88 NEW YORK STATE MUSEUM 



Keene, called by the writer " Keene hill." Here the altitude is 1113 

 feet. Farther north we find the outlet channel spillway at 1155 feet. 

 This level, compared with the 1 100-foot delta above mentioned, 

 gives on calculation a deformation of 2.94 feet a mile. 



Outlet. Once more we must depart from the Lake Placid quad- 

 rangle and consult the Ausable sheet to find the outlet. As can be 

 inferred from figure 6 an ice lobe lay in the valley of the East 

 branch of the Ausable river with its southern wall at Lower Jay. 

 Another body of ice blocked the narrow valley now occupied by 

 Trout pond. Thus northward escape was prevented. The waters 

 of the lake found outlet to the east through the gulf, a narrow and 

 deep faultline valley, south of Ellis and Black mountains. In this 

 interesting channel there are a number of Pleistocene cataracts, but 

 unfortunately the topography is incorrectly drawn and they fail to 

 appear on the survey map. At the eastern end of the gulf, on the 

 boundary between the townships of Jay and Chesterfield, the river 

 turns to the southeast making a series of little ponds, which are really 

 plunge basin lakes at the base of former cataracts. Of the group 

 the remarkably beautiful Copperas pond is the most striking 

 example. 



Beaches versus stream terraces. Below the Wilmington lake 

 level, on the mountain slopes, in the Ausable valley, a number either 

 of benches or stream terraces have been found and their altitudes 

 measured. The question of origin arises, naturally, in individual 

 cases. Many of them are probably shore-line features formed by 

 glacial lakes, while others are stream meander terraces formed by the 

 postglacial Ausable in cutting its way through the glacial sands. 

 A discrimination between the two is often impossible, thus leaving 

 the identification of succeeding lake levels extremely unsatisfactory. 

 Typical examples are the levels on the " Keene hill," a mile directly 

 north of Keene (see plate 25). The following are the altitudes 

 the writer has obtained by the use of two aneroid barometers checked 

 against a barograph and spirit leveling: 1146, 11 13 (Wilmington 

 beach), 1037, 1017.7, 993.9, 985.7, 925.7 feet. The mean height of 

 the river at this point is 816 feet. The origin of the lower ones is a 

 disputed question. D. W. Johnson regards them as stream terraces, 

 while Fairchild and Chadwick attribute them to glacial lakes. 



Another series, in the Ausable sheet, i]^ miles northeast of 

 Lower Jay on a similar hill (the "Lower Jay hill"), has been 

 recorded as folbws: 1046, 1043, 1024, 997, 917.5, 908 (wave-cut 

 clifif), 880 and 857 feet. The river is a mile distant to the west, 



