,,coral ,,reefs      ,by ,charles       
,darwin          ,,contents             
,,detailed ,,table ,,of ,,contents      
,,description ,,of ,,the ,,plates       
,,the ,,structure ,,and ,,distribution  
,,of ,,coral ,,reefs    ,,introduction  
,,chapter ,i4--,,atolls ,,or            
,,lagoon-,,islands    ,,chapter         
,,ii4--,,barrier ,,reefs    ,,chapter   
,,iii4--,,fringing ,,or ,,shore-,,reefs 
,,chapter ,,iv4--,,on ,,the             
,,distribution ,,and ,,growth ,,of      
,,coral-,,reefs    ,,chapter            
,v4--,,theory ,,of ,,the ,,formation    
,,of ,,the ,,different ,,classes ,,of   
,,coral-,,reefs    ,,chapter ,,vi4--,,on
 ,,the ,,distribution ,,of              
,,coral-,,reefs ,,with ,,reference ,,to 
,,the  ,,theory ,,of ,,their ,,formation
    ,,appendix    ,,index               
,,detailed ,,table ,,of ,,contents      
,,description ,,of ,,the ,,plates       
,,introduction      ,,chapter           
,i4--,,atolls ,,or ,,lagoon-,,islands   
,,section ,i4--,,description ,,of       

,,keeling ,,atoll4 ,corals on the outer 
margin4--,zone of ,nullipor4--,exterior 
reef4--,islets4--,coral-conglomerate4--,
lagoon4--,calcareous sediment4--,scari  
and ,holuthuri subsisting on            
corals4--,changes in the condition of   
the  reefs and islets4--,probable       
subsidence of the atoll4--,future state 
of the  lagoon4    ,,section            
,,ii4--,,general ,,description ,,of     
,,atolls4 ,general form and size of     
atolls1 their reefs and                 
islets4--,external slope4-- ,zone of    
,nullipor4--,conglomerate4--,depth of   
lagoons4--,sediment4--,reefs submerged  
wholly or in part4--,breaches in the    
reef4--,ledge-formed shores round       
certain lagoons4--,conversion of lagoons
 into land4    ,,section                
,,iii4--,,atolls ,,of ,,the ,,maldiva   
,,archipelago--,,great ,,chagos ,,bank4 
,maldiva ,archipelago4--,ring-formed    
reefs1 marginal and central4--,great    
depths in the lagoons of the southern   
atolls4--,reefs in the lagoons all      

rising to the surface4--,position of    
islets and breaches in the reefs1  with 
respect to the prevalent winds and      
action of the  waves4--,destruction of  
islets4--,connection in the position and
 submarine  foundation of distinct      
atolls4--,the apparent disseverment of  
large  atolls4--,the ,great ,chagos     
,bank4--,its submerged condition and    
extraordinary structure4      ,,chapter 
,,ii4--,,barrier ,,reefs  ,closely      
resemble in general form and structure  
atoll-reefs4--,width and  depth of the  
lagoon-channels4--,breaches through the 
reef in front of  valleys1 and generally
 on the leeward side4--,checks to the   
filling up of  the                      
lagoon-channels4--,size and constitution
 of the encircled islands4--  ,number of
 islands within the same                
reef4--,barrier-reefs of ,new ,caledonia
  and ,australia4--,position of the reef
 relative to the slope of the  adjoining
 land4--,probable great thickness of    
barrier-reefs4      ,,chapter           

,,iii4--,,fringing ,,or ,,shore-,,reefs 
,reefs of ,mauritius4--,shallow channel 
within the reef4--,its slow filling     
up4--,currents of water formed within   
it4--,upraised reefs4--,narrow          
fringing-reefs in deep seas4--,reefs on 
the coast of ,e4 ,africa and of         
,brazil4--,fringing-reefs in very       
shallow seas1 round banks of sediment   
and on worn-down                        
islands4--,fringing-reefs affected by   
currents of the  sea4 --,coral coating  
the bottom of the sea1 but not forming  
reefs4      ,,chapter ,,iv4--,,on ,,the 
,,distribution ,,and ,,growth ,,of      
,,coral-,,reefs    ,,section ,i4--,,on  
,,the ,,distribution ,,of               
,,coral-,,reefs1 ,,and ,,on ,,the       
,,conditions  ,,favourable ,,to ,,their 
,,increase4    ,,section ,,ii4--,,on    
,,the ,,rate ,,of ,,growth ,,of         
,,coral-,,reefs4    ,,section           
,,iii4--,,on ,,the ,,depths ,,at ,,which
 ,,reef-,,building ,,polypifers ,,can   
,,live4      ,,chapter ,v4--,,theory    

,,of ,,the ,,formation ,,of ,,the       
,,different ,,classes ,,of              
,,coral-,,reefs  ,the atolls of the     
larger archipelagoes are not formed on  
submerged  craters1 or on banks of      
sediment4--,immense areas interspersed  
with  atolls4--,recent changes in their 
state4--,the origin of barrier-reefs and
  of atolls4--,their relative           
forms4--,the step-formed ledges and     
walls round  the shores of some         
lagoons4--,the ring-formed reefs of the 
,maldiva  atolls4--,the submerged       
condition of parts or of the whole of   
some  annular reefs4--,the disseverment 
of large atolls4--,the union of atolls  
by  linear reefs4--,the ,great ,chagos  
,bank4--,objections1 from the area and  
amount of subsidence required by the    
theory1 considered4--,the probable      
composition of the lower parts of       
atolls4      ,,chapter ,,vi4--,,on ,,the
 ,,distribution ,,of ,,coral-,,reefs    
,,with ,,reference ,,to ,,the  ,,theory 
,,of ,,their ,,formation  ,description  

of the coloured map4--,proximity of     
atolls and  barrier-reefs4-- ,relation  
in form and position of atolls with     
ordinary  islands4--,direct evidence of 
subsidence difficult to be              
detected4--,proofs  of recent elevation 
where fringing-reefs                    
occur4--,oscillations of                
level4--,absence of active volcanoes in 
the areas of  subsidence4--,immensity of
 the areas which have been elevated and 
have  subsided4--,their relation to the 
present distribution of the             
land4--,areas  of subsidence elongated1 
their intersection and alternation with 
those  of elevation4--,amount and slow  
rate of the                             
subsidence4--,recapitulation4           
,,appendix      ,,index                 
,,description ,,of ,,the ,,plates4      
,,plate ,i4          ,illustration3     
,,plate ,i4--,,map ,,showing ,,the      
,,resemblance ,,in ,,form ,,between     
,,barrier ,,coral-,,reefs ,,surrounding 
,,mountainous ,,islands1 ,,and ,,atolls 

,,or  ,,lagoon ,,islands4      ,in the  
several original surveys1 from which the
 small plans on this  plate have been   
reduced1 the coral-reefs are engraved in
 very different  styles4 ,for the sake  
of uniformity1 ,i have adopted the style
 used in  the charts of the ,chagos     
,archipelago1 published by the ,east    
,indian  ,company1 from the survey by   
,captain ,moresby and ,lieutenant       
,powell4 ,the  surface of the reef1     
which dries at low water1 is represented
 by a  surface with small crosses3 the  
coral-islets on the reef are marked by  
small linear spaces1 on which a few     
cocoa-nut trees1 out of all  proportion 
too large1 have been introduced for the 
sake of clearness4  ,the entire annular 
reef1 which when surrounding an open    
expanse of  water1 forms an 8atoll10 and
 when surrounding one or more high      
islands1  forms an encircling           
8barrier-reef10 has a nearly uniform    
structure4 ,the  reefs in some of the   
original surveys are represented merely 

by a  single line with crosses1 so that 
their breadth is not given2 ,i have  had
 such reefs engraved of the width       
usually attained by coral-reefs4 ,i     
have not thought it worth while to      
introduce all those small and very      
numerous reefs1 which occur within the  
lagoons of most atolls and  within the  
lagoon-channels of most barrier-reefs1  
and which stand  either isolated1 or are
 attached to the shores of the reef or  
land4 ,at  ,peros ,banhos none of the   
lagoon-reefs rise to the surface of the 
water2  a few of them have been         
introduced1 and are marked by plain     
dotted  circles4 ,a few of the deepest  
soundings are laid down within each     
reef2  they are in fathoms1 of six      
,english feet4    ,figure               
#a4--,,vanikoro1 situated in the western
 part of the ,south ,pacific2  taken    
from the survey by ,captain ,d',urville 
in the ,astrolabe2 the  soundings on the
 southern side of the island1 namely1   
from thirty to  forty fathoms1 are given

 from the voyage of the ,chev4 ,dillon2 
the other  soundings are laid down from 
the survey by ,d',urville2 height of the
  summit of the island is #c1jcb feet4  
,the principal small detached reefs     
within the lagoon-channel have in this  
instance been represented4 ,the         
southern shore of the island is narrowly
 fringed by a reef3 if the  engraver had
 carried this reef entirely round both  
islands1 this figure  would have served 
7by leaving out in imagination the      
barrier-reef7 as a  good specimen of an 
abruptly-sided island1 surrounded by a  
reef of the  fringing class4    ,figure 
#b4--;,,hogoleu1 or ,,roug1 in the      
,caroline ,archipelago2 taken from the  
atlas of the voyage of the ,astrolabe1  
compiled from the surveys of  ,captains 
,duperrey and ,d',urville2 the depth of 
the immense lagoon-like  space within   
the reef is not known4    ,figure       
#c4--,,raiatea1 in the ,society         
,archipelago2 from the map given in  the
 quarto edition of 8,cook's ,first      

,voyage20 it is probably not  accurate4 
,figure #d4--;,,bow1 or ,,heyou ,,atoll 
7or lagoon-island71 in the ,low         
,archipelago1 from the survey by        
,captain ,beechey1 ,r4,n42 the lagoon is
  choked up with reefs1 but the average 
greatest depth of about twenty  fathoms1
 is given from the published account of 
the voyage4    ,figure #e4--;,,bolabola1
 in the ,society ,archipelago1 from the 
survey of  ,captain ,duperrey in the    
,coquille3 the soundings in this and the
  following figures have been altered   
from ,french feet to ,english  fathoms2 
height of highest point of the island   
#d1jbf feet4    ,figure #f4--,,maurua1  
in the ,society ,archipelago2 from the  
survey by  ,captain ,duperrey in the    
,coquille3 height of land about eight   
hundred  feet4    ,figure               
#g4--,,pouynip,,te1 or ,,seniavine1 in  
the ,caroline ,archipelago2 from  the   
survey by ,admiral ,lutk4    ,figure    
#h4--;,,gambier ,,islands1 in the       
southern part of the ,low ,archipelago2 

from the survey by ,captain ,beechey2   
height of highest island1 #a1bdf  feet2 
the islands are surrounded by extensive 
and irregular reefs2 the  reef on the   
southern side is submerged4    ,figure  
#i4--,,peros ,,banhos ,,atoll 7or       
lagoon-island71 in the ,chagos group in 
the ,indian ,ocean2 from the survey by  
,captain ,moresby and ,lieutenant       
,powell2 not nearly all the small       
submerged reefs in the lagoon are       
represented2 the annular reef on the    
southern side is submerged4    ,figure  
#aj4--,,keeling1 or ,,cocos ,,atoll 7or 
lagoon-island71 in the ,indian  ,ocean2 
from the survey by ,captain ,fitzroy2   
the lagoon south of the  dotted line is 
very shallow1 and is left almost bare at
 low water2 the  part north of the line 
is choked up with irregular reefs4 ,the 
annular  reef on the north-west side is 
broken1 and blends into a shoal         
sandbank1 on which the sea breaks4      
,,plate ,,ii4--,,great ,,chagos ,,bank1 
,,new ,,caledonia1 ,,menchikoff ,,atoll1

 ,,etc4          ,illustration3 ,plate  
#b      ,figure #a4--;,,great ,,chagos  
,,bank1 in the ,indian ,ocean2 taken    
from the survey  by ,captain ,moresby   
and ,lieutenant ,powell2 the parts which
 are shaded1  with the exception of two 
or three islets on the western and      
northern  sides1 do not rise to the     
surface1 but are submerged from four to 
ten  fathoms2 the banks bounded by the  
dotted lines lie from fifteen to  twenty
 fathoms beneath the surface1 and are   
formed of sand2 the central  space is of
 mud1 and from thirty to fifty fathoms  
deep4    ,figure #b4--;,a vertical      
section1 on the same scale1 in an       
eastern and  western line across the    
,great ,chagos ,bank1 given for the sake
 of  exhibiting more clearly its        
structure4    ,figure #c4--,,menchikoff 
,,atoll 7or lagoon-island71 in the      
,marshall  ,archipelago1 ,northern      
,pacific ,ocean2 from ,krusenstern's    
8,atlas of the  ,pacific20 originally   
surveyed by ,captain ,hagemeister2 the  

depth within  the lagoons is unknown4   
,figure #d4--,,mahlos ,,mahdoo ,,atoll1 
together with ,horsburgh atoll1 in the  
,maldiva ,archipelago2 from the survey  
by ,captain ,moresby and ,lieutenant    
,powell2 the white spaces in the middle 
of the separate small reefs1  both on   
the margin and in the middle part1 are  
meant to represent  little lagoons2 but 
it was found not possible to distinguish
 them  clearly from the small islets1   
which have been formed on these same    
small reefs2 many of the smaller reefs  
could not be introduced2 the  nautical  
mark 7dot over a dash7 over the figures 
#bej and #bjj1 between  ,mahlos ,mahdoo 
and ,horsburgh atoll and ,powell's      
island1 signifies that  soundings were  
not obtained at these depths4    ,figure
 #e4--,,new ,,caledonia1 in the western 
part of the ,pacific2 from              
,krusenstern's 8,atlas10 compiled from  
several surveys2 ,i have slightly       
altered the northern point of the reef1 
in accordance with the 8,atlas  of the  

,voyage of the ,astrolabe40 ,in         
,krusenstern's 8,atlas10 the reef  is   
represented by a single line with       
crosses2 ,i have for the sake of        
uniformity added an interior line4      
,figure #f4--,,maldiva ,,archipelago1 in
 the ,indian ,ocean2 from the survey by 
,captain ,moresby and ,lieutenant       
,powell4    ,,plate ,,iii4--,,map       
,,showing ,,the ,,distribution ,,of     
,,coral-,,reefs ,,and ,,active          
,,volcanoes4          ,illustration3    
,plate #c ,shewing the ,distribution of 
the ,different ,kinds  of ,coral ,reefs1
 ,together with the ,position of the    
,active ,volcanoes in  the ,map4        
,the principles1 on which this map was  
coloured1 are explained in the          
beginning of ,chapter ,,vi42 and the    
authorities for each particular spot    
are detailed in the ,appendix to 8,coral
 ,reefs40 ,the names not printed in     
upper case in the ,index refer to the   
,appendix4          ,,the ,,structure   
,,and ,,distribution ,,of ,,coral       

,,reefs4          ,,introduction4       
,the object of this volume is to        
describe from my own observation and    
the works of others1 the principal kinds
 of coral-reefs1 more  especially those 
occurring in the open ocean1 and to     
explain the origin  of their peculiar   
forms4 ,i do not here treat of the      
polypifers1 which  construct these vast 
works1 except so far as relates to their
  distribution1 and to the conditions   
favourable to their vigorous  growth4   
,without any distinct intention to      
classify coral-reefs1 most  voyagers    
have spoken of them under the following 
heads3  8lagoon-islands10 or 8atolls10  
8barrier0 or 8encircling reefs10 and    
8fringing0 or 8shore-reefs40 ,the       
lagoon-islands have received much the   
most attention2 and it is not           
surprising1 for every one must be struck
  with astonishment1 when he first      
beholds one of these vast rings of      
coral-rock1 often many leagues in       
diameter1 here and there surmounted  by 

a low verdant island with dazzling white
 shores1 bathed on the  outside by the  
foaming breakers of the ocean1 and on   
the inside  surrounding a calm expanse  
of water1 which from reflection1 is of a
  bright but pale green colour4 ,the    
naturalist will feel this  astonishment 
more deeply after having examined the   
soft and almost  gelatinous bodies of   
these apparently insignificant          
creatures1 and when  he knows that the  
solid reef increases only on the outer  
edge1 which  day and night is lashed by 
the breakers of an ocean never at rest4 
,well  did ,franois ,pyrard de ,laval1  
in the year #afje1 exclaim1 8,c'est une 
merueille de voir chacun de ces         
atollons1 enuironn d'un grand banc de   
pierre tout autour1 n'y ayant point     
d'artifice humain40 ,the  accompanying  
sketch of ,whitsunday island1 in the    
,south ,pacific1 taken  from ,captain   
,beechey's admirable 8,voyage10 although
 excellent of its  kind1 gives but a    
faint idea of the singular aspect of one

 of these  lagoon-islands4              
,illustration    ,whitsunday ,island is 
of small size1 and the whole circle has 
been  converted into land1 which is a   
comparatively rare circumstance4 ,as the
  reef of a lagoon-island generally     
supports many separate small islands1   
the word 8island10 applied to the whole1
 is often the cause of  confusion2 hence
 ,i have invariably used in this volume 
the term  8atoll10 which is the name    
given to these circular groups of       
coral-islets by their inhabitants in the
 ,indian ,ocean1 and is  synonymous with
 8lagoon-island40    ,illustration      
,barrier-reefs1 when encircling small   
islands1 have been comparatively  little
 noticed by voyagers2 but they well     
deserve attention4 ,in their  structure 
they are little less marvellous than    
atolls1 and they give a  singular and   
most picturesque character to the       
scenery of the islands  they surround4  
,in the accompanying sketch1 taken from 
the 8,voyage of  the #8,coquille'10 the 

reef is seen from within1 from one of   
the high  peaks of the island of        
,bolabola4#a ,here1 as in ,whitsunday   
,island1 the  whole of that part of the 
reef which is visible is converted into 
land4  ,this is a circumstance of rare  
occurrence2 more usually a snow-white   
line of great breakers1 with here and   
there an islet crowned by  cocoa-nut    
trees1 separates the smooth waters of   
the lagoon-like channel  from the waves 
of the open sea4 ,the barrier-reefs of  
,australia and of  ,new ,caledonia1     
owing to their enormous dimensions1 have
 excited much  attention3 in structure  
and form they resemble those encircling 
many of  the smaller islands in the     
,pacific ,ocean4     #a ,i have taken   
the liberty of simplifying the          
foreground1 and   leaving out a         
mountainous island in the far distance4 
,with respect to fringing1 or           
shore-reefs1 there is little in their   
structure which needs explanation2 and  
their name expresses their              

comparatively small extension4 ,they    
differ from barrier-reefs in not  lying 
so far from the shore1 and in not having
 within a broad channel  of deep water4 
,reefs also occur around submerged banks
 of sediment and  of worn-down rock2 and
 others are scattered quite irregularly 
where the  sea is very shallow2 these in
 most respects are allied to those of   
the  fringing class1 but they are of    
comparatively little interest4    ,i    
have given a separate chapter to each of
 the above classes1 and have  described 
some one reef or island1 on which ,i    
possessed most  information1 as typical2
 and have afterwards compared it with   
others of  a like kind4 ,although this  
classification is useful from being     
obvious1  and from including most of the
 coral-reefs existing in the open sea1  
it  admits of a more fundamental        
division into barrier and atoll-formed  
reefs on the one hand1 where there is a 
great apparent difficulty with  respect 
to the foundation on which they must    

first have grown2 and into              
fringing-reefs on the other1 where1     
owing to the nature of the slope of  the
 adjoining land1 there is no such       
difficulty4 ,the two blue tints and  the
 red colour 7replaced by numbers in this
 edition47 on the map 7,plate  ,,iii471 
represent this main division1 as        
explained in the beginning of  the last 
chapter4 ,in the ,appendix1 every       
existing coral-reef1 except  some on the
 coast of ,brazil not included in the   
map1 is briefly  described in           
geographical order1 as far as ,i        
possessed information2 and  any         
particular spot may be found by         
consulting the ,index4    ,several      
theories have been advanced to explain  
the origin of atolls or  lagoon-islands1
 but scarcely one to account for        
barrier-reefs4 ,from the  limited depths
 at which reef-building polypifers can  
flourish1 taken  into consideration with
 certain other circumstances1 we are    
compelled  to conclude1 as it will be   

seen1 that both in atolls and           
barrier-reefs1  the foundation on which 
the coral was primarily attached1 has   
subsided2  and that during this downward
 movement1 the reefs have grown upwards4
  ,this conclusion1 it will be further  
seen1 explains most satisfactorily  the 
outline and general form of atolls and  
barrier-reefs1 and likewise  certain    
peculiarities in their structure4 ,the  
distribution1 also1 of  the different   
kinds of coral-reefs1 and their position
 with relation to  the areas of recent  
elevation1 and to the points subject to 
volcanic  eruptions1 fully accord with  
this theory of their origin4#b     #b ,a
 brief account of my views on coral     
formations1 now published in   my       
,journal of ,researches1 was read ,may  
#cast1 #ahcg1 before the   ,geological  
,society1 and an abstract has appeared  
in the ,proceedings4          ,,chapter 
,i4    ,,atolls ,,or ,,lagoon-,,islands4
    ,,section ,i4--,,keeling ,,atoll4   
,corals on the outer margin4--,zone of  

,nullipor4--,exterior                   
reef4--,islets4--,coral-conglomerate4--,
lagoon4--,calcareous sediment4--,scari  
and ,holuthuri subsisting on            
corals4--,changes in the condition of   
the  reefs and islets4--,probable       
subsidence of the atoll4--,future state 
of the  lagoon4      ,illustration      
,a4--,level of the sea at low water3    
where the letter ,a is placed1 the      
depth is twenty-five fathoms1 and the   
distance rather more than one  hundred  
and fifty yards from the edge of the    
reef4    ,b4--,outer edge of that flat  
part of the reef1 which dries at low    
water3  the edge either consists of a   
convex mound1 as represented1 or of     
rugged points1 like those a little      
farther seaward1 beneath the water4     
,c4--,a flat of coral-rock1 covered at  
high water4    ,d4--,a low projecting   
ledge of brecciated coral-rock washed by
 the waves  at high water4    ,e4--,a   
slope of loose fragments1 reached by the
 sea only during gales3  the upper part1

 which is from six to twelve feet high1 
is clothed with  vegetation4 ,the       
surface of the islet gently slopes to   
the lagoon4    ,f4--,level of the lagoon
 at low water4    ,keeling or ,cocos    
atoll is situated in the ,indian ,ocean1
 in #ab #e ,s41  and longitude #ij #ee  
,e43 a reduced chart of it was made from
 the  survey of ,captain ,fitzroy and   
the ,officers of ,h4,m4,s4 8,beagle10 is
 given  in ,plate ,i41 ,figure #aj4 ,the
 greatest width of this atoll is nine   
miles  and a half4 ,its structure is in 
most respects characteristic of the     
class to which it belongs1 with the     
exception of the shallowness of the     
lagoon4 ,the accompanying woodcut       
represents a vertical section1  supposed
 to be drawn at low water from the outer
 coast across one of  the low islets    
7one being taken of average dimensions7 
to within the  lagoon4    ,the section  
is true to the scale in a horizontal    
line1 but it could not  be made so in a 
vertical one1 as the average greatest   

height of the  land is only between six 
and twelve feet above high-water mark4  
,i will describe the section1 commencing
 with the outer margin4 ,i must  first  
observe that the reef-building          
polypifers1 not being tidal  animals1   
require to be constantly submerged or   
washed by the breakers4  ,i was assured 
by ,mr4 ,liesk1 a very intelligent      
resident on these  islands1 as well as  
by some chiefs at ,tahiti 7,otaheite71  
that an  exposure to the rays of the sun
 for a very short time invariably causes
  their destruction4 ,hence it is       
possible only under the most favourable 
circumstances1 afforded by an unusually 
low tide and smooth water1 to  reach the
 outer margin1 where the coral is alive4
 ,i succeeded only  twice in gaining    
this part1 and found it almost entirely 
composed of a  living ,porites1 which   
forms great irregularly rounded masses  
7like  those of an ,astra1 but larger7  
from four to eight feet broad1 and      
little less in thickness4 ,these mounds 

are separated from each other by  narrow
 crooked channels1 about six feet deep1 
most of which intersect  the line of    
reef at right angles4 ,on the furthest  
mound1 which ,i was  able to reach by   
the aid of a leaping-pole1 and over     
which the sea  broke with some violence1
 although the day was quite calm and the
 tide  low1 the polypifers in the       
uppermost cells were all dead1 but      
between  three and four inches lower    
down on its side they were living1 and  
formed a projecting border round the    
upper and dead surface4 ,the coral      
being thus checked in its upward growth1
 extends laterally1 and hence  most of  
the masses1 especially those a little   
further inwards1 had  broad flat dead   
summits4 ,on the other hand ,i could    
see1 during the  recoil of the breakers1
 that a few yards further seaward1 the  
whole  convex surface of the ,porites   
was alive2 so that the point where we   
were standing was almost on the exact   
upward and shoreward limit of  existence

 of those corals which form the outer   
margin of the reef4 ,we  shall presently
 see that there are other organic       
productions1 fitted to  bear a somewhat 
longer exposure to the air and sun4     
,next1 but much inferior in importance  
to the ,porites1 is the ,millepora      
complanata4#a ,it grows in thick        
vertical plates1 intersecting each      
other at various angles1 and forms an   
exceedingly strong honeycombed  mass1   
which generally affects a circular form1
 the marginal plates  alone being alive4
 ,between these plates and in the       
protected crevices  on the reef1 a      
multitude of branching zoophytes and    
other productions  flourish1 but the    
,porites and ,millepora alone seem able 
to resist the  fury of the breakers on  
its upper and outer edge3 at the depth  
of a few  fathoms other kinds of stony  
corals live4 ,mr4 ,liesk1 who was       
intimately  acquainted with every part  
of this reef1 and likewise with that of 
,north ,keeling atoll1 assured me that  

these corals invariably compose  the    
outer margin4 ,the lagoon is inhabited  
by quite a distinct set of  corals1     
generally brittle and thinly branched2  
but a ,porites1  apparently of the same 
species with that on the outside1 is    
found  there1 although it does not seem 
to thrive1 and certainly does not       
attain the thousandth part in bulk of   
the masses opposed to the  breakers4    
#a ,this ,millepora 7,palmipora of      
,blainville71 as well as the ,m4        
alcicornis1 possesses the singular      
property of stinging the skin   where it
 is delicate1 as on the face and arm4   
,the woodcut shows the form of the      
bottom off the reef3 the water  deepens 
for a space between one and two hundred 
yards wide1 very  gradually to          
twenty-five fathoms 7,a in section71    
beyond which the  sides plunge into the 
unfathomable ocean at an angle of #de4b 
,to the  depth of ten or twelve fathoms 
the bottom is exceedingly rugged1 and   
seems formed of great masses of living  

coral1 similar to those on the  margin4 
,the arming of the lead here invariably 
came up quite clean1 but  deeply        
indented1 and chains and anchors which  
were lowered1 in the  hopes of tearing  
up the coral1 were broken4 ,many small  
fragments1  however1 of ,millepora      
alcicornis were brought up2 and on the  
arming  from an eight-fathom cast1 there
 was a perfect impression of an ,astra1 
apparently alive4 ,i examined the rolled
 fragments cast on the beach  during    
gales1 in order further to ascertain    
what corals grew outside  the reef4 ,the
 fragments consisted of many kinds1 of  
which the ,porites  already mentioned   
and a ,madrepora1 apparently the ,m4    
corymbosa1 were  the most abundant4 ,as 
,i searched in vain in the hollows on   
the reef and  in the lagoon1 for a      
living specimen of this ,madrepore1 ,i  
conclude that  it is confined to a zone 
outside1 and beneath the surface1 where 
it  must be very abundant4 ,fragments of
 the ,millepora alcicornis and of  an   

,astra were also numerous2 the former is
 found1 but not in  proportionate       
numbers1 in the hollows on the reef2 but
 the ,astra ,i did  not see living4     
,hence we may infer1 that these are the 
kinds of coral  which form the rugged   
sloping surface 7represented in the     
woodcut by an  uneven line71 round and  
beneath the external margin4 ,between   
twelve and  twenty fathoms the arming   
came up an equal number of times        
smoothed  with sand1 and indented with  
coral3 an anchor and lead were lost at  
the  respective depths of thirteen and  
sixteen fathoms4 ,out of twenty-five    
soundings taken at a greater depth than 
twenty fathoms1 every one  showed that  
the bottom was covered with sand2       
whereas1 at a less depth  than twelve   
fathoms1 every sounding showed that it  
was exceedingly  rugged1 and free from  
all extraneous particles4 ,two soundings
 were  obtained at the depth of #cfj    
fathoms1 and several between two hundred
  and three hundred fathoms4 ,the sand  

brought up from these depths  consisted 
of finely triturated fragments of stony 
zoophytes1 but not1  as far as ,i could 
distinguish1 of a particle of any       
lamelliform genus3  fragments of shells 
were rare4     #b ,the soundings from   
which this section is laid down were    
taken with   great care by ,captain     
,fitzroy himself4 ,he used a bell-shaped
 lead1   having a diameter of four      
inches1 and the armings each time were  
cut   off and brought on board for me to
 examine4 ,the arming is a   preparation
 of tallow1 placed in the concavity at  
the bottom of the   lead4 ,sand1 and    
even small fragments of rock1 will      
adhere to it2 and   if the bottom be of 
rock it brings up an exact impression of
 its   surface4      ,at a distance of  
#b1bjj yards from the breakers1 ,captain
 ,fitzroy found  no bottom with a line  
of #g1bjj feet in length2 hence the     
submarine  slope of this coral formation
 is steeper than that of any volcanic   
cone4 ,off the mouth of the lagoon1 and 

likewise off the northern point  of the 
atoll1 where the currents act violently1
 the inclination1 owing  to the         
accumulation of sediment1 is less4 ,as  
the arming of the lead  from all the    
greater depths showed a smooth sandy    
bottom1 ,i at first  concluded that the 
whole consisted of a vast conical pile  
of calcareous  sand1 but the sudden     
increase of depth at some points1 and   
the  circumstance of the line having    
been cut1 as if rubbed1 when between    
five hundred and six hundred fathoms    
were out1 indicate the probable         
existence of submarine cliffs4    ,on   
the margin of the reef1 close within the
 line where the upper  surface of the   
,porites and of the ,millepora is dead1 
three species of  ,nullipora flourish4  
,one grows in thin sheets1 like a lichen
 on old  trees2 the second in stony     
knobs1 as thick as a man's finger1      
radiating  from a common centre2 and the
 third1 which is less common1 in a      
moss-like reticulation of thin1 but     

perfectly rigid branches4#c ,the  three 
species occur either separately or      
mingled together2 and they  form by     
their successive growth a layer two or  
three feet in thickness1  which in some 
cases is hard1 but where formed of the  
lichen-like kind1  readily yields an    
impression to the hammer3 the surface is
 of a reddish  colour4 ,these ,nullipor1
 although able to exist above the limit 
of true  corals1 seem to require to be  
bathed during the greater part of each  
tide by breaking water1 for they are not
 found in any abundance in the          
protected hollows on the back part of   
the reef1 where they might be  immersed 
either during the whole or an equal     
proportional time of each  tide4 ,it is 
remarkable that organic productions of  
such extreme  simplicity1 for the       
,nullipor undoubtedly belong to one of  
the lowest  classes of the vegetable    
kingdom1 should be limited to a zone so 
peculiarly circumstanced4 ,hence the    
layer composed by their growth  merely  

fringes the reef for a space of about   
twenty yards in width1  either under the
 form of separate mammillated           
projections1 where the  outer masses of 
coral are separate1 or1 more commonly1  
where the corals  are united into a     
solid margin1 as a continuous smooth    
convex mound  7,b in woodcut71 like an  
artificial breakwater4 ,both the mound  
and  mammillated projections stand about
 three feet higher than any other  part 
of the reef1 by which term ,i do not    
include the islets1 formed by  the      
accumulation of rolled fragments4 ,we   
shall hereafter see that other  coral   
reefs are protected by a similar thick  
growth of ,nullipor on the  outer       
margin1 the part most exposed to the    
breakers1 and this must  effectually aid
 in preserving it from being worn down4 
#c ,this last species is of a beautiful 
bright peach-blossom colour4   ,its     
branches are about as thick as          
crow-quills2 they are slightly          
flattened and knobbed at the            

extremities4 ,the extremities only are  
alive and brightly coloured4 ,the two   
other species are of a dirty            
purplish-white4 ,the second species is  
extremely hard2 its short   knob-like   
branches are cylindrical1 and do not    
grow thicker at their   extremities4    
,the woodcut represents a section across
 one of the islets on the reef1  but if 
all that part which is above the level  
of ,c were removed1 the  section would  
be that of a simple reef1 as it occurs  
where no islet has  been formed4 ,it is 
this reef which essentially forms the   
atoll4 ,it is a  ring1 enclosing the    
lagoon on all sides except at the       
northern end1  where there are two open 
spaces1 through one of which ships can  
enter4  ,the reef varies in width from  
two hundred and fifty to five hundred   
yards1 its surface is level1 or very    
slightly inclined towards the  lagoon1  
and at high tide the sea breaks entirely
 over it3 the water at  low tide thrown 
by the breakers on the reef1 is carried 

by the many  narrow and shoal gullies or
 channels on its surface1 into the      
lagoon3 a  return stream sets out of the
 lagoon through the main entrance4 ,the 
most frequent coral in the hollows on   
the reef is ,pocillopora  verrucosa1    
which grows in short sinuous plates1 or 
branches1 and when  alive is of a       
beautiful pale lake-red3 a ,madrepora1  
closely allied or  identical with ,m4   
pocillifera1 is also common4 ,as soon as
 an islet is  formed1 and the waves are 
prevented breaking entirely over the    
reef1  the channels and hollows in it   
become filled up with cemented          
fragments1 and its surface is converted 
into a hard smooth floor 7,c  of        
woodcut71 like an artificial one of     
freestone4 ,this flat surface  varies in
 width from one hundred to two hundred1 
or even three hundred  yards1 and is    
strewed with a few large fragments of   
coral torn up  during gales3 it is      
uncovered only at low water4 ,i could   
with  difficulty1 and only by the aid of

 a chisel1 procure chips of rock from   
its surface1 and therefore could not    
ascertain how much of it is formed  by  
the aggregation of detritus1 and how    
much by the outward growth of  mounds of
 corals1 similar to those now living on 
the margin4 ,nothing  can be more       
singular than the appearance at low tide
 of this 8flat0 of  naked stone1        
especially where it is externally       
bounded by the smooth  convex mound of  
,nullipor1 appearing like a breakwater  
built to resist  the waves1 which are   
constantly throwing over it sheets of   
foaming  water4 ,the characteristic     
appearance of this 8flat0 is shown in   
the  foregoing woodcut of ,whitsunday   
atoll4    ,the islets on the reef are   
first formed between two hundred and    
three  hundred yards from its outer     
edge1 through the accumulation of a pile
  of fragments1 thrown together by some 
unusually strong gale4 ,their  ordinary 
width is under a quarter of a mile1 and 
their length varies  from a few yards to

 several miles4 ,those on the south-east
 and windward  side of the atoll1       
increase solely by the addition of      
fragments on  their outer side2 hence   
the loose blocks of coral1 of which     
their  surface is composed1 as well as  
the shells mingled with them1 almost    
exclusively consist of those kinds which
 live on the outer coast4 ,the  highest 
part of the islets 7excepting hillocks  
of blown sand1 some of  which are thirty
 feet high71 is close to the outer beach
 7,e of the  woodcut71 and averages from
 six to ten feet above ordinary         
high-water  mark4 ,from the outer beach 
the surface slopes gently to the shores 
of  the lagoon1 which no doubt has been 
caused by the breakers the further  they
 have rolled over the reef1 having had  
less power to throw up  fragments4 ,the 
little waves of the lagoon heap up sand 
and fragments of  thinly-branched corals
 on the inner side of the islets on the 
leeward  side of the atoll2 and these   
islets are broader than those to        

windward1  some being even eight hundred
 yards in width2 but the land thus added
  is very low4 ,the fragments beneath   
the surface are cemented into a  solid  
mass1 which is exposed as a ledge 7,d of
 the woodcut71  projecting some yards in
 front of the outer shore and from two  
to four  feet high4 ,this ledge is just 
reached by the waves at ordinary        
high-water3 it extends in front of all  
the islets1 and everywhere has a        
water-worn and scooped appearance4 ,the 
fragments of coral which are            
occasionally cast on the 8flat0 are     
during gales of unusual violence  swept 
together on the beach1 where the waves  
each day at high-water  tend to remove  
and gradually wear them down2 but the   
lower fragments  having become firmly   
cemented together by the percolation of 
calcareous  matter1 resist the daily    
tides longer1 and hence project as a    
ledge4  ,the cemented mass is generally 
of a white colour1 but in some few parts
  reddish from ferruginous matter2 it is

 very hard1 and is sonorous under  the  
hammer2 it is obscurely divided by      
seams1 dipping at a small angle         
seaward2 it consists of fragments of the
 corals which grow on the outer  margin1
 some quite and others partially        
rounded1 some small and others  between 
two and three feet across2 and of masses
 of previously formed  conglomerate1    
torn up1 rounded1 and re-cemented2 or it
 consists of a  calcareous sandstone1   
entirely composed of rounded particles1 
generally  almost blended together1 of  
shells1 corals1 the spines of echini1   
and  other such organic bodies2 rocks1  
of this latter kind1 occur on many      
shores1 where there are no coral reefs4 
,the structure of the coral in  the     
conglomerate has generally been much    
obscured by the infiltration  of        
spathose calcareous matter2 and ,i      
collected a very interesting  series1   
beginning with fragments of unaltered   
coral1 and ending with  others1 where it
 was impossible to discover with the    

naked eye any  trace of organic         
structure4 ,in some specimens ,i was    
unable1 even with  the aid of a lens1   
and by wetting them1 to distinguish the 
boundaries  of the altered coral and    
spathose limestone4 ,many even of the   
blocks of  coral lying loose on the     
beach1 had their central parts altered  
and  infiltrated4    ,the lagoon alone  
remains to be described2 it is much     
shallower than  that of most atolls of  
considerable size4 ,the southern part is
 almost  filled up with banks of mud and
 fields of coral1 both dead and alive1  
but there are considerable spaces1      
between three and four fathoms1 and     
smaller basins1 from eight to ten       
fathoms deep4 ,probably about half its  
area consists of sediment1 and half of  
coral-reefs4 ,the corals  composing     
these reefs have a very different aspect
 from those on the  outside2 they are   
very numerous in kind1 and most of them 
are thinly  branched4 ,meandrina1       
however1 lives in the lagoon1 and great 

rounded  masses of this coral are       
numerous1 lying quite or almost loose on
 the  bottom4 ,the other commonest kinds
 consist of three closely allied        
species of true ,madrepora in thin      
branches2 of ,seriatapora subulata2  two
 species of ,porites#d with cylindrical 
branches1 one of which forms  circular  
clumps1 with the exterior branches only 
alive2 and lastly1 a  coral something   
like an ,explanaria1 but with stars on  
both surfaces1  growing in thin1        
brittle1 stony1 foliaceous expansions1  
especially in  the deeper basins of the 
lagoon4 ,the reefs on which these corals
 grow  are very irregular in form1 are  
full of cavities1 and have not a solid  
flat surface of dead rock1 like that    
surrounding the lagoon2 nor can  they be
 nearly so hard1 for the inhabitants    
made with crowbars a  channel of        
considerable length through these reefs1
 in which a  schooner1 built on the     
,s4,e4 islet1 was floated out4 ,it is a 
very  interesting circumstance1 pointed 

out to us by ,mr4 ,liesk1 that this     
channel1 although made less than ten    
years before our visit1 was then1  as we
 saw1 almost choked up with living      
coral1 so that fresh  excavations would 
be absolutely necessary to allow another
 vessel to  pass through it4     #d     
,this ,porites has somewhat the habit of
 ,p4 clavaria1 but the   branches are   
not knobbed at their ends4 ,when alive  
it is of a yellow   colour1 but after   
having been washed in fresh water and   
placed to dry1   a jet-black slimy      
substance exuded from the entire        
surface1 so that   the specimen now     
appears as if it had been dipped in ink4
      ,the sediment from the deepest    
parts in the lagoon1 when wet1 appeared 
chalky1 but when dry1 like very fine    
sand4 ,large soft banks of similar1  but
 even finer grained mud1 occur on the   
,s4,e4 shore of the lagoon1  affording a
 thick growth of a ,fucus1 on which     
turtle feed3 this mud1  although        
discoloured by vegetable matter1 appears

 from its entire  solution in acids to  
be purely calcareous4 ,i have seen in   
the ,museum of  the ,geological         
,society1 a similar but more remarkable 
substance1  brought by ,lieutenant      
,nelson from the reefs of ,bermuda1     
which1 when  shown to several           
experienced geologists1 was mistaken by 
them for true  chalk4 ,on the outside of
 the reef much sediment must be formed  
by the  action of the surf on the rolled
 fragments of coral2 but in the calm    
waters of the lagoon1 this can take     
place only in a small degree4 ,there    
are1 however1 other and unexpected      
agents at work here3 large shoals of    
two species of ,scarus1 one inhabiting  
the surf outside the reef and the  other
 the lagoon1 subsist entirely1 as ,i was
 assured by ,mr4 ,liesk1 the            
intelligent resident before referred to1
 by browsing on the living  polypifers4 
,i opened several of these fish1 which  
are very numerous and  of considerable  
size1 and ,i found their intestines     

distended by small  pieces of coral1 and
 finely ground calcareous matter4 ,this 
must daily  pass from them as the finest
 sediment2 much also must be produced by
  the infinitely numerous vermiform and 
molluscous animals1 which make  cavities
 in almost every block of coral4 ,dr4   
,j4 ,allan1 of ,forres1 who  has enjoyed
 the best means of observation1 informs 
me in a letter that  the ,holothuri 7a  
family of ,radiata7 subsist on living   
coral2 and the  singular structure of   
bone within the anterior extremity of   
their  bodies1 certainly appears well   
adapted for this purpose4 ,the number of
  the species of ,holothuria1 and of the
 individuals which swarm on every  part 
of these coral-reefs1 is extraordinarily
 great2 and many shiploads  are annually
 freighted1 as is well-known1 for ,china
 with the trepang1  which is a species  
of this genus4 ,the amount of coral     
yearly consumed1  and ground down into  
the finest mud1 by these several        
creatures1 and  probably by many other  

kinds1 must be immense4 ,these facts    
are1  however1 of more importance in    
another point of view1 as showing us    
that there are living checks to the     
growth of coral-reefs1 and that the     
almost universal law of 8consumed and be
 consumed10 holds good even  with the   
polypifers forming those massive        
bulwarks1 which are able to  withstand  
the force of the open ocean4            
,considering that ,keeling atoll1 like  
other coral formations1 has been        
entirely formed by the growth of organic
 beings1 and the accumulation  of their 
detritus1 one is naturally led to       
inquire how long it has  continued1 and 
how long it is likely to continue1 in   
its present state4  ,mr4 ,liesk informed
 me that he had seen an old chart in    
which the  present long island on the   
,s4,e4 side was divided by several      
channels  into as many islets2 and he   
assures me that the channels can still  
be  distinguished by the smaller size of
 the trees on them4 ,on several  islets1

 also1 ,i observed that only young      
cocoa-nut trees were growing  on the    
extremities2 and that older and taller  
trees rose in regular  succession behind
 them2 which shows that these islets    
have very lately  increased in length4  
,in the upper and south-eastern part of 
the lagoon1  ,i was much surprised by   
finding an irregular field of at least a
 mile  square of branching corals1 still
 upright1 but entirely dead4 ,they      
consisted of the species already        
mentioned2 they were of a brown  colour1
 and so rotten1 that in trying to stand 
on them ,i sank halfway  up the leg1 as 
if through decayed brushwood4 ,the tops 
of the branches  were barely covered by 
water at the time of lowest tide4       
,several facts  having led me to        
disbelieve in any elevation of the whole
 atoll1 ,i was  at first unable to      
imagine what cause could have killed so 
large a  field of coral4 ,upon          
reflection1 however1 it appeared to me  
that the  closing up of the             

above-mentioned channels would be a     
sufficient cause2  for before this1 a   
strong breeze by forcing water through  
them into the  head of the lagoon1 would
 tend to raise its level4 ,but now this 
cannot  happen1 and the inhabitants     
observe that the tide rises to a less   
height1 during a high ,s4,e4 wind1 at   
the head than at the mouth of the       
lagoon4 ,the corals1 which1 under the   
former condition of things1 had         
attained the utmost possible limit of   
upward growth1 would thus  occasionally 
be exposed for a short time to the sun1 
and be killed4    ,besides the increase 
of dry land1 indicated by the foregoing 
facts1 the  exterior solid reef appears 
to have grown outwards4 ,on the western 
side  of the atoll1 the 8flat0 lying    
between the margin of the reef and the  
beach1 is very wide2 and in front of the
 regular beach with its  conglomerate   
basis1 there is1 in most parts1 a bed of
 sand and loose  fragments with trees   
growing out of it1 which apparently is  

not reached  even by the spray at high  
water4 ,it is evident some change has   
taken  place since the waves formed the 
inner beach2 that they formerly beat    
against it with violence was evident1   
from a remarkably thick and  water-worn 
point of conglomerate at one spot1 now  
protected by  vegetation and a bank of  
sand2 that they beat against it in the  
same  peculiar manner in which the swell
 from windward now obliquely curls      
round the margin of the reef1 was       
evident from the conglomerate having    
been worn into a point projecting from  
the beach in a similarly oblique        
manner4 ,this retreat in the line of    
action of the breakers might  result1   
either from the surface of the reef in  
front of the islets  having been        
submerged at one time1 and afterward    
having grown upwards1  or from the      
mounds of coral on the margin having    
continued to grow  outwards4 ,that an   
outward growth of this part is in       
process1 can hardly  be doubted from the

 fact already mentioned of the mounds of
 ,porites  with their summits apparently
 lately killed1 and their sides only    
three  or four inches lower down        
thickened by a fresh layer of living    
coral4  ,but there is a difficulty on   
this supposition which ,i must not pass 
over4 ,if the whole1 or a large part of 
the 8flat10 had been formed by  the     
outward growth of the margin1 each      
successive margin would  naturally have 
been coated by the ,nullipor1 and so    
much of the surface  would have been of 
equal height with the existing zone of  
living  ,nullipor3 this is not the case1
 as may be seen in the woodcut4 ,it is1 
however1 evident from the abraded state 
of the 8flat10 with its  original       
inequalities filled up1 that its surface
 has been much  modified2 and it is     
possible that the hinder portions of the
 zone of  ,nullipor1 perishing as the   
reef grows outwards1 might be worn down 
by  the surf4 ,if this has not taken    
place1 the reef can in no part have     

increased outwards in breadth since its 
formation1 or at least since  the       
,nullipor formed the convex mound on its
 margin2 for the zone thus  formed1 and 
which stands between two and three feet 
above the other  parts of the reef1 is  
nowhere much above twenty yards in      
width4    ,thus far we have considered  
facts1 which indicate1 with more or less
  probability1 the increase of the atoll
 in its different parts3 there  are     
others having an opposite tendency4 ,on 
the south-east side1  ,lieutenant       
,sulivan1 to whose kindness ,i am       
indebted for many  interesting          
observations1 found the conglomerate    
projecting on the reef  nearly fifty    
yards in front of the beach3 we may     
infer from what we see  in all other    
parts of the atoll1 that the            
conglomerate was not  originally so much
 exposed1 but formed the base of an     
islet1 the front  and upper part of     
which has since been swept away4 ,the   
degree to which  the conglomerate1 round

 nearly the whole atoll1 has been       
scooped1  broken up1 and the fragments  
cast on the beach1 is certainly very    
surprising1 even on the view that it is 
the office of occasional gales  to pile 
up fragments1 and of the daily tides to 
wear them away4 ,on the  western side1  
also1 of the atoll1 where ,i have       
described a bed of sand  and fragments  
with trees growing out of it1 in front  
of an old beach1  it struck both        
,lieutenant ,sulivan and myself1 from   
the manner in which  the trees were     
being washed down1 that the surf had    
lately recommenced  an attack on this   
line of coast4 ,appearances indicating a
 slight  encroachment of the water on   
the land1 are plainer within the lagoon3
 ,i  noticed in several places1 both on 
its windward and leeward shores1 old    
cocoa-nut trees falling with their roots
 undermined1 and the rotten  stumps of  
others on the beach1 where the          
inhabitants assured us the  cocoa-nut   
could not now grow4 ,captain ,fitzroy   

pointed out to me1 near  the settlement1
 the foundation posts of a shed1 now    
washed by every  tide1 but which the    
inhabitants stated1 had seven years     
before stood  above high watermark4 ,in 
the calm waters of the lagoon1 directly 
connected with a great1 and therefore   
stable ocean1 it seems very  improbable 
that a change in the currents1          
sufficiently great to cause  the water  
to eat into the land on all sides1      
should have taken place  within a       
limited period4 ,from these             
considerations ,i inferred1 that        
probably the atoll had lately subsided  
to a small amount2 and this  inference  
was strengthened by the circumstance1   
that in #ahcd1 two years  before our    
visit1 the island had been shaken by a  
severe earthquake1  and by two slighter 
ones during the ten previous years4 ,if1
 during  these subterranean             
disturbances1 the atoll did subside1 the
 downward  movement must have been very 
small1 as we must conclude from the     

fields  of dead coral still lipping the 
surface of the lagoon1 and from the     
breakers on the western shore not having
 yet regained the line of their  former 
action4 ,the subsidence must1 also1 have
 been preceded by a long  period of     
rest1 during which the islets extended  
to their present size1  and the living  
margin of the reef grew either upwards1 
or as ,i believe  outwards1 to its      
present distance from the beach4        
,whether this view be correct or not1   
the above facts are worthy of           
attention1 as showing how severe a      
struggle is in progress on these low    
coral formations between the two nicely 
balanced powers of land and  water4     
,with respect to the future state of    
,keeling atoll1 if left  undisturbed1 we
 can see that the islets may still      
extend in length2 but  as they cannot   
resist the surf until broken by rolling 
over a wide  space1 their increase in   
breadth must depend on the increasing   
breadth  of the reef2 and this must be  

limited by the steepness of the         
submarine  flanks1 which can be added to
 only by sediment derived from the wear 
and tear of the coral4 ,from the rapid  
growth of the coral in the  channel cut 
for the schooner1 and from the several  
agents at work in  producing fine       
sediment1 it might be thought that the  
lagoon would  necessarily become quickly
 filled up4 ,some of this sediment1     
however1  is transported into the open  
sea1 as appears from the soundings off  
the  mouth of the lagoon1 instead of    
being deposited within it4 ,the         
deposition1 moreover1 of sediment1      
checks the growth of coral-reefs1 so    
that these two agencies cannot act      
together with full effect in filling  it
 up4 ,we know so little of the habits of
 the many different species of  corals1 
which form the lagoon-reefs1 that we    
have no more reasons for  supposing that
 their whole surface would grow up as   
quickly as the  coral did in the        
schooner-channel1 than for supposing    

that the whole  surface of a peat-moss  
would increase as quickly as parts are  
known to  do in holes1 where the peat   
has been cut away4 ,these agencies1     
nevertheless1 tend to fill up the       
lagoon2 but in proportion as it  becomes
 shallower1 so must the polypifers be   
subject to many injurious  agencies1    
such as impure water and loss of food4  
,for instance1 ,mr4  ,liesk informed me1
 that some years before our visit       
unusually heavy  rain killed nearly all 
the fish in the lagoon1 and probably the
 same  cause would likewise injure the  
corals4 ,the reefs also1 it must be     
remembered1 cannot possibly rise above  
the level of the lowest  spring-tide1 so
 that the final conversion of the lagoon
 into land must  be due to the          
accumulation of sediment2 and in the    
midst of the clear  water of the ocean1 
and with no surrounding high land1 this 
process  must be exceedingly slow4      
,,section ,,ii4--,,general ,,description
 ,,of ,,atolls4    ,general form and    

size of atolls1 their reefs and         
islets4--,external  slope4-- ,zone of   
,nullipor4--,conglomerate4--,depth of   
lagoons4--,sediment4--,reefs submerged  
wholly or in part4--,breaches in the    
reef4--,ledge-formed shores round       
certain lagoons4--,conversion of lagoons
  into land4      ,i will here give a   
sketch of the general form and structure
 of the many  atolls and atoll-formed   
reefs which occur in the ,pacific and   
,indian  ,oceans1 comparing them with   
,keeling atoll4 ,the ,maldiva atolls and
 the  ,great ,chagos ,bank differ in so 
many respects1 that ,i shall devote to  
them1 besides occasional references1 a  
third section of this chapter4  ,keeling
 atoll may be considered as of moderate 
dimensions and of  regular form4 ,of the
 thirty-two islands surveyed by ,captain
 ,beechey in  the ,low ,archipelago1 the
 longest was found to be thirty miles1  
and the  shortest less than a mile2 but 
,vliegen atoll1 situated in another part
  of the same group1 appears to be sixty

 miles long and twenty broad4  ,most of 
the atolls in this group are of an      
elongated form2 thus ,bow  ,island is   
thirty miles in length1 and on an       
average only six in width  7,see ,figure
 #d1 ,plate ,i471 and ,clermont ,tonnere
 has nearly the same  proportions4 ,in  
the ,marshall ,archipelago 7the ,ralick 
and ,radack group  of ,kotzebue7 several
 of the atolls are more than thirty     
miles in  length1 and ,rimsky ,korsacoff
 is fifty-four long1 and twenty wide1 at
  the broadest part of its irregular    
outline4 ,most of the atolls in the     
,maldiva ,archipelago are of great size1
 one of them 7which1 however1  bears a  
double name7 measured in a medial and   
slightly curved line1 is  no less than  
eighty-eight geographical miles long1   
its greatest width  being under twenty1 
and its least only nine and a half      
miles4 ,some  atolls have spurs         
projecting from them2 and in the        
,marshall group there  are atolls united
 together by linear reefs1 for instance 

,menchikoff  ,island 7,see ,figure #c1  
,plate ,,ii471 which is sixty miles in  
length1 and  consists of three loops    
tied together4 ,in far the greater      
number of  cases an atoll consists of a 
simple elongated ring1 with its outline 
moderately regular4    ,the average     
width of the annular wreath may be taken
 as about a quarter  of a mile4 ,captain
 ,beechey#e says that in the atolls of  
the ,low  ,archipelago it exceeded in no
 instance half a mile4 ,the description 
given of the structure and proportional 
dimensions of the reef and  islets of   
,keeling atoll1 appears to apply        
perfectly to nearly all the  atolls in  
the ,pacific and ,indian ,oceans4 ,the  
islets are first formed  some way back  
either on the projecting points of the  
reef1 especially  if its form be        
angular1 or on the sides of the main    
entrances into the  lagoon--that is in  
both cases1 on points where the breakers
 can act  during gales of wind in       
somewhat different directions1 so that  

the  matter thrown up from one side may 
accumulate against that before  thrown  
up from another4 ,in ,lutk's chart of   
the ,caroline atolls1 we see  many      
instances of the former case2 and the   
occurrence of islets1 as if  placed for 
beacons1 on the points where there is a 
gateway or breach  through the reef1 has
 been noticed by several authors4 ,there
 are some  atoll-formed reefs1 rising to
 the surface of the sea and partly dry  
at  low water1 on which from some cause 
islets have never been formed2 and      
there are others on which they have been
 formed1 but have subsequently  been    
worn away4 ,in atolls of small          
dimensions the islets frequently  become
 united into a single horse-shoe or     
ring-formed strip2 but ,diego  ,garcia1 
although an atoll of considerable size1 
being thirteen miles  and a half in     
length1 has its lagoon entirely         
surrounded1 except at the  northern end1
 by a belt of land1 on an average a     
third of a mile in  width4 ,to show how 

small the total area of the annular reef
 and the  land is in islands of this    
class1 ,i may quote a remark from the   
voyage  of ,lutk1 namely1 that if the   
forty-three rings1 or atolls1 in the    
,caroline ,archipelago1 were put one    
within another1 and over a steeple  in  
the centre of ,st4 ,petersburg1 the     
whole world would not cover that  city  
and its suburbs4     #e ,beechey's      
8,voyage to the ,pacific and ,beering's 
,straits10 chapter   viii4      ,the    
form of the bottom off ,keeling atoll1  
which gradually slopes to  about twenty 
fathoms at the distance of between one  
and two hundred  yards from the edge of 
the reef1 and then plunges at an angle  
of #de  into unfathomable depths1 is    
exactly the same#f with that of the     
sections of the atolls in the ,low      
,archipelago given by ,captain ,beechey4
  ,the nature1 however1 of the bottom   
seems to differ1 for this officer#g     
informs me that all the soundings1 even 
the deepest1 were on coral1 but  he does

 not know whether dead or alive4 ,the   
slope round ,christmas atoll  7,lat4 #a 
#d ,n41 #aeg #de ,w471 described by     
,cook1#h is considerably  less1 at about
 half a mile from the edge of the reef1 
the average depth  was about fourteen   
fathoms on a fine sandy bottom1 and at a
 mile1 only  between twenty and forty   
fathoms4 ,it has no doubt been owing to 
this  gentle slope1 that the strip of   
land surrounding its lagoon1 has        
increased in one part to the            
extraordinary width of three miles2 it  
is  formed of successive ridges of      
broken shells and corals1 like those on 
the beach4 ,i know of no other instance 
of such width in the reef of an  atoll2 
but ,mr4 ,f4,d4 ,bennett informs me that
 the inclination of the  bottom round   
,caroline atoll in the ,pacific1 is like
 that off ,christmas  ,island1 very     
gentle4 ,off the ,maldiva and ,chagos   
atolls1 the inclination  is much more   
abrupt2 thus at ,heawandoo ,pholo1      
,lieutenant ,powell#i  found fifty and  

sixty fathoms close to the edge of the  
reef1 and at #cjj  yards distance there 
was no bottom with a #cjj-yard line4    
,captain  ,moresby informs me1 that at  
#ajj fathoms from the mouth of the      
lagoon of  ,diego ,garcia1 he found no  
bottom with #aej fathoms2 this is the   
more  remarkable1 as the slope is       
generally less abrupt in front of       
channels  through a reef1 owing to the  
accumulation of sediment4 ,at ,egmont   
,island1 also1 at #aej fathoms from the 
reef1 soundings were struck with  #aej  
fathoms4 ,lastly1 at ,cardoo atoll1 only
 sixty yards from the reef1  no bottom  
was obtained1 as ,i am informed by      
,captain ,moresby1 with a  line of #bjj 
fathoms6 ,the currents run with great   
force round these  atolls1 and where    
they are strongest1 the inclination     
appears to be  most abrupt4 ,i am       
informed by the same authority1 that    
wherever  soundings were obtained off   
these islands1 the bottom was invariably
  sandy3 nor was there any reason to    

suspect the existence of submarine      
cliffs1 as there was at ,keeling        
,island4#aj ,here then occurs a         
difficulty2 can sand accumulate on a    
slope1 which1 in some cases1  appears to
 exceed fifty-five degrees8 ,it must be 
observed1 that ,i speak  of slopes where
 soundings were obtained1 and not of    
such cases1 as that  of ,cardoo1 where  
the nature of the bottom is unknown1 and
 where its  inclination must be nearly  
vertical4 ,m4 lie de ,beaumont#aa has   
argued1 and there is no higher authority
 on this subject1 from the  inclination 
at which snow slides down in avalanches1
 that a bed of sand  or mud cannot be   
formed at a greater angle than thirty   
degrees4  ,considering the number of    
soundings on sand1 obtained round the   
,maldiva  and ,chagos atolls1 which     
appears to indicate a greater angle1 and
 the  extreme abruptness of the         
sand-banks in the ,west ,indies1 as will
 be  mentioned in the ,appendix1 ,i must
 conclude that the adhesive property  of

 wet sand counteracts its gravity1 in a 
much greater ratio than has  been       
allowed for by ,m4 lie de ,beaumont4    
,from the facility with which           
calcareous sand becomes agglutinated1 it
 is not necessary to suppose  that the  
bed of loose sand is thick4     #f ,the 
form of the bottom round the ,marshall  
atolls in the ,northern   ,pacific is   
probably similar3 ,kotzebue 78,first    
,voyage10 volume ii41   page #af47 says3
 8,we had at a small distance from the  
reef1 forty   fathoms depth1 which      
increased a little further so much that 
we could   find no bottom407       #g ,i
 must be permitted to express my        
obligation to ,captain ,beechey1   for  
the very kind manner in which he has    
given me information on   several       
points1 and to own the great assistance 
,i have derived from   his excellent    
published work4       #h ,cook's 8,third
 ,voyage10 volume ii41 chapter #aj4     
#i ,this fact is taken from a ,,ms4     
account of these groups lent me by      

,captain ,moresby4 ,see also ,captain   
,moresby's paper on the ,maldiva        
atolls in the 8,geographical ,journal01 
volume v41 page #dja4       #aj ,off    
some of the islands in the ,low         
,archipelago the bottom appears   to    
descend by ledges4 ,off ,elizabeth      
,island1 which1 however1 consists   of  
raised coral1 ,captain ,beechey 7p4 #de1
 quarto edition7 describes   three      
ledges3 the first had an easy slope from
 the beach to a distance   of about     
fifty yards3 the second extended two    
hundred yards with   twenty-five fathoms
 on it1 and then ended abruptly1 like   
the first2   and immediately beyond this
 there was no bottom with two hundred   
fathoms4       #aa 8,mmoires pour servir
  une description ,golog4 de ,france10  
tome   iv41 page #baf4      ,captain    
,beechey has observed1 that the         
submarine slope is much less at  the    
extremities of the more elongated atolls
 in the ,low ,archipelago1  than at     
their sides2 in speaking of ,ducie's    

,island he says#ab the  buttress1 as it 
may be called1 which 8has the most      
powerful enemy 7the  ,s4,w4 swell7 to   
oppose1 is carried out much further1 and
 with less  abruptness than the other40 
,in some cases1 the less inclination of 
a  certain part of the external slope1  
for instance of the northern            
extremities of the two ,keeling atolls1 
is caused by a prevailing  current which
 there accumulates a bed of sand4 ,where
 the water is  perfectly tranquil1 as   
within a lagoon1 the reefs generally    
grow up  perpendicularly1 and sometimes 
even overhang their bases2 on the other 
hand1 on the leeward side of ,mauritius1
 where the water is generally  tranquil1
 although not invariably so1 the reef is
 very gently inclined4  ,hence it       
appears that the exterior angle varies  
much2 nevertheless in  the close        
similarity in form between the sections 
of ,keeling atoll and  of the atolls in 
the ,low ,archipelago1 in the general   
steepness of the  reefs of the ,maldiva 

and ,chagos atolls1 and in the          
perpendicularity of  those rising out of
 water always tranquil1 we may discern  
the effects  of uniform laws2 but from  
the complex action of the surf and      
currents1  on the growing powers of the 
coral and on the deposition of sediment1
  we can by no means follow out all the 
results4     #ab ,beechey's 8,voyage10  
#dto edition1 page #dd4      ,where     
islets have been formed on the reef1    
that part which ,i have  sometimes      
called the 8flat0 and which is partly   
dry at low water1  appears similar in   
every atoll4 ,in the ,marshall group in 
the ,north  ,pacific1 it may be inferred
 from ,chamisso's description1 that the 
reef1  where islets have not been formed
 on it1 slopes gently from the  external
 margin to the shores of the lagoon2    
,flinders states that the  ,australian  
barrier has a similar inclination       
inwards1 and ,i have no  doubt it is of 
general occurrence1 although1 according 
to ,ehrenberg1  the reefs of the ,red   

,sea offer an exception4 ,chamisso      
observes that  8the red colour of the   
reef 7at the ,marshall atolls7 under the
 breakers  is caused by a ,nullipora1   
which covers the stone wherever the     
waves  beat2 and1 under favourable      
circumstances1 assumes a stalactical    
form10--a description perfectly         
applicable to the margin of ,keeling    
atoll4#ac ,although ,chamisso does not  
state that the masses of  ,nullipor form
 points or a mound1 higher than the     
flat1 yet ,i believe  that this is the  
case2 for ,kotzebue1#ad in another part1
 speaks of the  rocks on the edge of the
 reef 8as visible for about two feet at 
low  water10 and these rocks we may feel
 quite certain are not formed of  true  
coral4#ae ,whether a smooth convex mound
 of ,nullipor1 like that  which appears 
as if artificially constructed to       
protect the margin of  ,keeling ,island1
 is of frequent occurrence round atolls1
 ,i know not2 but  we shall presently   
meet with it1 under precisely the same  

form1 on the  outer edge of the         
8barrier-reefs0 which encircle the      
,society ,islands4     #ac ,kotzebue's  
8,first ,voyage10 volume iii41 page     
#adb4 ,near ,porto   ,praya1 in the     
,cape de ,verde ,islands1 some basaltic 
rocks1 lashed by no   inconsiderable    
surf1 were completely enveloped with a  
layer of   ,nullipor4 ,the entire       
surface over many square inches1 was    
coloured of   a peach-blossomed red2 the
 layer1 however1 was of no greater      
thickness   than paper4 ,another kind1  
in the form of projecting knobs1 grew in
 the   same situation4 ,these ,nullipor 
are closely related to those described  
on the coral-reefs1 but ,i believe are  
of different species4       #ad         
,kotzebue1 8,first ,voyage10 volume ii41
 page #af4 ,lieutenant ,nelson1   in his
 excellent memoir in the ,geological    
,transactions 7volume ii41   page #aje71
 alludes to the rocky points mentioned  
by ,kotzebue1 and   infers that they    
consist of ,serpul1 which compose       

incrusting masses   on the reefs of     
,bermudas1 as they likewise do on a     
sandstone bar off   the coast of ,brazil
 7which ,i have described in 8,london   
,phil4 ,journal10   ,october #ahda74    
,these masses of ,serpul hold the same  
position1   relatively to the action of 
the sea1 with the ,nullipor on the      
coral-reefs in the ,indian and ,pacific 
,oceans4       #ae ,captain ,moresby1 in
 his valuable paper 8on the ,northern   
atolls of   ,maldivas0 78,geographical  
,journal01 volume v471 says that the    
edges of   the reefs there stand above  
water at low spring-tides4      ,there  
appears to be scarcely a feature in the 
structure of ,keeling  reef1 which is   
not of common1 if not of universal      
occurrence1 in other  atolls4 ,thus     
,chamisso describes#af a layer of coarse
 conglomerate1  outside the islets round
 the ,marshall atolls which 8appears on 
its  upper surface uneven and eaten     
away40 ,from drawings1 with appended    
remarks1 of ,diego ,garcia in the       

