,transcriber ,note  ,text emphasis      
denoted as ,italic and ,small ,caps4    
,,the                                   
,,journal ,,of ,,geology                
,,january-,,february1 #ahic4            
99       99       99       99       99  
,,on ,,the ,,pre-,,cambrian ,,rocks ,,of
 ,,the ,,british ,,isles4   ,during the 
last twenty years much has been written 
about the pre-,cambrian rocks of the    
,british ,isles4 ,unfortunately when    
attention began to be sedulously given  
to the study of these ancient           
formations1 the problems of metamorphism
 were still a hundred fold more obscure 
than they have since become2 the aid of 
the microscope had not been seriously   
and systematically adopted for the      
investigation of the crystalline        
schists1 and geologists generally were  
still under the belief that the broad   
structure of these schists could be     
treated like those of the sedimentary   
rocks1 and be determined by rapid       
traverses of the ground4 ,we have now   

painfully discovered that these older   
methods of observation were extremely   
crude1 and that the work performed in   
accordance with them is now of little   
interest or value save as a historical  
warning to future generations of        
geologists4 ,geological literature has  
meanwhile been burdened with numerous   
contributions which remain as a         
permanent incubus on our library        
shelves4  ,it may serve a useful purpose
 at the present time in possibly aiding 
those who are engaged in the study of   
the oldest rocks of ,north ,america1 if 
,i place before them1 as briefly as     
possible1 the main facts which in my    
opinion have now been satisfactorily    
proved regarding the corresponding rocks
 of ,britain1 and if ,i indicate at the 
same time some of the more probable     
inferences in those cases where the     
facts1 at present known1 do not warrant 
a definite conclusion4  ,it is obvious  
that in any effort to establish that a  
group of rocks is older than the very   

base of the sedimentary fossiliferous   
formations1 we must somewhere find that 
group emerging from under the bottom of 
these formations4 ,until lithological   
characters are ascertained to be so     
distinctive and constant as to be       
comparable to fossil evidence for       
purposes of stratigraphical             
identification1 we should not assume    
that detached areas of older rocks      
rising amid ,palozoic1 ,secondary or    
,tertiary formations are pre-,cambrian4 
,we should1 if possible1 begin at the   
bottom of the ,palozoic systems and work
 backward1 tracing each successive      
system or group as these rise from under
 each other1 until we arrive at what    
appears to be the oldest traceable      
within the region of observation4 ,it is
 clear that in the present state of     
knowledge we have no satisfactory means 
of identifying such successive systems  
in widely separated countries4 ,all that
 can be attempted in the meantime is to 
ascertain the special types in each     

region1 and to point out their general  
resemblances or contrasts to those of   
other regions4 ,it is better to avoid   
confusion by refraining from applying   
the stratigraphical names adopted for   
the oldest rocks of one region to those 
of another geographically remote1 though
 we may hope that eventually it may be  
possible to work out the equivalence of 
these local names4  ,in the ,british    
,isles1 by much the most important      
region for the study of the oldest rocks
 is to be found in the north-west       
,highlands of ,scotland4 ,the very      
basement strata of the ,cambrian system 
are there traceable for a distance of   
more than #ajj miles1 reposing with a   
strong unconformability upon all rocks  
of older date4 ,they consist of         
dolomitic shales with ,olenellus1       
resting upon a thick group of           
quartzites1 full of annelid tubes4 ,one 
of the most remarkable features of these
 ancient strata is the persistence of   
their component bands or zones which1   

though sometimes only a few feet thick1 
can be traced throughout the whole tract
 of country just referred to4 ,for the  
study of the pre-,cambrian rocks this is
 an important point1 for we can be quite
 certain that even where fossil evidence
 locally fails1 the same basement       
members of the ,cambrian system are     
persistent and lie directly upon the    
pre-,cambrian series4  ,lewisian        
,gneiss4 ,ever since the researches of  
,murchison and ,nicol in the north-west 
of ,scotland1 it has been known that two
 distinct systems of rock underlie the  
quartzites to which ,i have just        
alluded4 ,murchison regarded the upper  
of these as of ,cambrian age1 while he  
assigned the unconformable quartzites   
and limestones above it to the ,lower   
,silurian period4 ,but the recent       
discovery of the ,olenellus zone        
intercalated conformably between the    
quartzites and the overlying limestones 
may be regarded as proving that all the 
rocks which underlie the quartzites and 

are separated from them by a strong     
unconformability must be pre-,cambrian4 
,it is thus established beyond any      
reasonable doubt that two great         
pre-,cambrian systems of rock exist in  
the north-west of ,scotland4  ,these two
 systems differ so entirely from each   
other that their respective areas can be
 defined with minute accuracy4 ,the     
uppermost consists chiefly of dull      
reddish sandstones with conglomerates1  
and especially towards their base in    
,rosshire1 some bands of dark grey      
shale1 the whole having a thickness of  
at least #h1jjj or #aj1jjj feet1 though 
as both the base and the top of the     
series are marked by strong             
unconformabilities1 the whole original  
thickness of deposits is nowhere seen4  
,as these rocks are well developed      
around ,loch ,torridon1 they were named 
by ,nicol the ,torridon ,sandstone--a   
designation which has more recently been
 shortened into ,torridonian4 ,the lower
 system is mainly composed of various   

foliated rocks which may be embraced    
under the general term gneiss4 ,these   
masses present the usual characters of  
the so-called fundamental complex1      
,urgebirge1 or ,archan ,series of other 
countries4 ,the contrast between the    
thoroughly crystalline1 gnarled1        
ancient-looking gneisses below1 and the 
overlying1 nearly horizontal            
,torridonian conglomerates1 sandstones1 
and shales1 which are largely made out  
of their debris1 is so striking that    
every observer feels persuaded that in  
any logical system of classification    
they can not be both placed in the same 
division of the geological record4 ,they
 are certainly both pre-,cambrian1 but  
they must belong to widely separated    
eras1 and must have been produced by    
entirely different processes4 ,if it is 
proposed to regard the gneisses as      
,archan1 we must refuse to include the  
,torridonian strata in the same section 
of pre-,cambrian time4 ,but so much     
uncertainty exists as to the application

 of this term ,archan1 examples are so  
multiplying wherein what was supposed to
 be the oldest and truly ,archan rock is
 found to be intrusive in rocks that    
were taken to be of much younger date1  
and there are such slender grounds for  
correlating the so-called ,archan rocks 
of one country with those of another1   
that ,i prefer for the present1 at      
least1 not to use the term at all4 ,let 
me very briefly state some of the main  
characteristics of the two sharply      
contrasted rock-systems of the          
north-west of ,scotland4  ,the oldest   
gneiss of that region was originally    
called ,lewisian by ,murchison1 from its
 large development in the ,island of    
,lewis1 and ,i think it would be1 for   
the present at least1 an advantage to   
retain this geographical appellation4   
,at first this fundamental gneiss was   
thought to be a comparatively simple    
formation1 and the general impression   
probably was that it should be regarded 
as a metamorphic mass1 produced mainly  

from the alterations of very ancient    
stratified rocks4 ,its foliation-planes 
were believed to be those of original   
deposit which by terrestrial disturbance
 had been thrown into numerous          
plications and corrugated puckerings4   
,but a detailed study of this primeval  
rock has revealed in it a far more      
complicated structure4 ,the supposed    
bedding-planes have been ascertained to 
have nothing to do with sedimentary     
stratification1 and the gneiss has been 
resolved into a complex series of       
eruptive rocks1 varying from a highly   
basic to an acid type1 and manifestly   
belonging to different times of         
extrusion4 ,with the exception of one   
district1 to which ,i shall immediately 
refer1 no part of the whole region yet  
examined has revealed to the rigid      
scrutiny of my colleagues of the        
,geological ,survey1 any trace of rocks 
which can be regarded as probably of    
other than igneous origin4 ,it is true  
that our researches have been hitherto  

confined to the mainland of ,scotland1  
the large area of the ,outer ,hebrides1 
which consists of similar gneisses1     
remaining to be explored4 ,it is        
therefore possible that indisputable    
evidence of an ancient sedimentary      
series through which the gneiss was     
originally protruded1 may yet be        
discovered in the unexplored islands4   
,but taking the gneiss as at present    
known in ,sutherland and ,rosshire1 we  
find it to be generally coarse in       
texture1 rudely foliated1 and passing   
sometimes into massive types in which   
foliation is either faintly developed or
 entirely absent4 ,much of this gneiss  
is considerably more basic than the more
 typical rocks to which the term gneiss 
was formerly restricted4 ,it consists of
 plagioclase felspar with pyroxene1     
hornblende1 and magnetite1 sometimes    
with blue opalescent quartz1 and        
sometimes with black mica4 ,these       
predominant minerals are segregated in  
different proportions in the different  

bands1 some bands consisting mainly of  
pyroxene or hornblende1 with little or  
no plagioclase1 others chiefly of       
plagioclase1 with small quantities of   
the ferro-magnesian minerals and quartz1
 others of plagioclase and quartz1      
others of magnetite4 ,this separation of
 mineral constituents can hardly be     
attributed to mere mechanical           
deformation4 ,it rather resembles the   
segregation layers which may be studied 
in intrusive sills and other deep-seated
 masses of eruptive material1 and which 
are obviously due to a process of       
separation that went on while the       
igneous magma was still in a liquid or  
viscous condition4 ,at the same time it 
is manifest that extensive dynamical    
changes have affected the rocks since   
the appearance of this original banded  
structure4  ,there is further evidence  
that beside the original eruptive       
masses1 which for want of any means of  
discriminating their relative dates of  
protrusion must in the meantime be      

regarded as belonging to one eruptive   
period1 other portions of igneous       
material have been subsequently and at  
successive epochs1 after the first      
mechanical deformations1 injected into  
the body of the original gneiss4 ,these 
consist of dykes of basalt and dolerite1
 followed by still more basic           
peridotites and picrites1 and lastly by 
emanations from a distinctly acid magma 
in the form of granites4 ,the oldest or 
doleritic dykes form a wonderful feature
 in the gneiss1 from their abundance1   
persistence and uniformity of trend in a
 west-northwest direction4 ,they have no
 parallel in ,british ,geology until we 
reach the crowded dykes of older        
,tertiary time4  ,throughout this       
remarkable complex of eruptive material1
 though its different portions present  
many features that may be compared with 
those of intrusive bosses and sheets    
belonging to later geological periods1  
there is no trace of any superficial    
volcanic manifestation4 ,no tuffs or    

agglomerates or slaggy lavas have been  
detected1 such as might serve to        
indicate the ejection of volcanic       
materials to the surface4 ,all the      
phenomena of the ,lewisian gneiss point 
to the consolidation of successively    
protruded portions of eruptive material 
at some depth within the crust4         
,nevertheless it may yet be possible to 
show that these deep seated masses have 
been injected into rocks of older date  
and of sedimentary origin1 and that they
 have communicated with the surface in  
true volcanic eruptions4 ,i have already
 alluded to one limited area where      
various rocks exist1 distinctly         
different from the prevalent types in   
the ,lewisian gneiss4 ,in the area which
 is traversed by the long valley of     
,loch ,maree in western ,rosshire1 there
 occur clay-slates1 fine mica schists1  
graphitic schists1 and saccharoid       
limestones4 ,these rocks remind us of   
some of the prevalent members of a      
series of metamorphosed sediments4 ,the 

minerals enclosed in the marbles are    
just such as might be expected in the   
metamorphic aureole of a granite boss1  
piercing limestone4 ,but the relations  
of this group of rocks to the ordinary  
gneiss of the region are not quite so   
clear as could be desired1 though they  
seem to point to these rocks being      
surrounded by and enclosed within the   
gneiss4  ,the detailed field-work of the
 officers of the ,geological ,survey has
 made known the remarkable amount of    
mechanical deformation which the various
 rock-masses composing the ,lewisian    
gneiss have undergone4 ,these rocks have
 been compressed1 crushed1 and drawn    
out1 until what were originally massive 
crystalline protrusions have been       
converted into perfect schists4 ,the    
dykes of dolerite have been transformed 
into hornblende-schists and the granitic
 pegmatites have been reduced to a kind 
of powder which has been rolled out so  
as to simulate the flow-structure of a  
lava4 ,there is evidence that most1 if  

not all1 of this dynamical change was   
effected long before the deposition of  
the ,torridonian series1 for the latter 
rests in nearly horizontal sheets1 with 
a strong unconformability upon the      
crushed and sheared gneiss4  ,torridon  
,sandstone4 ,this group of rocks covers 
only a limited area in the north-west of
 ,scotland1 but it must once have spread
 over a far more extensive region4 ,it  
reaches a thickness1 as ,i have said1 of
 #h1jjj or #aj1jjj feet1 and consists   
almost wholly of dull1 purplish-red     
sandstones1 often pebbly1 and bands of  
conglomerate4 ,dark grey shales1 already
 alluded to as occurring towards the    
base of the series1 are repeated also in
 the highest visible portion1 and have  
yielded tracks of what seem to have been
 annelids and casts of nail-like bodies 
which may have been organic4 ,i have    
said that the ,torridonian deposits     
which were classed by ,murchison as     
,cambrian1 have been proved by the      
discovery of the ,olenellus zone in an  

unconformable position above them1 to be
 of pre-,cambrian age4 ,except along the
 line of disturbance to which ,i shall  
immediately refer1 these strata are     
quite unaltered4 ,indeed1 in general    
aspect they look as young as the old red
 sandstones with which ,hugh ,miller    
identified them4 ,it is at first hard to
 believe that such flat undisturbed     
sandstones are of higher antiquity than 
the very oldest ,palozoic strata which  
are so generally plicated and cleaved4  
,the interval of time between the       
deposition of the ,torridon ,sandstone  
and of the overlying ,cambrian          
formations must have been of enormous   
duration1 for the unconformability is so
 violent that the lowest ,cambrian      
strata1 not only transgressively        
overspread all the ,torridonian         
horizons1 but even lie here and there   
directly on the old gneiss1 the whole of
 the intervening thick mass of sandstone
 having been there removed by previous  
denudation4 ,at ,durness1 in the north  

of ,sutherland1 about #bjjj feet of     
,cambrian 7possibly in part ,lower      
,silurian7 strata can be traced1 the    
lower portion consisting of quartzites1 
the central and upper parts of various  
limestones1 sometimes abundantly        
fossiliferous4 ,nowhere else in the     
north of ,scotland can so thick a mass  
of early ,palozoic rocks be seen4       
,elsewhere the limestones have been in  
large measure replaced by a complex     
group of schistose rocks which rest upon
 the ,cambrian strata1 and like them    
dip1 generally at gentle angles1 towards
 the east4 ,it was the opinion of       
,murchison1 and was commonly admitted by
 geologists1 that these overlying       
schists represented a thick group of    
sediments1 which1 originally deposited  
continuously after the limestones1 had  
been subsequently altered into their    
present condition by regional           
metamorphism4 ,they were variously named
 the ,eastern schists1 the younger      
gneiss1 the gneissose and quartzose     

flagstones4 ,nicol1 who at first shared 
the general opinion regarding them1     
afterwards maintained that they did not 
belong to a later formation than the    
limestones1 but were really only the old
 gneiss1 brought up again from beneath  
by enormous dislocations and            
over-thrusts4 ,we now know from the     
labors of ,professor ,lapworth and the  
officers of the ,geological ,survey1    
that ,murchison and ,nicol had each     
seized on an essential part of the      
problem1 but that both of them had      
missed the true solution4 ,murchison was
 in error in regarding his younger      
gneiss as a continuous sequence of      
altered sedimentary rocks conformably   
resting on the ,cambrian 7or to use his 
terminology1 ,lower-,silurian7          
formations4 ,but he sagaciously observed
 the coincidence of dip and strike      
between the schists and sedimentary     
rocks below them and inferred that this 
coincidence1 traceable for many leagues1
 proved that the metamorphism which had 

given these schists their structure must
 have taken place after the deposition  
of the ,durness limestones4 ,nicol1 on  
the other hand1 with great insight      
recognized that there was no continuous 
sequence above those limestones1 but    
that masses of the old gneiss had been  
thrust over them by gigantic faults4    
,but he failed to see that no mere      
faults would account for the coincidence
 between the structural lines just      
referred to in the ,cambrian strata1 and
 in the overlying schists1 and that the 
general tectonic structures and         
lithological characters of the eastern  
schists differed in many respects from  
those of the ,lewisian gneiss4  ,the    
problems in tectonic geology presented  
by the complicated structures of the    
northwest of ,scotland have been ably   
worked out by the officers of the       
,geological ,survey1 to whose report in 
the ,quarterly ,journal of the          
,geological ,society for #ahhh1 ,i would
 refer for full details4 ,it has been   

shown that1 besides stupendous          
dislocations and horizontal             
displacements1 the rocks have been cut  
into innumerable slices which have been 
driven over each other from the         
eastward1 while at the same time there  
has been such a general shearing of the 
whole region that for many hundreds of  
square miles the original               
rock-structures have been entirely      
effaced1 and have been replaced by new  
divisional planes1 which1 when they     
approach the underlying ,cambrian       
strata1 are roughly parallel with the   
bedding planes of these strata4  ,in    
this region1 therefore1 we have striking
 proofs of a stupendous post-,cambrian  
regional metamorphism4 ,but there is    
still much uncertainty regarding the    
geological age of the rocks which have  
been affected by it4 ,there can be no   
doubt that large masses of the old      
gneiss1 torn up from below1 have been   
thrust bodily westward for many miles1  
and are now seen with their dykes and   

pegmatites resting on the ,durness      
limestones and quartzites4 ,it is       
equally certain that in other districts 
huge slices of the ,torridon sandstones 
have been similarly treated4 ,but where 
all trace of original structure has     
disappeared1 we have1 as yet1 no means  
of definitely determining from what     
formation the present eastern schists   
have been produced4 ,the ordinary       
gneissose and quartzose flagstones do   
not appear to me to be such rocks as    
could ever be manufactured by any       
chemical or mechanical process out of   
the average type of ,lewisian gneiss4 ,i
 have long held the belief that they    
were originally sediments1 but whether  
they represent altered ,torridon        
,sandstone1 or some clastic formations  
which may have followed the ,durness    
limestones1 but which have been         
everywhere and entirely metamorphosed1  
remains for future discovery4 ,for my   
present purpose1 it is sufficient to    
observe that1 in the meantime1 as we can

 not be sure of the origin of most of   
the rocks1 which1 between the ,west     
,coast and the line of the ,great ,glen1
 have been subjected to a gigantic      
post-,cambrian regional metamorphism1 it
 seems safest to exclude them from an   
enumeration of the pre-,cambrian rocks  
of ,britain4  ,dalradian4 ,east of the  
line of ,great ,glen1 which cuts the    
,scottish ,highlands in two1 another    
group of crystalline schistose rocks is 
largely developed4 ,it consists mainly  
of what were undoubtedly originally     
sedimentary deposits1 though they are   
now found in the form of quartzites1    
phyllites1 graphitic schists1           
mica-schists1 marbles1 and various other
 foliated masses4 ,with them are        
associated numerous eruptive rocks1 both
 acid and basic1 sometimes still massive
 and easily recognizable as intrusive1  
sometimes more or less distinctly       
foliated and passing into different     
gneisses1 hornblende-schists1           
chloritic-schists1 etc4 ,though it is   

not always possible in such a series of 
metamorphic rocks to be certain of any  
real chronological order of succession1 
those of the ,highland tracts have now  
been mapped in detail over so wide an   
area1 that we are probably justified in 
believing that a definite sequence can  
be established among them4 ,these masses
 must be many thousand feet thick4      
,their succession and association of    
materials are so unlike those of any of 
the known older ,palozoic rocks of      
,britain1 that they can hardly be the   
metamorphosed equivalents of any strata 
which can be recognized in an unaltered 
condition in these islands4 ,some traces
 of annelid casts have been found in the
 quartzites1 but otherwise the whole    
series has remained entirely barren of  
organic remains4  ,what then is the age 
of this important series8 ,i must       
confess that in the meantime ,i can give
 no satisfactory answer to this         
question4 ,i have proposed1 for the sake
 of distinction and convenient          

reference1 to call these rocks          
,dalradian4 ,murchison supposed them to 
be a continuation of his ,durness       
quartzites1 limestones1 and younger     
gneiss4 ,his belief may still prove to  
be in some measure well founded4 ,but at
 present we have no means of deciding   
whether the quartzites and limestones of
 the ,central ,highlands are the more   
altered equivalents of the undoubtedly  
,cambrian strata of the north-west4 ,it 
is possible that in the vast mass of    
metamorphosed rocks constituting the    
wide stretch of country from the        
northern headlands of ,aberdeen to the  
south-western promontories of           
,argyllshire1 there may be portions of  
the old ,lewisian gneiss1 tracts of     
highly altered ,torridon sandstone1     
belts of true counterparts of the       
,cambrian quartzites and limestones of  
,durness1 and1 what should not be       
forgotten1 considerable portions of some
 later sedimentary series which may have
 followed these limestones1 but which1  

by the great dislocations already       
referred to1 have disappeared from the  
north-west of ,scotland4 ,we are        
gradually learning more of these rocks1 
as the detailed mapping of them by the  
,geological ,survey advances1 and when  
the ground on either side of the ,great 
,glen is surveyed1 it may be possible to
 speak with more certainty regarding    
their true geological relations4  ,a    
glance at a geological map of the       
,british ,isles will show that the      
metamorphic rocks of the south-western  
,highlands of ,scotland are prolonged   
into the north of ,ireland1 where they  
spread over a region many hundred square
 miles in extent4 ,they retain there the
 same general character and present the 
same difficult problems as to their true
 stratigraphical relations4 ,quite      
recently1 however1 a new light seems to 
have arisen upon these ,irish rocks4 ,my
 colleagues on the ,irish ,branch of the
 ,geological ,survey have detected      
several detached areas of coarse        

gneisses1 which in many respects        
resemble parts of the ,lewisian gneiss  
of north-west ,scotland4 ,in some cases 
these areas lie amidst or close to      
,dalradian rocks1 but with that         
obstinacy1 which so tries the patience  
of the field-geologist1 they have       
persistently refused to disclose their  
true original position with regard to   
these4 ,some fault1 thrust-plane1 tract 
of boulder-clay or stretch of bog is    
sure to intervene along the very        
junction-line where the desired sections
 might have been looked for4 ,there can 
be little doubt that a strong           
unconformability exists between them4 ,a
 close examination of the ridge of old  
gneiss in ,tyrone and ,fermanagh showed 
me that though the actual basement-beds 
of this ,dalradian series could not be  
seen resting on the coarse gneiss1 the  
lithological character1 and tectonic    
arrangement of this series are only     
explicable on the supposition of a      
complete discordance between it and the 

gneiss4 ,as these two groups of rock    
have never been found in close proximity
 in ,scotland1 and as the determination 
of the true age of the ,dalradian series
 is a question of such great            
stratigraphical importance in the       
general mapping of the ,united ,kingdom1
 ,i requested ,mr4 ,a4 ,mc,henry1 of the
 ,geological ,survey of ,ireland1 to    
continue the tracing of the mutual      
boundaries of the old gneiss of the ,ox 
,mountains and the ,dalradian series in 
,county ,mayo4 ,he informs me that he   
has found in that series a conglomerate 
full of blocks of the old gneiss1 and   
resting in one locality apparently      
unconformably upon it4 ,if this         
observation is confirmed it will finally
 set at rest the relative position of   
the coarse massive gneiss and some      
portion1 at least1 of the ,dalradian    
series4 ,of course there is no absolute 
proof that the coarse gneisses of       
,ireland are really the equivalents of  
the ,lewisian masses which they so      

closely resemble4 ,but there is a strong
 presumption in favor of their identity4
  ,in ,england and ,wales many detached 
areas of rock have been claimed as      
pre-,cambrian1 and successive formations
 have been classified among them4 ,i    
have already dealt in part with this    
question1 and without attempting here to
 review the voluminous literature of the
 subject1 ,i will content myself with   
stating briefly what seems to me to have
 been established on good evidence4     
,there can not1 ,i think1 be now any    
doubt that small tracts of gneiss1 quite
 comparable in lithological character to
 portions of the ,lewisian rocks of the 
north-west of ,scotland1 rise to the    
surface in a few places in ,england and 
,wales4 ,in the heart of ,anglesey1 for 
example1 a tract of such rocks presents 
some striking external or scenic        
resemblance to the characteristic types 
of ground where the oldest gneiss forms 
the surface in ,scotland and the west of
 ,ireland4 ,in the ,malvern ,hills      

another small knob of somewhat similar  
material is obviously far more ancient  
than the ,cambrian rocks of that        
locality4 ,there may possibly be still  
some further exposures of similar rocks 
in the south of ,england1 as for        
instance in southern ,cornwall4 ,in     
,anglesey a series of schists1          
quartzites and limestones has been      
included by ,mr4 ,j4 ,f4 ,blake with the
 coarse gneiss above referred to1 and a 
thick higher group of slates in what he 
terms the ,monian system4 ,these        
schists1 quartzites and limestones      
present a close resemblance to the      
,dalradian series of ,scotland and      
,ireland1 and the quartzites1 like those
 of the ,highlands1 contain             
worm-burrows4 ,the coarse gneiss1 as ,i 
have said1 may be compared in general   
character with parts of the ,lewisian   
rocks1 so that we seem to have here1 as 
in ,ireland1 two groups of schistose    
rocks1 and both of these must be much   
older than the unaltered ,cambrian      

strata which lie above them4  ,along the
 eastern borders of ,wales1 there is an 
interrupted ridge of igneous rocks which
 were originally supposed to have broken
 through the older ,palozoic formations1
 but which now1 owing mainly to the     
labors of ,dr4 ,callaway and ,professor 
,lapworth1 are shown to be older than   
the base of the ,cambrian system4 ,these
 rocks consist of spherulitic and       
perlitic felsites1 with volcanic        
breccias and tuffs4 ,they are           
undoubtedly older than the ,olenellus   
zone4 ,though the evidence is not quite 
satisfactory1 they may not impossibly   
lie at the base of a vast mass of       
sedimentary rocks forming the ridge of  
the ,longmynd4 ,in that case the whole  
of the ,longmynd succession with the    
volcanic group at its base must be      
pre-,cambrian and lie unconformably     
below the ,olenellus zone4 ,dr4         
,callaway has proposed the name         
,uriconian for this volcanic group1     
while the sedimentary series has been   

termed ,longmyndian4 ,on the supposition
 that the unconformability is           
established1 there would here be a vast 
mass of stratified and partly erupted   
material forming a pre-,cambrian        
formation4 ,whether in that case any    
portion of this ,english series is the  
equivalent of the ,torridonian rocks of 
,scotland remains to be determined4 ,the
 northwestern part of the ,longmynd     
ridge is made of red sandstones and     
conglomerates1 which certainly resemble 
the ,torridonian rocks of ,ross and     
,sutherland4  ,at the base of the       
,cambrian rocks in ,wales1 ,dr4 ,hicks  
has described a marked volcanic series  
under the name of ,pebidian1 which he   
claims as pre-,cambrian1 alleging that  
it is separated from the ,cambrian      
system by an unconformability1 and a    
band of conglomerates4 ,i have carefully
 studied the evidence on this ground1   
and have come to the conclusion that    
there is no unconformability at the line
 in question1 but that the ordinary     

,cambrian strata graduate downwards into
 the volcanic group and can not be      
disjoined from it4 ,i therefore regard  
the so-called ,pebidian as merely       
marking the duration of a volcanic      
period in early ,cambrian time4  ,it    
will thus be seen that according to my  
view the unmistakably pre-,cambrian     
rocks of ,britain consist of1 first and 
oldest1 the ,lewisian gneiss2 second1   
the ,torridonian sandstones and         
conglomerates4 ,the ,uriconian and      
,longmyndian formations may prove to be 
in part or in whole equivalents of the  
,torridonian4 ,the ,dalradian rocks have
 not yet had their position determined4 
,they may possibly mark a distinct      
pre-,cambrian series1 but it seems quite
 as probable that they are only a       
metamorphic complex in which ,archan1   
,torridonian and ,cambrian1 or even     
,lower ,silurian rocks are included4    
,sir ,archibald ,geikie1                
,director-,general of the ,geological   
,survey of ,great ,britain and ,ireland4

