LAKE ESCARPMENT MORAINES. 657 



RANGE IN ALTITUDE. 



The outer or south border of this morainic system is, throughout much 

 of its course, mucli higher than the inner border, because of its situation on 

 the face of an escarpment. The difference is only about 100 feet in the 

 Ohio portion, but in Erie County, Pa., it reaches 400 feet, and in Chautauqua 

 County, N. Y., fully 600 feet. 



In Ohio the altitude of the entire system shows scarcely 200 feet 

 variation, the lowest parts being about 775 feet above tide, and the highest 

 scarcely 950 feet. Indeed, it lies mainly between the 800- and 900-foot 

 contours. 



There is but little rise shown in crossing the Girard, Pa., quadi-angle, 

 but in the southwest part of the Erie quadrangle, north of Sterrettania, an 

 altitude of 1,000 feet is reached, and 1,000 to 1,100 feet is maintained along 

 the crest of the morainic belt in the central and eastern parts of the quad- 

 rangle. Between the Erie quadrangle and the New York line the crest of 

 the moraine rises to about 1,200 feet, and near the Westfield geodetic station 

 reaches an altitude of 1,480 feet 



In the valley-like depression at the head of Lake Chautauqua the outer 

 border of the moraine stands between 1,340 and 1,400 feet. On the divide 

 between Chautauqua and Bear lakes it rises slightly above the 1,500-foot 

 contour, but drops in the Bear Lake depression to 1,325 feet. Northeast of 

 Bear Lake it again rises to about 1,500 feet, and then drops to about 1,310 

 feet in the Cassadaga Valley. Near Arkwright it makes a still greater rise, 

 and appears on a hill north of the village that rises to the 1,740-foot contour. 

 In the valley east of Arkwright, near West Mud Lake, the altitude falls 

 to about 1,400 feet, some knolls being found between the 1,380- and 1,400- 

 foot contours. On the uplands between East and West Mud lakes an 

 altitude of 1,680 feet is reached. Around East Mud Lake morainic knolls 

 appear down to the 1,340-foot contour, but the crest north of the lake is 

 about 1,400 feet in its lowest part. Between East Mud Creek and Slab 

 Creek Valley the moraine rises to the 1,560-foot contour, but drops 200 

 feet in Slab Creek Valley, its crest being just above the 1,360-foot contour. 

 On the uplands between Slab Creek and the Conewango Valley it rises to 

 about the 1,600-foot contour. In Conewango Valley the crest is not far 

 from the 1,400-foot contour, but the outer face extends down to about 

 1,340 feet. It rises east of South Cattaraugus Creek to about 1,650 feet, 



MON XLI i2 



