GLACIAL AND POST-GLACIAL HISTORY 431 



as Short Clove is approached. At its best the moraine shows a 

 rehef between hillocks and hollows of between 20 and 30 feet. (See 

 Fig. 9, No. 15). Some of the hillocks are composed largely of strati- 

 fied drift, but, so far as exposures show, a considerable part of the 

 moraine is made up of till which is prevaihngly of gneissx materials. 

 There are places, however, where it shows a conspicuous red color 

 from the abundance of Triassic constituents. 



2. The Haverstraw gravel plateau has been sometimes called the 

 Haverstraw delta. It extends from about the lower edge of the 

 moraine above mentioned north- 

 ward to Cedar Pond Brook, and 

 descends from an elevation of a 

 little less than 120 feet on the west 



to 40-60 feet on the east, where Fig. 10. — Cross-section of the Appa- 



it- falls off abruptly to a lower lachian VaUey (after Davis). 

 1 . 1 , . ,. li r- • vl5, uplands; Ci?, general valley lowland. Hori- 



plam bordering the Mmisceongo zontai lining shows day. 

 and Cedar Pond Brooks. 



The topography of the plateau for the most part appears at first sight 

 to be quite plain, with a general slope eastward and southeastward. 

 In the northern part, however, it becomes quite undulatory, and there 

 are some depressions as great as 20 feet in depth, one of which is 

 situated in a long conspicuous ridge extending north and south 

 parallel to the road west of it, leading from West Haverstraw to North 

 Haverstraw. This ridge is separated from the higher land to the west 

 by a considerable trough-like hollow. On closer examination much 

 of the surface, which at first sight appeared to be quite plain, is found 

 to be affected by ridge-like undulations and hollows with a rehef of 6, 

 8, and 10 feet These undulations extend eastward nearly to the 

 abrupt east front. (See Fig. 5, ^.) 



Structure and materials: Exposures are abundant in this plateau. 

 In the higher western portion numerous gravel and sand pits show 

 stratified sands and gravels more or less horizontal in the upper few 

 feet, and dipping at high angles below in an easterly and southerly 

 direction. A little eastward these stratified gravels are said to over- 

 lie clay, and still farther eastward exposures are of such a nature that 

 it is quite certain that the gravels and sands grade into finer materials, 

 and into clay with alternate layers of fine sand, and finally into the 

 laminated brick clays. 



