366 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 28, 



grains of dark sand, white quartz, and fragments of slate which pre- 

 vail in the neighbourhood of Port Patrick, are probably the lowest 

 exhibited. 



2. On the Action q/ Ocean-currents in the Formation of the 

 Strata of the Earth. By C. Babbage, Esq., F.R.S. 



[Communicated by W. H, Fitton, M.D., F.R.S., F.G.S.] 

 (Abstract.) 



In the year 1834 the author communicated to the Society a paper 

 on the Temple of Serapis, at Puzzuoli, near Naples, in the concluding 

 portion of which paper* he suggested an explanation of the fact that 

 certain portions of the earth's surface are subject to periodical alter- 

 nations of elevation and depression, extending through vast periods 

 of time : and the extreme slowness with which certain very fine powders 

 of a heavy substance (emery) subside in water, suggested to the 

 author the vast extent to which very finely divided matter suspended 

 by the Gulf Stream might be spread over the bottom of the Atlantic, 

 — a subject alluded to by him in 1832 in the * Economy of Manu- 

 factures f-' 



Some years afterwards, looking for better explanations of the phse- 

 nomena of outliers and the folding and inversion of strata than he 

 had hitherto met with, Mr. Babbage reverted to the consideration of 

 sedimentary deposition. Hence the origin of the present communi- 

 cation. 



In the first part of this paper the author traced out the laws 

 which regulate the distribution of very finely divided earthy matter, 

 borne outwards from river-mouths and sea-cliffs into the ocean-cur- 

 rents, over extensive areas. The time that a particle of matter 

 requires to fall through a given distance in a resisting medium 

 depends — 



1st. On the specific gravity of the particle itself. 



2nd. On its greater or less magnitude. 



3rd. On its form. 



4th. On the law of the resistance of the medium through which 

 it falls. 



These several points were treated of by the author, who then pro- 

 ceeded to show under what conditions certain finely triturated sub- 

 stances, of given size and composition, suspended in a current of a 

 given velocity, would be deposited in a sea of a given depth. 



Supposing a river to send out, suspended in its water, particles of 

 triturated limestone, of different degrees of fineness, and the river at 

 its junction with the sea to be 100 feet deep, and the sea to have a 

 uniform depth of 1000 feet over a great extent, the different results 

 in the deposition of the several varieties of the suspended particles 



* Proc. Geol. Soc. vol. ii. p. 75 ; and Quart. Journ. Geol. Soc. vol. iii. p. 206, &c. 

 t Art. 63, 4th edit. 



