4 THE LAW OF DEPOSIT VI. 



from Florida to Maine, regarded as a whole ; to the gigantic subaqueous accumula- 

 tions to the North and East, as George's Bank, Newfoundland Bank, &c., to the Bay 

 of Campeachy, and the shores of the Gulf of Mexico on the West and the North, to the 

 belt of sand on the west coast of Peru, which on the North terminates in the Desert 

 of Pachira ; and passing from America to Europe, to that most interesting of all 

 similar formations, the countries of the Netherlands, which owe their national pecu- 

 liarities to the character of their territory, to the sandy region on the southern 

 border of Norway ; and, finally, to the well-known Landes of France. 



In that part of the investigation which relates to our own coast, and which com- 

 prised the introduction of the elementary principles of this theory, the tidal currents 

 referred to owed their origin to purely local causes, and were restricted to limited 

 areas. But in the section devoted to the subject of " Geographical Distribution," 

 the o-eneral course of the tidal wave, and the points of divergence and convergence 

 were treated ; currents, the influence of which was felt through large spaces, were 

 considered ; peculiar systems of waves, the resulting motions of the water occasioned 

 by the conflict and mutual interference of waves approaching each other in different 

 directions, as in the English Channel, and round the Island of Great Britain in the 

 North Sea, or round Ireland in St. George's Channel and the Irish Sea, were men- 

 tioned ; and lastly, two conspicuous examples were brought forward of the similar 

 action of permanent ocean currents, where they impinged with one continuous 

 direction on a long line of coast on the sea border of Peru, and on the shores of the 

 Gulf of Mexico. 



The concluding section of this Memoir was reserved for an inquiry into the 

 geological action of the tides in the past ages of the earth's history. The instances 

 were taken from the tertiary and subsequent periods ; and in the cases cited there 

 was no difficulty in determining how the transmission of the tide wave, and conse- 

 quently the character of the currents during the accumulation of the aqueous 

 deposits in question, had been affected and controlled by the earlier formations. 



The geographical distribution of the Dune, or alluvial Flora, on the shores of the 

 United States, and of Nova Scotia, was employed, at the suggestion of Professor A. 

 Gray, of Harvard University, to throw additional light upon this theory ; a striking 

 and instructive resemblance was noticed between the bottoms of our principal bays 

 in their present state, and the formation and condition of the valleys in the Swiss 

 Canton Soleure, as described by M. Gressly; and, by means of a somewhat 

 minute description of Nantucket Shoals, and the intervening channels, with their 

 inhabitants, it was attempted to show that, throughout all periods of geology, one 

 of the grand results of the operation of the tidal laws had been to prepare the place 

 suitable to marine animal life. 



The preceding is a very brief and general sketch of the theory and its applica- 

 tions, contained in the Memoir mentioned at the beginning of this paper. It is 

 introduced here to give interest to what follows, and to exhibit its connection. 



In the section relating to geographical distribution, it was laid down as a funda- 

 mental principle, that the deposits on the ocean horder are only made by the current 

 of the flood tide. It was added, by way of explanation, that, " in the sounds and 

 s, the ehh tide may also leave its burden; since, in its retreat, it may not only 