     ,,are ,,there ,,traces ,,of        
,,glacial ,,man ,,in ,,the ,,trenton    
,,gravels8   ,in a paper published in   
,science1 ,nov4 #be4 #ahib1 ,i undertook
 to study the evidence relating to      
paleolithic man in the eastern ,united  
,states from a new point of view1--that 
furnished by certain recently acquired  
knowledge of the contents of quarries   
and shops where modern aboriginal flaked
 implements were made4 ,it was shown    
that all rudely flaked forms could be   
sufficiently accounted for without the  
necessity of assuming a very rude state 
of culture1 and that any people1        
paleolithic or neolithic1 would in      
roughing out blades--the principal      
product of the flaking process--produce 
precisely these forms and in great      
numbers as refuse4 ,it further appeared 
that the finding of these objects in    
sporadic cases in glacial gravels or in 
any formation whatsoever1 could not be  
considered as proving or tending to     
establish the existence of a particular 

grade of stone-age culture for the      
region in which the formation occurs1   
since they may as readily pertain to a  
neolithic as to a paleolithic status4   
,it was conclusively shown that no      
worked stone that can with reasonable   
safety be called an implement has been  
reported from the gravels1 and that it  
is therefore clearly useless1 not to say
 unscientific1 to go on enlarging upon  
the evidence of an ,american paleolithic
 period and multiplying theoretic       
details of its culture4  ,i now propose 
to review briefly the question of the   
age of our so-called paleolithic        
implements1 the questions of the grade  
of a given feature of culture and of the
 age or chronologic place of that       
culture being very properly treated     
separately1 as they depend for their    
support upon distinct classes of        
evidence4 ,during the past summer1      
#ahib1 certain important items of new   
evidence have been discovered bearing   
upon the question of the occurrence or  

non-occurrence of rudely flaked stones  
or of any artificial objects whatsoever 
in the normal gravels of the ,delaware  
,valley1 and it therefore becomes       
necessary to examine somewhat critically
 such of the published evidence as seems
 to be seriously affected by these      
recent observations4  ,it may be stated 
in beginning that no one disputes the   
glacial age of the ,trenton gravels4    
,the question to be discussed is simply 
this1--is the evidence satisfactory that
 works of art have been found in these  
gravels8 ,nothing else need be asked or 
answered4 ,i do not take up this subject
 because ,i love controversy2           
disputation is really most distasteful  
to me4 ,it happens that under the       
,bureau of ,ethnology of the            
,smithsonian ,institution ,i have been  
assigned to the work of making a survey 
of the archeology of the ,atlantic coast
 region in which large areas1 especially
 in states south of ,mason and ,dixon's 
line1 remained almost untouched by      

investigators1 and two years have been  
consumed mainly in these southern areas4
 ,but there are questions that refuse to
 be confined to definite geographic     
limits1 and evidence secured in one     
section is sometimes found to bear so   
directly and forcibly upon problems     
pertaining primarily to other sections  
that the student of these problems must 
perforce become a free lance1 and       
unhesitatingly enter any province       
promising results of value1 howsoever   
fully occupied it may be by other       
investigators4 ,one of the most         
interesting and important questions     
growing out of the study of ,american   
archeology has1 as we have seen1 arisen 
in the ,delaware ,valley1 and the turn  
taken by some of my work in the south   
and west is such that ,i cannot pass    
this question by without consideration4 
,the necessity of taking up the subject 
of glacial man became more and more     
apparent as the years passed on1 and    
people continued to say to me1 ,you must

 go to ,trenton2 we are not satisfied   
with the present status of the question 
there2 the evidence arrayed in favor of 
the theory of a paleolithic gravel man  
needs critical examination4  ,the       
difficulty of taking up and re-examining
 evidence1 of which the record only     
remains1 is1 however1 very great1 since 
in most cases the evidence rests upon or
 consists of field observations1 and    
these cannot be recalled or repeated1   
and there is absolutely no means of     
testing directly the value of what is   
recorded4 ,one may seek either to verify
 or to discredit the promulgated        
theories1 but years of search may fail  
to produce a single new item of evidence
 bearing decisively upon the subject4   
,it is possible that at one period      
numerous finds of implements should be  
reported from certain portions of the   
gravels1 and that afterwards the whole  
remaining body of these formations      
should be worked over and searched      
without securing a trace of art2 yet    

this latter evidence1 being negative1   
need not necessarily be considered      
sufficient to overturn the original     
positive evidence if that happens to be 
of a high class4 ,there is not the least
 doubt1 however1 that positive evidence 
may be so impaired by various defects   
and inconsistencies1 that1 unsupported  
by renewed and well verified            
observations1 it will finally yield to  
the negative forces2 and if the theories
 of a gravel man in the eastern ,united 
,states1 howsoever fortified by         
accumulated observations1 are not really
 properly supported in every way1 they  
are bound in time to fall to the ground4
 ,all ,i can reasonably hope to do now  
is to have the evidence relating to     
glacial man placed on trial1 and so     
fully examined and cross-examined that  
those who accept gravel man need not    
longer do so blindly without knowing    
that there are two sides to the         
question1 and those who do not accept   
him may know something of the reasons   

for the belief that is in them4  ,the   
evidence employed to prove the presence 
of a race of men in the ,delaware       
,valley in glacial times is confined    
almost wholly to the alleged discovery  
of rude implements in the glacial       
gravels4 ,practically all the evidence  
has been collected by ,dr4 ,c4 ,c4      
,abbott1 and upon his skill as an       
observer1 his faithfulness as a         
recorder1 his correctness of judgment   
and his integrity of character1 the     
whole matter stands4 ,many visitors1 men
 of high repute in archeology and       
geology1 have visited the site1 but the 
observations made on such occasions     
appear not to have been of a nature to  
be of great value in evidence1 the finds
 being doubtful works of art or not     
having properly established             
relationships with the gravels in place4
 ,in the discussion of gravel man in    
eastern ,america a wide range of objects
 and phenomena has been considered1 but 
the real evidence1 upon which the theory

 of an ancient race and a peculiar      
culture must depend1 is furnished by a  
hundred pieces--more or less--of rudely 
flaked stones said to have come from the
 gravels in place4 ,and now what can be 
said with reference to this series of   
flaked stones further than that they are
 reported by the collector to have been 
found in the gravels at definite stated 
depths8 ,i have elsewhere shown that    
they are not demonstrably implements in 
any case1 that they are identical in    
every respect with the quarry-shop      
rejects of the ,american ,indian1 that  
they do not closely resemble any one of 
the well established types of ,european 
paleolithic implements1 and that they   
are not a sufficient index of a         
particular stage of culture4 ,i shall   
now present such reasons as there may be
 for the belief1 held by many1 that they
 were not really found in the           
undisturbed glacial gravels4  ,it is    
generally understood that the earliest  
reported gravel finds of importance were

 made on the banks of ,assanpink creek  
within the city limits of ,trenton1     
where the gravels to a thickness of     
twenty feet or more were exposed in a   
railway cutting4 ,later the river bluff 
near the lower end of the city1 where   
the gravels were exposed to a depth of  
from twenty-five to forty feet1 yielded 
large numbers4 ,these two sites1 so far 
as ,i can learn1 furnished at least     
three-fourths of the finds in place4    
,other specimens were found singly in   
slight natural exposures1 and in        
excavations for cellars1 sewers1 etc41  
at various points within the city       
limits4  ,the river bluff was for a     
considerable period the favorite hunting
 ground of the searchers for rudely     
flaked stones1 and many specimens were  
collected4 ,the gravels were exposed in 
a steep1 nearly straight bank1 several  
hundred yards in length1 the base of    
which was washed by the river4 ,there   
can be no question that ,dr4 ,abbott and
 others have found shaped objects of    

various classes upon and in the face of 
this river bluff1 and the visitor       
to-day1 although the bluff is now buried
 almost completely under city refuse1   
will hardly fail to find some rudely    
flaked form in the deeper gullies or    
upon the narrow river bank or beach at  
the base4 ,dr4 ,abbott explicitly       
states#a that he obtained certain of    
these specimens from the gravel         
outcrops1 and that they were not in     
talus formations1 but in undisturbed    
deposits4 ,how then is it possible to do
 otherwise than accept these statements 
as satisfactory and final8  #a ,abbott1 
,c4 ,c4 ,primitive ,industry1 pp4       
#dic-eaj4  ,illustration3 ,fig4 #a4     
,sketch map of the ,trenton bluff1      
showing the relation of the sewer trench
 to the implement yielding slope4444 a-b
 section line1 ,fig4 #b4  ,very         
recently1 however1 fortunate            
circumstances have brought the evidence 
furnished by this site again within our 
reach1 thus enabling us to re-open the  

discussion under favorable conditions4  
,what ,i had for some time desired to do
 in this case was1 what ,i had already  
done at ,piny ,branch1 ,d4 ,c41 and at  
,little ,falls1 ,minn41 to open a trench
 into the face of the bluff1 and thus   
secure evidence for or against the      
theory of a gravel man4 ,this measure   
was1 however1 rendered impracticable by 
the occupation of the bluff margin by a 
city street2 but it happened last summer
 that the city authorities1 desiring to 
improve the sanitary condition of the   
city1 decided to open a great sewer     
through this very bluff to get a lower  
outlet to the river4 ,a trench twelve   
feet wide and some thirty feet deep1 the
 full depth of the exposed gravels1 was 
carried along the bluff just inside of  
its margin1 opening out into the river  
at the point where the bluff turns      
toward the north-east4 ,it was a        
trenching more complete and more        
satisfactory than any of which ,i had   
ever dreamed4 ,at no point for the      

entire length of the bluff did the      
excavation depart more than forty feet  
from the line of the terrace face--from 
the upper margin of the slope upon which
 such plentiful evidence of a supposed  
gravel man had been obtained4 ,the      
accompanying map and section1 ,figs4 #a 
and #b1 will indicate the location of   
the trench1 and show the exact relations
 of the natural and artificial exposures
 of the gravels4  ,illustration3 ,fig4  
#b4 ,sections made by the river and by  
the sewer1 the former yielding many     
implements1 the latter yielding none4   
,i made several visits to the place1    
descended frequently into the great cut 
and examined the gravels and their      
contents with the utmost care1 but      
without securing a trace of art4        
,recognizing the vital importance of    
utilizing to the fullest extent this    
opportunity of testing the art-bearing  
nature of the gravels at this point1 ,i 
resolved to undertake a systematic study
 of the subject4 ,summoning my          

assistant1 ,mr4 ,william ,dinwiddie1    
from his field of operations in the     
,south1 ,i had him spend upwards of a   
month at the great trench1 faithfully   
watching the gravels as they were       
exposed4 ,mr4 ,dinwiddie had worked     
three years under my personal direction1
 and had helped open upwards of twenty  
trenches through similar gravel         
deposits1 and was therefore well        
qualified for the work4 ,prof4 ,w4 ,j4  
,mc,gee1 ,prof4 ,r4 ,d4 ,salisbury1 ,dr4
 ,stewart ,culin and ,dr4 ,abbott also  
visited the place one or more times     
each4 ,relics of art were found upon the
 surface and in such portions of the    
talus as happened to be exposed1 but    
nothing whatever was found in the       
gravels in place1 and the search was    
closed when it became fully apparent    
that the case was hopeless4  ,it may be 
claimed that the conditions under which 
gravels are exposed in trenching as it  
progresses1 are not as favorable for the
 collection of enclosed relics as where 

exposed by natural processes of         
weathering4 ,this is true in a certain  
measure1 as specimens may be obscured by
 the damp clinging sand which forms the 
matrix of the gravels4 ,this1 however1  
would interfere but little with the     
discovery of large flaked stones1 such  
as we were led to expect in this place1 
and this slight disadvantage in         
detecting shaped pieces in fresh        
exposures is more than over-balanced by 
the treachery of weathered surfaces     
which often give to intrusive objects   
the appearance of original inclusion4   
,the opportunity for studying the       
gravels in all their phases of bedding1 
composition and contents1 was really    
excellent1 and no one could watch the   
constantly renewed exposures hour after 
hour for a month without forming a most 
decided notion as to the implement      
bearing qualities of the formation4 ,not
 the trace of a flaked stone1 or of a   
flake or artificial fragment of any kind
 was found1 and we closed the work with 

the firm conviction that the gravels    
exposed by this trench were absolutely  
barren of art4 ,but ,dr4 ,abbott claims 
to have found numerous implements in the
 bluff face a few feet away and in the  
same gravels4 ,if this is true1 the     
conditions of glacial occupation of this
 site must have been indeed remarkable4 
,it is implied that during the whole    
period occupied by the melting of the   
ice sheet within the drainage of the    
,delaware valley the hypothetical rude  
race lived on a particular line or zone 
afterwards exposed by the river to the  
depth of #cj feet1 leaving his strange  
tools there by the hundreds1 while      
another line or zone1 not more than     
forty feet away at most1 exposed to the 
same depth by an artificial trench1 was 
so avoided by him that it does not      
furnish the least memento of his        
presence4 ,one vertical slice of the    
gravels twelve feet thick does not yield
 even a broken stone1 while another     
slice not probably one-half as thick1   

cut obliquely through the gravels near  
by1 has furnished subject-matter for    
numerous books and substantiation for a 
brace of theories4 ,that no natural line
 of demarcation between the two section 
lines is possible1 is shown by the fact 
that the formations are continuous1 and 
that the deposits indicate a constant   
shifting of lines and areas of          
accumulation2 thus it was impossible for
 any race to dwell continuously upon any
 spot1 line or plane4 ,this is well     
shown in the section1 ,fig4 #c1 which   
gives the relations of the art-producing
 section of ,dr4 ,abbott to the         
non-art-producing section of the sewer4 
,the gravels were laid down entirely    
irrespective of subsequent cutting1     
natural or artificial2 yet we are       
expected to believe that a so-called    
gravel man could have resorted for a    
thousand years to the space a1 leaving  
his half shaped or incipient tools at   
all stages of the gravel building from  
base to top1 failing entirely to visit a

 neighboring space b1 or to leave there 
a single flake to reward the most       
faithful search4 ,it is much easier to  
believe that one man should err than    
that a guileless race should thus       
conspire with a heartless nature to     
accomplish such extraordinary results4  
,the easier explanation of the whole    
matter is that the objects found by ,dr4
 ,abbott were not really in the gravels1
 but that they are ,indian shop-refuse  
settled into the old talus deposits of  
the bluff1 and that his eager eyes1     
blinded by a prevailing belief in a     
paleolithic man for all the world alike1
 failed to observe with their wonted    
keenness and power4  ,illustration3     
,fig4 #c4 a1 ,reputed implement         
producing zone of the river front4 b1   
,barren zone of sewer4  ,but this case  
does not stand alone4 ,the first        
discoveries of supposed gravel          
implements are said to have been made   
when the ,pennsylvania ,railway opened a
 road bed through the creek terrace on  

the site of the present station4 ,at    
first numerous specimens of rudely      
flaked stones were reported1 and the    
locality became widely known to         
archeologists1 but the implement bearing
 portions of the gravels--and this is a 
most significant fact--were limited in  
extent1 and the deposit was soon        
completely removed1 the horizontal      
extension containing nothing4 ,at       
present there are excellent exposures of
 the full thickness of the gravels at   
this point1 but the most diligent search
 is vain1 the only result of days of    
examination being a deep conviction that
 these gravels are and always were      
wholly barren of art4  ,it thus appears 
that here as well as upon the river     
front1 the works of art were confined to
 local deposits1 limited horizontally   
but not vertically1 and a strong        
presumption is created that the finds   
were confined to redistributed gravels  
settled upon the terrace face in the    
form of talus4 ,dr4 ,abbott states that 

at that point where ,i gathered the     
majority of specimens there is a want of
 stratification4#b ,it is well known    
that such rearranged deposits are often 
difficult to distinguish from the       
original gravels4 ,in trenching an      
implement producing terrace at          
,washington--where the conditions were  
probably quite similar to those at the  
,trenton railroad station--,i passed    
through eighty feet of redistributed    
talus gravels before encountering the   
gravels in place1 and so deceptively    
were portions of these deposits re-set  
that experts in gravel phenomena were   
unable to decide whether they were or   
were not portions of the original       
formation 7cretaceous74 ,the question   
was finally settled by the discovery of 
artificially shaped stones in and       
beneath the deposits4  #b ,abbott1 ,c4  
,c4 #ajth ,annual ,report of the        
,peabody ,museum1 p4 #da4  ,again1 an   
implement bearing deposit of gravel was 
recently discovered by the late ,miss   

,f4 ,e4 ,babbitt at ,little ,falls1     
,minnesota1 and sufficient 7a very      
little7 digging was done to satisfy the 
discoverer1 and all paleolithic         
archeologists as well1 that the objects 
were really imbedded in the glacial     
gravels4 ,in the summer of #ahib ,i     
visited the place and carried a trench  
twenty feet horizontally into the       
terrace face on the implement bed level 
before encountering the gravels in      
place4 ,the talus deposits were several 
feet thick1 and were of such a nature   
that their true character could not be  
determined without careful and extensive
 trenching4 ,the whole talus deposit was
 here well stocked with ,indian quartz  
quarry-shop rejects1 which were as usual
 of paleolithic types1 and it was but   
natural that ,miss ,babbitt's           
conclusions1 although based as they     
necessarily were upon inexpert          
observations1 backed by such well known 
types of implements should be           
unhesitatingly accepted by believers4   

,the occurrence of these telling        
examples of the deceptive appearance of 
re-set gravels would seem to justify and
 emphasize the conviction created by a  
critical examination of the two leading 
so-called paleolithic sites at ,trenton1
 that ,dr4 ,abbott1 notwithstanding his 
asseverations to the contrary1 has been 
deceived4 ,very strong support1 it seems
 to me1 is given to this conclusion by  
the recently published opinion of the   
late ,dr4 ,h4 ,carvill ,lewis1 a        
glacialist familiar with the ,trenton   
region1 and with the work of ,dr4       
,abbott at the period of his paleolithic
 castle building4 ,dr4 ,lewis is        
reported to have maintained before an   
open meeting of the ,academy of ,science
 in ,philadelphia that what ,dr4 ,abbott
 believed to be undisturbed layers 7of  
gravel7 were those of an ancient        
talus4#c ,this remark may refer to both 
the main sites--the one at the railroad 
station and the other at the river      
front--or possibly only to the former4  

,i have also heard it stated that that  
eminent scholar1 ,dr4 ,leidy1 who must  
have had ample opportunities of forming 
correct opinions upon the subject1 held 
pretty much the same views of ,dr4      
,abbott's finds4  #c ,brinton1 ,d4 ,g41 
,science1 ,oct4 #bh1 p4 #bdi4           
,illustration3 ,fig4 #d4 ,a freshly     
formed gravel bluff4  ,illustration3    
,fig4 #e4 ,early stage of talus         
formation4  ,illustration3 ,fig4 #f4 ,an
 ancient talus4  ,to make the above     
criticism entirely clear1 a few words of
 explanation of talus phenomena may be  
added4 ,as a river cuts its channel     
deeper and deeper into deposits of      
gravel a section is gradually exposed1  
but the gravels break down readily under
 atmospheric influences and the exposed 
face does not retain a high angle4 ,the 
upper part crumbles and descends toward 
the base1 there to rest against the     
slope or to be carried away by the      
stream4 ,a supposititious case will be  
convenient for illustration4 ,a gravel  

terrace twenty feet in height is        
encroached upon by the river at high    
water and undermined1 and the face      
breaks down vertically1 leaving an      
exposure as illustrated in ,fig4 #d4 ,in
 a very short time the upper portions   
become loosened and fall below1 giving a
 steep slope as seen in ,fig4 #e4 ,the  
process goes on with gradually          
decreasing rapidity1 and if the river   
does not again encroach seriously1 a    
practically stable slope is reached1 as 
shown in ,fig4 #f4 ,such a talus may be 
hundreds or even thousands of years old1
 but there is rarely any means of       
determining its exact age4 ,if the      
gravels are homogeneous in character1   
the talus will simulate their normal    
condition so completely that the        
distinction cannot be made out in       
ordinary gullies or by unsystematic     
digging4 ,if the gravels contain varied 
strata the talus will be composite1 and 
will be more readily distinguished from 
at least portions of the material in    

place4  ,now it is important to observe 
what may be the possible art contents of
 such a talus as that shown in ,fig4 #f4
 ,it may contain all objects of art     
originally included in that portion of  
the gravels represented by a1 b1 c1     
together with all articles that happened
 to be upon the surface b1 c1 beside    
such objects as may have accumulated    
from dwelling or shop work upon its own 
surface1 after the slope became         
sufficiently reduced to be occupied for 
these purposes4 ,a talus is therefore   
liable to contain1 and in the utmost    
confusion1 relics of all periods of     
occupation1 supposing always that there 
were such periods1 from the beginning of
 the formation of the gravel deposits   
down to the present moment4 ,as a rule  
such a talus1 if art-containing1 will   
have a large percentage of shop and     
quarry-shop refuse1 for the reason that 
the exposed gravels1 and the banks and  
beds of rivers cutting them1 furnish1 as
 a rule1 a good deal of the raw material

 utilized by workers in stone1 and the  
shops in which the work was done are    
usually located upon the slopes and     
outer margins of the terraces4 ,although
 there is the possibility of very       
considerable age for these talus        
deposits1 it is unlikely that any of    
them date back as far as the close of   
the glacial epoch or at all near it1 for
 rivers change back and forth           
constantly1 undermining first one bank  
and then the other1 so that a very large
 percentage of our talus deposits have  
been formed well within the historic    
period4  ,at ,trenton the constantly    
exposed gravel banks afforded           
considerable argillite in bowlders1     
fragments and heavy masses1 as well as  
some other flakable stones of inferior  
quality little used1 and it is          
inevitable that the ,indian who dwelt   
upon the shores of the river should have
 sought the workable pieces along the   
bluff1 leaving the refuse everywhere2   
and it is a necessary consequence that  

the terrace margin1 the bluff face1 and 
the talus deposits1 places little fitted
 for habitation1 should for long        
distances contain no trace of any art   
shapes save such as pertain to          
manufacture4 ,thus are fully and        
satisfactorily accounted for all the    
turtle backs and other rude forms that  
our paleolith hunters have been so      
assiduously gathering4 ,nothing can be  
more fully apparent than that no other  
race than the ,indian in his historic   
character and condition need be conjured
 up to reasonably account for every     
phase and every article of the recovered
 art4 ,mistaken interpretations of the  
nature of shop rejects1 and the common  
association of these objects with       
redistributed gravels1 are probably     
accountable for the many misconceptions 
that have arisen4 ,talus deposits form  
exceedingly treacherous records for the 
would-be chronologist4 ,they are the    
reef upon which more than one           
paleolithic adventurer has been wrecked4

  ,relics of art attributed to gravel   
man have been collected1 so far as ,i   
can gather from museum labels and from  
incidental references in various        
publications1 from a number of sites    
aside from the two already referred to4 
,these are scattered over the city1 and 
the finds were made mostly in exposures 
of the gravels that remained visible for
 a short time only1 as in street and    
cellar excavations and well pits4 ,these
 reported finds can never be brought    
within the range of re-examination1 and 
the searcher after unimpeachable        
testimony must content himself with     
placing them in the doubtful column on  
general principles4 ,urban districts are
 so subject to disturbance through      
cutting down of hills1 filling in of    
depressions1 grading of streets1 digging
 of foundations1 cellars1 sewers1 wells 
and graves that no man can1 from a      
limited exposure such as those producing
 the reported tools necessarily were1   
speak with certainty of the undisturbed 

nature of the deposits penetrated4 ,it  
is doubtful if any one is justified in  
publishing such observations at all     
without serious query4 ,such testimony  
is liable to fall of its own inherent   
weakness1 being absolutely valueless if 
unsupported by collateral evidence of   
real weight4 ,it can only be made       
permanently available to science by the 
discovery of something unusual or unique
 with which to couple it1 something     
decidedly un-,indian in character or    
type1 as for example the two skulls now 
in the ,peabody ,museum4 ,these objects 
and the antler knife-handle exhibited   
with them may be alluded to as the only 
finds so far made at ,trenton1 having of
 themselves the least potentiality as   
proof and these skulls and this         
knife-handle must yet be subjected to   
the rigid examination made necessary by 
the importance of the conclusions to be 
based upon them4  ,something may now be 
said concerning the art remains upon    
which this discussion hinges1 and upon  

which conclusions of the greatest       
importance to anthropology are supposed 
to depend4 ,let us pass over all that   
has been said with regard to their      
manner of occurrence and association    
with the gravels and ask them simply    
what story they tell of themselves4     
,does this story1 so far as we are able 
clearly to read it1 speak of a great    
antiquity and a peculiar culture1 or    
does it hint rather at vital weaknesses 
in the position taken by the advocates  
of these ideas8 ,we shall see4 ,the     
history of the utilization of rudely    
flaked stones in the attempt to         
establish a gravel man in ,america has  
never been written1 but as read between 
the lines of paleolithic literature1 it 
runs about as follows3 ,the theory of a 
very rude and ancient people1 having a  
unique culture and certain peculiar art 
limitations1 was developed in ,europe   
many years ago in a manner well known   
and often rehearsed4 ,this people was   
associated with the ice age in ,europe1 

and this epoch1 with its moraines and   
till and sedimented gravels1 was found  
to have been repeated in ,america4 ,it  
was the most natural thing possible that
 these discoveries should carry with    
them the suggestion that man may have   
existed here as in ,europe during that  
epoch1 and that his culture was of      
closely corresponding grade4 ,these were
 legitimate inferences and warranted the
 instituting of careful researches1 but 
it was a dangerous suggestion to put    
into the minds of enthusiastic novices  
with fertile brains and ready pens4 ,the
 idea was hardly transplanted to        
,american soil before finds began to be 
made4 ,the so-called types of ,european 
paleoliths suggested the lines upon     
which finds here should be made1 and    
everything in the way of flaked stones  
connected directly or indirectly with   
the glacial gravels which had not yet   
been fully credited to and absorbed by  
the inconvenient ,indian1 was seized    
upon as representing the ancient time   

and its hypothetic people and culture4  
,in the early days of the investigation 
the various rude forms of flaked stones1
 resulting from failures in manufacture1
 had not been studied1 and were shrouded
 in convenient mystery1 and they thus   
became the foundation of the new        
archeologic dynasty in ,america1 the    
dynasty of the turtle-back4 ,dr4 ,abbott
 states in his first work#d that these  
rude implements are not especially      
characteristic of any one locality1 but 
seem to be scattered uniformly over the 
state4 ,specimens of every type1 he     
says1 are found upon the surface1 and   
are plowed up every spring and autumn2  
but this in no way militates against the
 opinion that these ruder forms are far 
older than the well-chipped jasper and  
beautifully-polished porphyry           
stone-work4#e ,at that stage of the     
investigation it was not at all         
necessary that a specimen should come   
from the gravels in place or from any   
given depth1 since the type was supposed

 to be easily recognized and was a      
sufficient means of settling the        
question of age4  #d ,abbott1 ,c4 ,c4   
,the ,stone ,age in ,n4 ,j41 ,sm4 ,rep4 
#ahge1 p4 #bdg4  #e ,ibid1 p4 #beb4     
,rude implements were called for and    
they were found4 ,the only requirements 
were that they should not be of         
well-known ,indian types1 that they     
should be rude and have some sort of    
resemblance to what were known as       
paleolithic implements abroad4 ,since   
most of these so-called gravel          
implements of ,europe are also doubtless
 the rejects of manufacture resemblances
 were readily found4 ,the early attempts
 to utilize these rejects in support of 
the theory1 and make them masquerade    
creditably as implements with           
specialized features and self-evident   
adaptation to definite ice-age uses1 now
 appear decidedly amusing4 ,gradually1  
however1 the lines have been drawn upon 
this early license1 and it is to-day    
well understood by all careful students1

 that since the rude forms are so often 
repeated in modern neolithic refuse1 the
 only reliable test of a gravel         
implement is its occurrence in the      
gravels in place4 ,that a particular    
implement1 said to have been obtained   
from the gravels1 is of paleolithic     
type1 does not in the least strengthen  
its claims to being a bona fide gravel  
implement2 nor does its easy assignment 
to a type give any additional value to  
the collector's claim that the gravels  
said to contain it are implement        
bearing4 ,the very names1 rude          
implement1 paleolithic implement1 etc41 
carry with them a certain amount of     
mysterious suggestion2 one thinks of    
unique1 significant shapes and of       
strange1 archaic uses4 ,at their mere   
mention1 the great ice sheet looms up   
with startling realism1 and the reindeer
 and the mighty mammoth appear upon the 
scene4 ,the reader of our paleolithic   
literature is led to feel that these    
antiquated objects carry volumes of     

history in their worn and weather-beaten
 faces1 but this is all the figment of  
fertile brains4 ,these objects have     
without exception the appearance of the 
most commonplace every-day rejects of   
manufacture without specialization and  
without hidden meaning4 ,they tell of   
themselves no story whatsoever1 save    
that of the oft-repeated failure of the 
aboriginal blade maker in his struggle  
with refractory stones4 ,this will be   
shown with greater clearness farther on4
  ,but the scheme does not end with the 
repetition of a ,european state of      
affairs4 ,our gravel archeologists have 
not been content to adopt that feature  
of the foreign scheme which utterly     
destroys the paleolithic race before a  
higher culture is brought upon the      
scene4 ,it was thought to improve upon  
the borrowed plan by allowing for a     
gradual development upward from the     
paleolithic stage1 represented          
exclusively by a class of meaningless   
bits of flaked stone1 through a period  

less rude1 characterized by productions 
so far advanced as to be assigned to a  
definite use4 ,these latter productions 
consist mainly of rather large and often
 rude blades1 sometimes plain1 but      
generally notched or modified at the    
broader end as if to be set in a handle1
 or attached to a spear or arrow shaft4 
,these were assigned to post-glacial    
times in such a way as to bridge or     
partly bridge the great space between   
the glacial epoch and the present4 ,they
 were separated arbitrarily from the    
body of the collections of the region1  
and referred to as probably the work of 
an ,eskimo race4 ,this arrangement      
produced a pleasing symmetry and        
completeness1 and brought the history of
 man down to the beginning of the       
,indian epoch1 which is represented by  
all of those forms of art with which the
 red man is historically associated4    
,three principal periods are thus       
thought to be represented by the finds  
at ,trenton2 and in the arrangement of  

the collections these grand divisions   
are illustrated by three great groups of
 relics1 which are looked upon by the   
founders of the scheme as an epitome of 
native ,american art and culture4 ,by   
others this grouping is looked upon as  
purely empirical1 as an arbitrary       
separation of the normal art remains of 
the historic ,indian1 not suggested by  
anything in the nature or condition of  
the objects1 nor in the manner of their 
discovery4  ,the ,eskimo feature of the 
scheme requires a more detailed         
examination than can be given it here4  
,it may be stated1 however1 that the    
separation of the so-called ,eskimo     
spear points1 or whatever they may be1  
from the great body of associated       
articles of flaked stone1 appears to be 
a highly arbitrary proceeding4 ,that    
they were extensively made by the       
,indians is proved by the occurrence of 
refuse resulting from their manufacture 
on modern shop sites1 and that they were
 used by the ,indian1 is equally        

apparent from their common occurrence on
 modern dwelling sites4 ,the            
exceptionally large size of the         
argellite points is readily accounted   
for by the nature of the material4 ,it  
was the only stone of the region well   
adapted to the manufacture of long      
blades or projectile points4 ,jasper1   
quartz and flint have such minute       
cleavage that1 save in rare cases1 small
 implements only could be made from     
them4 ,their peculiar manner of         
occurrence1 described at so much length 
by ,dr4 ,abbott1#f has been given undue 
consideration and weight4 ,the phenomena
 observed may all be accounted for as a 
result of the vicissitudes of aboriginal
 life and occupation within the last few
 hundred years as fully and             
satisfactorily as by jumping thousands  
of years backward into the unknown4  #f 
,abbott1 ,c4 ,c4 ,popular ,science      
,monthly1 ,dec41 #ahhi4  ,whatsoever    
real support there may be for the       
,eskimo theory1 either in the published 

or the unpublished evidence1 it is      
apparent that under the present system  
of solitary and inexpert research1 the  
scientific world will gain little that  
it can utilize without distrust and     
danger4 ,whatsoever may be the final    
outcome--which outcome is bound to be   
the truth--it is clear that there is    
little in the present evidence to       
warrant the separation of a paleolithic 
and an ,eskimo period of art from that  
of the ,indian4  ,that the art remains  
of the ,trenton region are essentially a
 unit1 having no natural separation into
 time1 culture or stock groups1 is      
easily susceptible of demonstration4 ,i 
have already presented strong reasons   
for concluding that all the finds upon  
the ,trenton sites are from the surface 
or from recent deposits1 and that all   
may reasonably be assigned to the       
,indian4 ,a find has recently been made 
which furnishes full and decisive       
evidence upon this point4 ,at ,point    
,pleasant1 on the ,delaware1 some       

twenty-five miles above ,trenton1 there 
are outcrops of argillite1 and here have
 been discovered recently the shop sites
 upon which this stone was worked4      
,there are two features of these shops  
to which the closest attention must be  
given4 ,the first is that they are      
manifestly modern2 they are situated on 
the present flood plain of the          
,delaware1 and but a few feet above     
average water level1 the glacial terrace
 here being some forty or fifty feet in 
height4 ,these shops1 therefore1        
represent the most modern phases of     
aboriginal industry1 and may have been  
occupied at the coming of ,william      
,penn4 ,the second point is that every  
type of flaked argillite found in the   
,trenton region1 associated with the    
gravels or otherwise1 is found on this  
site4 ,it was to a certain extent a     
quarry site1 for the great masses of    
argillite brought down by the floods    
were here broken up and removed from the
 river banks or bed4 ,it was a shop     

site1 for here the articles1 mainly     
blades1 were roughed out1 and it was    
also a dwelling place--a village        
site--where all the specialized forms of
 flaked stones made from the blades were
 prepared for use4 ,here are found great
 numbers of the rude failures1          
duplicating every feature of the        
mysterious paleolith with which our     
museums are stocked1 and exhibiting the 
same masterly quitting at just the point
 where no further shaping was           
possible4#g ,here we see the same boldly
 manipulated cutting edge1 the flat     
bottom and high peak1 and the same      
mysteriously weathered and disintegrated
 surfaces1 so skillfully made1 by a nice
 balancing of accidents1#h to tell the  
story of chronologic sequence in        
deposition4  #g ,abbott1 ,c4 ,c4        
,smithsonian ,report1 #ahge1 p4 #bdh4   
#h ,ibid4 ,primitive ,industry1 p4 #dhg4
  ,beside the failures1 we have here1 as
 on other quarry shop sites1 the        
evidence of more advanced work1 the     

wide1 thick1 defective blades1 and many 
of the long1 thin blades broken at or   
near the finishing point4 ,here1 too1   
just back of the roughing-out shops1 are
 the dwelling sites from which many     
specialized forms are obtained4 ,the    
,eskimo type is fully represented as    
well as the ordinary spear point1 the   
arrow point1 and the perforator of our  
,indian4 ,there is not a type of flaked 
argillite known in the ,delaware valley 
that may not be duplicated here on this 
modern ,indian site1 and this has been  
known by local archeologists for years4 
,why so little has been said about the  
matter is thus explained4 ,dr4 ,abbott1 
in #ahij1 discovering this site1 and    
finding typical paleolithic implements  
7the ordinary ruder forms of rejects7   
among the refuse1 was so entirely at a  
loss to explain the occurrence that he  
felt compelled to again take up the     
examination of the gravel deposits of   
the valley of the ,delaware with the    
hope of finally solving the problem4#i  

,the true conditions would have been at 
once apparent to any one not utterly    
blinded by the prevailing               
misconceptions4  #i ,abbott1 ,c4 ,c4    
,annual ,report of the ,curator of the  
,museum of ,american ,archeology1       
,university of ,pennsylvania4 ,no4 #a1  
p4 #g4  ,the entire simplicity of the   
archeologic conditions in the ,delaware 
valley may be further illustrated4 ,had 
,william ,penn paused in his arduous    
traffic with the tawny ,delawares1 and  
glanced out with far-sighted eyes from  
beneath the pendant branches of the     
great elm at ,shackamaxon1 he might have
 beheld an uncouth savage laboriously   
fabricating rude ice age tools1 making  
the clumsy turtle-back1 shaping the     
mysterious paleolith1 thus taking that  
first and most interesting theoretical  
step in human art and history4 ,had he  
looked again a few moments later he     
might have beheld the same tawny        
individual deeply absorbed in the task  
of trimming a long rude spear point of  

