ON THE ACTION OF CURRENTS. 451 



result from the momentary action of a predominating 

 wind ; but this action, although already limited to the 

 mobile matters which form the bottom of the sea only in 

 some parts, whether this action, I say, extends to a great 

 depth, that is to several hundred yards, is a question 

 not yet resolved. In the first place, the observation 

 made by mariners, that, in the most violent tempests, 

 the sea is only agitated towards the coasts, or on shal- 

 lows, and that bodies, sunk to a great depth, (and still 

 what is this depth in comparison with that of the sea,) 

 do not feel the motions of its surface, nor that of cur- 

 rents ; and, secondly, reasoning, and even calculation, 

 according to Messieurs La Place and Poisson, concur to 

 shew, that the violent motions of the waters of the sea 

 are not propagated to a great depth. It is therefore 

 probable, that all the transportable matters, which are at 

 this depth, must remain nearly in the position in which 

 they are, since our Continents have assumed their pre- 

 sent configuration, unless phenomena and motions of the 

 sea take place at the bottom, of which we are* ignorant, and 

 which are foreign to the subject which at present occu- 

 pies our attention. 



But if we have no perfectly certain ideas regarding 

 the propagation of the motions of the sea in depth, we 

 can assert, that, whatever that extent and that power 

 may be, the submarine currents no more abrade the 

 rocks than rivers do the surface of the land. This proof 

 is always derived from the "same kind of fact, name- 

 ly, from the vegetable and animal bodies which constant- 

 ly cover the rocks, and which are found, at all times, by 

 means of various sorts of dredge-fishing. In fact, no one 

 has remarked, that the places in which oysters, mussels, 



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