V 
FOOD OF LARGE OUADRUPEDS 
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93 
many degrees beyond the limit where the ground at the 
depth of a few feet remains perpetually congealed, are covered 
by forests of large and tall trees. In a like manner, in Siberia, 
we have woods of birch, fir, aspen, and larch, growing in a 
latitude 1 (64°), where the mean temperature of the air falls 
below the freezing point, and where the earth is so completely 
frozen, that the carcass of an animal embedded in it is perfectly 
preserved. With these facts we must grant, as far as quantity 
alone of vegetation is concerned, that the great quadrupeds of 
the later tertiary epochs might, in most parts of Northern Europe 
and Asia, have lived on the spots where their remains are now 
found. I do not here speak of the kind of vegetation necessary 
for their support ; because, as there is evidence of physical 
changes, and as the animals have become extinct, so may we 
suppose that the species of plants have likewise been changed. 
These remarks, I may be permitted to add, directly bear on 
the case of the Siberian animals preserved in ice. The firm 
conviction of the necessity of a vegetation possessing a 
character of tropical luxuriance, to support such large animals, 
and the impossibility of reconciling this with the proximity of 
perpetual congelation, was one chief cause of the several 
theories of sudden revolutions of climate, and of overwhelming 
catastrophes, which were invented to account for their entomb¬ 
ment. I am far from supposing that the climate has not 
changed since the period when those animals lived, which now 
lie buried in the ice. At present I only wish to show, that as 
far as quantity of food alone is concerned, the ancient 
rhinoceroses might have roamed over the steppes of central 
Siberia (the northern parts probably being under water) even in 
their present condition, as well as the living rhinoceroses and 
elephants over the Karros of Southern Africa. 
I will now give an account of the habits of some of the 
more interesting birds which are common on the wild plains of 
Northern Patagonia ; and first for the largest, or South 
not penetrating above three feet, and at Bear Lake, in latitude 64°, not more than 
twenty inches. The frozen substratum does not of itself destroy vegetation, for 
forests flourish on the surface, at a distance from the coast.” 
1 See Humboldt, Frogmens Asiatiques , p. 386 ; Barton’s Geography of Plants j 
and Malte Brun. In the latter work it is said that the limit of the growth of trees in 
Siberia may be drawn under the parallel of 70°. 
