LAKE ESCARPMENT MORAINES. 663 



From the bend of Mill Creek south of Erie, Pa., eastward nearly to 

 the north end of Lake Chautauqua, N. Y., this niorainie system, as above 

 noted, is combined into a single strong belt. Along its south border there 

 is often a somewhat sharp ridge forming the crest line of the belt and 

 standing 20 to 30 feet or more above the immediate border. Where the 

 moraine crosses Sixmile Creek there is a small ti'act of level land lyiug 

 between it and the escarpment to the south. A similar low plain at Sixteen- 

 mile Creek is traversed by the creek for a mile or more near Grahamsville. 

 In western Chautauqua County, N. Y., there is a similar narrow plain 

 several miles in length which has been utilized by Twentymile Creek in its 

 westward course. 



From this ridge northward down the face of the escarpment the drift 

 knolls are distributed singly or in groups. They are often so closely 

 aggregated as to give the face of the escarpment a hummocky appearance, 

 but in places are scattering. The lower part of the escarpment generally 

 has fewer knolls than the upper part. 



From the New York line eastward to the Westfield geodetic station 

 numerous shallow basins were found among low swells along or near the 

 crest of the moraine. Such basins are less numerous, though not rare, in 

 Erie County, Pa. 



The outer moraine in the depression at the head of Lake Chautauqua 

 is a gently iindulating till ridge, with swells scarcely 10 feet in height, 

 among which there are numerous saucer-like depressions. At the south 

 border it stands only 8 or 10 feet above a gravel plain that leads down to 

 Lake Chautauqua, being near the 1,340-foot contour, but the crest in places 

 reaches the 1,400-foot contour. It is not certain, however, that this relief 

 of 60 feet is entirely due to drift accumulations; possibly the crest follows 

 in part a rock ridge. 



The topography of the outer moraine in the Bear Lake Valley is 

 somewhat different from that in the Chautauqua, there being only scattering 

 knolls without a well-defined basement ridge. The outer of the two moraines 

 which lead from the Cassadaga Valley toward Arkwright consists of a gently 

 undulating till ridge which, for a couple of miles northeast from Cassadaga 

 village, forms a divide between a southward-flowing and a westward-flowing 

 tributary of Cassadaga Creek, as indicated in PI. XIX. 



The inner or main moraine from the head of Lake Chautauqua eastward 



