Address before the Association of American Geologists. 251 



Eighthly, water must have been one of the forces employed 

 in this agency. The regular deposits of clay and sand which 

 form the upjjer part of the diluvial deposit, must surely have 

 been accumulated at the bottom of bodies of water, which have 

 subsequently been drained off. Much, also, of the finer part of 

 our drift is more or less stratified, and exhibits that oblique lamin- 

 ation which is pecuUar to aqueous deposits. Nor can I conceive 

 of any other mode in which detritus has been transported hun- 

 dreds of miles, as ours has been, but by the aid of water ; al- 

 though this alone could not do it. In New England, we have 

 been able to trace erratic blocks not more than one hundred or 

 two hundred miles, because we then reach the ocean. But in 

 the central parts of the country, I am informed by Prof. Mather, 

 that the primary bowlders from Canada and the western part of 

 JMichigan, are found as far south as the river Ohio ; which would 

 make their maximum transit from four hundred to five hundred 

 miles ; about the same distance as the bowlders from Scandinavia 

 have been carried into Germany. What agency but water could 

 have effected such a transportation ? 



It is very natural, also, to ascribe the smoothness and furrow- 

 ing of the rocks to the action of water. But I have in vain ex- 

 amined the beds of our mountain torrents and the shores of the 

 Atlantic, where the rocks have been exposed to the unshielded 

 and everlasting concussion of the breakers, and can find no at- 

 trition that will compare at all with that connected with drift ; 

 and I am satisfied that to explain it we must resort to some other 

 agency. 



Ninthly, ice must have been another agent employed to pro- 

 duce the phenomena of drift. What else could have transported 

 large blocks and gravel over such a wide space as has been men- 

 tioned, and have lodged them too, upon the crests of narrow and 

 precipitous ridges ; and especially, what other agent could have 

 produced those singular mounds and peculiar ridges of gravel and 

 bowlders that meet us in so many places ? 



Tenthly, this agency must have been exerted previously to the 

 existence of man upon this continent, and have been of such a 

 nature as to destroy organic life almost entirely. For the remains 

 of man and other existing animals have not been found in drift ; 

 but those occurring there belong chiefly to extinct species, while 

 the deposits of clay and sand made during the same period, 

 scarcely contain a species of animal or plant. 



