XXXVl GEOLOGICAL AND PALEONTOLOGICAL RELATIONS 



In the year 1825 J. Van Eenssellaer assigned the deposits of the 

 Coastal Plain to the Tertiary, and divided them into Plastic Clay, 

 London Clay and Upper Marine. He further correlated the deposits 

 of Maryland which we now know as Miocene with the^ Upper Marine of 

 Europe and probably in part with the London Clay. It should be 

 noted here, however, that Finch had previously used Upper Marine in 

 a different sense. He had applied it to the sand dune formations of 

 Cape Henry and Staten Island, while Van Renssellaer adopted it for a 

 true fossiliferous formation of very much greater age than the deposits 

 which Finch had embraced under the same name. Three years later, 

 in 1828, Morton, although accepting Van Renssellaer's correlation of 

 the great deposits of 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 Alluvial 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. He mentioned St. Mary's county particu- 

 larly as being one of the Tertiary localities, and he also pointed out 

 some of the differences between the faunas of the Secondary and 

 Tertiary formations. 



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 could be found. Two years later Conrad pub- 

 lished 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 



