ANCIENT WATER LEVELS OF CIT A MPLAIN— HUDSON VALLEYS 



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defined delta of sand with an ice contact slope, on the north mark- 

 ing the position of the ice front against which the deposit was 

 built by outflowing glacial water. The level of this deposit is 80 

 feet above the present sea, but in such relation to the surround- 

 ing geography that it clearly has been built in a temporary lake- 

 let held in back of the terminal moraine over the site of Manhasset 

 bay. 



Farther east and at the lower level of about 40 feet above the 

 sea, there is a much smaller delta with a kame habit on its north- 

 ern margin built as far as can be judged at a later stage in the 

 retreat of the ice sheet. The internal structure of this deposit 

 has shown a lower plane of w T ater level at about 35 feet. These 

 deposits on the northern flank of the terminal moraine have such 

 discordant levels for stages of deposition which must be regarded 

 as nearly though not exactly contemporaneous that it seems highly 

 improbable that their water levels coincided with sea level at 

 that time. 



Glacial delta near Perth Amboy. East of the railroad cross- 

 ing between Perth Amboy N. J. and Maurer at a point about 

 1000 yards south of Maurer station, a small rounded spur of sand 

 with an elevation of about 30 feet projects eastward and slightly 

 north on an cmbayment of the marsh of Arthur kill. The deposit 

 is a spur from the moraine-covered clay beds of the terminal 

 moraine. In 'the spring of 1901 this deposit was being cut away 

 for the sand which it contained. The section displayed in April, 

 when visited by Dr F. J. H. Merrill and myself, well defined top- 

 set beds from 3 to 4 feet thick overlying the truncated edges of 

 foreset beds dipping about 32 degrees east with a little northing, 

 displaying the typical structure of a delta, whose water level 

 must have been at about the 30 foot contour line according to the 

 reading by the map. 



The outer slope of this deposit is rather more subdued than in 

 the normal sand plain lobes of southern New England and sug- 

 gests modification by standing water. From the base there is a 

 slight projecting terrace 5 or feet above tide level. The form 

 of the whole deposit was so ill defined that without seeing the 

 cross-section I should not have taken it for a glacial sand plain. 

 It is evidently related to the deltas above described. 



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