ANCIENT WATER LEVELS OF CHAM PLAIN— HUDSON VALLEYS 99 



had its times of slight advance, it is but natural to expect slight 

 frontal deposits built against the northern slope of the Palisade 

 ridge where its course turned so as to lie athwart the path of 

 ice motion. Such deposits actually occur. 



The morainal deposits of this stage are well shown at the Haver- 

 straw station on the West Shore Railroad. The material is a 

 reddish till in a thick deposit lying approximately between 100 

 and 200 feet above the sea from the vicinity of the railroad sta- 

 tion to and beyond the limits of the Tarrytown atlas sheet. The 

 conditions of the ice front at this time are indicated in the 

 accompanying cross-section drawn across the front between High 

 and Little Tor [fig. 8]. South of High Tor this morainal coating 

 fails to appear as a flanking deposit on the iceward side of the 

 trap ridge. As will be described in some detail presently, 



Fig. 8 Diagrammatic cross-section showing relation of ice sheet to frontal moraine 

 at Haverstraw : below cliff, the moraine; to the right, clays, sands and gravels 



morainal deposits reappear in the northern part of Croton point 

 and it is therefore reasonable to suppose that the ice front left 

 the west bank of the river in the vicinity of Short or Long Clove 

 and crossed the Hudson gorge to the east bank, curving or pro- 

 jecting southward in mid-channel. 



While the ice lay in the Hudson gorge south of Short and Long 

 Clove, these two passes across the Palisade ridge would have 

 afforded an outlet for the lateral drainage flowing between the ice 

 on one side and the trap wall on the other. The long straight 

 course of the Hackensack from the Cloves down to West Nyack 

 is so well developed as to suggest that the stream may have been 

 enlarged in the glacial period by water pouring through these 

 passes, which lie at about 200 and 220 feet above the sea. 



About i of a mile south of the West Shore bridge over 

 Minisceongo creek and east of the railroad there was a sand 

 knoll exposed in 1900 in which stratified sands from 40 to 60 



