ALDEN MORAINE. 685 



The knolls that are associated with the ridges are often quite sharp, but 

 are only 10 to 30 feet in height. 



At the western end of the moraine there are numerous small basins 

 bordered by gently imdulating gravelly tracts. The appearance is some- 

 what similar to that of the pitted gravel plains found as an outwash from 

 the ice sheet. The outwash seems to have been directly into lake water, 

 for the pitted plain stands at about the level of the beach of Lake Warren. 



STRUCTURE OF THE DRIFT. 



In structm-e the Alden moraine is similar to the Marilla, the greater 

 part of the drift being a clayey till. Limestone jDebbles and also large 

 blocks are conspicuous ingredients of the till, and surface bowlders are 

 numerous. 



OUTER BORDER DRAINAGE. 



It is probable that the glacial drainage from the vicinity of Tonawanda 

 Creek to the western terminus of the moraine was westward. For a few 

 miles it was through narrow channels among the knolls and ridges of the 

 Marilla moraine; but from near Fargo, in Darien Township, Grenesee County, 

 westward to Alden Center, there is a jjlain 1 to 2 miles in widtli which stands 

 near the level of Lake Warren, and which probably carried a shallow ba)' 

 into which the glacial waters discharged. 



RELATION TO LAKE WARREN. 



To the north and east from this moraine there seems to be but a single 

 beach of Lake Warren, the Lower Forest or Crittenden, while to the south 

 and west there is a more complex system. The moraine seems therefore to 

 correlate with a somewhat lengthy part of the Lake Warren history. This 

 matter is considered more fully in the discussion of the beaches of Lake 

 Wan'en. 



PEMBROKE RIDGES. 

 DISTRIBUTION. 



Under this name is discussed a complex system of sharp gravelly knolls 

 and ridges which leads eastward from the west part of Pembroke Township, 

 in western Genesee County, to the Batavia moraine in western Batavia 

 Township, a distance of about 10 miles. They are in part shown on PI. III. 

 There are usually two, and in places three, ranges of knolls, each trending 



