28 THE EOCENE DEPOSITS OF MAEYLAND 



" Catalogue of the fossil shells of the Tertiary formations of the United 

 States," in which many of the. Middle Atlantic Slope forms are included. 



During the year 1835 several important contributions were made to 

 the geology of the Atlantic Tertiary region. Conrad published his in- 

 vestigations upon the Maryland- Virginia Tertiary area, including the 

 description of two new species of Eocene fossils. Rogers presented 

 " Further observations on the greensand and calcareous marl of Vir- 

 ginia," in which the lithological similarity of the beds to the greensand 

 deposits of New Jersey is dwelt upon, altliough he believes that the 

 character of the organic remains shows the strata to be Eocene. Jointly 

 with his brother, H. D. Rogers, he presented to the Philadelphia Acad- 

 emy of Natural Sciences the first portion of " Contributions to the geol- 

 ogy of the Tertiary formations of Virginia," in which several new 

 species of Eocene fossils are described. 



While the investigations hitherto mentioned were being carried on 

 privately, the three states constituting that portion of the Middle At- 

 lantic Slope now under consideration, viz., Delaware, Maryland, and 

 Virginia, became aroused to the importance of official geological surveys 

 of their areas. 



The first to organize such a survey was Maryland, in 1833, J. T. 

 Ducatel being appointed State Geologist. Reports were published until 

 1841, but the information they contain is economic rather than strati- 

 graphic. 



The Geological Survey of Virginia began operations in 1835, under 

 William B. Rogers as State Geologist, who was thus able to continue 

 much more systematically than hitherto his observations upon the Ter- 

 tiary belt. The first report, for 1835, which contains a general state- 

 ment regarding the " Eocene marl district," and most of the subsequent 

 annual reports, which were continued until 1841, include more or less 

 detailed descriptions of the Eocene deposits. Collectively they form 

 the chief source of information regarding the Eocene stratigraphy of 

 Virginia. 



The Geological Survey of Delaware was short lived. Its investiga- 

 tions, under the direction of I. C. Booth, State Geologist, extended only 

 over the seasons 1837 and 1838, for wliich years annual reports were 



