446 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



In the valley of the East Branch of Sugar Creek, a mile or more south 

 of Townville, the moraine is better developed than farther south, the valley 

 being open — i. e., more free from knolls — as the outer border of the moraine 

 is approached. No well-defined moraine-headed terrace was observed, but 

 leading down the valley is a broad plain slightly above the level of the 

 stream. This plain is the result of a gravel filling of 100 feet or more in 

 the old valley, and probably bears the same relation to the moraines as do 

 the more elevated moraine-headed terraces of other valleys. 



On the west or Lake Branch of Sugar Creek the moraine is finely 

 developed from Sugar Lake down to the Venango County line, where ter- 

 races set in. It carries numerous sharp conical knolls and sharp ridges, 

 among which basins are inclosed. Below Coopertown the moraine returns 

 to Sugar Creek Valley, where it is finely developed, though its knolls are 

 less sharp and numerous than on the uplands west of the creek. 



In French Creek Valley, from its mouth up to the Venango County 

 Infirmar}^, a distance of 5 miles, the moraine-headed terrace appears as a 

 smooth plain, standing about 50 feet above the level of the creek. Just 

 west of the infirmary an abrupt rise of 15 to 20 feet is made, and it has 

 above this point an vmdulating surface. Between the infirmary and Utica 

 there are places where the moraine resembles somewhat a pitted plain, its 

 surface having a nearly uniform altitude, 60 to 70 feet above the creek, 

 and being in some cases broad and level topped. Basins occur on it that 

 are depressed 10 to 20 feet below the general level of the glacial filling. 

 In places, however, it presents a hummocky topography. In explanation 

 of this peculiar topography it is suggested that the ice sheet may have 

 encroached upon an old terrace and only slightly modified the surface. 

 Above Utica the drift aggregations in the valley assume the ordinary 

 morainic type, there being numerous sharp knolls and winding ridges of 

 unequal height (15 to 60 feet), among which small basins 15 to 25 feet in 

 depth occur. 



The rate of fall of the stream increases near the outer border of the 

 moraine, but not in so marked a degree as on Oil Creek. According to 

 levels reported by White ^ the fall fi'om Meadville to the line of Crawford 

 and Mercer comities is but 20 feet in a distance of 12^ miles, while from 

 the Crawford County line to its mouth, a distance of 15 miles, there is a 



' Second Geol. Survey Pennsylvania, Eept. Q*, p. 26. 



