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NATORE 
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struct a satisfactory theory of mountain-making, their 
observations of Appalachian structure were of immense 
value in their destructive effect upon some of the notions 
of mountain-making prevalent at the time. 
The true interpretation of the Appalachian waves is 
probably to be found in the contractional theory of moun- 
tain elevation, of which Dana was the leading expounder. 
That the main cause of mountain elevation is tangential 
pressure in the crust resulting from internal contraction 
is now generally acknowledged, though there may be doubt 
whether the main cause of contraction is the cooling of 
the earth from an incandescent condition. 
It is a curious fact that the first published suggestion of 
the agency of ice in connection with the drift came from 
a cotton manufacturer in Connecticut, Peter Dobson by 
name. The credit of the introduction and championship 
of the glacier theory of the drift belongs, not to a native, 
but to an adopted citizen of this country. In the early 
papers of Agassiz, the conception of the Glacial period took 
a form which he himself later recognised as an exagger- 
ation. He conceived at first a fall of temperature so 
widespread that a polar ice-cap extended southward over 
the whole breadth of Europe and across the Mediterranean, 
reaching the Atlas Mountains. Later he recognised the 
ice-sheet that covered the Alps as entirely separate from 
the ice-sheet of northern Europe. The tendency to an 
exaggerated view of the Glacial period overcame him again 
in later years, when he maintained that, at the climax of 
the Glacial period, there was “ floating ice under the 
equator, such as now exists on the coasts of Greenland.”’ 
As Agassiz travelled in various parts of his adopted 
country, he recognised everywhere in the northern States 
the traces of glaciation, already familiar to him in Switzer- 
land and in Scotland. 
Within the last few decades the labours of earnest and 
able investigators have developed the glacier theory more 
in detail, and have added vastly to our knowledge of 
Quaternary history. The imaginary polar ice-cap has 
given place to ice-sheets of more limited dimensions, though 
still vast. The series of terminal moraines, marking 
stages of re-advance or halts in the retreat of the ice- 
sheet, have been carefully mapped. 
In early years the study of geology in this country was 
substantially confined to the region east of the Mississippi, 
but, in due season, the weird and fascinating region of the 
Cordillera revealed itself to explorers and geologists. It 
is now more than half a century since American geologists 
began the study of that western wonderland. The first 
lesson that geologists learned in that land was the 
efficiency of subaérial denudation to remove vast quanti- 
ties of material and shape the topography of wide areas. 
That western land has taught us, not only to recognise 
the fact of subaérial denudation, but also to formulate its 
methods. In Powell’s ‘‘ Exploration of the Colorado 
River,’’ he distinguished rivers as consequent, antecedent, 
and superimposed. Davis has carried the analysis some- 
what further, giving us subsequent and obsequent rivers. 
Powell formulated the doctrine of base-levels; Davis has 
given the conception greater accuracy and consistency by 
distinguishing base-level from profile of equilibrium. To 
Davis also we owe the full development of the conceptions 
of youth and age in river valleys and in drainage systems, 
and of cycles of erosion ending in the formation of pene- 
plains. 
Half a century ago the exploring expeditions connected 
with the Smithsonian Institution began to collect fossils 
from the Tertiary deposits of the western plains. Over 
those western plains were found to stretch vast continental 
deposits, certainly not all of lacustrine origin. These 
continental deposits of the western plains yielded in un- 
paralleled richness mammalian fossils, which have been 
studied by Leidy, Marsh, Cope, Osborn, Scott, Wortman, 
and others. No other single series of discoveries has been 
so potent in changing the bearings of paleontology upon 
the doctrine of evolution. 
In the half-century since the publication of Darwin’s 
first edition, the attitude of palzontologists has completely 
changed. Not only is it true at present that palzonto- 
logists are substantially unanimous in accepting the doc- 
trine of evolution, but it has come to be generally believed 
that the very science which afforded a half-century ago the 
NO. 1945, VOL. 75] 
} on opposite sides. 
strongest objection to evolution now affords its strongest 
support. 
