188 



CLIMATE OF THE MAMMOTH 



[Ch. X. 



1823, that a slow upheaval of the land along the borders 

 of the Icy Sea is now constantly taking place, similar to that 

 experienced in part of Sweden. In the same manner, then, 

 as additions have been made to the shores of the Gulf of 

 Bothnia, not only by the influx of sediment brought down by 

 rivers, but also by the elevation and consequent drying up of 

 the bed of the sea, so a like combination of causes may, in 

 modern times, have been extending the low tract of land 

 where marine shells and fossil bones occur in Siberia.* Such 

 a change in the physical geography of that region, implying 

 a constant augmentation in the quantity of arctic land, would, 

 according to principles to be explained in the twelfth chapter, 

 tend to increase the severity of the winters, and, by limiting 

 the supply of food, finally contribute to the extermination of 

 the mammoth and its contemporaries. 



On referring to the map (p. 182), the reader will see how 

 all the great rivers of Siberia flow at present from south to 

 north, from temperate to arctic regions, and they are all 

 liable, like the Mackenzie, in North America, to remarkable 

 floods, in consequence of flowing in this direction. For they 

 are filled with running water in their upper or southern 

 course when still frozen over for several hundred miles near 

 their mouths, where they remain blocked up by ice for six 

 months in every year. The descending waters, therefore, 

 finding no open channel, rush over the ice, often changing 

 their direction, and sweeping along forests and prodigious 

 quantities of soil and gravel mixed with ice. Now the rivers 

 of Siberia are among the largest in the world, the Yenesei 

 having a course of 2,500, the Lena of 2,000 miles ; so that 

 we may easily conceive that the bodies of animals which fall 

 into their waters may be transported to vast distances towards 

 the Arctic Sea, and, before arriving there, may be stranded 

 upon and often frozen into thick ice. Afterwards, when the 

 ice breaks up, they may be floated still farther towards the 



* Since the above passage was first 

 printed in a former edition, June 1835, 

 it has been shown by the observations of 

 Sir E. Murchison, M. de Verneuil, and 

 Count Keyserling, and more recently 



by M. Middendorf (see above, p. 185), 

 that the Lowland of Siberia has actually 

 been extended since the existing species 

 of shells inhabited the northern seas. 



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