ANCIENT WATER LEVELS OP CHAMPLAIN-HUDSON VALLEYS 101 



Corner in a sheet of outwashed detritus, the position of which on 

 the clays shows its more recent deposition. The precise age of 

 these gravels and sands can be fixed in terms of the glacial retreat 

 with precision, for the northern margin of the coarse detritus 

 in the 100 foot plain at North Haverstraw shows clearly, by the 

 ice contact slope of the terrace, that the deposits were along that 

 line banked up against the edge of the glacier which still lay 

 in the Hudson gorge. The age of the terraced remnants of the old 

 delta is therefore fixed as nearly the same as that of the moraine 

 at Haverstraw and earlier than all the various frontal deposits 

 yet farther up the river in the line of retreat. 



While the Cedar pond brook deposits are thus considered here 

 as connected with the Croton point stage of the retreat it has to 

 be recognized that the ice edge on the west side of the river had 

 retreated from the moraine at Haverstraw station to the northern 

 edge of the delta at North Haverstraw, a distance of 2 miles. 



The clays underlying the Haverstraw gravels and sands are 

 normal glacial deposits, evidently made in more or less open water 

 the surface of which must have been at least 50 feet above the 

 present sea level, but as the clays are overlain by the delta 

 deposits made at the time the ice sheet pressed against the gravel 

 bank at the North Haverstraw station, they can not be associated 

 with deposits made at a later time when the river was freed of 

 ice as far north as Albany. The precise age of the clays at Haver- 

 straw is necessarily somewhat in doubt. North of the old delta 

 with its ice contact at the North Haverstraw railroad station 

 clays lie in the low grounds quite up to the south side of Stony 

 Point. The clays rise up in the small hillock south of that point 

 and evidently have there been much eroded. South of them rises 

 the bluff of gravels in the North Haverstraw delta on which clays 

 have not been deposited. Everything in this locality points to the 

 conclusion that the clays are here older than the Cedar pond 

 brook delta and that the ice sheet rested on these clays when the 

 delta began to build. It is not so clear that the upper clays south 

 of the Cedar pond brook were also in existence before the ice sheet 

 retreated to the north shore of Cedar pond brook. 



As previously shown on page 80 clays will begin to deposit 

 along an ice front somewhat in advance of the sands and gravels 



