10 NEW YORK STATE MUSEUM 



The Hoosic river, which has its sources on the western slopes of 

 the mountainous region of the I'T'ew York-New England border, 

 enters the quadrangle in the northeastern quarter of the sheet and 

 flows in a meandering course westward and northward, discharging 

 into the Hudson at the head of the rock channel at Stillwater. The 

 river valley except for a short length west of Johnsonville, is every- 

 where bordered by deposits of sands and gravel. Westward from 

 Schaghticoke the river penetrates an immense mass of fine gravels 

 and coarse sands which clearly originated as a delta built by the 

 river into the body of waters that occupied the Hudson valley in 

 late glacial times. The delta formation is of the characteristic 

 triangular shape and at its base, fronting the Hudson valley, has a 

 breadth of about 7 miles. Its areal extent may be estimated at 20 

 square miles. 



In its course through the delta the present river is flanked by a 

 series of terraces which rise at successively higher levels to the 

 general summit level of the Pleistocene clays of the Hudson valley. 

 A fuller description of the Hoosic delta, together with a discussion 

 of its development and that of the system of terraces, will be given 

 further on in this report. 



A valley of exceptional interest from the standpoint of Pleisto- 

 cene history is that which enters the Hudson valley from the west 

 at Mechanicville. It is occupied by a small stream, Anthony kill, 

 which in its present size is quite out of proportion to the breadth 

 and depth of the valley. Anthony kill is the outlet of Round lake 

 (see map, p 46) which in turn receives the outlet stream of Balls- 

 ton lake, the latter lying at the bottom of a preglacial channel that 

 communicates with the valley of the Mohawk east of Schenectady. 

 There is quite conclusive evidence^ that in late glacial times waters 

 from the flooded Mohawk river coursed through this system of 

 channels, discharging into the waters of the Hudson valley at 

 Mechanicville. At a later time the Mohawk became established in 

 its present course, and Anthony kill, draining the old channel as 

 far back as the divide at the head of Ballston lake, is the shrunken 

 remnant of the much larger stream through whose erosive work 

 the present relatively large valley was formed. 



As in the case of the Mohawk river, Anthony kill, entering the 

 Hudson from the west, runs athwart the ancient rock valley of the 

 Hudson. From Willow Glen eastward the floor of the valley is 



^ Stoller. Op. cit. p. 29-31 ; Fairchild. Pleistocene Uplift of New York 

 and Adjacent Territory. Bui. Geol. Soc. of Anier., 27:251. 