,chagos group and of several of the     
,maldiva atolls1 shown me by ,captain   
,moresby1#ag it is evident that  their  
outer coasts are subject to the same    
round of decay and  renovation as those 
of ,keeling atoll4 ,from the description
 of the  atolls in the ,low             
,archipelago1 given in ,captain         
,beechey's 8,voyage10 it  is not        
apparent that any conglomerate          
coral-rock was there observed4     #af  
,kotzebue's 8,first ,voyage10 volume    
iii41 page #add4       #ag ,see also    
,moresby on the ,northern atolls of the 
,maldivas1   8,geographical ,journal01  
volume v41 page #djj4      ,the lagoon  
in ,keeling atoll is shallow2 in the    
atolls of the ,low  ,archipelago the    
depth varies from #bj to #ch fathoms1   
and in the ,marshall  ,group1 according 
to ,chamisso1 from #cj to #ce2 in the   
,caroline atolls it  is only a little   
less4 ,within the ,maldiva atolls there 
are large spaces  with #de fathoms1 and 
some soundings are laid down of #di     

fathoms4 ,the  greater part of the      
bottom in most lagoons1 is formed of    
sediment2  large spaces have exactly the
 same depth1 or the depth varies so     
insensibly1 that it is evident that no  
other means1 excepting aqueous          
deposition1 could have leveled the      
surface so equally4 ,in the ,maldiva    
atolls this is very conspicuous1 and    
likewise in some of the ,caroline  and  
,marshall ,islands4 ,in the former large
 spaces consist of sand and  soft clay2 
and ,kotzebue speaks of clay having been
 found within one  of the ,marshall     
atolls4 ,no doubt this clay is          
calcareous mud1 similar  to that at     
,keeling ,island1 and to that at        
,bermuda already referred to1  as       
undistinguishable from disintegrated    
chalk1 and which ,lieutenant  ,nelson   
says is called there pipe-clay4#ah      
#ah ,i may here observe that on the     
coast of ,brazil1 where there is   much 
coral1 the soundings near the land are  
described by ,admiral   ,roussin1 in the

 ,pilote du ,brsil1 as siliceous sand1  
mingled with   much finely comminuted   
particles of shells and coral4 ,further 
in the   offing1 for a space of #a1cjj  
miles along the coast1 from the         
,abrolhos   ,islands to ,maranham1 the  
bottom in many places is composed of    
8tuf   blanc1 ml ou form de madrpores   
broys40 ,this white substance1          
probably1 is analogous to that which    
occurs within the above-mentioned       
lagoons2 it is sometimes1 according to  
,roussin1 firm1 and he compares   it to 
mortar4      ,where the waves act with  
unequal force on the two sides of an    
atoll1  the islets appear to be first   
formed1 and are generally of greater    
continuity on the more exposed shore4   
,the islets1 also1 which are  placed to 
leeward1 are in most parts of the       
,pacific liable to be  occasionally     
swept entirely away by gales1 equalling 
hurricanes in  violence1 which blow in  
an opposite direction to the ordinary   
trade-wind4 ,the absence of the islets  

on the leeward side of atolls1 or  when 
present their lesser dimensions compared
 with those to windward1  is a          
comparatively unimportant fact2 but in  
several instances the reef  itself on   
the leeward side1 retaining its usual   
defined outline1 does  not rise to the  
surface by several fathoms4 ,this is the
 case with the  southern side of ,peros 
,banhos 7,plate ,i41 ,figure #i7 in the 
,chagos group1  with ,mourileu atoll#ai 
in the ,caroline ,archipelago1 and with 
the  barrier-reef 7,plate ,i41 ,figure  
#h7 of the ,gambier ,islands4 ,i allude 
to  the latter reef1 although belonging 
to another class1 because ,captain      
,beechey was first led by it to observe 
the peculiarity in the question4  ,at   
,peros ,banhos the submerged part is    
nine miles in length1 and lies at  an   
average depth of about five fathoms2 its
 surface is nearly level1  and consists 
of hard stone1 with a thin covering of  
loose sand4 ,there  is scarcely any     
living coral on it1 even on the outer   

margin1 as ,i have  been particularly   
assured by ,captain ,moresby2 it is1 in 
fact1 a wall of  dead coral-rock1 having
 the same width and transverse section  
with the  reef in its ordinary state1 of
 which it is a continuous portion4 ,the 
living and perfect parts terminate      
abruptly1 and abut on the submerged     
portions1 in the same manner as on the  
sides of an ordinary passage  through   
the reef4 ,the reef to leeward in other 
cases is nearly or quite  obliterated1  
and one side of the lagoon is left open2
 for instance1 at  ,oulleay 7,caroline  
,archipelago71 where a crescent-formed  
reef is fronted  by an irregular bank1  
on which the other half of the annular  
reef  probably once stood4 ,at          
,namonouto1 in the same ,archipelago1   
both these  modifications of the reef   
concur2 it consists of a great flat     
bank1  with from twenty to twenty-five  
fathoms water on it2 for a length of    
more than forty miles on its southern   
side it is open and without any  reef1  

whilst on the other sides it is bounded 
by a reef1 in parts  rising to the      
surface and perfectly characterised1 in 
parts lying some  fathoms submerged4 ,in
 the ,chagos group there are annular    
reefs1  entirely submerged1 which have  
the same structure as the submerged and 
defined portions just described4 ,the   
,speaker's ,bank offers an excellent    
example of this structure2 its central  
expanse1 which is about  twenty-two     
fathoms deep1 is twenty-four miles      
across2 the external rim  is of the     
usual width of annular reefs1 and is    
well-defined2 it lies  between six and  
eight fathoms beneath the surface1 and  
at the same  depth there are scattered  
knolls in the lagoon4 ,captain ,moresby 
believes the rim consists of dead rock1 
thinly covered with sand1 and  he is    
certain this is the case with the       
external rim of the ,great  ,chagos     
,bank1 which is also essentially a      
submerged atoll4 ,in both these  cases1 
as in the submerged portion of the reef 

at ,peros ,banhos1 ,captain  ,moresby   
feels sure that the quantity of living  
coral1 even on the outer  edge          
overhanging the deep-sea water1 is quite
 insignificant4 ,lastly1 in  several    
parts of the ,pacific and ,indian       
,oceans there are banks1 lying  at      
greater depths than in the cases just   
mentioned1 of the same form  and size   
with the neighbouring atolls1 but with  
their atoll-like  structure wholly      
obliterated4 ,it appears from the survey
 of ,freycinet1  that there are banks of
 this kind in the ,caroline             
,archipelago1 and1 as  is reported1 in  
the ,low ,archipelago4 ,when we discuss 
the origin of the  different classes of 
coral formations1 we shall see that the 
submerged  state of the whole of some   
atoll-formed reefs1 and of portions of  
others1 generally but not invariably on 
the leeward side1 and the  existence of 
more deeply submerged banks now         
possessing little or no  signs of their 
original atoll-like structure1 are      

probably the effects  of a uniform      
cause1--namely1 the death of the coral1 
during the  subsidence of the area1 in  
which the atolls or banks are situated4 
#ai ,frederick ,lutk's 8,voyage autour  
du ,monde10 volume ii41 page #bia4      
,see also his account of ,namonouto1    
below1 and the chart of ,oulleay in     
the ,atlas4      ,there is seldom1 with 
the exception of the ,maldiva atolls1   
more than  two or three channels1 and   
generally only one leading into the     
lagoon1  of sufficient depth for a ship 
to enter4 in small atolls1 there is     
usually not even one4 ,where there is   
deep water1 for instance above  twenty  
fathoms1 in the middle of the lagoon1   
the channels through the  reef are      
seldom as deep as the centre1--it may be
 said that the rim only  of the         
saucer-shaped hollow forming the lagoon 
is notched4 ,mr4  ,lyell#bj has observed
 that the growth of the coral would tend
 to  obstruct all the channels through a
 reef1 except those kept open by        

discharging the water1 which during high
 tide and the greater part of  each ebb 
is thrown over its circumference4       
,several facts indicate that  a         
considerable quantity of sediment is    
likewise discharged through  these      
channels2 and ,captain ,moresby informs 
me that he has observed1  during the    
change of the monsoon1 the sea          
discoloured to a distance off  the      
entrances into the ,maldiva and ,chagos 
atolls4 ,this1 probably1 would  check   
the growth of the coral in them1 far    
more effectually than a mere  current of
 water4 ,in the many small atolls       
without any channel1 these  causes have 
not prevented the entire ring attaining 
the surface4 ,the  channels1 like the   
submerged and effaced parts of the reef1
 very  generally though not invariably  
occur on the leeward side of the atoll1 
or on that side1 according to           
,beechey1#ba which1 from running in the 
same direction with the prevalent wind1 
is not fully exposed to it4  ,passages  

between the islets on the reef1 through 
which boats can pass  at high water1    
must not be confounded with             
ship-channels1 by which the  annular    
reef itself is breached4 ,the passages  
between the islets occur1  of course1 on
 the windward as well as on the leeward 
side2 but they are  more frequent and   
broader to leeward1 owing to the lesser 
dimensions of  the islets on that side4 
#bj 8,principles of ,geology10 volume   
iii41 page #bhi4       #ba ,beechey's   
8,voyage10 #dto edition1 volume i41 page
 #ahi4      ,at ,keeling atoll the      
shores of the lagoon shelve gradually1  
where the  bottom is of sediment1 and   
irregularly or abruptly where there are 
coral-reefs2 but this is by no means the
 universal structure in other  atolls4  
,chamisso1#bb speaking in general terms 
of the lagoons in the  ,marshall atolls1
 says the lead generally sinks 8from a  
depth of two or  three fathoms to twenty
 or twenty-four1 and you may pursue a   
line in  which on one side of the boat  

you may see the bottom1 and on the other
  the azure-blue deep water40 ,the      
shores of the lagoon-like channel       
within the barrier-reef at ,vanikoro    
have a similar structure4 ,captain      
,beechey has described a modification of
 this structure 7and he believes  it is 
not uncommon7 in two atolls in the ,low 
,archipelago1 in which the  shores of   
the lagoon descend by a few1 broad1     
slightly inclined ledges  or steps3 thus
 at ,matilda atoll1#bc the great        
exterior reef1 the  surface of which is 
gently inclined towards and beneath the 
surface of  the lagoon1 ends abruptly in
 a little cliff three fathoms deep2 at  
its  foot1 a ledge forty yards wide     
extends1 shelving gently inwards like   
the surface-reef1 and terminated by a   
second little cliff five fathoms  deep2 
beyond this1 the bottom of the lagoon   
slopes to twenty fathoms1  which is the 
average depth of its centre4 ,these     
ledges seem to be  formed of coral-rock2
 and ,captain ,beechey says that the    

lead often  descended several fathoms   
through holes in them4 ,in some atolls1 
all  the coral reefs or knolls in the   
lagoon come to the surface at low       
water2 in other cases of rarer          
occurrence1 all lie at nearly the same  
depth beneath it1 but most frequently   
they are quite irregular1--some  with   
perpendicular1 some with sloping        
sides1--some rising to the  surface1 and
 others lying at all intermediate depths
 from the bottom  upwards4 ,i cannot1   
therefore1 suppose that the union of    
such reefs  could produce even one      
uniformly sloping ledge1 and much less  
two or  three1 one beneath the other1   
and each terminated by an abrupt wall4  
,at  ,matilda ,island1 which offers the 
best example of the step-like           
structure1 ,captain ,beechey observes   
that the coral-knolls within the  lagoon
 are quite irregular in their height4   
,we shall hereafter see that  the theory
 which accounts for the ordinary form of
 atolls1 apparently  includes this      

occasional peculiarity in their         
structure4     #bb ,kotzebue's 8,first  
,voyage10 volume iii41 page #adb4       
#bc ,beechey's 8,voyage10 #dto edition1 
volume i1 page #afj4 ,at   ,whitsunday  
,island the bottom of the lagoon slopes 
gradually towards   the centre1 and then
 deepens suddenly1 the edge of the bank 
being   nearly perpendicular4 ,this bank
 is formed of coral and dead shells4    
,in the midst of a group of atolls1     
there sometimes occur small1 flat1  very
 low islands of coral formation1 which  
probably once included a  lagoon1 since 
filled up with sediment and coral-reefs4
 ,captain ,beechey  entertains no doubt 
that this has been the case with the two
 small  islands1 which alone of         
thirty-one surveyed by him in the ,low  
,archipelago1 did not contain lagoons4  
,romanzoff ,island 7in lat4 #ae ,s47  is
 described by ,chamisso#bd  as formed by
 a dam of madreporitic rock inclosing a 
flat space1 thinly  covered with trees1 
into which the sea on the leeward side  

occasionally  breaks4 ,north ,keeling   
atoll appears to be in a rather less    
forward  stage of conversion into land2 
it consists of a horse-shoe shaped strip
  of land surrounding a muddy flat1 one 
mile in its longest axis1 which  is     
covered by the sea only at high water4  
,when describing ,south ,keeling  atoll1
 ,i endeavoured to show how slow the    
final process of filling up a  lagoon   
must be2 nevertheless1 as all causes do 
tend to produce this  effect1 it is very
 remarkable that not one instance1 as ,i
 believe1 is  known of a moderately     
sized lagoon being filled up even to the
 low  water-line at spring-tides1 much  
less of such a one being converted  into
 land4 ,it is1 likewise1 in some degree 
remarkable1 how few atolls1  except     
small ones1 are surrounded by a single  
linear strip of land1  formed by the    
union of separate islets4 ,we cannot    
suppose that the many  atolls in the    
,pacific and ,indian ,oceans all have   
had a late origin1 and  yet should they 

remain at their present level1 subjected
 only to the  action of the sea and to  
the growing powers of the coral1 during 
as  many centuries as must have elapsed 
since any of the earlier tertiary       
epochs1 it cannot1 ,i think1 be doubted 
that their lagoons and the  islets on   
their reef1 would present a totally     
different appearance from  what they now
 do4 ,this consideration leads to the   
suspicion that some  renovating agency  
7namely subsidence7 comes into play at  
intervals1 and  perpetuates their       
original structure4     #bd ,kotzebue's 
8,first ,voyage10 volume iii41 page     
#bba4    ,,section ,,iii4--,,atolls ,,of
 ,,the ,,maldiva ,,archipelago--,,great 
,,chagos ,,bank4    ,maldiva            
,archipelago4--,ring-formed reefs1      
marginal and central4--,great  depths in
 the lagoons of the southern            
atolls4--,reefs in the lagoons all      
rising to the surface4--,position of    
islets and breaches in the reefs1  with 
respect to the prevalent winds and      

action of the  waves4--,destruction of  
islets4--,connection in the position and
 submarine  foundation of distinct      
atolls4--,the apparent disseverment of  
large  atolls4--,the ,great ,chagos     
,bank4--,its submerged condition and    
extraordinary structure4      ,although 
occasional references have been made to 
the ,maldiva atolls1  and to the banks  
in the ,chagos group1 some points of    
their structure  deserve further        
consideration4 ,my description is       
derived from an  examination of the     
admirable charts lately published from  
the survey of  ,captain ,moresby and    
,lieutenant ,powell1 and more especially
 from  information which ,captain       
,moresby has communicated to me in the  
kindest  manner4    ,the ,maldiva       
,archipelago is #dgj miles in length1   
with an average breadth  of about #ej   
miles4 ,the form and dimensions of the  
atolls1 and their  singular position in 
a double line1 may be seen1 but not     
well1 in the  greatly reduced chart     

7,figure #f7 in ,plate ,,ii4 ,the       
dimensions of the  longest atoll in the 
group 7called by the double name of     
,milla-dou-,madou and ,tilla-dou-,matte7
 have already been given2 it is #hh     
miles in a medial and slightly curved   
line1 and is less than #bj miles  in its
 broadest part4 ,suadiva1 also1 is a    
noble atoll1 being #dd miles  across in 
one direction1 and #cd in another1 and  
the great included  expanse of water has
 a depth of between #bej and #cjj feet4 
,the smaller  atolls in this group      
differ in no respect from ordinary ones2
 but the  larger ones are remarkable    
from being breached by numerous         
deep-water  channels leading into the   
lagoon2 for instance1 there are #db     
channels1  through which a ship could   
enter the lagoon of ,suadiva4 ,in the   
three  southern large atolls1 the       
separate portions of reef between these 
channels have the ordinary structure1   
and are linear2 but in the other        
atolls1 especially the more northern    

ones1 these portions are ring-  formed1 
like miniature atolls4 ,other           
ring-formed reefs rise out of the       
lagoons1 in the place of those irregular
 ones which ordinarily occur  there4 ,in
 the reduction of the chart of ,mahlos  
,mahdoo 7,plate ,,ii41  ,figure #d71 it 
was not found easy to define the islets 
and the little  lagoons within each     
reef1 so that the ring-formed structure 
is very  imperfectly shown2 in the large
 published charts of ,tilla-dou-,matte1 
the appearance of these rings1 from     
standing further apart from each  other1
 is very remarkable4 ,the rings on the  
margin are generally  elongated2 many of
 them are three1 and some even five     
miles1 in  diameter2 those within the   
lagoon are usually smaller1 few being   
more  than two miles across1 and the    
greater number rather less than one4    
,the  depth of the little lagoon within 
these small annular reefs is  generally 
from five to seven fathoms1 but         
occasionally more2 and in ,ari  atoll   

many of the central ones are twelve1 and
 some even more than  twelve fathoms    
deep4 ,these rings rise abruptly from   
the platform or  bank1 on which they are
 placed2 their outer margin is          
invariably  bordered by living coral#be 
within which there is a flat surface of 
coral rock2 of this flat1 sand and      
fragments have in many cases            
accumulated and been converted into     
islets1 clothed with vegetation4 ,i     
can1 in fact1 point out no essential    
difference between these little         
ring-formed reefs 7which1 however1 are  
larger1 and contain deeper  lagoons than
 many true atolls that stand in the open
 sea71 and the most  perfectly          
characterised atolls1 excepting that the
 ring-formed reefs  are based on a      
shallow foundation1 instead of on the   
floor of the open  sea1 and that instead
 of being scattered irregularly1 they   
are grouped  closely together on one    
large platform1 with the marginal rings 
arranged in a rudely formed circle4     

#be ,captain ,moresby informs me that   
,millepora complanata is one of   the   
commonest kinds on the outer margin1 as 
it is at ,keeling atoll4      ,the      
perfect series which can be traced from 
portions of simple linear  reef1 to     
others including long linear lagoons1   
and from these again to  oval or almost 
circular rings1 renders it probable that
 the latter are  merely modifications of
 the linear or normal state4 ,it is     
conformable  with this view1 that the   
ring-formed reefs on the margin1 even   
where  most perfect and standing        
furthest apart1 generally have their    
longest  axes directed in the line which
 the reef would have held1 if the atoll 
had been bounded by an ordinary wall4   
,we may also infer that the  central    
ring-formed reefs are modifications of  
those irregular ones1  which are found  
in the lagoons of all common atolls4 ,it
 appears from  the charts on a large    
scale1 that the ring-like structure is  
contingent  on the marginal channels or 

breaches being wide2 and1 consequently1 
on  the whole interior of the atoll     
being freely exposed to the waters of   
the open sea4 ,when the channels are    
narrow or few in number1 although  the  
lagoon be of great size and depth 7as in
 ,suadiva71 there are no  ring-formed   
reefs2 where the channels are somewhat  
broader1 the  marginal portions of reef1
 and especially those close to the      
larger  channels1 are ring-formed1 but  
the central ones are not so2 where they 
are broadest1 almost every reef         
throughout the atoll is more or less    
perfectly ring-formed4 ,although their  
presence is thus contingent on  the     
openness of the marginal channels1 the  
theory of their formation1  as we shall 
hereafter see1 is included in that of   
the parent atolls1 of  which they form  
the separate portions4    ,the lagoons  
of all the atolls in the southern part  
of the ,archipelago  are from ten to    
twenty fathoms deeper than those in the 
northern part4  ,this is well           

exemplified in the case of ,addoo1 the  
southernmost atoll  in the group1 for   
although only nine miles in its longest 
diameter1 it  has a depth of thirty-nine
 fathoms1 whereas all the other small   
atolls  have comparatively shallow      
lagoons2 ,i can assign no adequate cause
 for  this difference in depth4 ,in the 
central and deepest part of the         
lagoons1 the bottom consists1 as ,i am  
informed by ,captain ,moresby1 of  stiff
 clay 7probably a calcareous mud72      
nearer the border it consists  of sand1 
and in the channels through the reef1 of
 hard sand-banks1  sandstone1           
conglomerate rubble1 and a little live  
coral4 ,close outside  the reef and the 
line joining its detached portions      
7where intersected  by many channels71  
the bottom is sandy1 and it slopes      
abruptly into  unfathomable depths4 ,in 
most lagoons the depth is considerably  
greater  in the centre than in the      
channels2 but in ,tilla-dou-,matte1     
where the  marginal ring-formed reefs   

stand far apart1 the same depth is      
carried  across the entire atoll1 from  
the deep-water line on one side to that 
on the other4 ,i cannot refrain from    
once again remarking on the  singularity
 of these atolls1--a great sandy and    
generally concave disc  rises abruptly  
from the unfathomable ocean1 with its   
central expanse  studded and its border 
symmetrically fringed with oval basins  
of  coral-rock1 just lipping the surface
 of the sea1 sometimes clothed with     
vegetation1 and each containing a little
 lake of clear water6    ,in the        
southern ,maldiva atolls1 of which there
 are nine large ones1 all  the small    
reefs within the lagoons come to the    
surface1 and are dry at  low water      
spring-tides2 hence in navigating them1 
there is no danger  from submarine      
banks4 ,this circumstance is very       
remarkable1 as within  some atolls1 for 
instance those of the neighbouring      
,chagos group1 not a  single reef comes 
to the surface1 and in most other cases 

a few only  do1 and the rest lie at all 
intermediate depths from the bottom     
upwards4 ,when treating of the growth of
 coral ,i shall again refer to  this    
subject4    ,although in the            
neighbourhood of the ,maldiva           
,archipelago the winds1  during the     
monsoons1 blow during nearly an equal   
time from opposite  quarters1 and       
although1 as ,i am informed by ,captain 
,moresby1 the  westerly winds are the   
strongest1 yet the islets are almost all
 placed  on the eastern side of the     
northern atolls1 and on the             
south-eastern  side of the southern     
atolls4 ,that the formation of the      
islets is due to  detritus thrown up    
from the outside1 as in the ordinary    
manner1 and not  from the interior of   
the lagoons1 may1 ,i think be safely    
inferred from  several considerations1  
which it is hardly worth while to       
detail4 ,as  the easterly winds are not 
the strongest1 their action probably is 
aided by some prevailing swell or       

current4    ,in groups of atolls1       
exposed to a trade-wind1 the            
ship-channels into  the lagoons are     
almost invariably situated on the       
leeward or less  exposed side of the    
reef1 and the reef itself is sometimes  
either  wanting there1 or is submerged4 
,a strictly analogous1 but different    
fact1 may be observed at the ,maldiva   
atolls--namely1 that where two  atolls  
stand in front of each other1 the       
breaches in the reef are the  most      
numerous on their near1 and therefore   
less exposed1 sides4 ,thus on  the near 
sides of ,ari and the two ,nillandoo    
atolls1 which face ,s4 ,mle1            
,phaleedoo1 and ,moloque atolls1 there  
are seventy-three deep-water  channels1 
and only twenty-five on their outer     
sides2 on the near side  of the three   
latter named atolls there are fifty- six
 openings1 and  only thirty-seven on    
their outsides4 ,it is scarcely possible
 to  attribute this difference to any   
other cause than the somewhat  different

 action of the sea on the two sides1    
which would ensue from  the protection  
afforded by the two rows of atolls to   
each other4 ,i may  here remark that in 
most cases1 the conditions favourable to
 the  greater accumulation of fragments 
on the reef and to its more perfect     
continuity on one side of the atoll than
 on the other1 have concurred1  but this
 has not been the case with the         
,maldivas2 for we have seen that  the   
islets are placed on the eastern or     
south-eastern sides1 whilst the         
breaches in the reef occur indifferently
 on any side1 where protected  by an    
opposite atoll4 ,the reef being more    
continuous on the outer and  more       
exposed sides of those atolls which     
stand near each other1 accords  with the
 fact1 that the reef of the southern    
atolls is more continuous  than that of 
the northern ones2 for the former1 as ,i
 am informed by  ,captain ,moresby1 are 
more constantly exposed than the        
northern atolls  to a heavy surf4       

,the date of the first formation of some
 of the islets in this  ,archipelago is 
known to the inhabitants2 on the other  
hand1 several  islets1 and even some of 
those which are believed to be very old1
 are  now fast wearing away4 ,the work  
of destruction has1 in some instances1  
been completed in ten years4 ,captain   
,moresby found on one water-washed  reef
 the marks of wells and graves1 which   
were excavated when it  supported an    
islet4 ,in ,south ,nillandoo atoll1 the 
natives say that  three of the islets   
were formerly larger3 in ,north         
,nillandoo there is  one now being      
washed away2 and in this latter atoll   
,lieutenant ,prentice  found a reef1    
about six hundred yards in diameter1    
which the natives  positively affirmed  
was lately an island covered with       
cocoa-nut trees4  ,it is now only       
partially dry at low water spring-tides1
 and is 7in  ,lieutenant ,prentice's    
words7 8entirely covered with live coral
 and  madrepore40 ,in the northern part1

 also1 of the ,maldiva ,archipelago and 
in the ,chagos group1 it is known that  
some of the islets are  disappearing4   
,the natives attribute these effects to 
variations in the  currents of the sea4 
,for my own part ,i cannot avoid        
suspecting that  there must be some     
further cause1 which gives rise to such 
a cycle of  change in the action of the 
currents of the great and open ocean4   
,several of the atolls in this          
,archipelago are so related to each     
other  in form and position1 that at the
 first glance one is led to suspect     
that they have originated in the        
disseverment of a single one4 ,mle      
consists of three perfectly             
characterised atolls1 of which the shape
  and relative position are such1 that a
 line drawn closely round all  three1   
gives a symmetrical figure2 to see this 
clearly1 a larger chart  is required    
than that of the ,archipelago in ,plate 
,,ii42 the channel  separating the two  
northern ,mle atolls is only little more

 than a mile  wide1 and no bottom was   
found in it with #ajj fathoms4 ,powell's
 ,island  is situated at the distance of
 two miles and a half off the northern  
end of ,mahlos ,mahdoo 7see ,figure #d1 
,plate ,,ii471 at the exact point  where
 the two sides of the latter1 if        
prolonged1 would meet2 no bottom1       
however1 was found in the channel with  
#bjj fathoms2 in the wider  channel     
between ,horsburgh atoll and the        
southern end of ,mahlos ,mahdoo1  no    
bottom was found with #bej fathoms4 ,in 
these and similar cases1 the  relation  
consists only in the form and position  
of the atolls4 ,but in  the channel     
between the two ,nillandoo atolls1      
although three miles and  a quarter     
wide1 soundings were struck at the depth
 of #bjj fathoms2 the  channel between  
,ross and ,ari atolls is four miles     
wide1 and only #aej  fathoms deep4 ,here
 then we have1 besides the relation of  
form1 a  submarine connection4 ,the fact
 of soundings having been obtained      

between two separate and perfectly      
characterised atolls is in itself       
interesting1 as it has never1 ,i        
believe1 been effected in any of the    
many other groups of atolls in the      
,pacific and ,indian seas4 ,in          
continuing to trace the connection of   
adjoining atolls1 if a hasty  glance be 
taken at the chart 7,figure #d41 ,plate 
,,ii47 of ,mahlos ,mahdoo1  and the line
 of unfathomable water be followed1 no  
one will hesitate to  consider it as one
 atoll4 ,but a second look will show    
that it is  divided by a bifurcating    
channel1 of which the northern arm is   
about  one mile and three-quarters in   
width1 with an average depth of #abe    
fathoms1 and the southern one           
three-quarters of a mile wide1 and      
rather  less deep4 ,these channels      
resemble in the slope of their sides and
  general form1 those which separate    
atolls in every respect distinct2  and  
the northern arm is wider than that     
dividing two of the ,mle  atolls4 ,the  

ring-formed reefs on the sides of this  
bifurcating channel  are elongated1 so  
that the northern and southern portions 
of ,mahlos  ,mahdoo may claim1 as far as
 their external outline is concerned1 to
 be  considered as distinct and perfect 
atolls4 ,but the intermediate  portion1 
lying in the fork of the channel1 is    
bordered by reefs less  perfect than    
those which surround any other atoll in 
the group of  equally small dimensions4 
,mahlos ,mahdoo1 therefore1 is in every 
respect  in so intermediate a condition1
 that it may be considered either as a  
single atoll nearly dissevered into     
three portions1 or as three atolls      
almost perfect and intimately connected4
 ,this is an instance of a very  early  
stage of the apparent disseverment of an
 atoll1 but a still  earlier one in many
 respects is exhibited at ,tilla-dou-   
,matte4 ,in one  part of this atoll1 the
 ring-formed reefs stand so far apart   
from each  other1 that the inhabitants  
have given different names to the       

northern  and southern halves2 nearly   
all the rings1 moreover1 are so perfect 
and  stand so separate1 and the space   
from which they rise is so level and    
unlike a true lagoon1 that we can easily
 imagine the conversion of this  one    
great atoll1 not into two or three      
portions1 but into a whole group  of    
miniature atolls4 ,a perfect series such
 as we have here traced1  impresses the 
mind with an idea of actual change2 and 
it will hereafter  be seen1 that the    
theory of subsidence1 with the upward   
growth of the  coral1 modified by       
accidents of probable occurrence1 will  
account for  the occasional disseverment
 of large atolls4    ,the ,great ,chagos
 bank alone remains to be described4 ,in
 the ,chagos  group there are some      
ordinary atolls1 some annular reefs     
rising to the  surface but without any  
islets on them1 and some atoll-formed   
banks1  either quite submerged1 or      
nearly so4 ,of the latter1 the ,great   
,chagos  ,bank is much the largest1 and 

differs in its structure from the       
others3  a plan of it is given in ,plate
 ,,ii41 ,figure #a1 in which1 for the   
sake of  clearness1 ,i have had the     
parts under ten fathoms deep finely     
shaded3  an east and west vertical      
section is given in ,figure #b1 in which
 the  vertical scale has been           
necessarily exaggerated4 ,its longest   
axis is  ninety nautical miles1 and     
another line drawn at right angles to   
the  first1 across the broadest part1 is
 seventy4 ,the central part consists  of
 a level muddy flat1 between forty and  
fifty fathoms deep1 which is  surrounded
 on all sides1 with the exception of    
some breaches1 by the  steep edges of a 
set of banks1 rudely arranged in a      
circle4 ,these banks  consist of sand1  
with a very little live coral2 they vary
 in breadth  from five to twelve miles1 
and on an average lie about sixteen     
fathoms  beneath the surface2 they are  
bordered by the steep edges of a third  
narrow and upper bank1 which forms the  

rim to the whole4 ,this rim is  about a 
mile in width1 and with the exception of
 two or three spots  where islets have  
been formed1 is submerged between five  
and ten  fathoms4 ,it consists of smooth
 hard rock1 covered with a thin layer of
  sand1 but with scarcely any live      
coral2 it is steep on both sides1 and   
outwards slopes abruptly into           
unfathomable depths4 ,at the distance of
  less than half a mile from one part1  
no bottom was found with #aij  fathoms2 
and off another point1 at a somewhat    
greater distance1 there  was none with  
#baj fathoms4 ,small steep-sided banks  
or knolls1 covered  with luxuriantly    
growing coral1 rise from the interior   
expanse to the  same level with the     
external rim1 which1 as we have seen1 is
 formed  only of dead rock4 ,it is      
impossible to look at the plan 7,figure 
#a1  ,plate ,,ii471 although reduced to 
so small a scale1 without at once       
perceiving that the ,great ,chagos ,bank
 is1 in the words of ,captain           

,moresby1#bf 8nothing more than a       
half-drowned atoll40 ,but of what  great
 dimensions1 and of how extraordinary an
 internal structure8 ,we  shall         
hereafter have to consider both the     
cause of its submerged  condition1 a    
state common to other banks in the      
group1 and the origin  of the singular  
submarine terraces1 which bound the     
central expanse3  these1 ,i think1 it   
can be shown1 have resulted from a cause
 analogous  to that which has produced  
the bifurcating channel across ,mahlos  
,mahdoo4     #bf ,this officer has had  
the kindness to lend me an excellent    
,,ms4   account of the ,chagos ,islands2
 from this paper1 from the published    
charts1 and from verbal information     
communicated to me by ,captain          
,moresby1 the above account of the      
,great ,chagos ,bank is taken4          
,,chapter ,,ii4    ,,barrier ,,reefs4   
,closely resemble in general form and   
structure atoll-reefs4--,width and      
depth of the lagoon-channels4--,breaches

 through the reef in front of  valleys1 
and generally on the leeward            
side4--,checks to the filling up of  the
 lagoon-channels4--,size and            
constitution of the encircled islands4--
  ,number of islands within the same    
reef4--,barrier-reefs of ,new ,caledonia
  and ,australia4--,position of the reef
 relative to the slope of the  adjoining
 land4--,probable great thickness of    
barrier-reefs4      ,the term 8barrier0 
has been generally applied to that vast 
reef which  fronts the ,n4,e4 shore of  
,australia1 and by most voyagers        
likewise to  that on the western coast  
of ,new ,caledonia4 ,at one time ,i     
thought it  convenient thus to restrict 
the term1 but as these reefs are similar
 in  structure1 and in position         
relatively to the land1 to those1 which1
  like a wall with a deep moat within1  
encircle many smaller islands1 ,i  have 
classed them together4 ,the reef1 also1 
on the west coast of ,new  ,caledonia1  
circling round the extremities of the   

island1 is an  intermediate form between
 a small encircling reef and the        
,australian  barrier1 which stretches   
for a thousand miles in nearly a        
straight  line4    ,the geographer      
,balbi has in effect described those    
barrier-reefs1 which  encircle          
moderately sized islands1 by calling    
them atolls with high  land rising from 
within their central expanse4 ,the      
general resemblance  between the reefs  
of the barrier and atoll classes may be 
seen in the  small1 but accurately      
reduced charts on ,plate ,i41#a and this
  resemblance can be further shown to   
extend to every part of the  structure4 
,beginning with the outside of the reef2
 many scattered  soundings off ,gambier1
 ,oualan1 and some other encircled      
islands1 show  that close to the        
breakers there exists a narrow shelving 
margin1  beyond which the ocean becomes 
suddenly unfathomable2 but off the west 
coast of ,new ,caledonia1 ,captain      
,kent#b found no bottom with #aej       

fathoms1 at two ships' length from the  
reef2 so that the slope here  must be   
nearly as precipitous as off the        
,maldiva atolls4     #a ,the authorities
 from which these charts have been      
reduced1   together with some remarks on
 them and descriptive of the ,plates1   
are   given separately4       #b        
,dalrymple1 8,hydrog4 ,mem40 volume iii4
      ,i can give little information    
regarding the kinds of corals which live
  on the outer margin4 ,when ,i visited 
the reef at ,tahiti1 although it was    
low water1 the surf was too violent for 
me to see the living masses2  but1      
according to what ,i heard from some    
intelligent native chiefs1  they        
resemble in their rounded and branchless
 forms1 those on the  margin of ,keeling
 atoll4 ,the extreme verge of the reef1 
which was  visible between the breaking 
waves at low water1 consisted of a      
rounded1 convex1 artificial-like        
breakwater1 entirely coated with        
,nullipor1 and absolutely similar to    

that which ,i have described at         
,keeling atoll4 ,from what ,i heard when
 at ,tahiti1 and from the writings  of  
the ,revs4 ,w4 ,ellis and ,j4 ,williams1
 ,i conclude that this peculiar         
structure is common to most of the      
encircled islands of the ,society       
,archipelago4 ,the reef within this     
mound or breakwater1 has an extremely   
irregular surface1 even more so than    
between the islets on the reef of       
,keeling atoll1 with which alone 7as    
there are no islets on the reef of      
,tahiti7 it can properly be compared4   
,at ,tahiti1 the reef is very  irregular
 in width2 but round many other         
encircled islands1 for  instance1       
,vanikoro or ,gambier ,islands 7,figures
 #a and #h1 ,plate ,i471 it  is quite as
 regular1 and of the same average width1
 as in true atolls4  ,most barrier-reefs
 on the inner side slope irregularly    
into the  lagoon-channel 7as the space  
of deep water separating the reef from  
the  included land may be called71 but  

at ,vanikoro the reef slopes only for  a
 short distance1 and then terminates    
abruptly in a submarine wall1  forty    
feet high1--a structure absolutely      
similar to that described by  ,chamisso 
in the ,marshall atolls4    ,in the     
,society ,archipelago1 ,ellis#c states1 
that the reefs generally  lie at the    
distance of from one to one and a half  
miles1 and1  occasionally1 even at more 
than three miles1 from the shore4 ,the  
central mountains are generally bordered
 by a fringe of flat1 and often  marshy1
 alluvial land1 from one to four miles  
in width4 ,this fringe  consists of     
coral-sand and detritus thrown up from  
the lagoon-channel1  and of soil washed 
down from the hills2 it is an           
encroachment on the  channel1 analogous 
to that low and inner part of the islets
 in many  atolls which is formed by the 
accumulation of matter from the lagoon4 
,at ,hogoleu 7,figure #b1 ,plate ,i471  
in the ,caroline ,archipelago1#d the    
reef on the south side is no less than  

twenty miles2 on the east side1  five2  
and on the north side1 fourteen miles   
from the encircled high  islands4     #c
 ,consult1 on this and other points1 the
 8,polynesian ,researches10 by   the    
,rev4 ,w4 ,ellis1 an admirable work1    
full of curious information4       #d   
,see 8,hydrographical ,mem40 and the    
8,atlas of the ,voyage of the           
,astrolabe10 by ,captain ,dumont        
,d',urville1 page #dbh4      ,the lagoon
 channels may be compared in every      
respect with true lagoons4  ,in some    
cases they are open1 with a level bottom
 of fine sand2 in  others they are      
choked up with reefs of delicately      
branched corals1  which have the same   
general character as those within the   
,keeling  atoll4 ,these internal reefs  
either stand separately1 or more        
commonly  skirt the shores of the       
included high islands4 ,the depth of the
  lagoon-channel round the ,society     
,islands varies from two or three to    
thirty fathoms2 in ,cook's#e chart of   

,ulieta1 however1 there is one  sounding
 laid down of forty-eight fathoms2 at   
,vanikoro there are  several of         
fifty-four and one of fifty-six and a   
half fathoms  7,english71 a depth which 
even exceeds by a little that of the    
interior  of the great ,maldiva atolls4 
,some barrier-reefs have very few islets
 on  them2 whilst others are surmounted 
by numerous ones2 and those round  part 
of ,bolabola 7,plate ,i41 ,figure #e7   
form a single linear strip4 ,the  islets
 first appear either on the angles of   
the reef1 or on the sides  of the       
breaches through it1 and are generally  
most numerous on the  windward side4    
,the reef to leeward retaining its usual
 width1 sometimes  lies submerged       
several fathoms beneath the surface2 ,i 
have already  mentioned ,gambier ,island
 as an instance of this structure4      
,submerged  reefs1 having a less defined
 outline1 dead1 and covered with sand1  
have  been observed 7see ,appendix7 off 
some parts of ,huaheine and ,tahiti4    

,the  reef is more frequently breached  
to leeward than to windward2 thus ,i    
find in ,krusenstern's 8,memoir on the  
,pacific10 that there are passages      
through the encircling reef on the      
leeward side of each of the seven       
,society ,islands1 which possess        
ship-harbours2 but that there are       
openings to windward through the reef of
 only three of them4 ,the  breaches in  
the reef are seldom as deep as the      
interior lagoon-like  channel2 they     
generally occur in front of the main    
valleys1 a  circumstance which can be   
accounted for1 as will be seen in the   
fourth  chapter1 without much           
difficulty4 ,the breaches being situated
 in front  of the valleys1 which descend
 indifferently on all sides1 explains   
their more frequent occurrence through  
the windward side of  barrier-reefs than
 through the windward side of           
atolls1--for in atolls  there is no     
included land to influence the position 
of the breaches4     #e ,see the chart  

in volume i4 of ,hawkesworth's #dto     
edition of 8,cook's   ,first ,voyage40  
,it is remarkable1 that the             
lagoon-channels round mountainous       
islands  have not in every instance been
 long ago filled up with coral and      
sediment2 but it is more easily         
accounted for than appears at first     
sight4 ,in cases like that of ,hogoleu  
and the ,gambier ,islands1 where a  few 
small peaks rise out of a great lagoon1 
the conditions scarcely  differ from    
those of an atoll1 and ,i have already  
shown1 at some  length1 that the filling
 up of a true lagoon must be an         
extremely slow  process4 ,where the     
channel is narrow1 the agency1 which on 
unprotected  coasts is most productive  
of sediment1 namely the force of the    
breakers1 is here entirely excluded1 and
 the reef being breached in the  front  
of the main valleys1 much of the finer  
mud from the rivers must  be transported
 into the open sea4 ,as a current is    
formed by the water  thrown over the    

edge of atoll-formed reefs1 which       
carries sediment with  it through the   
deep-water breaches1 the same thing     
probably takes place  in barrier-reefs1 
and this would greatly aid in preventing
 the  lagoon-channel from being filled  
up4 ,the low alluvial border1 however1  
at the foot of the encircled mountains1 
shows that the work of filling  up is in
 progress2 and at ,maura 7,plate ,i41   
,figure #f71 in the ,society  group1 it 
has been almost effected1 so that there 
remains only one  harbour for small     
craft4    ,if we look at a set of charts
 of barrier-reefs1 and leave out in     
imagination the encircled land1 we shall
 find that1 besides the many  points    
already noticed of resemblance1 or      
rather of identity in  structure with   
atolls1 there is a close general        
agreement in form1  average dimensions1 
and grouping4 ,encircling barrier-reefs1
 like  atolls1 are generally elongated1 
with an irregularly rounded1 though     
sometimes angular outline4 ,there are   

atolls of all sizes1 from less  than two
 miles in diameter to sixty miles       
7excluding ,tilla-dou-,matte1  as it    
consists of a number of almost          
independent atoll-formed reefs72  and   
there are encircling barrier-reefs from 
three miles and a half to  forty-six    
miles in diameter1--,turtle ,island     
being an instance of the  former1 and   
,hogoleu of the latter4 ,at ,tahiti the 
encircled island is  thirty-six miles in
 its longest axis1 whilst at ,maurua it 
is only a  little more than two miles4  
,it will be shown1 in the last chapter  
in  this volume1 that there is the      
strictest resemblance in the grouping of
  atolls and of common islands1 and     
consequently there must be the same     
resemblance in the grouping of atolls   
and of encircling barrier-reefs4    ,the
 islands lying within reefs of this     
class1 are of very various  heights4    
,tahiti#f is #g1jjj feet2 ,maurua about 
#hjj2 ,aitutaki #cfj1 and  ,manouai only
 #ej4 ,the geological nature of the     

included land varies3 in  most cases it 
is of ancient volcanic origin1 owing    
apparently to the  fact that islands of 
this nature are most frequent within all
 great  seas2 some1 however1 are of     
madreporitic limestone1 and others of   
primary formation1 of which latter kind 
,new ,caledonia offers the best         
example4 ,the central land consists     
either of one island1 or of several3    
thus1 in the ,society group1 ,eimeo     
stands by itself2 while ,taha and       
,raiatea 7,figure #c1 ,plate ,i471 both 
moderately large islands of nearly      
equal size1 are included in one reef4   
,within the reef of the ,gambier  group 
there are four large and some smaller   
islands 7,figure #h1 ,plate  ,i472      
within that of ,hogoleu 7,figure #b1    
,plate ,i47 nearly a dozen small        
islands are scattered over the expanse  
of one vast lagoon4     #f ,the height  
of ,tahiti is given from ,captain       
,beechey2 ,maurua from   ,mr4 ,f4,d4    
,bennett 78,geograph4 ,journ40 volume   

viii41 page #bbj72 ,aitutaki   from     
measurements made on board the ,beagle2 
and ,manouai or ,harvey   ,island1 from 
an estimate by the ,rev4 ,j4 ,williams4 
,the two latter   islands1 however1 are 
not in some respects well characterised 
examples   of the encircled class4      
,after the details now given1 it may be 
asserted that there is not one  point of
 essential difference between encircling
 barrier-reefs and  atolls3 the latter  
enclose a simple sheet of water1 the    
former encircle  an expanse with one or 
more islands rising from it4 ,i was much
 struck  with this fact1 when viewing1  
from the heights of ,tahiti1 the distant
  island of ,eimeo standing within      
smooth water1 and encircled by a ring   
of snow-white breakers4 ,remove the     
central land1 and an annular reef  like 
that of an atoll in an early stage of   
its formation is left2  remove it from  
,bolabola1 and there remains a circle of
 linear  coral-islets1 crowned with tall
 cocoa-nut trees1 like one of the many  

atolls scattered over the ,pacific and  
,indian ,oceans4    ,the barrier-reefs  
of ,australia and of ,new ,caledonia    
deserve a separate  notice from their   
great dimensions4 ,the reef on the west 
coast of ,new  ,caledonia 7,figure #e1  
,plate ,,ii47 is #djj miles in length2  
and for a  length of many leagues it    
seldom approaches within eight miles of 
the  shore2 and near the southern end of
 the island1 the space between the  reef
 and the land is sixteen miles in width4
 ,the ,australian barrier  extends1 with
 a few interruptions1 for nearly a      
thousand miles2 its  average distance   
from the land is between twenty and     
thirty miles2 and  in some parts from   
fifty to seventy4 ,the great arm of the 
sea thus  included1 is from ten to      
twenty-five fathoms deep1 with a sandy  
bottom2  but towards the southern end1  
where the reef is further from the      
shore1  the depth gradually increases to
 forty1 and in some parts to more than  
sixty fathoms4 ,flinders#g has described

 the surface of this reef as  consisting
 of a hard white agglomerate of         
different kinds of coral1  with rough   
projecting points4 ,the outer edge is   
the highest part2 it is  traversed by   
narrow gullies1 and at rare intervals is
 breached by  ship-channels4 ,the sea   
close outside is profoundly deep2 but1  
in front  of the main breaches1         
soundings can sometimes be obtained4    
,some low  islets have been formed on   
the reef4     #g ,flinders' 8,voyage to 
,terra ,australis10 volume ii41 page    
#hh4      ,illustration    #a4          
,,vanikoro1 from the 8,atlas of the     
,voyage of the ,astrolabe10 by ,d4      
,d',urville4    #b4 ,,gambier ,,island1 
from ,beechey4    #c4 ,,maurua1 from the
 8,atlas of the ,voyage of the          
,coquille10 by  ,duperrey4    ,the      
horizontal line is the level of the sea1
 from which on the right  hand a plummet
 descends1 representing a depth of #bjj 
fathoms1 or #a1bjj  feet4 ,the vertical 
shading shows the section of the land1  

and the  horizontal shading that of the 
encircling barrier-reef3 from the       
smallness of the scale1 the             
lagoon-channel could not be represented4
    ,,aa4--,outer edge of the           
coral-reefs1 where the sea breaks4      
,,bb4--,the shore of the encircled      
islands47    ,there is one important    
point in the structure of barrier-reefs 
which  must here be considered4 ,the    
accompanying diagrams represent north   
and  south vertical sections1 taken     
through the highest points of ,vanikoro1
  ,gambier1 and ,maurua ,islands1 and   
through their encircling reefs4 ,the    
scale both in the horizontal and        
vertical direction is the same1  namely1
 a quarter of an inch to a nautical     
mile4 ,the height and width  of these   
islands is known2 and ,i have attempted 
to represent the form  of the land from 
the shading of the hills in the large   
published  charts4 ,it has long been    
remarked1 even from the time of         
,dampier1 that  considerable degree of  

relation subsists between the           
inclination of  that part of the land   
which is beneath water and that above   
it2 hence  the dotted line in the three 
sections1 probably1 does not widely     
differ  in inclination from the actual  
submarine prolongation of the land4 ,if 
we now look at the outer edge of the    
reef 7,,aa71 and bear in mind that  the 
plummet on the right hand represents a  
depth of #a1bjj feet1 we must  conclude 
that the vertical thickness of these    
barrier coral-reefs is  very great4     
,i must observe that if the sections had
 been taken in any other  direction     
across these islands1 or across other   
encircled islands1#h  the result would  
have been the same4 ,in the succeeding  
chapter it will  be shown that          
reef-building polypifers cannot flourish
 at great  depths1--for instance1 it is 
highly improbable that they could exist 
at  a quarter of the depth represented  
by the plummet on the right hand of  the
 woodcut4 ,here there is a great        

apparent difficulty--how were the  basal
 parts of these barrier-reef formed8 ,it
 will1 perhaps1 occur to  some1 that the
 actual reefs formed of coral are not of
 great thickness1  but that before their
 first growth1 the coasts of these      
encircled  islands were deeply eaten    
into1 and a broad but shallow submarine 
ledge  thus left1 on the edge of which  
the coral grew2 but if this had been    
the case1 the shore would have been     
invariably bounded by lofty cliffs1  and
 not have sloped down to the            
lagoon-channel1 as it does in many      
instances4 ,on this view1#i moreover1   
the cause of the reef springing  up at  
such a great distance from the land1    
leaving a deep and broad  moat within1  
remains altogether unexplained4 ,a      
supposition of the same  nature1 and    
appearing at first more probable is1    
that the reefs sprung  up from banks of 
sediment1 which had accumulated round   
the shore  previously to the growth of  
the coral2 but the extension of a bank  

to  the same distance round an unbroken 
coast1 and in front of those deep  arms 
of the sea 7as in ,raiatea1 see ,plate  
,,ii41 ,figure #c7 which  penetrate     
nearly to the heart of some encircled   
islands1 is exceedingly  improbable4    
,and why1 again1 should the reef spring 
up1 in some cases  steep on both sides  
like a wall1 at a distance of two1 three
 or more  miles from the shore1 leaving 
a channel often between two hundred and 
three hundred feet deep1 and rising from
 a depth which we have reason  to       
believe is destructive to the growth of 
coral8 ,an admission of this  nature    
cannot possibly be made4 ,the existence1
 also1 of the deep  channel1 utterly    
precludes the idea of the reef having   
grown outwards1  on a foundation slowly 
formed on its outside1 by the           
accumulation of  sediment and coral     
detritus4 ,nor1 again1 can it be        
asserted1 that the  reef-building corals
 will not grow1 excepting at a great    
distance from  the land2 for1 as we     

shall soon see1 there is a whole class  
of reefs1  which take their name from   
growing closely attached 7especially    
where  the sea is deep7 to the beach4   
,at ,new ,caledonia 7see ,plate ,,ii41  
,figure  #e7 the reefs which run in     
front of the west coast are prolonged in
 the  same line #aej miles beyond the   
northern extremity of the island1 and   
this shows that some explanation1 quite 
different from any of those  just       
suggested1 is required4 ,the            
continuation of the reefs on each side  
of the submarine prolongation of ,new   
,caledonia1 is an exceedingly           
interesting fact1 if this part formerly 
existed as the northern  extremity of   
the island1 and before the attachment of
 the coral had  been worn down by the   
action of the sea1 or if it originally  
existed at  its present height1 with or 
without beds of sediment on each flank1 
how  can we possibly account for the    
reefs1 not growing on the crest of this 
submarine portion1 but fronting its     

sides1 in the same line with the  reefs 
which front the shores of the lofty     
island8 ,we shall hereafter  see1 that  
there is one1 and ,i believe only one1  
solution of this  difficulty4     #h ,in
 the fifth chapter an east and west     
section across the ,island of           
,bolabola and its barrier-reefs is      
given1 for the sake of illustrating     
another point4 ,the unbroken line in it 
7woodcut ,no4 #e7 is the section        
referred to4 ,the scale is 4#eg of an   
inch to a mile2 it is taken from   the  
8,atlas of the ,voyage of the           
,coquille10 by ,duperrey4 ,the depth of 
the lagoon-channel is exaggerated4      
#i ,the ,rev4 ,d4 ,tyerman and ,mr4     
,bennett 78,journal of ,voyage and      
,travels10 volume i41 page #bae7 have   
briefly suggested this explanation   of 
the origin of the encircling reefs of   
the ,society ,islands4      ,one other  
supposition to account for the position 
of encircling  barrier-reefs remains1   
but it is almost too preposterous to be 

mentioned2 namely1 that they rest on    
enormous submarine craters1  surrounding
 the included islands4 ,when the size1  
height1 and form of  the islands in the 
,society group are considered1 together 
with the fact  that all are thus        
encircled1 such a notion will be        
rejected by almost  every one4 ,new     
,caledonia1 moreover1 besides its size1 
is composed of  primitive formations1 as
 are some of the ,comoro ,islands2#aj   
and  ,aitutaki consists of calcareous   
rock4 ,we must1 therefore1 reject these 
several explanations1 and conclude that 
the vertical thickness of               
barrier-reefs1 from their outer edges to
 the foundation on which they  rest     
7from ,,aa in the section to the dotted 
lines7 is really great2  but in this1   
there is no difficulty1 for it is not   
necessary to suppose  that the coral has
 sprung up from an immense depth1 as    
will be evident  when the theory of the 
upward growth of coral-reefs1 during the
 slow  subsidence of their foundation1  

is discussed4     #aj ,i have been      
informed that this is the case by ,dr4  
,allan of   ,forres1 who has visited    
this group4          ,,chapter ,,iii4   
,,fringing ,,or ,,shore-,,reefs4        
,reefs of ,mauritius4--,shallow channel 
within the reef4--,its slow filling     
up4--,currents of water formed within   
it4--,upraised reefs4--,narrow          
fringing-reefs in deep seas4--,reefs on 
the coast of ,east ,africa and of       
,brazil4--,fringing-reefs in very       
shallow seas1 round banks of sediment   
and on worn-down                        
islands4--,fringing-reefs affected by   
currents of the  sea4-- ,coral coating  
the bottom of the sea1 but not forming  
reefs4      ,fringing-reefs1 or1 as they
 have been called by some voyagers1     
shore-reefs1 whether skirting an island 
or part of a continent1 might  at first 
be thought to differ little1 except in  
generally being of less  breadth1 from  
barrier-reefs4 ,as far as the           
superficies of the actual  reef is      

concerned this is the case2 but the     
absence of an interior  deep-water      
channel1 and the close relation in their
 horizontal  extension with the probable
 slope beneath the sea of the adjoining 
land1 present essential points of       
difference4    ,the reefs which fringe  
the island of ,mauritius offer a good   
example of  this class4 ,they extend    
round its whole circumference1 with the 
exception of two or three parts1#a where
 the coast is almost  precipitous1 and  
where1 if as is probable the bottom of  
the sea has a  similar inclination1 the 
coral would have no foundation on which 
to  become attached4 ,a similar fact may
 sometimes be observed even in reefs  of
 the barrier class1 which follow much   
less closely the outline of the         
adjoining land2 as1 for instance1 on the
 south-east and precipitous  side of    
,tahiti1 where the encircling reef is   
interrupted4 ,on the  western side of   
the ,mauritius1 which was the only part 
,i visited1 the  reef generally lies at 

the distance of about half a mile from  
the  shore2 but in some parts it is     
distant from one to two1 and even three 
miles4 ,but even in this last case1 as  
the coast-land is gently inclined  from 
the foot of the mountains to the        
sea-beach1 and as the soundings  outside
 the reef indicate an equally gentle    
slope beneath the water1  there is no   
reason for supposing that the basis of  
the reef1 formed by  the prolongation of
 the strata of the island1 lies at a    
greater depth  than that at which the   
polypifers could begin constructing the 
reef4  ,some allowance1 however1 must be
 made for the outward extension of the  
corals on a foundation of sand and      
detritus1 formed from their own  wear1  
which would give to the reef a somewhat 
greater vertical  thickness1 than would 
otherwise be possible4     #a ,this fact
 is stated on the authority of the      
,officier du ,roi1 in   his extremely   
interesting 8,voyage  l',isle de        
,france10 undertaken in   #agfh4        

