700 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



30 feet in height and abont 2 miles in length, including small gaps. The 

 northern half has a nearly due north-south trend, but the southern half bears 

 southwestward. The topographic map shows the ch.ange in trend l^ut fails 

 to bring out the esker form which it presents. 



From near Chili northeastward to the bend of Coldwater or Little Black 

 Creek there is a sandy belt about 1 mile wide and 3 miles in length, which 

 has a knob-and-basin topography. Its highest points .stand about 60 feet 

 above Little Black Creek. The topographic features as well as the sandy 

 material suggest wind action, but bowlders were found embedded in the 

 sand and on its surface, which seem to indicate that the features are only to 

 a minor degree due to the wind. Glacial action seems to have been the 

 main agency. The intricacy of this belt is brought out to a fair degree b}* 

 the topographic map. South of this sandy belt from Chili eastward to the 

 Genesee River is a gently undulating till tract, with knolls usually but 10 

 to 15 feet in height, while to the north the surface is even less undulatory 

 and carries scarcely any sand. This sandy belt has about the same trend 

 as the striae of that vicinity, and meets the remainder of the moraine 

 obliquely. It is in a nearly direct line of continuation of the Pinnacle 

 Hills ridge of Rochester, but is separated from it by a gap about 4 miles in 

 width, which is partly occupied by a latei' moraine. The presence of this 

 moraine is thought to indicate that the Pinnacle Hills ridge was formed 

 later than the Chili sand belt. 



STETJCTURE OF THE DRIFT. 



In the Barre moraine, as well as its associated spurs, eskers, etc., there 

 is a large amount of gravel and sand. Indeed, till seems to predominate 

 over assorted material only for a few miles east fr(„mi Lockport. The ridges 

 there as well as the plains are principally till. Farther east there seems to 

 be considerable till in plane tracts, but the ridges are chiefly gravel. The 

 most prominent ridges are usually thickl)- strewn with bowlders, but tliey 

 are not so numerous on the low ridges and on plane tracts. Among the 

 bowlders, which are largely of granitic rocks, there are not a few limestone 

 slabs gathered from the immediate vicinity. 



The drift is ordinarily so thick along the line of this moraine that 

 wells are obtained without entering rock. There are, however, small areas 

 around Shelb}' Center and Barre Center as well as farther east where the 

 drift is very thin, so that the rock ledges are within reach of the plow.. 



