444 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



Lewis and Wright. Near Meclianicsburg, in Butler County, there are 

 semistratified hillocks and ridges considered by them extramorainic, which 

 the writer has included in the moraine. In French Creek Valley the writer's 

 mapping of the morainic border agrees with theirs. 



In the Conewango Valley, at Ackley, the moraine presents a sharply 

 defined border, rising 50 to 75 feet above a plain which for several miles 

 north occupies the valley. For 3 or 4 miles below Ackley the valley is so 

 filled by morainic deposits that the stream is restricted in places to a passage 

 scarcely twice as wide as its bed, and is bordered by knolls rising 30 to 100 

 feet above it. The knolls are in groups, loosely connected and inclosing 

 kettle holes. As a whole, they present a very billowy appearance. Near 

 the south line of Pine Township, a mile or more below Russellburg, the 

 knolls are reduced to low swells and finally die away in a level terrace. 

 This terrace at its head stands about 30 feet above the river and occupies 

 the vallej^ from there to its mouth, descending somewhat faster than its 

 present flood plain. Bowlders are especially numerous near Ackley, and 

 are not rare on any part of the moraine between Ackley and the head of 

 the terrace. On the terrace none were obserA^ed. As determined by Lewis 

 and Wright, the moraine is finely developed on the slopes each side of the 

 Conewango and on the very elevated uplands.^ 



On the next A^alley west of the Conewango, that of Jacksons Run, the 

 moraine formed a complete obstruction to the passage of the stream and 

 constitutes a divide between streams flowing to the north and to the south. 

 Its best development is in the vicinity of the village of Chandlers Valley, 

 where kettleholes, sharp conical hills, and winding ridges of sandy till 

 abound. The ridges are about 20 to 40 feet in height. A mile below this 

 village is the head of the terrace formed by the glacial waters. Between the 

 head of this terrace and Chandlers Valley a portion of the drift deposits are 

 nearly level topped and have the appearance of a higher terrace, being 

 banked against the bluff. But out in the midst of the valley there are 

 knolls at lower levels than the high bench, and the terrace that leads down 

 the valle)^ heads among these knolls. The significance of the higher 

 bench was not detei-mined. 



On the uplands between Chandlers Valley and Little Brokenstraw Creek 

 the moraine is as finely developed on the elevated points as on the lower 



' Second Geol. Survey Pennsylvania, Rept. Z, p. 169. 