,according to ,captain ,carmichael      
7,hooker's 8,bot4 ,misc40 volume   ii41 
page #caf7 on one part of the coast     
there is a space for sixteen   miles    
without a reef4      ,the outer edge of 
the reef on the western or leeward side 
of the island  is tolerably well        
defined1 and is a little higher than any
 other part4  ,it chiefly consists of   
large strongly branched corals1 of the  
genus  ,madrepora1 which also form a    
sloping bed some way out to sea3 the    
kinds  of coral growing in this part    
will be described in the ensuing        
chapter4  ,between the outer margin and 
the beach1 there is a flat space with a 
sandy bottom and a few tufts of living  
coral2 in some parts it is so  shallow1 
that people1 by avoiding the deeper     
holes and gullies1 can  wade across it  
at low water2 in other parts it is      
deeper1 seldom  however exceeding ten or
 twelve feet1 so that it offers a safe  
coasting  channel for boats4 ,on the    
eastern and windward side of the island1

  which is exposed to a heavy surf1 the 
reef was described to me as  having a   
hard smooth surface1 very slightly      
inclined inwards1 just  covered at      
low-water1 and traversed by gullies2 it 
appears to be quite  similar in         
structure to the reefs of the barrier   
and atoll classes4    ,the reef of      
,mauritius1 in front of every river and 
streamlet1 is  breached by a straight   
passage3 at ,grand ,port1 however1 there
 is a  channel like that within a       
barrier-reef2 it extends parallel to the
  shore for four miles1 and has an      
average depth of ten or twelve  fathoms2
 its presence may probably be accounted 
for by two rivers which  enter at each  
end of the channel1 and bend towards    
each other4 ,the fact  of reefs of the  
fringing class being always breached in 
front of  streams1 even of those which  
are dry during the greater part of the  
year1 will be explained1 when the       
conditions unfavourable to the growth   
of coral are considered4 ,low           

coral-islets1 like those on             
barrier-reefs  and atolls1 are seldom   
formed on reefs of this class1 owing    
apparently  in some cases to their      
narrowness1 and in others to the gentle 
slope of  the reef outside not yielding 
many fragments to the breakers4 ,on the 
windward side1 however1 of the          
,mauritius1 two or three small islets   
have been formed4    ,it appears1 as    
will be shown in the ensuing chapter1   
that the action of  the surf is         
favourable to the vigorous growth of the
 stronger corals1  and that sand or     
sediment1 if agitated by the waves1 is  
injurious to  them4 ,hence it is        
probable that a reef on a shelving      
shore1 like that  of ,mauritius1 would  
at first grow up1 not attached to the   
actual beach1  but at some little       
distance from it2 and the corals on the 
outer margin  would be the most         
vigorous4 ,a shallow channel would thus 
be formed  within the reef1 and as the  
breakers are prevented acting on the    

shores  of the island1 and as they do   
not ordinarily tear up many fragments   
from the outside1 and as every streamlet
 has its bed prolonged in a  straight   
line through the reef1 this channel     
could be filled up only  very slowly    
with sediment4 ,but a beach of sand and 
of fragments of the  smaller kinds of   
coral seems1 in the case of ,mauritius1 
to be slowly  encroaching on the shallow
 channel4 ,on many shelving and sandy   
coasts1  the breakers tend to form a bar
 of sand a little way from the beach1   
with a slight increase of depth within  
it2 for instance1 ,captain  ,grey#b     
states that the west coast of           
,australia1 in latitude #bd1 is  fronted
 by a sand bar about two hundred yards  
in width1 on which there  is only two   
feet of water2 but within it the depth  
increases to two  fathoms4 ,similar     
bars1 more or less perfect1 occur on    
other coasts4 ,in  these cases ,i       
suspect that the shallow channel 7which 
no doubt during  storms is occasionally 

obliterated7 is scooped out by the      
flowing away  of the water thrown beyond
 the line1 on which the waves break with
 the  greatest force4 ,at ,pernambuco a 
bar of hard sandstone1#c which has the  
same external form and height as a      
coral-reef1 extends nearly parallel  to 
the coast2 within this bar currents1    
apparently caused by the water  thrown  
over it during the greater part of each 
tide1 run strongly1 and  are wearing    
away its inner wall4 ,from these facts  
it can hardly be  doubted1 that within  
most fringing-reefs1 especially within  
those lying  some distance from the     
land1 a return stream must carry away   
the water  thrown over the outer edge2  
and the current thus produced1 would    
tend  to prevent the channel being      
filled up with sediment1 and might even 
deepen it under certain circumstances4  
,to this latter belief ,i am led1  by   
finding that channels are almost        
universally present within the          
fringing-reefs of those islands which   

have undergone recent elevatory         
movements2 and this could hardly have   
been the case1 if the conversion  of the
 very shallow channel into land had not 
been counteracted to a  certain extent4 
#b ,captain ,grey's 8,journal of ,two   
,expeditions10 volume i4 page #cfi4     
#c ,i have described this singular      
structure in the 8,london and           
,edinburgh ,phil4 ,mag40 ,october #ahda4
      ,a fringing-reef1 if elevated in a
 perfect condition above the level of   
the sea1 ought to present the singular  
appearance of a broad dry moat  within a
 low mound4 ,the author#d of an         
interesting pedestrian tour  round the  
,mauritius1 seems to have met with a    
structure of this kind3  he says        
8,j'observai que l1 o la mer tale1      
indpendamment des rescifs  du large1 il 
y  terre une espce d'effoncement ou     
chemin couvert  naturel4 ,on y pourrait 
mettre du canon10 etc4 ,in another place
 he adds1  8,avant de passer le ,cap1 on
 remarque un gros banc de corail elv de 

plus de quinze pieds3 c'est une espce de
 rescif1 que la mer abandonn1  il regne 
au pied une longue flaque d'eau1 dont on
 pourrait faire un  bassin pour de      
petits vaisseaux40 ,but the margin of   
the reef1 although  the highest and most
 perfect part1 from being most exposed  
to the surf1  would generally during a  
slow rise of the land be either         
partially or  entirely worn down to that
 level1 at which corals could renew     
their  growth on its upper edge4 ,on    
some parts of the coast-land of         
,mauritius  there are little hillocks of
 coral-rock1 which are either the last  
remnants of a continuous reef1 or of low
 islets formed on it4 ,i  observed that 
two such hillocks between ,tamarin ,bay 
and the ,great ,black  ,river2 they were
 nearly twenty feet high1 about two     
hundred yards from  the present beach1  
and about thirty feet above its level4  
,they rose  abruptly from a smooth      
surface1 strewed with worn fragments of 
coral4  ,they consisted in their lower  

part of hard calcareous sandstone1 and  
in  their upper of great blocks of      
several species of ,astra and           
,madrepora1  loosely aggregated2 they   
were divided into irregular beds1       
dipping  seaward1 in one hillock at an  
angle of #h1 and in the other at #ah ,i 
suspect that the superficial parts of   
the reefs1 which have been  upraised    
together with the islands they fringe1  
have generally been  much more modified 
by the wearing action of the sea1 than  
those of  ,mauritius4     #d 8,voyage   
l',isle de ,france1 par un ,officier du 
,roi10 part i41   pages #aib1 #bjj4     
,many islands#e are fringed by reefs    
quite similar to those of  ,mauritius2  
but on coasts where the sea deepens very
 suddenly the reefs  are much narrower1 
and their limited extension seems       
evidently to  depend on the high        
inclination of the submarine slope2 a   
relation1  which1 as we have seen1 does 
not exist in reefs of the barrier class4
  ,the fringing-reefs on steep coasts   

are frequently not more than from  fifty
 to one hundred yards in width2 they    
have a nearly smooth1 hard  surface1    
scarcely uncovered at low water1 and    
without any interior  shoal channel1    
like that within those fringing-reefs1  
which lie at a  greater distance from   
the land4 ,the fragments torn up during 
gales from  the outer margin are thrown 
over the reef on the shores of the      
island4  ,i may give as instances1      
,wateeo1 where the reef is described by 
,cook as  being a hundred yards wide2   
and ,mauti and ,elizabeth ,islands1#f   
where  it is only fifty yards in width3 
the sea round these islands is very     
deep4     #e ,i may give ,cuba1 as      
another instance2 ,mr4 ,taylor          
7,loudon's ,mag4 of   ,nat4 ,hist4      
volume ix41 page #ddi7 has described a  
reef several miles in   length between  
,gibara and ,vjaro1 which extends       
parallel to the shore   at the distance 
of between half and the third part of a 
mile1 and   encloses a space of shallow 

water1 with a sandy bottom and tufts of 
coral4 ,outside the edge of the reef1   
which is formed of great   branching    
corals1 the depth is six and seven      
fathoms4 ,this coast has   been upheaved
 at no very distant geological period40 
#f ,mauti is described by ,lord ,byron  
in the voyage of ,h4,m4,s4 ,blonde1     
and ,elizabeth ,island by ,captain      
,beechey4      ,fringing-reefs1 like    
barrier-reefs1 both surround islands1   
and front  the shores of continents4 ,in
 the charts of the eastern coast of     
,africa1  by ,captain ,owen1 many       
extensive fringing-reefs are laid down2 
thus1 for  a space of nearly forty      
miles1 from latitude #a #ae to #a #de   
,s41 a  reef fringes the shore at an    
average distance of rather more than one
  mile1 and therefore at a greater      
distance than is usual in reefs of  this
 class2 but as the coast-land is not    
lofty1 and as the bottom  shoals very   
gradually 7the depth being only from    
eight to fourteen  fathoms at a mile and

 a half outside the reef71 its extension
 thus far  from the land offers no      
difficulty4 ,the external margin of this
 reef is  described1 as formed of       
projecting points1 within which there is
 a  space1 from six to twelve feet deep1
 with patches of living coral on  it4   
,at ,mukdeesha 7latitude #b #a ,n47 8the
 port is formed10 it is  said1#g 8by a  
long reef extending eastward1 four or   
five miles1 within  which there is a    
narrow channel1 with ten to twelve feet 
of water at  low spring-tides20 it lies 
at the distance of a quarter of a mile  
from  the shore4 ,again1 in the plan of 
,mombas 7latitude #d ,s471 a reef       
extends for thirty-six miles1 at the    
distance of from half a mile to  one    
mile and a quarter from the shore2      
within it1 there is a channel  navigable
 8for canoes and small craft10 between  
six and fifteen feet  deep3 outside the 
reef the depth is about thirty fathoms  
at the  distance of nearly half a mile4 
,part of this reef is very symmetrical1 

and has a uniform breadth of two hundred
 yards4     #g ,owen's 8,africa10 volume
 i41 page #ceg1 from which work the     
foregoing facts are likewise taken4     
,the coast of ,brazil is in many parts  
fringed by reefs4 ,of these1 some  are  
not of coral formation2 for instance1   
those near ,bahia and in front  of      
,pernambuco2 but a few miles south of   
this latter city1 the reef  follows#h so
 closely every turn of the shore1 that  
,i can hardly doubt  it is of coral2 it 
runs at the distance of three-quarters  
of a mile  from the land1 and within it 
the depth is from ten to fifteen feet4  
,i  was assured by an intelligent pilot 
that at ,ports ,frances and ,maceio1    
the outer part of the reef consists of  
living coral1 and the inner of a  white 
stone1 full of large irregular cavities1
 communicating with the  sea4 ,the      
bottom of the sea off the coast of      
,brazil shoals gradually to  between    
thirty and forty fathoms1 at the        
distance of between nine and  ten       

leagues from the land4     #h ,see      
,baron ,roussin's 8,pilote du ,brsil10  
and accompanying   hydrographical       
memoir4      ,from the description now  
given1 we must conclude that the        
dimensions  and structure of            
fringing-reefs depend entirely on the   
greater or less  inclination of the     
submarine slope1 conjoined with the fact
 that  reef-building polypifers can     
exist only at limited depths4 ,it       
follows  from this1 that where the sea  
is very shallow1 as in the ,persian     
,gulf  and in parts of the ,east ,indian
 ,archipelago1 the reefs lose their     
fringing character1 and appear as       
separate and irregularly scattered      
patches1 often of considerable area4    
,from the more vigorous growth of  the  
coral on the outside1 and from the      
conditions being less favourable  in    
several respects within1 such reefs are 
generally higher and more  perfect in   
their marginal than in their central    
parts2 hence these  reefs sometimes     

assume 7and this circumstance ought not 
to be  overlooked7 the appearance of    
atolls2 but they differ from atolls in  
their central expanse being much less   
deep1 in their form being less  defined1
 and in being based on a shallow        
foundation4 ,but when in a deep  sea    
reefs fringe banks of sediment1 which   
have accumulated beneath the  surface1  
round either islands or submerged rocks1
 they are  distinguished with difficulty
 on the one hand from encircling        
barrier-reefs1 and on the other from    
atolls4 ,in the ,west ,indies there  are
 reefs1 which ,i should probably have   
arranged under both these  classes1 had 
not the existence of large and level    
banks1 lying a little  beneath the      
surface1 ready to serve as the basis for
 the attachment of  coral1 been         
occasionally brought into view by the   
entire or partial  absence of reefs on  
them1 and had not the formation of such 
banks1  through the accumulation of     
sediment now in progress1 been          

sufficiently  evident4 ,fringing-reefs  
sometimes coat1 and thus protect the    
foundations of islands1 which have been 
worn down by the surf to the  level of  
the sea4 ,according to ,ehrenberg1 this 
has been extensively the  case with the 
islands in the ,red ,sea1 which formerly
 ranged parallel to  the shores of the  
mainland1 with deep water within them3  
hence the  reefs now coating their bases
 are situated relatively to the land    
like  barrier-reefs1 although not       
belonging to that class2 but there are1 
as  ,i believe1 in the ,red ,sea some   
true barrier-reefs4 ,the reefs of this  
sea and of the ,west ,indies will be    
described in the ,appendix4 ,in some    
cases1 fringing-reefs appear to be      
considerably modified in outline by  the
 course of the prevailing currents4 ,dr4
 ,j4 ,allan informs me that on  the east
 coast of ,madagascar almost every      
headland and low point of  sand has a   
coral-reef extending from it in a ,s4,w4
 and ,n4,e4 line1  parallel to the      

currents on that shore4 ,i should think 
the influence of  the currents chiefly  
consisted in causing an extension1 in a 
certain  direction1 of a proper         
foundation for the attachment of the    
coral4  ,round many intertropical       
islands1 for instance the ,abrolhos on  
the  coast of ,brazil surveyed by       
,captain ,fitzroy1 and1 as ,i am        
informed by  ,mr4 ,cuming1 round the    
,philippines1 the bottom of the sea is  
entirely  coated by irregular masses of 
coral1 which although often of large    
size1 do not reach the surface and form 
proper reefs4 ,this must be  owing1     
either to insufficient growth1 or to the
 absence of those kinds  of corals which
 can withstand the breaking of the      
waves4    ,the three classes1           
atoll-formed1 barrier1 and              
fringing-reefs1 together  with the      
modifications just described of the     
latter1 include all the  most remarkable
 coral formations anywhere existing4 ,at
 the commencement  of the last chapter  

in the volume1 where ,i detail the      
principles on  which the map 7,plate    
,,iii47 is coloured1 the exceptional    
cases will be  enumerated4              
,,chapter ,,iv4    ,,on ,,the           
,,distribution ,,and ,,growth ,,of      
,,coral-,,reefs4      ,in this chapter  
,i will give all the facts which ,i have
 collected1  relating to the            
distribution of coral-reefs1--to the    
conditions  favourable to their         
increase1--to the rate of their         
growth1--and to the  depth at which they
 are formed4    ,these subjects have an 
important bearing on the theory of the  
origin of  the different classes of     
coral-reefs4    ,,section ,i4--,,on     
,,the ,,distribution ,,of               
,,coral-,,reefs1 ,,and ,,on ,,the       
,,conditions  ,,favourable ,,to ,,their 
,,increase4    ,with regard to the      
limits of latitude1 over which          
coral-reefs extend1 ,i  have nothing new
 to add4 ,the ,bermuda ,islands1 in #cb 
#ae ,n41 is the  point furthest removed 

from the equator1 in which they appear  
to exist2  and it has been suggested    
that their extension so far northward in
 this  instance is owing to the warmth  
of the ,gulf ,stream4 ,in the ,pacific1 
the  ,loo ,choo ,islands1 in latitude   
#bg ,n41 have reefs on their shores1 and
  there is an atoll in #bh #cj1 situated
 ,n4,w4 of the ,sandwich  ,archipelago4 
,in the ,red ,sea there are coral-reefs 
in latitude #cj4 ,in  the southern      
hemisphere coral-reefs do not extend so 
far from the  equatorial sea4 ,in the   
,southern ,pacific there are only a few 
reefs  beyond the line of the tropics1  
but ,houtmans ,abrolhos1 on the western 
shores of ,australia in latitude #bi    
,s41 are of coral formation4    ,the    
proximity of volcanic land1 owing to the
 lime generally evolved  from it1 has   
been thought to be favourable to the    
increase of  coral-reefs4 ,there is1    
however1 not much foundation for this   
view2 for  nowhere are coral-reefs more 
extensive than on the shores of ,new    

,caledonia1 and of north-eastern        
,australia1 which consist of primary    
formations2 and in the largest groups of
 atolls1 namely the ,maldiva1  ,chagos1 
,marshall1 ,gilbert1 and ,low           
,archipelagoes1 there is no volcanic  or
 other kind of rock1 excepting that     
formed of coral4    ,the entire absence 
of coral-reefs in certain large areas   
within the  tropical seas1 is a         
remarkable fact4 ,thus no coral-reefs   
were observed1  during the surveying    
voyages of the 8,beagle0 and her tender 
on the west  coast of ,south ,america   
south of the equator1 or round the      
,galapagos  ,islands4 ,it appears1 also1
 that there are none#a north of the     
equator2  ,mr4 ,lloyd1 who surveyed the 
,isthmus of ,panama1 remarked to me1    
that  although he had seen corals living
 in the ,bay of ,panama1 yet he had     
never observed any reefs formed by them4
 ,i at first attributed this  absence of
 reefs on the coasts of ,peru and of the
 ,galapagos ,islands1#b  to the coldness

 of the currents from the south1 but the
 ,gulf of ,panama  is one of the hottest
 pelagic districts in the world4#c ,in  
the central  parts of the ,pacific there
 are islands entirely free from reefs2  
in  some few of these cases ,i have     
thought that this was owing to recent   
volcanic action2 but the existence of   
reefs round the greater part of         
,hawaii1 one of the ,sandwich ,islands1 
shows that recent volcanic action  does 
not necessarily prevent their growth4   
#a ,i have been informed that this is   
the case1 by ,lieutenant ,ryder1        
,r4,n41 and others who have had ample   
opportunities for observation4       #b 
,the mean temperature of the surface sea
 from observations made by   the        
direction of ,captain ,fitzroy on the   
shores of the ,galapagos   ,islands1    
between the #afth of ,september and the 
#bjth of ,october1 #ahce1   was #fh     
,fahr4 ,the lowest temperature observed 
was #eh4e at the   south-west end of    
,albemarle ,island2 and on the west     

coast of this   island1 it was several  
times #fb and #fc4 ,the mean temperature
 of the   sea in the ,low ,archipelago  
of atolls1 and near ,tahiti1 from       
similar   observations made on board the
 ,beagle1 was 7although further from    
the equator7 #gg4e1 the lowest any day  
being #gf4e4 ,therefore we have   here a
 difference of #i4e in mean temperature1
 and #ah in extremes2 a   difference    
doubtless quite sufficient to affect the
 distribution of   organic beings in the
 two areas4       #c ,humboldt's        
8,personal ,narrative10 volume vii41    
page #dcd4      ,in the last chapter ,i 
stated that the bottom of the sea round 
some  islands is thickly coated with    
living corals1 which nevertheless do not
  form reefs1 either from insufficient  
growth1 or from the species not  being  
adapted to contend with the breaking    
waves4    ,i have been assured by       
several people1 that there are no       
coral-reefs on  the west coast of       
,africa1#d or round the islands in the  

,gulf of  ,guinea4 ,this perhaps may be 
attributed1 in part1 to the sediment    
brought down by the many rivers         
debouching on that coast1 and to the    
extensive mud-banks1 which line great   
part of it4 ,but the islands of  ,st4   
,helena1 ,ascension1 the ,cape ,verdes1 
,st4 ,paul's1 and ,fernando  ,noronha1  
are1 also1 entirely without reefs1      
although they lie far out  at sea1 are  
composed of the same ancient volcanic   
rocks1 and have the  same general form1 
with those islands in the ,pacific1 the 
shores of  which are surrounded by      
gigantic walls of coral-rock4 ,with the 
exception of ,bermuda1 there is not a   
single coral-reef in the central        
expanse of the ,atlantic ,ocean4 ,it    
will1 perhaps1 be suggested that the    
quantity of carbonate of lime in        
different parts of the sea1 may         
regulate the presence of reefs4 ,but    
this cannot be the case1 for at         
,ascension1 the waves charged to excess 
precipitate a thick layer of  calcareous

 matter on the tidal rocks2 and at ,st4 
,jago1 in the ,cape  ,verdes1 carbonate 
of lime not only is abundant on the     
shores1 but it  forms the chief part of 
some upraised post-tertiary strata4 ,the
  apparently capricious distribution1   
therefore1 of coral-reefs1 cannot  be   
explained by any of these obvious       
causes2 but as the study of the         
terrestrial and better known half of the
 world must convince every one  that no 
station capable of supporting life is   
lost1--nay more1 that  there is a       
struggle for each station1 between the  
different orders of  nature1--we may    
conclude that in those parts of the     
intertropical sea1  in which there are  
no coral-reefs1 there are other organic 
bodies  supplying the place of the      
reef-building polypifers4 ,it has been  
shown  in the chapter on ,keeling atoll 
that there are some species of large    
fish1 and the whole tribe of ,holothuri 
which prey on the tenderer  parts of the
 corals4 ,on the other hand1 the        

polypifers in their turn  must prey on  
some other organic beings2 the decrease 
of which from any  cause would cause a  
proportionate destruction of the living 
coral4 ,the  relations1 therefore1 which
 determine the formation of reefs on any
  shore1 by the vigorous growth of the  
efficient kinds of coral1 must be  very 
complex1 and with our imperfect         
knowledge quite inexplicable4 ,from     
these considerations1 we may infer that 
changes in the condition of the  sea1   
not obvious to our senses1 might destroy
 all the coral-reefs in  one area1 and  
cause them to appear in another3 thus1  
the ,pacific or  ,indian ,ocean might   
become as barren of coral-reefs as the  
,atlantic now  is1 without our being    
able to assign any adequate cause for   
such a  change4     #d ,it might be     
concluded1 from a paper by ,captain     
,owen 78,geographical   ,journal01      
volume ii41 page #hi71 that the reefs   
off ,cape ,st4 ,anne and   the          
,sherboro' ,islands were of coral1      

although the author states that   they  
are not purely coralline4 ,but ,i have  
been assured by ,lieutenant   ,holland1 
,r4,n41 that these reefs are not of     
coral1 or at least that   they do not at
 all resemble those in the ,west        
,indies4      ,it has been a question   
with some naturalists1 which part of a  
reef is  most favourable to the growth  
of coral4 ,the great mounds of living   
,porites and of ,millepora round        
,keeling atoll occur exclusively on the 
extreme verge of the reef1 which is     
washed by a constant succession of      
breakers2 and living coral nowhere else 
forms solid masses4 ,at the  ,marshall  
islands the larger kinds of coral       
7chiefly species of ,astra1  a genus    
closely allied to ,porites7 8which form 
rocks measuring several  fathoms in     
thickness10 prefer1 according to        
,chamisso1#e the most  violent surf4 ,i 
have stated that the outer margin of the
 ,maldiva atolls  consists of living    
corals 7some of which1 if not all1 are  

of the same  species with those at      
,keeling atoll71 and here the surf is so
  tremendous1 that even large ships have
 been thrown1 by a single heave  of the 
sea1 high and dry on the reef1 all on   
board thus escaping with  their lives4  
#e ,kotzebue's 8,first ,voyage0         
7,english ,translation7 volume iii41    
pages   #adb1 #adc1 #cca4               
,ehrenberg#f remarks1 that in the ,red  
,sea the strongest corals live on  the  
outer reefs1 and appear to love the     
surf2 he adds1 that the more  branched  
kinds abound a little way within1 but   
that even these in still  more protected
 places1 become smaller4 ,many other    
facts having a  similar tendency might  
be adduced4#g ,it has1 however1 been    
doubted by  ,,mm4 ,quoy and ,gaimard1   
whether any kind of coral can even      
withstand1  much less flourish in1 the  
breakers of an open sea3#h they affirm  
that  the saxigenous lithophytes        
flourish only where the water is        
tranquil1  and the heat intense4 ,this  

statement has passed from one geological
  work to another2 nevertheless1 the    
protection of the whole reef            
undoubtedly is due to those kinds of    
coral1 which cannot exist in the        
situations thought by these naturalists 
to be most favourable to them4  ,for    
should the outer and living margin      
perish1 of any one of the many  low     
coral-islands1 round which a line of    
great breakers is incessantly  foaming1 
the whole1 it is scarcely possible to   
doubt1 would be washed  away and        
destroyed1 in less than half a century4 
,but the vital energies  of the corals  
conquer the mechanical power of the     
waves2 and the large  fragments of reef 
torn up by every storm1 are replaced by 
the slow but  steady growth of the      
innumerable polypifers1 which form the  
living zone  on its outer edge4     #f  
,ehrenberg1 8ber die ,natr und ,bildung 
der ,corallen ,bnke im   rothen ,meere10
 page #di4       #g ,in the ,west       
,indies1 as ,i am informed by ,captain  

,bird ,allen1 ,r4,n41   it is the common
 belief of those1 who are best          
acquainted with the   reefs1 that the   
coral flourishes most1 where freely     
exposed to the   swell of the open sea4 
#h 8,annales des ,sciences ,naturelles10
 tome vi41 pages #bgf1 #bgh4--8,l   o   
les ondes sont agites1 les ,lytophyts ne
 peuvent travailler1 parce   qu'elles   
dtruiraient leurs fragiles difices10 c4 
,from these facts1 it is certain1 that  
the strongest and most massive  corals  
flourish1 where most exposed4 ,the less 
perfect state of the reef  of most      
atolls on the leeward and less exposed  
side1 compared with its  state to       
windward2 and the analogous case of the 
greater number of  breaches on the near 
sides of those atolls in the ,maldiva   
,archipelago1  which afford some        
protection to each other1 are obviously 
explained by  this circumstance4 ,if the
 question had been1 under what          
conditions the  greater number of       
species of coral1 not regarding their   

bulk and  strength1 were developed1 ,i  
should answer1--probably in the         
situations  described by ,,mm4 ,quoy and
 ,gaimard1 where the water is tranquil  
and the  heat intense4 ,the total number
 of species of coral in the             
circumtropical seas must be very great3 
in the ,red ,sea alone1 #abj  kinds1    
according to ,ehrenberg1#i have been    
observed4     #i ,ehrenberg1 8ber die   
,natr10 etc41 etc41 page #df4      ,the 
same author has observed that the recoil
 of the sea from a steep  shore is      
injurious to the growth of coral1       
although waves breaking over  a bank are
 not so4 ,ehrenberg also states1 that   
where there is much  sediment1 placed so
 as to be liable to be moved by the     
waves there is  little or no coral2 and 
a collection of living specimens placed 
by him  on a sandy shore died in the    
course of a few days4#aj ,an experiment1
  however1 will presently be related in 
which some large masses of living  coral
 increased rapidly in size1 after having

 been secured by stakes on  a sandbank4 
,that loose sediment should be injurious
 to the living  polypifers1 appears1 at 
first sight1 probable2 and accordingly1 
in  sounding off ,keeling atoll1 and 7as
 will hereafter be shown7 off           
,mauritius1 the arming of the lead      
invariably came up clean1 where the     
coral was growing vigorously4 ,this same
 circumstance has probably given  rise  
to a strange belief1 which1 according to
 ,captain ,owen1#aa is  general amongst 
the inhabitants of the ,maldiva atolls1 
namely that  corals have roots1 and     
therefore that if merely broken down to 
the  surface1 they grow up again2 but1  
if rooted out1 they are permanently     
destroyed4 ,by this means the           
inhabitants keep their harbours clear2  
and  thus the ,french ,governor of ,st4 
,mary's in ,madagascar1 8cleared out and
  made a beautiful little port at that  
place40 ,for it is probable that  sand  
would accumulate in the hollows formed  
by tearing out the corals1  but not on  

the broken and projecting stumps1 and   
therefore1 in the  former case1 the     
fresh growth of the coral might be thus 
prevented4     #aj ,ibid41 page #di4    
#aa ,captain ,owen on the ,geography of 
the ,maldiva ,islands1   8,geographical 
,journal01 volume ii41 page #hh4        
,in the last chapter ,i remarked that   
fringing-reefs are almost  universally  
breached1 where streams enter the       
sea4#ab ,most authors  have attributed  
this fact to the injurious effects of   
the fresh water1  even where it enters  
the sea only in small quantity1 and     
during a part  of the year4 ,no doubt   
brackish water would prevent or retard  
the growth  of coral2 but ,i believe    
that the mud and sand which is          
deposited1 even  by rivulets when       
flooded1 is a much more efficient check4
 ,the reef on  each side of the channel 
leading into ,port ,louis at ,mauritius1
 ends  abruptly in a wall1 at the foot  
of which ,i sounded and found a bed of  
thick mud4 ,this steepness of the sides 

appears to be a general  character in   
such breaches4 ,cook1#ac speaking of one
 at ,raiatea1 says1  8like all the rest1
 it is very steep on both sides40 ,now1 
if it were  the fresh water mingling    
with the salt which prevented the growth
 of  coral1 the reef certainly would not
 terminate abruptly1 but as the         
polypifers nearest the impure stream    
would grow less vigorously than  those  
farther off1 so would the reef gradually
 thin away4 ,on the other  hand1 the    
sediment brought down from the land     
would only prevent the  growth of the   
coral in the line of its deposition1 but
 would not check  it on the side1 so    
that the reefs might increase till they 
overhung the  bed of the channel4 ,the  
breaches are much fewer in number1 and  
front  only the larger valleys in reefs 
of the encircling barrier class4 ,they  
probably are kept open in the same      
manner as those into the lagoon of  an  
atoll1 namely1 by the force of the      
currents and the drifting  outwards of  

fine sediment4 ,their position in front 
of valleys1 although  often separated   
from the land by deep water             
lagoon-channels1 which it  might be     
thought would entirely remove the       
injurious effects both of  the fresh    
water and the sediment1 will receive a  
simple explanation  when we discuss the 
origin of barrier-reefs4     #ab        
,lieutenant ,wellstead and others have  
remarked that this is the   case in the 
,red ,sea2 ,dr4 ,rppell 78,reise in     
,abyss40 ,band4 i41 page   #adb7 says   
that there are pear-shaped harbours in  
the upraised   coral-coast1 into which  
periodical streams enter4 ,from this    
circumstance1 ,i presume1 we must infer 
that before the upheaval of the   strata
 now forming the coast-land1 fresh water
 and sediment entered   the sea at these
 points2 and the coral being thus       
prevented growing1   the pear-shaped    
harbours were produced4       #ac       
,cook's 8,first ,voyage10 volume ii41   
page #bga 7,hawkesworth's   edition747  

,in the vegetable kingdom every         
different station has its peculiar group
  of plants1 and similar relations      
appear to prevail with corals4 ,we have 
already described the great difference  
between the corals within the  lagoon of
 an atoll and those on its outer margin4
 ,the corals1 also1 on  the margin of   
,keeling ,island occurred in zones2 thus
 the ,porites and  ,millepora complanata
 grow to a large size only where they   
are washed  by a heavy sea1 and are     
killed by a short exposure to the air2  
whereas1  three species of ,nullipora   
also live amidst the breakers1 but are  
able  to survive uncovered for a part of
 each tide2 at greater depths1 a  strong
 ,madrepora and ,millepora alcicornis   
are the commonest kinds1  the former    
appearing to be confined to this part1  
beneath the zone of  massive corals1    
minute encrusting corallines and other  
organic bodies  live4 ,if we compare the
 external margin of the reef at ,keeling
 atoll  with that on the leeward side of

 ,mauritius1 which are very differently 
circumstanced1 we shall find a          
corresponding difference in the         
appearance of the corals4 ,at the latter
 place1 the genus ,madrepora is         
preponderant over every other kind1 and 
beneath the zone of massive  corals     
there are large beds of ,seriatopora4   
,there is also a marked  difference1    
according to ,captain ,moresby1#ad      
between the great  branching corals of  
the ,red ,sea1 and those on the reefs of
 the ,maldiva  atolls4     #ad ,captain 
,moresby on the ,northern ,maldiva      
atolls1 8,geographical   ,journal01     
volume v41 page #dja4      ,these facts1
 which in themselves are deserving of   
notice1 bear1  perhaps1 not very        
remotely1 on a remarkable circumstance  
which has been  pointed out to me by    
,captain ,moresby1 namely1 that with    
very few  exceptions1 none of the       
coral-knolls within the lagoons of      
,peros  ,banhos1 ,diego ,garcia1 and the
 ,great ,chagos ,bank 7all situated in  

the  ,chagos group71 rise to the surface
 of the water2 whereas all those1  with 
equally few exceptions1 within ,solomon 
and ,egmont atolls in the  same group1  
and likewise within the large southern  
,maldiva atolls1  reach the surface4 ,i 
make these statements1 after having     
examined the  charts of each atoll4 ,in 
the lagoon of ,peros ,banhos1 which is  
nearly  twenty miles across1 there is   
only one single reef which rises to the 
surface2 in ,diego ,garcia there are    
seven1 but several of these lie  close  
to the margin of the lagoon1 and need   
scarcely have been  reckoned2 in the    
,great ,chagos ,bank there is not one4  
,on the other hand1  in the lagoons of  
some of the great southern ,maldiva     
atolls1 although  thickly studded with  
reefs1 every one without exception rises
 to the  surface2 and on an average     
there are less than two submerged reefs 
in  each atoll2 in the northern atolls1 
however1 the submerged lagoon-reefs  are
 not quite so rare4 ,the submerged reefs

 in the ,chagos atolls  generally have  
from one to seven fathoms water on them1
 but some have  from seven to ten4 ,most
 of them are small with very steep      
sides2#ae at  ,peros ,banhos they rise  
from a depth of about thirty fathoms1   
and some  of them in the ,great ,chagos 
,bank from above forty fathoms2 they are
  covered1 ,captain ,moresby informs me1
 with living and healthy coral1 two  and
 three feet high1 consisting of several 
species4 ,why then have not  these      
lagoon-reefs reached the surface1 like  
the innumerable ones in  the atolls     
above named8 ,if we attempt to assign   
any difference in their  external       
conditions1 as the cause of this        
diversity1 we are at once  baffled4 ,the
 lagoon of ,diego ,garcia is not deep1  
and is almost wholly  surrounded by its 
reef2 ,peros ,banhos is very deep1 much 
larger1 with  many wide passages        
communicating with the open sea4 ,on the
 other hand1  of those atolls1 in which 
all or nearly all the lagoon-reefs have 

reached the surface1 some are small1    
others large1 some shallow1 others      
deep1 some well-enclosed1 and others    
open4     #ae ,some of these statements 
were not communicated to me verbally by 
,captain ,moresby1 but are taken from   
the ,,ms4 account before alluded to1    
of the ,chagos ,group4      ,captain    
,moresby informs me that he has seen a  
,french chart of ,diego  ,garcia made   
eighty years before his survey1 and     
apparently very  accurate2 and from it  
he infers1 that during this interval    
there has  not been the smallest change 
in the depth on any of the knolls within
  the lagoon4 ,it is also known that    
during the last fifty-one years1 the    
eastern channel into the lagoon has     
neither become narrower1 nor  decreased 
in depth2 and as there are numerous     
small knolls of living  coral within it1
 some change might have been            
anticipated4 ,moreover1 as  the whole   
reef round the lagoon of this atoll has 
been converted into  land--an           

unparalleled case1 ,i believe1 in an    
atoll of such large  size1--and as the  
strip of land is for considerable spaces
 more than  half a mile wide--also a    
very unusual circumstance1--we have the 
best  possible evidence1 that ,diego    
,garcia has remained at its present     
level  for a very long period4 ,with    
this fact1 and with the knowledge that  
no  sensible change has taken place     
during eighty years in the              
coral-knolls1 and considering that every
 single reef has reached the  surface in
 other atolls1 which do not present the 
smallest appearance  of being older than
 ,diego ,garcia and ,peros ,banhos1 and 
which are placed  under the same        
external conditions with them1 one is   
led to conclude  that these submerged   
reefs1 although covered with luxuriant  
coral1 have  no tendency to grow        
upwards1 and that they would remain at  
their  present levels for an almost     
indefinite period4    ,from the number  
of these knolls1 from their position1   

size1 and form1  many of them being only
 one or two hundred yards across1 with a
 rounded  outline1 and precipitous      
sides1--it is indisputable that they    
have been  formed by the growth of      
coral2 and this makes the case much more
  remarkable4 ,in ,peros ,banhos and in 
the ,great ,chagos ,bank1 some of these 
almost columnar masses are #bjj feet    
high1 and their summits lie only  from  
two to eight fathoms beneath the        
surface2 therefore1 a small             
proportional amount more of growth would
 cause them to attain the  surface1 like
 those numerous knolls1 which rise from 
an equally great  depth within the      
,maldiva atolls4 ,we can hardly suppose 
that time has  been wanting for the     
upward growth of the coral1 whilst in   
,diego  ,garcia1 the broad annular strip
 of land1 formed by the continued       
accumulation of detritus1 shows how long
 this atoll has remained at its  present
 level4 ,we must look to some other     
cause than the rate of  growth2 and ,i  

suspect it will be found in the reefs   
being formed of  different species of   
corals1 adapted to live at different    
depths4    ,the ,great ,chagos ,bank is 
situated in the centre of the ,chagos   
,group1  and the ,pitt and ,speaker     
,banks at its two extreme points4 ,these
 banks  resemble atolls1 except in their
 external rim being about eight fathoms 
submerged1 and in being formed of dead  
rock1 with very little living  coral on 
it3 a portion nine miles long of the    
annular reef of ,peros  ,banhos atoll is
 in the same condition4 ,these facts1 as
 will hereafter  be shown1 render it    
very probable that the whole group at   
some former  period subsided seven or   
eight fathoms2 and that the coral       
perished on  the outer margin of those  
atolls which are now submerged1 but that
 it  continued alive1 and grew up to the
 surface on those which are now         
perfect4 ,if these atolls did subside1  
and if from the suddenness of the       
movement or from any other cause1 those 

corals which are better adapted  to live
 at a certain depth than at the surface1
 once got possession of  the knolls1    
supplanting the former occupants1 they  
would exert little  or no tendency to   
grow upwards4 ,to illustrate this1 ,i   
may observe1 that  if the corals of the 
upper zone on the outer edge of ,keeling
 atoll were  to perish1 it is improbable
 that those of the lower zone would grow
 to  the surface1 and thus become       
exposed to conditions for which they do 
not appear to be adapted4 ,the          
conjecture1 that the corals on the      
submerged knolls within the ,chagos     
atolls have analogous habits with  those
 of the lower zone outside ,keeling     
atoll1 receives some support  from a    
remark by ,captain ,moresby1 namely1    
that they have a different  appearance  
from those on the reefs in the ,maldiva 
atolls1 which1 as we  have seen1 all    
rise to the surface3 he compares the    
kind of difference  to that of the      
vegetation under different climates4 ,i 

have entered at  considerable length    
into this case1 although unable to throw
 much light  on it1 in order to show    
that an equal tendency to upward growth 
ought  not to be attributed to all      
coral-reefs1--to those situated at      
different  depths1--to those forming the
 ring of an atoll or those on the knolls
  within a lagoon1--to those in one area
 and those in another4 ,the  inference1 
therefore1 that one reef could not grow 
up to the surface  within a given time1 
because another1 not known to be covered
 with the  same species of corals1 and  
not known to be placed under conditions 
exactly the same1 has not within the    
same time reached the surface1 is       
unsound4    ,,section ,,ii4--,,on ,,the 
,,rate ,,of ,,growth ,,of               
,,coral-,,reefs4    ,the remark made at 
the close of the last section1 naturally
 leads to  this division of our subject1
 which has not1 ,i think1 hitherto been 
considered under a right point of view4 
,ehrenberg#af has stated1 that  in the  

,red ,sea1 the corals only coat other   
rocks in a layer from one to  two feet  
in thickness1 or at most to a fathom and
 a half2 and he  disbelieves that1 in   
any case1 they form1 by their own proper
 growth1  great masses1 stratum over    
stratum4 ,a nearly similar observation  
has  been made by ,,mm4 ,quoy and       
,gaimard1#ag with respect to the        
thickness of  some upraised beds of     
coral1 which they examined at ,timor and
 some  other places4 ,ehrenberg#ah saw  
certain large massive corals in the ,red
  ,sea1 which he imagines to be of such 
vast antiquity1 that they might  have   
been beheld by ,pharaoh2 and according  
to ,mr4 ,lyell#ai there are  certain    
corals at ,bermuda1 which are known by  
tradition1 to have been  living for     
centuries4 ,to show how slowly          
coral-reefs grow upwards1  ,captain     
,beechey#bj has adduced the case of the 
,dolphin ,reef off  ,tahiti1 which has  
remained at the same depth beneath the  
surface1  namely about two fathoms and a

 half1 for a period of sixty-seven      
years4  ,there are reefs in the ,red    
,sea1 which certainly do not appear#ba  
to  have increased in dimensions during 
the last half-century1 and from the     
comparison of old charts with recent    
surveys1 probably not during the  last  
two hundred years4 ,these1 and other    
similar facts1 have so  strongly        
impressed many with the belief of the   
extreme slowness of the  growth of      
corals1 that they have even doubted the 
possibility of  islands in the great    
oceans having been formed by their      
agency4 ,others1  again1 who have not   
been overwhelmed by this difficulty1    
have admitted  that it would require    
thousands1 and tens of thousands of     
years1 to  form a mass1 even of         
inconsiderable thickness2 but the       
subject has not1  ,i believe1 been      
viewed in the proper light4     #af     
,ehrenberg1 as before cited1 pages #ci1 
#df1 and #ej4       #ag 8,annales des   
,sciences ,nat40 tom4 vi41 page #bh4    

#ah ,ehrenberg1 ut sup41 page #db4      
#ai ,lyell's 8,principles of ,geology10 
book iii41 chapter xviii4       #bj     
,beechey's 8,voyage to the ,pacific10   
chapter viii4       #ba ,ehrenberg1 ut  
sup41 page #dc4      ,that masses of    
considerable thickness have been formed 
by the growth of  coral1 may be inferred
 with certainty from the following      
facts4 ,in the  deep lagoons of ,peros  
,banhos and of the ,great ,chagos ,bank1
 there are1  as already described1 small
 steep-sided knolls covered with living 
coral4 ,there are similar knolls in the 
southern ,maldiva atolls1 some of       
which1 as ,captain ,moresby assures me1 
are less than a hundred yards in        
diameter1 and rise to the surface from a
 depth of between two hundred  and fifty
 and three hundred feet4 ,considering   
their number1 form1 and  position1 it   
would be preposterous to suppose that   
they are based on  pinnacles of any     
rock1 not of coral formation2 or that   
sediment could  have been heaped up into

 such small and steep isolated cones4   
,as no  kind of living coral grows above
 the height of a few feet1 we are       
compelled to suppose that these knolls  
have been formed by the  successive     
growth and death of many                
individuals1--first one being broken    
off or killed by some accident1 and then
 another1 and one set of  species being 
replaced by another set with different  
habits1 as the  reef rose nearer the    
surface1 or as other changes supervened4
 ,the  spaces between the corals would  
become filled up with fragments and     
sand1 and such matter would probably    
soon be consolidated1 for we learn  from
 ,lieutenant ,nelson1#bb that at        
,bermuda a process of this kind  takes  
place beneath water1 without the aid of 
evaporation4 ,in reefs1  also1 of the   
barrier class1 we may feel sure1 as ,i  
have shown1 that  masses of great       
thickness have been formed by the growth
 of the coral2  in the case of          
,vanikoro1 judging only from the depth  

of the moat  between the land and the   
reef1 the wall of coral-rock must be at 
least  three hundred feet in vertical   
thickness4     #bb 8,geological         
,transactions10 volume v41 page #aac4   
,it is unfortunate that the upraised    
coral-islands in the ,pacific have  not 
been examined by a geologist4 ,the      
cliffs of ,elizabeth ,island1 in  the   
,low ,archipelago1 are eighty feet high1
 and appear1 from ,captain  ,beechey's  
description1 to consist of a homogeneous
 coral-rock4 ,from the  isolated        
position of this island1 we may safely  
infer that it is an  upraised atoll1 and
 therefore that it has been formed by   
masses of  coral1 grown together4       
,savage ,island seems1 from the         
description of the  younger ,forster1#bc
 to have a similar structure1 and its   
shores are  about forty feet high3 some 
of the ,cook ,islands also appear#bd to 
be  similarly composed4 ,captain        
,belcher1 ,r4,n41 in a letter which     
,captain  ,beaufort showed me at the    

admiralty1 speaking of ,bow atoll1 says1
 8,i  have succeeded in boring          
forty-five feet through coral-sand1 when
 the  auger became jammed by the falling
 in of the surrounding creamy  matter40 
,on one of the ,maldiva atolls1 ,captain
 ,moresby bored to a depth  of          
twenty-six feet1 when his auger also    
broke3 he has had the kindness  to give 
me the matter brought up2 it is         
perfectly white1 and like  finely       
triturated coral-rock4     #bc          
,forster's 8,voyage round the ,world    
with ,cook10 volume ii41 pages   #afc1  
#afg4       #bd ,williams's 8,narrative 
of ,missionary ,enterprise10 page #cj4  
,in my description of ,keeling atoll1 ,i
 have given some facts1 which show  that
 the reef probably has grown outwards2  
and ,i have found1 just  within the     
outer margin1 the great mounds of       
,porites and of ,millepora1  with their 
summits lately killed1 and their sides  
subsequently  thickened by the growth of
 the coral3 a layer1 also1 of ,nullipora

 had  already coated the dead surface4  
,as the external slope of the reef is   
the same round the whole of this atoll1 
and round many other atolls1  the angle 
of inclination must result from an      
adaption between the  growing powers of 
the coral1 and the force of the         
breakers1 and their  action on the loose
 sediment4 ,the reef1 therefore1 could  
not increase  outwards1 without a nearly
 equal addition to every part of the    
slope1  so that the original inclination
 might be preserved1 and this would     
require a large amount of sediment1 all 
derived from the wear of corals  and    
shells1 to be added to the lower part4  
,moreover1 at ,keeling atoll1  and      
probably in many other cases1 the       
different kinds of corals would  have to
 encroach on each other2 thus the       
,nullipor cannot increase  outwards     
without encroaching on the ,porites and 
,millepora complanata1  as is now taking
 place2 nor these latter without        
encroaching on the  strongly branched   

,madreporet1 the ,millepora alcicornis1 
and some  ,astras2 nor these again      
without a foundation being formed for   
them  within the requisite depth1 by the
 accumulation of sediment4 ,how slow1   
then1 must be the ordinary lateral or   
outward growth of such reefs4 ,but  off 
,christmas atoll1 where the sea is much 
more shallow than is usual1  we have    
good reason to believe that1 within a   
period not very remote1  the reef has   
increased considerably in width4 ,the   
land has the  extraordinary breadth of  
three miles2 it consists of parallel    
ridges of  shells and broken corals1    
which furnish 8an incontestable proof10 
as  observed by ,cook1#be 8that the     
island has been produced by accessions  
from the sea1 and is in a state of      
increase40 ,the land is fronted by a    
coral-reef1 and from the manner in which
 islets are known to be formed1  we may 
feel confident that the reef was not    
three miles wide1 when the  first1 or   
most backward ridge1 was thrown up2 and1

 therefore1 we must  conclude that the  
reef has grown outwards during the      
accumulation of  the successive ridges4 
,here then1 a wall of coral-rock of very
  considerable breadth has been formed  
by the outward growth of the  living    
margin1 within a period during which    
ridges of shells and  corals1 lying on  
the bare surface1 have not decayed4     
,there can be  little doubt1 from the   
account given by ,captain ,beechey1 that
 ,matilda  atoll1 in the ,low           
,archipelago1 has been converted in the 
space of  thirty-four years1 from being1
 as described by the crew of a wrecked  
whaling vessel1 a 8reef of rocks0 into a
 lagoon-island1 fourteen miles  in      
length1 with 8one of its sides covered  
nearly the whole way with  high         
trees40#bf ,the islets1 also1 on        
,keeling atoll1 it has been shown1  have
 increased in length1 and since the     
construction of an old chart1  several  
of them have become united into one long
 islet2 but in this  case1 and in that  

of ,matilda atoll1 we have no proof1 and
 can only  infer as probable1 that the  
reef1 that is the foundation of the     
islets1  has increased as well as the   
islets themselves4     #be ,cook's      
8,third ,voyage10 book ,,iii41 chapter  
x4       #bf ,beechey's 8,voyage to the 
,pacific10 chapter vii4 and viii4       
,after these considerations1 ,i attach  
little importance1 as indicating  the   
ordinary and still less the possible    
rate of outward growth of  coral-reefs1 
to the fact that certain reefs in the   
,red ,sea have not  increased during a  
long interval of time2 or to other such 
cases1 as  that of ,ouluthy atoll in the
 ,caroline group1 where every islet1    
described a thousand years before by    
,cantova was found in the same  state by
 ,lutk1#bg--without it could be shown   
that1 in these cases1 the  conditions   
were favourable to the vigorous and     
unopposed growth of the  corals living  
in the different zones of depth1 and    
that a proper basis  for the extent of  

the reef was present4 ,the former       
conditions must  depend on many         
contingencies1 and in the deep oceans   
where coral  formations most abound1 a  
basis within the requisite depth can    
rarely  be present4     #bg ,f4 ,lutk's 
8,voyage autour du ,monde40 ,in the     
group ,elato1 however1   it appears that
 what is now the islet ,falipi1 is      
called in ,cantova's   ,chart1 the ,banc
 de ,falipi4 ,it is not stated whether  
this has been   caused by the growth of 
coral1 or by the accumulation of sand4  
,nor do ,i attach any importance to the 
fact of certain submerged reefs1  as    
those off ,tahiti1 or those within      
,diego ,garcia not now being nearer  the
 surface than they were many years ago1 
as an indication of the rate  under     
favourable circumstances of the upward  
growth of reefs2 after  it has been     
shown1 that all the reefs have grown to 
the surface in some  of the ,chagos     
atolls1 but that in neighbouring atolls 
which appear to  be of equal antiquity  

and to be exposed to the same external  
conditions1 every reef remains          
submerged2 for we are almost driven to  
attribute this to a difference1 not in  
the rate of growth1 but in the  habits  
of the corals in the two cases4    ,in  
an old-standing reef1 the corals1 which 
are so different in kind on  different  
parts of it1 are probably all adapted to
 the stations they  occupy1 and hold    
their places1 like other organic beings1
 by a struggle  one with another1 and   
with external nature2 hence we may infer
 that  their growth would generally be  
slow1 except under peculiarly           
favourable circumstances4 ,almost the   
only natural condition1 allowing a      
quick upward growth of the whole surface
 of a reef1 would be a slow  subsidence 
of the area in which it stood2 if1 for  
instance1 ,keeling  atoll were to       
subside two or three feet1 can we doubt 
that the  projecting margin of live     
coral1 about half an inch in thickness1 
which  surrounds the dead upper surfaces

 of the mounds of ,porites1 would in    
this case form a concentric layer over  
them1 and the reef thus increase        
upwards1 instead of1 as at present1     
outwards8 ,the ,nullipor are now        
encroaching on the ,porites and         
,millepora1 but in this case might we   
not  confidently expect that the latter 
would1 in their turn1 encroach on  the  
,nullipor8 ,after a subsidence of this  
kind1 the sea would gain on  the islets1
 and the great fields of dead but       
upright corals in the  lagoon1 would be 
covered by a sheet of clear water2 and  
might we not  then expect that these    
reefs would rise to the surface1 as they
  anciently did when the lagoon was less
 confined by islets1 and as they  did   
within a period of ten years in the     
schooner-channel1 cut by the            
inhabitants8 ,in one of the ,maldiva    
atolls1 a reef1 which within a very  few
 years existed as an islet bearing      
cocoa-nut trees1 was found by           
,lieutenant ,prentice 8entirely covered 

with live coral and ,madrepore40  ,the  
natives believe that the islet was      
washed away by a change in the          
currents1 but if1 instead of this1 it   
had quietly subsided1 surely  every part
 of the island which offered a solid    
foundation1 would in a  like manner have
 become coated with living coral4       
,through steps such as these1 any       
thickness of rock1 composed of a        
singular intermixture of various kinds  
of corals1 shells1 and  calcareous      
sediment1 might be formed2 but without  
subsidence1 the  thickness would        
necessarily be determined by the depth  
at which the  reef-building polypifers  
can exist4 ,if it be asked1 at what rate
 in  years ,i suppose a reef of coral   
favourably circumstanced could grow up  
from a given depth2 ,i should answer1   
that we have no precise evidence  on    
this point1 and comparatively little    
concern with it4 ,we see1 in            
innumerable points over wide areas1 that
 the rate has been sufficient1  either  

to bring up the reefs from various      
depths to the surface1 or1 as  is more  
probable1 to keep them at the surface1  
during progressive  subsidences2 and    
this is a much more important standard  
of comparison  than any cycle of years4 
,it may1 however1 be inferred from the  
following facts1 that the rate in  years
 under favourable circumstances would be
 very far from slow4 ,dr4  ,allan1 of   
,forres1 has1 in his ,,ms4 ,thesis      
deposited in the library of  the        
,edinburgh ,university 7extracts from   
which ,i owe to the kindness of  ,dr4   
,malcolmson71 the following account of  
some experiments1 which he  tried during
 his travels in the years #ahcj to #ahcb
 on the east coast of  ,madagascar4 8,to
 ascertain the rise and progress of the 
coral-family1  and fix the number of    
species met with at ,foul ,point        
7latitude #ag #dj7  twenty species of   
coral were taken off the reef and       
planted apart on a  sand-bank three feet
 deep at low water4 ,each portion       

weighed ten  pounds1 and was kept in its
 place by stakes4 ,similar quantities   
were  placed in a clump and secured as  
the rest4 ,this was done in ,december   
#ahcj4 ,in ,july following1 each        
detached mass was nearly level with the 
sea at low water1 quite immovable1 and  
several feet long1 stretching as  the   
parent reef1 with the coast current from
 north to south4 ,the masses            
accumulated in a clump were found       
equally increased1 but some of the      
species in such unequal ratios1 as to be
 growing over each other40 ,the  loss of
 ,dr4 ,allan's magnificent collection by
 shipwreck1 unfortunately  prevents its 
being known to what genera these corals 
belonged2 but from  the numbers         
experimented on1 it is certain that all 
the more  conspicuous kinds must have   
been included4 ,dr4 ,allan informs me1  
in a  letter1 that he believes it was a 
,madrepora1 which grew most  vigorously4
 ,one may be permitted to suspect that  
the level of the sea  might possibly    

have been somewhat different at the two 
stated periods2  nevertheless1 it is    
quite evident that the growth of the    
ten-pound  masses1 during the six or    
seven months1 at the end of which they  
were  found immovably fixed#bh and      
several feet in length1 must have been  
very great4 ,the fact of the different  
kinds of coral1 when placed in  one     
clump1 having increased in extremely    
unequal ratios1 is very  interesting1 as
 it shows the manner in which a reef1   
supporting many  species of coral1 would
 probably be affected by a change in the
  external conditions favouring one kind
 more than another4 ,the growth of  the 
masses of coral in ,n4 and ,s4 lines    
parallel to the prevailing  currents1   
whether due to the drifting of sediment 
or to the simple  movement of the water1
 is1 also1 a very interesting           
circumstance4     #bh ,it is stated by  
,de la ,beche 78,geological ,manual10   
page #adc71 on   the authority of ,mr4  
,lloyd1 who surveyed the ,isthmus of    

,panama1 that   some specimens of       
,polypifers1 placed by him in a         
sheltered pool of   water1 were found in
 the course of a few days firmly fixed  
by the   secretion of a stony matter1 to
 the bottom4      ,a fact1 communicated 
to me by ,lieutenant ,wellstead1 ,i4,n41
 in some  degree corroborates the result
 of ,dr4 ,allan's experiments3 it is1   
that  in the ,persian ,gulf a ship had  
her copper bottom encrusted in the      
course of twenty months with a layer of 
coral1 two feet in thickness1  which it 
required great force to remove1 when the
 vessel was docked3 it  was not         
ascertained to what order this coral    
belonged4 ,the case of the              
schooner-channel choked up with coral in
 an interval of less than ten  years1 in
 the lagoon of ,keeling atoll1 should be
 here borne in mind4 ,we  may also      
infer1 from the trouble which the       
inhabitants of the ,maldiva  atolls take
 to root out1 as they express it1 the   
coral-knolls from  their harbours1 that 

their growth can hardly be very slow4#bi
     #bi ,mr4 ,stutchbury 78,west of    
,england ,journal01 ,no4 ,i41 page #ej47
 has   described a specimen of          
,agaricia1 8weighing #b lbs4 #i oz41    
which   surrounds a species of oyster1  
whose age could not be more than two    
years1 and yet is completely enveloped  
by this dense coral40 ,i presume   that 
the oyster was living when the specimen 
was procured2 otherwise   the fact tells
 nothing4 ,mr4 ,stutchbury also mentions
 an anchor1 which   had become entirely 
encrusted with coral in fifty years2    
other cases1   however1 are recorded of 
anchors which have long remained amidst 
coral-reefs without having become       
coated4 ,the anchor of the ,beagle1   in
 #ahcb1 after having been down exactly  
one month at ,rio de ,janeiro1   was so 
thickly coated by two species of        
,tubularia1 that large spaces   of the  
iron were entirely concealed2 the tufts 
of this horny zoophyte   were between   
two and three inches in length4 ,it has 

been attempted to   compute1 but ,i     
believe erroneously1 the rate of growth 
of a reef1 from   the fact mentioned by 
,captain ,beechey1 of the ,chama gigas  
being   embedded in coral-rock4 ,but it 
should be remembered1 that some species 
of this genus invariably live1 both     
whilst young and old1 in cavities1      
which the animal has the power of       
enlarging with its growth4 ,i saw   many
 of these shells thus embedded in the   
outer 8flat0 of ,keeling   atoll1 which 
is composed of dead rock2 and therefore 
the cavities in   this case had no      
relation whatever with the growth of    
coral4 ,m4   ,lesson1 also1 speaking of 
this shell 7,partie ,zoolog4 8,voyage de
 la   #8,coquille'071 has remarked1 8que
 constamment ses valves taient   engags 
compltement dans la masse des           
,madrepores40      ,from the facts given
 in this section1 it may be concluded1  
first1 that  considerable thicknesses of
 rock have certainly been formed within 
the  present geological area by the     

growth of coral and the accumulation of 
its detritus2 and1 secondly1 that the   
increase of individual corals and  of   
reefs1 both outwards or horizontally and
 upwards or vertically1  under the      
peculiar conditions favourable to such  
increase1 is not slow1  when referred   
either to the standard of the average   
oscillations of  level in the earth's   
crust1 or to the more precise but less  
important  one of a cycle of years4     
,,section ,,iii4--,,on ,,the ,,depths   
,,at ,,which ,,reef-,,building          
,,polypifers ,,can ,,live4    ,i have   
already described in detail1 which might
 have appeared trivial1  the nature of  
the bottom of the sea immediately       
surrounding ,keeling  atoll2 and ,i will
 now describe with almost equal care the
 soundings off  the fringing-reefs of   
,mauritius4 ,i have preferred this      
arrangement1 for  the sake of grouping  
together facts of a similar nature4 ,i  
sounded with  the wide bell-shaped lead 
which ,captain ,fitzroy used at ,keeling

 ,island1  but my examination of the    
bottom was confined to a few miles of   
coast  7between ,port ,louis and ,tomb  
,bay7 on the leeward side of the island4
  ,the edge of the reef is formed of    
great shapeless masses of branching     
,madrepores1 which chiefly consist of   
two species1--apparently ,m4  corymbosa 
and pocillifera1-- mingled with a few   
other kinds of coral4  ,these masses are
 separated from each other by the most  
irregular  gullies and cavities1 into   
which the lead sinks many feet4 ,outside
 this  irregular border of ,madrepores1 
the water deepens gradually to twenty   
fathoms1 which depth generally is found 
at the distance of from half to         
three-quarters of a mile from the reef4 
,a little further out the depth  is     
thirty fathoms1 and thence the bank     
slopes rapidly into the depths  of the  
ocean4 ,this inclination is very gentle 
compared with that  outside ,keeling and
 other atolls1 but compared with most   
coasts it is  steep4 ,the water was so  

clear outside the reef1 that ,i could   
distinguish every object forming the    
rugged bottom4 ,in this part1 and  to a 
depth of eight fathoms1 ,i sounded      
repeatedly1 and at each cast  pounded   
the bottom with the broad lead1         
nevertheless the arming  invariably came
 up perfectly clean1 but deeply         
indented4 ,from eight to  fifteen       
fathoms a little calcareous sand was    
occasionally brought up1  but more      
frequently the arming was simply        
indented4 ,in all this space  the two   
,madrepores above mentioned1 and two    
species of ,astra1 with  rather large#cj
 stars1 seemed the commonest kinds2 and 
it must be  noticed that twice at the   
depth of fifteen fathoms1 the arming was
  marked with a clean impression of an  
,astra4 ,besides these lithophytes1     
some fragments of the ,millepora        
alcicornis1 which occurs in the same    
relative position at ,keeling ,island1  
were brought up2 and in the deeper      
parts there were large beds of a        

,seriatopora1 different from ,s4        
subulata1 but closely allied to it4 ,on 
the beach within the reef1 the  rolled  
fragments consisted chiefly of the      
corals just mentioned1 and of  a massive
 ,porites1 like that at ,keeling atoll1 
of a ,meandrina1  ,pocillopora          
verrucosa1 and of numerous fragments of 
,nullipora4 ,from  fifteen to twenty    
fathoms the bottom was1 with few        
exceptions1 either  formed of sand1 or  
thickly covered with ,seriatopora3 this 
delicate  coral seems to form at these  
depths extensive beds unmingled with any
  other kind4 ,at twenty fathoms1 one   
sounding brought up a fragment of       
,madrepora apparently ,m4 pocillifera1  
and ,i believe it is the same  species  
7for ,i neglected to bring specimens    
from both stations7 which  mainly forms 
the upper margin of the reef2 if so1 it 
grows in depths  varying from #j to #bj 
fathoms4 ,between #bj and #bc fathoms ,i
 obtained  several soundings1 and they  
all showed a sandy bottom1 with one     

exception at #cj fathoms1 when the      
arming came up scooped out1 as if by    
the margin of a large ,caryophyllia4    
,beyond #cc fathoms ,i sounded only     
once2 and from #hf fathoms1 at the      
distance of one mile and a third from   
the edge of the reef1 the arming brought
 up calcareous sand with a  pebble of   
volcanic rock4 ,the circumstance of the 
arming having  invariably come up quite 
clean1 when sounding within a certain   
number  of fathoms off the reefs of     
,mauritius and ,keeling atoll 7eight    
fathoms  in the former case1 and twelve 
in the latter7 and of its having always 
come up 7with one exception7 smoothed   
and covered with sand1 when the  depth  
exceeded twenty fathoms1 probably       
indicates a criterion1 by which  the    
limits of the vigorous growth of coral  
might in all cases be  readily          
ascertained4 ,i do not1 however1 suppose
 that if a vast number  of soundings    
were obtained round these islands1 the  
limit above  assigned would be found    

never to vary1 but ,i conceive the facts
 are  sufficient to show1 that the      
exceptions would be few4 ,the           
circumstance  of a gradual change1 in   
the two cases1 from a field of clean    
coral to  a smooth sandy bottom1 is far 
more important in indicating the depth  
at  which the larger kinds of coral     
flourish than almost any number of      
separate observations on the depth1 at  
which certain species have been  dredged
 up4 ,for we can understand the         
gradation1 only as a prolonged  struggle
 against unfavourable conditions4 ,if a 
person were to find the  soil clothed   
with turf on the banks of a stream of   
water1 but on going  to some distance on
 one side of it1 he observed the blades 
of grass  growing thinner and thinner1  
with intervening patches of sand1 until 
he  entered a desert of sand1 he would  
safely conclude1 especially if  changes 
of the same kind were noticed in other  
places1 that the  presence of the water 
was absolutely necessary to the         

formation of a  thick bed of turf3 so   
may we conclude1 with the same feeling  
of  certainty1 that thick beds of coral 
are formed only at small depths  beneath
 the surface of the sea4     #cj ,since 
the preceding pages were printed off1 ,i
 have received from   ,mr4 ,lyell a very
 interesting pamphlet1 entitled         
8,remarks upon ,coral   ,formations10   
etc41 by ,j4 ,couthouy1 ,boston1 ,united
 ,states1 #ahdb4 ,there   is a statement
 7page #f71 on the authority of the     
,rev4 ,j4 ,williams1   corroborating the
 remarks made by ,ehrenberg and ,lyell  
7page #ga of this   volume71 on the     
antiquity of certain individual corals  
in the ,red ,sea   and at ,bermuda2     
namely1 that at ,upolu1 one of the      
,navigator ,islands1   8particular      
clumps of coral are known to the        
fishermen by name1   derived from either
 some particular configuration or       
tradition   attached to them1 and handed
 down from time immemorial40 ,with      
respect   to the thickness of masses of 

coral-rock1 it clearly appears1 from the
   descriptions given by ,mr4 ,couthouy 
7pages #cd1 #eh7 that ,mangaia and      
,aurora ,islands are upraised atolls1   
composed of coral rock3 the level       
summit of the former is about three     
hundred feet1 and that of ,aurora       
,island is two hundred feet above the   
sea-level4      ,i have endeavoured to  
collect every fact1 which might either  
invalidate  or corroborate this         
conclusion4 ,captain ,moresby1 whose    
opportunities  for observation during   
his survey of the ,maldiva and ,chagos  
,archipelagoes have been unrivalled1    
informs me1 that the upper part or  zone
 of the steep-sided reefs1 on the inner 
and outer coasts of the  atolls in both 
groups1 invariably consists of coral1   
and the lower  parts of sand4 ,at seven 
or eight fathoms depth1 the bottom is   
formed1  as could be seen through the   
clear water1 of great living masses of  
coral1 which at about ten fathoms       
generally stand some way apart from     

each other1 with patches of white sand  
between them1 and at a little  greater  
depth these patches become united into a
 smooth steep slope1  without any coral4
 ,captain ,moresby1 also1 informs me in 
support of his  statement1 that he found
 only decayed coral on the ,padua ,bank 
7northern  part of the ,laccadive group7
 which has an average depth between     
twenty-five and thirty-five fathoms1 but
 that on some other banks in  the same  
group with only ten or twelve fathoms   
water on them 7for  instance1 the       
,tillacapeni bank71 the coral was       
living4    ,with regard to the          
coral-reefs in the ,red ,sea1 ,ehrenberg
 has the  following passage3--8,the     
living corals do not descend there into 
great  depths4 ,on the edges of islets  
and near reefs1 where the depth was     
small1 very many lived2 but we found no 
more even at six fathoms4 ,the          
pearl-fishers at ,yemen and ,massaua    
asserted that there was no coral  near  
the pearl-banks at nine fathoms depth1  

but only sand4 ,we were not  able to    
institute any more special              
researches40#ca ,i am1 however1  assured
 both by ,captain ,moresby and          
,lieutenant ,wellstead1 that in the     
more northern parts of the ,red ,sea1   
there are extensive beds of living      
coral at a depth of twenty-five fathoms1
 in which the anchors of their  vessels 
were frequently entangled4 ,captain     
,moresby attributes the less  depth1 at 
which the corals are able to live in the
 places mentioned by  ,ehrenberg1 to the
 greater quantity of sediment there2 and
 the  situations1 where they were       
flourishing at the depth of twenty-five 
fathoms1 were protected1 and the water  
was extraordinarily limpid4 ,on  the    
leeward side of ,mauritius where ,i     
found the coral growing at a  somewhat  
greater depth than at ,keeling atoll1   
the sea1 owing apparently  to its       
tranquil state1 was likewise very clear4
 ,within the lagoons of  some of the    
,marshall atolls1 where the water can be

 but little  agitated1 there are1       
according to ,kotzebue1 living beds of  
coral in  twenty-five fathoms4 ,from    
these facts1 and considering the manner 
in  which the beds of clean coral off   
,mauritius1 ,keeling ,island1 the       
,maldiva and ,chagos atolls1 graduated  
into a sandy slope1 it appears  very    
probable that the depth1 at which       
reef-building polypifers can  exist1 is 
partly determined by the extent of      
inclined surface1 which  the currents of
 the sea and the recoiling waves have   
the power to keep  free from sediment4  
#ca ,ehrenberg1 8ber die ,natr10 c41    
page #ej4      ,,mm4 ,quoy and          
,gaimard#cb believe that the growth of  
coral is confined  within very limited  
depths2 and they state that they never  
found any  fragment of an ,astra 7the   
genus they consider most efficient in   
forming reefs7 at a depth above         
twenty-five or thirty feet4 ,but we have
  seen that in several places the bottom
 of the sea is paved with massive       

corals at more than twice this depth2   
and at fifteen fathoms 7or twice  this  
depth7 off the reefs of ,mauritius1 the 
arming was marked with the  distinct    
impression of a living ,astra4          
,millepora alcicornis lives in  from #j 
to #ab fathoms1 and the genera          
,madrepora and ,seriatopora from #j  to 
#bj fathoms4 ,captain ,moresby has given
 me a specimen of ,sideropora  scabra   
7,porites of ,lamarck7 brought up alive 
from #ag fathoms4 ,mr4  ,couthouy#cc    
states that he has dredged up on the    
,bahama banks  considerable masses of   
,meandrina from #af fathoms1 and he has 
seen this  coral growing in #bj fathoms4
 ,a ,caryophyllia1 half an inch in      
diameter1  was dredged up alive from #hj
 fathoms off ,juan ,fernandez 7latitude 
#cc  ,s47 by ,captain ,p4,p4 ,king3#cd  
this is the most remarkable fact with   
which ,i am acquainted1 showing the     
depth at which a genus of corals  often 
found on reefs1 can exist4#ce ,we ought1
 however1 to feel less  surprise at this

 fact1 as ,caryophyllia alone of the    
lamelliform genera1  ranges far beyond  
the tropics2 it is found in ,zetland    
7,fleming's  8,british ,animals10 genus 
,caryophyllia47 in ,latitude #fj ,n4 in 
deep  water1 and ,i procured a small    
species from ,tierra del ,fuego in      
,latitude  #ec ,s4 ,captain ,beechey    
informs me1 that branches of pink and   
yellow  coral were frequently brought up
 from between twenty and twenty-five    
fathoms off the ,low atolls2 and        
,lieutenant ,stokes1 writing to me from 
the ,n4,w4 coast of ,australia1 says    
that a strongly branched coral was      
procured there from thirty fathoms2     
unfortunately it is not known to  what  
genera these corals belong4     #cb     
8,annales des ,sci4 ,nat40 tom4 vi4     
#cc 8,remarks on ,coral ,formations10   
page #ab4       #cd ,i am indebted to   
,mr4 ,stokes for having kindly          
communicated this   fact to me1 together
 with much other valuable information4  
#ce ,i will record in the form of a note

 all the facts that ,i have   been able 
to collect on the depths1 both within   
and without the   tropics1 at which     
those corals and corallines can live1   
which there is   no reason to suppose   
ever materially aid in the construction 
of a   reef4    ,,name ,,of ,,zoophyte  
,depth in fathoms     ,,country and ,s4 
,,latitude       ,,authority            
,,sertularia             #dj            
,cape ,horn #ff                 ,where  
none is given1                          
the observation is my own  ,,cellaria   
ditto                ,ditto             
,,cellaria1 ,a minute     #aij          
,keeling ,atoll1 #ab         scarlet    
encrusting  species found living        
,,cellaria1 ,an allied1   #dh           
,st ,cruz ,riv4 #ej    small stony      
sub-generic  form       ,a coral allied 
to      #dj                   ,cape     
,horn         ,,vincularia1 with eight  
rows of cells  ,,tubulipora1 near to    
#dj                   ,cape ,horn       
,t4 patina  ,,tubulipora1 near to    #id

                   ,east ,chiloe #dc    
,t4 patina  ,,cellepora1 several     #dj
                   ,cape ,horn          
species1 and allied  sub-generic forms  
,,cellepora1 several     #dj and #eg    
,chonos ,archipelago #de                
species1 and allied  sub-generic forms  
,,cellepora1 several     #dh            
,st ,cruz #ej         species1 and      
allied  sub-generic forms  ,,eschara    
#cj                   ,tierra del ,fuego
 #ec         ,,eschara                  
#dh                   ,st ,cruz ,r4 #ej 
,,retepora               #dj            
,cape ,horn         ,,retepora          
#ajj                  ,cape of ,good    
,hope #cd         ,quoy and ,gaimard1   
8,ann4 ,scien4 ,nat40 tome vi41 page    
#bhd4  ,,millepora1 a strong    #id and 
#cj            ,e4 ,chiloe #dc  coral   
with cylindrical  branches1 of a pink   
colour1 about two  inches high1         
resembling in the  form of its orifices 
,m4 aspera of ,lamarck  ,tierra del     
,fuego #ec         ,,coralium           

