664 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



presents topograph}^ similar to that toward the west, there being in places 

 a naiTow ridge scarcely an eighth mile in width and 30 to 40 feet or more 

 in height forming the crest, while numerous hummocks and basins appear on 

 its inner border for about a mile north from the crest. Such a sharp-crested 

 ridge is a conspicuoiis feature for 2 or 3 miles in the part of the moraine 

 immediately west and north of Bear Lake, as may be seen by reference to 

 the Dunkirk topograpliic sheet (see PI. XIX). Just outside this sharp 

 moraine is a smooth gi-avel plain. 



On the slopes north and northwest from the upper Cassadaga Lake 

 there are a few drift knolls 20 to 40 feet or more in height, among which are 

 numerous small ones only 5 to 10 feet high. In Cassadaga Valley a gravelly 

 tract occurs around the upper and lower lake, which carries a few low knolls 

 and presents apparently a gradation from the moraine into a plain that sets 

 in south of the lower lake. 



On the high ridge near Arkwright the moraine has a hummocky surface, 

 with numerous knolls 10 to 15 feet and a few 20 or 25 feet in height. This 

 topography extends down the slope eastward to West Mud Lake. 



The vallej'' below West Mud Lake carries a smooth gravel plain, but 

 near the lake it becomes full of basins, the largest of which is occupied by 

 the lake. They extend up to the moraine which forms the divide north 

 of the lake, and which presents a sharply ridged surface. North from the 

 morainic crest sharp knolls occur for a mile or more. Many of the knolls 

 are small, being onlj'- 10 to 15 feet in height and covering only an acre or 

 two. There are basins among them that occup}' only a few square rods, 

 yet are several feet in depth. 



The hummocky topography leads eastward over the ridge to East Mud 

 Lake, where the moraine presents features similar to those around West 

 Mud Lake, there being a gradation from the gravel plain south of the lake 

 through basins in and around it to the sharp-crested moraine that passes it 

 on the north. The basins on the border of the lake are 8 to 10 feet deep 

 and only a few acres in extent, but the lake itself occupies a basin nearly an 

 eighth of a mile across. 



From East Mud Lake eastward to Perrysburg knolls 20 to 30 feet high 

 are quite numerous and are arranged in chains with trend in line with the 

 moraine, or nearl}' east to west. The tendency to an east-to-west ridging 

 becomes still more conspicuous in the area extending from Perrysburg 