,eskimo type from the refractory        
argillite4 ,if he had again paused when 
another handful of baubles had been     
judiciously exchanged1 he would have    
seen the familiar redskin carefully     
finishing his arrow points and fitting  
them to their shafts preparatory to a   
hunting and fishing cruise on the placid
 ,delaware4 ,thus in a brief space of   
time ,penn might have gleaned the story 
of the ages--the history of the         
turtle-back1 the long spear point and   
their allies--as in a single sheaf4 ,but
 the opportunity was wasted1 and the    
heaps of flinty refuse left upon the    
river bank by the workmen were the only 
record left of the nature of the work of
 that day4 ,two hundred years of        
aboriginal misfortune and ,quaker       
inattention and neglect have resulted in
 so mixing up the simple evidence of a  
day's work1 that it has taken           
twenty-five years to collect the        
scattered fragments1 to sift1 separate  
and classify them1 and to assign them to

 theoretic places in a scheme of culture
 evolution that spans ten thousand      
years4  ,yet is there really nothing in 
it all1 in the theories1 the            
observations1 the collections and the   
books8 ,do ,i speak too positively in   
condemnation of the results of years of 
earnest investigation8 ,perhaps so1 but 
the voluminous testimony is so          
overloaded with inaccuracies1 the relics
 of unscientific method and misleading  
hypotheses1 that every item must be     
sharply questioned2 and the conclusions 
reached so far overstep the limits      
warranted by the evidence1 that heroic  
measures alone can be effectual in      
determining their exact value4 ,if1 as  
many believe1 vital errors have been    
embodied in the evidence presented by   
the advocates of the theory1 it is      
impossible to state the case too        
strongly4 ,error once fully absorbed    
into the literature of science has many 
advantages over the tardy truth2 it is  
strongly fortified and must be attacked 

and exposed without fear or favor4      
,truth involved with it cannot          
permanently suffer4 ,if the twin        
theories of a gravel and a paleolithic  
man in eastern ,america are to be       
assailed as unsound or as not properly  
supported1 it should be done now while  
the originators and upholders are alive 
and alert to sustain their positions or 
to yield to the advances of truth4 ,i do
 not wish to wrongly characterize or to 
unduly minimize the evidence brought to 
bear in favor of these theories4 ,i do  
intend1 however1 to assist the world so 
far as possible in securing an exact    
estimate of all that has been said and  
done1 and all that is to be done4  ,in a
 previous article ,i have examined the  
evidence relating to paleolithic art in 
the eastern ,united ,states1 and have   
indicated its utter inadequacy and      
unreliability4 ,in this paper the       
testimony relating to the occurrence of 
gravel art1 in the locality most fully  
relied upon by advocates of the theory1 

has been partially reviewed and         
subjected to the strong light of recent 
observations4 ,it is found that the     
whole fabric1 so imposing in books and  
museums1 shrinks away surprisingly as it
 is approached4 ,the evidence furnished 
by the bluff face and by the railway    
cutting1 the two leading sites1 is      
fatally weakened by the practical       
demonstration of the fact that the      
gravels proper are at these points      
barren of art remains4 ,in endeavoring  
to naturalize an immigrant hypothesis1  
our gravel searchers1 unacquainted with 
the true nature of the objects collected
 and discussed1 and little skilled in   
the observation of the phenomena by     
means of which all questions of age must
 be determined1 have undoubtedly made   
grievous mistakes and have thus misled  
an expectant and credulous public4  ,the
 articles themselves1 the so-called     
gravel finds1 when closely studied are  
found to tell their own story much more 
fully and accurately than it has        

heretofore been read by students of     
archeology4 ,this story is that the art 
of the ,delaware valley is to all       
intents and purposes a unit1 that there 
is nothing unique or especially         
primitive or ancient and nothing        
un-,indian in it all4 ,all forms are    
found on demonstrably recent sites of   
manufacture4 ,the rude forms assigned by
 some to glacial times are all          
apparently wasters of ,indian           
manufacture4 ,the large blades of       
,eskimo type are only the larger blades1
 knives and spear points of the ,indian1
 separated arbitrarily from the body of 
the art-remains to subserve the ends of 
a theory1 certain obscure phenomena of  
occurrence having been found to give    
color to the proceeding4 ,to place any  
part of this art1 rude or elaborate1    
permanently in any other than the       
ordinary ,indian category will take     
stronger proofs than have yet been      
developed in the region itself4  ,the   
question asked in the beginning1 ,are   

there traces of glacial man in the      
,trenton gravels8 if not answered       
decisively in the negative1 stands      
little chance1 considering present      
evidence1 of being answered in the      
affirmative4 ,in view of the fact that  
numerous observations of apparent value 
have been made in other sections1 there 
is yet sufficient reason for letting the
 query stand1 and we may continue to    
cherish the hope that possibly by       
renewed effort and improved methods of  
investigation1 something may yet be     
found in the ,trenton gravels clearly   
demonstrative of the fascinating belief 
in a great antiquity for the human race 
in ,america4  ,the evidence upon which  
paleolithic man in ,america depends is  
so intangible that1 unsupported by      
supposed analogies with ,european       
conditions and phenomena1 and by the    
suggestions of an ideal scheme of       
culture progress1 it would vanish in    
thin air2 and if the theory of a glacial
 man can summon to its aid no better    

testimony than that furnished by the    
examples examined in this paper1 the    
whole scheme1 so elaborately mounted and
 so confidently proclaimed1 is in       
imminent danger of early collapse4      
,w4 ,h4 ,holmes4     ,,geology ,,as ,a  
,,part ,,of ,a ,,college ,,curriculum4  
,the demand for scientific studies as a 
part of the college curriculum is felt  
by all those who have to do with the    
provision of higher instruction for     
,american youth4 ,the reasons for this  
may be various1 but a fundamental reason
 is found in the tendency among the     
,american people in particular1 and in  
this age in general1 toward practicality
 in all things4 ,applied to education   
this practicality asks for a training   
which shall have a direct bearing upon  
the business of life to be followed     
immediately after the training period is
 ended4 ,it means a differentiation of  
subjects and specialization in methods  
to adjust the education to the different
 functions which the students taking it 

are preparing for4 ,it calls for a      
professional education for those who    
expect to become lawyers1 doctors1      
ministers1 or teachers1--a technical    
education for those who are to engage in
 the arts of the mechanical or civil    
engineer1 or of the architect4 ,it      
results not only in the establishment of
 colleges and universities devoted to   
this kind of education1 but it affects  
the methods of the high schools and     
academies1 and is felt down to primary  
schools1 and on the other hand the older
 institutions founded on a different    
plan are adapted to the popular demand  
by the addition to the regular studies  
of electives1 chosen not always for     
their value or disciplinary studies1 but
 because of the practical applicability 
of the information to be derived from   
them1 to the business of the student4   
,without discussing the relative merits 
of the two ideas of education1 the chief
 contrast between them may be found in  
the character of the results sought4    

,the knowledge of things and their uses 
is of chief importance in the practical 
education2 the knowledge of ideas and   
skill in their use is the aim of the    
liberal education4 ,geology is one of   
the sciences which most men will at once
 classify as among the practical        
sciences4 ,it deals with matters of     
practical importance to everybody4      
,coal1 iron1 the metals1 silver1 gold1  
tin1 lead1 building stone1 sand1 clay1  
petroleum1 and natural gas1 and all     
geological products are essential       
materials of modern civilization1 and a 
knowledge of them and of their modes and
 places of occurrence is one of the     
requisites of an education1 either from 
the practical or the liberal point of   
view4 ,so too the dynamics of           
atmospheric and hydraulic erosion1 the  
agency of rivers and oceans in          
destruction1 removal and reconstruction 
of geological formations have their     
eminently practical bearings upon the   
various arts of engineering4 ,while the 

practical value of geology is thus      
evident and undisputed1 it is not on    
this account that its importance as a   
part of a college course of education is
 urged4 ,as a practical study geology   
becomes the centre of a group of studies
 requiring years for mastery4 ,chemistry
 and physics are primarily essential to 
a full understanding of the most common 
of geological problems4 ,and to use     
geological facts and phenomena1 an      
acquaintance with the complex methods of
 engineering1 civil and mechanical1     
which again call for a thorough mastery 
of mathematics1 is necessary4           
,mineralogy and petrography1 metallurgy 
and mining engineering have each reached
 a stage of development entitling them  
to the rank of separate sciences1 but   
the practical training of the geologist 
should include them all4 ,when we add   
the biological sciences connected with  
historical geology1 paleontology1 zology
 and botany1 with all the laboratory and
 field work required for their proper   

study1 we have a group of affiliated    
branches of learning requiring four or  
five years of continuous study after the
 student has learned how to study4 ,it  
is plain therefore that only a          
specialist1 one who is willing to       
neglect other studies1 or who has       
previously had a liberal training1 can  
perfect himself on the practical side in
 the science of geology4  ,but          
irrespective of its practical uses1 as a
 means of training and supplementary to 
the ordinary studies of a college       
curriculum1 geology is one of the most  
useful of the sciences of observation4  
,it is in providing that particular     
training to which ,president ,eliot has 
recently called attention in the ,forum 
7,dec41 #ahib1 ,wherein ,popular        
,education ,has ,failed71 that geology  
can be used to such advantage4 ,speaking
 particularly of the lower education1   
,president ,eliot says it is the        
judgment and reasoning powers that      
particularly require attention4 ,their  

systematic development is to be attained
 in the four directions of observing    
accurately1 recording correctly1        
comparing1 grouping and inferring       
justly1 and expressing cogently the     
results of these mental operations4 7p4 
#dba47 ,the attainment of these ends is 
one of the purposes of liberal          
education1 whether it be in the primary 
school or in the university4 ,and       
geology1 or any other science1 is of    
value in a college course in proportion 
to its fitness for the exercise and     
development of these functions of the   
student4 ,geology may be taught without 
regard to these ends1 and then it is    
valuable from the practical point of    
view1 but when we examine it in respect 
of its availability as a disciplinary   
study we find it offering particular    
attractions4  ,using the distinction    
between theory and practice1 which is as
 old as ,aristotle1 geology in its      
theoretical aspect is more easily       
comprehended than is the theoretical    

aspect of most of the modern sciences4  
,this arises first from the fact that   
the facts and phenomena are of a simple 
and grand nature1 making it possible for
 the teacher to direct certain attention
 to the specific facts under            
consideration4 ,the water of the rivers1
 the mud by the road side1 the rocks and
 sands on the shore are familiar objects
 to all1 and it is a simple matter to   
call attention by ordinary language to  
the specific facts regarding them1      
which1 analyzed out1 are to form the    
basis of exact ideas and scientific     
definition and classification4 ,geology 
is the one science among the natural    
sciences which may begin with the common
 language of the pupil1 and by means of 
such language alone may build up ideas  
of precise phenomena in scientific      
terms4 ,physiography or physical        
geography surpasses geology proper in   
this particular1 as the admirable work  
of ,professor ,davis is showing1 and on 
this account it is the best introduction

 to geology4 ,but the very largeness and
 indefiniteness of the facts are in the 
way of the use of physical geography for
 the exercise of the finer and more     
exact functions of observation4 ,the    
disciplinary value of classics and      
mathematics is to a considerable extent 
derived from this quality1 the precision
 with which the words or figures kindle 
like ideas4 ,so long as the object of   
the training is to teach the knowledge  
of ideas and how to use them1 classics  
and mathematics are the simplest and    
purest means of developing a liberal    
education4 ,the addition of sciences to 
the college course is not because of the
 usefulness of the knowledge of things  
thus to be gained1 but because the      
language of the sciences is essential to
 call forth the observation and the     
exercise of the accompanying mental     
operations4  ,when it comes to dealing  
with the ideas associated with          
particular sense-observation1 where form
 or motion can not be expressed in      

simple mathematical terms1 language can 
not communicate a new idea or kindle it 
in another mind with precision4 ,it is  
necessary by some means to recall or to 
present the object itself to the        
student4 ,in the teaching of science    
this point is of great importance1 and  
much of the unsatisfactoriness of       
science-teaching is doubtless due to    
failure to note it4 ,no circumlocution  
of words can arouse in another or       
communicate to him the idea appropriate 
to a sensation he has never felt4 ,the  
blind man whose eyes are opened sees men
 as trees walking4  ,in the use of      
science for elementary training 7and the
 training is elementary until the       
student is capable of investigating and 
interpreting the facts and phenomena of 
a science directly7 that science is the 
better which deals with objects which   
are simple1 common and easily observed4 
,such is geology in some of its aspects4
 ,every time the student walks in the   
country he sees the facts discussed in  

the text-book or by his teacher2 and    
from attention to those with which he is
 already familiar he can be readily led 
to observe and give attention to others 
and to analyze those already in his mind
 by properly directed questions4  ,in   
the field of geology are found the ready
 means for the exercise and development 
of observation and thought4 ,the learner
 begins with ideas which every          
intelligent mind associates with the    
objects described or named1 and by      
degrees the marks of his knowledge are  
increased1 the relations of things are  
grasped1 and the content of his ideas   
associated with the language of his     
science is enlarged4 ,in the process of 
learning the science he has been        
building up his stock of knowledge of   
facts and phenomena1 but1 of more       
importance than that1 he has learned the
 method of observing and of scientific  
thinking4 ,he has had training in the   
methods of reducing the hard facts of   
nature to the laws of thought and       

practice1 he has seen the method by     
which theoretical order is made out of  
the interminable confusion and          
complexity of natural things4  ,beside  
this primary reason for the use of      
geology as a disciplinary science-study1
 there is a second reason arising from  
the symbolic nature of a large group of 
its facts4 ,this aspect of the science  
is best seen in the historical and      
stratigraphical parts of geology1 in    
which fossils are the chief data for    
study4 ,the interpretation of a fossil  
into a species of organism1 having its  
definite place in the elaborate         
classification of the zologist1 or as an
 indicator of the time and place and    
mode of formation of the strata in which
 it is buried1 is1 to be sure1 a most   
intricate and1 at first thought it would
 seem1 an unattractive process4 ,but no 
more so1 ,i would say1 than the         
interpretation of a series of ,greek    
characters4 ,the interpretation of the  
,greek reveals to us the richest results

 of human thought and most perfect laws 
of human speech1 and we find therefore  
in the analysis required the most       
perfect discipline of the powers of     
speech and language4 ,the fossil too    
holds1 ready to be revealed1 the story  
of the history of the world and the laws
 of the evolution of the organic life of
 the globe1 and records an inexhaustible
 wealth of information regarding the    
laws of nature4 ,but as an instrument of
 intellectual discipline its great merit
 lies in its symbolic nature4 ,it is    
this symbolic character of the classical
 languages and of the mathematics which 
fits them to be universal means of      
liberal training4 ,the symbolic nature  
of the fossil fits it to become the     
exponent of training in the pure science
 of nature4 ,the fossil is a mark which 
stands for something1 and thus1 in the  
nature of things1 it asks for           
interpretation4 ,as a symbol it         
stimulates minute and accurate          
observation1 and kindles close and      

exhaustive thought2 as a symbol it      
leaves us the ideas it has engendered   
after it is lost to memory as an        
observation4 ,thus the value of its     
study does not depend upon the retention
 in the memory of the facts brought     
before the mind1 but in the training of 
the mental processes required in its    
interpretation4 ,the study of this      
branch of geology exercises and develops
 all the faculties which are specially  
exercised in any scientific             
investigation4  ,another aspect in which
 it is an ideal means for such training 
comes from the fact that it is equally  
valuable at every stage of progress of  
the student4 ,when first examined it    
means nothing to him4 ,he knows nothing 
of organism1 of strata1 of geological   
time4 ,the fossil gains meaning only as 
he is able to put meaning into it4 ,the 
student must ask questions1 and as step 
by step he answers his questions by more
 minute and wider examination1 the      
fossil holds a fuller interpretation4   

,his studies lead him to investigation  
of the whole field of nature1 the rocks1
 the formation of deposits1 the action  
of the elements1 the conditions of life1
 the forms of organism1 their functions 
and habits1 the laws of growth1 their   
adaptation to environment1 the changes  
of events in time1 the efforts of       
association and struggle for life1 the  
principles of evolution and             
development--the migration and origin   
and extinction of organisms on the      
globe4 ,nothing in nature is without    
interest to him4 ,further than this the 
amount of good he gains is not measured 
by the number of fossils he studies1 but
 by the wideness of his research4 ,a    
handful of fossils from some one        
fossiliferous ledge may be the text for 
a year's study1 and the methods acquired
 in the study may be the nucleus of a   
life's work4 ,in this department of     
geology the possibilities for new       
discoveries1 new developments of science
 are almost endless4 ,as a single author

 thoroughly read develops a wealth of   
knowledge of the laws of language and   
thought1 so geology may be studied by   
the use of a limited set of its         
phenomena and become the introduction to
 the exhaustive study of natural        
science4  ,another advantage attaching  
to geology as a science-study for the   
college curriculum1 arises from the fact
 that it may be pursued deeply without  
the elaborate aid to the senses required
 in other sciences for making minute    
record or measurement of facts or       
phenomena4 ,as in language and          
mathematics1 it is essential to acquire 
a familiarity with the grammar1 the     
dictionary and the symbols1 formulas and
 rules of their usage before the finer  
training in the use of thought begins1  
so the vocabulary and the definitions of
 a science must be acquired before much 
use can be made of the higher discipline
 to be derived from scientific study4   
,in language study this higher training 
comes from practice in making the minute

 analysis1 in detecting the fine shades 
of meaning expressed in the literature  
itself4 ,so it is important in selecting
 a science to be used as a disciplinary 
study that the facts and laws of nature 
with which it is concerned should be    
capable of clear and precise definition1
 and1 moreover1 that it should furnish a
 field for the study of the minute and  
intricate relationship existing between 
the different facts which are to be     
attained by personal inspection of the  
objects themselves4 ,in most of the     
sciences this deeper exercise of        
scientific thought requires for its     
successful pursuit artificial aids to   
the common senses of observation4       
,chemistry must have its purified acids 
and reagents1 test tubes1 and delicate  
scales for measurement of weight and    
volume4 ,mineralogy must have its       
chemical analyses1 or optical           
measurements so fine that microscopes of
 highest power are essential tools for  
the investigation4 ,physics must have   

the most delicate measurements of time  
and space and weight4 ,botany1 for the  
earlier stages of study1 is fully equal 
to geology in these respects1 but its   
scope is much less general4 ,zology     
requires dissections calling for skill  
in manipulation1 and in other respects  
is ill adapted to general classes4 ,but 
precision in the intellectual processes 
of observation and reasoning can be     
cultivated in the use of geological     
facts to their highest and widest       
perfection1 with scarcely any aids to   
the normal faculties of observation4 ,a 
couple of hammers1 a pocket lens1 a     
chisel and a few pointed steel tools for
 revealing fossils1 a tape line1 compass
 and clinometer are the few equipments  
that will enable the geologist to carry 
his investigations to almost any degree 
of thoroughness4  ,what has already been
 said applies to the study of the pure  
science of geology either in the field  
or in the laboratory4 ,there is still   
another use to which this1 as other     

sciences1 may be put in disciplining the
 college student in directions not      
provided for by literary or mathematical
 studies1--the study of man as an       
investigator4 ,in the pursuit of the    
study of geology1 the first instruction 
must be received in didactic form1 but  
after the text-book and lecture stage is
 passed1 or while it is under way       
consultation of the literature of the   
sciences is appropriate4 ,in the use of 
scientific literature the critical      
judgment is brought under training1 and 
the varying interpretations of well     
known phenomena by expert scientists    
suggest the prominent part which the    
notions already in the mind play in the 
interpretation of the external facts    
observed4 ,the experienced geologist    
will recall many cases of honest report 
of impossible facts by men who are      
unable to distinguish between what they 
saw and the false interpretations they  
made of these observations4 ,one man    
will report that a live toad jumped out 

of the middle of a solid piece of coal1 
when it was heated in the stove2 another
 will swear that he saw a fossil shark's
 tooth taken out of a ledge of ,trenton 
limestone4 ,it is evident that our      
memory of observation is not the revival
 of the object producing the sensation1 
but of the idea we framed of the        
sensation at the time4 ,the study of    
original descriptions of objects of     
nature reveals the fact that the        
describer uses the ideas he already has 
in his mind as he does the standard     
foot-rule in his hand for measuring that
 which he describes1 and it is by the   
study of scientific literature and the  
comparison of views of many scientists  
that this highest discipline of the     
observational faculties is attained--the
 power to determine the personal        
equation of error for the observer1 and 
thus see through his descriptions a     
truer representation of the facts than  
the observer himself saw4 ,geological   
literature is admirably adapted for this

 higher discipline1 and in no field of  
science 7,i think not in astronomy      
itself71 has wider and more             
comprehensive thought been applied than 
in geology4 ,while other branches of    
science have been developed and become  
more narrow and special in their        
treatment of the facts concerned1       
geology still stands as the most        
comprehensive of all the sciences of    
nature4                                 
,h4 ,s4 ,williams4    ,yale ,college1   
,november #cj1 #ahib4     ,,the ,,nature
 ,,of ,,the ,,englacial ,,drift ,,of    
,,the ,,mississippi ,,basin4   ,it is of
 some importance1 both to the practical 
work of the field and the theoretical   
deductions of the study1 to determine   
the nature and amount of the drift that 
was carried forward in the body of the  
ancient continental glaciers1 and       
brought out on their terminal slopes and
 at length deposited at their frontal   
edges1 and to distinguish it from that  
which was pushed or dragged or rolled   

along at the bottom of the ice4#aj ,it  
may be helpful to indulge in a          
speculative discussion at the outset to 
prepare the way for the specific        
evidence and the inferences to which it 
leads4  #aj ,debris1 which may be       
imbedded in the basal layer of the ice  
during some part of its transportation1 
but which is brought down to the bottom 
and subjected to basal action in the    
latter part of its course1 and          
ultimately becomes a part of the basal  
deposit1 is not here included in the    
englacial drift4  ,whenever a prominence
 of rock is overridden and enveloped by 
a glacier of the free-moving continental
 type1 one of two things takes place2   
either that part of the ice which passes
 over the summit of the prominence flows
 down its lee slope1 carrying whatever  
debris it dislodges down to the rear    
base1 and thence onward along the bottom
 of the ice1 or else the currents which 
pass on either side of the prominence   
close in behind it before the           

corresponding current which passes over 
the summit reaches the point of their   
junction1 in which case the summit      
current is forced to pass off more      
nearly horizontally into the body of the
 ice1 carrying with it whatsoever debris
 it has dislodged from the summit of the
 prominence and embodied within its     
base4 ,the law of the phenomena appears 
to be that whenever the height of the   
prominence is less than one-half the    
base1 measured transversely to the      
movement of the ice1 the summit current 
will follow down the lee slope2 but     
whenever the height of the prominence is
 more than one-half the transverse base1
 the lateral currents will close in on  
the lee1 and the summit current will    
flow off into the body of the ice4 ,this
 simple law is1 however1 subject to very
 considerable modifications from several
 different sources which may be grouped 
under 7#a7 differences in the friction  
arising from basal contact1 and 7#b7    
differences of internal friction and    

mobility4 ,the lateral currents will    
expose more surface to the sides and    
base of the hill and the adjoining      
plain1 and will be more subject to      
conflicting currents1 while1 on the     
other hand1 being deeper currents1 they 
will presumably be more fluent4 ,these  
and other qualifying conditions will go 
far to vitiate the application of the   
law1 but its statement may have some    
value as representing a general         
conception of the phenomena4 ,when the  
height of the prominence becomes great  
relative to the total thickness of the  
ice1 the fluency of the summit current  
may be much reduced relative to that of 
the central parts of the lateral        
currents4 ,when the prominence reaches  
the surface1 blocks dislodged from it   
are borne away on the surface of the    
glacier1 and constitute superglacial    
drift4 ,blocks dislodged from near the  
summit1 but below the surface of the    
ice1 are presumably carried onward in   
the upper zone of the glacier2 while    

other blocks detached at various but    
sufficient heights on the side of the   
prominence are doubtless borne around   
into the lee and carried forward in the 
same vertical plane as the summit       
stream1 so that there comes to be a     
vertical zone set with boulders moving  
on from the lee side of the nunatak4    
,lofty ledges or plateaus1 with vertical
 or undercut faces1 furnish similar     
means for the lodgment of debris within 
the body of the ice4  ,in these and     
doubtless in other ways it appears that 
there came to be lodged directly within 
the body of the ,pleistocene glaciers at
 some considerable distances above their
 bases1 blocks derived from rock        
prominences that rose with sufficient   
steepness above the general surface of  
the country over which the ice passed4  
,the lodgment of debris on the lateral  
borders of glaciers is neglected here   
because it has little or no             
applicability to the phenomena of the   
upper ,mississippi basin4 ,it is also   

doubtful whether any prominences        
protruded through the ice except near   
the thin edge1 when advancing and       
retreating1 and these are too           
inconsiderable to merit attention4  ,it 
is obvious1 upon consideration1 that    
blocks detached from summits or from the
 sharp angles of out-jutting ledges or  
plateaus might suffer some glacial      
abrasion in the process of their        
dislodgment and transposition along the 
crest or projecting angle1 but that in  
general such abrasion would be small1   
and1 in most cases1 nearly or quite     
absent4 ,the debris so incorporated in  
the body of the ice would be1 for the   
most part1 angular1 and1 as it was      
brought forward in the ice1 it would    
probably suffer very little abrasion4   
,if it continued to move forward in the 
plane in which it started1 descending   
only so much as the bottom wastage of   
the ice required1 it would be brought   
out to the terminal slope of the ice    
sheet by virtue of the melting away of  

the ice above1 and thence it would be   
carried on down the terminal slope as   
superglacial debris1 and dropped at the 
frontal edge4 ,if this be the true and  
full history1 there would be no         
commingling of this englacial matter    
with the subglacial debris4 ,it is      
evident1 that the englacial matter      
brought forward from the crest of one   
prominence would be intermingled with   
that brought forward from other         
prominences lying in a line with it1 or 
lying so near it that the lateral       
spreading of the debris would lead to   
commingling4 ,it is also clear that     
variations in the direction of currents 
would tend to the same result1 so that  
englacial matter from different         
prominences of the same general region  
might be commingled4 ,so also englacial 
material1 by crevassing and by the      
descent of streams from the surface to  
the base1 would be carried down to the  
bottom and mingled with the subglacial  
debris4 ,so also blocks broken away from

 the base of the prominence which       
yielded the englacial erratics might be 
moved forward along the bottom parallel 
with the englacial material above1 and  
lodged at any point along the line4 ,it 
is therefore to be expected that the    
basal deposits will contain the same    
rock species as the englacial1 but if   
there be no process by which the basal  
material is carried upward the reverse  
will not be the case1 and there will be 
a clear distinction between the         
englacial deposit and the subglacial    
deposit1 in composition as well as      
physical state4  ,not a few glacialists1
 however1 advocate in somewhat differing
 forms and phases the doctrine that     
basal material is carried upward into   
the body of the glacier and at length   
reaches the surface1 and that at the    
extremity of the ice this is commingled 
with any erratics that may be englacial 
or superglacial by original derivation4 
,this doctrine appears to have had its  
origin in the endeavor to explain the   

very common fact that glacial drift has 
been carried from lower to higher       
altitudes4 ,erratics are often found    
lodged several hundred feet higher than 
the outcrop from which they were        
derived4 ,it has never seemed to me1    
however1 that this phenomenon           
necessarily was different in kind from  
that which takes place in the bottom of 
every stream2 at least ,i have not come 
in contact with any instances that      
seemed to require a different           
explanation1 except those connected with
 kames and eskers that require a special
 explanation in any case4 ,we are so    
accustomed to view streams from above1  
and so accustomed to study the extinct  
glaciers from the bottom1 that we are   
liable to overlook the community of some
 of the simpler processes involved alike
 in both phenomena4 ,the dictum that    
water never runs up hill is measurably  
true of the surface currents of the ice 
as well as water1 but it altogether     
fails when applied to the basal currents

 of either4 ,it is probable that there  
is no natural stream of any length in   
which1 at some part of its course1 basal
 debris is not carried from lower to    
higher altitudes and lodged there4 ,if  
the bed of any stream were made dry and 
the debris in it critically examined1 it
 would be found that at numerous points 
the silts or sands or gravels had been  
carried from the bottom of some basin in
 its bed to the higher rim or bar or    
reef that bordered it on the downstream 
side4 ,so ,i conceive that1 on a grander
 scale1 the natural result of the flow  
of the basal ice of a continental       
glacier over the inequalities of the    
country was the lifting of material from
 some of the lower horizons and its     
lodgment on the crests of ridges or the 
slopes or summits of mountains that lay 
athwart its course4  ,so again1 it is   
certain that a considerable part of the 
peripheral drainage of glaciers takes   
place through tunnels beneath the ice4  
,it is reasonable to suppose that during

 the winter season1 when the drainage is
 slack1 these tunnels tend to collapse  
in greater or less degree1 under the    
continued pressure of the ice and the   
fattening of the glacier1 so that in the
 early part of the next melting season  
the contracted tunnels may be           
over-flooded by glacial waters4 ,to the 
extent that these tunnels become        
incompetent the water would become      
ponded back in the crevasses and moulins
 by which the surface-water gains access
 to them4 ,they thus come to have       
something of the force of water flowing 
in tubes1 and may be presumed to be     
capable of forcing rounded material to  
some considerable height1 and of        
carrying ice-imbedded boulders to any   
point reached by the stream4 ,these     
tunnels probably undulate with the      
bottom1 and lodgment along them takes   
place wherever enlargement permits4     
,without1 therefore1 appealing to any   
upward cross currents within the ice    
itself1 it is possible to explain the   

transportation of the drift from lower  
to higher altitudes4 ,i have never seen 
phenomena of this kind that seemed to   
call for any other explanation than     
these4 ,i am not prepared to say that   
there are no such phenomena4 ,one of the
 purposes of this article will have been
 accomplished1 if it shall call forth a 
critical statement of phenomena that    
require the assumption of internal      
upward movements of the ice to account  
for them1 and of the criteria which     
distinguish such phenomena from those   
that may be referred to upward basal    
movements such as are common to all     
streams or to the exceptionally         
conditioned subglacial streams4 ,that   
there are upward internal movements in  
most streams is as much beyond question 
as the existence of upward basal        
currents in rivers and glaciers1 but    
they are dependent chiefly upon the     
velocity of the current and the         
irregularity of the bottom4             
,theoretically1 as ,i understand1 a     

stream moving in a straight course on a 
perfectly smooth bottom would not       
develop an upward cross current4 ,each  
lower layer would move slower than that 
above it by reason of basal friction1   
but they would move on in parallel      
lines4 ,but if irregularity of bottom be
 introduced the parallelism is obviously
 destroyed1 and if the velocity be high 
so that the momentum of the particles   
becomes great relative to their         
cohesion1 irregular internal movements  
will result1 and these will often be of 
a rotary nature in vertical planes      
bringing the basal parts of the fluid to
 the surface or the reverse4 ,for this  
reason rapid streams abound in rotary   
currents1 while slow streams do not4    
,now it is quite obvious that a stream  
of water moving at a rate of three or   
four feet per day1 or even fifty or     
sixty feet per day1 would not develop   
perceptible upward currents1 and        
certainly would not lift the lightest   
silt from its bottom4 ,i do not think   

there are any theoretical grounds for   
believing that internal glacial currents
 are developed1 which flow from base to 
surface1 carrying bottom debris to the  
top4  ,one of the most remarkable       
expressions of the drift phenomena of   
the ,upper ,mississippi region consists 
of belts of boulders stretching for     
great distances over the face of the    
country1 and disposing themselves in    
great loops after the fashion of the    
terminal moraines of the region with    
which they are intimately connected4    
,besides this1 there are numerous       
patches of boulders of more or less     
irregular form and uncertain relations4 
,the whole of these have not been       
studied in detail1 but a sufficient     
portion of them have received careful   
examination to justify the drawing of   
certain conclusions from them4 ,those   
which have been most studied lie in     
,ohio1 ,indiana1 ,illinois1 ,michigan1  
,wisconsin1 ,iowa and ,dakota4 ,those of
 the first three ,states have been most 

carefully traced and their constitution 
is such as to give them the greatest    
discriminative value4 ,to these our     
discussion will be limited chiefly4#aa  
#aa ,parts of these tracts were long    
since described by ,bradley of the      
,illinois ,survey4 7,geol4 ,surv4 ,ill41
 ,vol4 ,,iv4 p4 #bbg74 ,collet of the   
,indiana ,survey 7,an4 ,rep4 #ahge1 p4  
#djd7 and ,orton and ,hussey of the     
,ohio ,survey 7,geol4 ,surv4 ,ohio1     
,vol4 ,,iii41 pp4 #dab1 #dad and #dge74 
,the relationship of these tracts to    
morainic lines and to each other ,i     
worked out some years since 7,third ,an4
 ,rep4 ,u4 ,s4 ,g4 ,s4 pp4 #cca1 #ccb1  
#ccd7 but ,i owe many details and some  
important additions to my associate1    
,mr4 ,leverett4  ,emerging from the     
dunes at a point north of the ,iroquois 
river in ,jasper county1 northwestern   
,indiana1 a well characterized belt of  
surface boulders stretches westward to  
the ,state line1 just beyond which it   
curves about to the south and then to   

the east1 and re-enters ,indiana a      
little south of the northwest corner of 
,benton county4 ,it soon turns abruptly 
to the south and reaches the ,wabash    
river near the centre of ,warren county4
 ,the immediate valley of the ,wabash is
 thickly strewn with boulders from the  
point where the belt reaches it to the  
vicinity of ,west ,point on the western 
line of ,tippecanoe county4 ,the        
uplands1 however1 do not give any clear 
indication of the continuity of the     
belt1 and the connection is not         
altogether certain4 ,there is an inner  
well-marked belt that branches away from
 this in the central part of ,benton    
county and runs southeasterly into the  
northwestern quarter of ,tippecanoe     
county1 beyond which only scattered     
boulders occur1 which leaves its precise
 connections also in doubt4 ,but        
starting from ,west ,point1 which is    
less than a dozen miles from the point  
where the two belts cease to be         
traceable with certainty1 a well-defined

