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were successfully put down through 

 the fine sands and silts of the 

 lower Esopus valley so as to give 

 a fairly acceptable profile of the 

 rock floor [see fig. 7] . Esopus creek 

 in this portion of its course follows 

 the Hamilton shales escarpment 

 which forms a steep border on the 

 west side, while the east border of 

 the valley and floor are formed 

 by the underlying Onondaga lime- 

 stone. Gentle westerly dips prevail 

 for both formations, so that in the 

 perfect adjustment reached before 

 the glacial invasion a cross section 

 would have shown a typical unsym- 

 metrical valley — one side a gentle 

 dip slope and the other a bluff de- 

 veloped by the undercutting of the 

 stream as it shifted against the 

 edges of the shales. 



Results of exploration show that 

 the valley is filled to a depth of 

 more than 200 feet with silts and 

 sands that are essentially overwash 

 and glacial lake deposits. The flat 

 surface further favors this explana- 

 tion as had been pointed out before 

 any explorations were made. Later 

 observations in that portion of the 

 Rondout valley which is a continu- 

 ation of this structural feature indi- 

 cate similar deposits as far south 

 as the new line at Kripplebush, 10 

 miles away. 



In this instance at West Hurley 

 by careful measurement of dips on 

 the Onondaga limestone and the 

 Hamilton shales it was possible to 

 estimate the approximate depth to 

 which the Onondaga floor rock 

 would pass by the time the base of 



