CLEVELAND MORAINE. 623 



west of Lake Chautauqua, there being a difference of more than 700 feet 

 in the altitude of ridges and valleys. The altitiide of the high points on a 

 dividing ridge between Cassadaga and Conewango creeks, in northwestern 

 Gerry, eastern Charlotte, and western Cherry Creek townships, in Chau- 

 tauqua County, is 2,040 to 2,100 feet, as shown by the Cherry Creek 

 topographic sheet, while the broad valleys of Cassadaga Creek on the west 

 and. of Conewango Creek on the east of this elevated strip are below the 

 1,300-foot contour. As both of these valleys are open to the north, the ice 

 sheet was free to extend into them from the Lake Erie Basin. There is a 

 strong probability that it extended down Cassadaga Valley to the mouth of 

 the creek and down Conewango Valley to the vicinity of Kennedy; but 

 it probably fell short several miles of reaching as far south on the inter- 

 vening uplands and also on the high uplands between Cassadaga Valley 

 and Lake Chautauqua. 



The entire valley of Cassadaga Creek and the part of Conewango 

 Creek above Kennedy have broad bottoms standing only a few feet above 

 the creek beds, portions of which are still subject to overflow. Along the 

 borders of each of these valleys, and also on the borders of the valley in 

 which Lake Chautauqua lies, there are accumulations of graA'elly, partially 

 assorted drift which rise 40 to 75 feet above the broad bottoms. They are 

 slightly undulatory and in places carry shallow basins. The topography, 

 structure, and position of these deposits seem best explained on the hypo- 

 thesis that the valleys were filled by tongues of ice at the time they were 

 accumulating. The hypothesis that these benches are remnants of a filling 

 which once extended entirely across the valleys was considered and found 

 to be untenable, for such an erosion as it would call for is greatly out of 

 proportion to the erosion farther down these drainage lines. The hypothesis 

 that the benches represent the borders of a lake was also considered and 

 found to be unsatisfactory. The deposits are evidently to a large extent 

 glacial. The water action which they display seems to be such as might 

 occur in connection with drainage along the border of ice tongues, and 

 not such as would occur on the shore of a narrow lake. The basins and 

 the low swells on these benches give them a striking resemblance to the 

 head of glacial terraces. An examination of the part of the Conewango 

 below Kennedy shows the valley to be occupied by a pitted gravel plain 

 which stands at about the same height as these benches. This pitted gravel 



