44 NATURAL HISTORY OF 



models upon which the indigenous civilization of the 

 new world was based and progressing, notwithstanding 

 the vicissitudes of international wars and conquests, 

 until the arrival of the Spaniards laid the whole wes- 

 tern fabric in the dust.* 



ARCTIC ASIA. 



BEHRING'S STRAIT is generally of a trifling depth, 

 scarcely forty miles wide, having several denudated 

 and abrazed islands intervening; and the coasts, in 

 many parts, composed more of frozen earth than solid 

 rock. As the water, with several shoals, is floored 

 with fossil bones and shells, and there being no river 

 of importance on either shore of the continents, or 

 near, on the Arctic side, no great pressure can have 

 come from the polar ocean ; and consequently, no great 

 opening, if any, until the Arctic rising of Asia and 

 Europe altered the relative conditions of the two seas. 

 That once there was no current, may be inferred from 

 the islands of New Siberia, and the vicinity being in 

 part composed of ice, mixed with mammoth bones, 

 tusks, and other organic remains, and the presence 

 of several species of land mammals, common to both 

 continents, attests a facility of passing from one to 

 the other, to have been effected by several of them 

 on the ice. 



While the foregoing statements sufficiently demon 

 * See Addenda. 



