38 THE PHYSICAT. FEATUKES OF PKIXCE GEOKGE's COUXTY 



1835. 

 Conrad, T. A. Observations on the Eocene Deposits of the United 

 States. Fossil Shells of the Tertiary Formations of ISTorth Americo, 

 vol. i, N'o. 3, pp. 29-36. Phila., 1835. 

 Republish by G. D. Harris, Washington, 1893. 



Describes the distribution of the Eocene of the county mentioning its 

 occurrence at Fort Washington, Piscataway and Upper Marlborough. The 

 latter place the author believed was the northern limit of the Eocene. 



Conrad, T. A. Observations on the Tertiary Strata of the Atlantic 

 Coast. 



Amer. .Jour. Sci., vol. xxviii, pp. 104-111, 280-282. 



He considers the miocene absent in this region, the Older Phiocene resting 

 directly on the Eocene. The beds containing Perna maxilla ta are referred to 

 the Older Phiocene, and the St. Mary's river beds to the Medial Phiocene. 



Conrad, T. A. Observations on a portion of the Atlantic Tertiary 

 Region. 



Trans. Geol. Soc. Penn., vol. I, 1835, pp. 335-341, pi. 13. 



Deposits at Piscataway and Upper Marlborough are described. At the 

 former locality the following new forms are described: Panopea elongata. 

 modiola cretacea, and Turritella humerosa. 



Dugatel. J. T. and Alexander, J. H. Eeport on the J^ew Map 

 of Maryland, 1834. Annapolis, 1835 ( ?). 8vo, 59+1 pp. Two maps 

 and one folded table. Contains Engineer's and Geologist's reports, 

 which were also issued separately. 



Md. House of Delegates, Dec. Sess., 1834. 



In the report of the engineer, Mr. Alexander, a very good account is given 

 of the way in which Piscataway Creek is being filled up with silt. It is 

 recommended that canals be dug along both sides of the stream to receive 

 the wash from the hills and empty it into the Potomac rather than per- 

 mitting it to fill up Piscataway Creek, an expedient perhaps, however, more 

 costly than useful. 



In the geologist's report the Eocene deposits at Fort Washington, Pisca- 

 taway, and Upper Marlborough are described while the value of the shell 

 marls of the region for economic purposes is discussed. He says that no 

 Miocene has yet been recognized in the State. The physiography of the 

 region is described and mention is made of the gravel cap at Fort Washing- 

 ton, though it is not separated from the Eocene. The map contains many 

 notes in regard to the geology of the region bordering the Potomac River. 



