74 NEW YORK STATE MUSEUM 



observed near the summit of a knoll of pre-Cambrian rock. It is 

 not certain whether the movement was to s. 30° e. or to n. 30° w. 

 though in all probability the former. 



Near White creek, 2^ miles north of Middleville, one of the 

 tributary creeks just uncovers, in its bed, the summit of a hill 

 capped by Trenton limestone, on which are plentiful striae bear- 

 ing n. 80°e. Since this is a hill summit, no rock showing in the 

 banks, and none in the bed either above or below, it should give 

 the general ice direction, and accords well with the records nearer 

 the Mohawk. 



The only possible criticism to be made on Professor Chamber- 

 lin's quoted statement is that it might lead the reader to hold 

 the view that general glaciation in the Adirondacks was not 

 severe and long continued, and such view is certainly erroneous. 



In general, the glacial deposits are not exceedingly bulky over 

 the limits of the sheet, and over much of it they are very thin, the 

 underlying rocks not only outcropping along the streams but 

 repeatedly in the interstream areas. The drift is heaviest in the 

 northwestern part of the district, where the rocks are effectively 

 concealed over many square miles. There is also heavy drift 

 north of Dolgeville. 



Till. The till varies much in character, the variation being 

 mostly in the rock ingredients, which are mainly of quite local 

 origin, as is usual. In and near the pre-Cambrian area it is 

 rather light colored and excessively sandy, and this is its 

 character throughout the Adirondack region. Elsewhere it is 

 nearly black and much less stony, which is due to its large con- 

 tent of soft, black Utica shale. It seems to acquire large depth 

 only where filling preglacial valleys. The black till is magnifi- 

 cently exposed in the banks of West Canada creek and many of 

 its tributary creeks from the east, often forming perpen- 

 dicular cliffs up to 100 feet and more in hight. There are 

 also high till banks in Spruce creek north of Dolgeville, and in 

 the creek tributary to East Canada at Ingham Mills. In these 

 the till is overlain by heavy sand deposits, at the base of which 

 large springs issue. 