When the first edition of the ‘*‘ Origin of Species '’ was 
published, the classes of birds and reptiles seemed to stand 
widely asunder. But in the very next year (1860) an odd 
feather of Archzopteryx was discovered, and a year later 
the skeleton now preserved in the British Museum; but 
Archzopteryx was a solitary representative of the birds 
of markedly reptilian character until the discovery of 
Ichthyornis and Hesperornis in the Cretaceous of Kansas, 
of which preliminary descriptions were published by Marsh 
in 1872. 
But the discoveries of most evolutionary significance, as 
already intimated, have been among the Tertiary mammals. 
A number of series has been traced, leading from 
generalised types in the Eocene, through forms of gradually 
increasing specialisation, to genera which still survive. 
Prenistoric ARCHAOLOGY.* 
Are eoliths artifacts? This is the fateful question. 
Their geological age is of no consequence if they 
are only natural forms, and have never been used by 
man or his precursor. ‘The first flakes to be utilised were 
in all probability natural forms. It is not likely that 
Eolithic man knew how to obtain the raw material from 
the chalk. He depended on picking up from the drift 
flakes of approximately the shape and size needed. A 
sharp edge was utilised once, twice, or until it became 
dulled, and was then cast aside. If an angular piece did 
not admit of being comfortably grasped in the hand, the 
troublesome corners were removed. Such conclusions as 
these are forced upon one after careful examination of a 
series of the specimens in question. Would the same con- 
clusions be so irresistible if these objects were merely 
nature’s playthings? Many may even be grouped accord- 
ing to more or less definite patterns. Two of these de- 
serve special mention, viz. the small crescent-shaped 
scrapers comparable to the spoke-shave, and the double 
scrapers with an intervening point between the two 
scraping edges. Sometimes two margins are worked, but 
That is to say, after chipping one of 
the margins, instead of rotating the specimen until the 
adjacent margin comes into play, it was reversed. 
The wide differences of opinion as to the origin of 
eoliths can hardly be due to prejudice alone. Faulty or 
insufficient observation and incorrect interpretation doubt- 
less play their part. Luckily, there is no disposition to 
drop the matter until the truth appears. At the Inter- 
national Congress of Anthropology and Prehistoric Arche- 
ology held at Monaco April 15-22, 1906, the chief sub- 
ject of the second session was the pedigree of the eolith. 
According to Nature (June 28, 1906, p. 211), “‘a series 
of mill-modelled flint nodules was exhibited, among which 
there was certainly a number closely resembling many 
Prestwichian types, but conspicuous by their absence were 
the decidedly purposeful and rationally usable Kentian 
forms.’’ On the other hand, Prof. E. Ray Lankester 
“submitted that he had recently placed on exhibition in 
the British Museum a _ considerable series (Amer. 
Anthropol. (N.S.), 1905, vii-, 432, 433) of specimens 
selected from Prestwich’s collection, all borer-like in form, 
too identical in shape and so rationally of obvious utility 
for any possibility of their being the result of fortuitous 
natural collisions.”’ 
As a further indication of the importance attaching to 
a correct solution of the problem, and indirectly in recog- 
nition of the value of Rutot’s contribution toward such a 
solution, the meeting of the German Anthropological 
Association for 1907 will be held in Cologne in order that 
the members may visit the eolithic stations of Belgium 
and see the collections of the Brussels Museum. 
Of caverns with Palzolithic mural decorations outside 
France, thus far reported, one is in Italy and four in 
Spain. The most important cavern in the Spanish group 
is that of Altamira, in the north coast province of 
Santander, this being the one in which the discovery 
of mural figures first took place. The genuineness of 
these figures would have continued to remain in doubt 
Some Puases oF 
1 From an address delivered by Prof. MacCurdy, chairman of the 
Section of Anthropology. 
