﻿THE CURRENTS OF THE OCEAN. 127 



to deposit on the inside, and near the extremity, a level plateau or flat of sand, as might 

 be expected from the sluggish character of the derivative undulations, which here will 

 have nearly reached a state of quiescence. 



If the cape projects far into the sea, like Cape Cod, and incloses a deep bay, a 

 large body of the current which turns to enter the bay at its extremity will pass the first 

 hook and carry the flood towards the lower shores, and thus a new hook may be formed. 

 But as it will not often happen that the circumstances in the second case are' the same 

 as those in the first, so the two constructions will differ in outline. One will be complete, 

 like the Bay of Provincetown, and the other a shoal or bank interspersed with islands, 

 like the second formation at Wellfleet Bay. Each one of the capes, Sandy Hook, Cape 

 Poge, Great Point, and Cape Cod, are illustrations, more or less complete, of the hook 

 structure. 



We know something of the gradual growth of two of them from early surveys. It 

 appears from a survey made in 1778, that at that date the northern limit of the point of 

 Sandy Hook was about fifteen hundred feet from the old stone light-house. It has 

 since then extended more than three thousand feet to the north and east. In 1778 the 

 main ship-channel ran much nearer the light-house. But at the time of the discovery 

 and settlement we must carry the extreme limit much farther south, bringing it nearer to 

 Horseshoe Bay, where the form from which the name is derived would have been 

 more exactly preserved. Since the preceding date we are able to trace, by surveys made 

 from time to time, the manner and amount of alteration. The point has advanced to 

 the north, spreading out to the east, and losing somewhat of its hook form, owing, no 

 doubt, to the effect of an interruption to the tidal current on the outside, causing there a 

 local excess in the deposit. 



Plate III. exhibits the changes in Sandy Hook between 1778 and 1844. Plate II. 

 is a copy of a chart of Cape Cod, by Des Barres, in 1764, from the library of the Uni- 

 versity at Cambridge. The inner part of the hook is there represented as a shoal. A 

 still more surprising example of increase occurs in the belt called Nausett Beach, which 

 incloses the harbour of Chatham. Captain Franklin Nickerson of Chatham informs me 

 that when he first went to sea, twenty years ago, the common channel-way into Chat- 

 ham harbour was two miles north of the present opening. The beach-grass is now 

 growing on the site of the old channel. His father, he adds, who died about one year 

 since, remembered when the channel-way was still farther north. The present inclosed 

 basin was then an open harbour, and the inclosure has been made by the gradual exten- 

 sion of the belt to the south. 



Great Point (Nantucket) furnishes a striking instance of external deposit. A long 



