ANCIENT WATER LEVELS OF CHAM PLAIN— HUDSON VALLEYS 129 



level. These three deposits are traversed by the road from Voor- 

 heesville to Meadowdale. 



This falling off in the level of terrace and sand plain building 

 from west to east, from 380 to 3G0 and then to 340 feet indicates 

 a lowering of the water level dependent on the opening of lower 

 gaps between the ice front and the escarpment on the east. These 

 levels of construction so like the effects of ice-confined waters are 

 within the zone of altitude affected by ice on the east bank of the 

 Hudson in the Schodack district and lie above the broad clay 

 plains immediately west and south of Albany and are thus clearly 

 above any marine limit which has left a mark in this field. 



At South Bethlehem the upper level of these Albany clays is 200 

 feet, near Voorheesville it is about 300 feet; in the dunes south of 

 Schenectady the hight is about 360 feet, the precise elevation 

 having been affected by the erosion and deposition of the fine sands 

 by the action of winds in the postglacial epoch. The rate of fall 

 from Voorheesville to South Bethlehem is about 1 foot to the mile 

 for a distance of 10 miles, from the vicinity of Schenectady to 

 Voorheesville a rate of somewhat less than 1 foot in a distance of 7 

 miles. 



North A lbany gravels. Between Albany and Loudonville on the 

 north side of Patroons creek there is a high ridge of morainic 

 aspect with long kettles and a boulder-strewn surface. These 

 general characters are traceable northward beyond Ireland 

 Corner. This deposit certainly antedates the Mohawk delta stage, 

 and indicates by its form and structure that it was made during 

 the occupation of the valley by ice, and is undoubtedly to be corre- 

 lated with the lateral glacial terraces at Schodack and South 

 Bethlehem or to a sligMly later stage. The rise of the ridge to 

 300 feet or over in close accordance with the level of the Schodack 

 terrace suggests that the remnant of the glacier in this district 

 may have been sheeted over with flood plains of gravel, w r hile the 

 depressions were filled with the same material. 



At the southeastern foot of this ridge in Xorth Albany the, 

 clays are seen resting unconformably on these older glacial grav- 

 els. The gravels are locally very coarse and bouldery, layers of 

 small boulders up to 1 foot and even 15 inches in diameter being 

 seen well up in the section. The beds have a strong dip toward 

 a depression on the north of this locality as if they had settled. 