#abj                  ,barbary #cc ,n4  
,peyssonel in paper read to ,royal      
,society ,may #ageb4  ,,antipathes      
#af                   ,chonos #de       
,,gorgonia 7or an allied #afj           
,abrolhos on the               ,captain 
,beechey informed me of this fact in a  
letter4  form7                          
coast of ,brazil #ah      ,ellis 78,nat4
 ,hist4 of ,coralline10 page #if7 states
 that ,ombellularia was  procured in    
latitude #gi ,n4 sticking to a line from
 the depth of  #bcf fathoms2 hence this 
coral either must have been floating    
loose1 or  was entangled in stray line  
at the bottom4 ,off ,keeling atoll a    
compound  ,ascidia 7,sigillina7 was     
brought up from #ci fathoms1 and a piece
 of  sponge1 apparently living1 from    
#gj1 and a fragment of ,nullipora also  
apparently living from #ib fathoms4 ,at 
a greater depth than #ij fathoms  off   
this coral island1 the bottom was       
thickly strewed with joints of          
,halimeda and small fragments of other  

,nullipor1 but all dead4 ,captain  ,b4  
,allen1 ,r4,n41 informs me that in the  
survey of the ,west ,indies it was      
noticed that between the depth of #aj   
and #bjj fathoms1 the sounding lead     
very generally came up coated with the  
dead joints of a ,halimeda1 of  which he
 showed me specimens4 ,off ,pernambuco1 
in ,brazil1 in about  twelve fathoms1   
the bottom was covered with fragments   
dead and alive of  a dull red           
,nullipora1 and ,i infer from ,roussin's
 chart1 that a bottom  of this kind     
extends over a wide area4 ,on the beach1
 within the  coral-reefs of ,mauritius1 
vast quantities of fragments of         
,nullipor  were piled up4 ,from these   
facts it appears1 that these simply     
organized  bodies are amongst the most  
abundant productions of the sea47       
,although the limit of depth1 at which  
each particular kind of coral  ceases to
 exist1 is far from being accurately    
known2 yet when we bear  in mind the    
manner in which the clumps of coral     

gradually became  infrequent at about   
the same depth1 and wholly disappeared  
at a greater  depth than twenty fathoms1
 on the slope round ,keeling atoll1 on  
the  leeward side of the ,mauritius1 and
 at rather less depth1 both without  and
 within the atolls of the ,maldiva and  
,chagos ,archipelagoes2 and when  we    
know that the reefs round these islands 
do not differ from other  coral         
formations in their form and structure1 
we may1 ,i think1 conclude  that in     
ordinary cases1 reef-building polypifers
 do not flourish at  greater depths than
 between twenty and thirty fathoms4     
,it has been argued#cf that reefs may   
possibly rise from very great  depths   
through the means of small corals1 first
 making a platform for  the growth of   
the stronger kinds4 ,this1 however1 is  
an arbitrary  supposition3 it is not    
always remembered1 that in such cases   
there is  an antagonist power in action1
 namely1 the decay of organic bodies1   
when not protected by a covering of     

sediment1 or by their own rapid  growth4
 ,we have1 moreover1 no right to        
calculate on unlimited time for  the    
accumulation of small organic bodies    
into great masses4 ,every fact  in      
geology proclaims that neither the land1
 nor the bed of the sea  retain for     
indefinite periods the same level4 ,as  
well might it be  imagined that the     
,british ,seas would in time become     
choked up with beds  of oysters1 or that
 the numerous small corallines off the  
inhospitable  shores of ,tierra del     
,fuego would in time form a solid and   
extensive  coral-reef4     #cf 8,journal
 of the ,royal ,geographical ,society10 
#ahca1 page #bah4          ,,chapter ,v4
    ,,theory ,,of ,,the ,,formation ,,of
 ,,the ,,different ,,classes ,,of       
,,coral-,,reefs4      ,the atolls of the
 larger archipelagoes are not formed on 
submerged  craters1 or on banks of      
sediment4--,immense areas interspersed  
with  atolls4--,their subsidence4--,the 
effects of storms and earthquakes on    

atolls4--,recent changes in their       
state4--,the origin of barrier-reefs and
  of atolls4--,their relative           
forms4--,the step-formed ledges and     
walls round  the shores of some         
lagoons4--,the ring-formed reefs of the 
,maldiva  atolls4--,the submerged       
condition of parts or of the whole of   
some  annular reefs4--,the disseverment 
of large atolls4--,the union of atolls  
by  linear reefs4--,the ,great ,chagos  
,bank4--,objections from the area and   
amount of subsidence required by the    
theory1 considered4--,the probable      
composition of the lower parts of       
atolls4      ,the naturalists who have  
visited the ,pacific1 seem to have had  
their  attention riveted by the         
lagoon-islands1 or atolls1--those       
singular  rings of coral-land which rise
 abruptly out of the unfathomable       
ocean--and have passed over1 almost     
unnoticed1 the scarcely less  wonderful 
encircling barrier-reefs4 ,the theory   
most generally received  on the         

formation of atolls1 is that they are   
based on submarine  craters2 but where  
can we find a crater of the shape of    
,bow atoll1  which is five times as long
 as it is broad 7,plate ,i41 ,figure    
#d72 or  like that of ,menchikoff       
,island 7,plate ,,ii41 ,figure #c471    
with its three  loops1 together sixty   
miles in length2 or like ,rimsky        
,korsacoff1  narrow1 crooked1 and       
fifty-four miles long2 or like the      
northern  ,maldiva atolls1 made up of   
numerous ring-formed reefs1 placed on   
the  margin of a disc1--one of which    
discs is eighty-eight miles in length1  
and only from ten to twenty in breadth8 
,it is1 also1 not a little  improbable1 
that there should have existed as many  
craters of immense  size crowded        
together beneath the sea1 as there are  
now in some parts  atolls4 ,but this    
theory lies under a greater difficulty1 
as will be  evident1 when we consider on
 what foundations the atolls of the     
larger  archipelagoes rest3             

nevertheless1 if the rim of a crater    
afforded a  basis at the proper depth1  
,i am far from denying that a reef like 
a  perfectly characterised atoll might  
not be formed2 some such1 perhaps1  now 
exist2 but ,i cannot believe in the     
possibility of the greater  number      
having thus originated4    ,an earlier  
and better theory was proposed by       
,chamisso2#a he supposes  that as the   
more massive kinds of corals prefer the 
surf1 the outer  portions1 in a reef    
rising from a submarine basis1 would    
first reach  the surface and            
consequently form a ring4 ,but on this  
view it must be  assumed1 that in every 
case the basis consists of a flat bank2 
for if  it were conically formed1 like a
 mountainous mass1 we can see no reason 
why the coral should spring up from the 
flanks1 instead of from the  central and
 highest parts3 considering the number  
of the atolls in the  ,pacific and      
,indian ,oceans1 this assumption is very
 improbable4 ,as the  lagoons of atolls 

are sometimes even more than forty      
fathoms deep1 it  must1 also1 be assumed
 on this view1 that at a depth at which 
the waves  do not break1 the coral grows
 more vigorously on the edges of a bank 
than on its central part2 and this is an
 assumption without any  evidence in    
support of it4 ,i remarked1 in the third
 chapter1 that a  reef1 growing on a    
detached bank1 would tend to assume an  
atoll-like  structure2 if1 therefore1   
corals were to grow up from a bank1 with
 a  level surface some fathoms          
submerged1 having steep sides and being 
situated in a deep sea1 a reef not to be
 distinguished from an atoll1  might be 
formed3 ,i believe some such exist in   
the ,west ,indies4 ,but a  difficulty of
 the same kind with that affecting the  
crater theory1  runners1 as we shall    
presently see1 this view inapplicable to
 the  greater number of atolls4     #a  
,kotzebue's 8,first ,voyage10 volume    
iii41 page #cca4      ,no theory worthy 
of notice has been advanced to account  

for those  barrier-reefs1 which encircle
 islands of moderate dimensions4 ,the   
great  reef which fronts the coast of   
,australia has been supposed1 but       
without  any special facts1 to rest on  
the edge of a submarine precipice1      
extending parallel to the shore4 ,the   
origin of the third class or of         
fringing-reefs presents1 ,i believe1    
scarcely any difficulty1 and is  simply 
consequent on the polypifers not growing
 up from great depths1  and their not   
flourishing close to gently shelving    
beaches where the  water is often       
turbid4    ,what cause1 then1 has given 
to atolls and barrier-reefs their       
characteristic forms8 ,let us see       
whether an important deduction will  not
 follow from the consideration of these 
two circumstances1 first1  the          
reef-building corals flourishing only at
 limited depths2 and  secondly1 the     
vastness of the areas interspersed with 
coral-reefs and  coral-islets1 none of  
which rise to a greater height above the

 level of  the sea1 than that attained  
by matter thrown up by the waves and    
winds4  ,i do not make this latter      
statement vaguely2 ,i have carefully    
sought  for descriptions of every island
 in the intertropical seas2 and my task 
has been in some degree abridged by a   
map of the ,pacific1 corrected in  #ahcd
 by ,,mm4 ,d',urville and ,lottin1 in   
which the low islands are  distinguished
 from the high ones 7even from those    
much less than a  hundred feet in       
height7 by being written without a      
capital letter2 ,i  have detected a few 
errors in this map1 respecting the      
height of some  of the islands1 which   
will be noticed in the ,appendix1 where 
,i treat of  coral formations in        
geographical order4 ,to the ,appendix1  
also1 ,i must  refer for a more         
particular account of the data on which 
the statements  on the next page are    
grounded4 ,i have ascertained1 and      
chiefly from the  writings of ,cook1    
,kotzebue1 ,bellinghausen1 ,duperrey1   

,beechey1 and  ,lutk1 regarding the     
,pacific2 and from ,moresby#b with      
respect to the  ,indian ,ocean1 that in 
the following cases the term 8low       
island0  strictly means land of the     
height commonly attained by matter      
thrown up  by the winds and the waves of
 an open sea4 ,if we draw a line 7the   
plan  ,i have always adopted7 joining   
the external atolls of that part of the 
,low ,archipelago in which the islands  
are numerous1 the figure will be a      
pointed ellipse 7reaching from ,hood to 
,lazaref ,island71 of which the  longer 
axis is #hdj geographical miles1 and the
 shorter #dbj miles2 in  this space#c   
none of the innumerable islets united   
into great rings  rise above the stated 
level4 ,the ,gilbert group is very      
narrow1 and #cjj  miles in length4 ,in a
 prolonged line from this group1 at the 
distance  of #bdj miles1 is the         
,marshall ,archipelago1 the figure of   
which is an  irregular square1 one end  
being broader than the other2 its length

 is  #ebj miles1 with an average width  
of #bdj2 these two groups together are  
#a1jdj miles in length1 and all their   
islets are low4 ,between the  southern  
end of the ,gilbert and the northern end
 of ,low ,archipelago1  the ocean is    
thinly strewed with islands1 all of     
which1 as far as ,i  have been able to  
ascertain1 are low2 so that from nearly 
the southern  end of the ,low           
,archipelago1 to the northern end of the
 ,marshall  ,archipelago1 there is a    
narrow band of ocean1 more than #d1jjj  
miles in  length1 containing a great    
number of islands1 all of which are low4
 ,in  the western part of the ,caroline 
,archipelago1 there is a space of #dhj  
miles in length1 and about #ajj broad1  
thinly interspersed with low  islands4  
,lastly1 in the ,indian ,ocean1 the     
archipelago of the ,maldivas  is #dgj   
miles in length1 and #fj in breadth2    
that of the ,laccadives is  #aej by #ajj
 miles2 as there is a low island between
 these two groups1  they may be         

considered as one group of #a1jjj miles 
in length4 ,to this  may be added the   
,chagos group of low islands1 situated  
#bhj miles  distant1 in a line prolonged
 from the southern extremity of the     
,maldivas4 ,this group1 including the   
submerged banks1 is #agj miles in       
length and #hj in breadth4 ,so striking 
is the uniformity in direction of  these
 three archipelagoes1 all the islands of
 which are low1 that  ,captain ,moresby1
 in one of his papers1 speaks of them as
 parts of one  great chain1 nearly      
#a1ejj miles long4 ,i am1 then1 fully   
justified in  repeating1 that enormous  
spaces1 both in the ,pacific and ,indian
 ,oceans1  are interspersed with        
islands1 of which not one rises above   
that  height1 to which the waves and    
winds in an open sea can heap up matter4
     #b ,see also ,captain ,owen's and  
,lieutenant ,wood's papers in the       
8,geographical ,journal01 on the        
,maldiva and ,laccadive ,archipelagoes4 
,these officers particularly refer to   

the lowness of the islets2 but ,i       
chiefly ground my assertion respecting  
these two groups1 and the   ,chagos     
group1 from information communicated to 
me by ,captain ,moresby4       #c ,i    
find from ,mr4 ,couthouy's pamphlet     
7page #eh7 that ,aurora ,island   is    
about two hundred feet in height2 it    
consists of coral-rock1 and   seems to  
have been formed by the elevation of an 
atoll4 ,it lies   north-east of ,tahiti1
 close without the line bounding the    
space   coloured dark blue in the map   
appended to this volume4 ,honden        
,island1   which is situated in the     
extreme north-west part of the ,low     
,archipelago1 according to measurements 
made on board the ,beagle1   whilst     
sailing by1 is #aad feet from the summit
 of the trees to the   water's edge4    
,this island appeared to resemble the   
other atolls of the   group4      ,on   
what foundations1 then1 have these reefs
 and islets of coral been  constructed8 
,a foundation must originally have been 

present beneath  each atoll at that     
limited depth1 which is indispensable   
for the first  growth of the            
reef-building polypifers4 ,a conjecture 
will perhaps be  hazarded1 that the     
requisite bases might have been afforded
 by the  accumulation of great banks of 
sediment1 which owing to the action of  
superficial currents 7aided possibly by 
the undulatory movement of the  sea7 did
 not quite reach the surface1--as       
actually appears to have been  the case 
in some parts of the ,west ,indian ,sea4
 ,but in the form and  disposition of   
the groups of atolls1 there is nothing  
to countenance  this notion2 and the    
assumption without any proof1 that a    
number of  immense piles of sediment    
have been heaped on the floor of the    
great  ,pacific and ,indian ,oceans1 in 
their central parts far remote from     
land1  and where the dark blue colour of
 the limpid water bespeaks its purity1  
cannot for one moment be admitted4      
,the many widely-scattered atolls must1 

therefore1 rest on rocky bases4  ,but we
 cannot believe that the broad summit of
 a mountain lies buried  at the depth of
 a few fathoms beneath every atoll1 and 
nevertheless  throughout the immense    
areas above-named1 with not one point of
 rock  projecting above the level of the
 sea2 for we may judge with some        
accuracy of mountains beneath the sea1  
by those on the land2 and where  can we 
find a single chain several hundred     
miles in length and of  considerable    
breadth1 much less several such chains1 
with their many  broad summits attaining
 the same height1 within from #abj to   
#ahj feet8  ,if the data be thought     
insufficient1 on which ,i have grounded 
my  belief1 respecting the depth at     
which the reef-building polypifers can  
exist1 and it be assumed that they can  
flourish at a depth of even one  hundred
 fathoms1 yet the weight of the above   
argument is but little  diminished1 for 
it is almost equally improbable1 that as
 many submarine  mountains1 as there are

 low islands in the several great and   
widely  separated areas above specified1
 should all rise within six hundred     
feet of the surface of the sea and not  
one above it1 as that they  should be of
 the same height within the smaller     
limit of one or two  hundred feet4 ,so  
highly improbable is this supposition1  
that we are  compelled to believe1 that 
the bases of the many atolls did never  
at  any one period all lie submerged    
within the depth of a few fathoms       
beneath the surface1 but that they were 
brought into the requisite  position or 
level1 some at one period and some at   
another1 through  movements in the      
earth's crust4 ,but this could not have 
been effected  by elevation1 for the    
belief that points so numerous and so   
widely  separated were successively     
uplifted to a certain level1 but that   
not  one point was raised above that    
level1 is quite as improbable as the    
former supposition1 and indeed differs  
little from it4 ,it will probably  occur

 to those who have read ,ehrenberg's    
account of the ,reefs of the  ,red ,sea1
 that many points in these great areas  
may have been elevated1  but that as    
soon as raised1 the protuberant parts   
were cut off by the  destroying action  
of the waves3 a moment's reflection1    
however1 on the  basin-like form of the 
atolls1 will show that this is          
impossible2 for  the upheaval and       
subsequent abrasion of an island would  
leave a flat  disc1 which might become  
coated with coral1 but not a deeply     
concave  surface2 moreover1 we should   
expect to see1 in some parts at least1  
the  rock of the foundation brought to  
the surface4 ,if1 then1 the  foundations
 of the many atolls were not uplifted   
into the requisite  position1 they must 
of necessity have subsided into it2 and 
this at  once solves every difficulty1#d
 for we may safely infer1 from the      
facts given in the last chapter1 that   
during a gradual subsidence the  corals 
would be favourably circumstanced for   

building up their solid  frame works and
 reaching the surface1 as island after  
island slowly  disappeared4 ,thus areas 
of immense extent in the central and    
most  profound parts of the great       
oceans1 might become interspersed with  
coral-islets1 none of which would rise  
to a greater height than that  attained 
by detritus heaped up by the sea1 and   
nevertheless they might  all have been  
formed by corals1 which absolutely      
required for their  growth a solid      
foundation within a few fathoms of the  
surface4     #d ,the additional         
difficulty on the crater hypothesis     
before alluded   to1 will now be        
evident2 for on this view the volcanic  
action must be   supposed to have formed
 within the areas specified a vast      
number of   craters1 all rising within a
 few fathoms of the surface1 and not one
   above it4 ,the supposition that the  
craters were at different times         
upraised above the surface1 and were    
there abraded by the surf and           

subsequently coated by corals1 is       
subject to nearly the same   objections 
with those given above in this          
paragraph2 but ,i consider it           
superfluous to detail all the arguments 
opposed to such a notion4   ,chamisso's 
theory1 from assuming the existence of  
so many banks1 all   lying at the proper
 depth beneath the water1 is also       
vitally   defective4 ,the same          
observation applies to an hypothesis of 
,lieutenant   ,nelson's 78,geolog4      
,trans40 volume v41 page #abb71 who     
supposes that the   ring-formed         
structure is caused by a greater number 
of germs of corals   becoming attached  
to the declivity1 than to the central   
plateau of a   submarine bank3 it       
likewise applies to the notion formerly 
entertained   7,forster's 8,observ40    
page #aea71 that lagoon-islands owe     
their peculiar   form to the instinctive
 tendencies of the polypifers4          
,according to   this latter view1 the   
corals on the outer margin of the reef  

instinctively expose themselves to the  
surf in order to afford   protection to 
corals living in the lagoon1 which      
belong to other   genera1 and to other  
families6      ,it would be out of place
 here to do more than allude to the many
 facts1  showing that the supposition of
 a gradual subsidence over large areas  
is by no means improbable4 ,we have the 
clearest proof that a movement  of this 
kind is possible1 in the upright trees  
buried under the strata  many thousand  
feet in thickness2 we have also every   
reason for  believing that there are now
 large areas gradually sinking1 in the  
same  manner as others are rising4 ,and 
when we consider how many parts of the  
surface of the globe have been elevated 
within recent geological  periods1 we   
must admit that there have been         
subsidences on a  corresponding scale1  
for otherwise the whole globe would have
 swollen4  ,it is very remarkable that  
,mr4 ,lyell1#e even in the first edition
 of  his 8,principles of ,geology10     

inferred that the amount of subsidence  
in  the ,pacific must have exceeded that
 of elevation1 from the area of land    
being very small relatively to the      
agents there tending to form it1        
namely1 the growth of coral and volcanic
 action4 ,but it will be asked1  are    
there any direct proofs of a subsiding  
movement in those areas1 in  which      
subsidence will explain a phenomenon    
otherwise inexplicable8  ,this1 however1
 can hardly be expected1 for it must    
ever be most  difficult1 excepting in   
countries long civilised1 to detect a   
movement1  the tendency of which is to  
conceal the part affected4 ,in barbarous
 and  semi-civilised nations how long   
might not a slow movement1 even of      
elevation such as that now affecting    
,scandinavia1 have escaped  attention6  
#e 8,principles of ,geology10 sixth     
edition1 volume iii41 page #chf4        
,mr4 ,williams#f insists strongly that  
the traditions of the natives1  which he
 has taken much pains in collecting1 do 

not indicate the  appearance of any new 
islands3 but on the theory of a gradual 
subsidence1 all that would be apparent  
would be1 the water sometimes           
encroaching slowly on the land1 and the 
land again recovering by the            
accumulation of detritus its former     
extent1 and perhaps sometimes the       
conversion of an atoll with coral islets
 on it1 into a bare or into a  sunken   
annular reef4 ,such changes would       
naturally take place at the  periods    
when the sea rose above its usual       
limits1 during a gale of more  than     
ordinary strength2 and the effects of   
the two causes would be  hardly         
distinguishable4 ,in ,kotzebue's        
8,voyage0 there are accounts of         
islands1 both in the ,caroline and      
,marshall ,archipelagoes1 which have    
been partly washed away during          
hurricanes2 and ,kadu1 the native who   
was  on board one of the ,russian       
vessels1 said 8he saw the sea at ,radack
  rise to the feet of the cocoa-nut     

trees2 but it was conjured in  time40#g 
,a storm lately entirely swept away two 
of the ,caroline  islands1 and converted
 them into shoals2 it partly1 also1     
destroyed two  other islands4#h         
,according to a tradition which was     
communicated to  ,captain ,fitzroy1 it  
is believed in the ,low ,archipelago1   
that the  arrival of the first ship     
caused a great inundation1 which        
destroyed  many lives4 ,mr4 ,stutchbury 
relates1 that in #ahbe1 the western side
 of  ,chain ,atoll1 in the same group1  
was completely devastated by a          
hurricane1 and not less than #cjj lives 
lost3 8in this instance it was  evident1
 even to the natives1 that the hurricane
 alone was not  sufficient to account   
for the violent agitation of the        
ocean40#i ,that  considerable changes   
have taken place recently in some of the
 atolls in  the ,low ,archipelago1      
appears certain from the case already   
given of  ,matilda ,island3 with respect
 to ,whitsunday and ,gloucester ,islands

 in  this same group1 we must either    
attribute great inaccuracy to their     
discoverer1 the famous circumnavigator  
,wallis1 or believe that they  have     
undergone a considerable change in the  
period of fifty-nine years1  between his
 voyage and that of ,captain ,beechey's4
 ,whitsunday ,island is  described by   
,wallis as 8about four miles long1 and  
three wide10 now it  is only one mile   
and a half long4 ,the appearance of     
,gloucester ,island1  in ,captain       
,beechey's words1#aj 8has been          
accurately described by its  discoverer1
 but its present form and extent differ 
materially40  ,blenheim reef1 in the    
,chagos group1 consists of a            
water-washed annular  reef1 thirteen    
miles in circumference1 surrounding a   
lagoon ten fathoms  deep3 on its surface
 there were a few worn patches of       
conglomerate  coral-rock1 of about the  
size of hovels2 and these ,captain      
,moresby  considered as being1 without  
doubt1 the last remnants of islets2 so  

that here an atoll has been converted   
into an atoll-formed reef4 ,the         
inhabitants of the ,maldiva             
,archipelago1 as long ago as #afje1     
declared1  8that the high tides and     
violent currents were diminishing the   
number  of the islands30#aa and ,i have 
already shown1 on the authority of      
,captain ,moresby1 that the work of     
destruction is still in progress2 but   
that on the other hand the first        
formation of some islets is known to    
the present inhabitants4 ,in such cases1
 it would be exceedingly  difficult to  
detect a gradual subsidence of the      
foundation1 on which  these mutable     
structures rest4     #f ,williams's     
8,narrative of ,missionary ,enterprise10
 page #ca4       #g ,kotzebue's 8,first 
,voyage10 volume iii41 page #afh4       
#h ,m4 ,desmoulins in 8,comptes         
,rendus10 #ahdj1 page #hcg4       #i    
8,west of ,england ,journal01 ,no4 ,i41 
page #ce4       #aj ,beechey's 8,voyage 
to the ,pacific10 chapter vii41 and     

,wallis's   8,voyage in the             
#8,dolphin'10 chapter iv4       #aa ,see
 an extract from ,pyrard's ,voyage in   
,captain ,owen's paper on   the ,maldiva
 ,archipelago1 in the 8,geographical    
,journal01 volume ii41   page #hd4      
,some of the archipelagoes of low       
coral-islands are subject to            
earthquakes3 ,captain ,moresby informs  
me that they are frequent1 though  not  
very strong1 in the ,chagos group1 which
 occupies a very central  position in   
the ,indian ,ocean1 and is far from any 
land not of coral  formation4 ,one of   
the islands in this group was formerly  
covered by a  bed of mould1 which1 after
 an earthquake1 disappeared1 and was    
believed  by the residents to have been 
washed by the rain through the broken   
masses of underlying rock2 the island   
was thus rendered unproductive4         
,chamisso#ab states1 that earthquakes   
are felt in the ,marshall atolls1  which
 are far from any high land1 and        
likewise in the islands of the          

,caroline ,archipelago4 ,on one of the  
latter1 namely ,oulleay atoll1  ,admiral
 ,lutk1 as he had the kindness to inform
 me1 observed several  straight fissures
 about a foot in width1 running for some
 hundred yards  obliquely across the    
whole width of the reef4 ,fissures      
indicate a  stretching of the earth's   
crust1 and1 therefore1 probably changes 
in  its level2 but these coral-islands1 
which have been shaken and  fissured1   
certainly have not been elevated1 and1  
therefore1 probably  they have subsided4
 ,in the chapter on ,keeling atoll1 ,i  
attempted to  show by direct evidence1  
that the island underwent a movement of 
subsidence1 during the earthquakes      
lately felt there4     #ab ,see         
,chamisso1 in ,kotzebue's 8,first       
,voyage10 volume iii41 pages   #ahb and 
#acf4      ,the facts stand thus2--there
 are many large tracts of ocean1 without
 any  high land1 interspersed with reefs
 and islets1 formed by the growth of    
those kinds of corals1 which cannot live

 at great depths2 and the  existence of 
these reefs and low islets1 in such     
numbers and at such  distant points1 is 
quite inexplicable1 excepting on the    
theory1 that  the bases on which the    
reefs first became attached1 slowly and 
successively sank beneath the level of  
the sea1 whilst the corals  continued to
 grow upwards4 ,no positive facts are   
opposed to this view1  and some general 
considerations render it probable4      
,there is evidence  of change in form1  
whether or not from subsidence1 on some 
of these  coral-islands2 and there is   
evidence of subterranean disturbances   
beneath them4 ,will then the theory1 to 
which we have thus been led1  solve the 
curious problem1--what has given to each
 class of reef its  peculiar form8      
,illustration    ,,aa--,outer edge of   
the reef at the level of the sea4       
,,bb--,shores of the island4            
,a,a--,outer edge of the reef1 after its
 upward growth during a period of       
subsidence4    ,,cc--,the lagoon-channel

 between the reef and the shores of the 
now  encircled land4    ,b,b--,the      
shores of the encircled island4         
,n4,b4--,in this1 and the following     
woodcut1 the subsidence of the land     
could only be represented by an apparent
 rise in the level of the sea4          
,illustration    ,a,a--,outer edges of  
the barrier-reef at the level of the    
sea4 ,the  cocoa-nut trees represent    
coral-islets formed on the reef4        
,,cc--,the lagoon-channel4    ,b,b--,the
 shores of the island1 generally formed 
of low alluvial land  and of coral      
detritus from the lagoon-channel4       
,a,a--,the outer edges of the reef now  
forming an atoll4    ,c--,the lagoon of 
the newly formed atoll4 ,according to   
the scale1 the  depth of the lagoon and 
of the lagoon-channel is exaggerated4   
,let us in imagination place within one 
of the subsiding areas1 an  island      
surrounded by a 8fringing-reef10--that  
kind1 which alone offers  no difficulty 
in the explanation of its origin4 ,let  

the unbroken lines  and the oblique     
shading in the woodcut 7,no4 #d7        
represent a vertical  section through   
such an island2 and the horizontal      
shading will  represent the section of  
the reef4 ,now1 as the island sinks     
down1  either a few feet at a time or   
quite insensibly1 we may safely infer   
from what we know of the conditions     
favourable to the growth of coral1  that
 the living masses bathed by the surf on
 the margin of the reef1  will soon     
regain the surface4 ,the water1 however1
 will encroach1 little  by little1 on   
the shore1 the island becoming lower and
 smaller1 and the  space between the    
edge of the reef and the beach          
proportionately  broader4 ,a section of 
the reef and island in this state1 after
 a  subsidence of several hundred feet1 
is given by the dotted lines3           
coral-islets are supposed to have been  
formed on the new reef1 and a  ship is  
anchored in the lagoon-channel4 ,this   
section is in every  respect that of an 

encircling barrier-reef2 it is1 in fact1
 a section  taken#ac ,e4 and ,w4 through
 the highest point of the encircled     
island  of ,bolabola2 of which a plan is
 given in ,plate ,i41 ,figure #e4 ,the  
same  section is more clearly shown in  
the following woodcut 7,no4 #e7 by the  
unbroken lines4 ,the width of the reef1 
and its slope1 both on the outer  and   
inner side1 will have been determined by
 the growing powers of the  coral1 under
 the conditions 7for instance the force 
of the breakers and  of the currents7 to
 which it has been exposed2 and the     
lagoon-channel  will be deeper or       
shallower1 in proportion to the growth  
of the  delicately branched corals      
within the reef1 and to the accumulation
 of  sediment1 relatively1 also1 to the 
rate of subsidence and the length of    
the intervening stationary periods4     
#ac ,the section has been made from the 
chart given in the 8,atlas of   the     
,voyage of the ,coquille40 ,the scale is
 4#eg of an inch to a mile4   ,the      

height of the island1 according to ,m4  
,lesson1 is #d1jbf feet4 ,the   deepest 
part of the lagoon-channel is #afb feet2
 its depth is   exaggerated in the      
woodcut for the sake of clearness4      
,it is evident in this section1 that a  
line drawn perpendicularly down  from   
the outer edge of the new reef to the   
foundation of solid rock1  exceeds by as
 many feet as there have been feet of   
subsidence1 that  small limit of depth  
at which the effective polypifers can   
live--the  corals having grown up1 as   
the whole sank down1 from a basis formed
 of  other corals and their consolidated
 fragments4 ,thus the difficulty on     
this head1 which before seemed so great1
 disappears4    ,as the space between   
the reef and the subsiding shore        
continued to  increase in breadth and   
depth1 and as the injurious effects of  
the  sediment and fresh water borne down
 from the land were consequently        
lessened1 the greater number of the     
channels1 with which the reef in  its   

fringing state must have been breached1 
especially those which  fronted the     
smaller streams1 will have become choked
 up with the growth  of coral3 on the   
windward side of the reef1 where the    
coral grows most  vigorously1 the       
breaches will probably have first been  
closed4 ,in  barrier-reefs1 therefore1  
the breaches kept open by draining the  
tidal  waters of the lagoon-channel1    
will generally be placed on the leeward 
side1 and they will still face the      
mouths of the larger streams1  although 
removed beyond the influence of their   
sediment and fresh  water2--and this1 it
 has been shown1 is commonly the case4  
,referring to the diagram shown above1  
in which the newly formed  barrier-reef 
is represented by unbroken lines1       
instead of by dots as in  the former    
woodcut1 let the work of subsidence go  
on1 and the doubly  pointed hill will   
form two small islands 7or more1        
according to the  number of the hills7  
included within one annular reef4 ,let  

the island  continue subsiding1 and the 
coral-reef will continue growing up on  
its  own foundation1 whilst the water   
gains inch by inch on the land1 until   
the last and highest pinnacle is        
covered1 and there remains a perfect    
atoll4 ,a vertical section of this atoll
 is shown in the woodcut by the  dotted 
lines2--a ship is anchored in its       
lagoon1 but islets are not  supposed yet
 to have been formed on the reef4 ,the  
depth of the lagoon  and the width and  
slope of the reef1 will depend on the   
circumstances  just referred to under   
barrier-reefs4 ,any further subsidence  
will  produce no change in the atoll1   
except perhaps a diminution in its      
size1 from the reef not growing         
vertically upwards2 but should the      
currents of the sea act violently upon  
it1 and should the corals perish  on    
part or on the whole of its margin1     
changes would result during  subsidence 
which will be presently noticed4 ,i may 
here observe1 that a  bank either of    

rock or of hardened sediment1 level with
 the surface of  the sea1 and fringed   
with living coral1 would 7if not so     
small as to  allow the central space to 
be quickly filled up with detritus7 by  
subsidence be converted immediately into
 an atoll1 without passing1 as  in the  
case of a reef fringing the shore of an 
island1 through the  intermediate form  
of a barrier-reef4 ,if such a bank lay a
 few fathoms  submerged1 the simple     
growth of the coral 7as remarked in the 
third  chapter7 without the aid of      
subsidence1 would produce a structure   
scarcely to be distinguished from a true
 atoll2 for in all cases the  corals on 
the outer margin of a reef1 from having 
space and being  freely exposed to the  
open sea1 will grow vigorously and tend 
to form a  continuous ring whilst the   
growth of the less massive kinds on the 
central expanse1 will be checked by the 
sediment formed there1 and by  that     
washed inwards by the breakers2 and as  
the space becomes  shallower1 their     

growth will1 also1 be checked by the    
impurities of the  water1 and probably  
by the small amount of food brought by  
the  enfeebled currents1 in proportion  
to the surface of living reefs  studded 
with innumerable craving mouths3 the    
subsidence of a reef based  on a bank of
 this kind1 would give depth to its     
central expanse or  lagoon1 steepness to
 its flanks1 and through the free growth
 of the  coral1 symmetry to its         
outline3--,i may here repeat that the   
larger  groups of atolls in the ,pacific
 and ,indian ,oceans cannot be supposed 
to  be founded on banks of this nature4 
,if1 instead of the island in the       
diagram1 the shore of a continent       
fringed by a reef had subsided1 a great 
barrier-reef1 like that on the          
north-east coast of ,australia1 would   
have necessarily resulted2 and it  would
 have been separated from the main land 
by a deep-water channel1  broad in      
proportion to the amount of subsidence1 
and to the less or  greater inclination 

of the neighbouring coast-line4 ,the    
effect of the  continued subsidence of a
 great barrier-reef of this kind1 and   
its  probable conversion into a chain of
 separate atolls1 will be noticed1  when
 we discuss the apparent progressive    
disseverment of the larger  ,maldiva    
atolls4    ,we now are able to perceive 
that the close similarity in form1      
dimensions1 structure1 and relative     
position 7which latter point will       
hereafter be more fully noticed7 between
 fringing and encircling  barrier-reefs1
 and between these latter and atolls1 is
 the necessary  result of the           
transformation1 during subsidence of the
 one class into  the other4 ,on this    
view1 the three classes of reefs ought  
to graduate  into each other4 ,reefs    
having intermediate character between   
those of  the fringing and barrier      
classes do exist2 for instance1 on the  
south-west coast of ,madagascar1 a reef 
extends for several miles1  within which
 there is a broad channel from seven to 

eight fathoms deep1  but the sea does   
not deepen abruptly outside the reef4   
,such cases1  however1 are open to some 
doubts1 for an old fringing-reef1 which 
had  extended itself a little on a basis
 of its own formation1 would hardly  be 
distinguishable from a barrier-reef1    
produced by a small amount of           
subsidence1 and with its lagoon-channel 
nearly filled up with sediment  during a
 long stationary period4 ,between       
barrier-reefs1 encircling  either one   
lofty island or several small low ones1 
and atolls including  a mere expanse of 
water1 a striking series can be shown3  
in proof of  this1 ,i need only refer to
 the first plate in this volume1 which  
speaks  more plainly to the eye1 than   
any description could to the ear4 ,the  
authorities from which the charts have  
been engraved1 together with  some      
remarks on them and descriptive of the  
plates1 are given above4 ,at  ,new      
,caledonia 7,plate ,,ii41 ,figure #e47  
the barrier-reefs extend for #aej  miles

 on each side of the submarine          
prolongation of the island2 and at      
their northern extremity they appear    
broken up and converted into a  vast    
atoll-formed reef1 supporting a few low 
coral-islets3 we may  imagine that we   
here see the effects of subsidence      
actually in  progress1 the water always 
encroaching on the northern end of the  
island1 towards which the mountains     
slope down1 and the reefs steadily      
building up their massive fabrics in the
 lines of their ancient growth4    ,we  
have as yet only considered the origin  
of barrier-reefs and atolls  in their   
simplest form2 but there remain some    
peculiarities in  structure and some    
special cases1 described in the two     
first chapters1  to be accounted for by 
our theory4 ,these consist--in the      
inclined ledge  terminated by a wall1   
and sometimes succeeded by a second     
ledge with a  wall1 round the shores of 
certain lagoons and lagoon-channels2 a  
structure which cannot1 as ,i           

endeavoured to show1 be explained by the
  simple growing powers of the          
corals1--in the ring or basin-like forms
 of  the central reefs1 as well as of   
the separate marginal portions of the   
northern ,maldiva atolls1--in the       
submerged condition of the whole1 or of 
parts of certain barrier and            
atoll-formed reefs2 where only a part is
  submerged1 this being generally to    
leeward1--in the apparent progressive   
disseverment of some of the ,maldiva    
atolls1--in the existence of            
irregularly formed atolls1 some being   
tied together by linear reefs1  and     
others with spurs projecting from       
them1--and1 lastly1 in the  structure   
and origin of the ,great ,chagos bank4  
,step-formed ledges round certain       
lagoons4--,if we suppose an atoll to    
subside at an extremely slow rate1 it is
 difficult to follow out the  complex   
results4 ,the living corals would grow  
up on the outer margin2  and likewise   
probably in the gullies and deeper parts

 of the bare  surface of the annular    
reef2 the water would encroach on the   
islets1  but the accumulation of fresh  
detritus might possibly prevent their   
entire submergence4 ,after a subsidence 
of this very slow nature1 the  surface  
of the annular reef sloping gently into 
the lagoon1 would  probably become      
united with the irregular reefs and     
banks of sand1  which line the shores of
 most lagoons4 ,should1 however1 the    
atoll be  carried down by a more rapid  
movement1 the whole surface of the      
annular  reef1 where there was a        
foundation of solid matter1 would be    
favourably  circumstanced for the fresh 
growth of coral2 but as the corals grew 
upwards on its exterior margin1 and the 
waves broke heavily on this  part1 the  
increase of the massive polypifers on   
the inner side would be  checked from   
the want of water4 ,consequently1 the   
exterior parts would  first reach the   
surface1 and the new annular reef thus  
formed on the  old one1 would have its  

summit inclined inwards1 and be         
terminated by a  subaqueous wall1 formed
 by the upward growth of the coral      
7before being  much checked71 from the  
inner edge of the solid parts of the old
 reef4  ,the inner portion of the new   
reef1 from not having grown to the      
surface1 would be covered by the waters 
of the lagoon4 ,should a  subsidence of 
the same kind be repeated1 the corals   
would again grow up  in a wall1 from all
 the solid parts of the resunken reef1  
and1  therefore1 not from within the    
sandy shores of the lagoon2 and the     
inner part of the new annular reef      
would1 from being as before checked  in 
its upward growth1 be of less height    
than the exterior parts1 and  therefore 
would not reach the surface of the      
lagoon4 ,in this case the  shores of the
 lagoon would be surrounded by two      
inclined ledges1 one  beneath the other1
 and both abruptly terminated by        
subaqueous  cliffs4#ad     #ad          
,according to ,mr4 ,couthouy 7page #bf7 

the external reef round many   atolls   
descends by a succession of ledges or   
terraces4 ,he attempts1 ,i   doubt      
whether successfully1 to explain this   
structure somewhat in the   same manner 
as ,i have attempted1 with respect to   
the internal ledges   round the lagoons 
of some atolls4 ,more facts are wanted  
regarding the   nature both of the      
interior and exterior step-like ledges3 
are all the   ledges1 or only the upper 
ones1 covered with living coral8 ,if    
they are   all covered1 are the kinds   
different on the ledges according to the
   depth8 ,do the interior and exterior 
ledges occur together in the same       
atolls2 if so1 what is their total      
width1 and is the intervening           
surface-reef narrow1 etc48      ,the    
ring or basin-formed reefs of the       
northern ,maldiva atolls4--,i may  first
 observe1 that the reefs within the     
lagoons of atolls and within            
lagoon-channels1 would1 if favourably   
circumstanced1 grow upwards  during     

subsidence in the same manner as the    
annular rim2 and1  therefore1 we might  
expect that such lagoon-reefs1 when not 
surrounded  and buried by an            
accumulation of sediment more rapid than
 the rate of  subsidence1 would rise    
abruptly from a greater depth than that 
at which  the efficient polypifers can  
flourish3 we see this well exemplified  
in  the small abruptly-sided reefs1 with
 which the deep lagoons of the  ,chagos 
and ,southern ,maldiva atolls are       
studded4 ,with respect to the  ring or  
basin-formed reefs of the ,northern     
,maldiva atolls1 it is  evident1 from   
the perfectly continuous series which   
exists that the  marginal rings1        
although wider than the exterior or     
bounding reef of  ordinary atolls1 are  
only modified portions of such a reef2  
it is also  evident that the central    
rings1 although wider than the knolls or
 reefs  which commonly occur in lagoons1
 occupy their place4 ,the ring-like     
structure has been shown to be          

contingent on the breaches into the     
lagoon being broad and numerous1 so that
 all the reefs which are bathed  by the 
waters of the lagoon are placed under   
nearly the same conditions  with the    
outer coast of an atoll standing in the 
open sea4 ,hence the  exterior and      
living margins of these reefs must have 
been favourably  circumstanced for      
growing outwards1 and increasing beyond 
the usual  breadth2 and they must       
likewise have been favourably           
circumstanced for  growing vigorously   
upwards1 during the subsiding movements1
 to which by  our theory the whole      
archipelago has been subjected2 and     
subsidence  with this upward growth of  
the margins would convert the central   
space  of each little reef into a small 
lagoon4 ,this1 however1 could only take 
place with those reefs1 which had       
increased to a breadth sufficient to    
prevent their central spaces from being 
almost immediately filled up  with the  
sand and detritus driven inwards from   

all sides3 hence it is  that few reefs1 
which are less than half a mile in      
diameter1 even in  the atolls where the 
basin-like structure is most strikingly 
exhibited1  include lagoons4 ,this      
remark1 ,i may add1 applies to all      
coral-reefs  wherever found4 ,the       
basin-formed reefs of the ,maldiva      
,archipelago may1  in fact1 be briefly  
described1 as small atolls formed during
 subsidence  over the separate portions 
of large and broken atolls1 in the same 
manner as these latter were formed over 
the barrier-reefs1 which  encircled the 
islands of a large archipelago now      
wholly submerged4    ,submerged and     
,dead ,reefs4--,in the second section of
 the first chapter1  ,i have shown that 
there are in the neighbourhood of       
atolls1 some deeply  submerged banks1   
with level surfaces2 that there are     
others1 less  deeply but yet wholly     
submerged1 having all the characters of 
perfect  atolls1 but consisting merely  
of dead coral-rock2 that there are      

barrier-reefs and atolls with merely a  
portion of their reef1 generally  on the
 leeward side1 submerged2 and that such 
portions either retain  their perfect   
outline1 or they appear to be quite     
effaced1 their former  place being      
marked only by a bank1 conforming in    
outline with that part  of the reef     
which remains perfect4 ,these several   
cases are1 ,i believe1  intimately      
related together1 and can be explained  
by the same means4  ,there1 perhaps1    
exist some submerged reefs1 covered with
 living coral  and growing upwards1 but 
to these ,i do not here refer4    ,as we
 see that in those parts of the ocean1  
where coral-reefs are most  abundant1   
one island is fringed and another       
neighbouring one is not  fringed2 as we 
see in the same archipelago1 that all   
the reefs are more  perfect in one part 
of it than in another1 for instance1 in 
the  southern half compared with the    
northern half of the ,maldiva           
,archipelago1 and likewise on the outer 

coasts compared with the inner  coasts  
of the atolls in this same group1 which 
are placed in a double  row2 as we know 
that the existence of the innumerable   
polypifers  forming a reef1 depends on  
their sustenance1 and that they are     
preyed  on by other organic beings2 and1
 lastly1 as we know that some inorganic 
causes are highly injurious to the      
growth of coral1 it cannot be  expected 
that during the round of change to which
 earth1 air1 and water  are exposed1 the
 reef-building polypifers should keep   
alive for  perpetuity in any one place2 
and still less can this be expected1    
during the progressive subsidences1     
perhaps at some periods more rapid  than
 at others1 to which by our theory these
 reefs and islands have  been subjected 
and are liable4 ,it is1 then1 not       
improbable that the  corals should      
sometimes perish either on the whole or 
on part of a  reef2 if on part1 the dead
 portion1 after a small amount of       
subsidence1  would still retain its     

proper outline and position beneath the 
water4  ,after a more prolonged         
subsidence1 it would probably form1     
owing to the  accumulation of sediment1 
only the margin of a flat bank1 marking 
the  limits of the former lagoon4 ,such 
dead portions of reef would generally   
lie on the leeward side1#ae for the     
impure water and fine sediment  would   
more easily flow out from the lagoon    
over this side of the reef1  where the  
force of the breakers is less than to   
windward2 and therefore  the corals     
would be less vigorous on this side1 and
 be less able to  resist any destroying 
agent4 ,it is likewise owing to this    
same cause1  that reefs are more        
frequently breached to leeward by narrow
 channels1  serving as by ship-channels1
 than to windward4 ,if the corals       
perished  entirely1 or on the greater   
part of the circumference of an atoll1  
an  atoll-shaped bank of dead rock1 more
 or less entirely submerged1 would  be  
produced2 and further subsidence1       

together with the accumulation of       
sediment1 would often obliterate its    
atoll-like structure1 and leave  only a 
bank with a level surface4     #ae ,mr4 
,lyell1 in the first edition of his     
8,principles of ,geology10   offered a  
somewhat different explanation of this  
structure4 ,he   supposes that there has
 been subsidence2 but he was not aware  
that the   submerged portions of reef   
were in most cases1 if not in all1 dead2
   and he attributes the difference in  
height in the two sides of most         
atolls1 chiefly to the greater          
accumulation of detritus to windward    
than to leeward4 ,but as matter is      
accumulated only on the backward   part 
of the reef1 the front part would remain
 of the same height on   both sides4 ,i 
may here observe that in most cases 7for
 instance1 at   ,peros ,banhos1 the     
,gambier group and the ,great ,chagos   
,bank71 and ,i   suspect in all cases1  
the dead and submerged portions do not  
blend or   slope into the living and    

perfect parts1 but are separated from   
them   by an abrupt line4 ,in some      
instances small patches of living reef  
rise   to the surface from the middle of
 the submerged and dead parts4      ,in 
the ,chagos group of atolls1 within an  
area of #afj miles by #fj1 there  are   
two atoll-formed banks of dead rock     
7besides another very imperfect  one71  
entirely submerged2 a third1 with merely
 two or three very small  pieces of     
living reef rising to the surface2 and a
 fourth1 namely1  ,peros ,banhos 7,plate
 ,i41 ,figure #i71 with a portion nine  
miles in length  dead and submerged4 ,as
 by our theory this area has subsided1  
and as  there is nothing improbable in  
the death1 either from changes in the   
state of the surrounding sea or from the
 subsidence being great or  sudden1 of  
the corals on the whole1 or on portions 
of some of the  atolls1 the case of the 
,chagos group presents no difficulty4   
,so far  indeed are any of the          
above-mentioned cases of submerged reefs

 from  being inexplicable1 that their   
occurrence might have been anticipated  
on our theory1 and as fresh atolls are  
supposed to be in progressive  formation
 by the subsidence of encircling        
barrier-reefs1 a weighty  objection1    
namely that the number of atolls must be
 increasing  infinitely1 might even have
 been raised1 if proofs of the          
occasional  destruction and loss of     
atolls could not have been adduced4     
,the disseverment of the larger ,maldiva
 atolls4--,the apparent  progressive    
disseverment in the ,maldiva            
,archipelago of large atolls  into      
smaller ones1 is1 in many respects1 an  
important consideration1  and requires  
an explanation4 ,the graduated series   
which marks1 as ,i  believe1 this       
process1 can be observed only in the    
northern half of the  group1 where the  
atolls have exceedingly imperfect       
margins1 consisting  of detached        
basin-formed reefs4 ,the currents of the
 sea flow across  these atolls1 as ,i am

 informed by ,captain ,moresby1 with    
considerable  force1 and drift the      
sediment from side to side during the   
monsoons1  transporting much of it      
seaward2 yet the currents sweep with    
greater  force round their flanks4 ,it  
is historically known that these atolls 
have long existed in their present      
state2 and we can believe1 that even    
during a very slow subsidence they might
 thus remain1 the central  expanse being
 kept at nearly its original depth by   
the accumulation of  sediment4 ,but in  
the action of such nicely balanced      
forces during a  progressive subsidence 
7like that1 to which by our theory this 
archipelago has been subjected71 it     
would be strange if the currents of  the
 sea should never make a direct passage 
across some one of the  atolls1 through 
the many wide breaches in their margins4
 ,if this were  once effected1 a        
deep-water channel would soon be formed 
by the removal  of the finer sediment1  
and the check to its further            

accumulation2 and  the sides of the     
channel would be worn into a slope like 
that on the  outer coasts1 which are    
exposed to the same force of the        
currents4 ,in  fact1 a channel precisely
 like that bifurcating one which divides
  ,mahlos ,mahdoo 7,plate ,,ii41 ,figure
 #d471 would almost necessarily be      
formed4 ,the scattered reefs situated   
near the borders of the new             
ocean-channel1 from being favourably    
placed for the growth of coral1  would1 
by their extension1 tend to produce     
fresh margins to the  dissevered        
portions2 such a tendency is very       
evident 7as may be seen in  the large   
published chart7 in the elongated reefs 
on the borders of the  two channels     
intersecting ,mahlos ,mahdoo4 ,such     
channels would become  deeper with      
continued subsidence1 and probably from 
the reefs not  growing up               
perpendicularly1 somewhat broader4 ,in  
this case1 and more  especially if the  
channels had been formed originally of  

considerable  breadth1 the dissevered   
portions would become perfect and       
distinct  atolls1 like ,ari and ,ross   
atolls 7,plate ,,ii41 ,figure #f71 or   
like the two  ,nillandoo atolls1 which  
must be considered as distinct1 although
  related in form and position1 and     
separated from each other by  channels1 
which though deep have been sounded4    
,further subsidence would  render such  
channels unfathomable1 and the          
dissevered portions would  then resemble
 ,phaleedoo and ,moluque atolls1 or     
,mahlos ,mahdoo and  ,horsburgh atolls  
7,plate ,,ii41 ,figure #d71 which are   
related to each other  in no respect    
except in proximity and position4       
,hence1 on the theory of  subsidence1   
the disseverment of large atolls1 which 
have imperfect  margins 7for otherwise  
their disseverment would be scarcely    
possible71  and which are exposed to    
strong currents1 is far from being an   
improbable event2 and the several       
stages1 from close relation to entire   

isolation in the atolls of the ,maldiva 
,archipelago1 are readily  explicable4  
,we might go even further1 and assert as
 not improbable1 that the first         
formation of the ,maldiva ,archipelago  
was due to a barrier-reef1 of  nearly   
the same dimensions with that of ,new   
,caledonia 7,plate ,,ii41  ,figure #e71 
for if1 in imagination1 we complete the 
subsidence of that  great island1 we    
might anticipate from the present broken
 condition of  the northern portion of  
the reef1 and from the almost entire    
absence of  reefs on the eastern coast1 
that the barrier-reef after repeated    
subsidences1 would become during its    
upward growth separated into  distinct  
portions2 and these portions would tend 
to assume an  atoll-like structure1 from
 the coral growing with vigour round    
their  entire circumferences1 when      
freely exposed to an open sea4 ,as we   
have  some large islands partly         
submerged with barrier-reefs marking    
their  former limits1 such as ,new      

,caledonia1 so our theory makes it      
probable  that there should be other    
large islands wholly submerged2 and     
these1  we may now infer1 would be      
surmounted1 not by one enormous atoll1  
but  by several large elongated ones1   
like the atolls in the ,maldiva group2  
and these again1 during long periods of 
subsidence1 would sometimes  become     
dissevered into smaller atolls4 ,i may  
add1 that both in the  ,marshall and    
,caroline ,archipelagoes1 there are     
atolls standing close  together1 which  
have an evident relationship in form3 we
 may suppose1  in such cases1 either    
that two or more encircled islands      
originally  stood close together1 and   
afforded bases for two or more atolls1  
or  that one atoll has been dissevered4 
,from the position1 as well as form1  of
 three atolls in the ,caroline          
,archipelago 7the ,namourrek and ,elato 
group71 which are placed in an irregular
 circle1 ,i am strongly tempted  to     
believe that they have originated by the

 process of  disseverment4#af     #af   
,the same remark is1 perhaps1 applicable
 to the islands of ,ollap1   ,fanadik1  
and ,tamatam in the ,caroline           
,archipelago1 of which charts are       
given in the atlas of ,duperrey's       
voyage3 a line drawn through the        
linear reefs and lagoons of these three 
islands forms a semicircle4   ,consult  
also1 the atlas of ,lutk's voyage2 and  
for the ,marshall group   that of       
,kotzebue2 for the ,gilbert group       
consult the atlas of   ,duperrey's      
voyage4 ,most of the points here        
referred to may1 however1   be seen in  
,krusenstern's general ,atlas of the    
,pacific4      ,irregularly formed      
,atolls4--,in the ,marshall group1      
,musquillo atoll  consists of two loops 
united in one point2 and ,menchikoff    
atoll is  formed of three loops1 two of 
which 7as may be seen in ,figure #c1    
,plate  ,,ii47 are connected by a mere  
ribbon-shaped reef1 and the three       
together  are sixty miles in length4 ,in

 the ,gilbert group some of the atolls  
have  narrow strips of reef1 like spurs1
 projecting from them4 ,there occur     
also in parts of the open sea1 a few    
linear and straight reefs1  standing by 
themselves2 and likewise some few reefs 
in the form of  crescents1 with their   
extremities more or less curled inwards4
 ,now1 the  upward growth of a          
barrier-reef which fronted only one side
 of an  island1 or one side of an       
elongated island with its extremities   
7of  which cases exist71 would produce  
after the complete subsidence of the    
land1 mere strips or crescent or        
hook-formed reefs3 if the island thus   
partially fronted became divided during 
subsidence into two or more  islands1   
these islands would be united together  
by linear reefs2 and  from the further  
growth of the coral along their shores  
together with  subsidence1 reefs of     
various forms might ultimately be       
produced1 either  atolls united together
 by linear reefs1 or atolls with spurs  

projecting  from them4 ,some1 however1  
of the more simple forms above          
specified1  might1 as we have seen1 be  
equally well produced by the coral      
perishing  during subsidence on part of 
the circumference of an atoll1 whilst on
  the other parts it continued to grow  
up till it reached the surface4    ,the 
,great ,chagos ,bank4--,i have already  
shown that the submerged  condition of  
the ,great ,chagos ,bank 7,plate ,,ii41 
,figure #a1 with its  section ,figure   
#b71 and of some other banks in the     
,chagos group1 may in  all probability  
be attributed to the coral having       
perished before or  during the movements
 of subsidence1 to which this whole area
 by our  theory has been subjected4 ,the
 external rim or upper ledge 7shaded in 
the chart71 consists of dead coral-rock 
thinly covered with sand2 it  lies at an
 average depth of between five and eight
 fathoms1 and  perfectly resembles in   
form the annular reef of an atoll4 ,the 
banks of  the second level1 the         

boundaries of which are marked by dotted
 lines in  the chart1 lie from about    
fifteen to twenty fathoms beneath the   
surface2 they are several miles broad1  
and terminate in a very steep  slope    
round the central expanse4 ,this central
 expanse ,i have already  described1 as 
consisting of a level muddy flat between
 thirty and forty  fathoms deep4 ,the   
banks of the second level1 might at     
first sight be  thought analogous to the
 internal step-like ledge of coral-rock 
which  borders the lagoons of some      
atolls1 but their much greater width1   
and  their being formed of sand1 are    
points of essential difference4 ,on the 
eastern side of the atoll some of the   
banks are linear and parallel1          
resembling islets in a great river1 and 
pointed directly towards a  great breach
 on the opposite side of the atoll2     
these are best seen in  the large       
published chart4 ,i inferred from this  
circumstance1 that  strong currents     
sometimes set directly across this vast 

bank2 and ,i  have since heard from     
,captain ,moresby that this is the case4
 ,i  observed1 also1 that the channels  
or breaches through the rim1 were all   
of the same depth as the central        
lagoon-like space into which they  lead2
 whereas the channels into the other    
atolls of the ,chagos group1  and as ,i 
believe into most other large atolls1   
are not nearly as deep  as their        
lagoons3 for instance at ,peros ,banhos1
 the channels are only  of the same     
depth1 namely between ten and twenty    
fathoms1 as the bottom  of the lagoon   
for a space about a mile and a half in  
width round its  shores1 whilst the     
central expanse of the lagoon is from   
thirty-five to  forty fathoms deep4     
,now1 if an atoll during a gradual      
subsidence once  became entirely        
submerged1 like the ,great ,chagos      
,bank1 and therefore no  longer exposed 
to the surf1 very little sediment could 
be formed from  it2 and consequently the
 channels leading into the lagoon from  

not  being filled up with drifted sand  
and coral detritus1 would continue      
increasing in depth1 as the whole sank  
down4 ,in this case1 we might  expect   
that the currents of the open sea1      
instead of any longer  sweeping round   
the submarine flanks1 would flow        
directly through the  breaches across   
the lagoon1 removing in their course the
 finer  sediment1 and preventing its    
further accumulation4 ,we should then   
have  the submerged reef forming an     
external and upper rim of rock1 and     
beneath this portion of the sandy bottom
 of the old lagoon1 intersected  by     
deep-water channels or breaches1 and    
thus formed into separate  marginal     
banks2 and these would be cut off by    
steep slopes1 overhanging  the central  
space1 worn down by the passage of the  
oceanic currents4    ,by these means1 ,i
 have scarcely any doubt that the ,great
 ,chagos ,bank  has originated1--a      
structure which at first appeared to me 
far more  anomalous than any ,i had met 

with4 ,the process of formation is      
nearly  the same with that1 by which    
,mahlos ,mahdoo had been trisected2 but 
in  the ,chagos ,bank the channels of   
the oceanic currents entering at        
several different quarters1 have united 
in a central space4    ,this great      
atoll-formed bank appears to be in an   
early stage of  disseverment2 should the
 work of subsidence go on1 from the     
submerged  and dead condition of the    
whole reef1 and the imperfection of the 
south-east quarter a mere wreck would   
probably be left4 ,the ,pitt's  ,bank1  
situated not far southward1 appears to  
be precisely in this  state2 it consists
 of a moderately level1 oblong bank of  
sand1 lying  from #aj to #bj fathoms    
beneath the surface1 with two sides     
protected by  a narrow ledge of rock    
which is submerged between #e and #h    
fathoms4 ,a  little further south1 at   
about the same distance as the southern 
rim of  the ,great ,chagos ,bank is from
 the northern rim1 there are two other  

small banks with from #aj to #bj fathoms
 on them2 and not far eastward          
soundings were struck on a sandy bottom1
 with between #aaj and #ade  fathoms4   
,the northern portion with its          
ledge-like margin1 closely  resembles   
any one segment of the ,great ,chagos   
,bank1 between two of the  deep-water   
channels1 and the scattered banks1      
southward appear to be  the last wrecks 
of less perfect portions4    ,i have    
examined with care the charts of the    
,indian and ,pacific ,oceans1  and have 
now brought before the reader all the   
examples1 which ,i have  met with1 of   
reefs differing from the type of the    
class to which they  belong2 and ,i     
think it has been satisfactorily shown1 
that they are all  included in our      
theory1 modified by occasional accidents
 which might  have been anticipated as  
probable4 ,in this course we have seen1 
that in  the lapse of ages encircling   
barrier-reefs are occasionally converted
  into atolls1 the name of atoll being  

properly applicable1 at the moment  when
 the last pinnacle of encircled land    
sinks beneath the surface of  the sea4  
,we have1 also1 seen that large atolls  
during the progressive  subsidence of   
the areas in which they stand1 sometimes
 become  dissevered into smaller ones2  
at other times1 the reef-building       
polypifers having entirely perished1    
atolls are converted into  atoll-formed 
banks of dead rock2 and these again     
through further  subsidence and the     
accumulation of sediment modified by the
 force of  the oceanic currents1 pass   
into level banks with scarcely any      
distinguishing character4 ,thus may the 
history of an atoll be followed  from   
its first origin1 through the occasional
 accidents of its  existence1 to its    
destruction and final obliteration4     
,objections to the theory of the        
formation of ,atolls and                
,barrier-reefs4--,the vast amount of    
subsidence1 both horizontally or in     
area1 and vertically or in depth1       

necessary to have submerged every       
mountain1 even the highest1 throughout  
the immense spaces of ocean             
interspersed with atolls1 will probably 
strike most people as a  formidable     
objection to my theory4 ,but as         
continents1 as large as the  spaces     
supposed to have subsided1 have been    
raised above the level of  the sea1--as 
whole regions are now rising1 for       
instance1 in ,scandinavia  and ,south   
,america1--and as no reason can be      
assigned1 why subsidences  should not   
have occurred in some parts of the      
earth's crust on as great  a scale both 
in extent and amount as those of        
elevation1 objections of  this nature   
strike me as of little force4 ,the      
remarkable point is that  movements to  
such an extent should have taken place  
within a period1  during which the      
polypifers have continued adding matter 
on and above  the same reefs4 ,another  
and less obvious objection to the theory
 will  perhaps be advanced from the     

circumstance1 of the lagoons within     
atolls  and within barrier-reefs never  
having become in any one instance during
  prolonged subsidences of a greater    
depth than sixty fathoms1 and seldom    
more than forty fathoms2 but we already 
admit1 if the theory be worth           
considering1 that the rate of subsidence
 has not exceeded that of the  upward   
growth of the coral on the exterior     
margin2 we are1 therefore1  only further
 required to admit1 that the subsidence 
has not exceeded in  rate the filling up
 of the interior spaces by the growth of
 the corals  living there1 and by the   
accumulation of sediment4 ,as this      
filling up  must take place very slowly 
within barrier-reefs lying far from the 
land1 and within atolls which are of    
large dimensions and which have  open   
lagoons with very few reefs1 we are led 
to conclude that the  subsidence thus   
counter-balanced1 must have been slow in
 an  extraordinary degree2 a conclusion 
which accords with our only means1      

namely1 with what is known of the rate  
and manner of recent elevatory          
movements1 of judging by analogy what is
 the probable rate of  subsidence4      
,in this chapter it has1 ,i think1 been 
shown1 that the theory of  subsidence1  
which we were compelled to receive from 
the necessity of  giving to the corals1 
in certain large areas1 foundations at  
the  requisite depth1 explains both the 
normal structure and the less  regular  
forms of those two great classes of     
reefs1 which have justly  excited the   
astonishment of all persons who have    
sailed through the  ,pacific and ,indian
 ,oceans4 ,but further to test the truth
 of the theory1  a crowd of questions   
will occur to the reader3 ,do the       
different kinds  of reefs1 which have   
been produced by the same kind of       
movement1  generally lie within the same
 areas8 ,what is their relation of form 
and  position1--for instance1 do        
adjoining groups of atolls1 and the     
separate  atolls in these groups1 bear  

the same relation to each other which   
islands do in common archipelagoes8     
,have we reason to believe1 that  where 
there are fringing-reefs1 there has not 
lately been subsidence2  or1 for it is  
almost our only way of ascertaining this
 point1 are there  frequently proofs of 
recent elevation8 ,can we by this means 
account for  the presence of certain    
classes of reefs in some large areas1   
and their  entire absence in others8 ,do
 the areas which have subsided1 as      
indicated by the presence of atolls and 
barrier-reefs1 and the areas  which have
 remained stationary or have been       
upraised1 as shown by  fringing-reefs1  
bear any determinate relation to each   
other2 and are  the dimensions of these 
areas such as harmonise with the        
greatness of  the subterranean changes1 
which1 it must be supposed1 have lately 
taken  place beneath them8 ,is there any
 connection between the movements thus  
indicated1 and recent volcanic action8  
,all these questions ought to  receive  

answers in accordance with the theory2  
and if this can be  satisfactorily      
shown1 not only is the theory confirmed1
 but as  deductions1 the answers are in 
themselves important4 ,under this latter
  point of view1 these questions will be
 chiefly considered in the  following   
chapter4#ag     #ag ,i may take this    
opportunity of briefly considering the  
appearances1 which would probably be    
presented by a vertical and deep        
section across a coral formation        
7referring chiefly to an atoll71        
formed by the upward growth of coral    
during successive subsidences4   ,this  
is a subject worthy of attention1 as a  
means of comparison with   ancient      
coral-strata4 ,the circumferential parts
 would consist of   massive species1 in 
a vertical position1 with their         
interstices filled   up with detritus2  
but this would be the part most subject 
to   subsequent denudation and removal4 
,it is useless to speculate how   large 
a portion of the exterior annular reef  

would consist of upright   coral1 and   
how much of fragmentary rock1 for this  
would depend on many                    
contingencies1--such as on the rate of  
subsidence1 occasionally   allowing a   
fresh growth of coral to cover the whole
 surface1 and on   the breakers having  
force sufficient to throw fragments over
 this same   space4 ,the conglomerate   
which composes the base of the islets1  
would   7if not removed by denudation   
together with the exterior reef on which
   it rests7 be conspicuous from the    
size of the fragments1--the different   
degrees in which they have been         
rounded1--the presence of fragments of  
conglomerate torn up1 rounded1 and      
recemented1--and from the oblique       
stratification4 ,the corals which lived 
in the lagoon-reefs at each   successive
 level1 would be preserved upright1 and 
they would consist   of many kinds1     
generally much branched4 ,in this part1 
however1 a very   large proportion of   
the rock 7and in some cases nearly all  

of it7   would be formed of sedimentary 
matter1 either in an excessively fine1  
or in a moderately coarse state1 and    
with the particles almost blended       
together4 ,the conglomerate which was   
formed of rounded pieces of the         
branched corals1 on the shores of the   
lagoon1 would differ from that   formed 
on the islets and derived from the outer
 coast2 yet both might   have           
accumulated very near each other4 ,i    
have seen a conglomerate   limestone    
from ,devonshire like a conglomerate now
 forming on the   shores of the ,maldiva
 atolls4 ,the stratification taken as a 
whole1   would be horizontal2 but the   
conglomerate beds resting on the        
exterior   reef1 and the beds of        
sandstone on the shores of the lagoon   
7and no   doubt on the external flanks7 
would probably be divided 7as at        
,keeling   atoll and at ,mauritius7 by  
numerous layers dipping at considerable 
angles in different directions4 ,the    
calcareous sandstone and   coral-rock   

would almost necessarily contain        
innumerable shells1   echini1 and the   
bones of fish1 turtle1 and perhaps of   
birds2 possibly1   also1 the bones of   
small saurians1 as these animals find   
their way to   the islands far remote   
from any continent4 ,the large shells of
 some   species of ,tridacna would be   
found vertically imbedded in the solid  
rock1 in the position in which they     
lived4 ,we might expect also to   find a
 mixture of the remains of pelagic and  
littoral animals in the   strata formed 
in the lagoon1 for pumice and the seeds 
of plants are   floated from distant    
countries into the lagoons of many      
atolls3 on the   outer coast of ,keeling
 atoll1 near the mouth of the lagoon1   
the case   of a pelagic ,pteropodous    
animal was brought up on the arming of  
the   sounding lead4 ,all the loose     
blocks of coral on ,keeling atoll were  
burrowed by vermiform animals2 and as   
every cavity1 no doubt1   ultimately    
becomes filled with spathose limestone1 

slabs of the rock   taken from a        
considerable depth1 would1 if polished1 
probably exhibit   the excavations of   
such burrowing animals4 ,the            
conglomerate and   fine-grained beds of 
coral-rock would be hard1 sonorous1     
white and   composed of nearly pure     
calcareous matter2 in some few parts1   
judging   from the specimens at ,keeling
 atoll1 they would probably contain a   
small quantity of iron4 ,floating pumice
 and scoriae1 and occasionally   stones 
transported in the root of trees 7see my
 8,journal of   ,researches10 page #edi7
 appear the only sources1 through which 
foreign   matter is brought to          
coral-formations standing in the open   
ocean4 ,the   area over which sediment  
is transported from coral-reefs must be 
considerable3 ,captain ,moresby informs 
me that during the change of   monsoons 
the sea is discoloured to a considerable
 distance off the   ,maldiva and ,chagos
 atolls4 ,the sediment of fringing and  
barrier   coral-reefs must be mingled   

with the mud1 which is brought down from
   the land1 and is transported seaward 
through the breaches1 which occur   in  
front of almost every valley4 ,if the   
atolls of the larger   archipelagoes    
were upraised1 the bed of the ocean     
being converted into   land1 they would 
form flat-topped mountains1 varying in  
diameter from   a few miles 7the        
smallest atolls being worn away7 to     
sixty miles2 and   from being           
horizontally stratified and of similar  
composition1 they   would1 as ,mr4      
,lyell has remarked1 falsely appear as  
if they had   originally been united    
into one vast continuous mass4 ,such    
great   strata of coral-rock would      
rarely be associated with erupted       
volcanic   matter1 for this could only  
take place1 as may be inferred from what
   follows in the next chapter1 when the
 area1 in which they were   situated1   
commenced to rise1 or at least ceased to
 subside4 ,during the   enormous period 
necessary to effect an elevation of the 

kind just   alluded to1 the surface     
would necessarily be denuded to a great 
thickness2 hence it is highly improbable
 that any fringing-reef1 or   even any  
barrier-reef1 at least of those         
encircling small islands1   would be    
preserved4 ,from this same cause1 the   
strata which were formed   within the   
lagoons of atolls and lagoon-channels of
 barrier-reefs1 and   which must consist
 in a large part of sedimentary matter1 
would more   often be preserved to      
future ages1 than the exterior solid    
reef1   composed of massive corals in an
 upright position2 although it is on    
this exterior part that the present     
existence and further growth of   atolls
 and barrier-reefs entirely depend4     
,,chapter ,,vi4    ,,on ,,the           
,,distribution ,,of ,,coral-,,reefs     
,,with ,,reference ,,to ,,the ,,theory  
,,of  ,,their ,,formation4              
,description of the coloured            
map4--,proximity of atolls and          
barrier-reefs4-- ,relation in form and  

position of atolls with ordinary        
islands4--,direct evidence of subsidence
 difficult to be detected4--,proofs  of 
recent elevation where fringing-reefs   
occur4--,oscillations of                
level4--,absence of active volcanoes in 
the areas of  subsidence4--,immensity of
 the areas which have been elevated and 
have  subsided4--,their relation to the 
present distribution of the             
land4--,areas  of subsidence elongated1 
their intersection and alternation with 
those  of elevation4--,amount and slow  
rate of the                             
subsidence4--,recapitulation4      ,it  
will be convenient to give here a short 
account of the appended map  7,plate    
,,iii47 ,inasmuch as the coloured map   
would have proved too costly  to be     
given in this series1 the indications of
 colour have been  replaced by numbers  
referring to the dotted groups of reefs1
 etc4 ,the  author's original wording1  
however1 is retained in full1 as it will
 be  easy to refer to the map by the    

numbers1 and thus the flow of the       
narrative is undisturbed43 a fuller one1
 with the data for colouring  each spot1
 is reserved for the ,appendix2 and     
every place there referred  to may be   
found in the ,index4 ,a larger chart    
would have been desirable2  but1 small  
as the adjoined one is1 it is the result
 of many months'  labour4 ,i have       
consulted1 as far as ,i was able1 every 
original voyage  and map2 and the       
colours were first laid down on charts  
on a larger  scale4 ,the same blue      
colour1 with merely a difference in the 
depth of  tint1 is used for atolls or   
lagoon-islands1 and barrier-reefs1 for  
we  have seen1 that as far as the actual
 coral-formation is concerned1 they     
have no distinguishing character4       
,fringing-reefs have been coloured  red1
 for between them on the one hand1 and  
barrier-reefs and atolls on  the other1 
there is an important distinction with  
respect to the depth  beneath the       
surface1 at which we are compelled to   

believe their  foundations lie4 ,the two
 distinct colours1 therefore1 mark two  
great  types of structure4    ,the dark 
blue colour represented by 7#c7 in our  
plate represents  atolls and submerged  
annular reefs1 with deep water in their 
centres4 ,i  have coloured as atolls1 a 
few low and small coral-islands1 without
  lagoons2 but this has been done only  
when it clearly appeared that they      
originally contained lagoons1 since     
filled up with sediment3 when there     
were not good grounds for this belief1  
they have been left uncoloured4    ,the 
pale blue colour represented by 7#b7    
represents barrier-reefs4  ,the most    
obvious character of reefs of this class
 is the broad and  deep-water moat      
within the reef3 but this1 like the     
lagoons of small  atolls1 is liable to  
become filled up with detritus and with 
reefs of  delicately branched corals3   
when1 therefore1 a reef round the entire
  circumference of an island extends    
very far into a profoundly deep sea1  so

 that it can hardly be confounded with a
 fringing-reef which must  rest on a    
foundation of rock within a small depth1
 it has been coloured  pale blue1       
although it does not include a          
deep-water moat3 but this has  only been
 done rarely1 and each case is          
distinctly mentioned in the  ,appendix4 
,the red colour 7#d7 represents reefs   
fringing the land quite closely  where  
the sea is deep1 and where the bottom is
 gently inclined  extending to a        
moderate distance from it1 but not      
having a deep-water  moat or lagoon-like
 space parallel to the shore4 ,it must  
be remembered  that fringing-reefs are  
frequently breached in front of rivers  
and  valleys by deepish channels1 where 
mud has been deposited4 ,a space of     
thirty miles in width has been coloured 
round or in front of the reefs  of each 
class1 in order that the colours might  
be conspicuous on the  appended map1    
which is reduced to so small a scale4   
,the vermillion spots1 and streaks 7#a7 

represent volcanoes now in  action1 or  
historically known to have been so4     
,they are chiefly laid  down from ,von  
,buch's work on the ,canary ,islands2   
and my reasons for  making a few        
alterations are given in the note       
below4#a     #a ,i have also made       
considerable use of the geological part 
of   ,berghaus' 8,physical ,atlas40     
,beginning at the eastern side of the   
,pacific1 ,i have added to the number of
 the volcanoes in the southern   part of
 the ,cordillera1 and have coloured     
,juan ,fernandez according to           
observations collected during the voyage
 of the ,beagle 78,geological           
,transactions10 volume v41 page #fja47  
,i have added a volcano to   ,albemarle 
,island1 one of the ,galapagos          
,archipelago 7the author's   8,journal  
of ,researches10 page #deg74 ,in the    
,sandwich group there are no   active   
volcanoes1 except at ,hawaii2 but the   
,rev4 ,w4 ,ellis informs me1   there are
 streams of lava apparently modern on   

