224 



DYNAMICAL GEOLOGY. 



The map, page 211, affords illustrations of these barriers. Montauk Point has its 

 beach, and also its bluffs of sand and coarse gravel. Westward, the beach is continued on in 

 a series of barriers, outside of a series of shallow bays, which extend all the way to Coney 

 Island and New York Bay. The barrier is seldom over GOO yards in width, and is almo.st 

 wholly bare, yet has stumps at places on tlie inner side. Moreover, the westward drift 

 of the sands has shallowed the waters south of the western part of Long Island. The 

 zigzags here in the 10- fathom bathymetric line show the direction of the wave-and-current 

 movement. 



Part of the drifted sands of these beaches were supplied from the bluffs to the east- 

 ward, but part are the gatherings of the waves from the sea-bottom below the beach and 

 barrier, and a small part are from the feeble streams of southern Long Island. 



Along the New Jersey coast and farther south the beaches are usually half a mile to 

 a mile in breadth, and many have an inner forest-covered belt. Sandy Hook — 5 miles 

 in length — owes its existence to the drifting of the sands, and an accompanying inside 



current, continued through both the ebb and flow 

 196. of the tide, as long since explained by Bache. 



The drift of the Atlantic coast is here carried to 

 the very margin of the deepest ship channel out 

 of New York Bay. The hook-like shape of the 

 extremity may be due to drift in the Long Island 

 direction where that of the New Jersey direction 

 is forced to stop. 



Coiist-regiou of North Carolina; CK, Curri- 

 tuck Inlet (to Currituck Sound) ; N, New 

 Inlet; H, Cape Hatteras ; O, Ocracock 

 Inlet; C, Cove Inlet; L, Cape Lookout. 



Fig. 196 is a map of the coast-region 

 either side of Cape Hatteras (H). Along 

 the coast south of New York the rivers 

 carry out a large amount of detritus, 

 which is widely distributed, but the coarser 

 is gathered up by the waves to make the 

 barriers. The position of the cape was 

 probably determined by a cape of rocky 

 ridges which is now submerged. Off the 

 great Middle Bay of the Atlantic coast the 

 storm-winds have their greatest velocity 

 when blowing from the eastAvard — as 

 they do at the Bermudas ; and hence the 

 course of the wave-and-current movement 

 is toward New York Bay, both along 

 southern Long Island westward and from 

 Cape Hatteras northward. South of Cape 

 Hatteras (H) the drifting is, for a similar 

 reason, southwestward. 



Examples of remarkable driftings of beach materials along the Atlantic coast are on 

 record. A vessel, the " Sylph," was wrecked in 1814-1815 on the south side of Long Island, 

 and materials from the wreck were drifted westward beyond Fire Island ; and 7 years 

 afterward her rudder was found 20 miles west of where she was lost. In another case, 

 coal from the cargo of a vessel wrecked on the south side of Nantucket was carried 

 eastward and then northward, and the keeper of the lighthouse of the north cape, called 

 Great Point, supplied himself from it with fuel for the winter ; and brick from another 



