﻿THE CURRENTS OF THE OCEAN; 153 



or alluvial flora of North Carolina is repeated, as he informs me, on the shores of New 

 Jersey, of Long Island, and the southern and eastern coast of New England. Follow- 

 ing the course of the tide-wave, these Southern plants are found at Plymouth (opposite 

 Cape Cod), where there is a large bay deposit, and to the north of Cape Ann, in the 

 bight formed by the projection of this cape, where also occurs another instance of bay 

 deposit, at Ipswich, and Newburyport. Lastly, a few of these plants are found on the 

 south coast of Nova Scotia. How far this reasoning may be thought to explain the 

 existence of the same flora in the adjacent countries, situated on opposite sides of the 

 same channel, and washed by tidal streams which, acting upon a system of rotation, 

 have carried the same materials in succession to the shores of each, through the long 

 ages of the past, is hereafter to be considered. A similar result will also be produced 

 in two countries far remote from each other by the transmission of a tidal undulation 

 which, leaving a bold and projecting coast, arrives, without intermediate interruption, 

 at some distant point or island. 



Having already dwelt longer than was intended upon this part of the subject, I will 

 only make a hasty reference to the utility of this theory of the geological action of the 

 tides in accounting for the great sand deserts, as it has been applied (in Sect. III.) to 

 explain the Peruvian sand desert of Pachira. 



The interposition of a continent (or chain of islands) occupying a great extent of 

 latitude in the path of the elementary tide-waves, as is the case with Africa, may be 

 supposed to offer the most favorable conditions for immense sand deposits exceeding all 

 others in-amount. Here the tidal currents would be employed, not only in distributing 

 and collecting the detritus of the African mountains, but also in transporting a part of 

 that of the Eastern continent and islands. The extent of the sand deserts, so charac- 

 teristic of this part of the globe, is to be attributed mainly to the wide spaces between 

 the higher grounds, or earlier formations, in which the various forms of deposit have 

 been often repeated on a grand scale. These, however, and other geological details, are 

 designedly left, on account of their number and diversity, to a future and not distant 

 occasion. 



But there is no point of view from which the geological action of the tides appears 

 more interesting than in its connection with the geographical distribution of marine 

 animals. It is well known to the zoologist that the sea is the principal seat of animal 

 life, and that it is near the land, and not in the distant depths of the ocean, that this 

 life is displayed in the greatest amount and variety. It will be found upon inquiry that 

 marine animal life is most abundant and most useful to man on the shoal formations. In 

 this region are the great fishing stations, and, as fishes are predatory in their habits, 