,maui1 having a very   recent           
appearance1 which can be traced to the  
craters whence they   flowed4 ,the same 
gentleman informs me1 that there is no  
reason to   believe that any active     
volcano exists in the ,society          
,archipelago2 nor   are there any known 
in the ,samoa or ,navigator group1      
although some of   the streams of lava  
and craters there appear recent4 ,in the
 ,friendly   group1 the ,rev4 ,j4       
,williams says 78,narrative of          
,missionary   ,enterprise10 page #bi7   
that ,toofoa and ,proby ,islands are    
active   volcanoes4 ,i infer from       
,hamilton's 8,voyage in the #8,pandora'0
 7,page   #ie71 that ,proby ,island is  
synonymous with ,onouafou1 but ,i have  
not   ventured to colour it4 ,there can 
be no doubt respecting ,toofoa1 and     
,captain ,edwards 7,von ,buch1 page     
#chf7 found the lava of recent eruption 
at ,amargura still smoking4 ,berghaus   
marks four active volcanoes   actually  
within the ,friendly group2 but ,i do   

not know on what   authority3 ,i may    
mention that ,maurelle describes ,latte 
as having a   burnt-up appearance3 ,i   
have marked only ,toofoa and ,amargura4 
,south of   the ,new ,hebrides lies     
,matthews ,rock1 which is drawn and     
described as   an active crater in the  
8,voyage of the ,astrolabe40 ,between it
 and   the volcano on the eastern side  
of ,new ,zealand1 lies ,brimstone       
,island1   which from the high          
temperature of the water in the crater1 
may be   ranked as active 7,berghaus    
8,vorbemerk10 ,,ii ,lief4 ,s4 #ef74     
,malte ,brun1   volume xii41 page #bca1 
says that there is a volcano near port  
,st4   ,vincent in ,new ,caledonia4 ,i  
believe this to be an error1 arising    
from   a smoke seen on the opposite     
coast by ,cook 78,second ,voyage10      
volume   ii41 page #bc7 which smoke went
 out at night4 ,the ,mariana ,islands1  
especially the northern ones1 contain   
many craters 7see ,freycinet's          
8,hydrog4 ,descript407 which are not    

active4 ,von ,buch1 however1 states     
7page #dfb7 on the authority of ,la     
,peyrouse1 that there are no less   than
 seven volcanoes between these islands  
and ,japan4 ,gemelli ,creri             
7,churchill's 8,collect40 volume iv41   
page #deh71 says there are two   active 
volcanoes in latitude #bc #cj1 and in   
latitude #bd3 but ,i have   not coloured
 them4 ,from the statements in          
,beechey's 8,voyage0 7page   #eah1 #dto 
edition7 ,i have coloured one in the    
northern part of the   ,bonin group4 ,m4
 ,s4 ,julien has clearly made out from  
,chinese   manuscripts not very ancient 
78,comptes ,rendus10 #ahdj1 page #hcb71 
that   there are two active volcanoes on
 the eastern side of ,formosa4 ,in      
,torres ,straits1 on ,cap ,island 7#i   
#dh ,s41 #adb #ci ,e47 a volcano was    
seen burning with great violence in     
#agic by ,captain ,bampton 7see         
,introduction to ,flinders' 8,voyage10  
page #da74 ,mr4 ,m',clelland 7,report   
of ,committee for investigating ,coal in

 ,india1 page #ci7 has shown that   the 
volcanic band passing through ,barren   
,island must be extended   northwards4  
,it appears by an old chart1 that       
,cheduba was once an   active volcano   
7see also 8,silliman's ,north ,american 
,journal01 volume   xxxviii41 page      
#che74 ,in ,berghaus' 8,physical        
,atlas10 #ahdj1 ,no4 #g of   ,geological
 ,part1 a volcano on the coast of       
,pondicherry is said to have   burst    
forth in #ageg4 ,ordinaire 78,hist4     
,nat4 des ,volcans10 page #bah7   says  
that there is one at the mouth of the   
,persian ,gulf1 but ,i have   not       
coloured it1 as he gives no particulars4
 ,a volcano in ,amsterdam1   or ,st4    
,paul's1 in the southern part of the    
,indian ,ocean1 has been seen   78,naut4
 ,mag40 #ahch1 page #hdb7 in action4    
,dr4 ,j4 ,allan1 of ,forres1   informs  
me in a letter1 that when he was at     
,joanna1 he saw at night   flames       
apparently volcanic1 issuing from the   
chief ,comoro ,island1 and   that the   

,arabs assured him that they were       
volcanic1 adding that the   volcano     
burned more during the wet season4 ,i   
have marked this as a   volcano1 though 
with some hesitation1 on account of the 
possibility of   the flame arising from 
gaseous sources4      ,the uncoloured   
coasts consist1 first and chiefly1 of   
those1 where  there are no coral-reefs1 
or such small portions as to be quite   
insignificant4 ,secondly1 of those      
coasts where there are reefs1 but  where
 the sea is very shallow1 for in this   
case the reefs generally lie  far from  
the land1 and become very irregular1 in 
their forms3 where  they have not become
 irregular1 they have been coloured4    
thirdly1 if ,i  had the means of        
ascertaining the fact1 ,i should not    
colour a reef  merely coating the edges 
of a submarine crater1 or of a level    
submerged  bank2 for such superficial   
formations differ essentially1 even when
 not  in external appearance1 from reefs
 whose foundations as well as           

superficies have been wholly formed by  
the growth of coral4 ,fourthly1  in the 
,red ,sea1 and within some parts of the 
,east ,indian ,archipelago  7if the     
imperfect charts of the latter can be   
trusted71 there are many  scattered     
reefs1 of small size1 represented in the
 chart by mere dots1  which rise out of 
deep water3 these cannot be arranged    
under either of  the three classes3 in  
the ,red ,sea1 however1 some of these   
little reefs1  from their position1 seem
 once to have formed parts of a         
continuous  barrier4 ,there exist1 also1
 scattered in the open ocean1 some      
linear  and irregularly formed strips of
 coral-reef1 which1 as shown in the     
last chapter1 are probably allied in    
their origin to atolls2 but as  they do 
not belong to that class1 they have not 
been coloured2 they are  very few in    
number and of insignificant dimensions4 
,lastly1 some reefs  are left uncoloured
 from the want of information respecting
 them1 and  some because they are of an 

intermediate structure between the      
barrier  and fringing classes4 ,the     
value of the map is lessened1 in        
proportion  to the number of reefs which
 ,i have been obliged to leave          
uncoloured1  although1 in a theoretical 
point of view1 few of them present any  
great  difficulty3 but their number is  
not very great1 as will be found by     
comparing the map with the statements in
 the ,appendix4 ,i have  experienced    
more difficulty in colouring            
fringing-reefs than in  colouring       
barrier-reefs1 as the former1 from their
 much less  dimensions1 have less       
attracted the attention of navigators4  
,as ,i have  had to seek my information 
from all kinds of sources1 and often    
from  indirect ones1 ,i do not venture  
to hope that the map is free from many  
errors4 ,nevertheless1 ,i trust it will 
give an approximately correct  view of  
the general distribution of the         
coral-reefs over the whole  world 7with 
the exception of some fringing-reefs on 

the coast of  ,brazil1 not included     
within the limits of the map71 and of   
their  arrangement into the three great 
classes1 which1 though necessarily  very
 imperfect from the nature of the       
objects classified1 have been  adopted  
by most voyagers4 ,i may further remark1
 that the dark blue  colour represents  
land entirely composed of coral-rock2   
the pale blue1  land with a wide and    
thick border of coral-rock2 and the red1
 a mere  narrow fringe of coral-rock4   
,looking now at the map under the       
theoretical point of view indicated in  
the last chapter1 the two blue tints    
signify that the foundations of  the    
reefs thus coloured have subsided to a  
considerable amount1 at a  slower rate  
than that of the upward growth of the   
corals1 and that  probably in many cases
 they are still subsiding4 ,the red     
signifies that  the shores which support
 fringing-reefs have not subsided 7at   
least to  any considerable amount1 for  
the effects of a subsidence on a small  

scale would in no case be               
distinguishable72 but that they have    
remained  nearly stationary since the   
period when they first became fringed by
  reefs2 or that they are now rising or 
have been upraised1 with new  lines of  
reefs successively formed on them3 these
 latter alternatives  are obviously     
implied1 as newly formed lines of shore1
 after elevations  of the land1 would be
 in the same state with respect to the  
growth of  fringing-reefs1 as stationary
 coasts4 ,if during the prolonged       
subsidence of a shore1 coral-reefs grew 
for the first time on it1 or if  an old 
barrier-reef were destroyed and         
submerged1 and new reefs became         
attached to the land1 these would       
necessarily at first belong to the      
fringing class1 and1 therefore1 be      
coloured red1 although the coast was    
sinking3 but ,i have no reason to       
believe1 that from this source of       
error1 any coast has been coloured      
wrongly with respect to movement        

indicated4 ,well characterised atolls   
and encircling barrier-reefs1  where    
several occur in a group1 or a single   
barrier-reef if of large  dimensions1   
leave scarcely any doubt on the mind    
respecting the  movement by which they  
have been produced2 and even a small    
amount of  subsequent elevation is soon 
betrayed4 ,the evidence from a single   
atoll  or a single encircling           
barrier-reef1 must be received with some
  caution1 for the former may possibly  
be based upon a submerged crater  or    
bank1 and the latter on a submerged     
margin of sediment1 or of  worn-down    
rock4 ,from these remarks we may with   
greater certainty infer  that the       
spaces1 especially the larger ones1     
tinted blue in the map1  have subsided1 
than that the red spaces have remained  
stationary1 or  have been upraised4     
,on the grouping of the different       
classes of reefs4--,having made these   
preliminary remarks1 ,i will consider   
first how far the grouping of the       

different kinds of coral-islands and    
reefs is corroborative of the  truth of 
the theory4 ,a glance at the map shows  
that the reefs1 coloured  blue and red1 
produced under widely different         
conditions1 are not  indiscriminately   
mixed together4 ,atolls and             
barrier-reefs1 on the other  hand1 as   
may be seen by the two blue tints1      
generally lie near each  other2 and this
 would be the natural result of both    
having been  produced during the        
subsidence of the areas in which they   
stand4 ,thus1  the largest group of     
encircled islands is that of the        
,society  ,archipelago2 and these       
islands are surrounded by atolls1 and   
only  separated by a narrow space from  
the large group of ,low atolls4 ,in the 
midst of the ,caroline atolls1 there are
 three fine encircled islands4  ,the    
northern point of the barrier-reef of   
,new ,caledonia seems itself1  as before
 remarked1 to form a complete large     
atoll4 ,the great  ,australian barrier  

is described as including both atolls   
and small  encircled islands4 ,captain  
,king#b mentions many atoll-formed and  
encircling coral-reefs1 some of which   
lie within the barrier1 and  others may 
be said 7for instance between latitude  
#af and #ac7 to form  part of it4       
,flinders#c has described an            
atoll-formed reef in latitude  #aj1     
seven miles long and from one to three  
broad1 resembling a boot in  shape1 with
 apparently very deep water within4     
,eight miles westward of  this1 and     
forming part of the barrier1 lie the    
,murray ,islands1 which  are high and   
are encircled4 ,in the ,corallian ,sea1 
between the two great  barriers of      
,australia and ,new ,caledonia1 there   
are many low islets and  coral-reefs1   
some of which are annular1 or horse-shoe
 shaped4 ,observing  the smallness of   
the scale of the map1 the parallels of  
latitude being  nine hundred miles      
apart1 we see that none of the large    
groups of reefs  and islands supposed to

 have been produced by long-continued   
subsidence1 lie near extensive lines of 
coast coloured red1 which are  supposed 
to have remained stationary since the   
growth of their reefs1  or to have been 
upraised and new lines of reefs formed  
on them4 ,where  the red and blue       
circles do occur near each other1 ,i am 
able1 in  several instances1 to show    
that there have been oscillations of    
level1  subsidence having preceded the  
elevation of the red spots2 and         
elevation having preceded the subsidence
 of the blue spots3 and in this  case   
the juxtaposition of reefs belonging to 
the two great types of  structure is    
little surprising4 ,we may1 therefore1  
conclude that the  proximity in the same
 areas of the two classes of reefs1     
which owe  their origin to the          
subsidence of the earth's crust1 and    
their  separation from those formed     
during its stationary or uprising       
condition1 holds good to the full       
extent1 which might have been           

anticipated by our theory4     #b       
,sailing directions1 appended to volume 
ii4 of his 8,surveying   ,voyage to     
,australia40       #c 8,voyage to ,terra
 ,australis10 volume ii4 page #ccf4     
,as groups of atolls have originated in 
the upward growth1 at each fresh        
sinking of the land1 of those reefs     
which primarily fringed the shores  of  
one great island1 or of several smaller 
ones2 so we might expect  that these    
rings of coral-rock1 like so many rude  
outline charts1 will  still retain some 
traces of the general form1 or at least 
general  range1 of the land1 round which
 they were first modelled4 ,that this is
  the case with the atolls in the       
,southern ,pacific as far as their range
  is concerned1 seems highly probable1  
when we observe that the three          
principal groups are directed in        
north-west and south-east lines1 and    
that nearly all the land in the ,s4     
,pacific ranges in this same  direction2
 namely1 ,n4 ,western ,australia1 ,new  

,caledonia1 the northern  half of ,new  
,zealand1 the ,new ,hebrides1 ,saloman1 
,navigator1 ,society1  ,marquesas1 and  
,austral archipelagoes3 in the ,northern
 ,pacific1 the  ,caroline atolls abut   
against the north-west line of the      
,marshall  atolls1 much in the same     
manner as the east and west line of     
islands  from ,ceram to ,new ,britain do
 on ,new ,ireland3 in the ,indian ,ocean
 the  ,laccadive and ,maldiva atolls    
extend nearly parallel to the western   
and  mountainous coast of ,india4 ,in   
most respects1 there is a perfect       
resemblance with ordinary islands in the
 grouping of atolls and in  their form3 
thus the outline of all the larger      
groups is elongated2 and  the greater   
number of the individual atolls are     
elongated in the same  direction with   
the group1 in which they stand4 ,the    
,chagos group is less  elongated than is
 usual with other groups1 and the       
individual atolls in  it are likewise   
but little elongated2 this is strikingly

 seen by  comparing them with the       
neighbouring ,maldiva atolls4 ,in the   
,marshall  and ,maldiva archipelagoes1  
the atolls are ranged in two parallel   
lines1  like the mountains in a great   
double mountain-chain4 ,some of the     
atolls1 in the larger archipelagoes1    
stand so near to each other1 and  have  
such an evident relationship in form1   
that they compose little  sub-groups3 in
 the ,caroline ,archipelago1 one such   
sub-group consists of  ,pouynipte1 a    
lofty island encircled by a             
barrier-reef1 and separated  by a       
channel only four miles and a half wide 
from ,andeema atoll1 with a  second     
atoll a little further off4 ,in all     
these respects an examination  of a     
series of charts will show how perfectly
 groups of atolls resemble  groups of   
common islands4    ,on the direct       
evidence of the blue spaces in the map  
having subsided  during the upward      
growth of the reefs so coloured1 and of 
the red  spaces having remained         

stationary1 or having been              
upraised4--,with  respect to subsidence1
 ,i have shown in the last chapter1 that
 we cannot  expect to obtain in         
countries inhabited only by             
semi-civilised races1  demonstrative    
proofs of a movement1 which invariably  
tends to conceal  its own evidence4 ,but
 on the coral-islands supposed to have  
been  produced by subsidence1 we have   
proofs of changes in their external     
appearance--of a round of decay and     
renovation--of the last vestiges of     
land on some--of its first commencement 
on others3 we hear of storms  desolating
 them to the astonishment of their      
inhabitants3 we know by  the great      
fissures with which some of them are    
traversed1 and by the  earthquakes felt 
under others1 that subterranean         
disturbances of some  kind are in       
progress4 ,these facts1 if not directly 
connected with  subsidence1 as ,i       
believe they are1 at least show how     
difficult it would  be to discover      

proofs of such movement by ordinary     
means4 ,at ,keeling  atoll1 however1 ,i 
have described some appearances1 which  
seem directly  to show that subsidence  
did take place there during the late    
earthquakes4 ,vanikoro1 according to    
,chevalier ,dillon1#d is often          
violently shaken by earthquakes1 and    
there1 the unusual depth of the  channel
 between the shore and the reef1--the   
almost entire absence of  islets on the 
reef1-- its wall-like structure on the  
inner side1 and the  small quantity of  
low alluvial land at the foot of the    
mountains1 all  seem to show that this  
island has not remained long at its     
present  level1 with the lagoon-channel 
subjected to the accumulation of        
sediment1 and the reef to the wear and  
tear of the breakers4 ,at the  ,society 
,archipelago1 on the other hand1 where a
 slight tremor is only  rarely felt1 the
 shoaliness of the lagoon-channels round
 some of the  islands1 the number of    
islets formed on the reefs of others1   

and the  broad belt of low land at the  
foot of the mountains1 indicate that1   
although there must have been great     
subsidence to have produced the         
barrier-reefs1 there has since elapsed a
 long stationary period4#e     #d ,see  
,captain ,dillon's 8,voyage in search of
 ,la ,peyrouse40 ,m4 ,cordier   in his  
8,report on the ,voyage of the          
#8,astrolabe'0 7page cxi41 volume   i471
 speaking of ,vanikoro1 says the shores 
are surrounded by reefs of   madrepore1 
8qu'on assure tre de formation          
tout-a-fait moderne40 ,i   have in vain 
endeavoured to learn some further       
particulars about this   remarkable     
passage4 ,i may here add1 that according
 to our theory1 the   island of         
,pouynipte 7,plate ,i41 ,figure #g71 in 
the ,caroline   ,archipelago1 being     
encircled by a barrier-reef1 must have  
subsided4 ,in   the 8,new ,s4 ,wales    
,lit4 ,advert40 ,february #ahce 7which  
,i have seen   through the favour of    
,dr4 ,lloghtsky71 there is an account of

 this   island 7subsequently confirmed  
by ,mr4 ,campbell71 in which it is said1
   8,at the ,n4,e4 end1 at a place      
called ,tamen1 there are ruins of a     
town1   now only accessible by boats1   
the waves reaching to the steps of   the
 houses40 ,judging from this passage1   
one would be tempted to   conclude that 
the island must have subsided1 since    
these houses were   built4 ,i may1 also1
 here append a statement in ,malte ,brun
 7volume ix41   page #gge1 given without
 any authority71 that the sea gains in  
an   extraordinary manner on the coast  
of ,cochin ,china1 which lies in front  
and near the subsiding coral-reefs in   
the ,china ,sea3 as the coast is        
granitic1 and not alluvial1 it is       
scarcely possible that the              
encroachment of the sea can be owing to 
the washing away of the land2   and if  
so1 it must be due to subsidence4       
#e ,mr4 ,couthouy states 78,remarks10   
page #dd7 that at ,tahiti and ,eimeo    
the space between the reef and the shore

 has been nearly filled up by   the     
extension of those coral-reefs1 which   
within most barrier-reefs   merely      
fringe the land4 ,from this             
circumstance1 he arrives at the same    
conclusion as ,i have done1 that the    
,society ,islands since their           
subsidence1 have remained stationary    
during a long period2 but he   further  
believes that they have recently        
commenced rising1 as well as   the whole
 area of the ,low ,archipelago4 ,he does
 not give any detailed   proofs         
regarding the elevation of the ,society 
,islands1 but ,i shall   refer to this  
subject in another part of this chapter4
 ,before making   some further comments1
 ,i may observe how satisfactory it is  
to me1 to   find ,mr4 ,couthouy         
affirming1 that 8having personally      
examined a large   number of            
coral-islands1 and also residing eight  
months among the   volcanic class1      
having shore and partially encircling   
reefs1 ,i may be   permitted to state   

that my own observations have impressed 
a   conviction of the correctness of the
 theory of ,mr4 ,darwin40        ,this  
gentleman believes1 that subsequently to
 the subsidence by      which the atolls
 in the ,low ,archipelago were produced1
 the whole      area has been elevated  
to the amount of a few feet2 this would 
indeed be a remarkable fact2 but as far 
as ,i am able to judge1 the      grounds
 of his conclusion are not sufficiently 
strong4 ,he states      that he found in
 almost every atoll which he visited1   
the shores of      the lagoon raised    
from eighteen to thirty inches above the
      sea-level1 and containing imbedded
 ,tridacnae and corals standing as      
they grew2 some of the corals were dead 
in their upper parts1 but      below a  
certain line they continued to flourish4
 ,in the lagoons1      also1 he         
frequently met with clusters of         
,madrepore1 with their      extremities 
standing from one inch to a foot above  
the surface of      the water4 ,now1    

these appearances are exactly what ,i   
should have      expected1 without any  
subsequent elevation having taken place2
 and      ,i think ,mr4 ,couthouy has   
not borne in mind the indisputable fact1
      that corals1 when constantly      
bathed by the surf1 can exist at a      
higher level than in quite tranquil     
water1 as in a lagoon4 ,as long1        
therefore1 as the waves continued at low
 water to break entirely      over parts
 of the annular reef of an atoll1       
submerged to a small      depth1 the    
corals and shells attached on these     
parts might continue      living at a   
level above the smooth surface of the   
lagoon1 into      which the waves       
rolled2 but as soon as the outer edge of
 the reef      grew up to its utmost    
possible height1 or if the reef were    
very      broad nearly to that height1  
the force of the breakers would be      
checked1 and the corals and shells on   
the inner parts near the      lagoon    
would occasionally be left dry1 and thus

 be partially or      wholly destroyed4 
,even in atolls1 which have not lately  
subsided1      if the outer margin of   
the reef continued to increase in       
breadth      seaward 7each fresh zone of
 corals rising to the same vertical     
height as at ,keeling atoll71 the line  
where the waves broke most      heavily 
would advance outwards1 and therefore   
the corals1 which      when living near 
the margin1 were washed by the breaking 
waves      during the whole of each     
tide1 would cease being so1 and would   
therefore be left on the backward part  
of the reef standing exposed      and   
dead4 ,the case of the madrepores in the
 lagoons with the tops      of their    
branches exposed1 seems to be an        
analogous fact1 to the      great fields
 of dead but upright corals in the      
lagoon of ,keeling      atoll2 a        
condition of things which ,i have       
endeavoured to show1 has      resulted  
from the lagoon having become more and  
more enclosed and      choked up with   

reefs1 so that during high winds1 the   
rising of the      tide 7as observed by 
the inhabitants7 is checked1 and the    
corals1      which had formerly grown to
 the greatest possible height1 are      
occasionally exposed1 and thus are      
killed3 and this is a condition      of 
things1 towards which almost every atoll
 in the intervals of its      subsidence
 must be tending4 ,or if we look to the 
state of an atoll      directly after a 
subsidence of some fathoms1 the waves   
would roll      heavily over the entire 
circumference of the reef1 and the      
surface      of the lagoon would1 like  
the ocean1 never be quite at rest1 and  
therefore the corals in the lagoon1 from
 being constantly laved by      the     
rippling water1 might extend their      
branches to a little greater      height
 than they could1 when the lagoon became
 enclosed and      protected4 ,christmas
 atoll 7#b ,n4 latitude7 which has a    
very      shallow lagoon1 and differs in
 several respects from most atolls1     

possibly may have been elevated         
recently2 but its highest part          
appears 7,couthouy1 page #df7 to be only
 ten feet above the      sea-level4 ,the
 facts of a second class1 adduced by    
,mr4 ,couthouy1 in      support of the  
alleged recent elevation of the ,low    
,archipelago1 are      not all          
7especially those referring to a shelf  
of rock7 quite      intelligible to me2 
he believes that certain enormous       
fragments of      rock on the reef1 must
 have been moved into their present     
position1      when the reef was at a   
lower level2 but here again the force of
 the      breakers on any inner point of
 the reef being diminished by its       
outward growth without any change in its
 level1 has not1 ,i think1      been    
borne in mind4 ,we should1 also1 not    
overlook the occasional      agency of  
waves caused by earthquakes and         
hurricanes4 ,mr4 ,couthouy      further 
argues1 that since these great fragments
 were deposited and      fixed on the   

reef1 they have been elevated2 he infers
 this from the      greatest amount of  
erosion not being near their bases1     
where they      are unceasingly washed  
by the reflux of the tides1 but at some 
height on their sides1 near the line of 
high-water mark1 as shown      in an    
accompanying diagram4 ,my former remark 
again applies here1      with this      
further observation1 that as the waves  
have to roll over      a wide space of  
reef before they reach the fragments1   
their force      must be greatly        
increased with the increasing depth of  
water as the      tide rises1 and       
therefore ,i should have expected that  
the chief      line of present erosion  
would have coincided with the line of   
high-water mark2 and if the reef had    
grown outwards1 that there      would   
have been lines of erosion at greater   
heights4 ,the      conclusion1 to which 
,i am finally led by the interesting    
observations of ,mr4 ,couthouy is1 that 
the atolls in the ,low      ,archipelago

 have1 like the ,society ,islands1      
remained at a      stationary level for 
a long period3 and this probably is the 
ordinary course of events1 subsidence   
supervening after long      intervals of
 rest4      ,turning now to the red     
colour2 as on our map1 the areas which  
have sunk  slowly downwards to great    
depths are many and large1 we might     
naturally  have been led to conjecture1 
that with such great changes of level in
  progress1 the coasts which have been  
fringed probably for ages 7for we  have 
no reason to believe that coral-reefs   
are of short duration71  would not have 
remained all this time stationary1 but  
would frequently  have undergone        
movements of elevation4 ,this           
supposition1 we shall  immediately see1 
holds good to a remarkable extent2 and  
although a  stationary condition of the 
land can hardly ever be open to proof1  
from  the evidence being only negative1 
we are1 in some degree1 enabled to      
ascertain the correctness of the parts  

coloured red on the map1 by the  direct 
testimony of upraised organic remains of
 a modern date4 ,before  going into the 
details on this head 7printed in small  
type71 ,i may  mention1 that when       
reading a memoir on coral formations by 
,,mm4 ,quoy and  ,gaimard#f ,i was      
astonished to find1 for ,i knew that    
they had crossed  both the ,pacific and 
,indian ,oceans1 that their descriptions
 were  applicable only to reefs of the  
fringing class2 but my astonishment     
ended satisfactorily1 when ,i discovered
 that1 by a strange chance1 all  the    
islands which these eminent naturalists 
had visited1 though several  in number1 
namely1 the ,mauritius1 ,timor1 ,new    
,guinea1 the ,mariana1 and  ,sandwich   
,archipelagoes1 could be shown by their 
own statements to have  been elevated   
within a recent geological era4     #f  
8,annales des ,sciences ,nat40 tom4 vi41
 page #bgi1 etc4      ,in the eastern   
half of the ,pacific1 the ,sandwich     
,islands are all  fringed1 and almost   

every naturalist who has visited them1  
has remarked  on the abundance of       
elevated corals and shells1 apparently  
identical  with living species4 ,the    
,rev4 ,w4 ,ellis informs me1 that he has
 noticed  round several parts of        
,hawaii1 beds of coral-detritus1 about  
twenty  feet above the level of the sea1
 and where the coast is low they extend 
far inland4 ,upraised coral-rock forms a
 considerable part of the  borders of   
,oahu2 and at ,elizabeth ,island#g it   
composes three strata1  each about ten  
feet thick4 ,nihau1 which forms the     
northern1 as ,hawaii  does the southern 
end of the group 7#cej miles in length71
 likewise  seems to consist of coral and
 volcanic rocks4 ,mr4 ,couthouy#h has   
lately described with interesting       
details1 several upraised beaches1      
ancient reefs with their surfaces       
perfectly preserved1 and beds of  recent
 shells and corals1 at the islands of   
,maui1 ,morokai1 ,oahu1 and  ,tauai 7or 
,kauai7 in this group4 ,mr4 ,pierce1 an 

intelligent resident at  ,oahu1 is      
convinced1 from changes which have taken
 place within his  memory1 during the   
last sixteen years1 8that the elevation 
is at  present going forward at a very  
perceptible rate40 ,the natives at      
,kauai  state that the land is there    
gaining rapidly on the sea1 and ,mr4    
,couthouy has no doubt1 from the nature 
of the strata1 that this has  been      
effected by an elevation of the land4   
#g 8,zoology of ,captain ,beechey's     
,voyage10 page #agf4 ,see also ,,mm4    
,quoy   and ,gaimard in 8,annales de    
,scien4 ,nat40 tom4 vi4       #h        
8,remarks on ,coral ,formations10 page  
#ea4      ,in the southern part of the  
,low ,archipelago1 ,elizabeth ,island is
  described by ,captain ,beechey1#i as  
being quite flat1 and about eighty  feet
 in height2 it is entirely composed of  
dead corals1 forming a  honeycombed1 but
 compact rock4 ,in cases like this1 of  
an island having  exactly the           
appearance1 which the elevation of any  

one of the smaller  surrounding atolls  
with a shallow lagoon would present1 one
 is led to  conclude 7with little better
 reason1 however1 than the improbability
 of  such small and low fabrics lasting1
 for an immense period1 exposed to  the 
many destroying agents of nature71 that 
the elevation has taken  place at an    
epoch not geologically remote4 ,when    
merely the surface of  an island of     
ordinary formation is strewed with      
marine bodies1 and that  continuously1  
or nearly so1 from the beach to a       
certain height1 and not  above that     
height1 it is exceedingly improbable    
that such organic  remains1 although    
they may not have been specially        
examined1 should  belong to any ancient 
period4 ,it is necessary to bear these  
remarks in  mind1 in considering the    
evidence of the elevatory movements in  
the  ,pacific and ,indian ,oceans1 as it
 does not often rest on specific        
determinations1 and therefore should be 
received with caution4 ,six of  the     

,cook and ,austral ,islands 7,s4,w4 of  
the ,society group71 are  fringed2 of   
these1 five were described to me by the 
,rev4 ,j4 ,williams1  as formed of      
coral-rock1 associated with some basalt 
in ,mangaia71 and  the sixth as lofty   
and basaltic4 ,mangaia is nearly three  
hundred feet  high1 with a level summit2
 and according to ,mr4 ,s4 ,wilson#aj it
 is an  upraised reef2 8and there are in
 the central hollow1 formerly the bed   
of the lagoon1 many scattered patches of
 coral-rock1 some of them  raised to a  
height of forty feet40 ,these knolls of 
coral-rock were  evidently once separate
 reefs in the lagoon of an atoll4 ,mr4  
,martens1  at ,sydney1 informed me that 
this island is surrounded by a          
terrace-like  plain at about the height 
of a hundred feet1 which probably marks 
a  pause in its elevation4 ,from these  
facts we may infer1 perhaps1 that  the  
,cook and ,austral ,islands have been   
upheaved at a period probably  not very 
remote4     #i ,beechey's 8,voyage in   

the ,pacific10 page #df1 #dto edition4  
#aj ,couthouy's 8,remarks10 page #cd4   
,savage ,island 7,s4,e4 of the ,friendly
 group71 is about forty feet in  height4
 ,forster#aa describes the plants as    
already growing out of  the dead1 but   
still upright and spreading trees of    
coral2 and the  younger ,forster#ab     
believes that an ancient lagoon is now  
represented  by a central plain2 here we
 cannot doubt that the elevatory forces 
have  recently acted4 ,the same         
conclusion may be extended1 though with 
somewhat less certainty1 to the islands 
of the ,friendly ,group1 which  have    
been well described in the second and   
third voyages of ,cook4 ,the  surface of
 ,tongatabou is low and level1 but with 
some parts a hundred  feet high2 the    
whole consists of coral-rock1 8which yet
 shows the  cavities and irregularities 
worn into it by the action of the       
tides40#ac ,on ,eoua the same           
appearances were noticed at an elevation
  of between two hundred and three      

hundred feet4 ,vavao1 also1 at the      
opposite or northern end of the group1  
consists1 according to the ,rev4  ,j4   
,williams1 of coral-rock4 ,tongatabou1  
with its northern extensive  reefs1     
resembles either an upraised atoll with 
one half originally  imperfect1 or one  
unequally elevated2 and ,anamouka1 an   
atoll equally  elevated4 ,this latter   
island contains#ad in its centre a      
salt-water  lake1 about a               
mile-and-a-half in diameter1 without any
 communication  with the sea1 and around
 it the land rises gradually like a     
bank2 the  highest part is only between 
twenty and thirty feet2 but on this     
part1  as well as on the rest of the    
land 7which1 as ,cook observes1 rises   
above the height of true                
lagoon-islands71 coral-rock1 like that  
on the  beach1 was found4 ,in the       
,navigator ,archipelago1 ,mr4           
,couthouy#ae  found on ,manua many and  
very large fragments of coral at the    
height of  eighty feet1 8on a steep     

hill-side1 rising half a mile inland    
from a  low sandy plain abounding in    
marine remains40 ,the fragments were    
embedded in a mixture of decomposed lava
 and sand4 ,it is not stated  whether   
they were accompanied by shells1 or     
whether the corals  resembled recent    
species2 as these remains were embedded 
they possibly  may belong to a remote   
epoch2 but ,i presume this was not the  
opinion of  ,mr4 ,couthouy4 ,earthquakes
 are very frequent in this archipelago4 
#aa 8,observations made during ,voyage  
round the ,world10 page #adg4       #ab 
8,voyage10 volume ii41 page #afc4       
#ac ,cook's 8,third ,voyage0 7#dto      
edition71 volume i41 page #cad4         
#ad ,ibid41 volume i41 page #bce4       
#ae 8,remarks on ,coral-,formations10   
page #ej4      ,still proceeding        
westward we come to the ,new ,hebrides2 
on these  islands1 ,mr4 ,g4 ,bennett    
7author of 8,wanderings in ,new ,south  
,wales071  informs me he found much     
coral at a great altitude1 which he     

considered  of recent origin4           
,respecting ,santa ,cruz1 and the       
,salomon  ,archipelago1 ,i have no      
information2 but at ,new ,ireland1 which
 forms  the northern point of the latter
 chain1 both ,labillardire and ,lesson  
have described large beds of an         
apparently very modern madreporitic     
rock1 with the form of the corals little
 altered4 ,the latter author#af  states 
that this formation composes a newer    
line of coast1 modelled  round an       
ancient one4 ,there only remains to be  
described in the  ,pacific1 that curved 
line of fringed islands1 of which the   
,marianas  form the main part4 ,of these
 ,guam1 ,rota1 ,tiniam1 ,saypan1 and    
some  islets farther north1 are         
described by ,quoy and ,gaimard1#ag and 
,chamisso1#ah as chiefly composed of    
madreporitic limestone1 which  attains a
 considerable elevation1 and is in      
several cases worn into  successively   
rising cliffs3 the two former           
naturalists seem to have  compared the  

corals and shells with the existing     
ones1 and state that  they are of recent
 species4 ,fais1 which lies in the      
prolonged line of  the ,marianas1 is the
 only island in this part of the sea    
which is  fringed2 it is ninety feet    
high1 and consists entirely of          
madreporitic  rock4#ai     #af 8,voyage 
de la #8,coquille'10 ,part4 ,zoolog4    
#ag ,freycinet's 8,voyage autour du     
,monde40 ,see also the                  
8,hydrographical ,memoir10 page #bae4   
#ah ,kotzebue's 8,first ,voyage40       
#ai ,lutk's 8,voyage10 volume ii41 page 
#cjd4      ,in the ,east ,indian        
,archipelago1 many authors have recorded
 proofs of  recent elevation4 ,m4       
,lesson#bj states1 that near ,port      
,dory1 on the  north coast of ,new      
,guinea1 the shores are flanked1 to the 
height of #aej  feet1 by madreporitic   
strata of modern date4 ,he mentions     
similar  formations at ,waigiou1        
,amboina1 ,bourou1 ,ceram1 ,sonda1 and  
,timor3 at  this latter place1 ,,mm4    

,quoy and ,gaimard#ba have likewise     
described the  primitive rocks1 as      
coated to a considerable height with    
coral4 ,some  small islets eastward of  
,timor are said in ,kolff's             
8,voyage10#bb to  resemble small coral  
islets upraised some feet above the sea4
 ,dr4  ,malcolmson informs me that ,dr4 
,hardie found in ,java an extensive     
formation1 containing an abundance of   
shells1 of which the greater part       
appear to be of existing species4 ,dr4  
,jack#bc has described some  upraised   
shells and corals1 apparently recent1 on
 ,pulo ,nias off  ,sumatra2 and ,marsden
 relates in his history of this great   
island1  that the names of many         
promontories1 show that they were       
originally  islands4 ,on part of the    
west coast of ,borneo and at the ,sooloo
  ,islands1 the form of the land1 the   
nature of the soil1 and the             
water-washed rocks1 present             
appearances#bd 7although it is doubtful 
whether such vague evidence is worthy of

 mention71 of having recently  been     
covered by the sea2 and the inhabitants 
of the ,sooloo ,islands  believe that   
this has been the case4 ,mr4 ,cuming1   
who has lately  investigated1 with so   
much success1 the natural history of the
  ,phillippines1 found near ,cabagan1 in
 ,luzon1 about fifty feet above  the    
level of the ,r4 ,cagayan1 and seventy  
miles from its mouth1 a large  bed of   
fossil shells3 these1 he informs me1 are
 of the same species  with those now    
existing on the shores of the           
neighbouring islands4 ,from  the        
accounts given us by ,captain ,basil    
,hall and ,captain ,beechey#be of  the  
lines of inland reefs1 and walls of     
coral-rock worn into caves1  above the  
present reach of the waves1 at the ,loo 
,choo ,islands1 there  can be little    
doubt that they have been upraised at no
 very remote  period4     #bj ,partie   
,zoolog41 8,voyage de la #8,coquille'40 
#ba 8,ann4 des ,scien4 ,nat40 tom4 vi41 
page #bha4       #bb ,translated by     

,windsor ,earl1 chapters vi41 vii4      
#bc 8,geolog4 ,transact40 #bnd series1  
volume i41 page #djc4 ,on the           
,peninsula of ,malacca1 in front of     
,pinang1 #e #cj ,n41 ,dr4 ,ward         
collected some shells1 which ,dr4       
,malcolmson informs me1 although not    
compared with existing species1 had a   
recent appearance4 ,dr4 ,ward           
describes in this neighbourhood         
78,trans4 ,asiat4 ,soc40 volume xviii41 
part ii41 page #aff7 a single water-worn
 rock1 with a conglomerate of           
sea-shells at its base1 situated six    
miles inland1 which1 according to   the 
traditions of the natives1 was once     
surrounded by the sea4 ,captain   ,low  
has also described 7,ibid41 part i41    
page #aca7 mounds of shells   lying two 
miles inland on this line of coast4     
#bd 8,notices of the ,east ,indian      
,arch40 ,singapore1 #ahbh1 page #f1 and 
,append41 page #dc4       #be ,captain  
,b4 ,hall1 8,voyage to ,loo ,choo10     
,append41 pages xxi4 and   xxv4 ,captain

 ,beechey's 8,voyage10 page #dif4       
,dr4 ,davy#bf describes the northern    
province of ,ceylon as being very  low1 
and consisting of a limestone with      
shells and corals of very  recent       
origin2 he adds1 that it does not admit 
of a doubt that the sea  has retired    
from this district even within the      
memory of man4 ,there is  also some     
reason for believing that the western   
shores of ,india1 north  of ,ceylon1    
have been upraised within the recent    
period4#bg ,mauritius  has certainly    
been upraised within the recent period1 
as ,i have stated  in the chapter on    
fringing-reefs4 ,the northern extremity 
of  ,madagascar is described by ,captain
 ,owen#bh as formed of madreporitic     
rock1 as likewise are the shores and    
outlying islands along an immense  space
 of ,eastern ,africa1 from a little     
north of the equator for nine  hundred  
miles southward4 ,nothing can be more   
vague than the expression  8madreporitic
 rock20 but at the same time it is1 ,i  

think1 scarcely  possible to look at the
 chart of the linear islets1 which rise 
to a  greater height than can be        
accounted for by the growth of coral1 in
  front of the coast1 from the equator  
to #b ,s41 without feeling  convinced   
that a line of fringing-reefs has been  
elevated at a period  so recent1 that no
 great changes have since taken place on
 the surface  of this part of the globe4
 ,some1 also1 of the higher islands of  
madreporitic rock on this coast1 for    
instance ,pemba1 have very singular     
forms1 which seem to show the combined  
effect of the growth of coral  round    
submerged banks1 and their subsequent   
upheaval4 ,dr4 ,allan informs  me that  
he never observed any elevated organic  
remains on the  ,seychelles1 which come 
under our fringed class4     #bf        
8,travels in ,ceylon10 page #ac4 ,this  
madreporitic formation is   mentioned by
 ,m4 ,cordier in his report to the      
,institute 7,may #dth1   #ahci71 on the 
voyage of the 8,chevrette01 as one of   

immense extent1 and   belonging to the  
latest tertiary period4       #bg ,dr4  
,benza1 in his 8,journey through the ,n4
 ,circars0 7the 8,madras   ,lit4 and    
,scient4 ,journ40 volume v47 has        
described a formation with   recent     
fresh-water and marine shells1 occurring
 at the distance of   three or four     
miles from the present shore4 ,dr4      
,benza1 in conversation   with me1      
attributed their position to a rise of  
the land4 ,dr4   ,malcolmson1 however   
7and there cannot be a higher authority 
on the   geology of ,india7 informs me  
that he suspects that these beds may    
have   been formed by the mere action of
 the waves and currents accumulating    
sediment4 ,from analogy ,i should much  
incline to ,dr4 ,benza's opinion4       
#bh ,owen's 8,africa10 volume ii41 page 
#cg1 for ,madagascar2 and for ,s4       
,africa1 volume i41 pages #dab and #dbf4
 ,lieutenant ,boteler's narrative       
contains fuller particulars regarding   
the coral-rock1 volume i41 page   #agd1 

and volume ii41 pages #da and #ed4 ,see 
also ,ruschenberger's 8,voyage   round  
the ,world10 volume i41 page #fj4       
,the nature of the formations round the 
shores of the ,red ,sea1 as  described  
by several authors1 shows that the whole
 of this large area  has been elevated  
within a very recent tertiary epoch4 ,a 
part of this  space in the appended map1
 is coloured blue1 indicating the       
presence of  barrier-reefs3 on which    
circumstance ,i shall presently make    
some  remarks4 ,rppell#bi states that   
the tertiary formation1 of which he  has
 examined the organic remains1 forms a  
fringe along the shores with  a uniform 
height of from thirty and forty feet    
from the mouth of the  ,gulf of ,suez to
 about latitude #bf2 but that south of  
#bf1 the beds  attain only the height of
 from twelve to fifteen feet4 ,this1    
however1  can hardly be quite accurate2 
although possibly there may be a        
decrease  in the elevation of the shores
 in the middle parts of the ,red ,sea1  

for  ,dr4 ,malcolmson 7as he informs me7
 collected from the cliffs of ,camaran  
,island 7latitude #ae #cj ,s47 shells   
and corals1 apparently recent1 at a     
height between thirty and forty feet2   
and ,mr4 ,salt 78,travels in            
,abyssinia07 describes a similar        
formation a little southward on the     
opposite shore at ,amphila4 ,moreover1  
near the mouth of the ,gulf of  ,suez1  
although on the coast opposite to that  
on which ,dr4 ,rppell says  that the    
modern beds attain a height of only     
thirty to forty feet1 ,mr4  ,burton#cj  
found a deposit replete with existing   
species of shells1 at  the height of    
#bjj feet4 ,in an admirable series of   
drawings by ,captain  ,moresby1 ,i could
 see how continuously the cliff-bounded 
low plains of  this formation extended  
with a nearly equable height1 both on   
the  eastern and western shores4 ,the   
southern coast of ,arabia seems to have 
been subjected to the same elevatory    
movement1 for ,dr4 ,malcolmson found  at

 ,sahar low cliffs containing shells and
 corals1 apparently of recent  species4 
#bi ,rppell1 8,reise in ,abyssinien10   
,band i41 s4 #ada4       #cj ,lyell's   
8,principles of ,geology10 #eth edition1
 volume iv41 page   #be4      ,the      
,persian ,gulf abounds with coral-reefs2
 but as it is difficult to  distinguish 
them from sand-banks in this shallow    
sea1 ,i have coloured  only some near   
the mouth2 towards the head of the gulf 
,mr4  ,ainsworth#ca says that the land  
is worn into terraces1 and that the     
beds contain organic remains of existing
 forms4 ,the ,west ,indian  ,archipelago
 of 8fringed0 islands1 alone remains to 
be mentioned2  evidence of an elevation 
within a late tertiary epoch of nearly  
the  whole of this great area1 may be   
found in the works of almost all the    
naturalists who have visited it4 ,i will
 give some of the principal  references 
in a note4#cb     #ca ,ainsworth's      
8,assyria and ,babylon10 page #bag4     
#cb ,on ,florida and the north shores of

 the ,gulf of ,mexico1 ,rogers'         
8,report to ,brit4 ,assoc40 volume iii41
 page #ad4--,on the shores of   ,mexico1
 ,humboldt1 8,polit4 ,essay on ,new     
,spain10 volume i41 page #fb4 7,i   have
 also some corroborative facts with     
respect to the shores of                
,mexico47--,honduras and the ,antilles1 
,lyell's 8,principles10 #eth edition1   
volume iv41 page #bb4--,santa ,cruz and 
,barbadoes1 ,prof4 ,hovey1              
8,silliman's ,journal01 volume xxxv41   
page #gd4--,st4 ,domingo1               
,courrojolles1 8,journ de ,phys40 tom4  
liv41 page #ajf4--;,bahamas1 8,united   
,service ,journal01 ,no4 lxxi41 pages   
#bah and #bbd4 ,jamaica1 ,de la ,beche1 
8,geol4 ,man40 page #adb4--;,cuba1      
,taylor in 8,lond4 and ,edin4 ,mag40    
volume   xi41 page #ag4 ,dr4 ,daubeny   
also1 at a meeting of the ,geolog4      
,soc41   orally described some very     
modern beds lying on the ,n4,w4 parts of
   ,cuba4 ,i might have added many other
 less important references4      ,it is 

very remarkable on reviewing these      
details1 to observe in how  many        
instances fringing-reefs round the      
shores1 have coincided with the         
existence on the land of upraised       
organic remains1 which seem1 from       
evidence more or less satisfactory1 to  
belong to a late tertiary  period4 ,it  
may1 however1 be objected1 that similar 
proofs of elevation1  perhaps1 occur on 
the coasts coloured blue in our map3 but
 this  certainly is not the case with   
the few following and doubtful          
exceptions4    ,the entire area of the  
,red ,sea appears to have been upraised 
within a  modern period2 nevertheless ,i
 have been compelled 7though on         
unsatisfactory evidence1 as given in the
 ,appendix7 to class the reefs  in the  
middle part1 as barrier-reefs2 should1  
however1 the statements  prove accurate 
to the less height of the tertiary bed  
in this middle  part1 compared with the 
northern and southern districts1 we     
might well  suspect that it had subsided

 subsequently to the general elevation  
by  which the whole area has been       
upraised4 ,several authors#cc have      
stated  that they have observed shells  
and corals high up on the mountains of  
the ,society ,islands1--a group         
encircled by barrier-reefs1 and1        
therefore1 supposed to have subsided3 at
 ,tahiti ,mr4 ,stutchbury found on  the 
apex of one of the highest mountains1   
between #e1jjj and #g1jjj feet  above   
the level of the sea1 8a distinct and   
regular stratum of  semi-fossil coral40 
,at ,tahiti1 however1 other naturalists1
 as well as  myself1 have searched in   
vain at a low level near the coast1 for 
upraised shells or masses of coral-reef1
 where if present they could  hardly    
have been overlooked4 ,from this fact1  
,i concluded that probably  the organic 
remains strewed high up on the surface  
of the land1 had  originally been       
embedded in the volcanic strata1 and had
 subsequently  been washed out by the   
rain4 ,i have since heard from the ,rev4

 ,w4 ,ellis1  that the remains which he 
met with1 were 7as he believes7         
interstratified with an argillaceous    
tuff2 this likewise was the case  with  
the shells observed by the ,rev4 ,d4    
,tyerman at ,huaheine4 ,these  remains  
have not been specifically examined2    
they may1 therefore1 and  especially the
 stratum observed by ,mr4 ,stutchbury at
 an immense height1  be contemporaneous 
with the first formation of the ,society
 ,islands1 and  be of any degree of     
antiquity2 or they may have been        
deposited at some  subsequent1 but      
probably not very recent1 period of     
elevation2 for if  the period had been  
recent1 the entire surface of the coast 
land of  these islands1 where the reefs 
are so extensive1 would have been coated
  with upraised coral1 which certainly  
is not the case4 ,two of the  ,harvey1  
or ,cook ,islands1 namely1 ,aitutaki and
 ,manouai1 are encircled by  reefs1     
which extend so far from the land1 that 
,i have coloured them  blue1 although   

with much hesitation1 as the space      
within the reef is  shallow1 and the    
outline of the land is not abrupt4      
,these two islands  consist of          
coral-rock2 but ,i have no evidence of  
their recent  elevation1 besides1 the   
improbability of ,mangaia1 a fringed    
island in  the same group 7but distant  
#agj miles71 having retained its nearly 
perfect atoll-like structure1 during any
 immense lapse of time after  its       
upheaval4 ,the ,red ,sea1 therefore1 is 
the only area in which we have  clear   
proofs of the recent elevation of a     
district1 which1 by our  theory         
7although the barrier-reefs are there   
not well characterised71  has lately    
subsided4 ,but we have no reason to be  
surprised at  oscillation1 of level of  
this kind having occasionally taken     
place4  ,there can be scarcely any doubt
 that ,savage1 ,aurora1#cd and ,mangaia 
,islands1 and several of the islands in 
the ,friendly group1 existed  originally
 as atolls1 and these have undoubtedly  

since been upraised to  some height     
above the level of the sea2 so that by  
our theory1 there  has here1 also1 been 
an oscillation of level1 --elevation    
having  succeeded subsidence1 instead   
of1 as in the middle part of the ,red   
,sea  and at the ,harvey ,islands1      
subsidence having probably succeeded    
recent  elevation4     #cc ,ellis1 in   
his 8,polynesian ,researches10 was the  
first to call   attention to these      
remains 7volume i41 page #ch71 and the  
tradition of   the natives concerning   
them4 ,see also ,williams1 8,nar4 of    
,missionary   ,enterprise10 page #ba2   
also ,tyerman and ,g4 ,bennett1         
8,journal of   ,voyage10 volume i41 page
 #bac2 also ,mr4 ,couthouy's 8,remarks10
 page #ea2   but this principal fact1   
namely1 that there is a mass of upraised
   coral on the narrow peninsula of     
,tiarubu1 is from hearsay evidence2     
also ,mr4 ,stutchbury1 8,west of        
,england ,journal10 ,no4 i41 page #ed4  
,there   is a passage in ,von ,zach1    

8,corres4 ,astronom40 volume x41 page   
#bff1   inferring an uprising at        
,tahiti1 from a footpath now used1 which
 was   formerly impassable2 but ,i      
particularly inquired from several      
native   chiefs1 whether they knew of   
any change of this kind1 and they were  
unanimous in giving me an answer in the 
negative4       #cd ,aurora ,island is  
described by ,mr4 ,couthouy 78,remarks10
 page #eh72   it lies #abj miles        
north-east of ,tahiti2 it is not        
coloured in the   appended map1 because 
it does not appear to be fringed by     
living   reefs4 ,mr4 ,couthouy describes
 its summit as 8presenting a broad      
table-land which declines a few feet    
towards the centre1 where we may        
suppose the lagoon to have been placed40
 ,it is about two hundred feet   in     
height1 and consists of reef-rock and   
conglomerate1 with existing   species of
 coral embedded in it4 ,the island has  
been elevated at two   successive       
periods2 the cliffs being marked halfway

 up with a   horizontal water-worn line 
of deep excavations4 ,aurora ,island    
seems   closely to resemble in structure
 ,elizabeth ,island1 at the southern end
   of the ,low ,archipelago4      ,it is
 an interesting fact1 that ,fais1 which1
 from its composition1  form1 height1   
and situation at the western end of the 
,caroline  ,archipelago1 one is strongly
 induced to believe existed before its  
upheaval as an atoll1 lies exactly in   
the prolongation of the curved  line of 
the ,mariana group1 which we know to be 
a line of recent  elevation4 ,i may add1
 that ,elizabeth ,island1 in the        
southern part of  the ,low ,archipelago1
 which seems to have had the same kind  
of origin as  ,fais1 lies near ,pitcairn
 ,island1 the only one in this part of  
the ocean  which is high1 and at the    
same time not surrounded by an          
encircling  barrier-reef4    ,on the    
absence of active ,volcanoes in the     
areas of subsidence1 and on  their      
frequent presence in the areas of       

elevation4--,before making some         
concluding remarks on the relations of  
the spaces coloured blue and  red1 it   
will be convenient to consider the      
position on our map of the  volcanoes   
historically known to have been in      
action4 ,it is impossible  not to be    
struck1 first with the absence of       
volcanoes in the great  areas of        
subsidence tinted pale and dark         
blue1--namely1 in the central  parts of 
the ,indian ,ocean1 in the ,china ,sea1 
in the sea between the  barriers of     
,australia and ,new ,caledonia1 in the  
,caroline1 ,marshall1  ,gilbert1 and    
,low ,archipelagoes2 and1 secondly1 with
 the coincidence of  the principal      
volcanic chains with the parts coloured 
red1 which  indicates the presence of   
fringing-reefs2 and1 as we have just    
seen1  the presence in most cases of    
upraised organic remains of a modern    
date4 ,i may here remark that the reefs 
were all coloured before the  volcanoes 
were added to the map1 or indeed before 

,i knew of the  existence of several of 
them4    ,the volcano in ,torres        
,strait1 at the northern point of       
,australia1 is  that which lies nearest 
to a large subsiding area1 although     
situated  #abe miles within the outer   
margin of the actual barrier-reef4 ,the 
,great  ,comoro ,island1 which probably 
contains a volcano1 is only twenty miles
  distant from the barrier-reef of      
,mohila2 ,ambil volcano1 in the         
,philippines1 is distant only a little  
more than sixty miles from the          
atoll-formed ,appoo reef3 and there are 
two other volcanoes in the map  within  
ninety miles of circles coloured blue4  
,these few cases1 which  thus offer     
partial exceptions to the rule1 of      
volcanoes being placed  remote from the 
areas of subsidence1 lie either near    
single and  isolated atolls1 or near    
small groups of encircled islands2 and  
these  by our theory can have1 in few   
instances1 subsided to the same amount  
in depth or area1 as groups of atolls4  

