( 439 ) 



No. LXVIII. 



Memoir on the Sand-lil/s of Cape Henry in Virgi/iiu, 

 By B. Henry Latrobe, Engineer. 



December igf/j, 1798. 



Read, Dec. T?ROM the falls of tlic great rivers of Virginia 

 21, 1798- Jj over the out-runnings of the granite (Irata, the 

 general level of the land gradually approaches the level of 

 the ocean. At the falls it is elevated from 150 to 200 feet 

 above the tide : on the fea Ihore at Cape Henry, the ori- 

 ginal coaft rifes not more than 1 5 feet above high v^'ater 

 mark. 



That the whole of this extenfive country, from the falls 

 tothecoaft, is faftitious, and of Neptunian origin, appears 

 far from being hypothetical ; and the foflil teeth and bones, 

 which accompany this memoir,* and which with many 

 hundred more, were dug out of a well at Richmond, from 

 the depth of 71 feet, prove that the depofitlon of the fu- 

 perilrata is not of a date fufficiently removed to have de- 

 ftroyed the foft and almoft cardlaglnous part of the joints, 



or 



* The teelli appear to be tliofe of a fliark. They arc highly enamelled and 

 extremely fharp : their roots are perfcflly fcund and entire, and die minute 

 and almoft tranfparent jags of many of them are as perfeft as the reft. They 

 are found in every well, dug in or near Richmond, to a fufficient depth ; and, 

 as I am informed, in every deep well for many miles belov\' the city. The 

 ftratum in which they lie con'.ifts of highly fulnhurated blue clay, abounding 

 in pyrites, and which has the appearance of having been mud. They were 

 firft difcovered in the beds of rivulets, which had \vorn their channels to the 

 depth of this ftratum ; and obtained tlie natne of Indian Dart-points, in the 

 fame manner, as die immcnfe oyfterbeds, which li^ve been quitted by die 

 ocean, are vulgarly called Indian oyfter-banks. 



The bones were dug from the feme ftratum. Among them are two out of 

 fix bones, which formed a. pa'w of feme animal unknown to me. Many very 

 fotind vertcbros of fifti. and a remarkably perfeift thigh bone of a large bird 

 3iave been in my pofTeftion. 



