THE GEOLOGY OF LONG ISLAND, ETC. 



Two outcrops of Cretaceous materials occur on the west 

 side of Cold Spring- Harbor, one one-half mile south of 

 Cooper's Bluff, the other opposite the village, one-half mile 

 northwest of the sandbar. Above are the Wisconsin stage 

 deposits consisting of till, stratified gravel, and also white 

 sand, yellow, white and salmon colored clays. On the east 

 side of the harbor are abandoned clay pits, south of Lloyd 

 Beach which connects Lloyd and West Necks. Here occur 

 diatomaceous deposits, and Cretaceous plant fossils, (see list), 

 indicating a past land connection with New England. Our 

 knowledge of the fossil flora of Long Island is mostly due 

 to the researches of Hollick ('93-'12) with Newberry 

 ('86) Ries, ('84) and Jeffrey ('06-'08) adding important 

 contributions. 



Following the laying down of Cretaceous and Tertiary 

 materials, (clays, sands, gravels and marls), along the east- 

 ern borders of the north American continent an era of ele- 

 vation began, which raised them hundreds of feet above 

 their present level, forming a wide coastal plain which ex- 

 tended into what is now a part of the bed of the Atlantic 

 Ocean, probably at the 100 fathom contour. It is thought 

 to have been bounded on the land side by the crystalline and 

 Triassic rocks of Connecticut, southern New York and Penn- 

 sylvania. There is reason to believe that its limits were ap- 

 proximately that of the coast line today. This area will be 

 seen to include the whole of Staten Island, Long Island, 

 Block Island, Martha's Vineyard and Nantucket besides a 

 large portion of the submerged coast, eastward and south- 

 ward. 



The ensuing erosion was first normal, and resulted in 

 the formation of an inner lowland where Long Island Sound 

 occurs. The erosion of this inner lowland was continued to 

 the point where a well developed cuesta was formed and it 

 is to the further accumulation of glacial materials upon the 

 summit of the cuesta, that Long Island owes its present 

 marked contrast between rugged moraine and abrupt high 

 shores on the one hand, and smooth southern plain, with 

 low reedy, flat southern shores on the other. The scouring 

 action of the ice sheet further deepened the inner lowland, 

 and with the final disappearance of the ice sheet from the 



—17— 



