116 



NEW YORK STATE MUSEUM 



whole the deposit bears the closest analogy to the high terrace at 

 West Point at the base of Crow's Nest mountain and occurs just 

 where the waters ponded in the Walkill valley would escape along 

 the ice border at the most favorable stage into the Hudson gorge. 

 The much lower level of terraces on the north at Roseton and New 

 Hamburg compels the belief that all the terraces in the Hudson 

 gorge were deposited along the margin of a local protrusion of 

 the glacier and thus lie above the level which standing water in 

 the open gorge would have assumed at this time. 



Northward near the mouth of the Moodna kill where the terrace 

 still has an elevation of 160 feet there is a deposit of gravel and 

 sand overlying stratified clays. The interesting terraces in this 

 part of the kill are described on page 199. 



Newburg terrace. The city of Newburg on the west bank of the 

 Hudson is built on a splendid terrace whose structure and conse- 

 quently its glacial history are somewhat complex. 



The terrace is most perfect on the northern bank of Quassaic 

 creek where its elevation is about 150 feet. The front facing the 

 river appears to have been eroded by the natural action of the 

 river, though it is now largely artificial by reason of railway exca- 

 vation and buildings which have been arranged along it. 



Setting out from Washington's headquarters, the geologist pro- 

 ceeding southward traverses a depression leading to the river, 

 beyond which he surmounts the best preserved portion of the 

 terrace, which in an east and west section shows the profile given 

 in the figure on p.117. In this section, the terrace presents 

 the form of a glacial plain, deeply cut away on the outward or 

 river side, and bounded on the west by topographic features which 

 are distinctly due to the deposition of the materials in the pres- 

 ence of ice in the valley of Quassaic creek. The head or iceward 

 margin of the plain is slightly mounded as if by the pressure of 

 the ice, and the slope into the valley on the west is cast in the 

 form of kames and mounds. In fact the country on the west and 

 northwest as viewed from the terrace presents a field of kames 

 drained by the Quassaic quite as distinctly contemporaneous with 

 the ice sheet as those which have been described in the valleys of 

 the Chenango and other streams. 1 



^righam, A. P. Glacial Flood Deposits in Chenango Valley. Geol. Soc. 

 Am. Bui. 1897. 8:17-30. 



