GLACIAL BAMS, LAKES, AXD WATERFALLS. 379 



since the upper limit has the same elevation above tide (1,045 

 to 1,065 feet) at every locality. 



These deposits consist of rounded bowlders of sandstone, 

 with a large amount of clay, quicksand, and other detrital 

 matter. The country rock in this region consists of the soft 

 shales and limestones of the upper coal-measures, and hence 

 there are many "low gaps" from the head of one little stream 

 to that of another, especially along the immediate region of the 

 river ; and in every case the summits of these divides, where 

 they do not exceed an elevation of 1.050 feet above tide, are 

 covered with transported or terrace material ; but where the 

 summits go more than a few 7 feet above that level we find no 

 transported material upon them, but simply the decomposed 

 country rock. 



A fine example of one of these bowlder-covered divides may 

 be seen at the mouth of the Youghiogheny River, back of Mc- 

 Keesport, Pa. The "divide" in question is one between the 

 water of Long Run. which puts into the Youghiogheny, two 

 miles above McKeesport, and that of another little stream 

 which heads up against it, and flows into the Monongahela 

 within the city limits. The divide between these two water- 

 ways, although 275 feet above the level of the river, is almost 

 imperceptible in a broad and bowlder-covered valley through 

 which there is not the slightest doubt that the waters of the 

 Youghiogheny once flowed during an epoch of submergence.* 



Passing farther down the Ohio Valley, we find a most 

 interesting exhibition of this high-level slack-water depo- 

 sition in Teazes Valley, Putnam county, W. Va. This val- 

 ley runs from the Kanawha Eiver, a little below Charleston, 

 to the Ohio at the mouth of the Guyandotte, near Hunting- 

 ton. The valley is clearly enough a remnant of the early 

 erosion which sculptured the whole country. The water of 

 the upper Kanawha evidently at one time took this course 

 to the Ohio. The valley is very clearly marked, and its 

 main features can be taken in by any one riding over the 

 Chesapeake and Ohio Railroad between Huntington and 



* "American Journal of Science," vol. exxxiv, 1887, pp. 378, 379. 



