40 GEOLOGY OF OHIO. 



history, it should include them, as this was a period of submergence of 

 the Mississippi and Ohio Valleys, and the time when the lake basin was 

 filled with water to the brim ; the time when the sediments brought 

 down by the rivers were deposited in sheets, out of which the streams, 

 with greater descent and more rapid flow, have cut the terraces that 

 border them. Professor Dana, in his papers on the Drift of the Connec- 

 ticut Valley, questions Hitchcock's conclusion that the terraces found 

 there are records of submergence, and were produced in the dead water 

 of an arm of the sea, and he attributes them to the great volume of 

 the rivers flowing from^ the melting glaciers. There can be no question, 

 however, that the terraces of the Ohio Valley were formed in quiet water. 

 This we learn from the accurate stratification of the materials composing 

 them. The section of the Valley Drift in Mill Creek Valley, at Cum- 

 minsville, given by Professor Ortoa (Vol. I, p. 433), is demonstrative of 

 this, for it is impossible that these stratified materials could have accum- 

 ulated here simply by current action. It may be further said that the 

 natural and inevitable effect of an immense increase in the drainage 

 flowing through the trough of the Ohio from the melting of the glaciers 

 without dead water to check it, would have been to sweep it clean through- 

 out its entire length. 



KAMES. 



The gravel hills which cover the summit of the divide between the 

 waters of the lake and the Ohio, present the most diflicult problem of 

 our surface geology. Their affinity with some of the Karnes and Eskers of 

 the British Islands, and the Asar of Scandanavia, is unmistakable ; and 

 if a satisfactory explanation of the origin of such of the Kames as re- 

 semble ours, had been offered by the European geologists, it would be 

 equally applicable here ; but no theory yet proposed fully satisfies the 

 conditions of the problem. The fact seems to be that the collections of 

 gravel and sand, which have been called Kames, are not all alike in 

 structure or history. Some of them are long and narrow ridges, located 

 in valleys or on comparatively low ground, and evidently mark the lines 

 of ancient sub-glacial rivers. The general character of these is well 

 shown in the map of the Asar, in the basin of Malar Lake, copied from 

 Tornebohm, on page 408 of Geikie's " Great Ice Age." Similar ridges, in 

 the valleys of the Connecticut and Merrimac, have been studied with 

 much care by Mr. Warren Upham, of the Geological Survey of New 

 Hampshire. He attributes these linear Kames, as do Tornebohm and 

 Hummel, in Sweden, to the action of sub-glacial rivers. By Professor 

 Dana, they are called sub-glacial moraines. Quite another kind of Kames, 

 although possibly produced by some modification of the same cause, are 

 the hills of sand and gravel which frequently occupy broad and high 



