CAPE COD GEOLOGY 



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feet. A broad depression just west of the middle of the island gives rise to coves 

 on the opposite shore of the island. Tarpaulin Cove, on the southeast side, is 

 a well known anchorage in northeast gales for sailing vessels passing through 

 Vineyard Sound. Naushon remains largely covered by a native forest, which 

 corresponds closely with that growing on these islands when they were first 

 explored by white men. The soil is prevailingly sandy and the surface is encum- 

 bered with glacial boulders, some of them large and assembled in picturesque 

 groups. 



Hollick x has given a sketch of the glacial deposits of Naushon. He found 

 on the south shore of Nonamesset Island, near its east end, a bed of Cretaceous 

 lignitic and noduliferous parti-colored clay, and he gives a hypothetical cross 

 section of Naushon showing overthrust Cretaceous beds surmounted by bouldery 

 moraine. 



The forest comes down to the wind-swept shores in a bushy cover that 

 dwindles to a low scrub growth of plants and that protects the trees from the 

 harsh winds that strike the island. Plate 37, fig. 2, gives a view of the open 

 forest, free from undergrowth, as seen from a point on the south shore east 

 of Tarpaulin Cove. In this primeval forest deer keep down the undergrowth. 

 The flora appears to have come from the mainland and not from the islands 

 on the south, for Vineyard Sound has doubtless been an effective barrier to 

 the migration of plants between Marthas Vineyard and the Elizabeth Islands. 



Cretaceous Deposits 



The geology of Naushon was briefly described by Shaler, 2 who recog- 

 nized, beneath the surface moraine, a thick mass of fine sand, to which he had 

 already given the name "Naushon series," comparing it with the beds now 

 referred to the older Pleistocene on Marthas Vineyard. 



Cretaceous beds are exposed on the south side of Nonamesset Island at the 

 base of a small hillock that forms the eastern headland of Lakey's Bay. The 

 surface here carries large boulders, one of gneiss having a length of 18 feet. 

 Farther east, along the bluff facing Vineyard Sound, gravel that appears to lie 

 in beds that dip gently northwest is seen under a gray till having a compact 

 clayey matrix. A bed near by contains light, fine-grained sand. A section farther 

 east, about 20 feet high, reveals, beneath a top of gravelly, clayey till, a bed 



1 Hollick, Arthur, A reconnaissance of the Elizabeth Islands, Annals N. Y. Acad. Sci., 13, pp. 387- 

 418, pis. viii-xv, 1901. 



2 Shaler, N. S., Geology of the Cape Cod district, U. S. Geological Survey Eighteenth Ann. Rept., 



1896-97, Part II, p. 543, 1898. 