 belt1 one or two miles wide1 runs      
southeasterly across the southwestern   
corner of ,tippecanoe county and the    
northeastern quarter of ,montgomery     
county to the vicinity of ,darlington1  
beyond which its connection is again    
obscure1 although boulders occur        
frequently between this point and the   
northwestern corner of ,brown county1   
where boulders are very abundant4 ,so   
also1 patches of exceptionally abundant 
boulders occur in the west central part 
of ,clinton county4 ,these may be       
entitled to be regarded as a connecting 
link between the train which enters     
northwestern ,tippecanoe county and that
 of northwestern ,boone county1 as      
scattered boulders of the surface type1 
but of not very exceptionally frequent  
occurrence1 lie between them4 ,however  
this may be1 a belt of much more than   
usually frequent surface boulders       
stretches southeasterly to the vicinity 
of ,indianapolis1 and probably connects 
with a very well-marked belt lying near 

the south line of the southeast quarter 
of ,marion county and in the            
northeastern part of ,johnson county4   
,there is also a well-defined tract in  
southeastern ,hendricks county1 running 
east and west1 without evident          
connection with the foregoing tracts1   
though it may be the equivalent of the  
,darlington belt4 ,there is also a      
somewhat unusual aggregation in the form
 of irregular belts in southeastern     
,johnson county1 in the vicinity of     
,nineveh1 and in southern ,shelby       
county4 ,the belt south of ,indianapolis
 is probably to be correlated by        
scattered boulders only slightly more   
abundant than those of the adjacent     
region1 but of the surface type1        
stretching northeasterly to near the    
center of the west half of ,henry       
county1 where a well-marked belt again  
sets in4 ,from this point the tract runs
 northeasterly nearly to the north limit
 of the county1 where it turns easterly 
and runs in the vicinity of the line    

between ,randolph and ,wayne counties to
 near the ,ohio line1 where it curves to
 the southeast entering ,ohio near the  
northwest corner of ,preble county4 ,in 
its southeasterly course across that    
county it is phenomenally developed as  
has been well shown by the descriptions 
of ,professor ,orton4 ,soon after       
entering ,montgomery county it curves   
about to a northeasterly course1 and    
crossing the great ,miami river1 a few  
miles above ,dayton1 holds its northeast
 course across the southeastern part of 
,miami county1 the northwestern part of 
,champaign county1 and thence on to     
about the center of ,logan county1 where
 it curves about and runs in a direction
 a little east of south to near the     
southeast corner of ,champaign county1  
beyond which it ceases to be a specially
 notable phenomenon4  ,in the region    
between the ,wabash and ,kankakee       
rivers1 in northern ,indiana1 there are 
numerous tracts of irregular form over  
which surface boulders in phenomenal    

abundance are scattered4 ,these are     
particularly noticeable in southern     
,jasper county2 in the vicinity of      
,wolcott1 ,monon and ,chalmers in ,white
 county2 near ,star ,city in ,pulaski   
county2 in the southeastern corner of   
,stark county1 and very generally along 
the great interlobate moraines1 lying   
parallel with the ,eel river1 and some  
others of the ,saginaw glacial lobe4    
,these are so associated with the       
inter-tangled morainic phenomena of that
 region as not to admit of convenient   
and brief description in their genetic  
relationships4  ,the well-defined tracts
 have a most significant distribution4  
,the first part described is associated 
with the terminal moraine that marked   
the margin of a lobe of ice that moved  
westward along the axis of the ,iroquois
 basin to a point a few miles beyond the
 ,indiana-,illinois line4 ,the portion  
that runs southward to the ,wabash is   
associated with the moraine that follows
 the same course1 and runs at right     

angles over the older moraines of the   
,lake ,michigan lobe4 ,the tract in     
,tippecanoe and ,montgomery counties1   
that in south ,marion county1 and that  
in ,henry and ,randolph counties1 in the
 eastern part of the state1 are         
associated with the terminal moraines   
that form a broad loop with the ,west   
,white river basin lying in its axis4   
,in western ,ohio the belt is intimately
 associated with a moraine that bordered
 the ,miami lobe of the ice sheet1 and  
the south-trending portion in eastern   
,logan and ,champaign counties lies on  
the western margin of the ,scioto lobe4 
,the relationship of these tracts to    
terminal moraines is very clear and     
specific4 ,they constitute marginal     
phenomena of the ancient ice sheet4     
,their distribution completely excludes 
their reference to floating ice1 for    
they not only undulate over the surface 
utterly negligent of any horizontal     
distribution1 but they are disposed in  
loops in crossing the basins of the     

region1 and the convexities of these    
loops are turned down stream4 ,these    
basins for the most part open out in    
southerly or westerly directions which  
makes it improbable that ice-bearing    
bodies of water occupied them4 ,but if  
this were not fatal1 certainly the fact 
that the convexities of the boulder     
belts are turned down stream and cross  
the centers of the basins is precisely  
contrary to the distribution they must  
have assumed if they were due to        
floating ice in bodies of water         
occupying the basins4 ,i hold it1       
therefore1 to be beyond rational        
question that these tracts were         
deposited as we find them by the margins
 of the glacial lobes that invaded the  
region4  ,if these boulder belts were of
 the same nature as the average boulders
 of the till-sheets beneath them1 then  
the simple fact of unusual aggregation  
might be plausibly referred to the      
accidents of gathering and deposition4  
,but they are very clearly distinguished

 from the average boulders of the till  
by several characteristics4  #a4 ,they  
are superficial4 ,sometimes they rest   
completely on the surface1 sometimes    
they are very slightly imbedded1        
sometimes half buried1 sometimes they   
protrude but a slight portion1 and      
sometimes they are entirely concealed1  
but lie immediately at the surface4 ,in 
all cases the aggregation is distinctly 
superficial4 ,where they are buried1 the
 burying material is usually of         
different texture and composition from  
the subjacent till1 and appears to be   
distinct in origin from it4 ,the        
superficiality of the tract is very     
obvious almost everywhere1 and is       
especially so in regions where the      
subjacent till is of the pebble-clay    
rather than boulder-clay order1 for the 
comparative absence of boulders below   
emphasizes the contrast4 ,throughout    
most of the region the subjacent till is
 not of a very bouldery type1 so that   
the distinction is generally a marked   

one4  #b4 ,the boulders of the belts are
 almost without exception derivatives   
from the crystalline terranes of        
,canada4 ,those of the great tract      
especially under consideration were     
derived from the typical ,huronian rocks
 of the region north of ,lake ,huron1   
and from granitic and gneissoid rocks   
referable to the ,laurentian series of  
the same region4 ,these last1 however1  
cannot be sharply distinguished from the
 granitic rocks derived from other parts
 of the ,laurentian terrane4 ,the       
,huronian rocks are very easily         
identified because of the peculiarities 
of some of the species4 ,among these the
 one most conspicuously characterized is
 a quartz-and-jasper conglomerate4 ,the 
matrix is usually a whitish quartzite4  
,this is studded with pebbles of typical
 red jasper and of duller rocks of      
jasperoid nature1 which grade thence    
into typical quartzite pebbles4 ,with   
these are mingled crystalline pebbles of
 other varieties4 ,another peculiar     

erratic comes from the slate            
conglomerate of ,logan4 ,it consists of 
a slaty matrix through which are        
scattered rather distantly pebbles of   
granitic1 quartzitic and other          
crystalline rocks4 ,this is one of the  
forms of the basal conglomerate of      
,irving4 ,other varieties of this basal 
conglomerate are present4 ,in addition  
to these very peculiar rocks1 a         
quartzite of a very light greenish      
semi-translucent hue has a wide         
distribution along the tract4 ,it is    
readily distinguishable from the        
numerous other quartzites of the drift  
of the interior4 ,some years since1 on  
returning from my first field           
examination of a portion of this belt1  
,i sent a typical series of chips from  
the characteristic erratics to          
,professor ,irving1 who had recently    
returned from the study of the original 
,huronian region4 ,he returned a suite  
of chippings that matched them perfectly
 throughout1 all of which were taken in 

situ in the region north of ,lake       
,huron4  ,among the boulders of the belt
 are occasionally found specimens of    
impure limestone or of limy sandstone   
that might perhaps be referred          
doubtfully to some member of the        
paleozoic series2 but on the other hand1
 might with equal or greater probability
 perhaps be referred to the similar     
rocks of the ,huronian series4 ,these   
are quite rare1 never forming1 so far as
 my observations go1 as much as one per 
cent4 of the series4 ,in the several    
definite enumerations made to determine 
the percentage of the doubtful          
specimens1 the result never exceeded a  
fraction of one per cent4 ,in the most  
extensive enumeration the result was    
about one-half of one per cent4 ,aside  
from these doubtful specimens there are 
practically no boulders in the belts    
that can be referred to any of the      
paleozoic rocks that intervene in the   
#ejj miles between the parent series    
north of ,lake ,huron and the tract over

 which the boulders are now strewn4     
,occasionally there may be seen erratics
 from the paleozoic series at or near   
the surface1 but they are not usually so
 disposed on the surface as to appear to
 be true members of the superficial     
boulder tract4 ,there is1 therefore1 the
 amplest ground for the assertion that  
these boulder tracts are of distant     
derivation1 and that they are           
essentially uncommingled with           
derivatives from the intermediate       
region4  #c4 ,the boulders of this      
series are much more angular than those 
of the typical till sheets4 ,some of    
them1 indeed1 are rounded1 but the      
rounding is generally of the type which 
boulders derived by surface degradation 
and exfoliation present4 ,they rarely   
have the forms that are distinctively   
glacial4 ,quite a large percentage are  
notably angular1 and have neither       
suffered glacial rounding nor spherical 
exfoliation4 ,some few are glacially    
worn and scratched1 but the percentage  

of these is small4  ,the tracts         
therefore present these four salient    
characteristics3 7#a7 the boulders are  
derived from distant crystalline        
terranes 7#djj to #ejj miles7 and are   
essentially uncommingled with rock from 
the intervening paleozoic terranes2 7#b7
 they are essentially superficial1 and  
the associated earthy material has a    
texture differing from that of the      
subglacial tills2 7#c7 they are notably 
angular and free from glacial abrasion1 
except in minor degree2 7#d7 the tracts 
are so associated with terminal moraines
 and so related to the topography of the
 region1 that there is no rational      
ground for doubt that the boulders were 
borne to their present places by the    
glaciers that produced the correlative  
moraines4  ,in contrast to these        
superficial boulder formations1 the till
 sheets below are made up of a very     
large percentage of glacial clay whose  
constitution shows that it was produced 
in part by the grinding down of the     

paleozoic series4 ,in this are imbedded 
boulders and pebbles that were derived  
from the paleozoic series as indicated  
by their petrological character1 and1 in
 many instances1 demonstrated by        
contained fossils4 ,while a small part  
of the boulders contained in the till   
are angular or but slightly worn1 the   
larger part are blunted1 bruised1       
scratched and polished by typical       
glacial action4 ,this obvious grinding  
of the boulders1 taken in connection    
with the clay product resulting from the
 grinding1 affords a clear demonstration
 that the deposit was produced at the   
base of the ice by its pushing1         
dragging1 rolling action4  ,the two     
formations1 therefore1 stand in sharp   
contrast2 the one indicating the passive
 transporting action of the ice in      
bearing from their distant homes north  
of the lakes the crystalline boulders   
and dropping them quietly on the        
surface1 the other indicating the active
 dynamic function of the ice in rubbing1

 bruising and scoring the material at   
its base4 ,the one seems to me a clear  
instance of englacial and superglacial  
transportation2 the other an equally    
clear example of subglacial push1 drag  
and kneading4  ,now if it were the habit
 of an ice-sheet of this kind to carry  
material from its bottom to the surface 
by internal movement1 it would seem that
 the distance of #djj to #ejj miles     
which intervened between the source of  
the crystallines and the place of their 
deposit would have furnished ample      
opportunity for its exercise1 and that  
there would have been commingled with   
the englacial and superglacial material 
many derivatives from the intermediate  
region1 and these derivatives should    
have borne the characteristic markings  
received by them while at the base of   
the ice4 ,the very conspicuous absence  
of such commingling1 and the absence or 
phenomenal rarity of anything that even 
looks like such a commingling1 appears  
to me to testify in quite unmistakable  

terms to the distinctness of the methods
 of transportation4 ,in view of the     
great territory over which this         
particular belt is spread1 and the      
greater territory which is embraced in  
the other tracts not here specially     
considered1 there is left little ground 
for doubt that this distinctness of     
englacial from basal transportation was 
a prevailing fact and not an exceptional
 one4 ,this is supported by concurrent  
evidence derived from the territory west
 of ,lake ,michigan4 ,this territory    
unfortunately does not bear erratics    
that have equally distinct              
characteristics1 but1 so far as my      
observation goes1 the phenomena are     
alike throughout4 ,i am therefore       
brought to the conclusion that1 in the  
interior at least1 there was no habitual
 lifting of boulders from the base of   
the ice sheets to the surface1 nor any  
habitual commingling of basal with      
englacial and superglacial material1    
except1 of course1 as it took place by  

virtue of the falling of the latter     
through crevasses to the base1 and by   
mechanical intermixture of the two at   
the edge of the ice4  ,the amount of    
englacial till under this view is little
 more than that which was lodged in the 
body of the ice in its passage over the 
knobs and ridges of the hilly and       
semi-mountainous regions of the north4  
,to this is perhaps to be added         
occasional derivatives from the more    
abrupt prominences of the paleozoic     
region and the superficial dust blown   
upon the ice from the surrounding land1 
which was probably the chief source of  
the silty material intermingled with the
 superficial boulders4 ,the total amount
 is thus quite small1 though important  
in its significance4  ,the eskers and   
kames of the region are made up of      
derivatives from the basal material as  
shown by 7#a7 the local origin of the   
material in large part1 7#b7 the        
mechanical origin of the sands and      
silts1 7#c7 the not infrequent glacial  

markings of the pebbles and boulders1   
and 7#d7 the disturbed stratification of
 the beds4#ab ,if ,i am correct in      
respect to the kind and amount of the   
englacial and superglacial material1 it 
is obvious that eskers and kames1 such  
as are found in the interior1 could not 
be derived from englacial or            
superglacial sources4 ,the term         
englacial as here used does not include 
such materials as may be lodged in the  
basal stratum of the ice and brought    
down to the actual bottom by basal      
melting4  #ab ,see ,hillocks of ,angular
 ,gravel and ,disturbed ,stratification1
 ,am4 ,jour4 ,sci4 ,vol4 ,,xxvii41 ,may 
#ahhd1 pp4 #cgh-cij4  ,the conclusions  
drawn from the phenomena of the plains  
of the interior are not necessarily     
applicable to more hilly or mountainous 
regions4                                
,t4 ,c4 ,chamberlin4     ,studies for   
,students4   ,,distinct ,,glacial       
,,epochs1 ,,and ,,the ,,criteria ,,for  
,,their ,,recognition4#ac  #ac ,read    

before the ,american ,geological        
,society at ,ottawa1 ,dec41 #ahib4   ,i4
 ,introduction4  ,it has long been      
evident that writers on glacial geology 
are not at one concerning some of the   
important questions which underlie the  
interpretation of the history of the    
glacial period4 ,certain recent         
publications have served to emphasize   
the differences between them4 ,there are
 two questions1 at least1 concerning    
which there must be agreement1 or at any
 rate a common understanding1 before    
existing differences can be eliminated  
or justly evaluated4 ,when the answers  
to these questions have been agreed     
upon1 or when the positions of the      
contending parties are clearly          
understood1 it may be found that some of
 the apparent antagonisms have no better
 basis than differences in definition4  
,stated interrogatively1 the two        
questions referred to are these3 #a4    
,what constitutes a glacial epoch as    
distinct from other glacial epochs8 and 

#b4 ,what are the criteria for the      
recognition of distinct glacial epochs1 
if such there were8   ,,ii4 ,the ,idea  
of a ,glacial ,epoch4  ,it is           
conceivable that1 after the development 
and extension of a continental          
ice-sheet1 it might be wholly wasted    
away4 ,the maximum extension of such an 
ice-sheet would mark the culmination of 
a glacial epoch4 ,if subsequently       
another ice-sheet of considerable       
dimensions were accumulated1 its        
development and extension would         
constitute a second glacial epoch4      
,these successive ice-sheets might be so
 related to each other in time1 in      
position1 and in the sequence of        
geological events1 as to be regarded as 
separate epochs of the same glacial     
period4#ad ,on the other hand they might
 be so widely separated from each other 
in time1 in position1 and in the        
sequence of geological events1 as to    
make their reference to separate glacial
 periods more appropriate4 ,in any case 

their separation would be sufficiently  
marked to necessitate their reference to
 separate ice epochs4 ,so far we believe
 there would be no disagreement4  #ad   
,the terms period and epoch are here    
used in the sense in which they have    
been used most commonly in the          
literature of glacial geology in the    
,united ,states4  ,if1 instead of       
entirely disappearing1 the first        
ice-sheet suffered great reduction of   
volume and area1 and if this reduction  
were followed by a second great         
expansion of the ice1 might the time of 
such expansion be regarded as a second  
glacial epoch of the common glacial     
period8 ,to this question1 too1 as thus 
stated1 we apprehend there would be but 
one answer1 and that affirmative4  ,it  
seems certain that the edge of the      
continental ice-sheet was subject to    
more or less extensive oscillations1 as 
are the ends of glaciers and the edges  
of ice-sheets to-day4 ,how much of an   
oscillation is necessary1 and under what

 attendant conditions must it take      
place1 in order that the recession of   
the ice-edge shall mark an interglacial 
and its re-advance a distinct glacial   
epoch8 ,when the question takes this    
specific form1 and when inquiry is made 
concerning the quantitative value of the
 different elements entering into the   
problem1 we reach the battled ground4   
,it is the battled ground1 partly       
because it is the ground of             
misunderstanding4 ,it is the ground of  
misunderstanding1 partly because        
glacialists are not agreed as to the    
meaning of certain terms in common use  
by them4  ,four elements seem to enter  
into the idea of an ice epoch as        
distinct from other ice epochs4 ,these  
are 7#a7 the distance to which the ice  
retreated between successive advances2  
7#b7 the duration of the retreat1 or the
 time which elapsed between successive  
ice extensions2 7#c7 the temperature of 
the region freed from ice during the    
time between maxima of advance2 and 7#d7

 the intervention between successive    
advances1 of changes interrupting the   
continuity of geological processes4     
7#a47 ,it would be arbitrary to name any
 definite distance to which the ice must
 recede in order to constitute its      
re-advance a distinct ice epoch4 ,it    
would be not so much a question of miles
 as a question of proportions4          
,considering this point alone1 we       
presume it would be agreed that an      
ice-sheet should have suffered the loss 
of a very considerable proportion of its
 mass1 and that it should have dwindled 
to proportions very much less than those
 subsequently attained1 before its      
re-advance could properly be called a   
separate glacial epoch4 ,to be specific1
 if the ,north ,american ice-sheet1     
after its maximum extension1 retreated  
so far as to free the whole of the      
,united ,states from ice1 we should be  
inclined to regard a re-advance as      
marking a distinct ice epoch of the same
 glacial period1 if in such re-advance  

the ice reached an extension comparable 
with that of the earlier ice-sheet4     
,especially should we be inclined to    
refer the second ice advance to a second
 glacial epoch1 if it1 as well as the   
preceding retreat1 were accompanied by  
favoring phases of some or all the other
 three elements entering into the notion
 of a glacial epoch4 ,in this statement 
we do not overlook the fact that a      
northerly region--as ,labrador or       
,greenland--might be continuously       
covered with ice throughout the time of 
the two glaciations of the more         
southerly regions4 ,but this is not     
regarded as a sufficient reason for     
discarding the notion of duality4       
,greenland has very likely been         
experiencing continuous glaciation since
 a time antedating that of our first    
glacial deposits4 ,the renewal to-day of
 glaciation comparable in extent to that
 of the glacial period would certainly  
be regarded as a distinct glacial epoch1
 if not a distinct glacial period1 even 

though ,greenland's glaciation may not  
have been interrupted4 ,scandinavia and 
,switzerland have probably not been     
freed from ice since the glacial period4
 ,their snow and ice fields are probably
 the direct descendants of the ice      
fields of the glacial period4 ,an       
expansion of the existing bodies of ice 
in these countries to their former      
dimensions1 would constitute a new      
glacial epoch1 if not a new glacial     
period4 ,analogous subdivisions in      
pre-,pleistocene formations have been   
frequently recognized4  7#b7 ,the       
application of the time element is      
hardly susceptible of quantitative      
statement4 ,we are inclined to think    
that it would be generally agreed that1 
with a given amount of recession of the 
ice1 its re-advance would be more       
properly regarded as a distinct glacial 
epoch if the interval which had elapsed 
since the first advance were long4      
,whether a longer time between the      
separate advances might reduce the      

amount of recession necessary in order  
to constitute the second advance a      
second epoch1 we are not prepared to    
assert2 but we are inclined to think it 
might4  7#c7 ,the third element is      
perhaps somewhat more tangible than the 
second4 ,if1 during the retreat of the  
ice1 the climate of a region which was  
twice glaciated became as temperate as  
that of the present day in the same     
locality1 we should be inclined to      
regard the preceding and succeeding     
glaciations as distinct ice epochs1     
especially if the intervening recession 
were great and its duration long4       
,unfortunately for simplicity and ease  
of determination1 there are difficulties
 in determining with precision how far  
the ice retreated between successive    
maxima of advance1 how long the interval
 during which it remained in retreat1   
and the extent to which the climate was 
ameliorated1 as compared with that which
 went before and that which followed4   
7#d7 ,if changes of any sort which      

interrupt the continuity of geological  
processes intervened between successive 
maxima of advance of the ice1 the       
separation of the later advance from the
 earlier1 as a distinct ice epoch1 would
 be favored4 ,how great the intervening 
changes should be in order to constitute
 the re-advance a distinct ice epoch1 is
 a point concerning which there might be
 difference of opinion4 ,but it is      
altogether possible that such changes   
might intervene as alone to give        
sufficient basis for the separation4    
,orographic movements1 resulting either 
in continental changes of altitude or   
attitude are among the events which     
might come in to separate one ice epoch 
from another4 ,changes of this sort have
 often furnished the basis for the major
 and minor divisions of time in other   
parts of geological history1 so that    
there can be no question as to their    
adequacy1 if they were of sufficient    
magnitude4 ,we hold that the            
intervention of orographic or other     

important geologic changes might reduce 
to a minimum the amount of recession1   
the duration of the recession1 and the  
warmth of the intervening climate       
necessary to constitute the separate ice
 advances separate ice epochs4 ,the     
absence of great orographic or other    
changes in glaciated regions between    
successive advances of the ice would be 
no proof that such advances should not  
be regarded as separate epochs4         
,divisions of equal importance have     
often been made without evidence of such
 changes4  ,from the foregoing          
discussion1 brief as it is1 it will be  
seen that within certain narrow limits  
the definition of a glacial epoch1 as   
distinct from other glacial epochs1 must
 be more or less arbitrary4 ,it is less 
important that an arbitrary definition  
should be accepted1 than that the same  
meaning should be attached to technical 
terms in common use among geologists4   
,in the interest of harmony and of a    
common understanding1 and without the   

violation of any truth of science1 we   
believe it would be well if the         
conception of a glacial epoch1 as framed
 by those who are our leaders in        
position and in fact1 were made the     
basis for our usage of the term4        
,,iii4 ,the ,criteria of ,distinct      
,glacial ,epochs4  ,if there have been  
differences of opinion concerning the   
nature of ice epochs1 as distinct from  
each other and from ice periods1 there  
has been a failure to adequately        
apprehend the nature1 the extent1 and   
the meaning of the real criteria on     
which the final recognition of separate 
ice epochs1 if such there were1 must be 
based4  ,such criteria are several in   
number4 ,they are of unequal value4 ,in 
some instances a single one of them     
might be quite sufficient to establish  
the fact of two ice epochs4 ,in other   
cases1 single criteria which might not  
be in themselves demonstrative1 have    
great corroborative weight1 when found  
in association with others4 ,in all     

cases1 much discretion must be used in  
the interpretation of these criteria4   
,they may be enumerated under several   
specific heads4  7#a7 ,forest ,beds4    
,beds of vegetal deposits or old soils  
are frequently found between layers of  
glacial drift4 ,this is one of the      
criteria most commonly cited1 because it
 is of common occurrence and easy of    
recognition4 ,the advocates of the unity
 of the glacial period maintain that    
such beds of organic matter might become
 interbedded with morainic debris during
 minor oscillations of the ice's edge4  
,the phenomena of existing glaciers make
 it evident that forest beds or soils   
might be enclosed by the deposits of an 
oscillating ice edge4 ,by repeated      
oscillations of the ice's edge during   
the general retreat of the ice1 such    
vegetal beds might become               
interstratified with glacial drift more 
or less frequently over all the area    
once covered by the ice1 and from which 
it has now disappeared4 ,the mere       

presence of vegetable material between  
beds of drift is therefore no proof of  
distinct ice epochs4 ,this does not     
destroy the value of the vegetal beds as
 a criterion for the recognition of     
distinct ice epochs1 but it makes       
caution necessary in its application4   
,it does not follow that1 since some    
inter-drift forest-beds do not prove    
interglacial epochs1 none do4 ,the      
question is not how forest-beds might   
originate1 but how existing forest-beds 
did originate4  ,where the plant-remains
 found in the relations indicated are so
 well preserved as to make              
identification of the species possible1 
we have a means of determining1 with    
some degree of accuracy1 the climatic   
conditions which must have obtained at  
the place where the plants grew during  
the time of their life4 ,if these       
interbedded plant-remains are of such a 
character as to indicate a temperate    
climate1 we can not suppose that they   
grew at the immediate edge of the ice1  

and therefore that they were buried     
beneath its oscillating margin4 ,to be  
specific1 if the inter-drift plant      
remains in any given locality of the    
area once covered by ice are such as to 
indicate a climate as warm as the       
present in the same locality1 the ice   
must have receded so far to the         
northward that its re-advance might1 in 
our judgment1 appropriately be regarded 
as a separate ice epoch4  ,it has been  
suggested in opposition that temperate  
conditions may obtain even up to the    
edge of the ice1 and that interbedded   
vegetal remains indicating temperate    
climate do not prove any considerable   
recession of the ice4 ,the phenomena    
about existing glaciers have been       
appealed to in support of this demurrer4
 ,but the objection is not well taken4  
,the climatic conditions which obtain   
about the borders of small1 local       
glaciers1 are not a safe guide as to    
climatic conditions which obtained about
 the margin of a continental ice-sheet1 

any more than the climatic conditions   
which obtain about a small inland lake  
are a safe criterion as to the climatic 
conditions about a sea-coast4 ,the      
general principles of climatology1 as   
well as specific facts concerning plant 
distribution1 seem to us to indicate    
that the climate about the border of a  
continental ice-sheet must have been    
arctic4  ,it is evident that the greater
 the distance north of the overlying    
drift remains of temperate plants are   
found1 the more conclusive becomes the  
evidence4 ,plant remains indicating     
temperate climate at the very margin of 
the drift sheet which overlies them1    
would be less conclusive than similar   
evidences one hundred miles to the      
northward4 ,it might be difficult to    
prove in any given instance that the ice
 which deposited the drift overlying    
plant remains advanced one hundred      
miles1 or any other specific distance1  
south of any particular underlying      
forest bed4 ,if the forest bed were     

continuous for the whole distance1 the  
case would be clear4 ,it would also be  
conclusive if the continuity of the     
drift overlying a forest bed at any     
point with that of a remote point to the
 south1 could be demonstrated4 ,in spite
 of these difficulties in its           
application1 the vegetal beds constitute
 a valuable criterion in making the     
discriminations under consideration1    
when they are properly applied4 ,under  
proper circumstances the criterion may  
be conclusive when taken alone1 and it  
may have corroborative significance when
 not itself conclusive4  ,the absence of
 forest beds and of all traces of       
vegetal deposits whatsoever between beds
 of drift1 is no proof of the absence of
 recurrent ice epochs1 since the second 
advance of the ice might have destroyed 
all trace of the prexistent soil and its
 vegetal life4 ,it is always possible1  
too1 that such beds exist1 even if they 
have not been discovered4 ,it would have
 been anticipated that they would not be

 abundant1 or wide spread4 ,the absence 
of forest beds is therefore at best no  
more than negative evidence4  7#b7      
,remains of ,land ,animals4 ,bones of   
mammalia or remains of other land       
animals1 occurring in relations similar 
to those in which forest beds occur1 may
 have a like significance4 ,their value 
as a criterion of separate glacial      
epochs is subject to essentially the    
same limitations as forest beds4  7#c7  
,inorganic ,products formed during a    
time of ,ice ,recession4 ,the recession 
of the ice after a maximum of advance   
would leave a land surface more or less 
affected with marshes and ponds4 ,in    
such situations1 bog iron ore might     
accumulate1 if conditions were          
favorable4 ,such ore beds1 buried by the
 drift of a later ice advance1 would    
have a significance comparable to that  
of forest beds1 except that they would  
give less definite information as to    
climate1 and would be correspondingly   
less trustworthy4 ,should such ore beds 

be found in such relations as to prove  
that the underlying and overlying bodies
 of drift were deposited by ice sheets  
which extended great distances further  
south1 their significance would be      
enhanced4 ,from the thickness of the ore
 beds some inference might be drawn as  
to the length of time concerned in their
 accumulation4 ,but because of the      
variable rate at which bog ore may      
accumulate1 such inference should be    
used with caution4  ,concretions of iron
 oxide might be formed in the marshes or
 in ill-drained drift areas where       
accumulations of greater extent were not
 made4 ,a subsequent incursion of the   
ice might incorporate these nodules with
 its drift1 wearing and striating them  
as other stones1 and depositing them as 
constituent parts of the later drift4   
,such iron nodules in the later drift   
would mean a recession and re-advance of
 the ice with some considerable interval
 between1 although not necessarily an   
interval sufficiently warm or long to be

 regarded as an interglacial epoch4#ae  
,calcareous concretions1 like those of  
the loess1 would possess a like         
significance1 in like relations4 ,while 
in themselves these inorganic products  
of a time of ice recession might fail to
 be conclusive of separate ice epochs1  
they might have much corroborative      
significance when associated with other 
phenomena4 ,an inter-till iron ore bed1 
associated with a forest bed which      
indicated a warm climate1 would be most 
significant4  #ae ,this point concerning
 iron nodules was suggested to the      
writer by ,mr4 ,w4 ,j4 ,mc,gee4  ,the   
absence of knowledge of ore beds between
 sheets of till1 and the absence from an
 upper bed of till of concretions of    
iron and lime carbonate formed during a 
recession of the ice1 would be no proof 
that interglacial epochs did not occur4 
,these products were probably formed in 
relatively few localities4 ,they stood  
good chance of destruction at the hands 
of the returning ice1 and they may      

exist1 where they have not been         
discovered1 or where their significance 
has not been understood4 ,their absence 
is at best no more than negative        
evidence4  7#d7 ,beds of ,marine and    
,lacustrine ,origin4 ,if between beds of
 glacial drift there be found beds of   
lacustrine or of marine origin1 such    
beds would indicate a recession of the  
ice during their time of deposition4    
,their position would be a minimum      
measure of ice recession4 ,if such      
lacustrine beds contain organic remains1
 they will bear testimony concerning the
 climatic conditions which existed where
 they occur1 at the time of their       
deposition4 ,if the fossils in such beds
 denote a temperate climate1 or a       
climate as mild as that of the present  
day in the same region1 the ice must    
have receded so far to the northward as1
 in our judgment1 to constitute its     
re-advance a distinct ice epoch4 ,this  
line of argument may be even stronger   
than that drawn from remains of         

terrestrial life1 since the ice would   
probably affect the temperature of the  
sea to greater distances than that of   
the land1 and affect it to a greater    
degree within a given distance4 ,the    
argument becomes stronger the further   
north the inter-drift marine and        
lacustrine deposits occur1 since the ice
 must always have receded to a position 
still further north4 ,if marine or      
lacustrine beds lying far north of the  
later ice limit contain proof of        
temperate climate1 the argument becomes 
conclusive4  ,the absence of marine and 
lacustrine deposits between beds of     
drift1 would be no proof that           
interglacial epochs did not occur4      
,lacustrine beds could be made only     
where there were lakes1 and lakes would 
be the exception rather than the rule4  
,marine beds in similar positions would 
rarely be known1 except where a definite
 succession of changes of level has     
taken place4 ,both classes of deposits1 
if once formed1 would be subject to     

