﻿142 GEOLOGICAL ACTION OF 



constitute the tides, as they are spoken of in popular language, and known to the com- 

 mon observer. But the retarding influence will first be felt at the outer bank, or line of 

 soundings, that marks the approach to the coast of the United States, and the result will 

 be an early diversion of the tide-wave from its regular course, altogether independent of 

 the local peculiarities occasioned by its subsequent collision with the diversities of the 

 shore itself. 



As the tide-wave, then, advances along the eastern border of this continent, it will be 

 deflected to the east by the obstacles it encounters in its progress towards the coast of 

 New England and the British possessions, until, passing the eastern limit of opposition at 

 Newfoundland, its regular course is resumed. This statement is partially made in the first 

 section of this memoir, where the conformation of the Nantucket Shoals is described, and 

 their relation to the tidal currents defined. The Nantucket Shoals, being formed in the 

 sea, have a closer affinity to the great banks than the hooks or bay-deposits, which are due 

 to tidal currents that are specifically local. By enlarging the bounds of the reasoning 

 applied to the former, we should expect to find those great sand deposits, George's, 

 Sable Island, Banquereau, Green, Whale, and Newfoundland Banks, in the very positions 

 they occupy, that is, in the path of the general tide-wave that washes the shores of the 

 continent, modified as it is by the obstacles to its regular course. 



It has already been assumed, that there is probably a nucleus which determines the 

 precise locality of a subaqueous deposit, and that its amount and form depend upon the 

 condition of the water as to motion or rest when it takes place. But I will also venture 

 to suggest, that further investigations into the tidal currents of this part of the ocean 

 may disclose a meeting of the tides at each of the two great banks of George and New- 

 foundland, perhaps from the confluence of the regular tide-wave of the Atlantic with the 

 divergent wave from the American coast, the two waves belonging of course to different 

 epochs. This view is supported by the motions of the tidal currents. They go entirely 

 round the compass in every successive ebb and flood at both of these places. On 

 George's Bank, according to the excellent survey of Captain Wilkes, the main body 

 of the flood sets to the northward and westward, and changes from that to the eastward 

 of north; and this change may be caused by a conflicting current from the coast. The 

 prevailing opinion that there is a southerly and westerly current along the east and south 

 coasts of Newfoundland indicates, in connection with the circular motion of the tidal 

 currents on the Grand Bank, that a similar conflict may exist here also. On the southern 

 coast of Nova Scotia, the establishments between Cape Sable and Cape Canso vary 

 about one hour in time, being most early at the west. From this it appears that the 

 tide-wave approaches this coast at right angles to its line of direction. 



