322 PRESERVATION OF BKEEETuXri. 



been formed under the sea, into which rivers 

 brought down the bodies of many animals ; of the 

 greater number of these, only the skeletons have 

 been preserved, but of others the perfect carcass. 

 Now it is known that in the shallow sea on the 

 arctic coast of America the bottom freezes,* and 

 does not thaw in spring so soon as the surface of 

 the land ; moreover, at greater depths, where the 

 bottom of the sea does not freeze, the mud a few 

 feet beneath the top layer might remain even in 

 summer below 32°, as is the case on the land with 

 the soil at the depth of a few feet. At still greater 

 depths, the temperature of the mud and water 

 would probably not be low enough to preserve the 

 flesh ; and hence, carcasses drifted beyond the shal- 

 low parts near an arctic coast would have only 

 their skeletons preserved : now in the extreme 

 northern parts of Siberia bones are infinitely nu- 

 merous, so that even islets are said to be almost 

 composed of them ;t and those islets lie no less 

 than ten degrees of latitude north of the place 

 where Pallas found the frozen rhinoceros. On the 

 other hand, a carcass washed by a flood into a shal- 

 low part of the Arctic Sea, would be preserved 

 for an indefinite period, if it were soon afterwards 

 covered with mud sufficiently thick to prevent the 

 heat of the summer-water penetrating to it, and if, 

 when the sea-bottom was upraised into land, the 

 covering was sufficiently thick to prevent the heat 

 of the summer air and sun thawing and corrupt- 

 ing it- 



Recapitulation. — I will recapitulate the principal 

 facts with regard to the climate, ice-action, and 



* Messrs. Dease and Simpson, in Geograph. Journ., vol. viii., 

 p. 218 and 220. 



t Cuvier (Ossemens Fossiles, torn, i., p. 151), from Billings's 

 Voyage. ' . 



