Geology of Long Island. 355 



interrupta, Crepidula fomicata, *6 y . plana, Tomatella punch- 



striata, Bulla canaliculata, * Venus mercen aria, * Ostrea Virgin i- 

 ana, Pecten Islandicus, P. Magellanicus, Area transversa, A. 

 pexata, Cardita boreal is, *Astarte sulcata or undata, Mactra la- 

 teralis, Lucina radula, *Mya arenaria ; fragments of a Bala- 

 n us ; a coral, Astrangia Dana}. 



Napeagne Beach, east of Amagansett, is three miles long and 

 one quarter of a mile broad, consisting entirely of white quartz 

 sand. Along the shore on the north and south are dunes of 

 drifted sand 20 or 30 feet high, but the main portion of the 

 beach probably averages less than 10 feet above the sea. East 

 of the beach, the country for twelve miles to the end of Montauk 

 Point, is chiefly a terminal moraine, and as such I have already 

 briefly described it. 



Historical Geology. 



Having thus reviewed in detail the various strata underlying 

 the drift, we come now to consider their age and history. With- 

 out attempting to decide the geological equivalence of the crys- 

 talline rocks at Astoria, we will discuss the nnsolidified deposits 

 which have just been described. 



From the position and strike of the Cretaceous strata in New 

 Jersey and Staten Island, it has been surmised by geologists that 

 they underlie Long Island throughout the whole or a portion of 

 its extent. The locality at which the strata most resemble 

 the Cretaceous beds of New Jersey is Glen Cove, where the 

 clays already described are probably of this age. If the Cre- 

 taceous formation extends under the whole of Long Island it 

 must occur at a very great depth, since deep sections at points 

 east of Glen Cove do not reveal its presence. 



In regard to this formation and the following, it should be un- 

 derstood that sufficient data have not yet been obtained to war- 

 rant an attempt to map out their extent. The only exposures 

 are in vertical sections along the shore and in various clay-pits 

 or similar excavations ; and there being an immense amount of 

 quaternary material overlying them, no satisfactory degree of 

 accuracy can be as yet attained in this regard. 



* Species also collected by the writer. 



