348 On the supposed transportation of Rocks. 



Art. X. — On the supposed transportation of Rocks ; by 

 J. E. De Kay. 



Communicated to the New York Lyceum of Natural History. 



Mr. Hayden, in his truly valuable and original essays on 

 geology, alluding to the large masses of rock scattered over 

 the country, coincides with the chief modern geologists, in 

 supposing that they have been transported to these places, by 

 means of torrents and ice. Indeed one of the strongest 

 points in his peculiar geological views, is based upon this sup- 

 position, for he not only adopts it to its fullest extent, but by 

 a careful and patient investigation of the surrounding coun- 

 try, endeavors to show the precise locality from whence these 

 detached masses originally came. In almost every instance 

 we believe, he has shown that these bowlders are situated in a 

 direction uniformly south west from the spot, where he sup- 

 poses them originally to have belonged. These considera- 

 tions give deservedly great weight to his theory, of a powerful 

 current having at one time swept over the whole continent of 

 America, in a north east and south west direction.* 



Without calling in the aid of ice, or torrents, or volcanos 

 or the extravagant hypothesis of Chabrier,! that these isola- 

 ted rock-masses have fallen from the atmosphere, we suppose 

 that their appearance may sometimes be accounted for in a 

 different manner. A fact recently communicated to the Ly- 

 ceum, suggested the idea. 



It is well known that all the southern part of the island of 

 New York, is composed of gneiss covered with sand. Pro- 

 miscuously scattered over the surface and imbedded in the 

 sand, are bowlders of different sizes, up to several tons in 

 weight. They are totally unlike any rocks, in place, in the 

 immediate vicinity, being chiefly greenstone or trap, occasion- 

 ally slaty, sometimes granitic and not unfrequently calcare- 

 ous, containing organic remains. 



Agreeably to the ideas generally entertained by geologists, 

 Dr. AkerlyJ has referred the schistose rocks to the region 

 above the Highlands, the greenstone to the pallisado rocks 



* Geological Essays ; or an Enquiry into some of the geological phenomena 

 to he found in America and elsewhere. — Baltimore 1820. 

 f Dissertation sur le deluge universel. — Montpelier 1823. 

 % Essay on the Geology of the Hudson river &c. — New York 1820, 



