648 >J.\V \«>KK MAll, Ml >KU'M 



thU time very irregular in inUline as compan •! u Ifli tho. rr.'sf of tlie 

 inner moraine {»fe pi. l>).' 



As the land, on the Boutli of the Port Wasliintrtoii stage, on the 

 Ovster liav unadniiiirlo evervwiiere in the moraine rises to levels 

 higher than SO feet aliove the present sealevel but Is open to the 

 west, the nature of the body of water in which the deltas at this 

 Htage were builf - whether fresh water or sea water — must l)e 

 determiiKHl by observations dra^vn from outside the district. With 

 this jKiint in mind, the following notes from the Harlem and Brook- 

 lyn sheets throw light on the glacial history of this area. 



Harlem and Brooklyn quadrangles 



For the purpobe of comparison and in order to follow out to some 

 definite conclusion the problems arising on the area heretofore dealt 

 with, a recoimaissance was made of the region on the west. The 

 questions which have thus far arisen are the distinction between the 

 inner ami the outer moraine, the nature of the water body in which 

 the Port Wtuihington delta was deposited, and incidentally the rea- 

 son for the divii-inii of glacial drainage on the outwa^li plain into 

 Jamaica bay. 



It has l>een shown how the "inner " moraine becomes the 

 principal jind outer moraine west of Koslvn. From this vicinitv, 

 particularly near llollis, to the western limit of the island the aline- 

 ment of the front of the moraine at its merging into the sand plain 

 'i!> strikingly uniform in direction. From 2 to 3 miles east. and 

 west of Jamaica this line certainly is suggestive of an ancient shore 

 line, now at about 80 feet above the sealevel. 



A numl)6r of newly cut streets expose the glacial deposits along 

 this line, particularly on the crest and frontal slope of the moraine 

 in the vicinity of Januiica. The moraine near the front is composed 

 of till with medium-.sized boulders, often passing into an ill strati- 

 tied, contorted drift, with lenses of till and gravel, the topography 

 of the whole Injing of the knob and basin type. 



The frontal slo|)c of the moraine inclines from 15'' to 20°, an 



> On the colored geological mapacwmpanyiug this report, the deposit at Great 

 ^^ ' " ' '»* ""^ «llsrriiniimt.-<l from th<- older Mauhasset sands for the reason 

 II (jf fl,#- (Icpobit was obtiiinuble. 



