630 GLACIAL FORMATIONS OF EEIE AND OHIO BASINS. 



Returning to tlie head of Pymatuning Valley in Ohio and taking up the 

 inner member, we find a belt of low knolls 10 to 20 feet in height leading 

 across the uplands to the northwestern end of Pymatuning Swamp near 

 Pennline, Pa. Among these knolls is a very prominent one which was 

 utilized by the United States Lake Survey as a geodetic station. It stands 

 about a half mile north of West Andover, on the east slope of Pymatuning 

 Valley, its base being slightly below the level of the uplands. It rises 

 abruptly about 90 feet above its western and 70 feet above its eastern base. 

 Its longest diameter is about one-fourth mile and it trends north to south 

 On the knoll two basins occur near its highest point. This knoll commands 

 a view of Lake Erie, though distant fully 20 miles. Its highest point is 

 1,191 feet above tide, or about 620 feet above Lake Erie. 



Near Pennline, Pa., are several knolls 40 to 50 feet in height, which 

 are nearly conical in form and very abrupt. About a mile south of Penn- 

 line two large knolls stand end to end, with a trend northwest to southeast, 

 or about in line with the ice movement. They are fully 40 feet in height. 

 Another knoll of similar height appears about a half mile southeast of 

 them, while among these large knolls are numerous small ones, so that the 

 moraine is especially well defined here. South of these knolls is a gravel 

 plain, formed probably as an outwash from the moraine, which leads down 

 the Shenango Valley. It contains shallow basins near the moraine, but is 

 smooth farther south. 



The most prominent knolls in the line w;hich follows the northeast side 

 of Pymatuning Swamp are found on the farm of Jacob Frey, 2 miles west 

 of Linesville Two were noted which have a height of 45 to 50 feet above 

 the swamp in which they stand. At the southeastern end of the swamp, 

 near Hartstown, there is a cluster of lai'ge drift knolls standing on the eastern 

 slope, which covers about a half of a square mile and includes several which 

 are 75 to 100 feet in height. East of this group, near the residence of 

 D. M. Calvin, there is an isolated knoll about 90 feet in height, which rises 

 very abruptly, its base covering scarcely 5 acres. It has been opened 

 extensively for gravel by the Erie Railway Company. It is to this knoll 

 that White makes reference in his report on Crawford County.^ A few low 

 knolls occur along the east side of Crooked Creek Valley for a mile or more 



^Second Geol. Surv. Pennsylvania, Rept. Q*, p. 148. 