,there is not one active volcano  within
 several hundred miles of an            
archipelago1 or even a small group  of  
atolls4 ,it is1 therefore1 a striking   
fact that in the ,friendly              
,archipelago1 which owes its origin to  
the elevation of a group of  atolls1 two
 volcanoes1 and1 perhaps1 others#ce are 
known to be in  action3 on the other    
hand1 on several of the encircled       
islands in the  ,pacific1 supposed by   
our theory to have subsided1 there are  
old craters  and streams of lava1 which 
show the effects of past and ancient    
eruptions4 ,in these cases1 it would    
appear as if the volcanoes had come     
into action1 and had become extinguished
 on the same spots1 according  as the   
elevating or subsiding movements        
prevailed4     #ce ,see the note at p4  
#aba1 on the authorities for colouring  
the   volcanoes in the appended map4    
,there are some other coasts on the map1
 where volcanoes in a state of  action  
concur with proofs of recent elevation1 

besides those coloured  red from being  
fringed by coral-reefs4 ,thus ,i hope to
 show in a future  volume1 that nearly  
the whole line of the west coast of     
,south ,america1  which forms the       
greatest volcanic chain in the world1   
from near the  equator for a space of   
between #b1jjj and #c1jjj miles         
southward1 has  undergone an upward     
movement during a late geological       
period4 ,the  islands on the            
north-western shores of the ,pacific1   
which form the  second greatest volcanic
 chain1 are very imperfectly known2 but 
,luzon1  in the ,philippines1 and the   
,loo ,choo ,islands1 have been recently 
elevated2 and at ,kamtschatka#cf there  
are extensive tertiary beds of  modern  
date4 ,evidence of the same nature1 but 
not very satisfactory1  may be detected 
in ,northern ,new ,zealand where there  
are two volcanoes4  ,the co-existence in
 other parts of the world of active     
volcanoes1 with  upraised beds of a     
modern tertiary origin1 will occur to   

every  geologist4#cg ,nevertheless1     
until it could be shown that volcanoes  
were inactive1 or did not exist in      
subsiding areas1 the conclusion that    
their distribution depended on the      
nature of the subterranean movements  in
 progress1 would have been hazardous4   
,but now1 viewing the appended  map1 it 
may1 ,i think1 be considered as almost  
established1 that  volcanoes are often  
7not necessarily always7 present in     
those areas  where the subterranean     
motive power has lately forced1 or is   
now  forcing outwards1 the crust of the 
earth1 but that they are invariably     
absent in those1 where the surface has  
lately subsided or is still             
subsiding4#ch     #cf ,at ,sedanka1 in  
latitude #eh ,n4 7,von ,buch's          
8,descrip4 des ,isles   ,canaries10 page
 #dee74 ,in a forthcoming part1 ,i shall
 give the evidence   referred to with   
respect to the elevation of ,new        
,zealand4       #cg ,during the         
subterranean disturbances which took    

place in ,chile1   in #ahce1 ,i have    
shown 78,geolog4 ,trans40 #bnd ,ser41   
vol4 v41 page #fjf7   that at the same  
moment that a large district was        
upraised1 volcanic   matter burst forth 
at widely separated points1 through both
 new and   old vents4       #ch ,we may 
infer from this rule1 that in any old   
deposit1 which   contains               
interstratified beds of erupted matter1 
there was at the   period1 and in the   
area of its formation1 a tendency to an 
upward   movement in the earth's        
surface1 and certainly no movement of   
subsidence4      ,on the relations of   
the areas of ,subsidence and            
,elevation4--,the  immense surfaces on  
the map1 which1 both by our theory and  
by the plain  evidence of upraised      
marine remains1 have undergone a change 
of level  either downwards or upwards   
during a late period1 is a most         
remarkable  fact4 ,the existence of     
continents shows that the areas have    
been  immense which at some period have 

been upraised2 in ,south ,america we    
may feel sure1 and on the north-western 
shores of the ,indian ,ocean we  may    
suspect1 that this rising is either now 
actually in progress1 or  has taken     
place quite recently4 ,by our theory1 we
 may conclude that the  areas are       
likewise immense which have lately      
subsided1 or1 judging from  the         
earthquakes occasionally felt and from  
other appearances1 are now  subsiding4  
,the smallness of the scale of our map  
should not be  overlooked3 each of the  
squares on it contains 7not allowing for
 the  curvature of the earth7 #haj1jjj  
square miles4 ,look at the space of     
ocean from near the southern end of the 
,low ,archipelago to the northern  end  
of the ,marshall ,archipelago1 a length 
of #d1ejj miles1 in which1 as  far as is
 known1 every island1 except ,aurora    
which lies just without  the ,low       
,archipelago1 is atoll-formed4 ,the     
eastern and western  boundaries of our  
map are continents1 and they are rising 

areas3 the  central spaces of the great 
,indian and ,pacific ,oceans1 are mostly
  subsiding2 between them1 north of     
,australia1 lies the most broken land   
on the globe1 and there the rising parts
 are surrounded and penetrated  by areas
 of subsidence1#ci so that the          
prevailing movements now in  progress1  
seem to accord with the actual states of
 surface of the great  divisions of the 
world4     #ci ,i suspect that the ,arru
 and ,timor-laut ,islands present an    
included small area of subsidence1 like 
that of the ,china ,sea1 but ,i   have  
not ventured to colour them from my     
imperfect information1 as   given in the
 ,appendix4      ,the blue spaces on the
 map are nearly all elongated2 but it   
does not  necessarily follow from this  
7a caution1 for which ,i am indebted to 
,mr4  ,lyell71 that the areas of        
subsidence were likewise elongated2 for 
the  subsidence of a long1 narrow space 
of the bed of the ocean1 including  in  
it a transverse chain of mountains1     

surmounted by atolls1 would only  be    
marked on the map by a transverse blue  
band4 ,but where a chain of  atolls and 
barrier-reefs lies in an elongated area1
 between spaces  coloured red1 which    
therefore have remained stationary or   
have been  upraised1 this must have     
resulted either from the area of        
subsidence  having originally been      
elongated 7owing to some tendency in the
 earth's  crust thus to subside71 or    
from the subsiding area having          
originally  been of an irregular figure1
 or as broad as long1 and having since  
been  narrowed by the elevation of      
neighbouring districts4 ,thus the areas1
  which subsided during the formation of
 the great north and south lines  of    
atolls in the ,indian ,ocean1--of the   
east and west line of the  ,caroline    
atolls1--and of the north-west and      
south-east line of the  barrier-reefs of
 ,new ,caledonia and ,louisiade1 must   
have originally been  elongated1 or if  
not so1 they must have since been made  

elongated by  elevations1 which we know 
to belong to a recent period4    ,i     
infer from ,mr4 ,hopkins' researches1#dj
 that for the formation of a  long chain
 of mountains1 with few lateral spurs1  
an area elongated in  the same direction
 with the chain1 must have been         
subjected to an  elevatory movement4    
,mountain-chains1 however1 when already 
formed1  although running in very       
different directions1 it seems1#da may  
be  raised together by a widely-acting  
force3 so1 perhaps1 mountain-chains  may
 subside together4 ,hence1 we cannot    
tell1 whether the ,caroline and         
,marshall ,archipelagoes1 two groups of 
atolls running in different  directions 
and meeting each other1 have been formed
 by the subsidence  of two areas1 or of 
one large area1 including two distinct  
lines of  mountains4 ,we have1 however1 
in the southern prolongation of the     
,mariana ,islands1 probable evidence of 
a line of recent elevation having       
intersected one of recent subsidence4 ,a

 view of the map will show that1        
generally1 there is a tendency to       
alternation in the parallel areas       
undergoing opposite kinds of movement2  
as if the sinking of one area  balanced 
the rising of another4     #dj          
8,researches in ,physical ,geology10    
,transact4 ,cambridge ,phil4 ,soc41     
volume vi1 part i4       #da ,for       
instance in ,s4 ,america from latitude  
#cd1 for very many   degrees southward  
there are upraised beds containing      
recent species of   shells1 on both the 
,atlantic and ,pacific side of the      
continent1 and   from the gradual ascent
 of the land1 although with very unequal
   slopes1 on both sides towards the    
,cordillera1 ,i think it can hardly be  
doubted that the entire width has been  
upraised in mass within the   recent    
period4 ,in this case the two ,w4,n4,w4 
and ,e4,s4,e4 mountain-lines1   namely  
the ,sierra ,ventana and the ,s4        
,tapalguen1 and the great north   and   
south line of the ,cordillera have been 

together raised4 ,in the   ,west ,indies
 the ,n4 and ,s4 line of the ,eastern   
,antilles1 and the ,e4 and   ,w4 line of
 ,jamaica1 appear both to have been     
upraised within the   latest geological 
period4      ,the existence in many     
parts of the world of high table-land1  
proves  that large surfaces have been   
upraised in mass to considerable heights
  above the level of the ocean2 although
 the highest points in almost  every    
country consist of upturned strata1 or  
erupted matter3 and from  the immense   
spaces scattered with atolls1 which     
indicate that land  originally existed  
there1 although not one pinnacle now    
remains above  the level of the sea1 we 
may conclude that wide areas have       
subsided to  an amount1 sufficient to   
bury not only any formerly existing     
table-land1 but even the heights formed 
by fractured strata1 and  erupted       
matter4 ,the effects produced on the    
land by the later elevatory  movements1 
namely1 successively rising cliffs1     

lines of erosion1 and  beds of literal  
shells and pebbles1 all requiring time  
for their  production1 prove that these 
movements have been very slow2 we can1  
however1 infer this with safety1 only   
with respect to the few last  hundred   
feet of rise4 ,but with reference to the
 whole vast amount of  subsidence1      
necessary to have produced the many     
atolls widely scattered  over immense   
spaces1 it has already been shown 7and  
it is1 perhaps1 the  most interesting   
conclusion in this volume71 that the    
movements must  either have been uniform
 and exceedingly slow1 or have been     
effected by  small steps1 separated from
 each other by long intervals of time1  
during which the reef-constructing      
polypifers were able to bring up  their 
solid frameworks to the surface4 ,we    
have little means of judging  whether   
many considerable oscillations of level 
have generally occurred  during the     
elevation of large tracts2 but we know1 
from clear  geological evidence1 that   

this has frequently taken place2 and we 
have  seen on our map1 that some of the 
same islands have both subsided and     
been upraised4 ,i conclude1 however1    
that most of the large blue spaces1     
have subsided without many and great    
elevatory oscillations1 because  only a 
few upraised atolls have been observed3 
the supposition that  such elevations   
have taken place1 but that the upraised 
parts have been  worn down by the surf1 
and thus have escaped observation1 is   
overruled  by the very considerable     
depth of the lagoons of all the larger  
atolls2  for this could not have been   
the case1 if they had suffered repeated 
elevations and abrasion4 ,from the      
comparative observations made in  these 
latter pages1 we may finally conclude1  
that the subterranean  changes which    
have caused some large areas to rise1   
and others to  subside1 have acted in a 
very similar manner4                    
,recapitulation4--,in the three first   
chapters1 the principal kinds of        

coral-reefs were described in detail1   
and they were found to differ  little1  
as far as relates to the actual surface 
of the reef4 ,an atoll  differs from an 
encircling barrier-reef only in the     
absence of land  within its central     
expanse2 and a barrier-reef differs from
 a  fringing-reef1 in being placed at a 
much greater distance from the land     
with reference to the probable          
inclination of its submarine foundation1
  and in the presence of a deep-water   
lagoon-like space or moat within  the   
reef4 ,in the fourth chapter the growing
 powers of the  reef-constructing       
polypifers were discussed2 and it was   
shown1 that  they cannot flourish       
beneath a very limited depth4 ,in       
accordance with  this limit1 there is no
 difficulty respecting the foundations  
on which  fringing-reefs are based2     
whereas1 with barrier-reefs and atolls1 
there  is a great apparent difficulty on
 this head2 in barrier-reefs from the   
improbability of the rock of the coast  

or of banks of sediment  extending1 in  
every instance1 so far seaward within   
the required  depth2--and in atolls1    
from the immensity of the spaces over   
which they  are interspersed1 and the   
apparent necessity for believing that   
they  are all supported on              
mountain-summits1 which although rising 
very near  to the surface-level of the  
sea1 in no one instance emerge above it4
 ,to  escape this latter most improbable
 admission1 which implies the  existence
 of submarine chains of mountains of    
almost the same height1  extending over 
areas of many thousand square miles1    
there is but one  alternative2 namely1  
the prolonged subsidence of the         
foundations1 on  which the atolls were  
primarily based1 together with the      
upward growth  of the reef-constructing 
corals4 ,on this view every difficulty  
vanishes2 fringing reefs are thus       
converted into barrier-reefs2 and       
barrier-reefs1 when encircling islands1 
are thus converted into atolls1  the    

instant the last pinnacle of land sinks 
beneath the surface of the  ocean4      
,thus the ordinary forms and certain    
peculiarities in the structure of       
atolls and barrier-reefs can be         
explained2--namely1 the wall-like       
structure on their inner sides1 the     
basin or ring-like shape both of  the   
marginal and central reefs in the       
,maldiva atolls--the union of some      
atolls as if by a ribbon--the apparent  
disseverment of others--and the         
occurrence1 in atolls as well as in     
barrier-reefs1 of portions of reef1  and
 of the whole of some reefs1 in a dead  
and submerged state1 but  retaining the 
outline of living reefs4 ,thus can be   
explained the  existence of breaches    
through barrier-reefs in front of       
valleys1 though  separated from them by 
a wide space of deep water2 thus1 also1 
the  ordinary outline of groups of      
atolls and the relative forms of the    
separate atolls one to another2 thus can
 be explained the proximity of  the two 

kinds of reefs formed during subsidence1
 and their separation  from the spaces  
where fringing-reefs abound4 ,on        
searching for other  evidence of the    
movements supposed by our theory1 we    
find marks of  change in atolls and in  
barrier-reefs1 and of subterranean      
disturbances  under them2 but from the  
nature of things1 it is scarcely        
possible to  detect any direct proofs of
 subsidence1 although some appearances  
are  strongly in favour of it4 ,on the  
fringed coasts1 however1 the presence   
of upraised marine bodies of a recent   
epoch1 plainly show1 that these  coasts1
 instead of having remained stationary1 
which is all that can be  directly      
inferred from our theory1 have generally
 been elevated4    ,finally1 when the   
two great types of structure1 namely    
barrier-reefs  and atolls on the one    
hand1 and fringing-reefs on the other1  
were laid  down in colours on our map1 a
 magnificent and harmonious picture of  
the  movements1 which the crust of the  

earth has within a late period          
undergone1 is presented to us4 ,we there
 see vast areas rising1 with  volcanic  
matter every now and then bursting forth
 through the vents or  fissures with    
which they are traversed4 ,we see other 
wide spaces slowly  sinking without any 
volcanic outburst1 and we may feel sure1
 that this  sinking must have been      
immense in amount as well as in area1   
thus to  have buried over the broad face
 of the ocean every one of those        
mountains1 above which atolls now stand 
like monuments1 marking the  place of   
their former existence4 ,reflecting how 
powerful an agent with  respect to      
denudation1 and consequently to the     
nature and thickness of  the deposits in
 accumulation1 the sea must ever be1    
when acting for  prolonged periods on   
the land1 during either its slow        
emergence or  subsidence2 reflecting1   
also1 on the final effects of these     
movements  in the interchange of land   
and ocean-water on the climate of the   

earth1  and on the distribution of      
organic beings1 ,i may be permitted to  
hope1  that the conclusions derived from
 the study of coral-formations1         
originally attempted merely to explain  
their peculiar forms1 may be  thought   
worthy of the attention of geologists4  
,,appendix4    ,,containing ,a          
,,detailed ,,description ,,of ,,the     
,,reefs ,,and ,,islands ,,in ,,plate    
,,iii4    ,in the beginning of the last 
chapter ,i stated the principles on     
which  the map is coloured4 ,there only 
remains to be said1 that it is an exact 
copy of one by ,m4 ,c4 ,gressier1       
published by the ,dpt gnral de la       
,marine1 in #ahce4 ,the names have been 
altered into ,english1 and the          
longitude has been reduced to that of   
,greenwich4 ,the colours were first     
laid down on accurate charts1 on a large
 scale4 ,the data1 on which the         
volcanoes historically known to have    
been in action1 have been marked  with  
vermillion1 were given in a note to the 

last chapter4 ,i will  commence my      
description on the eastern side of the  
map1 and will  describe each group of   
islands consecutively1 proceeding       
westward  across the ,pacific and       
,indian ,oceans1 but ending with the    
,west ,indies4    ,the ,,western        
,,shores ,,of ,,america appear to be    
entirely without  coral-reefs2 south of 
the equator the survey of the 8,beagle01
 and north  of it1 the published charts 
show that this is the case4 ,even in the
 ,bay  of ,panama1 where corals         
flourish1 there are no true coral-reefs1
 as ,i  have been informed by ,mr4      
,lloyd4 ,there are no coral-reefs in the
  ,galapagos ,archipelago1 as ,i know   
from personal inspection2 and ,i        
believe there are none on the ,cocos1   
,revilla-gigedo1 and other  neighbouring
 islands4 ,clipperton rock1 #aj ,n41    
#aji ,w41 has lately  been surveyed by  
,captain ,belcher2 in form it is like   
the crater of a  volcano4 ,from a       
drawing appended to the ,,ms4 plan in   

the ,admiralty1 it  evidently is not an 
atoll4 ,the eastern parts of the        
,pacific present an  enormous area1     
without any islands1 except ,easter1 and
 ,sala1 and  ,gomez ,islands1 which do  
not appear to be surrounded by reefs4   
,the ,,low ,,archipelago4--,this group  
consists of about eighty atolls3 it     
will be quite superfluous to refer to   
descriptions of each4 ,in  ,d',urville  
and ,lottin's chart1 one island         
7,wolchonsky7 is written with  a capital
 letter1 signifying1 as explained in a  
former chapter1 that it  is a high      
island2 but this must be a mistake1 as  
the original chart by  ,bellinghausen   
shows that it is a true atoll4 ,captain 
,beechey says of  the thirty-two groups 
which he examined 7of the greater number
 of which  ,i have seen beautiful ,,ms4 
charts in the ,admiralty71 that         
twenty-nine  now contain lagoons1 and he
 believes the other three originally    
did4  ,bellinghausen 7see an account of 
his ,russian voyage1 in the 8,biblioth4 

des ,voyages10 #ahcd1 page #ddc7 says1  
that the seventeen islands which he     
discovered resembled each other in      
structure1 and he has given charts  on a
 large scale of all of them4 ,kotzebue  
has given plans of several2  ,cook and  
,bligh mention others2 a few were seen  
during the voyage of the  8,beagle02 and
 notices of other atolls are scattered  
through several  publications4 ,the     
,acton group in this archipelago has    
lately been  discovered 78,geographical 
,journal01 volume vii41 page #ded72 it  
consists  of three small and low islets1
 one of which has a lagoon4 ,another    
lagoon-island has been discovered       
78,naut4 ,mag40 #ahci1 page #ggj71 in   
#bb  #d ,s41 and #acf #bj ,w4 ,towards  
the ,s4,e4 part of the group1 there are 
some islands of different formation3    
,elizabeth ,island is described by      
,beechey 7page #df1 #dto edition7 as    
fringed by reefs1 at the distance of    
between two and three hundred yards2    
coloured red4 ,pitcairn ,island1  in the

 immediate neighbourhood1 according to  
the same authority1 has no  reefs of any
 kind1 although numerous pieces of coral
 are thrown up on  the beach2 the sea   
close to its shore is very deep 7see    
8,zool4 of  ,beechey's ,voyage10 page   
#afd72 it is left uncoloured4 ,gambier  
,islands  7see ,plate ,i41 ,figure #h71 
are encircled by a barrier-reef2 the    
greatest  depth within is thirty-eight  
fathoms2 coloured pale blue4 ,aurora    
,island1 which lies ,n4,e4 of ,tahiti   
close to the large space coloured  dark 
blue in the map1 has been already       
described in a note 7page #ga71  on the 
authority of ,mr4 ,couthouy2 it is an   
upraised atoll1 but as it  does not     
appear to be fringed by living reefs1 it
 is left uncoloured4    ,the ,,society  
,archipelago is separated by a narrow   
space from the ,low  ,archipelago2 and  
in their parallel direction they        
manifest some  relation to each other4  
,i have already described the general   
character  of the reefs of these fine   

encircled islands4 ,in the 8,atlas of   
the  #8,coquille's' ,voyage0 there is a 
good general chart of the group1 and    
separate plans of some of the islands4  
,tahiti1 the largest island in  the     
group1 is almost surrounded1 as seen in 
,cook's chart1 by a reef  from half a   
mile to a mile and a half from the      
shore1 with from ten to  thirty fathoms 
within it4 ,some considerable submerged 
reefs lying  parallel to the shore1 with
 a broad and deep space within1 have    
lately  been discovered 78,naut4 ,mag40 
#ahcf1 page #bfd7 on the ,n4,e4 coast of
 the  island1 where none are laid down  
by ,cook4 ,at ,eimeo the reef 8which    
like a ring surrounds it1 is in some    
places one or two miles distant  from   
the shore1 in others united to the      
beach0 7,ellis1 8,polynesian            
,researches10 volume i41 page #ah1 #abmo
 edition74 ,cook found deep water       
7twenty fathoms7 in some of the harbours
 within the reef4 ,mr4 ,couthouy1       
however1 states 78,remarks10 page #de7  

that both at ,tahiti and ,eimeo1 the    
space between the barrier-reef and the  
shore1 has been almost filled  up1--8a  
nearly continuous fringing-reef         
surrounding the island1 and  varying    
from a few yards to rather more than a  
mile in width1 the  lagoons merely      
forming canals between this and the     
sea-reef10 that is  the barrier-reef4   
,tapamanoa is surrounded by a reef at a 
considerable  distance from the shore2  
from the island being small it is       
breached1 as  ,i am informed by the     
,rev4 ,w4 ,ellis1 only by a narrow and  
crooked boat  channel4 ,this is the     
lowest island in the group1 its height  
probably  not exceeding #ejj feet4 ,a   
little way north of ,tahiti1 the low    
coral-islets of ,teturoa are situated2  
from the description of them  given me  
by the ,rev4 ,j4 ,williams 7the author  
of the 8,narrative of  ,missionary      
,enterprise071 ,i should have thought   
they had formed a small  atoll1 and     
likewise from the description given by  

the ,rev4 ,d4 ,tyerman  and ,g4 ,bennett
 78,journal of ,voyage and ,travels10   
volume i41 page #ahc71  who say that ten
 low coral-islets 8are comprehended     
within one general  reef1 and separated 
from each other by interjacent lagoons20
 but as ,mr4  ,stutchbury 78,west of    
,england ,journal10 volume i41 page #ed7
 describes it  as consisting of a mere  
narrow ridge1 ,i have left it           
uncoloured4  ,maitea1 eastward of the   
group1 is classed by ,forster as a high 
encircled island2 but from the account  
given by the ,rev4 ,d4 ,tyerman and  ,g4
 ,bennett 7volume i41 page #eg7 it      
appears to be an exceedingly abrupt     
cone1 rising from the sea without any   
reef2 ,i have left it uncoloured4  ,it  
would be superfluous to describe the    
northern islands in this group1  as they
 may be well seen in the chart          
accompanying the #dto edition of        
,cook's 8,voyages10 and in the 8,atlas  
of the #8,coquille's' ,voyage40  ,maurua
 is the only one of the northern        

islands1 in which the water  within the 
reef is not deep1 being only four and a 
half fathoms2 but  the great width of   
the reef1 stretching three miles and a  
half  southward of the land 7which is   
represented in the drawing in the       
8,atlas of the #8,coquille's' ,voyage0  
as descending abruptly to the water7    
shows1 on the principle explained in the
 beginning of the last chapter1  that it
 belongs to the barrier class4 ,i may   
here mention1 from  information         
communicated to me by the ,rev4 ,w4     
,ellis1 that on the ,n4,e4  side of     
,huaheine there is a bank of sand1 about
 a quarter of a mile  wide1 extending   
parallel to the shore1 and separated    
from it by an  extensive and deep       
lagoon2 this bank of sand rests on      
coral-rock1 and  undoubtedly was        
originally a living reef4 ,north of     
,bolabola lies the  atoll of ,toubai    
7,motou-iti of the 8#8,coquille's'      
,atlas07 which is  coloured dark blue2  
the other islands1 surrounded by        

barrier-reefs1 are  pale blue2 three of 
them are represented in ,figures #c1 #d1
 and #e1 in  ,plate ,i4 ,there are three
 low coral-groups lying a little ,e4 of 
the  ,society ,archipelago1 and almost  
forming part of it1 namely              
,bellinghausen1 which is said by        
,kotzebue 78,second ,voyage10 volume    
ii41 page #bee71 to be a lagoon-island2 
,mopeha1 which1 from ,cook's            
description 78,second ,voyage10 book    
iii41 chapter i471 no doubt is an       
atoll2 and the ,scilly ,islands1 which  
are said by ,wallis 78,voyage10  chapter
 ix47 to form a group of low islets and 
shoals1 and1  therefore1 probably1 they 
compose an atoll3 the two former have   
been  coloured blue1 but not the latter4
    ,,mendana or ,,marquesas            
,group4--,these islands are entirely    
without reefs1  as may be seen in       
,krusenstern's ,atlas1 making a         
remarkable contrast  with the adjacent  
group of the ,society ,islands4 ,mr4    
,f4,d4 ,bennett has  given some account 

of this group1 in the seventh volume of 
the  8,geographical ,journal04 ,he      
informs me that all the islands have the
  same general character1 and that the  
water is very deep close to their       
shores4 ,he visited three of them1      
namely1 ,dominicana1 ,christiana1  and  
,roapoa2 their beaches are strewed with 
rounded masses of coral1  and although  
no regular reefs exist1 yet the shore is
 in many places  lined by coral-rock1 so
 that a boat grounds on this formation4 
,hence  these islands ought probably to 
come within the class of fringed        
islands and be coloured red2 but as ,i  
am determined to err on the  cautious   
side1 ,i have left them uncoloured4     
,,cook or ,,harvey and ,,austral        
,,island4--,palmerston ,island is       
minutely  described as an atoll by      
,captain ,cook during his voyage in     
#aggd2  coloured blue4 ,aitutaki was    
partially surveyed by the 8,beagle0 7see
  map accompanying 8,voyages of         
#8,adventure' and #8,beagle'072 the land

 is  hilly1 sloping gently to the beach2
 the highest point is #cfj feet2 on  the
 southern side the reef projects five   
miles from the land3 off this  point the
 8,beagle0 found no bottom with #bgj    
fathoms3 the reef is  surmounted by many
 low coral-islets4 ,although within the 
reef the water  is exceedingly shallow1 
not being more than a few feet deep1 as 
,i am  informed by the ,rev4 ,j4        
,williams1 nevertheless1 from the great 
extension of this reef into a profoundly
 deep ocean1 this island  probably      
belongs1 on the principle lately        
adverted to1 to the barrier  class1 and 
,i have coloured it pale blue2 although 
with much  hesitation4--,manouai or     
,harvey ,island4 ,the highest point is  
about  fifty feet3 the ,rev4 ,j4        
,williams informs me that the reef here1
  although it lies far from the shore1  
is less distant than at ,aitutaki1  but 
the water within the reef is rather     
deeper3 ,i have also coloured  this pale
 blue with many doubts4--,round ,mitiaro

 ,island1 as ,i am  informed by ,mr4    
,williams1 the reef is attached to the  
shore2 coloured  red4 --,mauki or       
,maouti2 the reef round this island     
7under the name of  ,parry ,island1 in  
the 8,voyage of ,h4,m4,s4 #8,blonde'10  
page #bji7 is  described as a           
coral-flat1 only fifty yards wide1 and  
two feet under  water4 ,this statement  
has been corroborated by ,mr4 ,williams1
 who calls  the reef attached2 coloured 
red4--,aitu1 or ,wateeo2 a moderately   
elevated hilly island1 like the others  
of this group4 ,the reef is  described  
in ,cook's 8,voyage10 as attached to the
 shore1 and about one  hundred yards    
wide2 coloured red4--,fenoua-iti2 ,cook 
describes this  island as very low1 not 
more than six or seven feet high 7volume
 i41  book ii41 chapter iii1 #aggg72 in 
the chart published in the              
8#8,coquille's' ,atlas10 a reef is      
engraved close to the shore3 this       
island is not mentioned in the list     
given by ,mr4 ,williams 7page #af7 in   

the 8,narrative of ,missionary          
,enterprise20 nature doubtful4 ,as it is
 so  near ,atiu1 it has been unavoidably
 coloured red4-- ,rarotonga2 ,mr4       
,williams informs me that it is a lofty 
basaltic island with an attached  reef2 
coloured red4--,there are three islands1
 ,rourouti1 ,roxburgh1  and ,hull1 of   
which ,i have not been able to obtain   
any account1 and  have left them        
uncoloured4 ,hull ,island1 in the       
,french chart1 is written  with small   
letters as being low4--,mangaia2 height 
about three hundred  feet2 8the         
surrounding reef joins the shore0       
7,williams1 8,narrative10  page #ah72   
coloured red4--,rimetara2 ,mr4 ,williams
 informs me that the  reef is rather    
close to the shore2 but1 from           
information given me by  ,mr4 ,ellis1   
the reef does not appear to be quite so 
closely attached to  it as in the       
foregoing cases3 the island is about    
three hundred feet  high 78,naut4 ,mag40
 #ahci1 page #gch72 coloured            

red4--,rurutu2 ,mr4  ,williams and ,mr4 
,ellis inform me that this island has an
 attached reef2  coloured red4 ,it is   
described by ,cook under the name of    
,oheteroa3 he  says it is not           
surrounded1 like the neighbouring       
islands by a reef2 he  must have meant a
 distant reef4--,toubouai2 in ,cook's   
chart 78,second  ,voyage10 volume ii41  
page #b7 the reef is laid down in part  
one mile1  and in part two miles from   
the shore4 ,mr4 ,ellis 78,polynes4      
,res40 volume  iii41 page #cha7 says the
 low land round the base of the island  
is very  extensive2 and this gentleman  
informs me that the water within the    
reef  appears deep2 coloured            
blue4--,raivaivai1 or ,vivitao2 ,mr4    
,williams  informs me that the reef is  
here distant3 ,mr4 ,ellis1 however1 says
 that  this is certainly not the case on
 one side of the island2 and he         
believes that the water within the reef 
is not deep2 hence ,i have left  it     
uncoloured4--,lancaster ,reef1 described

 in 8,naut4 ,mag40 #ahcc 7page  #fic71  
as an extensive crescent-formed         
coral-reef4 ,i have not coloured        
it4--,rapa1 or ,oparree2 from the       
accounts given of it by ,ellis and      
,vancouver1 there does not appear to be 
any reef4--,i4 de ,bass is an  adjoining
 island1 of which ,i cannot find any    
account4--,kemin ,island2  ,krusenstern 
seems hardly to know its position1 and  
gives no further  particulars4          
,,islands ,,between the ,low and        
,gilbert ,archipelagoes4      ,caroline 
,island 7#aj ,s41 #aej ,w47 is described
 by ,mr4 ,f4,d4 ,bennett                
78,geographical ,journal01 volume vii41 
page #bbe7 as containing a fine  lagoon2
 coloured blue4--,flint ,island 7#aa    
,s41 #aea ,w472 ,krusenstern  believes  
that it is the same with ,peregrino1    
which is described by  ,quiros          
7,burney's 8,chron4 ,hist40 volume ii41 
page #bhc7 as 8a cluster of  small      
islands connected by a reef1 and forming
 a lagoon in the middle20  coloured     

blue4--,wostock is an island a little   
more than half a mile in  diameter1 and 
apparently quite flat and low1 and was  
discovered by  ,bellinghausen2 it is    
situated a little west of ,caroline     
,island1 but it  is not placed on the   
,french charts2 ,i have not coloured it1
 although ,i  entertain little doubt    
from the chart of ,bellinghausen1 that  
it  originally contained a small        
lagoon4--,penrhyn ,island 7#i ,s41 #aeh 
,w472  a plan of it in the 8,atlas of   
the ,first ,voyage0 of ,kotzebue1 shows 
that  it is an atoll2 blue4-- ,starbuck 
,island 7#e ,s41 #aef ,w47 is described 
in ,byron's 8,voyage in the #8,blonde'0 
7page #bjf7 as formed of a flat         
coral-rock1 with no trees2 the height   
not given2 not coloured4--,malden       
,island 7#d ,s41 #aed ,w472 in the same 
voyage 7page #bje7 this island is  said 
to be of coral formation1 and no part   
above forty feet high2 ,i  have not     
ventured to colour it1 although1 from   
being of  coral-formation1 it is        

probably fringed2 in which case it      
should be  red4--,jarvis1 or ,bunker    
,island 7#j #bj ,s41 #afj ,w47 is       
described by  ,mr4 ,f4,d4 ,bennett      
78,geographical ,journal01 volume vii41 
page #bbg7 as a  narrow1 low strip of   
coral-formation2 not coloured4--,brook1 
is a small  low island between the two  
latter2 the position1 and perhaps even  
the  existence of it is doubtful2 not   
coloured4--,pescado and ,humphrey       
,islands2 ,i can find out nothing about 
these islands1 except that the  latter  
appears to be small and low2 not        
coloured4--,rearson1 or ,grand  ,duke   
,alexander's 7#aj ,s41 #afa ,w472 an    
atoll1 of which a plan is given  by     
,bellinghausen2 blue4-- ,souvoroff      
,islands 7#ac ,s41 #afc ,w472 ,admiral  
,krusenstern1 in the most obliging      
manner1 obtained for me an account of   
these islands from ,admiral ,lazareff1  
who discovered them4 ,they consist  of  
five very low islands of                
coral-formation1 two of which are       

connected  by a reef1 with deep water   
close to it4 ,they do not surround a    
lagoon1  but are so placed that a line  
drawn through them includes an oval     
space1 part of which is shallow2 these  
islets1 therefore1 probably once  7as is
 the case with some of the islands in   
the ,caroline ,archipelago7  formed a   
single atoll2 but ,i have not coloured  
them4--,danger ,island  7#aj ,s41 #aff  
,w472 described as low by ,commodore    
,byron1 and more lately  surveyed by    
,bellinghausen2 it is a small atoll with
 three islets on it2  blue4--,clarence  
,island 7#i ,s41 #agb ,w472 discovered  
in the 8,pandora0  7,g4 ,hamilton's     
8,voyage10 page #ge73 it is said1 8in   
running along the  land1 we saw several 
canoes crossing the lagoons20 as this   
island is  in the close vicinity of     
other low islands1 and as it is said1   
that the  natives make reservoirs of    
water in old cocoa-nut trees 7which     
shows  the nature of the land71 ,i have 
no doubt it is an atoll1 and have       

coloured it blue4 ,york ,island 7#h ,s41
 #agb ,w47 is described by  ,commodore  
,byron 7chapter x4 of his 8,voyage07 as 
an atoll2  blue4--,sydney ,island 7#d   
,s41 #agb ,w47 is about three miles in  
diameter1 with its interior occupied by 
a lagoon 7,captain ,tromelin1  8,annal4 
,marit40 #ahbi1 page #big72             
blue4--,phnix ,island 7#d ,s41 #aga ,w47
  is nearly circular1 low1 sandy1 not   
more than two miles in diameter1  and   
very steep outside 7,tromelin1 8,annal4 
,marit40 #ahbi1 page #big72 it  may be  
inferred that this island originally    
contained a lagoon1 but ,i  have not    
coloured it4--,new ,nantucket 7#j #ae   
,n41 #agd ,w474 ,from the  ,french chart
 it must be a low island2 ,i can find   
nothing more about it  or about ,mary   
,island2 both uncoloured4--,gardner     
,island 7#e ,s41 #agd  ,w47 from its    
position is certainly the same as ,kemin
 ,island described  7,krusenstern1 page 
#dce1 ,appen4 to ,mem41 published #ahbg7
 as having a  lagoon in its centre2     

blue4    ,,islands ,,south of the       
,sandwich ,archipelago4      ,christmas 
,island 7#b ,n41 #aeg ,w474 ,captain    
,cook1 in his 8,third  ,voyage0 7,volume
 ii41 chapter x471 has given a detailed 
account of this  atoll4 ,the breadth of 
the islets on the reef is unusually     
great1 and  the sea near it does not    
deepen so suddenly as is generally the  
case4  ,it has more lately been visited 
by ,mr4 ,f4,d4 ,bennett 78,geographical 
,journal10 volume vii41 page #bbf72 and 
he assures me that it is low and  of    
coral-formation3 ,i particularly mention
 this1 because it is engraved  with a   
capital letter1 signifying a high       
island1 in ,d',urville and  ,lottin's   
chart4 ,mr4 ,couthouy1 also1 has given  
some account of it  78,remarks10 page   
#df7 from the ,hawaiian 8,spectator02 he
 believes it has  lately undergone a    
small elevation1 but his evidence does  
not appear to  me satisfactory2 the     
deepest part of the lagoon is said to be
 only ten  feet2 nevertheless1 ,i have  

coloured it blue4--,fanning ,island 7#d 
,n41  #aeh ,w47 according to ,captain   
,tromelin 78,ann4 ,maritim40 #ahbi1 page
  #bhc71 is an atoll3 his account as    
observed by ,krusenstern1 differs from  
that given in ,fanning's 8,voyage0 7page
 #bbd71 which1 however1 is far  from    
clear2 coloured blue4-- ,washington     
,island 7#d ,n41 #aei ,w47 is  engraved 
as a low island in ,d',urville's chart1 
but is described by  ,fanning 7page     
#bbf7 as having a much greater elevation
 than ,fanning  ,island1 and hence ,i   
presume it is not an atoll2 not         
coloured4--,palmyra  ,island 7#f ,n41   
#afb ,w47 is an atoll divided into two  
parts  7,krusenstern's 8,mem4 ,suppl40  
page #ej1 also ,fanning's 8,voyage10    
page  #bcc72 blue4--,smyth's or         
,johnston's ,islands 7#ag ,n41 #agj     
,w474 ,captain  ,smyth1 ,r4,n41 has had 
the kindness to inform me that they     
consist of two  very low1 small islands1
 with a dangerous reef off the east end 
of  them4 ,captain ,smyth does not      

recollect whether these islets1 together
  with the reef1 surrounded a lagoon2   
uncoloured4    ,,sandwich               
,,archipelago4--,hawaii2 in the chart in
 ,freycinet's 8,atlas10  small portions 
of the coast are fringed by reefs2 and  
in the  accompanying 8,hydrog4 ,memoir10
 reefs are mentioned in several places1 
and the coral is said to injure the     
cables4 ,on one side of the islet of    
,kohaihai there is a bank of sand and   
coral with five feet water on it1       
running parallel to the shore1 and      
leaving a channel of about fifteen  feet
 deep within4 ,i have coloured this     
island red1 but it is very much  less   
perfectly fringed than others of the    
group4--,maui2 in ,freycinet's  chart of
 the anchorage of ,raheina1 two or three
 miles of coast are seen  to be fringed2
 and in the 8,hydrog4 ,memoir10 8banks  
of coral along  shore0 are spoken of4   
,mr4 ,f4,d4 ,bennett informs me that the
 reefs1 on an  average1 extend about a  
quarter of a mile from the beach2 the   

land is  not very steep1 and outside the
 reefs the sea does not become deep very
  suddenly2 coloured red4--,morotoi1 ,i 
presume1 is fringed3 ,freycinet  speaks 
of the breakers extending along the     
shore at a little distance  from it4    
,from the chart1 ,i believe it is       
fringed2 coloured red4--,oahu2          
,freycinet1 in his 8,hydrog4 ,memoir10  
mentions some of the reefs4 ,mr4  ,f4,d4
 ,bennett informs me that the shore is  
skirted for forty or fifty  miles in    
length4 ,there is even a harbour for    
ships formed by the reefs1  but it is at
 the mouth of a valley2 red4--,atooi1 in
 ,la ,peyrouse's  charts1 is represented
 as fringed by a reef1 in the same      
manner as ,oahu  and ,morotoi2 and this1
 as ,i have been informed by ,mr4       
,ellis1 on part at  least of the shore1 
is of coral-formation3 the reef does not
 leave a  deep channel within2          
red4--,oneehow2 ,mr4 ,ellis believes    
that this  island is also fringed by a  
coral-reef3 considering its close       

proximity  to the other islands1 ,i have
 ventured to colour it red4 ,i have in  
vain  consulted the works of ,cook1     
,vancouver1 ,la ,peyrouse1 and          
,lisiansky1 for  any satisfactory       
account of the small islands and reefs1 
which lie  scattered in a ,n4,w4 line   
prolonged from the ,sandwich group1 and 
hence  have left them uncoloured1 with  
one exception2 for ,i am indebted to    
,mr4  ,f4,d4 ,bennett for informing me  
of an atoll-formed reef1 in latitude #bh
  #bb1 longitude #agh #cj ,w41 on which 
the 8,gledstanes0 was wrecked in  #ahcg4
 ,it is apparently of large size1 and   
extends in a ,n4,w4 and ,s4,e4  line3   
very few islets have been formed on it4 
,the lagoon seems to be  shallow2 at    
least1 the deepest part which was       
surveyed was only three  fathoms4 ,mr4  
,couthouy 78,remarks10 page #ch7        
describes this island under  the name of
 ,ocean island4 ,considerable doubts    
should be entertained  regarding the    
nature of a reef of this kind1 with a   

very shallow  lagoon1 and standing far  
from any other atoll1 on account of the 
possibility of a crater or flat bank of 
rock lying at the proper depth  beneath 
the surface of the water1 thus affording
 a foundation for a  ring-formed        
coral-reef4 ,i have1 however1 thought   
myself compelled1 from  its large size  
and symmetrical outline1 to colour it   
blue4    ,,samoa or ,,navigator         
,,group4--,kotzebue1 in his 8,second    
,voyage10 contrasts  the structure of   
these islands with many others in the   
,pacific1 in not  being furnished with  
harbours for ships1 formed by distant   
coral-reefs4  ,the ,rev4 ,j4 ,williams1 
however1 informs me1 that coral-reefs do
 occur in  irregular patches on the     
shores of these islands2 but that they  
do not  form a continuous band1 as round
 ,mangaia1 and other such perfect cases 
of fringed islands4 ,from the charts    
accompanying ,la ,peyrouse's  8,voyage10
 it appears that the north shore of     
,savaii1 ,maouna1  ,orosenga1 and       

,mannua1 are fringed by reefs4 ,la      
,peyrouse1 speaking  of ,maouna 7page   
#abf71 says that the coral-reef         
surrounding its shores1  almost touches 
the beach2 and is breached in front of  
the little coves  and streams1 forming  
passages for canoes1 and probably even  
for boats4  ,further on 7page #aei71 he 
extends the same observation to all the 
islands which he visited4 ,mr4 ,williams
 in his 8,narrative10 speaks of a  reef 
going round a small island attached to  
,oyolava1 and returning  again to it3   
all these islands have been coloured    
red4--,a chart of  ,rose ,island1 at the
 extreme west end of the group1 is given
 by  ,freycinet1 from which ,i should   
have thought that it had been an atoll2 
but according to ,mr4 ,couthouy         
78,remarks10 page #dc71 it consists of a
  reef1 only a league in circuit1       
surmounted by a very few low islets2    
the lagoon is very shallow1 and is      
strewed with numerous large boulders  of
 volcanic rock4 ,this island1 therefore1

 probably consists of a bank  of rock1 a
 few feet submerged1 with the outer     
margin of its upper  surface fringed    
with reefs2 hence it cannot be properly 
classed with  atolls1 in which the      
foundations are always supposed to lie  
at a depth1  greater than that at which 
the reef-constructing polypifers can    
live2  not coloured4    ,beveridge      
,reef1 #bj ,s41 #afg ,w41 is described  
in the 8,naut4 ,mag40  7,may #ahcc1 page
 #ddb7 as ten miles long in a ,n4 and   
,s4 line1 and eight  wide2 8in the      
inside of the reef there appears deep   
water20 there is a  passage near the    
,s4,w4 corner3 this therefore seems to  
be a submerged  atoll1 and is coloured  
blue4    ,savage ,island1 #ai ,s41 #agj 
,w41 has been described by ,cook and    
,forster4 ,the younger ,forster 7volume 
ii41 page #afc7 says it is about  forty 
feet high3 he suspects that it contains 
a low plain1 which  formerly was the    
lagoon4 ,the ,rev4 ,j4 ,williams informs
 me that the reef  fringing its shores1 

resembles that round ,mangaia2 coloured 
red4    ,,friendly ,,archipelago4       
,pylstaart ,island4 ,judging from the   
chart in  ,freycinet's 8,atlas10 ,i     
should have supposed that it had been   
regularly  fringed2 but as nothing is   
said in the 8,hydrog4 ,memoir0 7or in   
the  8,voyage0 of ,tasman1 the          
discoverer7 about coral-reefs1 ,i have  
left it  uncoloured4--,tongatabou3 ,in  
the 8,atlas of the ,voyage of the       
#8,astrolabe'10 the whole south side of 
the island is represented as  narrowly  
fringed by the same reef which forms an 
extensive platform on  the northern     
side4 ,the origin of this latter reef1  
which might have  been mistaken for a   
barrier-reef1 has already been attempted
 to be  explained1 when giving the      
proofs of the recent elevation of this  
island4-- ,in ,cook's charts the little 
outlying island also of ,eoaigee1  is   
represented as fringed2 coloured        
red4--,eoua4 ,i cannot make out from    
,captain ,cook's charts and             

descriptions1 that this island has any  
reef1  although the bottom of the       
neighbouring sea seems to be corally1   
and  the island itself is formed of     
coral-rock4 ,forster1 however1          
distinctly  78,observations10 page #ad7 
classes it with high islands having     
reefs1  but it certainly is not         
encircled by a barrier-reef and the     
younger  ,forster 78,voyage10 volume i41
 page #dbf7 says1 that 8a bed of        
coral-rocks surrounded the coast towards
 the landing-place40 ,i have  therefore 
classed it with the fringed islands and 
coloured it red4 ,the  several islands  
lying ,n4,w4 of ,tongatabou1 namely     
,anamouka1 ,komango1  ,kotou1 ,lefouga1 
,foa1 c41 are seen in ,captain ,cook's  
chart to be  fringed by reefs1 in       
several of them are connected together4 
,from the  various statements in the    
first volume of ,cook's 8,third         
,voyage10 and  especially in the fourth 
and sixth chapters1 it appears that     
these  reefs are of coral-formation1 and

 certainly do not belong to the  barrier
 class2 coloured red4--,toufoua  ,kao1  
forming the western  part of the group1 
according to ,forster have no reefs2 the
 former is an  active volcano4--,vavao4 
,there is a chart of this singularly    
formed  island1 by ,espinoza3 according 
to ,mr4 ,williams it consists of        
coral-rock3 the ,chevalier ,dillon      
informs me that it is not fringed2 not  
coloured4 ,nor are the islands of ,latte
 and ,amargura1 for ,i have not  seen   
plans on a large scale of them1 and do  
not know whether they are  fringed4     
,niouha1 #af ,s41 #agd ,w41 or ,keppel  
,island of ,wallis1 or ,cocos  ,island4 
,from a view and chart of this island   
given in ,wallis's 8,voyage0  7#dto     
edition7 it is evidently encircled by a 
reef2 coloured blue3 it is  however     
remarkable that ,boscawen ,island1      
immediately adjoining1 has  no reef of  
any kind2 uncoloured4    ,wallis        
,island1 #ac ,s41 #agf ,w41 a chart and 
view of this island in  ,wallis's       

8,voyage0 7#dto edition7 shows that it  
is encircled4 ,a view of  it in the     
8,naut4 ,mag40 ,july #ahcc1 page #cgf1  
shows the same fact2 blue4              
,alloufatou1 or ,horn ,island1 ,onouafu1
 or ,proby ,island1 and  ,hunter        
,islands1 lie between the ,navigator and
 ,fidji groups4 ,i can  find no distinct
 accounts of them4    ,,fidji or ,,viti 
,,group4--,the best chart of the        
numerous islands of this  group1 will be
 found in the 8,atlas of the            
#8,astrolabe's' ,voyage40 ,from  this1  
and from the description given in the   
8,hydrog4 ,memoir10  accompanying it1 it
 appears that many of these islands are 
bold and  mountainous1 rising to the    
height of between #c1jjj and #d1jjj     
feet4 ,most  of the islands are         
surrounded by reefs1 lying far from the 
land1 and  outside of which the ocean   
appears very deep4 ,the 8,astrolabe0    
sounded  with ninety fathoms in several 
places about a mile from the reefs1 and 
found no bottom4 ,although the depth    

within the reef is not laid down1  it is
 evident from several expressions1 that 
,captain ,d',urville believes  that     
ships could anchor within1 if passages  
existed through the outer  barriers4    
,the ,chevallier ,dillon informs me that
 this is the case3 hence  ,i have       
coloured this group blue4 ,in the ,s4,e4
 part lies ,batoa1 or  ,turtle ,island  
of ,cook 78,second ,voyage10 volume ii41
 page #bc1 and  chart1 #dto edition7    
surrounded by a coral-reef1 8which in   
some places  extends two miles from the 
shore20 within the reef the water       
appears to  be deep1 and outside it is  
unfathomable2 coloured pale blue4 ,at   
the  distance of a few miles1 ,captain  
,cook 7,ibid41 page #bd7 found a        
circular  coral-reef1 four or five      
leagues in circuit1 with deep water     
within2  8in short1 the bank wants only 
a few little islets to make it exactly  
like one of the half-drowned isles so   
often mentioned10--namely1 atolls4      
,south of ,batoa1 lies the high island  

of ,ono1 which appears in               
,bellinghausen's 8,atlas0 to be         
encircled2 as do some other small       
islands  to the south2 coloured pale    
blue2 near ,ono1 there is an annular    
reef1  quite similar to the one just    
described in the words of ,captain      
,cook2  coloured dark blue4             
,rotoumah1 #ac ,s41 #agi ,e4--,from the 
chart in ,duperrey's 8,atlas10 ,i       
thought this island was encircled1 and  
had coloured it blue1 but the           
,chevallier ,dillon assures me that the 
reef is only a shore or fringing  one2  
red4    ,independence ,island1 #aj ,s41 
#agi ,e41 is described by ,mr4 ,g4      
,bennett1  78,united ,service ,journal10
 #ahca1 part ii41 page #aig7 as a low   
island of  coral-formation1 it is small1
 and does not appear to contain a       
lagoon1  although an opening through the
 reef is referred to4 ,a lagoon probably
  once existed1 and has since been      
filled up2 left uncoloured4    ,,ellice 
,,group4--,oscar1 ,peyster1 and ,ellice 

,islands are figured in  ,arrowsmith's  
8,chart of the ,pacific0 7corrected to  
#ahcb7 as atolls1 and  are said to be   
very low2 blue4--,nederlandisch ,island4
 ,i am greatly  indebted to the kindness
 of ,admiral ,krusenstern1 for sending  
me the  original documents concerning   
this island4 ,from the plans given by   
,captains ,eeg and ,khremtshenko1 and   
from the detailed account given by  the 
former1 it appears that it is a narrow  
coral-island1 about two  miles long1    
containing a small lagoon4 ,the sea is  
very deep close to  the shore1 which is 
fronted by sharp coral-rocks4 ,captain  
,eeg compares  the lagoon with that of  
other coral-islands2 and he distinctly  
says1  the land is 8very low40 ,i have  
therefore coloured it blue4 ,admiral    
,krusenstern 78,memoir on the ,pacific10
 ,append41 #ahce7 states that its       
shores are eighty feet high2 this       
probably arose from the height of the   
cocoa-nut trees1 with which it is       
covered1 being mistaken for land4       

--,gran ,cocal is said in ,krusenstern's
 8,memoir10 to be low1 and to be        
surrounded by a reef2 it is small1 and  
therefore probably once  contained a    
lagoon2 uncoloured4--,st4 ,augustin4    
,from a chart and view  of it1 given in 
the 8,atlas of the #8,coquille's'       
,voyage10 it appears to  be a small     
atoll1 with its lagoon partly filled up2
 coloured blue4    ,,gilbert            
,,group4--,the chart of this group1     
given in the 8,atlas of the             
#8,coquille's' ,voyage10 at once shows  
that it is composed of ten well         
characterised atolls4 ,in ,d',urville   
and ,lottin's chart1 ,sydenham is       
written with a capital letter1          
signifying that it is high2 but this    
certainly is not the case1 for it is a  
perfectly characterised atoll1  and a   
sketch1 showing how low it is1 is given 
in the 8#8,coquille's'  ,atlas40 ,some  
narrow strip-like reefs project from the
 southern side of  ,drummond atoll1 and 
render it irregular4 ,the southern      

island of the  group is called ,chase   
7in some charts1 ,rotches72 of this ,i  
can find  no account1 but ,mr4 ,f4,d4   
,bennett discovered 78,geographical     
,journal01  volume vii41 page #bbi71 a  
low extensive island in nearly the same 
latitude1 about three degrees westward  
of the longitude assigned to  ,rotches1 
but very probably it is the same island4
 ,mr4 ,bennett informs  me that the man 
at the masthead reported an appearance  
of lagoon-water  in the centre2 and1    
therefore1 considering its position1 ,i 
have  coloured it blue4 --,pitt ,island1
 at the extreme northern point of the   
group1 is left uncoloured1 as its exact 
position and nature is not              
known4--,byron ,island1 which lies a    
little to the eastward1 does not  appear
 to have been visited since ,commodore  
,byron's voyage1 and it was  then seen  
only from a distance of eighteen miles2 
it is said to be low2  uncoloured4      
,ocean1 ,pleasant1 and ,atlantic        
,islands all lie considerably to the    

west of the ,gilbert group3 ,i have been
 unable to find any distinct  account of
 them4 ,ocean ,island is written with   
small letters in the  ,french chart1 but
 in ,krusenstern's 8,memoir0 it is said 
to be high4    ,,marshall ,,group4--,we 
are well acquainted with this group from
 the  excellent charts of the separate  
islands1 made during the two voyages  of
 ,kotzebue3 a reduced one of the whole  
group may be easily seen in             
,krusenstern's 8,atlas10 and in         
,kotzebue's 8,second ,voyage40 ,the     
group  consists 7with the exception of  
two little islands which probably  have 
had their lagoon filled up7 of a double 
row of twenty-three large  and          
well-characterised atolls1 from the     
examination of which ,chamisso  has     
given us his well-known account of      
coral-formations4 ,i include            
,gaspar-,rico1 or ,cornwallis ,island in
 this group1 which is described  by     
,chamisso 7,kotzebue's 8,first ,voyage10
 volume iii41 page #agi7 8as a  low     

sickle-formed group1 with mould only on 
the windward side40 ,gaspard  ,island is
 considered by some geographers as a    
distinct island lying  ,n4,e4 of the    
group1 but it is not entered in the     
chart by ,krusenstern2  left uncoloured4
 ,in the ,s4,w4 part of this group lies 
,baring ,island1  of which little is    
known 7see ,krusenstern's 8,appendix10  
#ahce1 page  #adi74 ,i have left it     
uncoloured2 but ,boston ,island ,i have 
coloured  blue1 as it is described      
7,ibid47 as consisting of fourteen small
  islands1 which1 no doubt1 enclose a   
lagoon1 as represented in a chart  in   
the 8#8,coquille's' ,atlas40--,two      
islands1 ,aur ,kawen and ,gaspar  ,rico1
 are written in the ,french chart with  
capital letters2 but this  is an error1 
for from the account given by ,chamisso 
in ,kotzebue's  8,first ,voyage10 they  
are certainly low4 ,the nature1         
position1 and even  existence1 of the   
shoals and small islands north of the   
,marshall group1  are doubtful4    ,,new

 ,,hebrides4--,any chart1 on even a     
small scale1 of these islands1 will     
show that their shores are almost       
without reefs1 presenting a  remarkable 
contrast with those of ,new ,caledonia  
on the one hand1 and  the ,fidji group  
on the other4 ,nevertheless1 ,i have    
been assured by ,mr4  ,g4 ,bennett1 that
 coral grows vigorously on their shores2
 as indeed1  will be further shown in   
some of the following notices4 ,as1     
therefore1  these islands are not       
encircled1 and as coral grows vigorously
 on their  shores1 we might almost      
conclude1 without further evidence1 that
 they  were fringed1 and hence ,i have  
applied the red colour with rather      
greater freedom than in other           
instances4--,matthew's ,rock1 an active 
volcano1 some way south of the group 7of
 which a plan is given in the  8,atlas  
of the #8,astrolabe's' ,voyage07 does   
not appear to have reefs of  any kind   
about it4--,annatom1 the southernmost of
 the ,hebrides2 from a  rough woodcut   

given in the 8,united ,service ,journal0
 7#ahca1 part iii41  page #aij71        
accompanying a paper by ,mr4 ,bennett1  
it appears that the  shore is fringed2  
coloured red4--,tanna4 ,forster1 in his 
8,observations0  7page #bb71 says ,tanna
 has on its shores coral-rock and       
madrepores2 and  the younger ,forster1  
in his account 7volume ii41 page #bfi7  
speaking of  the harbour says1 the whole
 ,s4,e4 side consists of coral-reefs1   
which  are overflowed at high-water2    
part of the southern shore in ,cook's   
chart is represented as fringed2        
coloured red4--,immer is described      
78,united ,service ,journal10 #ahca1    
part iii41 page #aib7 by ,mr4 ,bennett  
as  being of moderate elevation1 with   
cliffs appearing like sandstone3  coral 
grows in patches on its shore1 but ,i   
have not coloured it2 and ,i  mention   
these facts1 because ,immer might have  
been thought from  ,forster's           
classification 78,observations10 page   
#ad71 to have been a low  island or even

 an atoll4-- ,erromango ,island2 ,cook  
78,second ,voyage10  volume ii41 page   
#de1 #dto edition7 speaks of rocks      
everywhere lining  the coast1 and the   
natives offered to haul his boat over   
the breakers  to the sandy beach3 ,mr4  
,bennett1 in a letter to the ,editor of 
the  8,singapore ,chron410 alludes to   
the reefs on its shores4 ,it may1 ,i    
think1 be safely inferred from these    
passages that the shore is fringed  in  
parts by coral-reefs2 coloured          
red4--,sandwich ,island4 ,the east      
coast is said 7,cook's 8,second         
,voyage10 volume ii41 page #da7 to be   
low1  and to be guarded by a chain of   
breakers4 ,in the accompanying chart it 
is seen to be fringed by a reef2        
coloured red4--,mallicollo2 ,forster    
speaks of the reef-bounded shore3 the   
reef is about thirty yards wide1  and so
 shallow that a boat cannot pass over   
it4 ,forster also  78,observations10    
page #bc7 says1 that the rocks of the   
sea-shore consist  of madrepore4 ,in the

 plan of ,sandwich harbour1 the         
headlands are  represented as fringed2  
coloured red4--,aurora and ,pentecost   
,islands1  according to ,bougainville1  
apparently have no reefs2 nor has the   
large  island of ,s4 ,espiritu1 nor     
,bligh ,island or ,banks' ,islands1     
which  latter lie to the ,n4,e4 of the  
,hebrides4 ,but in none of these cases1 
have ,i met with any detailed account of
 their shores1 or seen plans on  a large
 scale2 and it will be evident1 that a  
fringing-reef of only  thirty or even a 
few hundred yards in width1 is of so    
little importance  to navigation1 that  
it will seldom be noticed1 excepting by 
chance2 and  hence ,i do not doubt that 
several of these islands1 now left      
uncoloured1 ought to be red4            
,,santa-,,cruz ,,group4--,vanikoro      
7,figure #a1 ,plate ,i47 offers a       
striking  example of a barrier-reef3 it 
was first described by the ,chevalier   
,dillon1 in his voyage1 and was surveyed
 in the 8,astrolabe02 coloured  pale    

blue4--,tikopia and ,fataka ,islands    
appear1 from the descriptions  of       
,dillon and ,d',urville1 to have no     
reefs2 ,anouda is a low1 flat  island1  
surrounded by cliffs 78#8,astrolabe'    
,hydrog40 and ,krusenstern1  8,mem40    
volume ii41 page #dcb72 these are       
uncoloured4 ,toupoua  7,otooboa of      
,dillon7 is stated by ,captain ,tromelin
 78,annales ,marit40  #ahbi1 page #bhi7 
to be almost entirely included in a     
reef1 lying at the  distance of two     
miles from the shore4 ,there is a space 
of three miles  without any reef1 which1
 although indented with bays1 offers no 
anchorage from the extreme depth of the 
water close to the shore3  ,captain     
,dillon also speaks of the reefs        
fronting this island2 coloured  blue4-- 
,santa-,cruz4 ,i have carefully examined
 the works of ,carteret1                
,d',entrecasteaux1 ,wilson1 and         
,tromelin1 and ,i cannot discover any   
mention of reefs on its shores2 left    
uncoloured4--,tinakoro is a  constantly 

active volcano without reefs4--,mendana 
,isles 7mentioned by  ,dillon under the 
name of ,mammee1 etc472 said by         
,krusenstern to be  low1 and intertwined
 with reefs4 ,i do not believe they     
include a  lagoon2 ,i have left them    
uncoloured4--,duff's ,islands compose a 
small  group directed in a ,n4,w4 and   
,s4,e4 band2 they are described by      
,wilson  7page #bif1 8,miss4 ,voy40 #dto
 edition71 as formed by bold-peaked     
land1  with the islands surrounded by   
coral-reefs1 extending about half a mile
  from the shore2 at a distance of a    
mile from the reefs he found only  seven
 fathoms4 ,as ,i have no reason for     
supposing there is deep water  within   
these reefs1 ,i have coloured them red4 
,kennedy ,island1 ,n4,e4 of  ,duff's4 ,i
 have been unable to find any account of
 it4    ,,new ,,caledonia4--,the great  
barrier-reefs on the shores of this     
island  have already been described     
7,figure #e1 ,plate ,,ii474 ,they have  
been  visited by ,labillardire1 ,cook1  

and the northern point by ,d',urville2  
this latter part so closely resembles an
 atoll that ,i have coloured it  dark   
blue4 ,the ,loyalty group is situated   
eastward of this island2  from the chart
 and description given in the 8,voyage  
of the  #8,astrolabe'10 they do not     
appear to have any reefs2 north of this 
group1 there are some extensive low     
reefs 7called ,astrolabe and  ,beaupr17 
which do not seem to be atoll-formed2   
these are left  uncoloured4             
,,australian ,,barrier-,,reef4--,the    
limits of this great reef1 which has    
already been described1 have been       
coloured from the charts of ,flinders   
and ,king4 ,in the northern parts1 an   
atoll-formed reef1 lying outside  the   
barrier1 has been described by ,bligh1  
and is coloured dark blue4 ,in  the     
space between ,australia and ,new       
,caledonia1 called by ,flinders the     
,corallian ,sea1 there are numerous     
reefs4 ,of these1 some are represented  
in ,krusenstern's 8,atlas0 as having an 

atoll-like structure2 namely1  ,bampton 
shoal1 ,frederic1 ,vine or ,horse-shoe1 
and ,alert reefs2  these have been      
coloured dark blue4    ,,louisiade3 the 
dangerous reefs which front and surround
 the western1  southern1 and northern   
coasts of this so-called peninsula and  
archipelago1 seem evidently to belong to
 the barrier class4 ,the land is  lofty1
 with a low fringe on the coast2 the    
reefs are distant1 and the  sea outside 
them profoundly deep4 ,nearly all that  
is known of this  group is derived from 
the labours of ,d',entrecasteaux and    
,bougainville3  the latter has          
represented one continuous reef ninety  
miles long1  parallel to the shore1 and 
in places as much as ten miles from it2 
coloured pale blue4 ,a little distance  
northward we have the ,laughlan         
,islands1 the reefs round which are     
engraved in the 8,atlas of the ,voyage  
of the #8,astrolabe'10 in the same      
manner as in the encircled islands of   
the ,caroline ,archipelago1 the reef is1

 in parts1 a mile and a half from  the  
shore1 to which it does not appear to be
 attached2 coloured blue4  ,at some     
little distance from the extremity of   
the ,louisiade lies the  ,wells reef1   
described in ,g4 ,hamilton's 8,voyage in
 ,h4,m4,s4 #8,pandora'0  7page #ajj73 it
 is said1 8,we found we had got embayed 
in a double reef1  which will soon be an
 island40 ,as this statement is only    
intelligible  on the supposition of the 
reef being crescent or horse-shoe       
formed1  like so many other submerged   
annular reefs1 ,i have ventured to      
colour  it blue4    ,,salomon           
,,archipelago3 the chart in             
,krusenstern's 8,atlas0 shows that      
these islands are not encircled1 and as 
coral appears from the works of         
,surville1 ,bougainville1 and           
,labillardire1 to grow on their shores1 
this circumstance1 as in the case of the
 ,new ,hebrides1 is a presumption  that 
they are fringed4 ,i cannot find out    
anything from  ,d',entrecasteaux's      

8,voyage10 regarding the southern       
islands of the  group1 so have left them
 uncoloured4--,malayta ,island in a     
rough ,,ms4  chart in the ,admiralty has
 its northern shore fringed4--,ysabel   
,island1  the ,n4,e4 part of this       
island1 in the same chart1 is also      
fringed3  ,mendana1 speaking 7,burney1  
volume i41 page #bhj7 of an islet       
adjoining  the northern coast1 says it  
is surrounded by reefs2 the shores1 also
 of  ,port ,praslin appear regularly    
fringed4--,choiseul ,island4 ,in        
,bougainville's 8,chart of ,choiseul    
,bay10 parts of the shores are fringed  
by coral-reefs4-- ,bougainville ,island4
 ,according to ,d',entrecasteaux  the   
western shore abounds with coral-reefs1 
and the smaller islands are  said to be 
attached to the larger ones by reefs2   
all the  before-mentioned islands have  
been coloured red4--,bouka ,islands4    
,captain ,duperrey has kindly informed  
me in a letter that he passed  close    
round the northern side of this island  

7of which a plan is given  in his       
8,atlas of the #8,coquille's' ,voyage071
 and that it was 8garnie  d'une bande de
 rcifs  fleur d'eau adherentes au       
rivage20 and he  infers1 from the       
abundance of coral on the islands north 
and south of  ,bouka1 that the reef     
probably is of coral2 coloured red4     
,off the north coast of the ,solomon    
,archipelago there are several small    
groups which are little known2 they     
appear to be low1 and of                
coral-formation2 and some of them       
probably have an atoll-like  structure2 
the ,chevallier ,dillon1 however1       
informs me that this is not  the case   
with the ,b4 de ,candelaria4--,outong   
,java1 according to the  ,spanish       
navigator1 ,maurelle1 is thus           
characterised2 but this is the  only one
 which ,i have ventured to colour blue4 
,,new ,,ireland4--,the shores of the    
,s4,w4 point of this island and some    
adjoining islets1 are fringed by reefs1 
as may be seen in the 8,atlases  of the 

