REVIEW OF GEOLOGICAL STRUCTUKE. 41 



surfaces, presenting a billowy outline to the eye, and frequently holding 

 lakelets in the depressions which separate them. The Karnes of Ohio, 

 are generally of this kind, although some of them are elongated ridges. 

 They occupy, however, here, a topographical position which makes it 

 impossible that they should ever have been the beds of rivers, for they 

 form a belt along the summit of the divide between the lake-basin and 

 the Ohio Valley, all the way across the State. Their altitude is from 

 400 to 600 feet above the lake, i. e., 1,000 to 1,200 feet above the oeean» 

 and some of them rise nearly 100 feet above their bases. They are com- 

 posed of gravel and sand, sometimes horizontally stratified, more 

 generally as interlocking wedges. They contain but few large bowlders, 

 and the gravel of which they are composed is well rounded; it is derived 

 from both indigenous and exotic rocks. The Bowlder clay is usually ab- 

 sent where the Kames are found, and they rest on the underlying rock ; 

 but they are occasionally seen to spread over the Till, and are evidently 

 of more recent date. 



In the notice of the Kames given in Chapter XXX, it was suggested 

 that they may have been formed by the action of shore-waves, when the 

 lake-basin was filled to the brim and they were islands or shoals. This 

 view is not sustained by any conclusive evidence, but was offered as a 

 possible and even probable explanation of a problem of difficult solution. 

 That they are not moraines, properly speaking, is certain, as they have 

 not the form, composition, nor structure of moraines. They occupy the 

 summit of the water-shed, and in their stratification and the rounding 

 of their pebbles, distinctly show water action ; therefore, although com- 

 posed of material which may be morainic, it has been all rolled and re- 

 assorted. The pebbles and bowlders contained in the Kames, are such 

 as are found in the bowlder-clay, but rounded and worn so that scratches 

 and angles have been removed. Everything indicates that they are 

 composed of the coarser material of the Till, triturated and rounded by 

 water, which washed out the clay. 



Professor Geikie, in the second edition of his "Great Ice Age," page 

 469. suggests that the Kames of the summit of our water-shed are formed 

 by sub-glacial rivers and the great quantity of water pouring from 'the 

 glacier when it filled the lake-basin. This is an explanation that would 

 satisfy some of the conditions of the problem, but, unless we imagine 

 the glacier to have remained for a very long period precisely at this 

 stage, it is difficult to see why the washing effect of the water draining 

 from it should be so localized. It will be remembered that this belt of 

 Kames, along the highlands, divides two areas of Bowlder clay, where no 

 gravel-beds, just like these, are found. In the lake-basin there is nothing 

 at all like them, and in southern Ohio, the only hills of gravel which 



