Mr. La Trobe, in a communication to the American 

 Philosophical Society, seems to intimate that the allu- 

 vial district is produced in part, at least, by the sea ; 

 for he observes that " The shore, and the bed of the 

 Atlantic near the shore, consist of fine sand. The 

 daily action of the flood tide, carries a certain quan- 

 tity of this sand above high water mark, which, being 

 dried by the sun and air, is carried further inland by 

 the winds." 



Mr. La Trobe in this instance, is only speaking of 

 the " sand hills" at Cape Henry in Virginia ; but 

 that he entertains an opinion that nearly the whole 

 was produced in a similar way, we have reason to be- 

 lieve from the following remarks in a note in the 

 same memoir, viz. I speak only of the coast of 

 Virginia, at Cape Henry ; for although 1 have the 

 best reason to believe that the same natural process has 

 produced all the sand banks, islands, and sand hills 

 from the Delaware to Florida, I have only examined 

 that part of the coast which is the subject of the 

 present memoir."* 



While I entertain a high respect for the opinions 

 and talents of Mr. La Trobe, I must beg leave to 

 observe, that although " the shore and the bed of 

 the Atlantic near the shore" may consist of fine sand, 

 it is well known that at a little distance, and from that 

 to a great distance from the shore, at least within 

 soundings, the bottom, or bed of the ocean is com- 



* Philosophical Transactions, vol. 4, page 459. 



