminifera and sometimes molluscan shells1 about #ij per cent4 exhibit simple magnetism in a slight degree1 but out of nearly #ajj specimens tested none show polarity4 ,footnote #adg3 ,on p4 #ceg will be found some notes on the magnetic iron sand that occurs in great abundance in river and stream beds4 ,footnote #adh3 ,these values represent the number of degrees that the magnetic needle is repelled4 ,the method is described above4 ,a note on the average amount of polarity found in all my polaric rocks is given at the end of the chapter4 ,the term 8dacite0 is here an equivalent of 8felsitic andesite40 ,footnote #adi3 ,this name has been wrongly applied in the ,admiralty chart to the mountain of ,mbatini4 ,koro-mbasanga1 #b1ejj feet1 lies three miles to the north4 ,footnote #aej3 ,this rock is described on p4 #aji4 ,there is no exceptional development of magnetite for a basic rock in the groundmass4 ,footnote #aea3 ,unfortunately1 ,i have no data for the peaks of ,na ,raro and ,vatu ,kaisia1 except that specimens obtained below the summits are non-polaric4 ,in the case of ,na ,raro ,i did not retain the specimen obtained at the top2 whilst in my ascent of ,vatu ,kaisia ,i did not quite reach the summit4 ,footnote #aeb3 ,the mode of measurement is described on p4 #cff4 ,footnote #aec3 ,see pp4 #b1 #ae1 #ah1 #ef1 #fb1 #gb1 c4 ,footnote #aed3 ,the ,islands and ,coral ,reefs of ,fiji1 ,bull4 ,mus4 ,comp4 ,zool4 ,harv4 ,coll4 vol4 #cc1 #ahii4 ,footnote #aee3 ,scott4 ,geogr4 ,mag4 #ahie4 ,footnote #aef3 ,ancient ,volcanoes of ,great ,britain1 by ,sir ,a4 ,geikie1 #ahig1 ii4 #bfj4 ,footnote #aeg3 ,see ,wichmann in ,min4 und ,petrog4 ,mitth4 band v4 heft #a4 ,footnote #aeh3 ,amer4 ,journ4 ,sci4 ,,vi4 #afe1 #ahih4 ,see also ,agassiz on the ,islands and ,coral ,reefs of ,fiji1 before quoted4 ,footnote #aei3 ,proc4 ,linn4 ,soc4 ,n4,s4,w4 #ahgi-hj1 p4 #ceh4 ,footnote #afj3 ,quart4 ,journ4 ,geolog4 ,soc4 vol4 #dd1 #ahhh4 ,footnote #afa3 ,see ,preface to the report of ,mr4 ,andrews quoted on a later page4 ,footnote #afb3 ,das ,antlitz der ,erde1 ,french edition by ,e4 de ,margerie1 ii4 #ecd4 ,footnote #afc3 ,see the paper before quoted on the coral reefs of ,fiji4 ,footnote #afd3 ,bull4 ,mus4 ,comp4 ,zool4 ,harv4 ,coll4 vol4 #ch4 ,geolog4 ,ser4 vol4 #e1 no4 #a1 #aijj4 ,on the ,limestones and ,general ,geology of the ,fiji ,islands1 by ,e4 ,c4 ,andrews4 ,footnote #afe3 ,quart4 ,journ4 ,geolog4 ,soc4 vol4 #dg1 p4 #eij1 #ahia4 ,see also ,mr4 ,harker's paper below quoted4 ,footnote #aff3 ,geolog4 ,mag4 ,june1 #ahia4 ,footnote #afg3 ,seemann's ,flora ,vitiensis1 ,horne's ,year in ,fiji1 ,hillebrand's ,flora of the ,hawaiian ,islands1 ,hemsley's 8,flora of the ,tonga ,islands0 in ,journal ,linnean ,society1 ,botany1 vol4 #cj4 ,footnote #afh3 ,see ,hutton ,proc4 ,linn4 ,soc4 ,n4,s4,w4 #ahif1 ,baur1 ,amer4 ,nat4 #ahig1 ,pilsbry1 ,proc4 ,nat4 ,sci4 ,philad4 #aijj1 ,hedley1 ,proc4 ,linn4 ,soc4 ,n4,s4,w4 #ahib1 #ahii1 c4 ,footnote #afi3 ,the term 8basalt0 is here used in a general sense to include olivine-basalts1 basaltic andesites1 and other basic types of the augite-andesites and hypersthene-augite andesites4 ,footnote #agj3 ,the usual signification of 8koro0 as a prefix or part of names of hills and mountains is a 8prominence0 or 8projection40 ,it is a mistake on my part to assume that in such cases it is as a rule equivalent to a town or village4 --------------------- ,transcriber's ,note ,there is some inconsistent spelling and hyphenation in this book which has not been normalized4 ,some corrections have been made to the text4 ,in particular1 punctuation was corrected4 ,additionally1 the following changes have been made3 p4 #aj beween - between p4 #ge #ae m4 long - #ae mm4 long p4 #aad ts - its p4 #bjh aud - and p4 #bdd ,pyroxyene - ,pyroxene p4 #bgj adoped - adopted p4 #cde tea-estat - tea-estate