216 R. S. TARR — MORAINES OF SENECA AND CAYUGA LAKE VALLEYS 



results of this study will appear in the forthcoming Watkins Glen Folio, 

 to which reference is made for local details, omitted from this generalized 

 outline. 



General Topography 



The distribution of the moraines is to such a marked extent dependent 

 on the topography that a description of the main topographic features 

 is necessary for an understanding of the moraines. 



In general the region is a dissected plateau, with hilltops rising from 

 1,700 to 2,000 feet above sealevel, and valley bottoms in some cases 

 below sealevel. The hills in the north are lower and less rugged than 

 those in the south, so that the general upland surface slopes downward 

 toward the north. 



There are three major valleys on the Watkins Glen quadrangle — the 

 Chemung valley, which extends east and west, and the two north-and- 

 south valleys which, in their northern portions, are occupied by Cayuga 

 and Seneca lakes. Between the two lake valleys, which on the quad- 

 rangle are about 18 miles apart, is a highland region of rugged topogra- 

 phy, especially in the south, and between the lake valleys and the 

 Chemung valley there is such an absence of marked divides that the 

 present divides are determined by drift deposits, not by rock topography. 

 These two north-south valleys have had a profound influence on glacial 

 motion, and consequently on the nature and position of the morainic 

 deposits. 



Seneca and Cayuga Lake valleys are almost exact counterparts of one 

 another. Both broaden toward the north and have less steeply rising 

 valley walls in that direction. In both cases there is a lower steepened 

 slope at approximately the 900- foot contour, along which there is a series 

 of mature hanging valleys. Above the level of the hanging valleys and 

 steepened slope the main valley walls are far less steep and more mature 

 in form, making a broadly open upper valley, with a gorge-like trench 

 in the bottom, whose width is about 2 miles at the top and whose depth 

 in the Seneca valley is at least 1,400 to 1,500 feet, and in the Cayuga 

 valley 850 feet below the level of the hanging valleys. 



Direction of Ice Motion 



On the uplands, away from the influence of topographic irregularities, 

 the striae have directions indicating a general ice movement from the north- 

 east (north 45 degrees to 60 degrees east); but the valleys have deflected 

 the ice in many instances. This is especially true of the Cayuga and 

 Seneca troughs, in which the striae are prevailingly parallel to the valley 

 walls. Since the lake valleys have a direction somewhat west of north, 

 these striae indicate a deflective influence of the valley troughs, sufficient 



