1833.] SIBERIAN FOSSILS. 83 



Those tertiary epochs, which we are apt to consider as abounding 

 to an astonishing degree with large animals, because we find the 

 remains of many ages accumulated at certain spots, could hardly 

 boast of more large quadrupeds than Southern Africa does at 

 present. If we speculate on the condition of the vegetation during 

 those epochs, we are at least bound so far to consider existing 

 analogies, as not to urge as absolutely necessary a luxuriant vegeta- 

 tion, when we see a state of things so totally different at the Cape 

 of Good Hope. 



We know * that the extreme regions of North America, 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 f (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 wo 

 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 



* See Zoological Remarks to Capt. Back's Expedition, by Dr. Richardson. 

 He says, " The subsoil north of latitude 56 is perpetually frozen, the thaw 

 on the coast 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 nourish on the suri'ace, at a distance from the 

 coast." 



t See Hnmboldt, Fragmens Asiatiques, p. 38G : Barton's Geography of 

 Plants : 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. 



