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POPULAR SCIENCE REVIEW. 
sion. In this country, and indeed in any country but Green- 
land, we cannot do so. Take Mr. James Geikie’s 66 Great Ice 
Age,” as the hook which most fully — though still not so fully as 
it might — treats of these questions, and there is work enough 
for a geologist lying ready at his hand. 
What is the nature of the material lying under the great ice 
cap of Greenland ? Is it the counterpart of the Scottish boul- 
der clay or till ? Are the finely-laminated clays forming in the 
Greenland ice fjords from the mud-laden streams which flow out 
from beneath the glaciers the same as the brick clays of Scotland 
and elsewhere, as the present writer has shown to be highly 
probable? Again are the Greenland fjords, as are the fjords 
in other parts of the world, due to the wearing action of ice, 
when they formed the beds of great glaciers as Nordens-kjold 
and I have argued ? Again, the whole question hinges on the 
theory — not a theory, I believe, but an established fact, but still 
opinions differ — in regard to the eroding power of ice. In 
studying ice — sea and land — alone the geologist would be very 
fully and profitably occupied for a couple of years. 
Another question for him to try and solve is this — Is Green- 
land rising in the North, while we know well that it is sinking 
in all the region south of Wolstenholme Sound ? Are the terraces 
you find on the shores of Smith’s Sound evidences of this general 
and gradual uprising of the shores going on, or are they only 
like the terraces you find on the shores of Greenland south of 
Melville Bay, which we know are evidences of a former uprising, 
not of one now going on, for at the present time I find others 
have shown* there are indubitable signs that a gradual sinking 
of the coast is in progress. Mr. James Geikie — a most competent 
authority on all questions touching glacial deposits — suggests 
to me that “ it would be very interesting to have determined 
whether the raised beaches of Greenland give any indication of 
changes of climate such as have been observed in these deposits 
in Spitzbergen. Great banks of Mytilus edulis , Cyprind islan- 
dica , and Littorina littorea , occur in that island, and none of 
these species are ever found living in the Spitzbergen sea. It 
is true that Mytilus is occasionally seen attached to algae in 
these regions, but such rare birds are but poor representatives 
of the banks of the same shell which are met with in the same 
island. Mr. Nathorst, of the Swedish Geological Survey, tells 
me that in 1870 he examined these shell-banks, and found one 
made up of Mytilus resting upon a scratched rock surface (now 
far removed from any glacier), and the scratches ran parallel 
withHhe fjord. The Mytilus still lives in Greenland, as does 
* Thy sics of Arctic Ice, <l Quart. Journ. Geol. Soc.,” vol. xxvii. (1871); 
Pop. Sc. Rev., August 1871. 
