1872.] DAWKINS CLASSIFICATION OF PLEISTOCENE STRATA. 429 



Eussia are equally dependent upon the season for their locality ; and 

 if an unusual season occurs, to put the animals off their accustomed 

 route, the inhabitants of the district at the mouth of the Kolyma, living 

 upon the chase, endure the severity of famine. M. von Matiuskin, 

 the lieutenant of Admiral von "Wrangel, had the good fortune to see 

 one of the migratory bodies of Reindeer, consisting of many .thou- 

 sands divided into herds of two or three hundred each, in the act 

 of crossing a river. Ey some such oscillation of temperature which 

 regulates the supply of food for the herbivores, the remains of the 

 animals of two contiguous zoological provinces may be found to- 

 gether in one spot, as in the case of the northward retreat of the 

 Musk-sheep, which, living in Hearne's time (a.d. 1770) near Fort 

 ChurchiU, has left that district to be occupied now by the Elk and 

 Wapiti. In this manner the admixture of the remains of a»tiimals 

 living at the present day respectively in a severe and in a temperate 

 continental climate may be accounted for in the Pleistocene caverns 

 and brick-earths. Sir John Eichardson writes : — "' The subsoil 

 north of lat. 50° is perpetually frozen, the thaw on the coast not 

 penetrating above 3 feet, and at Great Bear Lake, in lat. 64°, not 

 more than 20 inches. The frozen substratum does not of itself de- 

 stroy vegetable life ; for forests flourish on the surface at a distance 

 from the coast, and the brief, though warm, summer gives birth to 

 a handsome flora, matures several pleasant fruits, and produces many 

 carices and grasses." The climatal extremes of temperature are 

 -very great, the minimum winter temperature at Fort EeUance, on the 

 northern shore of the Great Slave Lake (N. lat. 62°50", long. 109° W.) 

 being registered by Capt. Back, 17th Jan. 1834, as being —70°, and 

 the maximum at the end of May -1-106°. These observations are 

 confirmed by those of Sir John Franklin, at Fort Franklin (lat. 65°, 

 long. 123°), where, on Dec. 25, 1826, the temperature was — 43°, and 

 on the 31st May -f- 93°. Such a great variation as this could not 

 have happened in the latitude of Britain, France, or Germany ; nor 

 is it required by the circumstances of the case. 



In the vast plains of Siberia also, extending from the Altai Moun- 

 tains to the Arctic Sea, we find a near approach to the Pleistocene 

 climate of North-western and Central Europe. Covered by impene- 

 trable forests, for the most part of birch, poplar, larch, and pine, and, 

 in the north, of low creeping dwarf cedars, they present every grada- 

 tion in climate, from the temperate to that in which the cold is too 

 severe to admit of the growth of trees, which decrease in size as the 

 traveller advances northwards, and are finally replaced by the grey 

 mosses and lichens that cover the low marshy tundras. The minimum 

 temperature registered by Admiral von Wrangel at Nishne Kolynisk 

 on the banks of the Kolyma is — 65° in January. " Then breathing 

 becomes difl&cult, the wild Eeindeer, that citizen of the polar region, 

 withdraws to the deepest thicket of the forest, and stands there 

 motionless, as if deprived of life, and trees burst asunder from the 

 intensity of the cold. Throughout this area roam Elks, Black Bears, 

 Foxes, Sables, and Wolves, that afford subsistence to the Jakutian 

 and Tungusian hunters. In the northern part countless herds of 



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