,voyages of the #8,coquille' and        
#8,astrolabe'40 ,m4 ,lesson observes    
that the reefs are open in front of each
 streamlet4 ,the ,duke of  ,york's      
,island is also fringed2 but with regard
 to the other parts of  ,new ,ireland1  
,new ,hanover1 and the small islands    
lying northward1 ,i  have been unable to
 obtain any information4 ,i will only   
add that no  part of ,new ,ireland      
appears to be fronted by distant reefs4 
,i have  coloured red only the above    
specified portions4    ,,new ,,britain  
and the ,,northern ,,shore of ,,new     
,,guinea4--,from the charts in  the     
8,voyage of the #8,astrolabe'10 and from
 the 8,hydrog4 ,memoir10 it  appears    
that these coasts are entirely without  
reefs1 as are the  ,schouten ,islands1  
lying close to the northern shore of    
,new ,guinea4  ,the western and         
south-western parts of ,new ,guinea1    
will be treated of  when we come to the 
islands of the ,east ,indian            
,archipelago4    ,,admiralty            

,,group4--,from the accounts by         
,bougainville1 ,maurelle1               
,d',entrecasteaux1 and the scattered    
notices collected by ,horsburgh1 it     
appears1 that some of the many islands  
composing it1 are high1 with a  bold    
outline2 and others are very low1 small 
and interlaced with reefs4  ,all the    
high islands appear to be fronted by    
distant reefs rising  abruptly from the 
sea1 and within some of which there is  
reason to  believe that the water is    
deep4 ,i have therefore little doubt    
they are  of the barrier class4--,in the
 southern part of the group we have     
,elizabeth ,island1 which is surrounded 
by a reef at the distance of a  mile2   
and two miles eastward of it            
7,krusenstern1 8,append40 #ahce1 page   
#db7 there is a little island containing
 a lagoon4--,near here1 also lies       
,circular-reef 7,horsburgh1 8,direct40  
volume i41 page #fia1 #dth  edition71   
8three or four miles in diameter having 
deep water inside  with an opening at   

the ,n4,n4,w4 part1 and on the outside  
steep to40 ,i  have from these data1    
coloured the group pale blue1 and       
circular-reef  dark blue4--the          
,anachorites1 ,echequier1 and ,hermites1
 consist of  innumerable low islands of 
coral-formation1 which probably have    
atoll-like forms2 but not being able to 
ascertain this1 ,i have not  coloured   
them1 nor ,durour ,island1 which is     
described by ,carteret as  low4    ,the 
,,caroline ,,archipelago is now         
well-known1 chiefly from the            
hydrographical labours of ,lutk2 it     
contains about forty groups of  atolls1 
and three encircled islands1 two of     
which are engraved in  ,figures #b and  
#g1 ,plate ,i4 ,commencing with the     
eastern part2 the  encircling reef round
 ,ualen appears to be only about half a 
mile from  the shore2 but as the land is
 low and covered with mangroves         
78,voyage  autour du ,monde10 par ,f4   
,lutk1 volume i41 page #cci71 the real  
margin  has not probably been           

ascertained4 ,the extreme depth in one  
of the  harbours within the reef is     
thirty-three fathoms 7see charts in     
8,atlas  of #8,coquille's' ,voyage071   
and outside at half a mile distant from 
the  reef1 no bottom was obtained with  
two hundred and fifty fathoms4 ,the     
reef is surmounted by many islets1 and  
the lagoon-like channel within  is      
mostly shallow1 and appears to have been
 much encroached on by the  low land    
surrounding the central mountains2 these
 facts show that time  has allowed much 
detritus to accumulate2 coloured pale   
blue4--  ,pouynipte1 or ,seniavine4 ,in 
the greater part of the circumference   
of this island1 the reef is about one   
mile and three quarters distant2  on the
 north side it is five miles off the    
included high islets4 ,the  reef is     
broken in several places2 and just      
within it1 the depth in one  place is   
thirty fathoms1 and in another1         
twenty-eight1 beyond which1 to  all     
appearance1 there was 8un porte vaste et

 sur0 7,lutk1 volume ii41  page #d72    
coloured pale blue4--,hogoleu or ,roug4 
,this wonderful group  contains at least
 sixty-two islands1 and its reef is one 
hundred and  thirty-five miles in       
circuit4 ,of the islands1 only a few1   
about six or  eight 7see 8,hydrog4      
,descrip40 page #dbh1 of the 8,voyage of
 the  #8,astrolabe'10 and the large     
accompanying chart taken chiefly from   
that  given by ,duperrey7 are high1 and 
the rest are all small1 low1 and  formed
 on the reef4 ,the depth of the great   
interior lake has not been  ascertained2
 but ,captain ,d',urville appears to    
have entertained no doubt  about the    
possibility of taking in a frigate4 ,the
 reef lies no less  than fourteen miles 
distant from the northern coasts of the 
interior  high islands1 seven from their
 western sides1 and twenty from the     
southern2 the sea is deep outside4 ,this
 island is a likeness on a grand  scale 
to the ,gambier group in the ,low       
,archipelago4 ,of the groups of  low#a  

islands forming the chief part of the   
,caroline ,archipelago1 all  those of   
larger size1 have the true              
atoll-structure 7as may be seen in  the 
8,atlas0 by ,captain ,lutk71 and some   
even of the very small ones1 as         
,macaskill and ,duperrey1 of which plans
 are given in the 8,atlas of  the       
#8,coquille's' ,voyage40 ,there are1    
however1 some low small islands of      
coral-formation1 namely ,ollap1         
,tamatam1 ,bigali1 ,satahoual1  which do
 not contain lagoons2 but it is probable
 that lagoons  originally existed1 but  
have since filled up3 ,lutk 7volume ii41
 page  #cjd7 seems to have thought that 
all the low islands1 with only one      
exception1 contained lagoons4 ,from the 
sketches1 and from the manner in  which 
the margins of these islands are        
engraved in the 8,atlas of the  ,voyage 
of the #8,coquille'10 it might have been
 thought that they were  not low2 but by
 a comparison with the remarks of ,lutk 
7volume ii41  page #ajg1 regarding      

,bigali7 and of ,freycinet 78,hydrog4   
,memoir  #8,l',uranie' ,voyage10 page   
#ahh1 regarding ,tamatam1 ,ollap1 etc471
 it will  be seen that the artist must  
have represented the land incorrectly4  
,the  most southern island in the group1
 namely ,piguiram1 is not coloured1     
because ,i have found no account of it4 
,nougouor1 or ,monte ,verdison1  which  
was not visited by ,lutk1 is described  
and figured by ,mr4 ,bennett  78,united 
,service ,journal10 ,january #ahcb7 as  
an atoll4 ,all the  above-mentioned     
islands have been coloured blue4     #a 
,in ,d',urville and ,lottin's chart1    
,peserare is written with capital       
letters2 but this evidently is an error1
 for it is one of the low   islets on   
the reef of ,namonouyto 7see ,lutk's    
charts7--a regular atoll4      ,,western
 ,,part ,,of ,,the ,,caroline           
,,archipelago4--,fais ,island is ninety 
feet  high1 and is surrounded1 as ,i    
have been informed by ,admiral ,lutk1 by
 a  narrow reef of living coral1 of     

which the broadest part1 as represented 
in the charts1 is only #aej yards2      
coloured red4-- ,philip ,island41 ,i    
believe1 is low2 but ,hunter1 in his    
8,historical ,journal10 gives no  clear 
account of it2 uncoloured4--,elivi2 from
 the manner in which the  islets on the 
reefs are engraved1 in the 8,atlas of   
the #8,astrolabe's'  ,voyage10 ,i should
 have thought they were above the       
ordinary height1 but  ,admiral ,lutk    
assures me this is not the case3 they   
form a regular  atoll2 coloured         
blue4--,gouap 7,eap of ,chamisso71 is a 
high island  with a reef 7see chart in  
8,voyage of the #8,astrolabe'071 more   
than a  mile distant in most parts from 
the shore1 and two miles in one part4   
,captain ,d',urville thinks that there  
would be anchorage 78,hydrog4           
,descript4 #8,astrolabe' ,voyage10 page 
#dcf7 for ships within the reef1 if  a  
passage could be found2 coloured pale   
blue4--,goulou1 from the chart  in the  
8#8,astrolabe's' ,atlas10 appears to be 

an atoll4 ,d',urville  78,hydrog4       
,descript40 page #dcg7 speaks of the low
 islets on the reef2  coloured dark     
blue4    ,,pelew                        
,,islands4--,krusenstern speaks of some 
of the islands being  mountainous2 the  
reefs are distant from the shore1 and   
there are spaces  within them1 and not  
opposite valleys1 with from ten to      
fifteen  fathoms4 ,according to a ,,ms4 
chart of the group by ,lieutenant ,elmer
 in  the ,admiralty1 there is a large   
space within the reef with deepish      
water2 although the high land does not  
hold a central position with  respect to
 the reefs1 as is generally the case1 ,i
 have little doubt  that the reefs of   
the ,pelew ,islands ought to be ranked  
with the barrier  class1 and ,i have    
coloured them pale blue4 ,in ,lieutenant
 ,elmer's chart  there is a             
horseshoe-formed shoal1 laid down       
thirteen miles ,n4,w4 of  ,pelew1 with  
fifteen fathoms within the reef1 and    
some dry banks on it2  coloured dark    

blue4--,spanish1 ,martires1 ,sanserot1  
,pulo ,anna and  ,mariere ,islands are  
not coloured1 because ,i know nothing   
about them1  excepting that according to
 ,krusenstern1 the second1 third1 and   
fourth  mentioned1 are low1 placed on   
coral-reefs1 and therefore1 perhaps1    
contain lagoons2 but ,pulo ,mariere is a
 little higher4    ,,mariana            
,,archipelago1 or ,,ladrones4--,guahan4 
,almost the whole of this  island is    
fringed by reefs1 which extend in most  
parts about a third of  a mile from the 
land4 ,even where the reefs are most    
extensive1 the  water within them is    
shallow4 ,in several parts there is a   
navigable  channel for boats and canoes 
within the reefs4 ,in ,freycinet's      
8,hydrog4  ,mem40 there is an account of
 these reefs1 and in the 8,atlas10 a map
 on  a large scale2 coloured            
red4--,rota4 8,l'ile est presque        
entirement  entoure des rcifs0 7page    
#bab1 ,freycinet's 8,hydrog4 ,mem4074   
,these  reefs project about a quarter of

 a mile from the shore2 coloured        
red4--,tinian4 ,the eastern coast is    
precipitous1 and is without reefs2  but 
the western side is fringed like the    
last island2 coloured  red4--,saypan4   
,the ,n4,e4 coast1 and likewise the     
western shores appear  to be fringed2   
but there is a great1 irregular1        
horn-like reef  projecting far from this
 side2 coloured red4--,farallon de      
,medinilla1  appears so regularly and   
closely fringed in ,freycinet's charts1 
that ,i  have ventured to colour it red1
 although nothing is said about reefs in
  the 8,hydrographical ,memoir40 ,the   
several islands which form the  northern
 part of the group are volcanic 7with   
the exception perhaps of  ,torres1 which
 resembles in form the madreporitic     
island of ,medinilla71  and appear to be
 without reefs4--,mangs1 however1 is    
described 7by  ,freycinet1 page #bai1   
8,hydrog407 from some ,spanish charts1  
as formed of  small islands placed 8au  
milieu des nombreux rcifs20 and as these

  reefs in the general chart of the     
group do not project so much as a  mile2
 and as there is no appearance from a   
double line1 of the  existence of deep  
water within1 ,i have ventured1 although
 with much  hesitation1 to colour them  
red4 ,respecting ,folger and ,marshall  
,islands which lie some way east of the 
,marianas1 ,i can find out  nothing1    
excepting that they are probably low4   
,krusenstern says this of  ,marshall    
,island2 and ,folger ,island is written 
with small letters in  ,d',urville's    
chart2 uncoloured4    ,,bonin or        
,,arzobispo ,,group4--,peel ,island  has
 been examined by ,captain  ,beechey1 to
 whose kindness ,i am much indebted for 
giving me information  regarding it3    
8,at ,port ,lloyd there is a great deal 
of coral2 and the  inner harbour is     
entirely formed by coral-reefs1 which   
extend outside  the port along the      
coast40 ,captain ,beechey1 in another   
part of his  letter to me1 alludes to   
the reefs fringing the island in all    

directions2 but at the same time it must
 be observed that the surf  washes the  
volcanic rocks of the coast in the      
greater part of its  circumference4 ,i  
do not know whether the other islands of
 the  ,archipelago are fringed2 ,i have 
coloured ,peel ,island red4--,grampus   
,island to the eastward1 does not appear
 7,meare's 8,voyage10 page #ie7 to  have
 any reefs1 nor does ,rosario ,island   
7from ,lutk's chart71 which  lies to the
 westward4 ,respecting the few other    
islands in this part of  the sea1 namely
 the ,sulphur ,islands1 with an active  
volcano1 and  those lying between ,bonin
 and ,japan 7which are situated near the
  extreme limit in latitude1 at which   
reefs are formed71 ,i have not been     
able to find any clear account4         
,,west ,,end ,,of ,,new ,,guinea4--,port
 ,dory4 ,from the charts in the 8,voyage
 of  the #8,coquille'10 it would appear 
that the coast in this part is fringed  
by coral-reefs2 ,m4 ,lesson1 however1   
remarks that the coral is sickly2       

coloured red4--,waigiou4 ,a considerable
 portion of the northern shores  of     
these islands is seen in the charts 7on 
a large scale7 in  ,freycinet's 8,atlas0
 to be fringed by coral-reefs4 ,forrest 
7page #ba1  8,voyage to ,new ,guinea07  
alludes to the coral-reefs lining the   
heads of  ,piapis ,bay2 and ,horsburgh  
7volume ii41 page #eii1 #dth edition71  
speaking  of the islands in ,dampier    
,strait1 says 8sharp coral-rocks line   
their  shores20 coloured red4--,in the  
sea north of these islands1 we have     
,guedes 7or ,freewill1 or ,st4          
,david's71 which from the chart given   
in the #dto edition of ,carteret's      
8,voyage10 must be an atoll4            
,krusenstern says the islets are very   
low2 coloured blue4--,carteret's        
,shoals1 in #b #ec ,n41 are described as
 circular1 with stony points  showing   
all round1 with deeper water in the     
middle2 coloured  blue4--,aiou2 the plan
 of this group1 given in the 8,atlas of 
the ,voyage  of the #8,astrolabe'10     

shows that it is an atoll2 and1 from a  
chart in  ,forrest's 8,voyage10 it      
appears that there is twelve fathoms    
within the  circular reef2 coloured     
blue4--,the ,s4,w4 coast of ,new ,guinea
 appears to  be low1 muddy1 and devoid  
of reefs4 ,the ,arru1 ,timor laut1 and  
,tenimber groups have lately been       
examined by ,captain ,kolff1 the ,,ms4  
translation of which1 by ,mr4 ,w4 ,earl1
 ,i have been permitted to read1        
through the kindness of ,captain        
,washington1 ,r4,n4 ,these islands are  
mostly rather low1 and are surrounded by
 distant reefs 7the ,ki ,islands1       
however1 are lofty1 and1 from ,mr4      
,stanley's survey1 appear without       
reefs72 the sea in some parts is        
shallow1 in others profoundly deep 7as  
near ,larrat74 ,from the imperfection of
 the published charts1 ,i have  been    
unable to decide to which class these   
reefs belong4 ,from the  distance to    
which they extend from the land1 where  
the sea is very  deep1 ,i am strongly   

inclined to believe they ought to come  
within the  barrier class1 and be       
coloured blue2 but ,i have been forced  
to leave  them uncoloured4--,the        
last-mentioned groups are connected with
 the east  end of ,ceram by a chain of  
small islands1 of which the small groups
 of  ,ceram-laut1 ,goram and ,keffing   
are surrounded by very extensive  reefs1
 projecting into deep water1 which1 as  
in the last case1 ,i  strongly suspect  
belong to the barrier class2 but ,i have
 not coloured  them4 ,from the south    
side of ,keffing1 the reefs project five
 miles  7,windsor ,earl's 8,sailing     
,direct4 for the ,arafura ,sea10 page   
#i74    ,,ceram4--,in various charts    
which ,i have examined1 several parts of
 the  coast are represented as fringed  
by reefs4--,manipa ,island1 between     
,ceram and ,bourou1 in an old ,,ms4     
chart in the ,admiralty1 is fringed by a
  very irregular reef1 partly dry at low
 water1 which ,i do not doubt is  of    
coral-formation2 both islands coloured  

red4--,bourou2 parts of this  island    
appear fringed by coral-reefs1 namely1  
the eastern coast1 as  seen in          
,freycinet's chart2 and ,cajeli ,bay1   
which is said by ,horsburgh  7volume    
ii41 page #fcj7 to be lined by          
coral-reefs1 that stretch out a  little 
way1 and have only a few feet water on  
them4 ,in several charts1  portions of  
the islands forming the ,,amboina       
,,group are fringed by reefs2  for      
instance1 ,noessa1 ,harenca1 and        
,ucaster1 in ,freycinet's  charts4 ,the 
above-mentioned islands have been       
coloured red1 although  the evidence is 
not very satisfactory4--,north of       
,bourou the parallel  line of the ,xulla
 ,isles extends3 ,i have not been able  
to find out  anything about them1       
excepting that ,horsburgh 7volume ii41  
page #edc7  says that the northern shore
 is surrounded by a reef at the distance
 of  two or three miles2                
uncoloured4--,mysol ,group2 the ,kanary 
,islands are  said by ,forrest          

78,voyage10 page #acj7 to be divided    
from each other by  deep straits1 and   
are lined with coral-rocks2 coloured    
red4--,guebe1  lying between ,waigiou   
and ,gilolo1 is engraved as if fringed2 
and it is  said by ,freycinet1 that all 
the soundings under five fathoms were on
  coral2 coloured red4--,gilolo4 ,in a  
chart published by ,dalrymple1 the      
numerous islands on the western1        
southern 7,batchian and the ,strait  of 
,patientia71 and eastern sides appear   
fringed by narrow reefs2 these  reefs1  
,i suppose1 are of coral1 for it is said
 in 8,malte ,brun0 7volume  xii41 page  
#aef71 8,sur les cotes 7of ,batchian7   
comme dans le plupart  des iles de cet  
archipel1 il y a de rocs de medrepores  
d'une beaut et  d'une varit infinies40  
,forrest1 also 7page #ej71 says ,seland1
 near  ,batchian1 is a little island    
with reefs of coral2 coloured           
red4--,morty  ,island 7north of         
,gilolo74 ,horsburgh 7volume ii41 page  
#ejf7 says the  northern coast is lined 

by reefs1 projecting one or two miles1  
and  having no soundings close to them2 
,i have left it uncoloured1 although1   
as in some former cases1 it ought       
probably to be pale blue4--,celebes4    
,the western and northern coasts appear 
in the charts to be bold and  without   
reefs4 ,near the extreme northern point1
 however1 an islet in  the ,straits of  
,limbe1 and parts of the adjoining      
shore1 appear to be  fringed3 the east  
side of the bay of ,manado1 has deep    
water1 and is  fringed by sand and coral
 78#8,astrol4' ,voyage10 ,hydrog4 ,part1
 pages  #dec-d72 this extreme point1    
therefore1 ,i have coloured red4--,of   
the  islands leading from this point to 
,magindanao1 ,i have not been able to   
find any account1 except of ,serangani1 
which appears surrounded by  narrow     
reefs2 and ,forrest 78,voyage10 page    
#afd7 speaks of coral on its  shores2 ,i
 have1 therefore1 coloured this island  
red4 ,to the eastward of  this chain lie
 several islands2 of which ,i cannot    

find any account1  except of ,karkalang1
 which is said by ,horsburgh 7volume    
ii41 page  #ejd7 to be lined by a       
dangerous reef1 projecting several miles
 from the  northern shore2 not coloured4
    ,,islands ,,near ,,timor4--,the     
account of the following islands is     
taken from  ,captain ,d4 ,kolff's       
8,voyage10 in #ahbe1 translated by ,mr4 
,w4 ,earl1 from  the ,dutch4--,lette has
 8reefs extending along shore at the    
distance of  half a mile from the       
land40--,moa has reefs on the ,s4,w4    
part4--,lakor  has a reef lining its    
shore2 these islands are coloured       
red4--,still more  eastward1 ,luan has1 
differently from the last-mentioned     
islands1 an  extensive reef2 it is steep
 outside1 and within there is a depth of
  twelve feet2 from these facts1 it is  
impossible to decide to which  class    
this island belongs4--,kissa1 off the   
point of ,timor1 has its  8shore fronted
 by a reef1 steep too on the outer side1
 over which small  proahs can go at the 

time of high water20 coloured           
red4--,timor2 most  of the points1 and  
some considerable spaces of the northern
 shore1 are  seen in ,freycinet's chart 
to be fringed by coral-reefs2 and       
mention is  made of them in the         
accompanying 8,hydrog4 ,memoir20        
coloured  red4--,savu1 ,s4,e4 of ,timor1
 appears in ,flinders' chart to be      
fringed2  but ,i have not coloured it1  
as ,i do not know that the reefs are of 
coral4-- ,sandalwood ,island has1       
according to ,horsburgh 7volume ii41    
page #fjg71 a reef on its southern      
shore1 four miles distant from the      
land2 as the neighbouring sea is deep1  
and generally bold1 this  probably is a 
barrier- reef1 but ,i have not ventured 
to colour it4    ,n4,w4 ,,coast ,,of    
,,australia4--,it appears1 in ,captain  
,king's ,sailing  ,directions           
78,narrative of ,survey10 volume ii1    
pages #cbe-cfi71 that  there are many   
extensive coral-reefs skirting1 often at
 considerable  distances1 the ,n4,w4    

shores1 and encompassing the small      
adjoining  islets4 ,deep water1 in no   
instance1 is represented in the charts  
between these reefs and the land2 and1  
therefore1 they probably belong  to the 
fringing class4 ,but as they extend far 
into the sea1 which is  generally       
shallow1 even in places where the land  
seems to be somewhat  precipitous2 ,i   
have not coloured them4 ,houtman's      
,abrolhos 7latitude #bh  ,s4 on west    
coast7 have lately been surveyed by     
,captain ,wickham 7as  described in     
8,naut4 ,mag40 #ahda1 page #eaa73 they  
lie on the edge of a  steeply shelving  
bank1 which extends about thirty miles  
seaward1 along  the whole line of coast4
 ,the two southern reefs1 or islands1   
enclose a  lagoon-like space of water1  
varying in depth from five to fifteen   
fathoms1 and in one spot with           
twenty-three fathoms4 ,the greater part 
of  the island has been formed on their 
inland sides1 by the accumulation  of   
fragments of coral2 the seaward face    

consisting of nearly bare  ledges of    
rock4 ,some of the specimens1 brought   
home by ,captain ,wickham1  contained   
fragments of marine shells1 but others  
did not2 and these  closely resembled a 
formation at ,king ,george's ,sound1    
principally due  to the action of the   
wind on calcareous dust1 which ,i shall 
describe in  a forthcoming part4 ,from  
the extreme irregularity of these reefs 
with  their lagoons1 and from their     
position on a bank1 the usual depth of  
which is only thirty fathoms1 ,i have   
not ventured to class them with  atolls1
 and hence have left them               
uncoloured4--,rowley ,shoals4 ,these lie
  some way from the ,n4,w4 coast of     
,australia3 according to ,captain ,king 
78,narrative of ,survey10 volume i41    
page #fj71 they are of  coral-formation4
 ,they rise abruptly from the sea1 and  
,captain ,king had  no bottom with #agj 
fathoms close to them4 ,three of them   
are  crescent-shaped2 they are mentioned
 by ,mr4 ,lyell1 on the authority of    

,captain ,king1 with reference to the   
direction of their open sides4 8,a      
third oval reef of the same group is    
entirely submerged0 78,principles  of   
,geology10 book iii4 chapter xviii472   
coloured blue4--,scott's ,reefs1  lying 
north of ,rowley ,shoals1 are briefly   
described by ,captain ,wickham  78,naut4
 ,mag40 #ahda1 page #ddj73 they appear  
to be of great size1 of a  circular     
form1 and 8with smooth water within1    
forming probably a lagoon  of great     
extent40 ,there is a break on the       
western side1 where there  probably is  
an entrance3 the water is very deep off 
these reefs2  coloured blue4            
,proceeding westward along the great    
volcanic chain of the ,east ,indian     
,archipelago1 ,solor ,strait is         
represented in a chart published by     
,dalrymple from a ,dutch ,,ms41 as      
fringed2 as are parts of ,flores1 of    
,adenara1 and of ,solor4 ,horsburgh     
speaks of coral growing on these        
shores2 and therefore ,i have no doubt  

that the reefs are of coral1 and        
accordingly have coloured them red4 ,we 
hear from ,horsburgh 7volume ii41  page 
#fjb7 that a coral-flat bounds the      
shores of ,sapy ,bay4 ,from the  same   
authority it appears 7page #faj7 that   
reefs fringe the island of              
,timor-,young1 on the ,n4 shore of      
,sumbawa2 and1 likewise 7page #fjj71    
that ,bally town in ,lombock1 is fronted
 by a reef1 stretching along  the shore 
at a distance of a hundred fathoms1 with
 channels through it  for boats2 these  
places1 therefore1 have been coloured   
red4--,bally  ,island4 ,in a ,dutch     
,,ms4 chart on a large scale of ,java1  
which was  brought from that island by  
,dr4 ,horsfield1 who had the kindness to
 show  it me at the ,india ,house1 its  
western1 northern1 and southern shores  
appear very regularly fringed by a reef 
7see also ,horsburgh1 volume  ii41 page 
#eic72 and as coral is found abundantly 
there1 ,i have not the  least doubt that
 the reef is of coral1 and therefore    

have coloured it  red4    ,,java4--,my  
information regarding the reefs of this 
great island is  derived from the chart 
just mentioned4 ,the greater part of    
,madura is  represented in it as        
regularly fringed1 and likewise portions
 of the  coast of ,java immediately     
south of it4 ,dr4 ,horsfield informs me 
that  coral is very abundant near       
,sourabaya4 ,the islets and parts of the
 ,n4  coast of ,java1 west of ,point    
,buang1 or ,japara1 are fringed by      
reefs1 said to be of coral4 ,lubeck1 or 
,bavian ,islands1 lying at  some        
distance from the shore of ,java1 are   
regularly fringed by  coral-reefs4      
,carimon ,java appears equally so1      
though it is not  directly said that the
 reefs are of coral2 there is a depth   
between  thirty and forty fathoms round 
these islands4 ,parts of the shores of  
,sunda ,strait1 where the water is from 
forty to eighty fathoms deep1  and the  
islets near ,batavia appear in several  
charts to be fringed4  ,in the ,dutch   

chart the southern shore1 in the        
narrowest part of the  island1 is in two
 places fringed by reefs of coral4 ,west
 of  ,segorrowodee ,bay1 and the extreme
 ,s4,e4 and ,e4 portions are likewise   
fringed by coral-reefs2 all the         
above-mentioned places coloured red4    
,macassar ,strait2 the east coast of    
,borneo appears1 in most parts1  free   
from reefs1 and where they occur1 as on 
the east coast of  ,pamaroong1 the sea  
is very shallow2 hence no part is       
coloured4 ,in  ,macassar ,strait itself1
 in about latitude #b ,s41 there are    
many small  islands with coral-shoals   
projecting far from them4 ,there are    
also 7old  charts by ,dalrymple7        
numerous little flats of coral1 not     
rising to the  surface of the water1 and
 shelving suddenly from five fathoms to 
no  bottom with fifty fathoms2 they do  
not appear to have a lagoon-like        
structure4 ,there are similar           
coral-shoals a little farther south2 and
  in latitude #d #ee there are two1     

which are engraved from modern  surveys1
 in a manner which might represent an   
annular reef with deep  water inside3   
,captain ,moresby1 however1 who was     
formerly in this sea1  doubts this fact1
 so that ,i have left them uncoloured3  
at the same time  ,i may remark1 that   
these two shoals make a nearer approach 
to the  atoll-like structure than any   
other within the ,e4 ,indian            
,archipelago4  ,southward of these      
shoals there are other low islands and  
irregular  coral-reefs2 and in the space
 of sea1 north of the great volcanic    
chain1 from ,timor to ,java1 we have    
also other islands1 such as the         
,postillions1 ,kalatoa1 ,tokan-,bessees1
 c41 which are chiefly low1  and are    
surrounded by very irregular and distant
 reefs4 ,from the  imperfect charts ,i  
have seen1 ,i have not been able to     
decide whether  they belong to the atoll
 or barrier-classes1 or whether they    
merely  fringe submarine banks1 and     
gently sloping land4 ,in the ,bay of    

,bonin1  between the two southern arms  
of ,celebes1 there are numerous coral-  
reefs2 but none of them seem to have an 
atoll-like structure4 ,i have1          
therefore1 not coloured any of the      
islands in this part of the sea2 ,i     
think it1 however1 exceedingly probable 
that some of them ought to be  blue4 ,i 
may add that there is a harbour on the  
,s4,e4 coast of ,bouton  which1         
according to an old chart1 is formed by 
a reef1 parallel to the  shore1 with    
deep water within2 and in the 8,voyage  
of the #8,coquille'10  some neighbouring
 islands are represented with reefs a   
good way  distant1 but ,i do not know   
whether with deep water within4 ,i have 
not  thought the evidence sufficient to 
permit me to colour them4               
,,sumatra4--,commencing with the west   
coast and outlying islands1 ,engano     
,island is represented in the published 
chart as surrounded by a narrow  reef1  
and ,napier1 in his 8,sailing           
,directions10 speaks of the reef being  

of coral 7also ,horsburgh1 volume ii41  
page #aae72 coloured red4--,rat  ,island
 7#c #ea ,s47 is surrounded by reefs of 
coral1 partly dry at low  water1        
7,horsburgh1 volume ii41 page           
#if74--,trieste ,island 7#d #b ,s474    
,the shore is represented in a chart    
which ,i saw at the ,india ,house1 as   
fringed in such a manner1 that ,i feel  
sure the fringe consists of  coral2 but 
as the island is so low1 that the sea   
sometimes flows quite  over it          
7,dampier1 8,voyage10 volume i41 page   
#dgd71 ,i have not coloured  it4--,pulo 
,dooa 7latitude #c74 ,in an old chart it
 is said there are  chasms in the reefs 
round the island1 admitting boats to the
  watering-place1 and that the southern 
islet consists of a mass of sand  and   
coral4--,pulo ,pisang2 ,horsburgh       
7volume ii41 page #hf7 says that the    
rocky coral-bank1 which stretches about 
forty yards from the shore1 is  steep to
 all round3 in a chart1 also1 which ,i  
have seen1 the island is  represented as

 regularly fringed4--,pulo ,mintao is   
lined with reefs on  its west side      
7,horsburgh1 volume ii41 page           
#ajg74--,pulo ,baniak2 the  same        
authority 7volume ii41 page #aje71      
speaking of a part1 says it is  faced   
with coral-rocks4--,minguin 7#c #cf     
,n474 ,a coral-reef fronts this  place1 
and projects into the sea nearly a      
quarter of a mile 78,notices  of the    
,indian ,arch40 published at ,singapore1
 page #aje74--,pulo ,brassa  7#e #df    
,n474 ,a reef surrounds it at a cable's 
length 7,horsburgh1 volume  ii41 page   
#fj74 ,i have coloured all the          
above-specified points red4 ,i  may here
 add1 that both ,horsburgh and ,mr4     
,moor 7in the 8,notices0 just  alluded  
to7 frequently speak of the numerous    
reefs and banks of coral  on the west   
coast of ,sumatra2 but these nowhere    
have the structure of a  barrier-reef1  
and ,marsden 78,history of ,sumatra07   
states1 that where the  coast is flat1  
the fringing-reefs extend furthest from 

it4 ,the northern  and southern points1 
and the greater part of the east coast1 
are low1  and faced with mud banks1 and 
therefore without coral4    ,,nicobar   
,,islands4--,the chart represents the   
islands of this group as  fringed by    
reefs4 ,with regard to ,great ,nicobar1 
,captain ,moresby  informs me1 that it  
is fringed by reefs of coral1 extending 
between two  and three hundred yards    
from the shore4 ,the ,northern ,nicobars
 appear  so regularly fringed in the    
published charts1 that ,i have no doubt 
the  reefs are of coral4 ,this group1   
therefore1 is coloured red4    ,,andaman
 ,,islands4--,from an examination of the
 ,,ms4 chart1 on a large  scale1 of this
 island1 by ,captain ,arch4 ,blair1 in  
the ,admiralty1  several portions of the
 coast appear fringed2 and as ,horsburgh
 speaks  of coral-reefs being numerous  
in the vicinity of these islands1 ,i    
should have coloured them red1 had not  
some expressions in a paper in  the     
8,asiatic ,researches0 7volume iv41 page

 #djb7 led me to doubt the  existence of
 reefs2 uncoloured4    ,the coast of    
,malacca1 ,tenasserim and the coasts    
northward1 appear  in the greater part  
to be low and muddy3 where reefs occur1 
as in parts  of ,malacca ,straits1 and  
near ,singapore1 they are of the        
fringing  kind2 but the water is so     
shoal1 that ,i have not coloured them4  
,in the  sea1 however1 between ,malacca 
and the west coast of ,borneo1 where    
there  is a greater depth from forty to 
fifty fathoms1 ,i have coloured red     
some of the groups1 which are regularly 
fringed4 ,the northern ,natunas  and the
 ,anambas ,islands are represented in   
the charts on a large  scale1 published 
in the 8,atlas of the ,voyage of the    
#8,favourite'10 as  fringed by reefs of 
coral1 with very shoal water within     
them4--,tumbelan and ,bunoa ,islands 7#a
 ,n47 are represented in the  ,english  
charts as surrounded by a very regular  
fringe4-- ,st4 ,barbes  7#j #ae ,n47 is 
said by ,horsburgh 7volume ii41 page    

#bgi7 to be fronted  by a reef1 over    
which boats can land only at high       
water4--,the shore of  ,borneo at       
,tunjong ,apee is also fronted by a     
reef1 extending not far  from the land  
7,horsburgh1 volume ii41 page #dfh74    
,these places ,i have  coloured red2    
although with some hesitation1 as the   
water is shallow4 ,i  might perhaps have
 added ,pulo ,leat1 in ,gaspar ,strait1 
,lucepara1 and  ,carimata2 but as the   
sea is confined and shallow1 and the    
reefs not  very regular1 ,i have left   
them uncoloured4    ,the water shoals   
gradually towards the whole west coast  
of ,borneo3 ,i  cannot make out that it 
has any reefs of coral4 ,the islands1   
however1  off the northern extremity1   
and near the ,s4,w4 end of ,palawan1 are
  fringed by very distant coral-reefs2  
thus the reefs in the case of  ,balabac 
are no less than five miles from the    
land2 but the sea1 in  the whole of this
 district1 is so shallow1 that the reefs
 might be  expected to extend very far  

from the land4 ,i have not1 therefore1  
thought myself authorised to colour     
them4 ,the ,n4,e4 point of ,borneo1     
where the water is very shoal1 is       
connected with ,magindanao by a chain   
of islands called the ,sooloo           
,archipelago1 about which ,i have been  
able to obtain very little information2 
,pangootaran1 although ten  miles long1 
entirely consists of a bed of coral-rock
 78,notices of ,e4  ,indian ,arch40 page
 #eh73 ,i believe from ,horsburgh that  
the island is  low2 not                 
coloured4--,tahow ,bank1 in some old    
charts1 appears like a  submerged atoll2
 not coloured4 ,forrest 78,voyage10 page
 #ba7 states that  one of the islands   
near ,sooloo is surrounded by           
coral-rocks2 but there  is no distant   
reef4 ,near the ,s4 end of ,basselan1   
some of the islets  in the chart        
accompanying ,forrest's 8,voyage10      
appear fringed with  reefs2 hence ,i    
have coloured1 though unwillingly1 parts
 of the ,sooloo  group red4 ,the sea    

between ,sooloo and ,palawan1 near the  
shoal coast of  ,borneo1 is interspersed
 with irregular reefs and shoal patches2
 not  coloured3 but in the northern part
 of this sea1 there are two low  islets1
 ,cagayanes and ,cavilli1 surrounded by 
extensive coral-reefs2  the breakers    
round the latter 7,horsburgh1 volume    
ii41 page #eac7 extend  five or six     
miles from a sandbank1 which forms the  
only dry part2 these  breakers are steep
 to outside2 there appears to be an     
opening through  them on one side1 with 
four or five fathoms within3 from this  
description1 ,i strongly suspect that   
,cavilli ought to be considered an      
atoll2 but1 as ,i have not seen any     
chart of it1 on even a moderately  large
 scale1 ,i have not coloured it4 ,the   
islets off the northern end of          
,palawan1 are in the same case as those 
off the southern end1 namely  they are  
fringed by reefs1 some way distant from 
the shore1 but the  water is exceedingly
 shallow2 uncoloured4 ,the western shore

 of ,palawan  will be treated of under  
the head of ,china ,sea4    ,,philippine
 ,,archipelago4--,a chart on a large    
scale of ,appoo shoal1  which lies near 
the ,s4,e4 coast of ,mindoro1 has been  
executed by ,captain  ,d4 ,ross3 it     
appears atoll-formed1 but with rather an
 irregular outline2  its diameter is    
about ten miles2 there are two          
well-defined passages  leading into the 
interior lagoon1 which appears open2    
close outside the  reef all round1 there
 is no bottom with seventy fathoms2     
coloured  blue4--,mindoro3 the ,n4,w4   
coast is represented in several charts1 
as  fringed by a reef1 and ,luban       
,island is said1 by ,horsburgh 7volume  
ii41 page #dcf71 to be 8lined by a      
reef40--,luzon3 ,mr4 ,cuming1 who has   
lately investigated with so much success
 the ,natural ,history of the           
,philippines1 informs me1 that about    
three miles of the shore north of       
,point ,st4 ,jago1 is fringed by a reef2
 as are 7,horsburgh1 volume ii41  page  

#dcg7 the ,three ,friars off ,silanguin 
,bay4 ,between ,point ,capones and      
,playa ,honda1 the coast is 8lined by a 
coral-reef1 stretching out nearly  a    
mile in some places10 7,horsburgh72 and 
,mr4 ,cuming visited some  fringing-    
reefs on parts of this coast1 namely1   
near ,puebla1 ,iba1 and  ,mansinglor4   
,in the neighbourhood of ,solon-solon   
,bay1 the shore is lined  7,horsburgh   
ii41 page #dci7 by coral-reefs1         
stretching out a great way3  there are  
also reefs about the islets off         
,solamague2 and as ,i am  informed by   
,mr4 ,cuming1 near ,st4 ,catalina1 and a
 little north of it4  ,the same         
gentleman informs me there are reefs on 
the ,s4,e4 point of this  island in     
front of ,samar1 extending from         
,malalabon to ,bulusan4 ,these  appear  
to be the principal fringing-reefs on   
the coasts of ,luzon2 and  they have all
 been coloured red4 ,mr4 ,cuming informs
 me that none of  them have deep water  
within2 although it appears from        

,horsburgh that  some few extend to a   
considerable distance from the shore4   
,within the  ,philippine ,archipelago1  
the shores of the islands do not appear 
to be  commonly fringed1 with the       
exception of the ,s4 shore of ,masbate1 
and  nearly the whole of ,bohol2 which  
are both coloured red4 ,on the ,s4      
shore of ,magindanao1 ,bunwoot ,island  
is surrounded 7according to  ,forrest1  
8,voyage10 page #bec71 by a coral-reef1 
which in the chart  appears one of the  
fringing class4 ,with respect to the    
eastern coasts  of the whole            
,archipelago1 ,i have not been able to  
obtain any account4    ,,babuyan        
,,islands4--,horsburgh says 7volume ii41
 page #ddb71 coral-reefs  line the      
shores of the harbour in ,fuga2 and the 
charts show there are  other reefs about
 these islands4 ,camiguin has its shore 
in parts  lined by coral-rock           
7,horsburgh1 page #ddc72 about a mile   
off shore there  is between thirty and  
thirty-five fathoms4 ,the plan of ,port 

,san ,pio  ,quinto shows that its shores
 are fringed with coral2 coloured       
red4--,,babuyan ,,islands3 ,horsburgh1  
speaking of the southern part of the    
group 7volume ii41 page #dde7 says the  
shores of both islands are  fortified by
 a reef1 and through some of the gaps in
 it1 the natives  can pass in their     
boats in fine weather2 the bottom near  
the land is  coral-rock4 ,from the      
published charts1 it is evident that    
several of  these islands are most      
regularly fringed2 coloured red4 ,the   
northern  islands are left uncoloured1  
as ,i have been unable to find any      
account  of them4--,,formosa4 ,the      
shores1 especially the western one1 seem
 chiefly  composed of mud and sand1 and 
,i cannot make out that they are        
anywhere  lined by reefs2 except in a   
harbour 7,horsburgh1 volume ii41 page   
#ddi7  at the extreme northern point3   
hence1 of course1 the whole of this     
island is left uncoloured4 ,the small   
adjoining islands are in the same       

case4-- ,,patchow1 or ,,madjiko-,,sima  
,,groups4 ,patchuson has been described 
by ,captain ,broughton 78,voy4 to the   
,n4 ,pacific10 page #aia72 he says1 the 
boats1 with some difficulty1 found a    
passage through the coral-reefs1  which 
extend along the coast1 nearly half a   
mile off it4 ,the boats were  well      
sheltered within the reef2 but it does  
not appear that the water  is deep      
there4 ,outside the reef the depth is   
very irregular1 varying  from five to   
fifty fathoms2 the form of the land is  
not very abrupt2  coloured              
red4--,taypin-san2 from the description 
given 7page #aie7 by  the same author1  
it appears that a very irregular reef   
extends1 to the  distance of several    
miles1 from the southern island2 but    
whether it  encircles a space of deep   
water is not evident2 nor1 indeed1      
whether  these outlying reefs are       
connected with those more immediately   
adjoining the land2 left uncoloured4 ,i 
may here just add that the shore  of    

,kumi 7lying west of ,patchow71 has a   
narrow reef attached to it in  the plan 
of it1 in ,la ,peyrouse's 8,atlas20 but 
it does not appear in the  account of   
the voyage that it is of coral2         
uncoloured4--,,loo ,,choo4 ,the  greater
 part of the coast of this moderately   
hilly island1 is skirted  by reefs1     
which do not extend far from the shore1 
and which do not  leave a channel of    
deep water within them1 as may be seen  
in the charts  accompanying ,captain ,b4
 ,hall's voyage to ,loo ,choo 7see also 
remarks in  ,appendix1 pages xxi4 and   
xxv474 ,there are1 however1 some ports  
with  deep water1 formed by reefs in    
front of valleys1 in the same manner as 
happens at ,mauritius4 ,captain         
,beechey1 in a letter to me1 compares   
these reefs with those encircling the   
,society ,islands2 but there  appears to
 me a marked difference between them1 in
 the less distance at  which the ,loo   
,choo reefs lie from the land with      
relation to the  probable submarine     

inclination1 and in the absence of an   
interior deep  water-moat or channel1   
parallel to the land4 ,hence1 ,i have   
classed  these reefs with               
fringing-reefs1 and coloured them       
red4--,,pescadores  7west of ,formosa74 
,dampier 7volume i41 page #daf71 has    
compared the  appearance of the land to 
the southern parts of ,england4 ,the    
islands  are interlaced with            
coral-reefs2 but as the water is very   
shoal1 and as  spits of sand and gravel 
7,horsburgh1 volume ii41 page #dej7     
extend far  out from them1 it is        
impossible to draw any inferences       
regarding the  nature of the reefs4     
,,china ,,sea4--,proceeding from north  
to south1 we first meet the ,pratas     
,shoal 7latitude #bj ,n47 which1        
according to ,horsburgh 7volume ii41    
page #cce71 is composed of coral1 is of 
a circular form1 and has a low  islet on
 it4 ,the reef is on a level with the   
water's edge1 and when the  sea runs    
high1 there are breakers mostly all     

round1 8but the water  within seems     
pretty deep in some places2 although    
steep-to in most  parts outside1 there  
appear to be several parts where a ship 
might find  anchorage outside the       
breakers20 coloured blue4--,the         
,paracells have  been accurately        
surveyed by ,captain ,d4 ,ross1 and     
charts on a large  scale published3 but 
few low islets have been formed on these
 shoals1  and this seems to be a general
 circumstance in the ,china ,sea2 the   
sea  close outside the reefs is very    
deep2 several of them have a            
lagoon-like structure2 or separate      
islets 7,prattle1 ,robert1  ,drummond1  
etc47 are so arranged round a moderately
 shallow space1 as  to appear as if they
 had once formed one large atoll4--     
,bombay ,shoal  7one of the ,paracells7 
has the form of an annular reef1 and is 
8apparently deep within20 it seems to   
have an entrance 7,horsburgh1  volume   
ii41 page #ccb7 on its west side2 it is 
very steep  outside4--,discovery ,shoal1

 also is of an oval form1 with a        
lagoon-like  space within1 and three    
openings leading into it1 in which there
 is a  depth from two to twenty fathoms4
 ,outside1 at the distance 7,horsburgh1 
volume ii41 page #ccc7 of only twenty   
yards from the reef1 soundings  could   
not be obtained4 ,the ,paracells are    
coloured blue4--,macclesfield  ,bank3   
this is a coral-bank of great size1     
lying east of the ,paracells2  some     
parts of the bank are level1 with a     
sandy bottom1 but1 generally1  the depth
 is very irregular4 ,it is intersected  
by deep cuts or  channels4 ,i am not    
able to perceive in the published charts
 7its  limits1 however1 are not very    
accurately known7 whether the central   
part is deeper1 which ,i suspect is the 
case1 as in the ,great ,chagos  ,bank1  
in the ,indian ,ocean2 not              
coloured4--,scarborough ,shoal3 this    
coral-shoal is engraved with a double   
row of crosses1 forming a circle1  as if
 there was deep water within the reef3  

close outside there was no  bottom1 with
 a hundred fathoms2 coloured blue4--,the
 sea off the west  coast of ,palawan and
 the northern part of ,borneo is strewed
 with  shoals3 ,swallow ,shoal1         
according to ,horsburgh 7volume ii41    
page #dca7  8is formed1 like most of the
 shoals hereabouts1 of a belt of        
coral-rocks1 8with a basin of deep water
 within40--,half-,moon ,shoal has  a    
similar structure2 ,captain ,d4 ,ross   
describes it1 as a narrow belt of       
coral-rock1 8with a basin of deep water 
in the centre10 and deep sea  close     
outside4--,bombay ,shoal appears        
7,horsburgh1 volume ii41 page #dcb7  8to
 be a basin of smooth water surrounded  
by breakers40 ,these three  shoals ,i   
have coloured blue4--,the ,paraquas     
,shoals are of a circular  form1 with   
deep gaps running through them2 not     
coloured4--,a bank  gradually shoaling  
to the depth of thirty fathoms1 extends 
to a  distance of about twenty miles    
from the northern part of ,borneo1 and  

to thirty miles from the northern part  
of ,palawan4 ,near the land this  bank  
appears tolerably free from danger1 but 
a little further out it is  thickly     
studded with coral-shoals1 which do not 
generally rise quite to  the surface2   
some of them are very steep-to1 and     
others have a fringe  of shoal-water    
round them4 ,i should have thought that 
these shoals had  level surfaces1 had it
 not been for the statement made by     
,horsburgh  8that most of the shoals    
hereabouts are formed of a belt of      
coral40  ,but1 perhaps that expression  
was more particularly applied to the    
shoals further in the offing4 ,if these 
reefs of coral have a  lagoon-like      
structure1 they should have been        
coloured blue1 and they  would have     
formed an imperfect barrier in front of 
,palawan and the  northern part of      
,borneo4 ,but1 as the water is not very 
deep1 these  reefs may have grown up    
from inequalities on the bank3 ,i have  
not  coloured them4--,the coast of      

,china1 ,tonquin1 and ,cochin-,china1   
forming the western boundary of the     
,china ,sea1 appear to be without       
reefs3 with regard to the two           
last-mentioned coasts1 ,i speak after   
examining the charts on a large scale in
 the 8,atlas of the ,voyage of  the     
#8,favourite'40    ,,indian             
,,ocean4--,south ,keeling has been      
specially described3 nine miles  north  
of it lies ,north ,keeling1 a very small
 atoll1 surveyed by the  8,beagle10 the 
lagoon of which is dry at low           
water4--,christmas ,island1  lying to   
the east1 is a high island1 without1 as 
,i have been informed  by a person who  
passed it1 any reefs at all4--,,ceylon3 
a space about  eighty miles in length of
 the south-western and southern shores  
of  these islands has been described by 
,mr4 ,twynam 78,naut4 ,mag40 #ahcf1     
pages #cfe and #eah72 parts of this     
space appear to be very regularly       
fringed by coral-reefs1 which extend    
from a quarter to half a mile from  the 

shore4 ,these reefs are in places       
breached1 and afford safe  anchorage for
 the small trading craft4 ,outside1 the 
sea gradually  deepens2 there is forty  
fathoms about six miles off shore3 this 
part ,i  have coloured red4 ,in the     
published charts of ,ceylon there appear
 to be  fringing-reefs in several parts 
of the south-eastern shores1 which ,i   
have also coloured red4--,at ,venloos   
,bay the shore is likewise fringed4     
,north of ,trincomalee there are also   
reefs of the same kind4 ,the sea off    
the northern part of ,ceylon is         
exceedingly shallow2 and therefore ,i   
have not coloured the reefs which fringe
 portions of its shores1 and  the       
adjoining islets1 as well as the ,indian
 promontory of ,madura4    ,,chagos1    
,,maldiva1 and ,,laccadive              
,,archipelagoes4--,these three great    
groups  which have already been often   
noticed1 are now well-known from the    
admirable surveys of ,captain ,moresby  
and ,lieutenant ,powell4 ,the  published

 charts1 which are worthy of the most   
attentive examination1  at once show    
that the ,chagos and ,maldiva groups are
 entirely formed  of great atolls1 or   
lagoon-formed reefs1 surmounted by      
islets4 ,in the  ,laccadive group1 this 
structure is less evident2 the islets   
are low1  not exceeding the usual height
 of coral-formations 7see ,lieutenant   
,wood's account1 8,geographical         
,journal01 volume vi41 page #bi71 and   
most  of the reefs are circular1 as may 
be seen in the published charts2 and    
within several of them1 as ,i am        
informed by ,captain ,moresby1 there is 
deepish water2 these1 therefore1 have   
been coloured blue4 ,directly  north1   
and almost forming part of this group1  
there is a long1 narrow1  slightly      
curved bank1 rising out of the depths of
 the ocean1 composed  of sand1 shells1  
and decayed coral1 with from            
twenty-three to thirty  fathoms on it4  
,i have no doubt that it has had the    
same origin with the  other ,laccadive  

banks2 but as it does not deepen towards
 the centre ,i  have not coloured it4 ,i
 might have referred to other           
authorities  regarding these three      
archipelagoes2 but after the publication
 of the  charts by ,captain ,moresby1 to
 whose personal kindness in giving me   
much  information ,i am exceedingly     
indebted1 it would have been            
superfluous4    ,sahia de ,malhabank    
consists of a series of narrow banks1   
with from  eight to sixteen fathoms on  
them2 they are arranged in a            
semicircular  manner1 round a space     
about forty fathoms deep1 which slopes  
on the  ,s4,e4 quarter to unfathomable  
depths2 they are steep-to on both sides1
  but more especially on the ocean-side4
 ,hence this bank closely  resembles in 
structure1 and ,i may add from ,captain 
,moresby's  information in composition1 
the ,pitt's ,bank in the ,chagos group2 
and  the ,pitt's ,bank1 must1 after what
 has been shown of the ,great ,chagos   
,bank1 be considered as a sunken1       

half-destroyed atoll2 hence coloured    
blue4--,cargados ,carajos ,bank4 ,its   
southern portion consists of a  large1  
curved1 coral-shoal1 with some low      
islets on its eastern edge1  and        
likewise some on the western side1      
between which there is a depth  of about
 twelve fathoms4 ,northward1 a great    
bank extends4 ,i cannot  7probably owing
 to the want of perfect charts7 refer   
this reef and bank  to any              
class2--therefore not coloured4--,ile de
 ,sable is a little  island1 lying west 
of ,c4 ,carajos1 only some toises in    
height 78,voyage  of the #8,favourite'10
 volume i41 page #acj72 it is surrounded
 by reefs2  but its structure is        
unintelligible to me4 ,there are some   
small banks  north of it1 of which ,i   
can find no clear account4--,mauritius4 
,the  reefs round this island have been 
described in the chapter on             
fringing-reefs2 coloured red4           
--,rodriguez4 ,the coral-reefs here are 
exceedingly extensive2 in one part they 

project even five miles from  the shore4
 ,as far as ,i can make out1 there is no
 deep-water moat within  them2 and the  
sea outside does not deepen very        
suddenly4 ,the outline1  however1 of the
 land appears to be 78,life of ,sir ,j4 
,makintosh10 volume  ii41 page #afe7    
hilly and rugged4 ,i am unable to decide
 whether these  reefs belong to the     
barrier class2 as seems probable from   
their great  extension1 or to the       
fringing class2 uncoloured4 --,bourbon4 
,the  greater part of the shores of this
 island are without reefs2 but  ,captain
 ,carmichael 7,hooker's 8,bot4 ,misc407 
states that a portion1  fifteen miles in
 length1 on the ,s4,e4 side1 is         
imperfectly fringed with  coral reefs3  
,i have not thought this sufficient to  
colour the island4                      
,,seychelles4--,the rocky islands of    
primary formation1 composing this       
group1 rise from a very extensive and   
tolerably level bank1 having a  depth   
between twenty and forty fathoms4 ,in   

,captain ,owen's chart1 and in  that in 
the 8,atlas of the ,voyage of the       
#8,favourite'10 it appears that  the    
east side of ,mah and the adjoining     
islands of ,st4 ,anne and  ,cerf1 are   
regularly fringed by coral-reefs4 ,a    
portion of the ,s4,e4  part of ,curieuse
 ,island1 the ,n41 and part of the      
,s4,w4 shore of  ,praslin ,island1 and  
the whole west side of ,digue ,island1  
appear  fringed4 ,from a ,,ms4 account  
of these islands by ,captain ,f4        
,moresby1 in  the ,admiralty1 it appears
 that ,silhouette is also fringed2 he   
states  that all these islands are      
formed of granite and quartz1 that they 
rise  abruptly from the sea1 and that   
8coral-reefs have grown round them1 and 
project for some distance40 ,dr4 ,allan1
 of ,forres1 who visited these  islands1
 informs me that there is no deep water 
between the reefs and  the shore4 ,the  
above specified points have been        
coloured red4  ,amirantes ,islands3 ,the
 small islands of this neighbouring     

group1  according to the ,,ms4 account  
of them by ,captain ,f4 ,moresby1 are   
situated on an extensive bank2 they     
consist of the debris of corals and     
shells2 are only about twenty feet in   
height1 and are environed by  reefs1    
some attached to the shore1 and some    
rather distant from it4--,i  have taken 
great pains to procure plans and        
information regarding the  several      
islands lying between ,s4,e4 and ,s4,w4 
of the ,amirantes1 and the  ,seychelles2
 relying chiefly on ,captain ,f4        
,moresby and ,dr4 ,allan1 it  appears   
that the greater number1                
namely--,platte1 ,alphonse1  ,coetivi1  
,galega1 ,providence1 ,st4 ,pierre1     
,astova1  ,assomption1 and ,glorioso1   
are low1 formed of sand or coral-rock1  
and irregularly shaped2 they are        
situated on very extensive banks1 and   
are connected with great coral-reefs4   
,galega is said by ,dr4 ,allan1 to  be  
rather higher than the other islands2   
and ,st4 ,pierre is described by        

,captain ,f4 ,moresby1 as being         
cavernous throughout1 and as not        
consisting of either limestone or       
granite4 ,these islands1 as well as  the
 ,amirantes1 certainly are not          
atoll-formed1 and they differ as a      
group from every other group with which 
,i am acquainted2 ,i have not  coloured 
them2 but probably the reefs belong to  
the fringing class4  ,their formation is
 attributed1 both by ,dr4 ,allan and    
,captain ,f4  ,moresby1 to the action of
 the currents1 here exceedingly violent1
 on  banks1 which no doubt have had an  
independent geological origin4 ,they    
resemble in many respects some islands  
and banks in the ,west ,indies1  which  
owe their origin to a similar agency1 in
 conjunction with an  elevation of the  
entire area4 ,in close vicinity to the  
several islands1  there are three others
 of an apparently different nature3     
first1 ,juan  de ,nova1 which appears   
from some plans and accounts to be an   
atoll2  but from others does not appear 

to be so2 not coloured4 ,secondly       
,cosmoledo2 8this group consists of a   
ring of coral1 ten leagues in           
circumference1 and a quarter of a mile  
broad in some places1 enclosing  a      
magnificent lagoon1 into which there did
 not appear a single opening0           
7,horsburgh1 volume i41 page #aea72     
coloured blue4 ,thirdly1 ,aldabra2 it   
consists of three islets1 about         
twenty-five feet in height1 with red    
cliffs 7,horsburgh1 volume i41 page     
#agf7 surrounding a very shallow  basin 
or lagoon4 ,the sea is profoundly deep  
close to the shore4 ,viewing  this      
island in a chart1 it would be thought  
an atoll2 but the foregoing  description
 shows that there is something different
 in its nature2 ,dr4  ,allan also states
 that it is cavernous1 and that the     
coral-rock has a  vitrified appearance4 
,is it an upheaved atoll1 or the crater 
of a  volcano8--uncoloured4    ,,comoro 
,,group4--,mayotta1 according to        
,horsburgh 7volume i41 page #baf1  #dth 

edition71 is completely surrounded by a 
reef1 which runs at the  distance of    
three1 four1 and in some places even    
five miles from the  land2 in an old    
chart1 published by ,dalrymple1 a depth 
in many places  of thirty-six and       
thirty-eight fathoms is laid down within
 the reef4 ,in  the same chart1 the     
space of open water within the reef in  
some parts  is even more than three     
miles wide3 the land is bold and peaked2
 this  island1 therefore1 is encircled  
by a well-characterised barrier-reef1   
and is coloured pale blue4--,johanna2   
,horsburgh says 7volume ,i4 page  #bag7 
this island from the ,n4,w4 to the      
,s4,w4 point1 is bounded by a reef1  at 
the distance of two miles from the      
shore2 in some parts1 however1  the reef
 must be attached1 since ,lieutenant    
,boteler 78,narr40 volume i41  page     
#afa7 describes a passage through it1   
within which there is room  only for a  
few boats4 ,its height1 as ,i am        
informed by ,dr4 ,allan1 is  about      

#c1ejj feet2 it is very precipitous1 and
 is composed of granite1  greenstone1   
and quartz2 coloured blue4--,mohilla2 on
 the ,s4 side of  this island there is  
anchorage1 in from thirty to forty-five 
fathoms1  between a reef and the shore  
7,horsburgh1 volume i41 page #bad72 in  
,captain ,owen's chart of ,madagascar1  
this island is represented as           
encircled2 coloured blue4--,great       
,comoro ,island is1 as ,i am informed by
  ,dr4 ,allan1 about #h1jjj feet high1  
and apparently volcanic2 it is not      
regularly encircled2 but reefs of       
various shapes and dimensions1 jut  out 
from every headland on the ,w41 ,s41 and
 ,s4,e4 coasts1 inside of which  reefs  
there are channels1 often parallel with 
the shore1 with deep  water4 ,on the    
north-western coasts the reefs appear   
attached to the  shores4 ,the land near 
the coast is in some places bold1 but   
generally  speaking it is flat2         
,horsburgh says 7volume i41 page #bad7  
the water is  profoundly deep close to  

the shore1 from which expression ,i     
presume  some parts are without reefs4  
,from this description ,i apprehend the 
reef belongs to the barrier class2 but  
,i have not coloured it1 as most  of the
 charts which ,i have seen1 represent   
the reefs round it as very  much less   
extensive than round the other islands  
in the group4    ,,madagascar4--,my     
information is chiefly derived from the 
published charts  by ,captain ,owen1 and
 the accounts given by him and by       
,lieutenant  ,boteler4 ,commencing at   
the ,s4,w4 extremity of the island2     
towards the  northern part of the ,star 
,bank 7in latitude #be ,s47 the coast   
for ten  miles is fringed by a reef2    
coloured red4 ,the shore immediately ,s4
 of  ,st4 ,augustine's ,bay appears     
fringed2 but ,tullear ,harbour1 directly
  ,n4 of it1 is formed by a narrow reef 
ten miles long1 extending parallel  to  
the shore1 with from four to ten fathoms
 within it4 ,if this reef had  been more
 extensive1 it must have been classed as

 a barrier-reef2 but  as the line of    
coast falls inwards here1 a submarine   
bank perhaps  extends parallel to the   
shore1 which has offered a foundation   
for the  growth of the coral2 ,i have   
left this part uncoloured4 ,from lat4   
#bb  #af to #ba #cg1 the shore is       
fringed by coral-reefs 7see ,lieutenant 
,boteler's 8,narrative10 volume ii41    
page #ajf71 less than a mile in  width1 
and with shallow water within4 ,there   
are outlying coral-shoals  in several   
parts of the offing1 with about ten     
fathoms between them and  the shore1 and
 the depth of the sea one mile and a    
half seaward1 is  about thirty fathoms4 
,the part above specified is engraved on
 a large  scale2 and as in the charts on
 rather a smaller scale the same fringe 
of reef extends as far as latitude #cc  
#ae2 ,i have coloured the whole  of this
 part of the coast red4 ,the islands of 
,juan de ,nova 7in  latitude #ag ,s47   
appear in the charts on a large scale to
 be fringed1  but ,i have not been able 

to ascertain whether the reefs are of   
coral2  uncoloured4 ,the main part of   
the west coast appears to be low1 with  
outlying sandbanks1 which1 ,lieutenant  
,boteler 7volume ii41 page #ajf7  says1 
8are faced on the edge of deep water by 
a line of sharp-pointed  coral-rocks40  
,nevertheless ,i have not coloured this 
part1 as ,i cannot  make out by the     
charts that the coast itself is fringed4
 ,the headlands  of ,narrenda and       
,passandava ,bays 7#ad #dj7 and the     
islands in front  of ,radama harbour are
 represented in the plans as regularly  
fringed1  and have accordingly been     
coloured red4 ,with respect to the ,east
 coast  of ,madagascar1 ,dr4 ,allan     
informs me in a letter1 that the whole  
line  of coast1 from ,tamatave1 in #ah  
#ab1 to ,c4 ,amber1 at the extreme      
northern point of the island1 is        
bordered by coral-reefs4 ,the land is   
low1 uneven1 and gradually rising from  
the coast4 ,from ,captain ,owen's       
charts1 also1 the existence of these    

reefs1 which evidently belong to  the   
fringing class1 on some parts1 namely   
,n4 of ,british ,sound1 and  near       
,ngoncy1 of the above line of coast     
might have been inferred4  ,lieutenant  
,boteler 7volume i41 page #aee7 speaks  
of 8the reef  surrounding the island of 
,st4 ,mary's at a small distance from   
the  shore40 ,in a previous chapter ,i  
have described1 from the information of 
,dr4 ,allan1 the manner in which the    
reefs extend in ,n4,e4 lines from the   
headlands on this coast1 thus sometimes 
forming rather deep channels  within    
them1 this seems caused by the action of
 the currents1 and the  reefs spring up 
from the submarine prolongations of the 
sandy  headlands4 ,the above specified  
portion of the coast is coloured red4   
,the remaining ,s4,e4 portions do not   
appear in any published chart to        
possess reefs of any kind2 and the ,rev4
 ,w4 ,ellis1 whose means of  information
 regarding this side of ,madagascar have
 been extensive1  informs me he believes

 there are none4    ,,east ,,coast ,,of 
,,africa4--,proceeding from the northern
 part1 the coast  appears1 for a        
considerable space1 without reefs4 ,my  
information1 ,i may  here observe1 is   
derived from the survey by ,captain     
,owen1 together with  his narrative2 and
 that by ,lieutenant ,boteler4 ,at      
,mukdeesha 7#aj #a  ,n47 there is a     
coral-reef extending four or five miles 
along the shore  7,owen's 8,narr40      
volume i1 page #ceg7 which in the chart 
lies at the  distance of a quarter of a 
mile from the shore1 and has within it  
from  six to ten feet water3 this then  
is a fringing-reef1 and is coloured     
red4 ,from ,juba1 a little ,s4 of the   
equator1 to ,lamoo 7in #b #bj ,s47  8the
 coast and islands are formed of        
madrepore0 7,owen's 8,narrative10       
volume i41 page #cfc74 ,the chart of    
this part 7entitled ,dundas  ,islands71 
presents an extraordinary appearance2   
the coast of the  mainland is quite     
straight and it is fronted at the       

average distance of  two miles1 by      
exceedingly narrow1 straight islets1    
fringed with reefs4  ,within the chain  
of islets1 there are extensive tidal    
flats and muddy  bays1 into which many  
rivers enter2 the depths of these spaces
 varies  from one to four fathoms--the  
latter depth not being common1 and about
  twelve feet the average4 ,outside the 
chain of islets1 the sea1 at the        
distance of a mile1 varies in depth from
 eight to fifteen fathoms4  ,lieutenant 
,boteler 78,narr40 volume i41 page #cfi7
 describes the muddy  bay of ,patta1    
which seems to resemble other parts of  
this coast1 as  fronted by small1       
narrow1 level islets formed of          
decomposing coral1 the  margin of which 
is seldom of greater height than twelve 
feet1  overhanging the rocky surface    
from which the islets rise4 ,knowing    
that  the islets are formed of coral1 it
 is1 ,i think1 scarcely possible to     
view the coast1 and not at once conclude
 that we here see a  fringing-reef1     

which has been upraised a few feet3 the 
unusual depth of  from two to four      
fathoms within some of these islets1 is 
probably due  to muddy rivers having    
prevented the growth of coral near the  
shore4  ,there is1 however1 one         
difficulty on this view1 namely1 that   
before the  elevation took place1 which 
converted the reef into a chain of      
islets1  the water must apparently have 
been still deeper2 on the other hand it 
may be supposed that the formation of a 
nearly perfect barrier in  front1 of so 
large an extent of coast1 would cause   
the currents  7especially in front of   
the rivers71 to deepen their muddy beds4
 ,when  describing in the chapter on    
fringing-reefs1 those of ,mauritius1 ,i 
have  given my reasons for believing    
that the shoal spaces within reefs of   
this kind1 must1 in many instances1 have
 been deepened4 ,however this  may be1  
as several parts of this line of coast  
are undoubtedly fringed  by living      
reefs1 ,i have coloured it red4--       

