﻿126 GEOLOGICAL ACTION OF 



and it is a curious illustration of it that lobsters are now found at the breakwater in 

 Delaware Bay, where none existed before, the eddying tides having in the few years 

 that have elapsed since its construction deposited a material suited to their support.* 

 That such deposits are partly above and partly below the water does not impair the 

 efficiency of the cause by which they are produced. They are seen both above and 

 below in the sandy formations of the New England coast, the submerged and exposed 

 positions being continuous and forming a link between islands and shoals. 



To return to the general statement : the currents, being interrupted in their course 

 in passing prominent points, are easily deprived of their freights by any unevenness in 

 the ground over which they move. This is so common, that, at every point and head- 

 land around which the tides turn, there is a shoal of greater or less extent joined to the 

 land, and making a continuation of the beach. When the site is liable to the destructive 

 violence of storms, the shoal will be small, shifting, and irregular. In the case of those 

 points and capes already cited, which inclose bays, a protection is afforded to the eddies 

 themselves and to the deposits made by them, that leads to certain and continuous in- 

 crease. 



Other circumstances may combine to produce the most favorable conditions under 

 which the hook deposit can be made. If a current freighted with suspended matter 

 has passed in its course over a bottom of regular and unbroken slope, it will, on reaching 

 the point, have parted with but little of its burden. But the current, released from the 

 restraint of the shore against which it presses, commences to turn inward at the place 

 where the eddies created by the point arise, and then the most advantageous conditions 

 of construction will cooperate, and the result will be a tongue or spit of curvilinear 

 shape; that is, a perfect hook. This is the manner in which those bays or bights, more 

 or less protected, which are seen on the inner side of each one of the sandy capes, are 

 formed. The accumulation of material is in some cases so rapid as to be easily estimat- 

 ed from time to time. The hook, lengthened by successive additions, and brought to 

 the surface by the tidal deposit, owes its gradual elevation above the water to the action 

 of the winds. They transport materials from the opposite shores, and also drive up the 

 sand that is left dry by the receding tide. These secondary points are sheltered from 

 the destructive action of the waves by their primaries, and on the inner side of the 

 former the protection is still more secure. 



The new point of the hook gives rise to its own eddies, the effect of which is finally 



* The process of " warping," as practised on the banks of the Hutnber, exhibits the working in a similar 

 manner of this principle of deposit. — See Mr. Colman's Agricultural Report, Part VI. 