destruction by the over-riding ice of a 
later epoch1 if such there were4        
,neither would be likely to be preserved
 at all points where formed1 and both   
may exist at many points where their    
existence is not known4 ,the absence of 
these beds is at best no more than      
negative evidence4  7#e7 ,beds of       
,subarial ,gravel1 ,sand and ,silt4     
,layers of stratified drift between     
layers of ground moraine are of common  
occurrence in many regions4 ,under      
ordinary conditions their existence is  
not regarded as evidence that the       
underlying and overlying tills are to be
 referred to separate ice epochs4 ,but  
it is conceivable that beds of          
stratified drift may1 under the proper  
circumstances and relations1 be strong  
evidence of separate ice epochs4 ,the   
last stages of ice work in the glacial  
period were accompanied1 in many        
regions1 by the deposition upon adjacent
 land surfaces1 of extensive bodies of  
gravel and sand1 washed on beyond the   

ice by waters issuing from it4 ,except  
in valleys through which strong currents
 coursed1 such deposits were apparently 
not carried far beyond the edge of the  
ice4 ,but as the edge of the ice        
withdrew to the northward1 sand plains  
may have extended themselves in the same
 direction1 by additions to their       
ice-ward faces4 ,it is conceivable that 
the process of subarial plain building  
at the edge of a receding phase of ice1 
might be carried so far under favorable 
circumstances1 as to result in the      
construction of plains of great extent4 
,in this event1 a subsequent ice-advance
 might overspread such plains in such   
wise as to bury1 without destroying     
them1 though such a course of events    
would certainly be exceptional4 ,in     
order to constitute the interstratified 
gravel and sand evidence of separate    
ice-epochs1 its continuity for great    
distances between beds of till1 and in  
the direction of ice movement1 would    
need to be demonstrated4 ,in themselves1

 these beds1 under the conditions       
indicated1 would simply be a minimum    
measure of the amount of ice recession  
between the deposition of the underlying
 and overlying bodies of till4 ,it is   
hardly likely1 though possible1 that the
 continuity of interbedded gravel and   
sand could be proved for a sufficient   
distance north of the southern limit of 
the less extensive bed of ground        
moraine1 to alone constitute evidence of
 a recession of ice great enough to make
 it necessary to refer its re-advance to
 a new epoch4 ,beds of silt in like     
relations1 deposited by waters beyond   
the edge of the ice1 would have a like  
significance so far as the question here
 under consideration is concerned4 ,such
 beds of stratified drift might         
sometimes have corroborative value when 
their testimony1 taken by itself1 is    
inconclusive4 ,if1 for example1 their   
surfaces are marked by forest beds1 and 
especially by forest beds whose plants  
denote a warm climate1 the association  

becomes most significant4  ,in view of  
what has been said1 it is evident that  
the absence of beds of subarially       
stratified silt1 sand1 and gravel1      
between beds of till can not be brought 
in evidence against separate ice epochs4
 ,it would rarely be true that          
topographic and hydro-99graphic         
conditions would make possible the      
construction of plains of sufficient    
extent to serve as criteria for the     
purpose here indicated1 and few of those
 formed would escape such a degree of   
destruction as to leave them            
demonstrably continuous4 ,there is also 
the further possibility that such beds  
exist1 even though their continuity be  
not known4 ,to prove the continuity of a
 buried bed of stratified and incoherent
 drift1 even if it existed1 would be a  
most difficult task4  7#f7 ,differential
 ,weathering4 ,if1 after covering a     
given region1 the ice retreated1 the    
drift which it left in the area which it
 previously covered would be subject to 

oxidation1 leaching and disintegration4 
,the depth to which this oxidation1     
leaching and disintegration would       
extend1 would be dependent upon the     
length of time during which the drift   
was exposed1 and upon the climate which 
affected the region during its exposure4
 ,the longer the exposure and the warmer
 the climate1 the deeper would the      
weathering extend4 ,if1 subsequently1   
the ice extended over the same region1  
it might1 in some places1 override and  
bury the old surface without destroying 
it4 ,the earlier oxidized and leached   
drift would thus come to be buried by   
the newer1 unoxidized1 unleached drift4 
,if1 therefore1 beneath the newer drift 
of any given locality there be found a  
lower drift1 the surface of which is    
oxidized and leached to a considerable  
depth1 the evidence is strong that the  
lower drift was exposed for a long      
period of time before the upper drift   
was deposited upon it4 ,within certain  
limits a similar result might be brought

 about1 it is true1 if the ice1 after   
having reached a certain maximum stage  
of advance1 were to retreat for a short 
distance only and there remain for a    
very long period of time4 ,a subsequent 
minor advance might bury the oxidized   
surface of the drift beyond the position
 of the long ice-halt4 ,under these     
conditions1 the climate which would have
 obtained in the area of the drift      
exposed during the minor retreat would  
have been cold1 and oxidation1 leaching1
 and disintegration would have proceeded
 slowly4 ,if they reached considerable  
depths1 the time involved must have been
 very long4 ,if this surface of oxidized
 and leached and disintegrated drift    
were found to reach far to the northward
 beneath the layer of newer and upper   
drift1 it would indicate a great        
recession of the ice4 ,we maintain that 
if it were found sufficiently far north 
of the margin of the overlying drift1   
and if its depth were sufficiently      
great1 extending well down below any    

possible accumulation of superglacial   
till1 it might be a positive criterion  
of so great a recession of the ice1     
protracted through so great an interval 
of time1 as to constitute its new       
advance a separate ice epoch4  ,there is
 much reason to believe that the soil   
developed under the influence of a warm 
climate differs in some respects from   
one developed from similar material     
under other conditions4 ,the well-known 
fact that red and reddish soils are     
especially characteristic of low        
latitudes and warm climates is          
significant4 ,if therefore a soil       
developed on the surface of one sheet of
 drift and buried by another1 be found  
to possess1 in addition to unmistakable 
marks of long exposure1 the peculiar    
marks which seem to be characteristic of
 soils developed under high             
temperatures1 the argument gains in     
strength4  ,this argument from oxidation
 and weathering has another application4
 ,if in a later advance1 following a    

protracted recession1 the ice-sheet     
failed to reach the limit of its earlier
 advance1 there would remain an area of 
drift deposited by the first ice-sheet1 
outside the drift deposited by the      
later4 ,now if the time interval between
 these two advances was great1 and      
especially if during this interval the  
climate was mild1 the oxidation and     
weathering of the older drift surface   
would be markedly different in degree   
from that of the newer4 ,if1 under these
 circumstances1 the surface of the older
 sheet were found to be weathered and   
oxidized and reddened up to the border  
of the newer drift sheet1 and if here   
there were found to be a sudden change  
in the character of the surface of the  
drift so far as depth and degree of     
oxidization and weathering is concerned1
 we should have strong evidence that the
 one sheet of drift was much older than 
the other4 ,the statement sometimes     
urged that the drift which was deposited
 near the edge of the greatest ice      

advance would be largely made up of the 
residual materials which occupied the   
surface invaded by the ice1 would not   
meet the case4 ,for if it be granted    
that this statement is qualitatively    
good1 we should find the greatest degree
 of weathering and oxidation at the     
extreme margin of the drift1 and it     
should be found to be less and less on  
receding from this margin4 ,there would 
in this case be no sudden transition    
from a deeply weathered and oxidized    
surface1 to one which is fresh and      
unoxidized1 along a definite line4 ,we  
maintain that if the whole of the drift 
deposits are referable to one epoch1    
there should be no sudden transition in 
the surface of the drift from that which
 is deeply weathered to that which is   
not1 the one surface being separated    
from the other by a definite and readily
 traceable line4  ,it has been urged    
against the criterion of differential   
weathering that superglacial material is
 or may be thoroughly oxidized before   

its deposition1 and that a layer of     
oxidized drift between layers of till   
may be no more than superglacial debris 
deposited during a minor recession of   
the ice4#af ,we believe that this       
attempt to eliminate the value of this  
criterion rests partly on an exaggerated
 idea concerning the amount of          
superglacial material1 but more         
especially on a failure to apprehend the
 real meaning of the argument for the   
validity of the criterion1 and upon a   
failure to note the limitations imposed 
upon it by its advocates4 ,it is not    
affirmed that a layer of oxidized drift 
between beds of unoxidized drift is per 
se proof of two glacial epochs2 but it  
is affirmed that if such layer of       
weathered drift can be shown to extend  
far below any possible superglacial     
till1 into the subglacial till below1 in
 such wise as to indicate that it is the
 result of subarial exposure in a warm  
climate subsequent to its deposition and
 prior to the deposition of the         

overlying till1 it constitutes the best 
possible evidence of an interglacial    
epoch1 especially when accompanied by   
the corroborative testimony of other    
criteria4 ,it is further affirmed that  
if the second sheet of drift failed to  
reach the limit of the first1 and if the
 drift which was deposited by the first 
and never covered by the second         
ice-sheet1 is more thoroughly and more  
deeply weathered than that deposited by 
the second1 and especially if the two   
types of drift surface meet along a     
definite and readily traceable line1 the
 argument becomes1 in our judgment1     
irrefragable4 ,in its application1 this 
criterion would be infallible only in   
the hands of one who could distinguish  
between superglacial and superglacially 
oxidized material on the one hand1 and  
material subarially weathered after its 
deposition1 on the other4  #af ,this    
point was urged at the reading of the   
paper at ,ottawa1 by ,prof4 ,c4 ,h4     
,hitchcock1 ,mr4 ,upham1 and others4    

,in circumstances and relations where   
the weathering of the drift is not in   
itself conclusive1 it might still have  
corroborative value in association with 
other lines of evidence4  ,the absence  
of an oxidized and disintegrated zone of
 drift below a superficial layer which  
is not oxidized1 would be no proof that 
there were not distinct ice epochs1     
since the ice of any later epoch1 if    
such there were1 might have planed off  
the surface of the drift left by its    
predecessor to the depth of the         
weathering4 ,the preservation of such   
surfaces after a second ice invasion    
must be regarded as the exception rather
 than as the rule4 ,there is always the 
possibility1 too1 that an oxidized and  
weathered zone marking the surface of an
 older drift sheet exists1 where        
excavations have not opened full        
sections of drift to view4 ,the absence 
of weathered zones of drift beneath the 
surface1 or the absence of knowledge of 
their existence1 is therefore at best no

 more than negative evidence4 ,the      
absence of greater weathering of the    
drift outside the limit of the drift    
supposed to belong to a later epoch1    
would be positive evidence against the  
reference of the two sheets of drift    
concerned to different epochs4  ,a      
specific part of the above line of      
evidence may be separately mentioned4   
,one phase of weathering is the         
disintegration of boulders1 and this is 
a point which can be readily applied    
even by those who are not geologists4   
,if the boulders of one region are much 
more commonly disintegrated than those  
of another1 and if the two regions are  
separated from each other by a          
well-marked boundary line1 the inference
 lies close at hand that the boulders in
 the one case have been much longer     
exposed to disintegrating agencies than 
in the other4 ,it is no answer to this  
argument to say that the materials lying
 at the very front of the drift deposits
 contain boulders which were derived    

from the disintegrated rock over which  
the ice has passed1 and that they were  
therefore in a less firm state at the   
outset4 ,in many cases these boulders   
have come from great distances1 and     
coming from great distances they must   
have come in a firm and solid state1    
else they could not have suffered such  
extensive transportation1 except indeed 
their position was superglacial         
throughout their whole journey4 ,this   
argument has equal force when applied to
 the area covered by the two sheets of  
drift where two exist4 ,if within the   
region of drift under investigation we  
find a surface layer of greater or less 
depth1 the boulders of which are hard   
and fresh1 and if beneath this we find  
another layer of drift1 the stony       
material of which is largely            
disintegrated1 at least in its upper    
parts1 we have good evidence that the   
surface bearing the disintegrated       
boulders was exposed for a considerable 
length of time before the deposition of 

the overlying drift1 which carries fresh
 boulders4 ,since the disintegration of 
boulders is only one phase of           
weathering1 the limitations of this     
argument are identical with those       
already noted in connection with the    
general argument from differential      
weathering4  7#g7 ,differential         
,subarial ,erosion4 ,if the drift       
deposited by one ice-sheet were to be   
exposed for a considerable interval of  
time1 and if the ice in its subsequent  
advance failed to reach the limit of its
 first invasion1 the two areas should   
show different amounts of subarial      
erosion1 since the one has been exposed 
to the action of air and water much     
longer than the other4 ,the line which  
marks the limit of the later ice        
invasion should be the line of more or  
less sudden transition from an area     
without1 where stream erosion has been  
greater1 to an area within1 where stream
 erosion has been less4  ,the point here
 made can not be met by the suggestion  

that the greater erosion of the outer   
area was effected by the water issuing  
from the ice which had retreated to the 
position now marked by the border of the
 area of the lesser erosion4 ,so far as 
we know1 such waters would be           
depositing1 not eroding4 ,furthermore1  
much of the erosion of the outer area   
would have such relation to drainage    
lines that waters issuing from the ice  
could never have reached the localities 
where it is shown4  ,if the outer and   
older drift be found to have suffered   
ten times as much stream erosion as the 
inner and newer1 it is fair to assume   
that it has been exposed something like 
ten times as long1 if the conditions for
 erosion are equally favorable in the   
two regions4 ,the argument has especial 
weight if it can be found that beneath  
the newer drift the surface of the older
 is such as to indicate that it was     
deeply eroded before the newer was      
placed upon it4 ,the argument is        
stronger the farther from the margin of 

the newer drift such erosion on the     
surface of the underlying older drift   
can be proved to have taken place4 ,in  
other words1 if1 in addition to the     
greater surface erosion of the older    
drift sheet as now exposed outside the  
limit of the newer drift1 we find a     
notable unconformity between the newer  
and the older drift1 and especially if  
this unconformity lie far enough north  
of the margin of the newer drift1 the   
argument becomes conclusive4  ,when     
differential erosion and drift          
unconformities are not in themselves    
conclusive1 they may have great         
corroborative value in conjunction with 
differential weathering1 forest beds1 or
 other indications of separate ice      
epochs4  ,the absence of observable     
unconformity between sheets of drift    
would be no proof that there were not   
distinct and widely separated ice       
epochs1 since the later ice invasion    
might have so far modified the surface  
which it transgressed1 as to destroy all

 patent evidences of unconformity4 ,it  
would have been anticipated that        
distinct unconformities in the drift    
would be rare1 even if there were       
distinct ice epochs1 for the same reason
 that weathered zones and forest beds   
would be rare4 ,but if the drift which  
lies outside a line supposed to mark the
 limit of a sheet of drift belonging to 
a later ice epoch1 be not more eroded   
than that which lies within such line1  
the absence of greater erosion in the   
outer drift is positive evidence against
 the reference of the drift of the two  
areas to distinct ice epochs1 if        
conditions for erosion in the two areas 
are equally favorable4  7#h7 ,valleys   
,excavated ,between ,successive         
,depositions of ,drift4 ,a closely      
related1 but not identical1 point may be
 found in the extent of the valley      
excavations which can be proved to have 
taken place between the deposition of   
the earlier and later drift4 ,we do not 
refer to valleys excavated in the drift 

especially1 but to those excavated in   
other formations as well4 ,if it can be 
shown1 for example1 that after the      
deposition of an earlier drift sheet1   
and before the deposition of a later1   
valleys were excavated which extended   
not merely into the drift itself1 but   
far beneath the drift into the          
underlying rock1 these valleys would be 
conclusive evidence of a long interval  
between the deposition of the two bodies
 of drift4 ,the argument is of especial 
force when such excavations in the rock 
beneath the drift can be shown to have  
taken place at great distances within   
the margin of the newer drift4 ,for     
valleys in such situations imply that   
the ice had receded at least as far to  
the north as they lie1 during the       
interval between the two drift          
depositions1 and may be so situated as  
to show that the ice had wholly left the
 drainage basin where they occur4  ,the 
absence of evidences of deep valley     
excavations in any given region during a

 supposed interglacial epoch1 is no     
proof that such interval did not exist4 
,the conditions may not have been       
everywhere favorable for erosion within 
the limits of any narrowly circumscribed
 area1 and the absence of interglacial  
valleys would be only negative evidence 
against an interglacial epoch4 ,the     
absence of such evidence everywhere     
would bear against the existence of an  
interglacial epoch of much duration in  
such wise as to be more than negative   
evidence4  7#i7 ,different ,directions  
of ,movement4 ,if1 after its maximum    
advance1 the ice suffered merely a minor
 recession and then remained stationary1
 or nearly so1 for a time1 the general  
direction of its movement in a          
subsequent advance would probably be    
essentially the same as in the earlier4 
,but if1 after its maximum advance1 the 
ice receded to a great distance1 and    
especially if it entirely disappeared1 a
 subsequent ice-sheet might have a very 
different direction of movement1 since  

its center of accumulation and          
dispersion might be very different4 ,it 
is conceivable that this center might   
shift during the history of a single    
ice-sheet4 ,in this case there should be
 a gradual change in the direction of   
ice movement1 not an abrupt one4 ,if1   
therefore1 there be found one sheet of  
drift made by an ice movement in one    
direction1 overlaid by another sheet of 
drift deposited by ice moving in a very 
different direction1 with an abrupt     
transition between them1 such drift     
sheets would be presumptive evidence of 
distinct ice epochs4 ,an exception would
 need to be made in the case of drift   
sheets along the margins of confluent or
 proximate ice lobes4 ,in such cases1 if
 the one lobe temporarily secured the   
advantage of the other1 drift beds      
formed by movements from opposite       
directions might be found in vertical   
succession1 without being evidence of   
separate ice epochs4  ,it is no part of 
the purpose of this essay to point out  

the difficulties which might arise in   
the application of this criterion of    
diverse directions of ice movements4 ,it
 is possible that gradual changes in the
 direction of movement might leave      
records which would seem to indicate    
abrupt changes instead4 ,this           
possibility makes care necessary in the 
application of the criterion1 but does  
not destroy its value4 ,when not itself 
conclusive1 this criterion may be so    
associated with differential weathering1
 differential erosion1 forest beds1     
etc41 that their combined testimony     
makes but one conclusion possible4  ,the
 absence of evidence of radically       
diverse directions of movement during   
the time of deposition of the various   
sheets of drift1 would be no proof that 
there were not distinct epochs4 ,in the 
first place1 the movements of different 
epochs might be harmonious--a condition 
of things more probable than any other  
if the more common views of the causes  
of glaciation be correct4 ,in the second

 place1 if the movements were diverse1  
the deposits might still be so similar  
that their differentiation1 when the one
 is buried1 might not be easily made4   
,in the third place1 the later ice might
 have so far incorporated the older     
drift material with that which belonged 
more properly to it1 as to have         
destroyed all definition between them4  
7#aj7 ,the ,superposition of ,beds of   
,till of ,different ,physical           
,constitution4 ,after the retreat of an 
ice-sheet1 the surface of the country   
thus discovered would be largely mantled
 with drift4 ,this drift would serve to 
protect the underlying rock from        
disintegration4 ,but where there was    
little or no drift1 the rock surface    
would be subject to all the disrupting  
agencies which affect surface rocks4    
,the same would be true of all rock     
surfaces bared by subarial erosion after
 the disappearance of the ice4 ,under   
these conditions1 if a second sheet of  
ice invaded the region in question after

 it had been long exposed1 it would find
 a surface prepared to yield large      
bowlders4 ,the result would be the      
deposition of a new sheet of drift      
containing bowlders much larger than    
those which would have been proper to an
 ice-sheet overspreading a surface but  
recently abandoned4 ,if1 therefore1 in  
the upper of two layers of subglacial   
till1 bowlders of great size            
predominate1 as compared with those of a
 lower homologous layer1 they may be    
indicative of a great interval of time  
between the deposition of the upper and 
lower beds of drift4 ,if the home of    
these bowlders be far north of the limit
 of the lesser sheet of drift1 the      
distance1 as well as the duration1 of   
the ice retreat must have been great1   
and the reference of the two beds of    
till to distinct ice epochs would be    
favored4 ,the case might be so strong as
 to make no other interpretation        
possible4 ,where in itself inconclusive1
 this criterion would have corroborative

 significance4 ,in its application1 the 
discrimination of subglacial and        
superglacial till would be imperative4  
,the absence of physical dissimilarity  
between superposed layers of subglacial 
till would not be proof of the absence  
of separate glacial epochs4 ,the        
phenomena constituting the criterion    
could hardly be expected to be of common
 occurrence4 ,they would never be       
obtrusive1 and may easily have escaped  
attention where they exist4#ag  #ag ,the
 #ajth criterion1 in the order here     
named1 was suggested by ,mr4 ,mc,gee in 
the discussion which followed the       
reading of the paper at ,ottawa4  7#aa7 
,varying ,altitudes and ,attitudes of   
the ,land4 ,another line of argument has
 to do with the altitude and attitude of
 the land during the deposition of      
various members of the drift complex4   
,if during the deposition of one part of
 the drift that part of the continent   
covered by the outer part of the ice was
 low1 the drainage from it would be     

sluggish4 ,if the deposits of this      
drainage persist to the present time1 we
 may find in their character evidence of
 the nature of the drainage1 and        
therefore of the attitude of the land4  
,if at a later time of drift deposition 
the glacial drainage in the same region 
was more vigorous1 the deposits made by 
the glacial streams would be            
correspondingly coarser4 ,in these      
deposits1 if they persist to the present
 day1 we should find conclusive evidence
 of the swiftness of the streams4 ,if it
 can be shown that during the deposition
 of one sheet of drift drainage was     
sluggish1 and that during the deposition
 of a later body of drift the drainage  
was vigorous1 these facts are evidence  
of an interval between the two times of 
drift deposition1 sufficiently long to  
accomplish the corresponding changes in 
elevation or attitude4 ,since such      
changes of altitude and attitude are    
generally believed to have been         
accomplished slowly1 the interval must  

be believed to have been of considerable
 duration4  ,it is true that continental
 altitudes and attitudes might change   
during a single epoch of glaciation4 ,if
 the change thus brought about resulted 
in increased slope1 the more sluggish   
drainage of the earlier part of the     
epoch would be gradually transformed    
into the more vigorous drainage of the  
later part4 ,in this case1 if the       
evidence of both the earlier sluggish   
drainage and of the later vigorous      
drainage remain1 there should also      
remain the evidence of the intermediate 
stages4 ,if the deposits representing   
the intermediate condition of drainage  
do not exist1 while those representing  
both extremes do1 there would be the    
best of reason for believing that the   
intermediate phases of drainage did not 
exist during a glacial epoch1 but during
 an interglacial epoch1 when streams    
were not handling glacial debris1 and   
when they were eroding rather than      
depositing4 ,the deposits of the slow   

and of the swift drainage might occur in
 such relations as to prove1 beyond     
peradventure1 that intermediate stages  
of glacial drainage never existed4  ,if 
the sluggish drainage accompanied the   
maximum ice invasion1 while the vigorous
 accompanied a lesser1 the evidence of  
the swift streams might be found far    
north of the southern limit of the      
earlier drift4 ,the farther north of the
 outer border of the older drift the    
gravel representing the vigorous        
drainage of the later and minor         
ice-sheet occurs1 the further the ice   
must have retreated before the change   
from the one type of drainage to the    
other was effected4 ,on the other hand1 
the farther north of the limit of the   
later ice advance the sluggish drainage 
accompanying the earlier ice-sheet may  
be traced1 the farther must the ice have
 receded before the changes resulting in
 vigorous drainage occurred4 ,under     
certain relations1 the retreat of the   
ice might be shown to have been great   

enough1 before the orographic movements 
which altered the nature of the         
drainage1 to constitute in our judgment1
 a re-advance a distinct ice epoch4 ,if 
for example throughout the course of a  
long river whose basin was largely      
covered with ice1 there be evidence that
 sluggish drainage obtained during the  
maximum ice advance1 and during all     
stages of the ice retreat until the     
basin was free from ice1 and if there be
 evidence of a vigorous glacial drainage
 in the same valley at a later time1    
with no gradations between the two      
types1 we have proof positive of at     
least a great recession1 and of a       
considerable elevation of the land after
 the ice had receded beyond the limits  
of the drainage basin and before it     
again reached it in its re-advance4 ,we 
hold that these phases of glacial       
drainage deposits may be so related to  
each other1 to the valleys in which they
 occur1 and to more or less distinct    
bodies of glacier drift1 as to prove so 

great a recession of ice between the    
diverse phases of drainage deposition1  
as to constitute the second advance a   
distinct ice epoch4  ,the absence of    
evidence that the land stood at         
different elevations during different   
parts of the period of drift deposition1
 does not in any way militate against   
the theory of recurrent and distinct ice
 epochs4 ,a constant attitude of the    
land is the thing to be assumed1 until  
positive evidence to the contrary is    
adduced4  7#ab7 ,vigor and ,sluggishness
 of ,ice ,action4 ,if it can be shown   
that during one epoch of glaciation1 we 
will say the epoch of maximum ice       
extension1 the ice action was relatively
 sluggish1 while during a later and     
minor advance its action was vigorous1  
the difference of action might be       
regarded as presumptive evidence of     
distinct ice epochs4 ,evidence of the   
two phases of ice action here referred  
to are difficult of definition1 but they
 have been independently noted by more  

than one glacialist4 ,it is true that a 
forward oscillation of the ice edge     
might be more forceful than an earlier  
forward movement which might have       
reached a greater extension4 ,in itself1
 therefore1 this line of evidence can   
not be regarded as possessing great     
value4  ,it has been indicated that     
under certain circumstances1 and in     
certain relations1 some of the foregoing
 criteria1 taken singly1 may be         
conclusive of glaciations so distinct   
from each other1 as to make their       
reference to separate epochs proper4    
,but where the facts and relations which
 constitute one of the criteria are     
found1 the facts and relations          
constituting one or more of the others  
are likely to be found as well4 ,where  
two of the foregoing criteria are found 
to be coexistent1 their joint force is  
greater than that of either one4 ,if    
neither one be absolutely conclusive1   
the two may still be1 since the one may 
exactly meet the deficiency of the      

other4 ,if three or more concurrent     
lines of evidence exist in any locality1
 the case is still further strengthened4
 ,we maintain that several of the       
foregoing criteria may be so related to 
each other and to the formations        
concerned1 as not only to make the      
recognition of separate ice epochs      
proper1 but to make the failure of such 
recognition altogether unscientific4    
,even when a single line of evidence1 or
 when double1 or triple1 or quadruple   
lines of evidence are not absolutely    
conclusive in ruling out every          
conceivable technical escape from the   
conclusion that there were separate ice 
epochs1 their cumulative and            
corroborative force may still be such as
 to carry conviction scarcely less      
positive than that which mathematical   
demonstration would afford4 ,in the     
nature of the case not all of these     
various lines of evidence could be      
expected to be found in any one         
locality1 or perhaps in any one limited 

geographic area1 but where one occurs1  
some or all of the others are liable to 
be found under favoring circumstance4   
,the number of criteria1 and the great  
extent of area where they may hope for  
application1 afford great possibilities4
  ,from the foregoing discussion1 it    
will be readily seen that the nature of 
the criteria and the limitations imposed
 upon their application by the          
difficulty of proving stratigraphic     
continuity in such a formation as the   
drift1 necessitate the greatest care in 
their use1 and reduce the value of hasty
 and inexpert conclusions to a minimum4 
,,iv4 ,areas ,where the ,criteria find  
,readiest ,application4  ,the foregoing 
criteria find their readiest application
 in regions where a later sheet of      
drift1 suspected of belonging to a later
 ice epoch1 failed to reach the border  
of an earlier sheet of drift1 suspected 
of belonging to an earlier ice epoch4   
,the #ast1 #b;d1 #c;d1 #dth1 #eth and   
#ajth as enumerated above1 find their   

application wholly within the area      
affected by the drift of the separate   
epochs1 if such there were4 ,while      
within this general area they may be    
looked for at any point1 they are likely
 to be of rare occurrence1 except along 
a somewhat narrow belt1 say #ej to #ajj 
miles1 adjacent to the border of the    
lesser ice advance4 ,the conditions for 
their occurrence and detection are      
greatly favored if the lesser drift     
sheet be the later4 ,the #fth1 #gth1    
#ith and #abth criteria might hope for  
application within the same belt1 but   
especially along a narrow zone on either
 side of the margin of the later drift  
sheet4 ,it is along this zone that the  
types of surface are thrown into        
sharpest contrast1 both as to material  
and topography4 ,the #hth and #aath     
criteria have still wider limits of     
application1 both within and without the
 border of the lesser ice advance4      
,rollin ,d4 ,salisbury4                 
,editorials4   ,it is the chief function

 of the national1 state and provincial  
geological surveys to bring forth the   
great concrete facts relative to the    
structure and resources of their several
 fields4 ,within their special domains  
they also do an important work in the   
correlation of structures and           
formations1 in the systematic           
aggregation of the facts1 in the        
organizing of results1 and in the       
development of the fundamental          
principles of geological science4 ,to   
some extent they are permitted to do    
this beyond their own fields1 but in the
 main the boundaries of these fields are
 the limits of their cordinations4 ,they
 therefore leave a great function to be 
performed by some other agency in the   
cordination of interstate1              
international1 and intercontinental     
factors4 ,they are also restrained by   
their relationships to a somewhat too   
narrowly utilitarian public from        
devoting much direct attention to the   
solution of the deeper and broader      

problems that constitute the soul of    
science1 though their contributions bear
 upon these in the most radical and     
important way4 ,in the primary work of  
systematic observation1 and the         
development of the immediate conclusions
 that spring therefrom1 these surveys   
surpass all other agencies in the value 
of their contributions to the growth of 
the science1 but in the secondary and   
ulterior work of correlation1 in the    
synthetic aggregation and organization  
of results1 and in the analytical and   
philosophical treatment of the whole1   
they need to be supplemented by agencies
 whose facilities and limitations lie in
 other lines1 agencies whose relations  
and dependencies are complementary in   
nature4 ,this secondary and ulterior    
work1 in some degree1 has been done by  
individual master students of systematic
 and philosophical geology1 but to a    
very great extent it has not been done  
at all4 ,it is a function which properly
 falls to universities1 if the          

universities can only rise to meet it2  
for it is the function of universities1 
in the larger modern view1 not only to  
rehearse science1 nor merely even to    
educate young geologists1 important as  
that is1 but to develop science for     
science's own sake1 and for its own     
inherent and permanent utilities as     
distinguished from its immediate        
applicabilities4 ,to fulfill this       
function they must not only realize and 
appreciate it1 but they must be equipped
 for field and experimental work1 as    
well as library and laboratory study4   
,ideal correlations and academic        
systematizing are as apt to be          
hindrances as helps to the progress of  
science4 ,while a few of the great      
universities of this country and ,europe
 have made notable advances in these    
directions1 the universities are1 on the
 whole1 far behind the great surveys in 
the performance of the work which       
properly falls to them4 ,this is due not
 so much to a lack of appreciation of   

the function as to the lack of          
facilities4  ,with the development of   
this higher function of the universities
 there goes a cordinate function for a  
university journal of geology1 a journal
 whose special efforts shall be devoted 
to promoting the growth of systematic1  
philosophical1 and fundamental geology1 
and to the education of professional    
geologists4 ,no part of the wide domain 
can wisely be neglected by any journal1 
but there seems to be an open field for 
a periodical which specially invites the
 discussion of systematic and           
fundamental themes1 and of international
 and intercontinental relations1 and    
which in particular seeks to promote the
 study of geographic and continental    
evolution1 orographic movements1        
volcanic cordinations and               
consanguinities1 biological developments
 and migrations1 climatic changes1 and  
similar questions of wide and           
fundamental interest4 ,this field is not
 likely to be successfully cultivated   

except by a systematic endeavor1 pursued
 through a period of years1 to bring    
together the latest and best summations 
of the results attained in the several  
national fields in a common medium1     
where they can be compared and          
discussed1 and where tentative          
correlations will suggest themselves1   
out of which1 in turn1 working          
hypotheses will naturally spring1       
leading on to such direct investigations
 as the nature of each question invites4
 ,it would be presumptuous to assume    
that the ,journal of ,geology can       
cultivate with more than very partial   
success this field1 but it especially   
invites contributions of this class4    
,another phase of geology which is      
thought to stand in much need of active 
cultivation is found in the clear and   
sharp analysis of its processes1 the    
exhaustive classification of its        
phenomena1 especially on genetic bases1 
the development of criteria of          
discrimination1 the more complete       

evolution and formulation of its        
principles and the development of its   
working methods4 ,the recent opening of 
new fields of research and the rapid    
progress of several new and important   
departments of the science give peculiar
 emphasis to this need4 ,the rising     
generation of geologists1 the hope of   
the science1 should be schooled in these
 latest and most critical aspects of the
 science4 ,a department of the ,journal1
 entitled ,studies for ,students1 has   
been opened for the special cultivation 
of this field and for its adaptation to 
advanced students and progressive       
teachers of geology4 ,mere elementary   
presentations of processes and          
principles are not desired1 but         
searching and critical expositions are  
solicited suited to the needs of young  
geologists who seek the highest         
professional equipment1 and to          
progressive teachers who desire the     
fullest practicable command of the      
newest developments of the subject4     