,maleenda 7#c #bj ,s474 ,in  the plan of
 the harbour1 the south headland appears
 fringed2 and in  ,owen's chart on a    
larger scale1 the reefs are seen to     
extend nearly  thirty miles southward2  
coloured red4--,mombas 7#d #e ,s474 ,the
 island  which forms the harbour1 8is   
surrounded by cliffs of madrepore1      
capable  of being rendered almost       
impregnable0 7,owen's 8,narr40 volume   
i41 page  #dab74 ,the shore of the      
mainland ,n4 and ,s4 of the harbour1 is 
most  regularly fringed by a coral-reef 
at a distance from half a mile to one   
mile and a quarter from the land2 within
 the reef the depth is from  nine to    
fifteen feet2 outside the reef the depth
 at rather less than  half a mile is    
thirty fathoms4 ,from the charts it     
appears that a space  about thirty-six  
miles in length1 is here fringed2       
coloured  red4--,pemba 7#e ,s47 is an   
island of coral-formation1 level1 and   
about  two hundred feet in height       
7,owen's 8,narr40 volume i41 page #dbe72

 it is  thirty-five miles long1 and is  
separated from the mainland by a deep   
sea4 ,the outer coast is represented in 
the chart as regularly fringed2         
coloured red4 ,the mainland in front of 
,pemba is likewise fringed2 but  there  
also appear to be some outlying reefs   
with deep water between  them and the   
shore4 ,i do not understand their       
structure1 either from  the charts or   
the description1 therefore have not     
coloured  them4--,zanzibar resembles    
,pemba in most respects2 its southern   
half on  the western side and the       
neighbouring islets are fringed2        
coloured red4  ,on the mainland1 a      
little ,s4 of ,zanzibar1 there are some 
banks parallel  to the coast1 which ,i  
should have thought had been formed of  
coral1 had  it not been said 7,boteler's
 8,narr40 volume ii41 page #ci7 that    
they were  composed of sand2 not        
coloured4--,latham's ,bank is a small   
island1  fringed by coral-reefs2 but    
being only ten feet high1 it has not    

been  coloured4--,monfeea is an island  
of the same character as ,pemba2 its    
outer shore is fringed1 and its southern
 extremity is connected with  ,keelwa   
,point on the mainland by a chain of    
islands fringed by reefs2  coloured red4
 ,the four last-mentioned islands       
resemble in many respects  some of the  
islands in the ,red ,sea1 which will    
presently be described4--  ,keelwa4 ,in 
a plan of the shore1 a space of twenty  
miles ,n4 and ,s4 of  this place is     
fringed by reefs1 apparently of coral3  
these reefs are  prolonged still further
 southward in ,owen's general chart4    
,the coast in  the plans of the rivers  
,lindy and ,monghow 7#i #ei and #aj #g  
,s47  has the same structure2 coloured  
red4--,querimba ,islands 7from #aj #dj  
to #ac ,s474 ,a chart on a large scale  
is given of these islands2 they  are    
low1 and of coral-formation 7,boteler's 
8,narr40 volume ii41 page  #ed72 and    
generally have extensive reefs          
projecting from them which are  dry at  

low water1 and which on the outside rise
 abruptly from a deep  sea3 on their    
insides they are separated from the     
continent by a  channel1 or rather a    
succession of bays1 with an average     
depth of ten  fathoms4 ,the small       
headlands on the continent also have    
coral-banks  attached to them2 and the  
,querimba islands and banks are placed  
on the  lines of prolongation of these  
headlands1 and are separated from them  
by very shallow channels4 ,it is evident
 that whatever cause1 whether  the      
drifting of sediment or subterranean    
movements1 produced the  headlands1     
likewise produced1 as might have been   
expected1 submarine  prolongations to   
them2 and these towards their outer     
extremities1 have  since afforded a     
favourable basis for the growth of      
coral-reefs1 and  subsequently for the  
formation of islets4 ,as these reefs    
clearly belong  to the fringing class1  
the ,querimba islands have been coloured
  red4--,monabila 7#ac #cb ,s474 ,in the

 plan of this harbour1 the  headlands   
outside are fringed by reefs apparently 
of coral2 coloured  red4--,mozambique   
7#aej ,s47 ,the outer part of the island
 on which the  city is built1 and the   
neighbouring islands1 are fringed by    
coral-reefs2 coloured red4 ,from the    
description given in ,owen's 8,narr40   
7volume i41 page #afb71 the shore from  
,mozambique to ,delagoa ,bay  appears to
 be low and sandy2 many of the shoals   
and islets off this  line of coast are  
of coral-formation2 but from their small
 size and  lowness1 it is not possible1 
from the charts1 to know whether they   
are  truly fringed4 ,hence this portion 
of coast is left uncoloured1 as are     
likewise those parts more northward1 of 
which no mention has been made  in the  
foregoing pages from the want of        
information4    ,,persian ,,gulf4--,from
 the charts lately published on a large 
scale by the  ,east ,india ,company1 it 
appears that several parts1 especially  
the  southern shores of this gulf1 are  

fringed by coral-reefs2 but as the      
water is very shallow1 and as there are 
numerous sandbanks1 which are  difficult
 to distinguish on the chart from reefs1
 ,i have not coloured  the upper part   
red4 ,towards the mouth1 however1 where 
the water is  rather deeper1 the islands
 of ,ormuz and ,larrack1 appear so      
regularly fringed1 that ,i have coloured
 them red4 ,there are certainly  no     
atolls in the ,persian ,gulf4 ,the      
shores of ,immaum1 and of the           
promontory forming the southern headland
 of the ,persian ,gulf1 seem to  be     
without reefs4 ,the whole ,s4,w4 part   
7except one or two small patches7  of   
,arabia ,felix1 and the shores of       
,socotra appear from the charts  and    
memoir of ,captain ,haines              
78,geographical ,journal10 #ahci1 page  
#abe7  to be without any reefs4 ,i      
believe there are no extensive          
coral-reefs  on any part of the coasts  
of ,india1 except on the low promontory 
of  ,madura 7as already mentioned7 in   

front of ,ceylon4    ,,red ,,sea4--,my  
information is chiefly derived from the 
admirable charts  published by the ,east
 ,india ,company in #ahcf1 from personal
  communication with ,captain ,moresby1 
one of the surveyors1 and from the      
excellent memoir1 8ber die ,natur der   
,corallen-,bnken des ,rothen  ,meeres10 
by ,ehrenberg4 ,the plains immediately  
bordering the ,red ,sea  seem chiefly to
 consist of a sedimentary formation of  
the newer  tertiary period4 ,the shore  
is1 with the exception of a few parts1  
fringed by coral-reefs4 ,the water is   
generally profoundly deep close to  the 
shore2 but this fact1 which has         
attracted the attention of most         
voyagers1 seems to have no necessary    
connection with the presence of  reefs2 
for ,captain ,moresby particularly      
observed to me1 that1 in  latitude #bd  
#aj on the eastern side1 there is a     
piece of coast1 with  very deep water   
close to it1 without any reefs1 but not 
differing in  other respects from the   

usual nature of the coast-line4 ,the    
most  remarkable feature in the ,red    
,sea is the chain of submerged banks1   
reefs1 and islands1 lying some way from 
the shore1 chiefly on the  eastern side2
 the space within being deep enough to  
admit a safe  navigation in small       
vessels4 ,the banks are generally of an 
oval form1  and some miles in width2 but
 some of them are very long in          
proportion  to their width4 ,captain    
,moresby informs me that any one1 who   
had not  made actual plans of them1     
would be apt to think that they were    
much  more elongated than they really   
are4 ,many of them rise to the surface1 
but the greater number lie from five to 
thirty fathoms beneath it1 with         
irregular soundings on them4 ,they      
consist of sand and living coral2  coral
 on most of them1 according to ,captain 
,moresby1 covering the  greater part of 
their surface4 ,they extend parallel to 
the shore1 and  they are not            
unfrequently connected in their middle  

parts by short  transverse banks with   
the mainland4 ,the sea is generally     
profoundly  deep quite close to them1 as
 it is near most parts of the coast of  
the  mainland2 but this is not          
universally the case1 for between       
latitude  #ae and #ag the water deepens 
quite gradually from the banks1 both on 
the eastern and western shores1 towards 
the middle of the sea4 ,islands  in many
 parts arise from these banks2 they are 
low1 flat-topped1 and  consist of the   
same horizontally stratified formation  
with that forming  the plain-like margin
 of the mainland4 ,some of the smaller  
and lower  islands consist of mere sand4
 ,captain ,moresby informs me1 that     
small  masses of rock1 the remnants of  
islands1 are left on many banks where   
there is now no dry land4 ,ehrenberg    
also asserts that most of the  islets1  
even the lowest1 have a flat abraded    
basis1 composed of the  same tertiary   
formation3 he believes that as soon as  
the surf wears  down the protuberant    

parts of a bank1 just beneath the level 
of the  sea1 the surface becomes        
protected from further abrasion by the  
growth  of coral1 and he thus accounts  
for the existence of so many banks      
standing on a level with the surface of 
this sea4 ,it appears that most  of the 
islands are certainly decreasing in     
size4    ,the form of the banks and     
islands is most singular in the part    
just  referred to1 namely1 from latitude
 #ae to #ag1 where the sea deepens      
quite gradually3 the ,dhalac group1 on  
the western coast1 is  surrounded by an 
intricate archipelago of islets and     
shoals2 the main  island is very        
irregularly shaped1 and it includes a   
bay seven miles  long1 by four across1  
in which no bottom was found with #beb  
feet3 there  is only one entrance into  
this bay1 half a mile wide1 and with an 
island in front of it4 ,the submerged   
banks on the eastern coast1 within  the 
same latitudes1 round ,farsan ,island1  
are1 likewise1 penetrated by  many      

narrow creeks of deep water2 one is     
twelve miles long1 in the form  of a    
hatchet1 in which1 close to its broad   
upper end1 soundings were  not struck   
with #cfj feet1 and its entrance is only
 half a mile wide3 in  another creek of 
the same nature1 but even with a more   
irregular  outline1 there was no bottom 
with #dhj feet4 ,the island of ,farsan1 
itself1 has as singular a form as any of
 its surrounding banks4 ,the  bottom of 
the sea round the ,dhalac and ,farsan   
,islands consists chiefly  of sand and  
agglutinated fragments1 but1 in the deep
 and narrow creeks1  it consists of mud2
 the islands themselves consist of thin1
  horizontally stratified1 modern       
tertiary beds1 containing but little    
broken coral2#b their shores are fringed
 by living coral-reefs4     #b ,rppell1 
8,reise in ,abyssinie10 ,band4 i41 ,s4  
#bdg4      ,from the account given by   
,rppell#c of the manner in which ,dhalac
 has  been rent by fissures1 the        
opposite sides of which have been       

unequally  elevated 7in one instance to 
the amount of fifty feet71 it seems     
probable that its irregular form1 as    
well as probably that of ,farsan1  may  
have been partly caused by unequal      
elevations2 but1 considering the        
general form of the banks1 and of the   
deep-water creeks1 together with  the   
composition of the land1 ,i think their 
configuration is more  probably due in  
great part to strong currents having    
drifted sediment  over an uneven bottom3
 it is almost certain that their form   
cannot be  attributed to the growth of  
coral4 ,whatever may have been the      
precise  origin of the ,dhalac and      
,farsan ,archipelagoes1 the greater     
number of  the banks on the eastern side
 of the ,red ,sea seem to have          
originated  through nearly similar      
means4 ,i judge of this from their      
similarity in  configuration 7in proof  
of which ,i may instance a bank on the  
east  coast in latitude #bb2 and        
although it is true that the northern   

banks  generally have a less complicated
 outline71 and from their similarity  in
 composition1 as may be observed in     
their upraised portions4 ,the  depth    
within the banks northward of latitude  
#ag1 is usually greater1  and their     
outer sides shelve more abruptly        
7circumstances which seem to  go        
together7 than in the ,dhalac and       
,farsan ,archipelagoes2 but this  might 
easily have been caused by a difference 
in the action of the  currents during   
their formation3 moreover1 the greater  
quantity of  living coral1 which1       
according to ,captain ,moresby1 exists  
on the  northern banks1 would tend to   
give them steeper margins4     #c       
,rppell1 8,reise in ,abyssinie10 ,band4 
i41 ,s4 #bde4      ,from this account1  
brief and imperfect as it is1 we can see
 that the  great chain of banks on the  
eastern coast1 and on the western side  
in  the southern portion1 differ greatly
 from true barrier-reefs wholly  formed 
by the growth of coral4 ,it is indeed   

the direct conclusion of  ,ehrenberg    
78,uber die10 etc41 pages #de and #ea71 
that they are connected  in their origin
 quite secondarily with the growth of   
coral2 and he  remarks that the islands 
off the coast of ,norway1 if worn down  
level  with the sea1 and merely coated  
with living coral1 would present a      
nearly similar appearance4 ,i cannot1   
however1 avoid suspecting1 from         
information given me by ,dr4 ,malcolmson
 and ,captain ,moresby1 that  ,ehrenberg
 has rather under-rated the influence of
 corals1 in some  places at least1 on   
the formation of the tertiary deposits  
of the ,red  ,sea4    ,the ,west ,coast 
of the ,red ,sea between lat4 #ai and   
#bb4--,there are1  in this space1 reefs1
 which1 if ,i had known nothing of those
 in other  parts of the ,red ,sea1 ,i   
should unhesitatingly have considered as
  barrier-reefs2 and1 after             
deliberation1 ,i have come to the same  
conclusion4 ,one of these reefs1 in #bj 
#ae1 is twenty miles long1 less  than a 

mile in width 7but expanding at the     
northern end into a disc71  slightly    
sinuous1 and extending parallel to the  
mainland at the  distance of five miles 
from it1 with very deep water within2 in
 one  spot soundings were not obtained  
with #bje fathoms4 ,some leagues further
  south1 there is another linear reef1  
very narrow1 ten miles long1 with  other
 small portions of reef1 north and      
south1 almost connected with  it2 and   
within this line of reefs 7as well as   
outside7 the water is  profoundly deep4 
,there are also some small linear and   
sickle-formed  reefs1 lying a little way
 out at sea4 ,all these reefs are       
covered1 as ,i  am informed by ,captain 
,moresby1 by living corals4 ,here1 then1
 we have  all the characters of reefs of
 the barrier class2 and in some outlying
  reefs we have an approach to the      
structure of atolls4 ,the source of my  
doubts about the classification of these
 reefs1 arises from having  observed in 
the ,dhalac and ,farsan groups the      

narrowness and  straightness of several 
spits of sand and rock3 one of these    
spits in  the ,dhalac group is nearly   
fifteen miles long1 only two broad1 and 
it  is bordered on each side with deep  
water2 so that1 if worn down by the     
surf1 and coated with living corals1 it 
would form a reef nearly  similar to    
those within the space under            
consideration4 ,there is1 also1  in this
 space 7latitude #ba7 a peninsula1      
bordered by cliffs1 with its  extremity 
worn down to the level of the sea1 and  
its basis fringed with  reefs3 in the   
line of prolongation of this peninsula1 
there lies the  island of ,macowa       
7formed1 according to ,captain ,moresby1
 of the usual  tertiary deposit71 and   
some smaller islands1 large parts of    
which  likewise appear to have been worn
 down1 and are now coated with living   
corals4 ,if the removal of the strata in
 these several cases had been  more     
complete1 the reefs thus formed would   
have nearly resembled those             

barrier-like ones now under discussion4 
,notwithstanding these facts1 ,i  cannot
 persuade myself that the many very     
small1 isolated1 and  sickle-formed     
reefs and others1 long1 nearly straight1
 and very narrow1  with the water       
unfathomably deep close round them1     
could possibly have  been formed by     
corals merely coating banks of sediment1
 or the abraded  surfaces of irregularly
 shaped islands4 ,i feel compelled to   
believe  that the foundations of these  
reefs have subsided1 and that the       
corals1  during their upward growth1    
have given to these reefs their present 
forms3 ,i may remark that the subsidence
 of narrow and  irregularly-shaped      
peninsulas and islands1 such as those   
existing on  the coasts of the ,red     
,sea1 would afford the requisite        
foundations for  the reefs in question4 
,the ,west ,coast from lat4 #bb to      
#bd4--,this part of the coast 7north  of
 the space coloured blue on the map7 is 
fronted by an irregularly  shelving     

bank1 from about ten to thirty fathoms  
deep2 numerous little  reefs1 some of   
which have the most singular shapes1    
rise from this  bank4 ,it may be        
observed1 respecting one of them1 in    
latitude #bc #aj1  that if the          
promontory in latitude #bd were worn    
down to the level of  the sea1 and      
coated with corals1 a very similar and  
grotesquely formed  reef would be       
produced4 ,many of the reefs on this    
part of the coast may  thus have        
originated2 but there are some sickle1  
and almost  atoll-formed reefs lying in 
deep water off the promontory in        
latitude  #bd1 which lead me to suppose 
that all these reefs are more probably  
allied to the barrier or atoll classes4 
,i have not1 however1 ventured  to      
colour this portion of coast4--,on the  
west coast from lat4 #ai to  #ag 7south 
of space coloured blue on the map71     
there are many low  islets of very small
 dimensions1 not much elongated1 and    
rising out of  great depths at a        

distance from the coast2 these cannot be
 classed  either with atolls1 or        
barrier- or fringing-reefs4 ,i may here 
remark  that the outlying reefs on the  
west coast1 between latitude #ai and    
#bd1 are the only ones in the ,red ,sea1
 which approach in structure to  the    
true atolls of the ,indian and ,pacific 
,oceans1 but they present only          
imperfect miniature likenesses of them4 
,eastern ,coast4--,i have felt the      
greatest doubt about colouring any      
portion of this coast1 north of the     
fringing-reefs round the ,farsan        
,islands in #af #aj4 ,there are many    
small outlying coral-reefs along the    
whole line of coast2 but as the greater 
number rise from banks not very  deeply 
submerged 7the formation of which has   
been shown to be only  secondarily      
connected with the growth of coral71    
their origin may be  due simply to the  
growth of knolls of corals1 from an     
irregular  foundation situated within a 
limited depth4 ,but between latitude #ah

  and #bj1 there are so many linear1    
elliptic1 and extremely small reefs1    
rising abruptly out of profound depths1 
that the same reasons1 which  led me to 
colour blue a portion of the west coast1
 have induced me to  do the same in this
 part4 ,there exist some small outlying 
reefs rising  from deep water1 north of 
latitude #bj 7the northern limit        
coloured  blue71 on the east coast2 but 
as they are not very numerous and       
scarcely any of them linear1 ,i have    
thought it right to leave them          
uncoloured4    ,in the southern parts of
 the ,red ,sea1 considerable spaces of  
the  mainland1 and of some of the       
,dhalac islands1 are skirted by reefs1  
which1 as ,i am informed by ,captain    
,moresby1 are of living coral1 and  have
 all the characters of the fringing     
class4 ,as in these latitudes1  there   
are no outlying linear or sickle-formed 
reefs1 rising out of  unfathomable      
depths1 ,i have coloured these parts of 
the coast red4 ,on  similar grounds1 ,i 

have coloured red the northern parts of 
the western  coast 7north of latitude   
#bd #cj71 and likewise the shores of the
  chief part of the ,gulf of ,suez4 ,in 
the ,gulf of ,acaba1 as ,i am  informed 
by ,captain ,moresby there are no       
coral-reefs1 and the water is           
profoundly deep4    ,,west              
,,indies4--,my information regarding the
 reefs of this area1 is  derived from   
various sources1 and from an examination
 of numerous  charts2 especially of     
those lately executed during the survey 
under  ,captain ,owen1 ,r4,n4 ,i lay    
under particular obligation to ,captain 
,bird  ,allen1 ,r4,n41 one of the       
members of the late survey1 for many    
personal  communications on this        
subject4 ,as in the case of the ,red    
,sea1 it is  necessary to make some     
preliminary remarks on the submerged    
banks of  the ,west ,indies1 which are  
in some degree connected with           
coral-reefs1  and cause considerable    
doubts in their classification4 ,that   

large  accumulations of sediment are in 
progress on the ,west ,indian shores1   
will be evident to any one who examines 
the charts of that sea1  especially of  
the portion north of a line joining     
,yucutan and ,florida4  ,the area of    
deposition seems less intimately        
connected with the  debouchement of the 
great rivers1 than with the course of   
the  sea-currents2 as is evident from   
the vast extension of the banks from    
the promontories of ,yucutan and        
,mosquito4    ,besides the coast-banks1 
there are many of various dimensions    
which  stand quite isolated2 these      
closely resemble each other1 they lie   
from  two or three to twenty or thirty  
fathoms under water1 and are composed   
of sand1 sometimes firmly agglutinated1 
with little or no coral2 their  surfaces
 are smooth and nearly level1 shelving  
only to the amount of a  few fathoms1   
very gradually all round towards their  
edges1 where they  plunge abruptly into 
the unfathomable sea4 ,this steep       

inclination of  their sides1 which is   
likewise characteristic of the          
coast-banks1 is  very remarkable3 ,i may
 give as an instance1 the ,misteriosa   
,bank1 on the  edges of which the       
soundings change in #bej fathoms        
horizontal distance1  from #aa to #baj  
fathoms2 off the northern point of the  
bank of ,old  ,providence1 in #bjj      
fathoms horizontal distance1 the change 
is from #ai  to #aeb fathoms2 off the   
,great ,bahama ,bank1 in #afj fathoms   
horizontal  distance1 the inclination is
 in many places from #aj fathoms to no  
bottom with #aij fathoms4 ,on coasts in 
all parts of the world1 where  sediment 
is accumulating1 something of this kind 
may be observed2 the  banks shelve very 
gently far out to sea1 and then         
terminate abruptly4  ,the form and      
composition of the banks standing in the
 middle parts of  the ,w4 ,indian ,sea1 
clearly show that their origin must be  
chiefly  attributed to the accumulation 
of sediment2 and the only obvious       

explanation of their isolated position  
is the presence of a nucleus1  round    
which the currents have collected fine  
drift matter4 ,any one who  will compare
 the character of the bank surrounding  
the hilly island of  ,old ,providence1  
with those banks in its neighbourhood   
which stand  isolated1 will scarcely    
doubt that they surround submerged      
mountains4  ,we are led to the same     
conclusion by examining the bank called 
,thunder  ,knoll1 which is separated    
from the ,great ,mosquito ,bank by a    
channel  only seven miles wide1 and #ade
 fathoms deep4 ,there cannot be any     
doubt  that the ,mosquito ,bank has been
 formed by the accumulation of sediment 
round the promontory of the same name2  
and ,thunder ,knoll resembles the       
,mosquito ,bank1 in the state of its    
surface submerged twenty fathoms1 in    
the inclinations of its sides1 in       
composition1 and in every other         
respect4 ,i may observe1 although the   
remark is here irrelevant1 that         

geologists should be cautious in        
concluding that all the outlyers of  any
 formation have once been connected     
together1 for we here see that          
deposits1 doubtless of exactly the same 
nature1 may be deposited with  large    
valley-like spaces between them4        
,linear strips of coral-reefs and small 
knolls project from many of the         
isolated1 as well as coast-banks2       
sometimes they occur quite  irregularly 
placed1 as on the ,mosquito ,bank1 but  
more generally they  form crescents on  
the windward side1 situated some little 
distance  within the outer edge of the  
banks3--thus on the ,serranilla ,bank   
they  form an interrupted chain which   
ranges between two and three miles      
within the windward margin3 generally   
they occur1 as on ,roncador1  ,courtown1
 and ,anegada ,banks1 nearer the line of
 deep water4 ,their  occurrence on the  
windward side is conformable to the     
general rule1 of  the efficient kinds of
 corals flourishing best where most     

exposed2 but  their position some way   
within the line of deep water ,i cannot 
explain1  without it be1 that a depth   
somewhat less than that close to the    
outer  margin of the banks1 is most     
favourable to their growth4 ,where the  
corals have formed a nearly continuous  
rim1 close to the windward edge  of a   
bank some fathoms submerged1 the reef   
closely resembles an atoll2  but if the 
bank surrounds an island 7as in the case
 of ,old ,providence71  the reef        
resembles an encircling barrier-reef4 ,i
 should undoubtedly  have classed some  
of these fringed banks as imperfect     
atolls1 or  barrier-reefs1 if the       
sedimentary nature of their foundations 
had not  been evident from the presence 
of other neighbouring banks1 of similar 
forms and of similar composition1 but   
without the crescent-like  marginal     
reef3 in the third chapter1 ,i observed 
that probably some  atoll-like reefs did
 exist1 which had originated in the     
manner here  supposed4    ,proofs of    

elevation within recent tertiary periods
 abound1 as referred  to in the sixth   
chapter1 over nearly the whole area of  
the ,west ,indies4  ,hence it is easy to
 understand the origin of the low land  
on the  coasts1 where sediment is now   
accumulating2 for instance on the       
northern part of ,yucutan1 and on the   
,n4,e4 part of ,mosquito1 where the     
land is low1 and where extensive banks  
appear to be in progressive  formation4 
,hence1 also1 the origin of the ,great  
,bahama ,banks1 which are  bordered on  
their western and southern edges by very
 narrow1 long1  singularly shaped       
islands1 formed of sand1 shells1 and    
coral-rock1 and  some of them about a   
hundred feet in height1 is easily       
explained by the  elevation of banks    
fringed on their windward 7western and  
southern7  sides by coral-reefs4 ,on    
this view1 however1 we must suppose     
either  that the chief part of the      
surfaces of the great ,bahama sandbanks 
were  all originally deeply submerged1  

and were brought up to their present    
level by the same elevatory action1     
which formed the linear islands2 or     
that during the elevation of the banks1 
the superficial currents and  swell of  
the waves continued wearing them down   
and keeping them at a  nearly uniform   
level3 the level is not quite uniform2  
for1 in  proceeding from the ,n4,w4 end 
of the ,bahama group towards the ,s4,e4 
end1  the depth of the banks increases1 
and the area of land decreases1 in a    
very gradual and remarkable manner4 ,the
 latter view1 namely1 that these  banks 
have been worn down by the currents and 
swell during their  elevation1 seems to 
me the most probable one4 ,it is1 also1 
,i believe1  applicable to many banks1  
situated in widely distant parts of the 
,west  ,indian ,sea1 which are wholly   
submerged2 for1 on any other view1 we   
must  suppose1 that the elevatory forces
 have acted with astonishing            
uniformity4    ,the shore of the ,gulf  
of ,mexico1 for the space of many       

hundred miles1  is formed by a chain of 
lagoons1 from one to twenty miles in    
breadth  78,columbian ,navigator10 page 
#agh1 etc471 containing either fresh or 
salt water1 and separated from the sea  
by linear strips of sand4 ,great  spaces
 of the shores of ,southern ,brazil4#d  
and of the ,united ,states  from ,long  
,island 7as observed by ,professor      
,rogers7 to ,florida have the  same     
character4 ,professor ,rogers1 in his   
8,report to the ,british  ,association0 
7volume iii41 page #ac71 speculates on  
the origin of these  low1 sandy1 linear 
islets2 he states that the layers of    
which they are  composed are too        
homogeneous1 and contain too large a    
proportion of  shells1 to permit the    
common supposition of their formation   
being  simply due to matter thrown up1  
where it now lies1 by the surf3 he      
considers these islands as upheaved bars
 or shoals1 which were  deposited in    
lines where opposed currents met4 ,it is
 evident that these  islands and spits  

of sand parallel to the coast1 and      
separated from it  by shallow lagoons1  
have no necessary connection with       
coral-formations4  ,but in ,southern    
,florida1 from the accounts ,i have     
received from persons  who have resided 
there1 the upraised islands seem to be  
formed of  strata1 containing a good    
deal of coral1 and they are extensively 
fringed by living reefs2 the channels   
within these islands are in some  places
 between two and three miles wide1 and  
five or six fathoms deep1  though       
generally#e they are less in depth than 
width4 ,after having  seen how          
frequently banks of sediment in the     
,west ,indian ,sea are  fringed by      
reefs1 we can readily conceive that bars
 of sediment might  be greatly aided in 
their formation along a line of coast1  
by the  growth of corals2 and such bars 
would1 in that case1 have a deceptive   
resemblance with true barrier-reefs4    
#d ,in the 8,london and ,edinburgh      
,philosophical ,journal10 #ahda1 page   

#beg1 ,i have described a singular bar  
of sandstone lying parallel to   the    
coast off ,pernambuco in ,brazil1 which 
probably is an analogous   formation4   
#e ,in the ordinary sea-charts1 no      
lagoons appear on the coast of          
,florida1 north of #bf2 but ,major      
,whiting 78,silliman's ,journal10 volume
   xxxv41 page #ed7 says that many are  
formed by sand thrown up along the      
whole line of coast from ,st4           
,augustine's to ,jupiter ,inlet4        
,having now endeavoured to remove some  
sources of doubt in classifying  the    
reefs of the ,west ,indies1 ,i will give
 my authorities for colouring  such     
portions of the coast as ,i have thought
 myself warranted in doing4  ,captain   
,bird ,allen informs me1 that most of   
the islands on the ,bahama  ,banks are  
fringed1 especially on their windward   
sides1 with living  reefs2 and hence ,i 
have coloured those1 which are thus     
represented in  ,captain ,owen's late   
chart1 red4 ,the same officer informs   

me1 that the  islands along the southern
 part of ,florida are similarly fringed2
  coloured red4 ,,cuba3 ,proceeding     
along the northern coast1 at the        
distance of forty miles from the extreme
 ,s4,e4 point1 the shores are  fringed  
by reefs1 which extend westward for a   
space of #afj miles1 with  only a few   
breaks4 ,parts of these reefs are       
represented in the plans of  the        
harbours on this coast by ,captain      
,owen2 and an excellent  description is 
given of them by ,mr4 ,taylor 7,loudon's
 8,mag4 of ,nat4  ,hist40 volume ix41   
page #ddi72 he states that they enclosed
 a space  called the 8baxo10 from half  
to three-quarters of a mile in width1   
with a sandy bottom1 and a little coral4
 ,in most parts people can wade1  at low
 water1 to the reef2 but in some parts  
the depth is between two  and three     
fathoms4 ,close outside the reef1 the   
depth is between six and  seven fathoms2
 these well-characterised fringing-reefs
 are coloured  red4 ,westward of        

longitude #gg #cj1 on the northern side 
of ,cuba1 a  great bank commences1 which
 extends along the coast for nearly four
  degrees of longitude4 ,in the place of
 its commencement1 in its  structure1   
and in the 8cays10 or low islands on its
 edge1 there is a  marked correspondence
 7as observed by ,humboldt1 8,pers4     
,narr40 volume  vii41 page #hh7 between 
it and the ,great ,bahama and ,sal      
,banks1 which lie  directly in front4   
,hence one is led to attribute the same 
origin to  both these sets of banks2    
namely1 the accumulation of sediment1   
conjoined with an elevatory movement1   
and the growth of coral on their        
outward edges2 those parts which appear 
fringed by living reefs are  coloured   
red4 ,westward of these banks1 there is 
a portion of coast  apparently without  
reefs1 except in the harbours1 the      
shores of which  seem in the published  
plans to be fringed4 ,the ,colorado     
,shoals 7see  ,captain ,owen's charts71 
and the low land at the western end of  

,cuba1  correspond as closely in        
relative position and structure to the  
banks  at the extreme point of ,florida1
 as the banks above described on the    
north side of ,cuba1 do to the ,bahamas1
 the depth within the islets and  reefs 
on the outer edge of the ,colorados1 is 
generally between two  and three        
fathoms1 increasing to twelve fathoms in
 the southern part1  where the bank     
becomes nearly open1 without islets or  
coral-reefs2 the  portions which are    
fringed are coloured red4 ,the southern 
shore of ,cuba  is deeply concave1 and  
the included space is filled up with mud
 and  sandbanks1 low islands and        
coral-reefs4 ,between the mountainous   
,isle  of ,pines and the southern shore 
of ,cuba1 the general depth is only     
between two and three fathoms2 and in   
this part small islands1 formed  of     
fragmentary rock and broken madrepores  
7,humboldt1 8,pers4 ,narr40  volume vii4
 pages #ea1 #hf to #ij1 #bia1 #cji1     
#cbj71 rise abruptly1 and just  reach   

the surface of the sea4 ,from some      
expressions used in the  8,columbian    
,navigator0 7volume i41 part ii41 page  
#id71 it appears that  considerable     
spaces along the outer coast of         
,southern ,cuba are bounded  by cliffs  
of coral-rock1 formed probably by the   
upheaval of coral-reefs  and sandbanks4 
,the charts represent the southern part 
of the ,isle of  ,pines as fringed by   
reefs1 which the 8,columb4 ,navig40 says
 extend some  way from the coast1 but   
have only from nine to twelve feet water
 on  them2 these are coloured red4--,i  
have not been able to procure any       
detailed description of the large groups
 of banks and 8cays0 further  eastward  
on the southern side of ,cuba2 within   
them there is a large  expanse1 with a  
muddy bottom1 from eight to twelve      
fathoms deep2  although some parts of   
this line of coast are represented in   
the  general charts of the ,west        
,indies1 as fringed1 ,i have not thought
 it  prudent to colour them4 ,the       

remaining portion of the south coast of 
,cuba appears to be without coral-reefs4
    ,,yucutan4--,the ,n4,e4 part of the 
promontory appears in ,captain ,owen's  
charts to be fringed2 coloured red4 ,the
 eastern coast1 from #bj to #ah  is     
fringed4 ,south of latitude #ah1 there  
commences the most remarkable  reef in  
the ,west ,indies3 it is about one      
hundred and thirty miles in  length1    
ranging in a ,n4 and ,s4 line1 at an    
average distance of fifteen  miles from 
the coast4 ,the islets on it are all    
low1 as ,i have been  informed by       
,captain ,b4 ,allen2 the water deepens  
suddenly on the outside  of the reef1   
but not more abruptly than off many of  
the sedimentary  banks3 within its      
southern extremity 7off ,honduras7 the  
depth is  twenty-five fathoms2 but in   
the more northern parts1 the depth soon 
increases to ten fathoms1 and within the
 northernmost part1 for a space  of     
twenty miles1 the depth is only from one
 to two fathoms4 ,in most of  these     

respects we have the characteristics of 
a barrier-reef2  nevertheless1 from     
observing1 first1 that the channel      
within the reef  is a continuation of a 
great irregular bay1 which penetrates   
the  mainland to the depth of fifty     
miles2 and secondly1 that considerable  
spaces of this barrier-like reef are    
described in the charts 7for  instance1 
in latitude #af #de and #af #ab7 as     
formed of pure sand2 and  thirdly1 from 
knowing that sediment is accumulating in
 many parts of  the ,west ,indies in    
banks parallel to the shore2 ,i have not
 ventured to  colour this reef as a     
barrier1 without further evidence that  
it has  really been formed by the growth
 of corals1 and that it is not merely   
in parts a spit of sand1 and in other   
parts a worn down promontory1  partially
 coated and fringed by reefs2 ,i lean1  
however1 to the  probability of its     
being a barrier-reef1 produced by       
subsidence4 ,to add  to my doubts1      
immediately on the outside of this      

barrier-like reef1  ,turneffe1          
,lighthouse1 and ,glover reefs are      
situated1 and these  reefs have so      
completely the form of atolls1 that if  
they had occurred  in the ,pacific1 ,i  
should not have hesitated about         
colouring them blue4  turneffe ,reef    
seems almost entirely filled up with low
 mud islets2  and the depth within the  
other two reefs is only from one to     
three  fathoms4 ,from this circumstance 
and from their similarity in form1      
structure1 and relative position1 both  
to the bank called ,northern            
,triangles1 on which there is an islet  
between seventy and eighty feet1  and to
 ,cozumel ,island1 the level surface of 
which is likewise between  seventy and  
eighty feet in height1 ,i consider it   
more probable that the  three foregoing 
banks are the worn down bases of        
upheaved shoals1  fringed with corals1  
than that they are true atolls1 wholly  
produced by  the growth of coral during 
subsidence2 left uncoloured4    ,in     

front of the eastern ,mosquito coast1   
there are between latitude  #ab and #af 
some extensive banks 7already mentioned1
 page #adh71 with  high islands rising  
from their centres2 and there are other 
banks  wholly submerged1 both of which  
kinds of banks are bordered1 near their 
windward margins1 by crescent-shaped    
coral-reefs4 ,but it can hardly be      
doubted1 as was observed in the         
preliminary remarks1 that these banks   
owe their origin1 like the great bank   
extending from the ,mosquito            
promontory1 almost entirely to the      
accumulation of sediment1 and not to    
the growth of corals2 hence ,i have not 
coloured them4    ,cayman ,island3 this 
island appears in the charts to be      
fringed2 and  ,captain ,b4 ,allen       
informs me that the reefs extend about a
 mile from the  shore1 and have only    
from five to twelve feet water within   
them2  coloured red4--,jamaica3 judging 
from the charts1 about fifteen miles  of
 the ,s4,e4 extremity1 and about twice  

that length on the ,s4,w4  extremity1   
and some portions on the ,s4 side near  
,kingston and ,port  ,royal1 are        
regularly fringed1 and therefore are    
coloured red4 ,from the  plans of some  
harbours on the ,n4 side of ,jamaica1   
parts of the coast  appear to be        
fringed2 but as these are not           
represented in the charts of  the whole 
island1 ,i have not coloured them4--,st4
 ,domingo3 ,i have not  been able to    
obtain sufficient information1 either   
from plans of the  harbours1 or from    
general charts1 to enable me to colour  
any part of  the coast1 except sixty    
miles from ,port de ,plata westward1    
which seems  very regularly fringed2    
many other parts1 however1 of the coast 
are  probably fringed1 especially       
towards the eastern end of the          
island4--,puerto ,rico3 considerable    
portions of the southern1 western1  and 
eastern coasts1 and some parts of the   
northern coast1 appear in the  charts to
 be fringed2 coloured red4--,some miles 

in length of the  southern side of the  
,island of ,st1 ,thomas is fringed2 most
 of the  ,virgin ,gorda ,islands1 as ,i 
am informed by ,mr4 ,schomburgk1 are    
fringed2 the shores of ,anegada1 as well
 as the bank on which it  stands1 are   
likewise fringed2 these islands have    
been coloured red4 ,the  greater part of
 the southern side of ,santa ,cruz      
appears in the ,danish  survey to be    
fringed 7see also ,prof4 ,hovey's       
account of this island1 in  8,silliman's
 ,journal10 volume xxxv41 page #gd72 the
 reefs extend along  the shore for a    
considerable space1 and project rather  
more than a  mile2 the depth within the 
reef is three fathoms2 coloured         
red4--,the  ,antilles1 as remarked by   
,von ,buch 78,descrip4 ,iles ,canaries10
 page  #did71 may be divided into two   
linear groups1 the western row being    
volcanic1 and the eastern of modern     
calcareous origin2 my information  is   
very defective on the whole group4 ,of  
the eastern islands1 ,barbuda  and the  

western coasts of ,antigua and          
,mariagalante appear to be  fringed3    
this is also the case with ,barbadoes1  
as ,i have been  informed by a resident2
 these islands are coloured red4 ,on the
 shores  of the ,western ,antilles1 of  
volcanic origin1 very few coral-reefs   
appear to exist4 ,the island of         
,martinique1 of which there are         
beautifully executed ,french charts1 on 
a very large scale1 alone  presents any 
appearance worthy of special notice4    
,the south-western1  southern1 and      
eastern coasts1 together forming about  
half the  circumference of the island1  
are skirted by very irregular banks1    
projecting generally rather less than a 
mile from the shore1 and lying  from two
 to five fathoms submerged4 ,in front of
 almost every valley1  they are breached
 by narrow1 crooked1 steep-sided        
passages4 ,the ,french  engineers       
ascertained by boring1 that these       
submerged banks consisted  of           
madreporitic rocks1 which were covered  

in many parts by thin layers  of mud or 
sand4 ,from this fact1 and especially   
from the structure of  the narrow       
breaches1 ,i think there can be little  
doubt that these banks  once formed     
living reefs1 which fringed the shores  
of the island1 and  like other reefs    
probably reached the surface4 ,from some
 of these  submerged banks reefs of     
living coral rise abruptly1 either in   
small  detached patches1 or in lines    
parallel to1 but some way within the    
outer edges of the banks on which they  
are based4 ,besides the above  banks    
which skirt the shores of the island1   
there is on the eastern  side a range of
 linear banks1 similarly constituted1   
twenty miles in  length1 extending      
parallel to the coast line1 and         
separated from it by  a space between   
two and four miles in width1 and from   
five to fifteen  fathoms in depth4 ,from
 this range of detached banks1 some     
linear reefs  of living coral likewise  
rise abruptly2 and if they had been of  

greater  length 7for they do not front  
more than a sixth part of the           
circumference of the island71 they would
 necessarily from their  position have  
been coloured as barrier-reefs2 as the  
case stands they  are left uncoloured4  
,i suspect that after a small amount of 
subsidence1  the corals were killed by  
sand and mud being deposited on them1   
and the  reefs being thus prevented from
 growing upwards1 the banks of          
madreporitic rock were left in their    
present submerged condition4    ,,the   
,,bermuda ,,islands have been carefully 
described by ,lieutenant ,nelson1  in an
 excellent ,memoir in the 8,geological  
,transactions0 7volume v41  part i41    
page #ajc74 ,in the form of the bank or 
reef1 on one side of  which the islands 
stand1 there is a close general         
resemblance to an  atoll2 but in the    
following respects there is a           
considerable  difference1--first1 in the
 margin of the reef not forming 7as ,i  
have  been informed by ,mr4 ,chaffers1  

,r4,n47 a flat1 solid surface1 laid bare
  at low water1 and regularly bounding  
the internal space of shallow  water or 
lagoon2 secondly1 in the border of      
gradually shoaling water1  nearly a mile
 and a half in width1 which surrounds   
the entire outside  of the reef 7as is  
laid down in ,captain ,hurd's chart72   
and thirdly1 in  the size1 height1 and  
extraordinary form of the islands1 which
 present  little resemblance to the     
long1 narrow1 simple islets1 seldom     
exceeding  half a mile in breadth1 which
 surmount the annular reefs of almost   
all  the atolls in the ,indian and      
,pacific ,oceans4 ,moreover1 there are  
evident proofs 7,nelson1 ,ibid41 page   
#aah71 that islands similar to the      
existing ones1 formerly extended over   
other parts of the reef4 ,it  would1 ,i 
believe1 be difficult to find a true    
atoll with land exceeding  thirty feet  
in height2 whereas1 ,mr4 ,nelson        
estimates the highest point  of the     
,bermuda ,islands to be #bfj feet2 if1  

however1 ,mr4 ,nelson's view1  that the 
whole of the land consists of sand      
drifted by the winds1 and  agglutinated 
together1 were proved correct1 this     
difference would be  immaterial2 but1   
from his own account 7page #aah71 there 
occur in one  place1 five or six layers 
of red earth1 interstratified with the  
ordinary calcareous rock1 and including 
stones too heavy for the wind  to have  
moved1 without having at the same time  
utterly dispersed every  grain of the   
accompanying drifted matter4 ,mr4       
,nelson attributes the  origin of these 
several layers1 with their embedded     
stones1 to as many  violent             
catastrophes2 but further investigation 
in such cases has  generally succeeded  
in explaining phenomena of this kind by 
ordinary  and simpler means4 ,finally1  
,i may remark1 that these islands have a
  considerable resemblance in shape to  
,barbuda in the ,west ,indies1 and to   
,pemba on the eastern coast of ,africa1 
which latter island is about two        

hundred feet in height1 and consists of 
coral-rock4 ,i believe that the         
,bermuda ,islands1 from being fringed by
 living reefs1 ought to have been       
coloured red2 but ,i have left them     
uncoloured1 on account of their  general
 resemblance in external form to a      
lagoon-island or atoll4                 
,,index4      ,the names not in capitals
 are all names of places1 and refer     
exclusively to the ,appendix3 in        
well-defined archipelagoes1 or groups   
of islands1 the name of each separate   
island is not given4    ,,abrolhos1     
,brazil1 coated by corals4    ,abrolhos 
7,australia74    ,,absence of           
coral-reefs from certain coasts4        
,acaba1 gulf of4    ,admiralty group4   
,,africa1 east coast1 fringing-reef of4 
,madreporitic rock of4    ,africa1 east 
coast4    ,,age of individual corals4   
,aiou4    ,aitutaki4    ,aldabra4       
,alert reef4    ,alexander1 ,grand      
,duke1 island4    ,,allan1 ,dr41 on     
,holuthuri feeding on corals4 ,on quick 

growth of corals  at ,madagascar4 ,on   
reefs affected by currents4             
,alloufatou4    ,alphonse4              
,amargoura4 7,amargura47    ,amboina4   
,america1 west coast4    ,amirantes4    
,anachorites4    ,anambas4              
,,anamouka1 description of4             
,anamouka4    ,anadaman islands4        
,antilles4    ,appoo reef4    ,arabia   
,felix4    ,,areas1 great extent of1    
interspersed with low islands4 ,of      
subsidence  and of elevation4 ,of       
subsidence appear to be elongated4 ,of  
subsidence  alternating with areas of   
elevation4    ,arru group4              
,arzobispo4    ,,ascidia1 depth at which
 found4    ,assomption4    ,astova4     
,atlantic islands4    ,,atolls1 breaches
 in their reefs4 ,dimensions of4        
,dimensions of groups  of4 ,not based on
 craters or on banks of sediment1 or of 
rock4 ,of  irregular forms4 ,steepness  
of their flanks4 ,width of their reef   
and  islets4 ,their lowness4 ,lagoons4  
,general range4 ,with part of their reef

  submerged1 and theory of4             
,augustine1 ,st4    ,,aurora island1 an 
upraised atoll4    ,aurora4    ,,austral
 islands1 recently elevated4    ,austral
 islands4    ,australia1 ,n4,w4 coast4  
,,australian barrier-reef4              
,australian barrier4    ,babuyan group4 
,bahama banks4    ,balahac4    ,bally4  
,baring4    ,,barrier-,,reef of         
,australia4 ,of ,new ,caledonia4        
,,barrier-,,reefs1 breaches through4    
,not based on worn down margin of rock4 
,on banks of sediment4 ,on submarine    
craters4 ,steepness of their flanks4    
,their probable vertical thickness4     
,theory of their formation4    ,bampton 
shoal4    ,banks islands4    ,banks in  
the ,west ,indies4    ,bashee islands4  
,bass island4    ,batoa4    ,beaupre    
reef4    ,,beechey1 ,captain1           
obligations of the author to4 ,on       
submerged reefs4  ,account of ,matilda  
island4    ,,belcher1 ,captain1 on      
boring through coral-reef4    ,belize   
reef1 off4    ,bellinghausen4           

,bermuda islands4    ,beveridge reef4   
,bligh4    ,,bolabola1 view of4         
,bombay shoal4    ,bonin ,bay4    ,bonin
 group4    ,,borings through            
coral-reefs4    ,,borneo1 ,w4 coast1    
recently elevated4    ,borneo1 ,e4      
coast4 ,s4,w4 and ,w4 coast ,n4 coast4  
,western bank4    ,boscawen4    ,boston4
    ,bouka4    ,bourbon4    ,bourou4    
,bouton4    ,,brazil1 fringing-reefs on 
coast of4    ,,breaches through         
barrier-reefs4    ,brook4    ,bunker4   
,bunoa4    ,,byron4    ,cagayanes4      
,candelaria4    ,cargados ,carajos4     
,caroline archipelago4    ,caroline     
island4    ,carteret shoal4             
,,caryophyllia1 depth at which it lives4
    ,cavilli4    ,cayman island4        
,celebes4    ,ceram4    ,,ceylon1       
recently elevated4    ,ceylon4          
,,chagos ,great ,bank1 description and  
theory of4    ,,chagos group4    ,chagos
 group4    ,,chama-,,shells embedded in 
coral-rock4    ,,chamisso1 on corals    
preferring the surf4    ,,changes in the

 state of ,keeling atoll4 ,of atolls4   
,,channels leading into the lagoons of  
atolls4 ,into the ,maldiva atolls4      
,through barrier-reefs4    ,chase4      
,china sea4    ,,christmas atoll4       
,christmas atoll4    ,christmas island  
7,indian ,ocean74    ,clarence4         
,clipperton rock4    ,,cocos1 or        
,keeling atoll4    ,cocos 7or ,keeling74
    ,cocos island 7,pacific74           
,,cochin ,china1 encroachments of the   
sea on the coast4    ,cochin ,china4    
,coetivi4    ,comoro group4             
,,composition of coral-formations4      
,,conglomerate coral-rock on ,keeling   
atoll4 ,on other atolls4 ,coral-rock4   
,,cook islands1 recently elevated4      
,cook islands4    ,,coral-,,blocks bored
 by vermiform animals4                  
,,coral-,,reefs1 their distribution and 
absence from certain areas4  ,destroyed 
by loose sediment4    ,,coral-,,rock at 
,keeling atoll4 ,mauritius4 ,organic    
remains of4    ,,corals dead but upright
 in ,keeling lagoon4 ,depths at which   

they live4  ,off ,keeling atoll4 ,killed
 by a short exposure4 ,living in the    
lagoon of  ,keeling atoll4 ,quick growth
 of1 in ,keeling lagoon4 ,merely coating
 the  bottom of the sea4 ,standing      
exposed in the ,low archipelago4        
,,corallian sea4    ,corallian sea4     
,cornwallis4    ,cosmoledo4             
,,couthouy1 ,mr41 alleged proofs of     
recent elevation of the ,low            
archipelago4 ,on coral-rock at ,mangaia 
and ,aurora islands4 ,on external       
ledges round coral-islands4 ,remarks    
confirmatory of the author's  theory4   
,,crescent-,,formed reefs4    ,cuba4    
,,cuming1 ,mr41 on the recent elevation 
of the ,philippines4    ,dangerous1 or  
,low archipelago4    ,danger islands4   
,,depths at which reef-building corals  
live4 ,at ,mauritius1 the ,red ,sea1    
and in the ,maldiva archipelago4 ,at    
which other corals and corallines  can  
live4    ,dhalac group4    ,,diego      
,,garcia1 slow growth of reef4          
,,dimensions of the larger groups of    

atolls4    ,,disseverment of the        
,maldiva atolls1 and theory of4         
,,distribution of coral-reefs4          
,domingo1 ,st4    ,,dory1 ,port1        
recently elevated4    ,dory1 ,port4     
,duff islands4    ,durour4    ,eap4     
,,earthquakes at ,keeling atoll4 ,in    
groups of atolls4 ,in ,navigator        
archipelago4    ,,east ,,indian         
,,archipelago1 recently elevated4       
,easter4    ,echequier4    ,,ehrenberg1 
on the banks of the ,red ,sea4 ,on      
depths at which corals live  in the ,red
 ,sea4 ,on corals preferring the surf4  
,on the antiquity of  certain corals4   
,eimeo4    ,,elevated reef of           
,mauritius4    ,,elevations1 recent     
proofs of4 ,immense areas of4    ,elivi4
    ,,elizabeth island4 ,recently       
elevated4    ,elizabeth island4         
,ellice group4    ,,encircled ,,islands1
 their height4 ,geological composition4 
,,eoua1 description of4    ,eoua4       
,,erupted ,,matter probably not         
associated with thick masses of         

coral-rock4    ,,fais1 recently         
elevated4    ,fais4    ,fanning4        
,farallon de ,medinilla4    ,farson     
group4    ,fataka4    ,,fiji            
archipelago4    ,,fish1 feeding on      
corals4 ,killed in ,keeling lagoon by   
heavy rain4    ,,fissures across        
coral-islands4    ,,fitzroy1 ,captain1  
on a submerged shed at ,keeling atoll4  
,on an  inundation in the ,low          
archipelago4    ,flint4    ,flores4     
,florida4    ,folger4    ,formosa4      
,,forster1 theory of coral-formations4  
,frederick reef4    ,freewill4          
,,friendly group recently elevated4     
,friendly archipelago4                  
,,fringing-,,reefs1 absent where coast  
precipitous4 ,breached in front of      
streams4 ,described by ,,mm4 ,quoy and  
,gaimard4 ,not closely attached to      
shelving coasts4 ,of east coast of      
,africa4 ,of ,cuba4 ,of ,mauritius4 ,on 
worn down banks of rock4 ,on banks of   
sediment4 ,their appearance when        
elevated4 ,their growth influenced by   

currents4 ,by shallowness of sea4       
,galapagos archipelago4    ,galega4     
,,gambier islands1 section of4          
,gambier islands4    ,gardner4          
,gaspar rico4    ,,geological           
,,composition of coral-formations4      
,gilbert archipelago4    ,gilolo4       
,glorioso4    ,,gloucester ,island4     
,glover reef4    ,gomez4    ,gouap4     
,goulou4    ,grampus4    ,gran ,cocal4  
,,great ,,chagos ,,bank1 description and
 theory of4    ,,grey1 ,captain1 on     
sandbars4    ,,grouping of the different
 classes of reefs4    ,guedes4          
,,hall1 ,captain ,b41 on ,loo ,choo4    
,,harvey islands1 recently elevated4    
,,height of encircled islands4          
,hermites4    ,hervey or ,cook islands4 
,hogoleu4    ,,holothuriae 7,holuthuri7 
feeding on coral4    ,,houden island1   
height of4    ,honduras1 reef off4      
,horn4    ,houtman ,abrolhos4           
,,huaheine2 alleged proofs of its recent
 elevation4    ,huaheine4    ,humphrey4 
,hunter4    ,,hurricanes1 effects of1 on

 coral-islands4    ,immaum4             
,independence4    ,,india1 west coast1  
recently elevated4    ,india4           
,,irregular ,,reefs in shallow seas4    
,,islets of coral-rock1 their formation4
 ,their destruction in the ,maldiva     
atolls4    ,jamaica4    ,jarvis4        
,,java1 recently elevated4    ,java4    
,johnston island4    ,juan de ,nova4    
,juan de ,nova 7,madagascar74           
,kalatoa4    ,,kamtschatka1 proofs of   
its recent elevation4    ,karkalang4    
,,keeling atoll1 section of reef4       
,keeling1 south atoll4 ,north atoll4    
,keffing4    ,kemin4    ,kennedy4       
,keppel4    ,kumi4    ,laccadive group4 
,,ladrones1 or ,marianas1 recently      
elevated4    ,ladrones archipelago4     
,,lagoon of ,keeling atoll4    ,,lagoons
 bordered by inclined ledges and walls1 
and theory of their  formation4 ,of     
small atolls filled up with sediment4   
,,lagoon-,,channels within              
barrier-reefs4    ,,lagoon-,,reefs1 all 
submerged in some atolls1 and rising to 

the surface  in others4    ,lancaster   
reef4    ,latte4    ,lauglan islands4   
,,ledges round certain lagoons4         
,lette4    ,lighthouse reef4    ,,lloyd1
 ,mr41 on corals refixing themselves4   
,,loo ,,choo1 recently elevated4    ,loo
 ,choo4    ,louisiade4    ,,low         
,,archipelago1 alleged proofs of its    
recent elevation4    ,low archipelago4  
,,lowness of coral-islands4    ,loyalty 
group4    ,lucepara4    ,,lutke1        
,admiral1 on fissures across            
coral-islands4    ,,luzon1 recently     
elevated4    ,luzon4    ,,lyell1 ,mr41  
on channels into the lagoons of atolls4 
,on the lowness of  their leeward sides4
 ,on the antiquity of certain corals4   
,on the  apparent continuity of distinct
 coral-islands4 ,on the recently        
elevated  beds of the ,red ,sea4 ,on the
 outline of the areas of subsidence4    
,macassar strait4    ,macclesfield bank4
    ,,madagascar1 quick growth of corals
 at4 ,madreporitic rock of4             
,madagascar4    ,madjiko-sima4          

,madura 7,java74    ,madura 7,india74   
,,mahlos ,,mahdoo1 theory of formation4 
,,malacca1 recently elevated4           
,malacca4    ,,malcolmson1 ,dr41 on     
recent elevation of ,w4 coast of ,india4
 ,on recent  elevation of ,camaran      
island4    ,malden4    ,,maldiva atolls1
 and theory of their formation4         
,steepness of their  flanks4 ,growth of 
coral at4    ,maldiva archipelago4      
,,mangaia island4 ,recently elevated4   
,mangaia4    ,mangs4    ,,marianas1     
recently elevated4    ,mariana          
archipelago4    ,mariere4    ,marquesas 
archipelago4    ,marshall archipelago4  
,marshall island4    ,martinique4       
,martires4    ,,mary',s ,,st41 in       
,madagascar1 harbour made in reefs4     
,mary island4    ,matia1 or ,aurora4    
,,matilda atoll4    ,,mauritius1        
fringing-reefs of4 ,depths at which     
corals live there4  ,recently elevated4 
,mauritius4    ,,maurua1 section of4    
,maurua4    ,,menchikoff atoll4         
,mendana archipelago4    ,mendana isles4

    ,mexico1 gulf of4    ,,millepora    
,,complanata at ,keeling atoll4         
,mindoro4    ,mohilla4 7,mohila47       
,,molucca islands1 recently elevated4   
,mopeha4    ,,moresby1 ,captain1 on     
boring through coral-reefs4    ,morty4  
,mosquito coast4    ,,musquillo atoll4  
,mysol4    ,,namourrek group4           
,natunas4    ,,navigator archipelago1   
elevation of4    ,navigator archipelago4
    ,nederlandisch4    ,,nelson1        
,lieutenant1 on the consolidation of    
coral-rocks under water4  ,theory of    
coral-formations4 ,on the ,bermuda      
islands4    ,new ,britain4    ,,new     
,,caledonia1 steepness of its reefs4    
,barrier-reef of4    ,new ,caledonia4   
,new ,guinea 7,e4 end74    ,new ,guinea 
7,w4 end74    ,new ,hanover4    ,,new   
,,hebrides1 recently elevated4    ,new  
,hebrides4    ,,new ,,ireland1 recently 
elevated4    ,new ,ireland4    ,new     
,nantucket4    ,nicobar islands4        
,niouha4    ,,nulliporae at ,keeling    
atoll4 ,on the reefs of atolls4 ,on     

barrier-reefs4  ,their wide distribution
 and abundance4    ,,objections to the  
theory of subsidence4    ,ocean islands4
    ,ono4    ,onouafu4 7,onouafou47     
,ormuz4    ,oscar group4                
,,oscillations of level4    ,ouallan1 or
 ,ualan4 7,oualan47    ,,ouluthy atoll4 
,outong ,java4    ,palawan1 ,s4,w4      
coast4 ,n4,w4 coast4 ,western bank4     
,palmerston4    ,palmyra4    ,paracells4
    ,paraquas4    ,patchow4    ,pelew   
islands4    ,,pemba island1 singular    
form of4    ,pemba4    ,penrhyn4        
,peregrino4    ,,pernambuco1 bar of     
sandstone at4    ,,persian gulf1        
recently elevated4    ,persian gulf4    
,,pescado4    ,pescadores4    ,peyster  
group4    ,philip4    ,,philippine      
archipelago1 recently elevated4         
,philippine archipelago4    ,phnix4     
,piguiram4    ,pitcairn4    ,,pitt',s   
bank4    ,pitt island4    ,platte4      
,pleasant4    ,,porites1 chief coral on 
margin of ,keeling atoll4               
,postillions4    ,,pouynipete4 ,its     

probable subsidence4    ,pouynipte4     
,pratas shoal4    ,proby4               
,providence4    ,puerto ,rico4    ,pulo 
,anna4    ,,pumice floated to           
coral-islands4    ,pylstaart4           
,,pyrard ,,de ,,laval1 astonishment at  
the atolls in the ,indian ,ocean4       
,,quoy ,,and ,,gaimard1 depths at which 
corals live4 ,description of reefs      
applicable only to fringing-reefs4      
,,range of atolls4    ,rapa4            
,rearson4    ,,red ,,sea1 banks of rock 
coated by reefs4 ,proofs of its recent  
elevation4  ,supposed subsidence of4    
,red ,sea4    ,,reefs1 irregular in     
shallow seas4 ,rising to the surface in 
some lagoons  and all submerged in      
others4 ,their distribution4 ,their     
absence from  some coasts4              
,revilla-gigedo4    ,,ring-,,formed     
,,reefs of the ,maldiva atolls1 and     
theory of4    ,rodriguez4    ,rosario4  
,rose island4    ,rotches4    ,rotoumah4
    ,roug4    ,rowley shoals4           
,,ruppell1 ,dr41 on the recent deposits 

of ,red ,sea4    ,sable1 ile de4        
,sahia de ,malha4    ,st4 ,pierre4      
,sala4    ,salomon archipelago4         
7,solomon47    ,,samoa1 or ,navigator   
archipelago1 elevation of4    ,samoa    
archipelago4    ,,sand-,,bars parallel  
to coasts4    ,sandal-wood4             
,,sandwich archipelago1 recently        
elevated4    ,sandwich archipelago4     
,sanserot4    ,santa-,cruz group4       
,,savage island1 recently elevated4     
,savage4    ,savu4    ,saya1 or ,sahia  
de ,malha4    ,scarborough shoal4       
,,scarus feeding on corals4             
,schouten4    ,scilly4    ,,scoriae     
floated to coral-islands4    ,scott's   
reef4    ,,sections of islands encircled
 by barrier-reefs4 ,of ,bolabola4       
,,sediment in ,keeling lagoon4 ,in other
 atolls4 ,injurious to corals4          
,transported from coral-islands far     
seaward4    ,seniavine4    ,serangani4  
,seychelles4    ,,ship-,,bottom quickly 
coated with coral4    ,,smyth island4   
,,society archipelago1 stationary       

condition of4 ,alleged proofs of recent 
elevation4    ,society archipelago4     
,socotra4    ,solor4    ,,sooloo        
islands1 recently elevated4    ,sooloo  
islands4    ,souvaroff4    ,spanish4    
,,sponge1 depths at which found4        
,starbuck4 7,slarbuck47    ,,stones     
transported in roots of trees4          
,,storms1 effects of1 on coral-islands4 
,,stutchbury1 ,mr41 on the growth of an 
,agaricia4 ,on upraised corals in       
,society archipelago4    ,,subsidence of
 ,keeling atoll4 ,extreme slowness of4  
,areas of1 apparently  elongated4 ,areas
 of immense4 ,great amount of4    ,suez1
 gulf of4    ,sulphur islands4          
,,sumatra1 recently elevated4           
,sumatra4    ,sumbawa4    ,,surf        
favourable to the growth of massive     
corals4    ,swallow shoal4    ,sydney   
island4    ,,tahiti1 alleged proofs of  
its recent elevation4    ,tahiti4       
,,temperature of the sea at the         
,galapagos archipelago4    ,tenasserim4 
,tenimber island4    ,teturoa4          

,,theories on coral-formations4         
,,theory ,,of subsidence1 and objections
 to4    ,,thickness1 vertical1 of       
barrier-reefs4    ,thomas1 ,st4         
,tikopia4    ,,timor1 recently elevated4
    ,timor4    ,timor-laut4             
,tokan-,bessees4    ,tongatabou4        
,tonquin4    ,toubai4    ,toufoa4       
7,toofoa47    ,toupoua4    ,,traditions 
,,of ,,change in coral-islands4         
,,tridacnae embedded in coral-rock4     
,left exposed in the ,low archipelago4  
,,tubularia1 quick growth of4           
,tumbelan4    ,turneffe reef4           
,turtle4    ,ualan4    ,,vanikoro1      
section of4 ,its state and changes in   
its reefs4    ,vanikoro4    ,vine reef4 
,virgin ,gorda4    ,viti archipelago4   
,,volcanic islands1 with living corals  
on their shores4 ,matter1 probably  not 
associated with thick masses of         
coral-rock4    ,,volcanoes1 authorities 
for their position on the map4 ,their   
presence  determined by the movements in
 progress4 ,absent or extinct in the    

areas  of subsidence4    ,waigiou4      
,wallis island4    ,washington4         
,well's reef4    ,,wellstead1           
,lieutenant1 account of a ship coated   
with corals4    ,,west ,,indies1 banks  
of sediment fringed by reefs4 ,recently 
elevated4    ,west ,indies4             
,,whitsunday island1 view of4 ,changes  
in its state4    ,,williams1 ,rev4 ,j41 
on traditions of the natives regarding  
coral-islands4 ,on antiquity of certain 
corals4    ,wolchonsky4    ,wostock4    
,xulla islands4    ,york island4        
,yucutan1 coast of4    ,,zones of       
different kinds of corals outside the   
same reefs4