20 PROCEEDINGS OF THE ACADEMY OF [1880. 



ON THE STRATIGRAPHICAL EVIDENCE AFFOKDED BY THE TERTIAEY 

 FOSSILS OF THE PENINSULA OF MARYLAND. 



BY ANGELO HEILPRIN. 



The Tertiary deposits of Maryland have from time to time 

 attracted the attention of investigators more or less eminent in 

 their special lines of research, the results of whose observations, 

 owing to the then imperfect state of American geological and pale- 

 ontological science, only very gradually tended to unfold the true 

 relations existing between the S3'nchronous formations of the 

 east-Atlantic and west-Atlantic countries. 



Maclure, on the map accompanying his " Observations of the 

 Geology of the United States " (1817), classed all the late super- 

 tlcial deposits of Maryland imder the general term " Alluvial," 

 which term was likewise applied to almost the entire border 

 deposits of the Atlantic and Gulf slopes. In 1824 (J. A. N. S., 

 vol. iv) Sa}^ described about forty species of fossil shells collected 

 by Mr. Finch from the' same state, but excepting some passing 

 reflections on the nature of the deposit whence they were obtained, 

 and on the great resemblance existing between some of the forms 

 and forms still living on the coast, no special geological inferences 

 were drawn from the collection. From a comparative examination 

 of the contained fossils. Van Rensselaer (" Lectures on Geology," 

 1825, p. 261) subsequently referred the deposits in question to 

 the Upper Marine formation, which view was concurred in by 

 Morton in a paper read before the Academy of Natural Sciences 

 of Philadelphia in June, 1828. In a previous paper (*' Geological 

 Observations on the Secondary, Tertiar}-, and Alluvial Forma- 

 tions," J. A. N. S., January, 1828), published conjointly by 

 Yanuxem and Morton, no attempt was made to correlate the various 

 divisions of the American and European Tertiary formations. 



Conrad, who, more than any other American geologist, con- 

 tributed to advance our knowledge of the geology and paleon- 

 tology of this latest period, was the first to recognize the existence 

 of at least three distinct post-Secondary^ formations in Maryland, 

 the oldest of which he identified by a series of a few fossils found 

 near Ft. Washington, on the Potomac, as belonging to the Eocene, 

 and the newest, as exposed on the southeast extremity of the 

 peninsula, to the Post-Pliocene (J. A. N. S., vol. vi, and Bulletin 



