through the passes of the 



210 Geology of the Lakes and the Valley of the Mississippi. 



But these two estuaries, though the principal, wer'e not the only 

 ones. The rolled pehhles found along the water courses leading to 

 them, are found also along the shores of every river which flows 



Alleghany from the table^ land of the 

 lakes. They are found on the Hudson, the Delaware, and the Sus- 

 quehannah ; and they are not found on any river which descends 

 trom either flank of that mountain. Portions of the great diluvial 

 current must, therefore, have cleft it at the places occupied by those 

 rivers. No feebler power could have cut their channels out. They 

 could not themselves have done it. The disuniting force must have 

 ■been applied at vastly higher levels than they could have attained 

 by fining up the vallies ; and the evaporation from the expanse of 

 surfaces thus produced, would have nearly equalled the quantity ol 

 water returned to them in 

 little comparatively to tumble over the ridges. But what power 

 could there have been to sustain a mass of water at an elevation 

 sufficient to cause an overfall at any point of the principal or divi- 

 ding ridge, without which no fresh water stream could make its way 

 through that barrier or produce the stupendous results observable in 

 every member of the chain ? An ocean beating against its side might 

 perforate it; but it is infinitely more probable that the breaches were 

 effected even before the mountains had raised their heads above the 



rain, so that there would have been hut 



d 



eep 



We have no district so rich in results and yet so imperfectly ex- 

 plored as the country of the upper lakes. There, will probably be 

 discovered the records of those grand changes that have been made 

 in the structure and condition of the continent to fit it for the re- 

 ception of its ultimate and permanent inhabitants ; and there, too, 

 will probably be found the bones of the saurians and other relicta 

 of the European lias, establishing, beyond contradiction, the con- 

 temporaneous deposition of that formation wherever it is loun . 

 The vertebrated land animals, bemnnins^ in the middle or perhaps 

 low^er tertiary, belong also to all the posterior periods, and in many 

 cases, are subsequent even to the diluvium. With us, they n^ i 

 morasses, which rest upon it. and in postures indicative of a peace- 

 ful death and subsequent state of repose. At the Blgbone hck m 

 Kentucky, the bones of the mastodon were commingled in the same 

 layer with those of the bison of the present time. What seems de- 

 cisive of the period of their existence, is that they are found only 