,these contributions may not be without 
their value to those who have already   
borne a considerable part of the heat   
and burden of life's professional day4  
,it is our desire to open the pages of  
the ,journal as broadly as a due regard 
for merit will permit1 and to free it as
 much as possible from local and        
institutional aspects4 ,it will have the
 very important advantage of being      
published under the auspices and        
guarantee of the ,university of         
,chicago1 and will be free from the     
usual financial embarrassments attending
 the publication of a scientific        
magazine4 ,this necessarily imposes upon
 the local editors the immediate        
responsibility for its editorship4      
,beyond this1 it is hoped that its      
institutional relationship will         
disappear entirely in an earnest effort 
to promote the widest interests of the  
science4 ,as an earnest of this wider   
effort several eminent geologists1      
representing some of the leading        

universities of this country1 and some  
of the great geological organizations of
 ,europe1 have kindly consented to act  
as associate editors4                   
,t4 ,c4 ,c4  ,illustration  ,upon       
invitation of the ,world's ,congress    
,auxiliary of the ,world's ,columbian   
,exposition committees were appointed by
 the several sections of the ,american  
,association for the ,advancement of    
,science at its ,rochester meeting to   
coperate with it in completing the      
organization of scientific congresses to
 be held at ,chicago in connection with 
the forthcoming ,world's ,fair4 ,the    
committee appointed by the geological   
and geographical section consisted of   
,thomas ,c4 ,chamberlin1 ,john ,c4      
,branner1 ,grove ,k4 ,gilbert1 ,w4 ,j4  
,mc,gee1 ,rollin ,d4 ,salisbury1 ,eugene
 ,a4 ,smith1 ,charles ,d4 ,walcott1 ,j4 
,f4 ,whiteaves1 ,geo4 ,h4 ,williams1 ,h4
 ,s4 ,williams and ,n4 ,h4 ,winchell4   
,it has been arranged that this         
committee should undertake the work of  

preparing the scientific program for the
 ,geological ,congress4 ,the committee  
have prepared a provisional schedule of 
topics1 which they have submitted to the
 ,advisory ,council for revision4 ,it   
has seemed to the committee that all    
contributions should be such as to have 
an international interest4 ,preferably1 
they should be subjects that can only be
 treated most advantageously in such a  
congress1 especially those that involve 
the bringing together of data from      
different lands for comparison4 ,the    
committee suggest the organization of   
the subjects under the following general
 classes3  ,first4 ,such as shall show  
the present state of geological         
progress4 ,it is believed that this can 
best be done by an exhibition of        
geological maps which shall show the    
latest and best results of official and 
other surveys4 ,as such maps will be    
prepared1 it is hoped1 for the ,world's 
,fair1 duplicates can be made at a      
slight expense for the use of the       

,congress4 ,it is hoped that each       
country that has made any notable       
progress in mapping its geological      
formations will furnish for the         
,congress at least a general geological 
map1 if not also special or analytical  
maps4  ,second4 ,such subjects as bear  
upon continental growth and             
intercontinental relations4 ,it is      
proposed to make this a leading line of 
discussion during the ,congress1 in the 
belief that there is no subject more    
appropriate1 and that there is none     
which better represents the present     
efforts of geologists or commands a more
 general interest4 ,it is hoped that    
analytical maps will be prepared by the 
geologists of the several countries     
representing the stages of growth of    
these regions in each of the great eras 
from the ,archean to the ,pleistocene1  
and that such analytical maps may       
constitute a leading feature of the     
several presentations4 ,among the       
subjects upon which contributions are   

specially invited are the following3    
,the correlation of continental and     
intercontinental orographic movements   
and geographic accretions by            
sedimentation2 ,the cordination of      
periods of vulcanism in the different   
countries2 ,the cordination of climatic 
states and changes2 ,the correlation of 
faunal and floral variations and        
migrations4 ,it is hoped that one       
session may be devoted to such          
cordination papers bearing upon each of 
the great subdivisions3 viz41 ,archean1 
,paleozoic1 ,mesozoic1 ,cenozoic1 and   
,pleistocene4  ,third4 ,papers on       
,paleontological and ,archeological     
,geology of international scope4        
,fourth4 ,contributions to ,physical1   
,structural and ,petrological ,geology  
having international or general         
bearings4  ,fifth4 ,contributions to    
,economic ,geology having general       
bearings4  ,sixth4 ,miscellaneous papers
 of especial and general interest4  ,the
 foregoing groups are intended to       

embrace and cordinate the list of       
special themes announced in the circular
 issued by the local committee some     
months since1 except such as may be best
 suited to popular presentation1 for    
which special provision is to be made4  
,it will be determined later1 when the  
number and nature of the papers are     
ascertained1 whether all will be        
arranged so as to form a continuous     
program1 or whether sub-sections will be
 formed and two or more sessions held   
simultaneously4  ,it is the desire of   
the ,world's ,congress ,auxiliary that a
 few addresses of a popular nature shall
 be given1 with a view to stimulating an
 interest in the development of the     
science on the part of the public4      
,t4 ,c4 ,c4  ,illustration  ,extra      
copies of the articles appearing under  
the head of ,studies for ,students will 
be printed and kept on sale for the use 
of teachers and advanced classes4 ,the  
prices will be fixed as low as          
practicable1 and a standing list        

published in the advertising columns of 
the ,journal4                           
,reviews4     ,on the ,glacial          
,succession in ,europe4 ,by ,prof4      
,james ,geikie4        ,transactions of 
the ,royal ,society of ,edinburgh1 ,vol4
 ,,xxxvii41        ,part ,i4 7,no4 #i71 
#ahib1 pp4 #abg-adi 7with a map74  ,in  
this timely essay ,prof4 ,geikie reaches
 the following conclusions3  #a4 ,the   
record of the first glacial epoch is    
found in the ,weyborn ,crag of ,britain1
 and the ground moraine beneath the     
,lower ,diluvium of the continent4      
,during this epoch1 the direction of the
 ice movement in southern ,sweden was   
from the south-east to the northwest4   
,this first glacial epoch of which      
direct evidence is adduced was followed 
by an interglacial interval1 during     
which the forest-bed of ,cromer1 the    
breccia of ,htting1 the lignites of     
,leffe and ,pianico1 and certain beds in
 central ,france were deposited4 ,during
 this interglacial epoch1 the climate is

 believed to have been very mild4  #b4  
,there followed a second epoch of       
glaciation1 when the ice sheet of       
,britain became confluent with that of  
the continent4 ,this was the epoch      
during which the ice sheet reached its  
southernmost extension4 ,its depositions
 are found in the lower boulder clays of
 ,britain1 the lower diluvium of        
,scandinavia and north ,germany 7in     
part71 the lower glacial deposits of    
south ,germany and central ,russia1 the 
ground moraines and high level gravel   
terraces of ,alpine lands1 and the      
terminal moraines of the outer zone4    
,during this second glacial epoch1      
,alpine glaciers are believed to have   
attained their greatest development4    
,this epoch of extreme glaciation was   
followed by an interglacial interval1   
during which ,britain is believed to    
have been joined to the continent4      
,during this interval1 the climate      
became temperate4 ,in ,russia 7near     
,moscow7 there seems to be evidence that

 it was milder and more humid than that 
of the same region at the present day4  
,toward the close of the mild epoch1    
submergence seems to have been          
accompanied by an increasing degree of  
cold1 which finally ended in another    
glacial epoch4  #c4 ,the subsidence     
which marked the close of the second    
interglacial interval1 marked likewise  
the inauguration of the third glacial   
epoch4 ,its work is represented in      
,britain by the upper boulder clay1 in  
,scandinavia and ,germany by the lower  
diluvium 7in part71 in central ,russia  
by the upper glacial series1 in ,alpine 
lands by ground moraines and gravel     
terraces4 ,the ice sheets of            
,scandinavia and ,britain were again    
confluent1 but did not extend quite so  
far south as during the second glacial  
epoch4 ,this third glacial epoch is     
believed to have been followed by       
another interglacial interval1 during   
which fresh water alluvia1 lignite and  
peat accumulations were made4 ,these are

 represented by the interglacial beds of
 north ,germany1 and by some of the     
so-called post-glacial alluvia of       
,britain4 ,there were also marine       
deposits on the coasts of ,britain and  
on the borders of the ,baltic4 ,during  
this interglacial interval1 ,britain is 
believed to have been continental4 ,the 
climate was temperate1 but in the course
 of time became more severe4 ,this      
increasing severity seems to have been  
accompanied by submergence1 which       
amounted to something like #ajj ft4     
below the present sea-level on the      
coasts of ,scotland4 ,the ,baltic       
provinces of ,germany were also invaded 
by the waters of the ,north ,sea4  #d4  
,there followed a fourth period of      
glaciation1 during which the major part 
of the ,scottish ,highland was covered  
by an ice sheet4 ,local ice sheets      
existed in the southern uplands of      
,scotland and in mountain districts in  
other parts of ,britain1 and the great  
valley glaciers sometimes coalesced on  

the low lands4 ,icebergs floated out at 
the mouths of some of the highland      
sea-lochs4 ,in some places1 terminal    
moraines were deposited upon marine beds
 which were then in process of          
formation4 ,these beds are now #ajj ft4 
above the sea level4 ,at this time      
,scandinavia was covered by a great ice 
sheet1 which yielded icebergs to the sea
 along the whole west coast of ,norway4 
,the ground moraines and terminal       
moraines of the mountain regions of     
,britain represent the deposits of this 
ice epoch4 ,the upper diluvium of       
,scandinavia1 ,finland1 and north       
,germany represent the work of the      
contemporaneous1 but not confluent1 ice 
sheet of the continent4 ,in the ,alps1  
terminal moraines in the large          
longitudinal valleys were made at the   
same time4  ,this fourth glacial epoch  
was followed by a fourth interglacial   
interval1 during which fresh water      
alluvial deposits were made1 and also   
the lower buried forest and peat of     

,britain and northwestern ,europe4 ,at  
this time1 ,scotland seems to have stood
 #de to #ej feet lower than now1 and    
,carse clays and raised beaches         
represent the work of the sea4 ,during  
this interglacial interval1 ,britain is 
believed to have become again           
continental1 while the climate became so
 far ameliorated as to allow the growth 
of great forests4 ,subsequently the     
insulation of ,britain was effected1 and
 this was followed by a climate which   
was probably colder than the present4   
#e4 ,the severity of the climate which  
marked the close of the fourth          
interglacial interval was such as to    
bring about local glaciation in some of 
the mountain valleys of ,britain4 ,here 
and there the glaciers projected their  
moraines so far down the mountains that 
they rest on what is now the #de to #ej 
feet beach4 ,in the ,alps1 this fifth   
epoch of glaciation is represented by   
the so-called post-glacial moraines in  
the upper valleys4 ,this is believed to 

have been the last appearance of        
glaciers in ,britain4 ,the dissolution  
of these glaciers was again followed by 
an emergence of the island1 and by more 
genial climatic conditions4  ,in support
 of his conclusions1 ,prof4 ,geikie     
cites some striking facts which are not 
so widely known as they should be4 ,for 
example1 ,swedish geologists have found 
evidences that there was an ice sheet   
antedating that which deposited the     
lower diluvium1 and that during this    
earlier glaciation the direction of ice 
movement in southern ,sweden was from   
the south-east to the north-west4 ,the  
ground moraine deposited by this ice    
sheet is overlain by the lower diluvium 
which was produced by an ice movement   
from the north north-east to the south  
south-west1 or nearly at right angles to
 the first4 ,again1 near ,moscow1 there 
exist interglacial beds whose plant     
remains indicate a climate milder and   
more humid than that of the present     
time4 ,these interglacial beds1 it will 

be observed1 occur in the region of the 
lower diluvium quite beyond the margin  
of the ice which produced the upper     
diluvium of ,germany and ,scandinavia4  
,during this interglacial interval1     
,prof4 ,geikie maintains that no part of
 ,russia could have been covered with   
ice4 ,if1 then1 within the limits of the
 area covered by the lower diluvium1 and
 not by the upper1 distinct beds of     
glacial drift are separated by such beds
 as those cited1 there can be no        
question but that such separation marks 
two distinct glacial epochs4 ,if there  
was an earlier glaciation when the      
movement of the ice in ,sweden was at   
right angles to that during which the   
lower part of the lower diluvium was    
produced1 this also would seem to be    
good evidence of three ice epochs prior 
to the upper diluvium4 ,the epoch of the
 upper diluvium would then constitute   
the fourth glacial epoch1 and this is   
the interpretation of ,prof4 ,geikie4   
,outside the area of the ,european      

continental ice sheet1 facts are adduced
 in striking confirmation of the        
multiple ice epoch theory4 ,these facts 
are found in ,switzerland1 where        
evidences of multiple glaciation have   
been recognized1 and in the ,pyrenees   
where evidences of three separate ice   
epochs have been found4 ,in ,france1    
evidences of an interglacial interval   
have been found in the region of the    
,puy de ,dme of such duration as to     
allow the excavation of valleys to a    
depth of #ijj feet4 ,the length of time 
which would be required for such        
stupendous erosion must certainly be    
regarded as sufficient to allow the     
preceding and succeeding glaciations to 
be considered as belonging to two       
distinct epochs4  ,another point of     
great significance and interest which   
,prof4 ,geikie's essay brings out1 is   
the correlation in ,britain between     
epochs of glaciation and epochs of      
subsidence on the one hand1 and between 
interglacial intervals and epochs of    

elevation on the other4 ,if ,prof4      
,geikie's interpretation be well        
founded1 and so far as we are able to   
judge from the facts presented this is  
the case1 his conclusions would seem to 
be fatal to the hypothesis that glacial 
climate was produced by northern        
elevation4  ,the map which ,prof4       
,geikie gives1 showing the limit of ice 
advance during the fourth glacial epoch1
 seems to us open to criticism4 ,on the 
ground of personal observation1 the     
writer believes that the ice sheet of   
the glacial epoch here represented did  
not extend notably1 if at all1 beyond   
the ,baltic ,ridge4#ah  #ah ,see        
,american ,journal of ,science1 ,may1   
#ahhg4 ,in a recent letter1 ,prof4      
,geikie indicates that he is convinced1 
from subsequent personal observation1   
that his map is erroneous so far as the 
limit of the ice of this epoch is       
concerned4 ,the mapping given was based 
on the opinion of others4  ,prof4       
,geikie is an advocate of ,dr4 ,croll's 

astronomical theory of glacial climate1 
and thinks that even five is not the    
full number of glacial epochs belonging 
to the ,pleistocene period4 ,he believes
 there may have been a series of glacial
 epochs increasing in severity to a     
maximum represented by what is now      
designated as the second glacial epoch4 
,this maximum was followed by a series  
of epochs of diminishing severity1      
represented by what he designates the   
third1 fourth and fifth epochs4 ,the    
essay is a timely contribution to       
glacial geology4                        
,rollin ,d4 ,salisbury4                 
,analytical ,abstracts of ,current      
,literature4#ai  #ai ,abstracts in this 
number are prepared by ,henry ,b4       
,kummel1 ,chas4 ,e4 ,peet1 ,j4 ,a4      
,bownocker4     ,the ,sub-,glacial      
,origin of ,certain ,eskers4 ,by        
,william ,morris        ,davis1 ,harvard
 ,university4 7,proceedings of the      
,boston ,society        of ,natural     
,history1 ,vol4 ,,xxv41 ,may #ah1       

#ahib74  ,a critical discussion of the  
conditions under which it is conceived  
certain eskers and sand plateaus        
7plains7 were formed4 ,the ,auburndale  
district1 ten miles east of ,boston1    
presents three classes of modified drift
 deposits2--sand plateaus1 eskers1 and  
kames4 ,these deposits are well exposed4
  ,the sand plateaus have the           
characteristics of delta deposits of    
glacial streams1--even surfaces1        
well-bedded sands and gravels1 the beds 
sloping outward from the head at an     
angle of #ab to #bj1 and in close       
agreement with the slope of the plateau 
front1 a lobate margin1 deposits        
distinctly coarser at the head than near
 the front1 and a series of nearly      
horizontal roughly cross-bedded gravels 
overlying the sloping beds4  ,the eskers
 are essentially of the same material as
 that of the plateau1 often so poorly   
stratified as to render differentiation 
of the beds difficult4 ,the interstices 
between the pebbles are often unfilled1 

although there is abundance of fine     
material in adjoining layers4 ,this open
 work is taken to indicate rapid        
deposition1 and seems to preclude the   
supposition that the gravels have       
settled down from a superglacial        
position1 or been traversed by currents 
of any volume4 ,in several instances the
 eskers can be followed to direct union 
with sand plateaus4 ,towards its lower  
end the esker frequently gives out      
branches and the adjacent lowland       
surface becomes more or less encumbered 
with sand mounds or kames1 indicating a 
decayed margin of the ice4  ,prof4      
,davis' conclusions are3  #a4 ,the      
eskers and sand plateaus of ,auburndale 
and ,newtonville were formed by running 
water just inside and outside of the ice
 margin in the closing stage of the last
 glacial epoch4  #b4 ,the ice-sheet was 
a stagnant1 decaying mass at the time of
 their formation1 as is shown by the    
ragged outline of its margin4  #c4      
,eskers and sand plateaus are           

genetically connected2 the term1        
feeding-esker1 is fully warranted by the
 relation of the two in position1       
structure1 and composition4  #d4 ,the   
sand plateaus were made rapidly2 this is
 proved by the absence of disordered    
beds at their heads1 where space would  
have been opened by the backward melting
 of the ice had the forward growth of   
the plateau been slow4 ,the eskers were 
also made rapidly1 as is shown by their 
'open-work gravels4'  #e4 ,the diversion
 of the feeding streams to other outlets
 left the plateaus and the eskers       
without further energetic action as the 
ice melted away from them4  #f4 ,the    
present form and structure of the eskers
 are more accordant with the supposition
 of a subglacial origin than of a       
superglacial origin2 but it is not      
intended to imply that other eskers of  
more irregular form and different       
structure could not have been deposited 
in superglacial channels4               
,h4 ,b4 ,k4                     99      

99       99       99       99           
,studies in ,structural ,geology4 ,by   
,bailey ,willis1 ,u4 ,s4 ,geol4         
,surv4 7,transactions of the ,american  
,institute of ,mining        ,engineers1
 ,june1 #ahib74  ,the paper aims to     
present some of the results of          
observation of the geologists of the    
,appalachian division during the past   
three years on the subject of structural
 geology in the ,appalachian province4  
,the structural features are all of one 
type but of different phases1 comprised 
in four great districts4 #a7 the        
district of close folding1 #b7 a        
district whose chief structural         
characteristic is cleavage1 #c7 a       
district of open folding1 #d7 a district
 of faulting and folding4 ,the answer to
 the questions1 ,why did the strata bend
 in the district of open folding1 and   
why did they break in the district of   
faulting1 is that the thrust affected   
them according to their rigidity under  
their respective conditions of          

superincumbent load4 ,we know that load 
up to a certain point restrains fracture
 in material under thrust4 ,in the      
district of open folding the ,devonian  
limestone is the most rigid of the      
strata and the one which would most     
effectively transmit the compressing    
thrust and would control the resulting  
structure4 ,in the district of open     
folding this limestone was prevented    
from breaking and faulting by a load of 
superincumbent strata exerting a        
pressure of #aj1jjj to #bc1jjj pounds   
per square inch1 while in the faulted   
district a load of #e1jjj to #aj1jjj    
pounds per square inch permitted the    
strata to break and fault4  ,the answer 
to the question1 ,why did the           
compression affect this zone1 is given4 
,it becomes apparent on study of        
sections that where compression raised a
 great arch there previously existed a  
bend from a nearly horizontal to a      
descending position in the principal    
stratum transmitting the thrust4        

,greater anticlines and synclines       
originated in upward and downward       
convexity of initial dips1 due to       
unequal deposits of sediments which     
depress underlying strata in proportion 
to their weight4 ,such folds may be     
called original4 ,the ,pottsville1      
,mahanoy1 ,shamokin and ,wyoming coal   
basins of ,pennsylvania belong to this  
class4  ,experiments have recently been 
carried on in the office of the ,united 
,states ,geological ,survey reproducing 
the different forms of folding4 ,the    
experiments differed from other         
experiments in that #a7 the materials   
used to simulate the stratified rocks   
varied in consistency from brittle to   
plastic1 according to the depth at which
 deformation is supposed to take place2 
#b7 the compression was exerted under a 
movable load representing the weight of 
superincumbent strata2 #c7 the strata   
rested on a yielding base to simulate   
the condition of support of any arc of  
the earth's crust4 ,the following are   

the conclusions from the experiments3   
#a4 ,when a thrust tangentially affects 
a stratified mass1 it is transmitted in 
the direction of the strata1 and by each
 stratum according to its inflexibility4
 ,at any bend the force is resolved into
 components1 one radial1 the other      
tangential to the dip beyond the bend2  
the radial component1 if directed       
downward1 tends to depress the stratum  
and displace its support4  #b4 ,a thrust
 so resolved can only raise an anticline
 or arch which is strong enough to      
sustain the load lifted by its          
development2 such an arch may be called 
competent2 and since strength is a      
function of the proportions of a        
structure1 it follows that1 for a given 
stratum1 the size of a competent        
anticline will vary inversely as the    
load2 or for a given load the size will 
vary as the thickness of the effective  
stratum4  #c4 ,the superincumbent load  
borne by a competent anticline is       
transferred to the supports of the arch 

at the points of inflection of the      
limbs4  #d4 ,when a competent arch is   
raised by thrust from one side1 the load
 transferred may so depress the         
resulting syncline further from the     
force that an initial dip will be       
produced in otherwise undisturbed       
strata2 this dip will rise to a bend    
from which a new anticline may be       
developed4 ,this anticline is a result  
of the first1 and may be called         
'subsequent' in distinction to original 
folds4 ,since subsequent folds are      
simply competent structures1 their size 
will be determined by conditions of     
thickness and load1 and for like        
conditions they should be equal2 and    
they must1 in consequence of conditions 
of development1 be parallel to the      
original fold and to each other4 ,an    
example of an original fold with its    
subsequent anticlines is the ,nittany   
arch and the group of parallel          
anticlines which lie southeast of it1   
extending northeast from the ,broad ,top

 basin4                                 
,c4 ,e4 ,p4                     99      
99       99       99       99     ,the  
,catskill ,delta in the ,post-,glacial  
,hudson ,estuary4 ,by ,william          
,morris ,davis4 7,from the ,proceedings 
of the ,boston ,society of              
,natural ,history1 ,vol4 ,,xxv41 #ahia74
  ,the post-,tertiary trenches of the   
,hudson and its tributaries are in the  
main filled with clay beds1 which1      
covered by a thin deposit of sand1 rise 
in terraces #acj1 #aej1 or even #ahj    
feet above tide-water4 ,these clays are 
the result of a late glacial or         
post-glacial submergence of the valley1 
but their upper surface does not        
indicate the amount of their            
submergence1 as they are bottom         
deposits4 ,delta deposits made by the   
tributary streams1 where they entered   
the ,hudson estuary1 would indicate the 
amount of submergence4  ,such deposits  
are found on the ,catskill a mile north 
of ,cairo1 and eroded remnants are      

traceable for three or four miles down  
stream4 ,the surface is characterized by
 great numbers of water-worn stones up  
to fifteen or eighteen inches in        
diameter4 ,the lobate margin1 where     
present1 is poorly defined4 ,these      
deposits range from #bij feet 7aneroid7 
above tide1 up river1 to #bgj feet      
further down4 ,one-tenth of a cubic mile
 of material seems to have been washed  
into the ,catskill trench at the point  
of this delta between the time of the   
ice departure and the elevation of the  
land4 ,subsequent terracing has removed 
half that amount4  ,the course of the   
,catskill at ,leeds1 where it crosses a 
ledge of hard ,corniferous limestone is 
probably of post-glacial superimposed   
origin1 but the preglacial valley cannot
 be definitely fixed4                   
,h4 ,b4 ,k4                     99      
99       99       99       99           
,geological ,survey of                  
,alabama4--,bulletin #d4 ,by ,c4        
,willard ,hayes4        7,report of the 

,geology of ,northeastern ,alabama and  
,adjacent        ,portions of ,georgia  
and ,tennessee74  ,this report covers an
 area of #eiej miles1 two-thirds in     
,alabama4 ,topographically it falls into
 three divisions3 #a7 the ,cumberland   
and other plateaus of the northwest2 #b7
 in the center1 anticlinal              
valleys--,browns and ,wills1 with the   
synclinal mountains--,sand and ,lookout2
 #c7 the monoclinal mountains1 the      
flatwoods 7,coosa shales7 and the chert 
hills 7,knox limestone7 of the          
southeast4 ,the drainage of the first is
 radial from the center of the plateau  
to the ,tennessee2 that of the second1  
once consequent upon the folded         
structure1 is now adjusted to the strike
 of the soft beds4  ,the formations are 
,cambrian1 ,silurian1 ,devonian and     
,carboniferous4 ,total thickness is from
 #ac1jjj to #ah1jjj feet in the east1   
but decreases westward4 ,hard sandstones
 of the ,carboniferous form the cappings
 of the plateaus and synclinal          

mountains4 ,in the anticlinal and       
monoclinal valleys the ,silurian and    
,cambrian appear4 ,the rocks pass from  
the nearly horizontal beds of the       
plateau region1 by narrow unsymmetrical 
anticlines with steeper dip on the      
northwest side1 and by broad shallow    
synclines1 to the complicated folds of  
the southeast4 ,the axes of these latter
 folds dip more or less abruptly        
northward and southward1 causing the    
ridges to assume zigzag courses4        
,synclines are often crossed by         
anticlines4  ,thrust faults exist1 some 
of great magnitude1 and traceable for   
#bjj to #cjj miles4 ,by the ,rome thrust
 fault the ,cambrian shales have been   
shoved four to five miles over upon the 
,carboniferous shales4 ,most of the     
overthrust strata have been worn away1  
but tongues of ,cambrian shale still    
remain to all appearances lying         
conformably upon the ,carboniferous     
strata4 ,transverse thrust faults       
terminate ,gaylor's ridge1 ,dirt ,seller

 ,mountain1 and ,lookout ,mountain on   
the south4                              
,h4 ,b4 ,k4                     99      
99       99       99       99     ,the  
,correlation of ,moraines with ,raised  
,beaches of ,lake ,erie4        ,by     
,frank ,leverett1 ,u4 ,s4 ,geol4 ,surv4 
7,wisconsin ,academy of        ,science4
 ,vol4 ,,viii41 #ahia74  ,references    
have been made in ,geological literature
 to the beaches of the eastern portion  
of the ,lake ,erie basin1 but up to the 
time of ,mr4 ,leverett's work none of   
the beaches had been completely traced4 
,mr4 ,gilbert had discovered that       
several of the raised beaches do not    
completely encircle ,lake ,erie1 and    
supposed that their eastern termini     
represent the successive positions of   
the front of the continental glacier    
during its retreat northeastward across 
the ,lake ,erie basin4 ,mr4 ,leverett   
verifies this theory by demonstrating   
that certain moraines are the           
correlatives of the beaches4 ,they are  

as follows3  ,i4 ,the ,van ,wert or     
upper beach and its correlative moraine1
 the ,blanchard ridge4 ,,ii4 ,the       
,leipsic or second beach and its        
correlative moraines4 ,,iii4 ,the       
,belmore1 or third beach and its        
correlative moraine4  ,i4 ,the ,van     
,wert beach extends eastward from the   
former southwestward outlet of ,lake    
,erie near ,fort ,wayne1 ,indiana1 to   
,findlay1 ,ohio1 where it joins the     
,blanchard moraine4 ,through ,indiana   
and ,ohio its altitude is quite         
uniformly #baj feet above ,lake ,erie4  
,while the ,van ,wert beach was forming1
 the ice front was the northeastern     
shore of the lake as far east as        
,findlay1 ,ohio1 its position being     
marked by the ,blanchard moraine4 ,east 
of ,findlay1 where the ,van ,wert beach 
joins it1 the moraine is of the normal  
type4 ,but west of ,findlay1 it presents
 peculiarities of topography and        
structure1 resulting from the presence  
of lake water beneath the ice margin4   

,the water was shallow and incapable of 
buoying up the ice-sheet1 and producing 
icebergs4 ,the motion of the water under
 the ice-sheet produced a variable      
structure4 ,this is the only instance of
 a moraine demonstrably formed in lake  
water4  ,,ii4 ,the ,leipsic1 or second  
beach1 was formed after the ice had     
retreated from its position marked by   
the ,blanchard moraine4 ,its altitude is
 #aie to #bjj feet above ,lake ,erie4   
,it has its terminus near ,cleveland1   
where it connects with the western end  
of a moraine4  ,,iii4 ,the ,belmore     
beach and its correlative moraine4      
,between the ,leipsic beach and the     
present shore of ,lake ,erie are several
 beaches4 ,one of these1 the ,belmore   
beach1 terminates near ,cleveland1 while
 the others extend into southwestern    
,new ,york1 and probably connect with   
moraines1 though this connection has not
 been traced4 ,the general altitude of  
the ,belmore beach in ,ohio is #afj to  
#agj feet above ,lake ,erie4 ,unlike the

 ,van ,wert and ,leipsic beaches1 it    
does not directly connect with a moraine
 at its eastern end1 but a gap of ten   
miles intervenes4 ,terraces at          
,cleveland1 ,mr4 ,leverett thinks1 make 
a connection between the eastern end of 
the beach and the western end of the    
moraine at ,euclid1 ,ohio4              
,c4 ,e4 ,p4                     99      
99       99       99       99     ,the  
,climate of ,europe ,during the ,glacial
 ,epoch4 ,by ,clement ,reid4            
7,natural ,science4 ,vol4 ,i1 ,no4 #f1  
#ahib74  ,temperature of the ,sea4--,the
 temperature of the ,english ,channel   
was similar to that where the isotherm  
of #cb ,f4 is now situated4 ,the winter 
temperature can scarcely have been #bj  
colder than at present4 ,the            
,mediterranean was perhaps #e colder    
than now4  ,temperature of the ,land    
7air74--,it does not appear that the    
climate of the lowlands of southern     
,europe can have been #bj lower than the
 present mean2 #aj or perhaps less      

appear to have been the refrigeration in
 the ,mediterranean region4 ,the        
temperature at the southern margin of   
the ice-sheet was about #bj colder than 
at present4 ,the temperature increased  
rapidly towards the south4 ,recent      
observations seem to show that          
throughout central ,europe there was a  
period of dry cold1 causing the country 
to resemble the arid regions of central 
,asia4                                  
,j4 ,a4 ,b4                     99      
99       99       99       99     ,on   
the ,glacial ,period and the            
,earth-,movement ,hypothesis4 ,by       
,james ,geikie1 ,edinburgh1 ,scotland4  
7,read before the ,victoria             
,institute1 ,london74  ,geologists      
generally admit that there have been at 
least two glacial epochs1 separated by  
one well-marked interglacial period4    
,the closing stage of the ,pleistocene  
period was one of cold conditions in    
northwestern ,europe1 accompanied by    
land depressions4 ,after this came a    

genial climate with a union of the      
,british islands among themselves and   
also with the continent4 ,this was      
followed by a cold1 humid condition4    
,upham maintains that the whole of      
,north ,america north of the ,gulf of   
,mexico stood at least three thousand   
feet higher at the beginning of the     
glacial epoch than at present4 ,fiords  
were formed before glacial times and so 
can not be cited as evidence of high    
land during the glacial period4 ,an     
elevation of land in the northern part  
of ,north ,america and ,europe could not
 produce glaciation in their southern   
parts4 ,the deflection of the ,gulf     
,stream by the sinking of the ,panama1  
,professor ,geikie argues1 could not    
produce the conditions which prevailed  
during the glacial epoch4 ,the          
,earth-,movement hypothesis1 he         
believes1 accounts neither for the      
widespread phenomena of the ice-age1 nor
 for the remarkable interglacial        
climates4 ,some maintain that the warm  

interglacial period was produced by the 
rise of the ,panama land1 the sinking of
 the lands to the north1 and the turning
 of the ,gulf ,stream from the ,pacific 
into the ,atlantic4 ,why then1 asks     
,professor ,geikie1 do we not have such 
a climate now8                          
,j4 ,a4 ,b4                             
,acknowledgments4   ,the following      
papers have been donated to the library 
of the ,geological ,department of the   
,university of ,chicago1 mainly by their
 authors3  ,abbe1 ,cleveland4    --,on  
the ,production of ,rain4 #h pp4 #ahib4 
,ami1 ,henry ,m41 ,m4,a41 ,f4,g4,s4     
--,on ,canadian ,extinct ,vertebrates4  
#d pp4--,ottawa ,naturalist4    --,on   
the ,geology of ,quebec and ,environs4  
#bf pp41 #a pl4--,bull4 ,geol4          
,soc4 ,am41 vol4 #b1 pp4 #dgg-ejb4      
--,on the ,geology of ,quebec ,city1    
,canada4 #d pp4--,canadian ,record      
,sci41        ,april1 #ahia4            
--,additional ,notes on ,ganiograptus   
,thureani1 ,mc,coy1 from the ,levis     

