106 GEOLOGY OF OHIO. 



ing sufficient velocity to transport such a mass of coarse material several 

 hundred miles, would not be shown simply in such transportation, but 

 these currents would deeply excavate the underlying beds over which 

 they flowed, and which were at this time scarcely in any degree consoli- 

 dated. 



Shore waves acting upon this portion of the continent could not have 

 effected such a distribution, as they have no power to create quartz peb- 

 bles except as they have quartz rock to work upon. Advancing shore 

 waves could, therefore, not have deposited two or three hundred feet of 

 sand and gravel several hundred miles out upon a flat, composed alto- 

 gether of fine material; and retreating shore waves would have no power 

 to carry with them from Canada to Kentucky such a mass as the Con- 

 glomerate forms there. We must, therefore, find some other process of 

 distribution than any yet suggested for the explanation of the problem 

 before us. 



In looking through the geological series for some similar deposit which 

 could serve as an explanation of this one, I have found none that seemed 

 to offer so close a parallel as the later Drift deposits spread over the 

 northern half of the Mississippi valley. Here we have in many locali- 

 ties a mass of material which, if consolidated, would form an almost 

 perfect copy of the Carboniferous conglomerate — beds of gravel, in which 

 the pebbles are for the most part quartz, undistinguishable from those 

 of the Conglomerate and sheets of sand, nearly or quite free from peb- 

 bles. It is true that most of the Drift also contains bowlders of larger 

 size than any found in the Conglomerate, but over large areas these are 

 restricted to the summit of the series, and mark a distinct epoch in the 

 chain of events. Throughout a wide area, too, we find the gravels and 

 sands of the Drift resting upon the lower, fine Drift clays, precisely a3 

 the Conglomerate rests upon the mud stones of the Waverly and the 

 Sub-carboniferous limestone. To explain the phenomena presented by 

 the Drift deposits, I have been compelled to invoke the aid of floating 

 masses of ice, and have suggested that the gravels and sand which form 

 the upper layers of the Drift have been floated to their present resting 

 places, frequently from points of origin 500 miles distant, and quietly 

 dropped down upon the soft clays below; arguing that currents of water 

 or currents of ice transporting these gravels, sands, and bowlders, could 

 not have deposited them where they are found without tearing up the 

 underlying clays. 



All that we know of the present sea bottom on the banks of New- 

 foundland leads us to suppose that it is every where strewed with gravel, 

 sand, and bowlders, spread with considerable uniformity over its surface 



