MARYLAND GEOLOGICAL SURVEY 39 



Martin. Joseph. A Comprehensive Description of Virginia, and 

 the District of Columbia. Eichmond, 1835 ( ?). 



He describes the separation of the "Primitive" and "Alluvial" formations 

 in the District. In the former gneiss abounds and is succeeded by "amphi- 

 bolic" rock. 



Morton, S. G. Additional ObseiTations (to Synopsis). Svo, 4 pp. 

 Phila., June, 1835. 



Gryphaea vomer is added to the Eocene forms obtained at Upper Marl- 

 borough and Piscataway. 



1836. 

 DucATEL, J. T. and Alexander. J. H. Keport on the New Map 

 of Maryland, 1835. 8vo, 84 pp. Maps. Annapolis, 1836. 



Md. Pub. Doc, Dec. Sess., 1835. 



Engineer's Report, pp. 1-34, Geologist's Report, pp. 35-84. 



Both reports also published separately. 



In the engineer's report a good description of Piscataway Creek is given 

 and the changes which are taking place in it. A plan for a canal extending 

 up the creek to the town of Piscataway is discussed. 



Ducatel reports the presence of a micaceous black sand in the deep ravines 

 bordering the Mattaponi in the vicinity of Nottingham. It is said to form a 

 part of the "ferruginous sand formation" which he believes to belong to the 

 Secondary Analyses of micaceous black sand, green sand period (1-83) and 

 shell marl (p. 82) are given. 



Featherstoniiaugk, G. W. Keport of a Geological Reconnais- 

 sance made in 1835 from the seat of government by way of Green 

 Bay and the Wisconsin Territory on the Coteau du Prairie, an 

 elevated ridge dividing the Missouri from the St. Peters river. 



169 pp., 4 pis., Washington, 1836. 



Describes the decomposed gneiss above Georgetown and along Rock Creek. 

 He says that the gneiss underlies Washington and Georgetown dipping to the 

 southeast. 



1837. 

 Ducatel, J. T. and Alexander, J. II. Report on the New Map 

 of Maryland, 1836. 8vo, 104 pp., 5 maps. Annapolis, 1837. 



Md. House of Delegates, Dec. Sess., 1836. 



Geologist's Report, pp. 1-60, Engineer's Report, pp. 61-104. 



Ducatel describes shell and greensand deposits of Eocene and Miocene age 

 from many places in the county and discusses their economic value as 

 fertilizers. He mentions the pink clay (Marlboro) occurring with green- 

 sand north of Upper Marlborough. 