,formation ,canada4 #b pp4--,canad4     
,record ,sci41 ,oct4 #ahhi4             
--,reviews of ,reports and ,papers on   
,canadian ,geology and ,paleontology4   
#h pp4--,ottawa ,naturalist1 ,oct4-,dec4
 #ahib4    --,notes and ,descriptions of
 some new or hitherto unrecorded species
        of ,fossils from the            
,cambro-,silurian 7,ordovician7 ,rocks  
of the        ,province of ,quebec4 #ae 
pp4--,canadian ,record of ,sci41 ,april1
 #ahib4    --,review of ,catalogue of   
the ,fossil ,cephalopoda of the ,british
        ,museum1 ,part #h1 ,nautiloidea4
 ,by ,arthur ,h4 ,foord1 ,f4,g4,s4 #c   
pp4--,canadian ,record of ,sci41 ,sept4 
#ahia4    --,on the ,sequence of ,strata
 forming the ,quebec ,group of ,logan   
and        ,billings1 with ,remarks on  
the ,fossil ,remains found therein4 #d  
pp4--,ottawa ,naturalist1 ,june1 #ahib4 
,ande1 ,a4 and ,a4 ,osann4    --,beitrge
 zur ,geologie des ,blattes ,heidelberg4
 #ci pp41 ,,iii41 #b        pl4--,aus   
den ,mittheilungen der ,grossh4         

,badischen ,geologischen                
,landesanstalt1 ,,ii ,bd4 ,,vii-,,xi4   
,baltzer1 ,a4    --,beitrge zur         
,geognosie der ,schweizer-,alpen ber die
 ,frage1        ob der ,granit-,gneiss  
der nrdlichen ,grnzregion der           
,finsteraarhorn-,centralmass eruptiv sei
 oder nicht1 und ber        damit       
zusammenhngende ,probleme4 #da pp41 #b  
pl4--,neues ,jahrbuch        fr         
,mineralogie1 #ahgh4    --,beitrge zur  
,geognosie der ,schweizer-,alpen4 ,ueber
 die ,marmorlager        am ,nordrand   
des ,finsteraarhorn-massivs4 #bj pp41 #b
 pl4--,aus dem        ,neuen ,jahrbuch  
fr ,mineralogie1 #ahgg4    --,ueber den 
,hautschild eines ,rochen aus der       
marinen ,molasse4 #d pp41 #a            
pl4--,aus den ,mittheilungen der        
,naturforschenden ,gesellschaft in      
,bern4    --,ueber den natrlichen       
,verkohlungsprozess4 #bc pp4--,aus der  
,vierteljahrs-schrift der zrcherischen  
naturforschenden        ,gesellschaft4  
--,randerscheinungen der                

centralgranitischen ,zone in ,aarmassiv4
 #ah        pp41 #a pl4--,aus dem ,neuen
 ,jahrbuch1 #ahhe4 ,,ii ,band4          
--,beitrge zur ,geognosie der           
,schweizer-,alpen4 ,ein ,beitrag zur    
,kenntniss der ,glarnerschlinge4 #bj    
pp41 #a pl4--,aus dem ,neuen            
,jahrbuch fr ,mineralogie1 ,geol4 und   
,pal4 #ahgf4    --,geologische ,skizze  
des ,wetterhorns in ,berner ,oberland4  
#ad pp41 #b        pl41 ,zeit4 der      
,deut4 geolog4 ,gesell1 #ahgh4          
--,geognostich-chemische ,mittheilungen 
ber die neuesten ,eruptionen        auf 
,vulcano und die ,producte derselben4   
#bi pp41 #c pl4--,zeit4 d4        ,deut4
 ,geolog4 ,gesell1 #ahge4    --,ueber   
,bergstrze in den ,alpen4 #ej pp41 #a   
pl4--,aus dem ,jahrbuch des             
,s4,a4,c4 7,x4 ,jahrgang7 ,zrich1 #ahge4
  ,baker1 ,frank ,c4    --,notes on a   
,collection of ,shells from the         
,mauritius2 with a        consideration 
of the ,genus ,magilus of ,montfort4 #bb
 pp41 #a        pl4--,proc4 ,rochest4   

,acad4 ,sci41 ,vol4 #b1 #ahib4          
--,catalogue and ,synonomy of the       
,recent ,species of the ,family of      
,muricid1 ,first ,paper4 #bj pp4--,proc4
 ,rochest4 ,acad4 ,sci41 ,vol4          
,i1 #ahia4    --,description of ,new    
,species of ,muricid with ,remarks on   
the ,apices        of ,certain ,forms4  
#i pp41 #a pl4--,proc4 ,rochest4 ,acad4 
,sci41 ,vol4        ,i1 #ahia4          
,barrois1 ,charles4    --,sur la prsence
 de fossiles dans le terrain azoique4 #d
 pp4--,comptes        ,rendus des       
,sances de ,l',acadmie des ,sciences1   
,aug4 #h1 #ahib4  ,beecher1 ,c4,e41     
,ph4,d4    --,the ,development of some  
,silurian ,brachiopods4 #h pl41 #if     
pp4--,n4 ,yr        ,state ,mus41 ,vol4 
,i1 ,no4 ,i1 ,oct4 #ahib4               
--,brachiospongid1 a ,memoir on a ,group
 of ,silurian ,sponges4 #bh pp41 #f     
pl4 ,memoirs of the ,peabody ,mus41     
,vol4 ,,ii1 ,part ,i1 #ahhi4            
--,insecta by ,alpheus ,hyatt and ,j4   
,m4 ,arms4--,am4 ,jour4 ,sci41 ,march1  

#ahia4    --,new ,types of              
,carboniferous ,cockroaches from the    
,carboniferous        ,deposits of the  
,united ,states2 7#b7 ,new              
,carboniferous ,myriapoda        from   
,ill42 7#c7 ,illustrations of the       
,carboniferous ,arachnida        of ,n4 
,a41 of the orders ,anthracomarti and   
,pedipalpi2 7#d7 ,the        ,insects of
 the ,triassic ,beds at ,fairplay1      
,col41 ,samuel ,h4        ,scudder4 #b  
pp4--,am4 ,jour4 ,sci41 ,jan41 #ahia4   
--,some ,abnormal and ,pathologic ,forms
 of ,fresh ,water ,shells from the      
,vicinity of ,albany1 ,n4 ,y4 #b pp41 #b
 pl4--#cfth ,rep4 ,n4 ,y4 ,state        
,mus4 of ,nat4 ,hist4    --,the         
,development of a ,paleozoic ,poriferous
 ,coral4 ,symmetrical ,cell             
,development in the ,favositid4 #ab pp41
 #g pl4--,trans4 ,conn4 ,acad4          
,sci41 ,vol4 #h1 #ahia4    --,on        
,leptnisca1 a ,new ,genus of ,brachiopod
 from the ,l4 ,helderberg        ,group4
 ,n4 ,a4 ,species of ,strophalosia4 #h  

pp41 #a pl4--,am4 ,jour4        ,sci41  
,sept41 #ahij4    --,ceratiocarid from  
the ,chemung and ,waverly ,groups at    
,warren1 ,penn4        #bb pp41 #b      
pl4--,rep4 of ,prop41 ,,ppp1 #b;d ,geol4
 ,surv4 ,penn41 #ahhd4    --,a ,spiral  
,bivalve from the ,waverly ,group of    
,penn4 #d pp41 #a        pl4--#cith ,an4
 ,rep4 ,n4 ,y4 ,state ,mus41 #ahhf4     
--,on the ,lingual ,dentition and       
,systematic ,position of ,pyrgula4 #h   
pp41        #a pl4 ,jour4 ,n4 ,y4 ,mic4 
,soc41 ,jan41 #ahij4    --,on the       
,occurrence of ,u4 ,silurian ,strata    
near ,penobscot ,bay1 ,maine4        #f 
pp41 ,ill4--,am4 ,jour4 ,sci41 ,may1    
#ahib4    --,koninckina and ,related    
,genera4 #i pp41 #a pl4--,am4 ,jour4    
,sci41 ,sept41        #ahij4            
--,development of the ,brachiopoda1     
,part ,i1 ,introduction4 #ad pp41 #a    
pl4--,am4 ,jour4 ,sci41 ,apr41 #ahib4   
--,development of the ,brachiopoda4     
,part ,,ii1 ,classification of the      
,stages of ,growth and ,decline4 #bb    

pp41 #a pl4--,am4 ,jour4 ,sci41         
,aug41 #ahib4  ,beachler1 ,chas4 ,s4    
--,keokuk ,group of the ,miss4 ,valley4 
#h pp4--,am4 ,geol41 ,aug41 #ahib4 #c   
copies4    --,the ,rocks at ,st4 ,paul1 
,indiana and ,vicinity4 #b pp4--,am4    
,geol41        ,mch41 #ahia4 #c copies4 
,bigelow1 ,frank ,h4    --,notes on a   
new ,method for the ,discussion of      
,magnetic ,observations4        #dj pp41
 #b pl4--,bull4 ,weather ,bureau1 #ahib4
  ,boehm1 ,georg4    --,ueber den       
,fussmuskeleindruck bei ,pachyerisma4 #b
 pp4--,berichte der                     
,naturforschenden ,gesellschaft in      
,freiburg i4 ,b41 #ahib4 ,,vi4 #c4      
--,megalodon1 ,pachyerisma und ,diceras4
 #bd pp4 #i wood cuts4--,aus den        
,berichten der ,naturforschenden        
,gesellschaft ,,vi4 #b4 zu ,freiburg    
i4 ,b41 #ahia4    --,lithiotis          
,problematica4 #af pp41 #c              
pl4--,naturforschenden ,gesell4 in      
,freiburg1 ,band ,,ii4 ,heft #c4        
--,ueber das ,alter der ,kalke des col  

dei ,schiosi4 #d pp4--,der ,deut4       
,geolog4 ,gesell1 #ahhg4    --,ein      
,beitrag zur ,kenntniss der ,kreide in  
den ,venetianer ,alpen4 #af        pp41 
#d pl4 #c cuts4--,aus den ,berichten der
 ,naturforschenden        ,gesellschaft 
zu ,freiburg i4 ,b4 ,band ,,vi4 ,heft   
#d4    --,die ,bivalven der ,schichten  
des ,diceras ,muensteri 7,diceraskalk7  
von        ,kelhein4 #h pp4--,zeit4     
,deut4 ,geol4 ,gesell4 #ahha4           
--,ueber die ,fauna der ,schichten mit  
,durga im ,departement der ,sarthe4     
#ab pp41 #a pl4 #b wood cuts4--,zeit4   
der ,deut4 geol4 ,gesell4 ,bd4          
,,xl41 #ahhh4    --,die ,facies der     
grauen ,kalke von ,venetien im          
,departement der ,sarthe4        #f     
pp4--,aus der ,zeit4 der ,deut4 geol4   
,gesell1 #ahhg4    --,sdalpine          
,kreideablagerungen4 #f pp4--,aus der   
,zeit4 d4 ,deut4 geol4        ,gesell1  
,bd41 #cc1 #b ,heft4    --,ueber eine   
,anomalie im ,kelche von ,millericrinus 
mespiliformis4 #e        pp41 ,ill4     

,zeit4 der ,deut4 ,geol4 ,gesell41 ,bd4 
#dc1 ,heft #c4  ,bowerman1 ,a4    --,the
 ,chinook ,winds and other ,climatic    
,conditions of the ,northwest4 #f       
pp4--,hist4 and ,sci4 ,soc'y of         
,manitoba1 ,apr4 #bb1 #ahhf4  ,blanford1
 ,w4 ,t41 ,,ll4,d41 ,f4,r4,s4    --,on  
,additional ,evidence of the ,occurrence
 of ,glacial ,conditions        in the  
,paleozoic ,era1 and in the ,geological 
,age of the ,beds        ,containing    
,plants of the ,mesozoic ,type in ,india
 and ,australia4  ,brigham1 ,albert ,p4 
--,a ,chapter in ,glacial ,history with 
,illustrative ,notes from ,central      
,new ,york4--,trans4 ,oneida ,hist4     
,society1 #ahhi-ia4    --,the ,geology  
of ,oneida ,county4 #ah pp4--,trans4    
,oneida ,hist4 ,society1                
#ahhg-hh4    --,rivers and the          
,evolution of ,geographic ,forms4 #ba   
pp41 ,ill4--,am4        ,geog4 ,soc'y1  
,mch41 #ahib4  ,chamberlin1 ,t4 ,c4     
--,hillocks of ,angular ,gravel and     
,disturbed ,stratification4 #ab pp41    

,ill4--,am4 ,jour4 ,sci41 ,may1 #ahhd4  
,carter1 ,prof4 ,o4 ,c4 ,s4    --,ores1 
,minerals and ,geology of ,montgomery   
,county1 ,pennsylvania1 with            
map4--,hist4 of ,mont4 ,co4             
--,artesian ,wells in the ,lowest ,trias
 at ,norristown4 #g pp4--,proc4 ,am4    
,phil4 ,soc41 ,may #a1 #ahia4           
,carpenter1 ,commander ,a41 ,r4 ,n4     
--,soundings ,recently ,taken off       
,barren ,island ,narcondam1             
,pl4--,records        ,geol4 ,sur4      
,ind41 ,vol4 ,,xx1 ,part #a1 #ahhg4     
,clarke1 ,f4 ,w4    --,the ,meteoric    
,collection in the ,u4 ,s4 ,nat4 ,mus4  
,a ,catalogue of        ,meteorites     
,represented4 ,nov4 #a1 #ahhf4 #ac pp4  
,ill41 #a pl4    --,some ,nickel ,ores  
from ,oregon1 ,ill4 #g pp4--,am4 ,jour4 
,sci41 ,june1        #ahhh4             
--,tschemak's ,theory of the ,chlorite  
group and its ,alternative4 #aj         
pp4--,am4 ,jour4 ,sci41 ,march1 #ahib4  
--,on ,nephrite and ,jadeite4 #ae pp4 #a
 pl4 ,proc4 ,u4 ,s4 ,nat4 ,mus4 ,,xi1   

#ahhh4    --,studies in the ,mica       
,group4 #f pp4--,am4 ,jour4 ,sci41      
,aug41 #ahhi4    --,a ,new occurrence of
 ,gyrolite4 #b pp4--,am4 ,jour4 ,sci41  
,aug41 #ahhg4    --,experiments upon the
 ,constitution of the ,natural          
,silicates4 #be        pp4--,am4 ,jour4 
,sci41 ,oct41 ,nov41 ,dec41 #ahij4      
--,mica4 #f pp4--,min4 ,resources of the
 ,u4 ,s41 #ahhc-d4    --,note on the    
,constitution of ,ptilolite and         
,mordenite4--,am4 ,jour4        ,sci41  
,aug41 #ahib4    --,on ,some ,phosphides
 of ,iridium and ,platinum on ,cadmium  
,iodide4        ,some ,sp4 ,gr4         
,determinations4 ,researches on the     
,tartrates of        ,antimony4--,am4   
,chem4 ,jour4 ,vol4 ,v41 ,no4 #d4       
--,the ,fractional ,analysis of         
,silicates4 #g pp4--,jour4 ,am4 ,chem4  
,soc41        ,vol4 ,,xii1 ,no4 #aj4    
--,a ,theory of the ,mica ,group4 #aj   
pp4--,am4 ,jour4 ,sci41 ,nov4 #ahhi4    
,clarke ,f4 ,w4 7and ,j4 ,s4 ,diller47  
--,topaz from ,stoneham1 ,maine4 #g     

pp4--,am4 ,jour4 ,sci41 ,may1 #ahhh4    
--,turquois from ,new ,mexico4 #g       
pp4--,am4 ,jour4 ,sci41 ,sept41 #ahhf4  
,clarke ,f4 ,w4 7and ,charles ,catlett47
    --,a ,platiniferous ,nickel ,ore    
from ,canada4 #c pp4--,am4 ,jour4 ,sci41
        ,may1 #ahhi4  ,clarke ,f4 ,w4   
7and ,e4 ,a4 ,schneider47    --,on the  
,constitution of ,certain ,micas1       
,vermiculites and ,chlorites4        #aj
 pp4--,am4 ,jour4 ,sci41 ,sept41 #ahia4 
,cohen1 ,e4    --,ueber einige          
eigenthmliche ,melaphyr-,mandelsteine   
aus ,sd-,afrika4        #ae pp4 ,map1 #a
 pl4--,aus dem ,neuen ,jahrb4 ,min41    
#ahge4 ,mandelsteine        ,aus ,den   
,maluti-,bergen1 ,sd-,africa1 #a p4     
,ibid41 #ahhj1 ,bd4 ,i4    --,ueber     
,laven von ,hawaii und einigen anderen  
,inseln des ,grossen        ,oceans     
nebst einigen ,bemerkungen ueber glasige
 ,gesteine im        allgemeinen4 #cj   
pp4--,aus dem ,neuen ,jahrb4 ,min4      
,geol4 und ,pal4        #ahhj1 ,bd4     
,,ii4    --,goldfhrende ,conglomerate in

 ,sd-,afrika4 #c pp4--,mit4 des naturw4 
,vereins fr ,neu-,vorpommern und        
,ruegen1 #ahhg4    --,ueber die         
,trennung von ,thonerde1 ,eisenoxyd und 
,titansure4 #b        pp4--,aus ,neuem  
,jahrb4 fr ,min4 #ahhd4    --,chemische 
,untersuchung des ,meteoreisens von ,s4 
,juliao de ,moreira1        ,portugal1  
sowie einiger anderen hexadrischen      
,eisen4 #ab pp4--,aus        dem ,neuen 
,jahrbuch fr ,mineralogie1 #ahhi1 ,bd4  
,i4    --,zusammenstellung              
petrographischer ,untersuchungsmethoden 
nebst        ,angabe der ,literatur4 #cf
 pp4--,aus den ,mit4 aus dem naturw4    
,verein fr ,neu-,vorpommern und ,ruegen 
in ,greifswald4    --,ueber die         
,entstehung des ,seifengoldes4 #bj      
pp4--,mit4 des naturw4        ,vereins  
fr ,neu-,vorpommern und ,ruegen1 #ahhg4 
--,geonostisch-petrographische ,skizzen 
aus ,sd-,afrika4 #dh pp4 #a             
pl4--,aus dem ,neuen ,jahrbuch1 ,min4   
#ahgd4    --,ueber einige               
,vogesengesteine4 #f pp4--,aus dem      

,neuen ,jahrb4 ,min4        ,geol4 und  
,pal41 #ahhc1 ,bd4 ,i4                  
--,andalusitfhrende ,granite4 #c        
pp4--,aus dem ,neuen ,jahrb4 ,min4      
#ahhg1        ,bd4 ,,ii4    --,nekrolog 
von ,jonas ,gustaf ,oscar ,linnarsson4  
#b pp4--,aus dem ,neuen        ,jahrb4  
,min4 #ahhb4 ,bd4 ,i4    --,versammlung 
des ,oberrhein1 geologischen ,vereins zu
 ,duerkheim1        bayr4 ,rheinpfalz1  
am #ac1 #ad und #ae ,april1 #ahhb4      
,ueber einen        ,aventurinquartz aus
 ,ostindien4    --,berichtigung bezglich
 des ,olivin-,diallag-,gesteins von     
,schriesheim im ,odenwald4 #b pp4--,aus 
dem ,neuen ,jahrb4 ,min4 #ahhe1         
,bd4 ,i4    --,ueber ,pleochroitische   
,hfe in ,biotit4 #e pp4--,aus den ,neuen
 ,jahrb4        ,min4 #ahhh1 ,bd4 ,i4   
--,kersantit von ,laveline4 #b pp4--,aus
 den ,neuen ,jahrb4 ,min4 #ahgi4        
--,das ,labradoritfhrende ,gestein der  
,kste von ,labrador4 #c pp4--,aus       
den ,neuen ,jahrb4 ,min4 #ahhe1 ,bd4 ,i4
    --,ueber eine verbesserte ,methode  

der ,isolirung von                      
,gesteinsgemengtheilen vermittelst      
,flussure4 #c pp4--,mit4 des            
naturw4 ,vereines fr ,neu-,vorpommern   
und ,ruegen1 #ahhh4    --,die ,gold     
production ,transvaal in ,jahre #ahhi4  
--,ueber eine ,pseudomorphose nach      
,markasit aus der ,kreide von ,arcona   
auf ,ruegen4 #d pp4--,aus den           
,sitzungsberichten des naturw4 ,vereins 
fr ,neu-,vorpommern und ,ruegen1 #ahhf4 
--,das ,obere ,weilerthal und das       
,zunchst ,angrenzende ,gebirge4         
#aej pp4--,abhandlungen zur             
,geologischen ,speciakarte von          
,elsass--,lothringen4    --,ueber den   
,granat der sd-afrikanischen            
,diamantfelder und ueber den            
,chromgehalt der ,pyrope4 #d pp4--,aus  
der ,mit4 des naturw4 ,vereins        fr
 ,neu-,vorpommern und ,ruegen1 #ahhh4   
--,ueber ,speckstein1 ,pseudophit und   
dichten ,muscovit aus ,sd-,afrika4 #f   
pp4--,aus dem ,neuen ,jahrb4 ,min4      
#ahhg1 ,bd4 ,i4    --,titaneisen von den

 ,diamantfeldern in ,sd-,afrika4 #b     
pp4--,aus dem        ,neuen ,jahrb4     
,min4 #ahgg4    --,ueber den ,meteoriten
 von ,zsadany1 ,temesvar ,comitat1      
,banat4 #aj        pp4--,aus den        
,verhandlungen des ,naturhist-,med4     
,vereins zu        ,heidelberg4 ,,ii    
,bd41 #b ,heft4  ,cohen ,e4 und ,w4     
,deecke4    --,ueber ,geschiebe aus     
,neu-,vorpommern und ,ruegen4 #hd       
pp4--,aus den        ,mitt4 des         
naturwiss4 ,vereines fr ,neu-,vorpommern
 und ,ruegen1        #ahha4    --,sind  
die ,stoerungen in der ,lagerung der    
,kreide an de ,ostkste von              
,jasmund 7,ruegen7 durch ,faltungen zu  
erklren8 #aj pp4 #c pl4--,aus        den
 ,mit4 des naturwiss4 ,vereins fr       
,neu-,vorpommern und ,ruegen1           
#ahhi4    --,ueber das ,krystalline     
,grundgebirge der ,inseln ,bornholm4    
,cohen ,e4 und ,e4 ,weinschenk4         
--,meteoreisen-,studien4 #cb            
pp4--,annalen des ,k4 ,k4               
,naturhistorischen        ,hofmuseums4  

,bd4 ,,vi4 ,heft #b1 #ahia4  ,cross1    
,whitman4    --,the ,post-,laramie ,beds
 of ,middle ,park1 ,colo4 #bg           
pp4--,proc4 ,colo4        ,sci4 ,soc41  
,oct4 #c1 #ahib4    --,post-,laramie    
,deposits of ,colorado4 #bb pp4--,am4   
,jour4 ,sci41 ,july1        #ahib4      
7and ,l4 ,g4 ,eakins74    --,a ,new     
,occurrence of ,ptilolite4--,am4 ,jour4 
,sci41 ,aug41 #ahib4  ,crosskey1 ,h4 ,w4
    --,on a section of ,glacial drift   
recently explored in ,icknield ,street1 
,birmingham4 #h pp41 #c pl4--,proc4     
,birm4 ,phil4 ,soc4 ,vol4 ,,iii1 p4     
#bji4    --,notes on some of the        
,glacial ,phenomena of the ,vosges      
,mountain1 with        an account of the
 ,glacier of ,kertoff4 #ab pp4--,jan4   
#i1 #ahgi4    --,recent ,researches into
 the ,post-,tertiary ,geology of        
,scotland4 #ab        pp4--,phil4 ,soc41
 ,glasgow1 ,dec4 #g1 #ahfh4    --,on the
 ,tellino ,calcarea ,bed at ,chappel    
,hall1 near ,airdrie4    --,some        
additions to the ,fauna of the          

,bridlington 7post-,tertiary7 ,bed4     
#f pp4--,proc4 ,birmingham ,phil4 ,soc4 
,vol4 ,,ii1 part ,,ii1 ,june #i1        
#ahia4    --,report of the ,committee of
 the ,b4 ,a4 ,a4 ,s4 appointed for the  
purpose of recording the position1      
height above sea-level1                 
character1 etc4 of ,erratic blocks of   
,eng4 ,wales and ,ire4--,brit4          
,assoc4 #ahgc1 #ahgh1 #ahhb1 #ahhc1     
#ahhd1 #ahhe1 #ahhf1 #ahhg1 #ahhh1      
#ahia4    7and ,david ,robertson74      
--,the ,post-tertiary ,fossiliferous    
,beds of ,scotland4 #af pp41 #a         
pl4--,trans4 ,geol4 ,soc4 ,glasgow1     
,vol4 ,,iv1 ,part ,,iii1 page #bda4 #h  
pp41 ,vol4 ,v41 ,part ,i1 page #bi4     
,davis ,w4 ,m4    --,the ,convex        
,profile of ,bad ,land ,divides4--,sci41
 ,oct4 #bh1 #ahib4    --,the ,deflective
 ,effect of the ,earth's ,rotation4 #h  
pp4--,am4 ,met4        ,jour41 ,april1  
#ahhe4    --,the ,subglacial ,origin of 
,certain ,eskers4 #bc pp4--,proc4       
,boston ,soc'y        of ,nat4 ,hist4   

,vol4 ,,xxi1 ,may1 #ahib4    --,outline 
of a ,course in ,elementary ,descriptive
 and ,physical        ,geography for    
,grades ,,iv4 and ,v4 in the ,cambridge 
,grammar ,school1        #ahib-c4 #d pp4
    --,outline of ,elementary           
,meteorology4 ,a synopsis of course     
,geology ,i        at ,harvard ,college1
 #ahib-c4  ,dawson1 ,geo4 ,m4,d41 ,d4   
,sc41 ,f4,g4,s4    --,recent            
observations in the ,glaciation of ,br4 
,columbia and ,adjacent        ,regions4
 #d pp41 #a pl4--,geol4 ,mag41 ,aug41   
#ahhh4  ,dawson1 ,sir ,wm4 ,j4    --,the
 ,geological ,history of ,plants4 #b    
pp4--,botanical ,gazette1 ,vol4         
,,xiii41 ,no4 #f4  ,deeche1 ,w4         
--,der ,monte ,vulture in der           
,basilicata 7,unteritalien7 #gh pp4 #a  
,map41 #a        pl4--,aus dem ,neuen   
,jahrb4 ,min4 ,geol4 und ,pal4          
,beilageband ,,vii4  ,dewey1 ,frederic  
,p4    --,a ,preliminary ,catalogue of  
the ,systematic ,collection in ,economic
        ,geology and ,metallurgy in the 

,u4 ,s4 ,national ,museum4 #bef         
pp4--,bull4 ,u4 ,s4 ,nat4 ,mus4 ,no4    
#db4    --,plan to ,illustrate          
,resources of the ,u4 ,s4 and their     
,utilizations1        at the ,world's   
,industrial and ,cotton ,centennial     
,exposition        of #ahhd-he at ,new  
,orleans4 #h pp4 ,proc4 ,u4 ,s4 ,nat4   
,mus4 #ahhd1        ,appendix4          
--,photographing the ,interior of a     
,coal ,mine4 #h pp41 #d pl4--,am4 ,inst4
        ,min4 ,eng41 ,july1 #ahhg4      
--,some ,canadian ,iron ,ores4 #ab      
pp4--,trans4 ,am4 ,inst4 ,min4 ,eng41   
,vol4        ,,xii4 #ahhd4    --,report 
of the ,department of ,metallurgy in the
 ,u4 ,s4 ,national        ,museum4 #d   
pp4--,report to the ,nat4 ,mus41        
#ahhh-hi4    --,the ,department of      
,metallurgy and ,economic ,geology in   
the ,u4 ,s4 ,nat4        ,mus4 #bf      
pp4--,am4 ,inst4 ,min4 ,eng41 ,sept41   
#ahij4    --,hampe's ,method of         
,determination ,cu#b,o in ,metallic     
,copper4 #f        pp4--,proc4 ,u4 ,s4  

,nat4 ,mus41 #ahhh4    --,porosity of   
,specific ,gravity of ,coke4 #af        
pp4--,trans4 ,am4 ,inst4 ,min4          
,eng41 ,june1 #ahhh4    --,the ,lewis   
and ,bartlett ,bag-,process of          
collecting ,lead ,fumes at the          
,lone ,elm ,works1 ,joplin1 ,mo4 #cb    
pp41 ,ill4--,am4 ,inst4 ,min4 ,eng41    
,feb41 #ahij4    --,note on the         
,nickel-,ore of ,russell ,springs1      
,logan ,co41 ,kan4--,am4        ,inst4  
,min4 ,eng4    --,note on the ,falling  
,cliff ,zinc ,mine4 #b pp4--,am4 ,inst4 
,min4 ,eng41        ,may1 #ahia4        
--,the ,heroult ,process of ,smelting   
,aluminum ,alloys4 #h pp4--,am4 ,inst4  
,min4 ,engin41 ,feb41 #ahij4    --,pig  
,iron of ,unusual ,strength4 #ah        
pp4--,am4 ,inst4 ,min4 ,eng41 ,oct41    
#ahhh4  ,diller1 ,j4 ,s4    --,geology  
of the ,taylorville ,region of          
,california4 #be pp41                   
,ill4--,bull4 ,geol4 ,soc4 ,am41 ,vol4  
#c4 pp4 #cfi-cid4    --,peridotite of   
,elliott ,county1 ,kentucky4 #cb pp41   

,ill4--,bull4 ,u4 ,s4        ,g4 ,s41   
,no4 #ch4    --,notes on the ,geology of
 ,northern ,cal4 #bbd pp4--,bull4 ,u4   
,s4 ,g4 ,s41        ,no4 #cc4           
--,fulgurite from ,mt4 ,thielson1       
,oregon4 #g pp41 ,ill4--,am4 ,jour4     
,sci41        ,oct41 #ahhd4    --,notes 
on the ,peridotite of ,elliot ,county1  
,ky4 #e pp4--,am4 ,jour4        ,sci41  
,aug41 #ahhf4    --,a ,late ,volcanic   
,eruption in ,northern ,cal4 and its    
,peculiar ,lava4        #cc pp41 ,,xvii 
pl41 #d cuts4--,bull4 ,u4 ,s4 ,g4 ,s41  
#gi1 #ahia4  ,emmons1 ,s4 ,f4           
--,abstract of a ,report upon the       
,geology and ,mining ,industry of       
,leadville1 ,colorado4 #ij pp41 with    
maps4--,ann4 ,rep4 ,u4 ,s4 ,g4 ,s41     
#ahhj-ha4    --,orographic ,movements in
 the ,rocky ,mountains4 #bb pp4--,bull4 
,geol4        ,soc'y ,am41 ,vol4 ,i41 pp
 #bde-hf4    --,notes on the ,geology of
 ,butte1 ,montana4 #ad pp4--,trans4 ,am4
 ,inst4        ,min4 ,eng41 ,july1      
#ahhg4    --,the ,genesis of ,certain   

,ore ,deposits4 #bb pp4--,trans4 ,am4   
,inst4 ,min4        ,eng41 ,march1      
#ahhf4    --,structural ,relations of   
,ore ,deposits4 #cf pp4--,am4 ,inst4    
,min4 ,eng41        ,feb41 #ahhh4       
--,notes on the ,gold ,deposits of      
,montgomery ,county1 ,maryland4 #bb     
pp4--,am4 ,inst4 ,min4 ,eng41 ,feb41    
#ahij4    --,on ,glaciers in the ,rocky 
,mountains4 #af pp4--,proc4 ,col4 ,sci4 
,soc'y1        #ahhg4    --,preliminary 
,notes on ,aspen1 ,col4 #bf pp4--,proc4 
,col4 ,sci4 ,soc'y1        #ahhg4       
--,fluor-,spar ,deposits of ,southern   
,ill4 #bd pp1 map4--,am4 ,inst4 ,min4   
,eng41 ,baltimore ,meeting1 ,feb41      
#ahib4    --,the ,mining ,work of the   
,u4 ,s4 ,geol4 ,survey4 #ac pp4--,trans4
 ,am4 ,inst4        ,min4 ,eng41        
,washington ,meeting1 ,feb41 #ahib4     
--,on the ,origin of ,fissure ,veins4   
#bj pp4--,proc4 ,col4 ,sci4 ,soc'y1     
#ahhg4  ,emmons1 ,s4 ,f4 7and ,g4 ,e4   
,becker74    --,geological ,sketches of 
the ,precious ,metal ,deposits of the   

