WELL DEFINED LATERAL MORAINES 219 



cause of the greater complexity of the topography. The two lower mo- 

 raines, one on and near the 1,000-foot contour, the other about 100 feet 

 higher, are not distinctly traceable on the more hilly eastern side of the 

 Seneca valley, while on the western side of the Cayuga valley they are 

 apparently merged into a single broad moraine. 



Below the lower of these two moraines, on both sides of each valley, 

 there is absolutely no development of moraine deposit. Thus while 

 above the lowest moraine there is much moraine topography for a ver- 

 tical distance of 800 to 900 feet, below it, through a vertical distance of 

 500 to 600 feet, there is no moraine. 



The lateral moraines vary greatly in component material, from till to 

 gravel, and in topography from hummocky kame moraine or well defined 

 ridges to gently undulating sag and swell topography. One remark- 

 able feature about these moraines is the low rate of inclination of the 

 ice margin which they prove. In a distance of 9 miles, between Wat- 

 kins and the northern edge of the quadrangle, the lowest moraine 

 scarcely descends at all, and in the same distance the next higher mo- 

 raine descends a little less than 200 feet. This low rate of descent of 

 the ice margin is doubtless due to the fact that the ice tongue, backed 

 by a great ice sheet, pushed freely up these smooth-walled valleys ; and 

 the difference in rate of descent of two neighboring, nearly parallel mo- 

 raines is probably the result of the fact that at the higher stages the ice 

 was less distinctly under the influence of the inclosing valley walls. In 

 both cases the low rate of descent indicated by the lateral moraines 

 contrasts strikingly with the rate at which the ice margins descended 

 into other smaller valleys. 



The higher lateral moraines are far less regular and simple, but they, 

 too, indicate a moderate slope for the ice-tongue margins. Their lack 

 of simplicity is explained by the fact that hills rose across the path of 

 the ice, forming nunataks at some of the stands, while the broader val- 

 leys of the uplands caused a deflection of the ice margin up lateral 

 valleys and in some cases across lowered divides down the open valleys. 



During the highest stands of the ice the main valley tongues extended 

 south of the present divides of Cayuga and Seneca valleys, reaching 

 farthest south along the more open valley south of Seneca lake. North 

 of the divides, in the bottom of each of the lake valleys, there is a maze 

 of complex morainic topography, toward which the lateral moraines 

 lead by a series of moraine terraces. 



Frayed Moraines 



On the sides of many of the valleys tributary to the Seneca and Cay- 

 uga troughs there are steeply descending ridges, sometimes composed of 



