ANCIENT WATER LEVELS OP CHAMPLAIN-HUDSON VALLEYS 89 



Unglaciatcd area of Staten Island. Two very distant small 

 tracts within the State of New York lay beyond the reach of 

 the last ice advance ; one in the extreme southwestern part of the 

 State, the other an area about half a square mile in extent at 

 Garretsons and Grant City on the southeastern face of the 

 serpentine hill of Staten Island. On a sloping shelf ranging from 

 120 to about 250 feet above the sea lies an ancient pre-Wisconsin 

 surface of weathered products surrounded on the northwest by 

 the terminal moraine and on the southeast in the low grounds 

 by the outwash gravels of the Wisconsin ice sheet. The iron 

 crusts segregated in the weathering of the bed rock encumber a 

 reddish soil unmixed with exotic material and topographically 

 unaffected by any sign whatsoever of other agents than the 

 meteoric conditions to which the areole is now exposed. The 

 soft erodable materials form an escarpment descending from the 

 120 foot line to approximately the 50 foot contour line along 

 which they disappear beneath the fresh gravel of the last ice 

 advance. It is difficult to admit a transgression of the sea, how- 

 ever slight, over this surface without some trace of its action 

 being left behind. This area appears to the writer as a monument 

 of long continued land conditions, beginning before the Wisconsin 

 epoch. 



Far Rochaway ridge, Long Island. The outwash plain of the 

 terminal moraine on the south side of Long Island is interrupted 

 at Linwood by a singular ridge of gravels which extends south- 

 westward to Far Eockaway inclosing behind it Jamaica bay. In 

 a recent publication of the museum I recognized this deposit as 

 being older than the terminal moraine and its outwash plain, and 

 from my failure at the time to find granitic pebbles in the gravels 

 referred the deposit to the pre-Pleistocene series. At about the 

 same time Professor Salisbury ^ in a publication of the United 

 States Geological Survey described the deposit as a shallow water 

 formation practically contemporaneous with the outwash plain 

 thus including it in the Wisconsin epoch and inferring from it the 

 presence of the sea, if I understand his position correctly, at a 

 somewhat higher level than now along the southern border of 

 Long Island. Later I visited the ridge with Messrs Fuller and 



^Salisbury, R. D. New York City Folio. U. S. Geo!. Sur. 1893. 