,western        ,united ,states1 with   
notes on ,lead ,smelting at ,leadville4 
#bif        pp4--,tenth ,census ,u4 ,s41
 ,vol4 ,,xiii ,statistics and           
,technology of        the ,precious     
,metals4  ,emerson1 ,george ,h4         
--,observations on ,crystals and        
,precipitations in ,blowpipe ,beads4 #ah
        pp41 ,ill4--,proc4 ,am4 ,acad4  
of ,arts and ,sci41 ,march1 #ahfe4      
,fisher1 ,rev4 ,o4    --,mr4 ,mallet's  
,theory of ,volcanic ,energy ,tested4   
#ah pp4--,phil4 ,mag41        ,oct41    
#ahge4    --,review of ,captain         
,dutton's ,critical ,observations on    
,theories of the        ,earth's        
,physical ,evolution4 #h pp4--,geol4    
,mag41 ,aug41 #ahgf4    --,on the       
,possibility of ,changes in the         
,latitude of places on the              
,earth's ,surface4 ,being an appeal to  
,physicists4 #g pp4--,geol4             
,mag41 ,july1 #ahgh4    --,on ,theories 
to ,account for ,glacial ,submergence4  
#h pp4--,phil4 ,mag41        ,oct41     

#ahib4    --,on ,dynamo ,metamorphism4  
#b pp4--,geol4 ,mag41 ,july1 #ahij4     
--,on the ,warp1 its ,age and ,probable 
,connection with the last               
,geological ,events4 #ab pp41           
,ill4--,quart4 ,jour4 ,geol4 ,soc'y1    
,nov41        #ahff4    --,on           
,implement-bearing ,loams in ,suffolk4  
#e pp4--,proc4 ,cambridge ,phil4        
,soc'y1 ,vol4 ,,iii1 ,pt4 ,,vii4        
--,on the ,brocklesham ,beds of the     
,isle of ,wight ,basin4 #cj pp4--,proc4 
,geol4 ,soc'y1 ,may1 #ahfb4    --,on a  
,mammaliferous ,deposit at ,barrington1 
near ,cambridge4 #aa pp41               
,ill4--,quart4 ,journ4 ,geol4 ,soc'y1   
,nov41 #ahgi4    --,on the ,denudation  
of ,soft ,strata4 #d pp4--,quart4       
,journ4 ,geol4 ,soc'y1        ,feb41    
#ahfa4    --,on the ,occurrence of      
,elephas ,meridonalis at ,dervlish1     
,dorset4 #h        pp41 ,ill4--,quart4  
,journ4 ,geol4 ,soc'y1 ,nov41 #ahhh4    
--,glacial ,action and ,raised          
,sea-,beds4 #d pp41 ,ill4--,geol4 ,mag41

 ,april1        #ahgc4    --,on the     
,origin of the ,estuary of the ,fleet in
 ,dorsetshire4    --,on the ,brick-pit  
at ,lexden1 near ,colchester 7with notes
 on the        ,coleoptera1 by ,t4 ,u4  
,wollaston74 #i pp41 ,ill4--,quart4     
,journ4        ,geol4 ,soc'y of ,london1
 #ahfc4    --,on ,faulting1 ,jointing   
and ,cleavage4 #gb pp41 ,ill4--,geol4   
,mag41 ,may1        #ahhd4    --,remarks
 upon ,mr4 ,mallet's ,strictures on the 
,mathematical ,test        applied to   
his ,theory of ,volcanic ,energy1 by    
,mr4 ,o4 ,fisher4 #f        pp4--,phil4 
,mag41 ,feb41 #ahgf4    --,on the       
,phosphatic ,nodules of the ,cretaceous 
,rock of ,cambridgeshire4        #ad    
pp41 #a pl4--,quart4 ,journ4 ,geol4     
,soc'y1 ,feb41 #ahgc4    --,on ,faults4 
,reply to ,professor ,blake's           
,criticisms4 #c pp4--,geol4             
,mag41 ,sept41 #ahhd4    --,uniformity  
and ,vulcanicity4 #c pp4--,geol4 ,mag41 
,march1 #ahge4    --,the ,cause of      
,slaty ,cleavage4 #d pp4--,geol4 ,mag41 

,april1 #ahhe4    --,on the ,thermal    
,conditions and on the ,stratification  
of the        ,antarctic ,ice4 #ac      
pp4--,phil4 ,mag41 ,june1 #ahgi4        
--,on ,cleavage and ,distortion4 #aa    
pp4--,geol4 ,mag41 ,sep41 #ahhd4        
--,on the ,ages of the ,trail and ,warp4
 #g pp4--,geol4 ,mag41 ,may1 #ahfg4     
--,review of ,dutton's ,grand ,caon1    
,colorado4 #d pp4--,geol4 ,mag41 ,july1 
#ahhc4    --,on the ,theory of the      
,erosion of ,lake ,basins by ,glaciers4 
#b        pp4--,geol4 ,mag41 ,june1     
#ahgf4    --,oblique and ,orthogonal    
,sections of a ,folded ,plane4 #d pp41  
,ill4--,geol4 ,mag41 ,jan41 #ahia4      
--,on the ,cromer ,cliffs4 #d pp41      
,ill4--,geol4 ,mag41 ,april1 #ahhj4     
--,on ,some ,natural ,pits on the       
,heaths of ,dorsetshire4 #b pp4--,quart4
        ,journ4 ,geol4 ,soc'y1 ,london1 
#aheh4    --,on ,cirques and ,toluses4  
#d pp4--,geol4 ,mag41 ,jan41 #ahgb4     
--,on a ,worked ,flint from the         
,buck-,earth of ,crayford1 ,kent4 #b    

pp4--,geol4 ,mag41 ,june1 #ahgb4        
,frazer1 ,dr4 ,persifor4    --,general  
,notes on the ,new ,orleans ,industrial 
and ,cotton ,exhibition4        #bj     
pp4--,journal ,franklin ,institution1   
,june1 #ahhe4    --,the ,eozoic and     
,lower ,paleozoic in ,south ,wales and  
their ,comparison        with their     
,appalachian ,analogues4 #ah pp4--,am4  
,inst4 ,min4 ,engin41        ,feb41     
#ahhc4    --,geological and ,mineral    
,studies in ,nuevo ,leon and ,coahuilla1
 ,mexico4        #cf pp41 ,,iii1 and    
maps4--,am4 ,inst4 ,min4 ,engin41 ,feb41
 #ahhd4    --,trap ,dykes in the        
,archaean ,rocks of ,southeastern       
,pennsylvania4 #d        pp4--,am4      
,phil4 ,soc41 ,oct4 #ag1 #ahhd4         
--,classification of ,coals4 #bb        
pp4--,trans4 ,am4 ,inst4 ,min4 ,engin41 
,vol4        ,,vi1 #ahgi4               
--,descriptive ,table of ,elements4 #b  
pp4--#ahia4    --,the late              
,international ,geological ,congress at 
,berlin4 #d pp4--,am4        ,phil4     

,soc'y1 ,nov4 #bj1 #ahhe4    --,report  
of the ,american ,committee of the      
,international ,congress of             
,geologists4 #e pp4--,proc4 ,a4 ,a4 ,a4 
,s41 ,vol4 ,,xxxv1 ,august1 #ahhf4      
--,general ,notes on the ,geology of    
,york ,county1 ,penn4 #bj pp4--,colored 
maps4    --,on the ,physical and        
,chemical ,characteristics of a ,trap   
occurring at        ,williamson's       
,point1 ,penn4 #h pp41 #a colored plate4
 ,read before        ,am4 ,phil4 ,soc'y1
 ,dec4 #bj1 #ahgh4    --,an ,hypothesis 
of the ,structure of the ,copper ,belt  
of the ,south        ,mountain4 #d pp41 
,ill4--,trans4 ,am4 ,inst4 ,min4        
,engin41 ,june1 #ahhc4        ,read at  
the ,roanoke1 ,va41 ,meeting4    --,a   
,broader ,field for the ,u4 ,s4         
,geological ,survey4 #d pp4--,journ4    
,franklin ,instit41 ,sept41 #ahhh4      
--,the ,peach ,bottom ,slates of the    
,lower ,susquehanna1 with sections of   
the ,right and ,left ,banks4 #e pp41 #c 
pl4--,am4 ,inst4 ,min4 ,eng41           

,oct41 #ahhc4    --,reply to a paper    
entitled ,notes on the ,geology of      
,chester ,valley        and ,vicinity4  
#h pp4--,journ4 ,franklin ,inst41       
,april1 #ahhd4    --,mr4 ,theodore ,d4  
,rand's ,criticism of ,vol4 ,c#d        
,geology of ,chester        ,county1    
,penn4 #f pp4--,journ4 ,franklin ,inst41
 ,oct41 #ahhc4    --,archaean           
,characters of the ,rocks of the        
,nucleal ,ranges of the                 
,antilles4 #a p4--,brit4 ,assn41 #ahhh4 
--,notes on ,fresh-,water ,wells of the 
,atlantic ,beach4 #d pp4--,journ4       
,franklin ,inst41 ,sept41 #ahij4        
--,the ,position of the ,american ,new  
,red ,sandstone4 #h pp4--,trans4 ,am4   
,inst4 ,min4 ,engin41 ,vol4 ,v4    --,on
 the ,traps of the ,mesozoic ,sandstone 
in ,york and ,adams ,counties1          
,penn4 #ac pp41 #d pl4--,am4 ,phil4     
,soc'y1 ,april #af1 #ahge4    --,the    
,whopper ,lode1 ,gunnison ,county1      
,colo4 #aj pp4--,am4 ,inst4 ,min4       
,engin41 ,aug41 #ahhj4    --,some       

,copper ,deposits of ,carroll ,county1  
,md4 #h pp41 #a pl4--,am4 ,inst4        
,min4 ,engin41 ,aug41 #ahhj4    --,a    
,convenient ,device to be ,applied to   
the ,hand ,compass4 #a p4--,am4         
,phil4 ,soc'y1 ,dec4 #e1 #ahhd4         
--,the ,approaches to a ,theory of the  
,causes of ,magnetic ,declination4      
#af pp4--,am4 ,phil4 ,soc'y1 ,apr4 #f1  
#ahgg4    --,on ,improvement in the     
,construction of the ,hypsometric       
,aneroid4--,am4        ,phil4 ,soc'y1   
,march #b1 #ahhc4    --,an ,exfoliation 
of ,rocks near ,gettysburg4 #b pp4--,am4
 ,phil4 ,soc'y1        ,dec4 #d1 #ahgd4 
--,note on the ,new ,geological ,map of 
,europe4 #f pp4--,trans4 ,am4 ,inst4    
,min4 ,engin4    --,some ,supposed      
,fossils from the ,susquehanna ,river1  
just ,south of the                      
,pennsylvania-,maryland ,line4 #c pp41  
#a pl4--,proc4 ,am4 ,phil4 ,soc'y       
,,xviii1 ,sept4 #ah1 #ahgi4             
--,missing ,ores of ,iron4 #ab pp41     
,ill4--,trans4 ,am4 ,inst4 ,min4        

,engin41        ,vol4 ,,vi1 #ahgi4      
--,the ,peach ,bottom ,slates of        
,southeastern ,york and ,southern       
,lancaster        ,counties1 ,penn4 #e  
pp41 #a4 pl4--,trans4 ,am4 ,inst4       
,mining ,engin41        #ahhc4    --,a  
,speculation on ,protoplasm4 #g pp4--,am
 ,nat41 ,july1 #ahgf4    --,a ,mirror   
for ,illuminating ,opaque ,objects for  
the ,projecting        ,microscope4 #b  
pp4--,am4 ,phil4 ,soc'y1 ,feb4 #bj1     
#ahhj4    --,the ,progress of ,chemical 
,theory2 ,its ,helps and ,hindrances4   
#cg        pp4--,journ4 ,franklin       
,instit41 ,apr41 ,may and ,june1 #ahia4 
--,mineral ,formul4 #f pp4--,proc4      
,acad4 ,nat4 ,sci41 ,phila41 ,july #g1  
#ahgd4    --,notes from the ,literature 
on the ,geology of ,egypt1 and          
,examination        of the ,syenitic    
,granite of the ,obelisk which ,lieut4  
,comd'r        ,gorringe1 ,u4 ,s4 ,n41  
brought to ,new ,york4 #bg pp41 #d      
pl4--,trans4        ,am4 ,inst4 ,mining 
,engin41 #ahhc4    --,report of         

,committee on the ,international        
,congress of ,geologists4 #c            
pp4--,proc4 ,a4 ,a4 ,a4 ,s41 ,vol4      
,,xxxix1 #ahij4    --,on ,certain ,trap 
,rocks from ,brazil4 #c pp4--,proc4     
,acad4 ,sci41 ,phila41        #ahgf4    
--,an ,unjust ,attack4 #h pp4--,am4     
,geol41 ,jan41 #ahhi4    --,the         
,philadelphia ,meeting of the           
,international ,congress of             
,geologists4 #aj pp41 ,am4 ,geol41      
,june1 #ahij4    --,report of the       
,berlin ,international ,geological      
,congress4 #ac pp4--,am4        ,jour4  
,sci41 ,,xxx1 ,december1 #ahhe4         
--,mesozoic ,sandstone of the ,atlantic 
,slope4 #i pp4--,am4 ,nat41 ,may1       
#ahgi4    --,archan-,paleozoic ,contact 
near ,philadelphia1 ,penn4 #f pp41 #a   
pl4--,proc4 ,a4 ,a4 ,a4 ,s41 ,vol4      
,,xxxiii1 ,sept41 #ahhd4    --,report of
 the ,sub-,committee of the ,berlin     
,congress of ,geologists on        the  
,archan4 #hj pp4    --,crystallization4 
#aa pp41 ,ill4--,journal ,franklin      

,inst41 ,aug41 #ahhe4    --,origin of   
the ,lower ,silurian ,limonites of ,york
 and ,adams ,counties1        #f        
pp4--,am4 ,phil4 ,soc'y1 ,march #ai1    
#ahge4    --,the ,northern ,serpentine  
,belt in ,chester ,county1 ,pa4 #h      
pp4--,trans4        ,am4 ,inst4 ,min4   
,engin41 #ahhc4    --,the ,persistence  
of ,plant and ,animal ,life under       
,changing ,conditions        of         
,environment4 #ac pp4--,am4 ,nat41      
,june1 #ahij4    --,international       
,congress of ,geologists1 #ahhf4 #aji   
pp41 #a pl4    --,international         
,congress of ,geologists1 ,reports of   
the ,sub-,committee        appointed by 
the ,american ,committee4 #bci pp41     
#ahhh4    --,other ,short ,articles4    
,frisbie1 ,dr4 ,j4 ,f4    --,glacial    
,moraines4 #af pp4    --,mountain       
,building and ,mountain ,sculpture4 #ac 
pp4    --,the ,franconia ,flume1 the    
,causes that led to its ,formation4 #h  
pp4    --,planet ,building4 #aa pp41 #a 
pl4    --               #ag pp41 #b pl4 

,geikie1 ,sir ,archibald1 ,,ll4,d41     
,d4,sc1 ,f4,r4,s4,e41 ,p4,g4,s4         
--,address to the ,geological ,section  
of the ,british ,association4 #bc pp4   
--,address by ,sir ,archibald ,geikie1  
,president of ,british ,association     
for the ,advancement of ,science4 #ahib4
 #bd pp4    --,progress of the          
,geological ,survey in ,scotland4 #aj   
pp4--,proc4 ,royal        ,soc'y1       
,edinburgh1 ,vol4 ,,ii1 ,session        
#ahfd-e4    --,on the ,tertiary         
,volcanic ,rocks of the ,british        
,islands4 #d pp4--,proc4        ,royal  
,soc'y1 ,edinburgh1 #ahff-fg4    --,the 
,history of ,volcanic ,action during the
 ,tertiary ,period in the               
,british ,islands 7,abstract74 #e       
pp4--,proc4 ,royal ,soc'y1 ,edin41      
#ahhh4    --,address delivered at the   
#cfth ,anniversary ,meeting of the      
,edinburgh        ,geological ,society4 
,also ,notes for a ,comparison of the   
,volcanic        ,geology of ,central   
,scotland with that of ,auvergne and the

 ,eifel4        #af pp4--,trans4 of the 
,edinburgh ,geological ,society1        
#ahfi-gj1        ,vol4 ,,ii1 ,part ,i4  
--,on ,modern ,denudation4 #ch          
pp4--,trans4 ,geol4 ,soc'y of ,glasgow1 
,vol4        ,,iii1 p4 #aec4    --,on   
,denudation now in ,progress4 #f        
pp4--,geol4 ,mag41 ,vol4 ,i1 ,no4 #f1   
,june1 #ahfh4    --,earth ,sculpture and
 the ,huttonian ,school of ,geology4    
,the ,inaugural        ,address         
,delivered at the #djth ,anniversary    
,meeting of the        ,edinburgh       
,geological ,society1 ,nov4 #f1 #ahgc4  
--,recent ,researches into the ,origin  
and ,age of the ,highlands of           
,scotland and the ,west of ,ireland4 #ai
 pp4    --,royal ,institute of ,great   
,britain1 #ahhi4    --,the ,caons of the
 ,far ,west4--,ibid41 ,april #f1 #ahhc4 
#d pp4    --,rock-,weathering1 as       
illustrated in ,edinburgh ,churchyards4 
#ae pp41 #a        pl4--,proc4 ,royal   
,soc'y1 ,edinburgh1 ,vol4 ,x41 ,april   
#ai1 #ahhj4    --,the ,ancient ,glaciers

 of the ,rocky ,mountains4 #g pp4--,am4 
,nat4 ,jan4        #ahha4    --,the ,ice
 ,age in ,britain4--,science ,lectures  
for the ,people4 #ag pp4    --,the ,old 
,man of ,hoy4 #f pp41 #a pl4--,report   
,brit4 ,assoc41 #ahga4    --,on the ,old
 ,red ,sandstone of the ,south of       
,scotland4 #ab pp41 #a                  
pl4--,quarterly ,journal ,geol4 ,soc'y1 
,aug4 #ahfj4    --,on the ,geology of   
,strath1 ,skye1 7with descriptions of   
some ,fossils        from ,skye1 by ,t4 
,wright1 ,m4,d41 ,f4,r4,s4,e47 #cf pp41 
#a pl4    --,the ,history of ,volcanic  
,action in the ,area of the ,british    
,isles4        #aai pp4--,quarterly     
,journal of the ,geological ,society of 
,london1        ,vol4 ,,xlviii1 #ahib4  
--,on the ,supposed ,pre-,cambrian      
,rocks of ,st4 ,david's4 #ff pp41 #c    
pl4--,quarterly ,journal of the         
,geological ,society1 ,aug4 #ahhc4      
--,on the ,tertiary ,volcanic ,rocks of 
the ,british ,islands4 #ca pp41 #a pl4  
--,the ,geological ,origin of the       

,present ,scenery of ,scotland4 #ba pp4 
,ill4--,the ,journal of ,travel and     
,natural ,history4    --,on the ,age of 
the ,altered ,limestone of ,strath1     
,skye4--#ac pp4        ,ill4--,quart4   
,journal ,geol4 ,soc'y1 #ahhh4          
--,address of the ,president of the     
,geological ,society of ,london1 ,feb4  
#bj1 #ahia4 #abf pp4    --,the ,origin  
of ,coral ,reefs4 #ac pp4 ,ill4--,proc4 
,royal ,physical ,soc'y4        ,vol4   
,,viii1 p42 #ahhd4    --,the ,pitchstone
 of ,eskdale1 a retrospect and          
comparison of        ,geological        
,methods4 ,ibid1 ,vol ,v1 #ahhj4        
,genth1 ,f4 ,a4    --,ueber             
,nordamerikanische ,tellur-und          
,wismuth-,mineralien4 #ad               
pp4--,journal fr ,praktische ,chemie1   
#ahgd4    --,ueber ,lansfordit1         
,nesquehonit und ,pseudomorphosen von   
,nesquehonit        nach ,lansfordit4   
7,f4 ,a4 ,genth und ,s4 ,l4 ,penfield74 
#ah pp41 #a        pl4--,zeit4 fr       
,krystallographie1 #ahij4               

--,contributions to ,mineralogy4 #ah    
pp41 #a pl4 ,read before ,am4 ,phil4    
,soc'y1 ,oct4 #b1 #ahhe4    --do4 #ba   
pp4 ,read before ,am4 ,phil4 ,soc'y1    
,march #ah1 #ahhg4    --,investigation  
of ,iron ,ores and ,limestones from     
,blair and ,huntingdon        counties1 
,pa4 #bf pp4--,read before the ,am4     
,phil4 ,soc'y1 ,feb4 #f1        #ahgd4  
--,contributions to ,mineralogy4 #f     
pp4--,am4 ,jour4 ,sci41 ,sept4 #ahhi2 #d
        pp4 ,jan41 #ahij4    --do4 with 
,crystallographic notes by ,s4 ,l4      
,penfield4 #i pp4--,am4 ,jour4          
,sci41 ,sept41 #ahij2 #aj pp4 ,may1     
#ahia3 #f pp4 ,march1 #ahib4    --,on   
,american ,tellurium and ,bismuth       
,minerals4 #i pp4--,am4 ,phil4 ,soc'y1  
,aug4 #ba1 #ahgd4    --,on ,herderite4  
#g pp4 ,read before ,am4 ,phil4 ,soc'y1 
,oct4 #ag1 #ahhd4    --,on ,lansfordite1
 ,nesquehonite1 a ,new ,mineral and     
,pseudomorphs of        ,nesquehonite   
after ,lansfordite4 #ag pp41 #a         
pl4--,am4 ,jour4 ,sci41        ,feb41   

#ahij4    --,the ,minerals of ,north    
,carolina4--,bulletin #gd1 ,u4 ,s4 ,g4  
,s4 #abj pp4    --,the ,minerals and    
,mineral ,localities of ,north          
,carolina4 #abb        pp4--,geol4 of   
,north ,carolina1 ,vol4 ,,ii1 #ahha4    
--,first ,annual ,report of ,dr4 ,f4 ,a4
 ,genth1 ,chemist of the ,pennsylvania  
,board of ,agriculture4 #cb pp41 #ahgh4 
--,second ,preliminary ,report on the   
,mineralogy of ,pennsylvania1 with      
,analyses of ,mineral ,spring ,waters4  
#ch pp4    --,ueber einige ,tellur-und  
,vanad-,mineralien4 #ac pp4--,zeit4 fr  
,krystallographie1 etc41 #ahgg4    --,on
 the ,equivalent of ,cerium by the late 
,dr4 ,charles ,wolf4 #aj                
pp4--,am4 ,jour4 ,sci41 ,may1 #ahfh4    
--,contributions to ,mineralogy1 ,no4   
#ed2 7with ,crystallographic ,notes     
by ,s4 ,l4 ,penfield74 #i pp4--,am4     
,jour4 ,sci41 ,nov41 #ahib4    --,on    
,penfieldite1 a new species4 #a         
pp4--,am4 ,jour4 ,sci41 ,sept41 #ahib4  
--,mineralogische ,mittheilungen1 by ,f4

 ,a4 ,genth 7with ,crystallographic     
,notes by ,s4 ,l4 ,penfield74 #aj pp4   
,ill4--,zeit4 fr ,krystallog4           
,,xviii1 #f1 7#ahia74    --,examination 
of the ,north ,carolina ,uranium        
,minerals4 #g pp4--,am4        ,chem4   
,jour4 ,vol4 ,i1 ,nos4 #b and #c4       
--,on some ,american ,vanadium          
,minerals4 #f pp4--,am4 ,jour4 ,sci41   
,july1        #ahgf4    --,on an        
undescribed ,meteoric ,iron from ,east  
,tennessee4 #d pp41 #b                  
pl4--,proc4 ,acad4 ,nat4 ,sci4 ,phila41 
,dec4 #bh1 #ahhf4    --,lansfordit1 ein 
neues ,mineral1 #b pp4    --,on the     
,vanadates and ,iodyrite1 from ,lake    
,valley1 ,sierra ,co41 ,new             
,mexico4 #ac pp4 ,read before ,am4      
,phil4 ,soc'y ,apr4 #ag1 #ahhe4         
--,contributions to ,mineralogy4--,am4  
,jour4 ,sci41 ,sept4 #ahei2 ,march1     
#ahfb1 ,may1 #ahfh4    --,meteorology4  
#f pp4    --,meteorology4 #d pp4--,am4  
,jour4 ,sci41 ,nov41 #ahfa4             
--,re-examination of the ,tetradymite   

from ,field's ,gold ,mine1 ,georgia4    
--,on ,pyrophyllite from ,schuylkill    
,co41 ,penn4 ,read before ,am4 ,phil4   
,soc'y1 ,july #ah1 #ahgh4               
--,mineralogische ,mittheilungen4 #ca   
pp41 #b pl4--,zeit4 fr                  
,krystallographie1 #ahhe4    --,jarosite
 from ,utah4 #a p4--,am4 ,jour4 ,sci41  
,jan41 #ahij4    --,on ,two ,minerals   
from ,delaware ,co41 ,pa4 #c pp4--,proc4
 ,acad4 ,sci4 of        ,phila41 #ahhi4 
--,contributions from the ,laboratory of
 the ,university of ,pennsylvania4      
,gilbert1 ,g4 ,k4    --,the ,colorado   
,plateau ,region considered as a ,field 
for ,geological        ,study4 #bg      
pp4--,am4 ,jour4 ,sci41 ,july and       
,august1 #ahgf4    --,the ,strength of  
the ,earth's ,crust4 #e pp4--,bull4     
,geol4 ,soc4 ,am4 ,vol4        ,i1      
#ahhi4    --,the ,history of the        
,niagara ,river4 #bd pp41 #h pl4--,sixth
 ,an4 ,rept4 of        ,com4 of ,state  
,reservation at ,niagara1 #ahhi4        
--,the ,work of the ,international      

,congress of ,geologists4 #bb pp4--,am4 
,jour4 ,sci41 ,dec1 #ahhg4    --,the    
,sufficiency of ,terrestrial ,rotation  
for the ,deflection of        ,streams4 
#f pp4--,nat4 ,acad4 ,sci41 #ahhd4      
,gordon1 ,c4 ,h4    --,observations on  
the ,keokuk ,species of ,agaricocrinus4 
#g pp41 #a        pl4--,am4 ,geol41     
,may1 #ahij4    --,on the ,brecciated   
,character of the ,st4 ,louis           
,limestone4 #i pp41 #b        pl4--,am4 
,nat41 ,april1 #ahij4    --,proceedings 
of the ,iowa ,academy of ,sciences for  
#ahhg1 #ahhi1 #ahhi4        #aja pp4    
--,quaternary ,geology of ,keokuk1      
,iowa1 with ,notes on the ,underlying   
,rock ,structure4 #h pp41 #b pl4        
,grant1 ,uly4 ,s4    --,notes on the    
,molluscan ,fauna of ,minnesota4 #d     
pp4--#afth ,an4 ,rept4        ,geol4 and
 ,nat4 ,hist4 ,survey1 ,minn4 7#ahhg74  
--,account of a ,deserted ,gorge of the 
,mississippi near ,minnehaha            
,falls4 #f pp41 #a pl4                  
--,conchological ,notes4 #ab pp4--#adth 

,an4 ,rept4 ,geol4 and ,nat4 ,hist4     
,survey1 ,minn4    --,the               
,stratigraphical ,position of the       
,ogishke ,conglomerate of               
,northeastern ,minnesota4 #h pp4--,am4  
,geol4 ,vol4 ,x1 ,july1 #ahib4          
--,report of ,geological ,observations  
made in ,northeastern ,minnesota        
during the ,summer of #ahhh4 #fg        
pp4--,geol4 and ,nat4 ,hist4 ,survey    
of ,minn42 part ,,iv4 #agth ,an4 ,rept4 
,hall1 ,c4 ,w4    --,notes on a         
,geological ,excursion into ,central    
,wisconsin4 #ah pp41 #a        pl4      
,hallock1 ,william4    --,chemical      
,action between ,solids4 #d pp4--,am4   
,jour4 ,sci41 ,may1 #ahhi4    --,the    
,flow of ,solids or the ,behavior of    
,solids under ,high ,pressure4 #h       
pp4--,bull4 ,u4 ,s4 ,g4 ,s41 ,no4 #ee4  
--,ueber die ,lichtgeschwindigkeit in   
verschiedenen ,quartzflchen4 #c         
pp4--,annalen der ,physik und ,chemie1  
#ahha4 ,bd4 ,,xii4    --,preliminary    
,report of ,observations at the ,deep   

,well at ,wheeling1 ,w4                 
,va4--,proc4 ,a4 ,a4 ,a4 ,s41 #ahia1    
vol4 ,,xl4  ,harden1 ,john ,hy41 ,m4 ,e4
    --,rock ,salt ,deposit of ,huron and
 ,bruce ,counties1 ,ontario1 ,canada4 #f
        pp4--,proc4 ,engineer's ,club4  
,phila41 ,vol4 ,i1 ,no4 #c4    --,the   
,construction of ,maps in ,relief4 #bc  
pp41 ,ill41 #a pl4--,trans4 ,am4        
,inst4 ,min4 ,eng41 #ahhg4  ,harpe1     
,phil4 de la4    --,description des     
,nummulites appartenant  la ,zone       
suprieure des        ,falaises de       
,biarritz4 #bj pp41 #a pl4--,bulletin de
 la ,socit de        ,borda1 #ahgi4     
--,une chelle des ,nummulites ou        
,tableau de la distribution             
stratigraphique des ,espces de          
,nummulites4 #e                         
pp4--,verhandlungen de la ,soc4 ,helv4  
des ,sc4 ,nat41 session de        ,st4  
,gall1 #ahgi4    --,note sur les        
,nummulites des ,alpes occidentales4 #f 
pp4--,extrait des        actes de la    
,soc4 ,helv4 des ,sc4 ,nat41 #ahgg4     

--,note sur les ,nummulites des environs
 de ,nice et de ,menton4 #bb pp41       
#a pl4--,bulletin de la ,socit          
,geologique de ,france1 ,octobre1       
#ahgg4    --,ossements appartenant      
,l',anthracotherium ,magnum recueillis  
dans        les ,lignites des environs  
de ,lausanne4 #ad pp4--,bulletin de la  
,soc4 vaud4 des ,sc4 ,nat41 #ahed4      
--,note sur la ,gologie des environs de 
,louche-les-,bains4 #cb pp41 #a         
pl4--,bulletin de la ,soc4 vaud4 des    
,sc4 ,nat41 #ahgg4    --tude sur les    
,nummulites du ,comt de ,nice suivie    
d'une chelle des        ,nummulites ou  
,tableau de la distribution             
stratigraphique des        ,espces de ce
 genre4 #dd pp41 #a pl4--,bulletin de la
 ,soc4 vaud4        des ,sc4 ,nat4      
--,nummulites des ,alpes ,francaises4   
#bf pp4--,bulletin de la ,soc4 vaud4    
,sc4 ,nat4 ,,xvi1 #hb4    --,description
 des ,nummulites des ,falaises de       
,biarritz4 #af pp41 #a                  
pl4--,extrait du ,bulletin de la ,socit 

de ,borda1 #ahha4    --,description des 
,nummulites appartenant  la ,zone       
infrieure des        ,falaises de       
,biarritz des environs de la ,villa     
,bruce jusqu'        ,handia4 #dd       
pp4--,bulletin de la ,socit de ,borda1  
#ahha4    --,description des ,nummulites
 appartenant  la ,zone moyenne des      
,falaises de ,biarritz4 #h pp41         
,ill4--,bulletin de la ,socit de        
,borda1 #ahhj4  ,hayes1 ,c4 ,willard4   
--,the ,overthrust ,faults of the       
,southern ,appalachians4 #ad pp41 #b    
pl4--,bulletin ,geol4 ,soc4 ,am41 ,vol4 
,,ii1 pp4 #ada-aed4    --,report on the 
,geology of ,northeastern ,alabama and  
,adjacent ,portions        of ,georgia  
and ,tennessee4 #hd pp41 #a pl41 #a     
map4--,bulletin ,no4 #d1        ,geol4  
,surv4 of ,alabama4    --,an ,expedition
 through the ,yukon ,district4 #df pp41 
#c maps4--,nat4        ,geog4 ,mag4     
,heyes1 ,j4 ,f41 ,m4,a4    --,aspects of
 ,imperial ,federation4 #h pp4          
--,scientific ,aspects of ,imperial     

,unity4--,european ,mail4    --,the     
,recognition of ,geography4 #g pp4      
7,further acknowledgments of pamphlets  
and of specimens will be made in the    
next issue47          99       99       
99       99       99   ,transcriber     
,note   ,illustrations were moved so as 
to not split paragraphs4 ,minor errors  
were corrected4