34 THE PHYSICAL FEATURES OF CALVERT COUNTY 



fossil shells in the Maryland Coastal Plain with the Upper Marine of 

 Europe, apparently used the term in a much wider sense than its author 

 had employed. He also gave a list of the fossil forms occurring in the 

 Upper Marine, and included some which have since been shown to be 

 later than Miocene. During the same year Vanuxem divided the Allu- 

 vial and Tertiary of the Atlantic Coast into Secondary, Tertiary, and 

 Ancient and Modern Alluvial. In this classification the Miocene of 

 southern Maryland was included in a part of the Tertiary. He stated 

 further that vast numbers of " Littoral " shells occurred in the Tertiary 

 analogous to those of the Tertiary of the Paris and English basins. 



Conrad brought out his first publications bearing on the Miocene 

 geology of Maryland in 1830. He agreed with Vanuxem in placing 

 southern Maryland in the Tertiary and pointed out a number of locali- 

 ties where fossil shells were found. Two years later Conrad published 

 another paper in which he divided up the Coastal Plain deposits into six 

 formations. This was the first time that the Coastal Plain had been 

 classified so as to show its extreme complexity, and from this time on 

 it has been dealt with, not as a deposit containing a few formations but 

 as a series of deposits complex in composition and age. Conrad at this 

 time ascribed the Miocene of Maryland to the Upper Marine and made 

 it equivalent to the Upper Tertiary of Europe. 



The following year Morton published another paper in which he pro- 

 posed a classification of the Coastal Plain deposits. In this no distinct 

 reference was made to Maryland, but it is probable that he still regarded 

 the Miocene of this State as Upper Marine. 



The next paper of importance was published by Conrad, in 1835, in 

 which he assigned the Miocene deposits to the older Medial Pleiocene. 

 In the following year Ducatel referred the deposits of Calvert County 

 to older Pleiocene and distinctly stated that they were not Miocene. He 

 also published a map of southern Maryland in which various deposits 

 were marked and the names of the formations given in red letters. 



W. B. Eogers was the first to recognize the presence of Miocene de- 

 posits in southern Maryland. He made the announcement in 1836 that 

 part of tlie Maryland Tertiary belonging to the Miocene. He 



