MARYLAND GEOLOGICAL SURVEY XXXvii 



and made it equivalent to the Upper Tertiary of Europe. The follow- 

 ing year John Finch published another book on his travels in Mary- 

 land which had been made almost a decade before. In this narrative, 

 Finch gives a most interesting account of the great delight which he 

 experienced in collecting from the enormous deposits of fossil shells 

 in St. Mary's county. The same year Morton published another paper 

 in which he proposed 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. 

 During the same year also Isaac Lea described some fossils from the 

 St. Mary's river and regarded them as older Pleiocene. He, too, doubted 

 the existence of the Miocene in Maryland. The next paper of import- 

 ance was published by Conrad, in 1835, in which he assigned the Mio- 

 cene deposits to the older Medial Pleiocene. In the following year 

 Ducatel referred the deposits of St. Mary's and Calvert counties to 

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

 also published a map of southern Marjdand in which various deposits 

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



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

 posits in Maryland. He made the announcement in 1836 that part of 

 the Maryland Tertiary belonged to the Miocene. The following year 

 Ducatel agreed that if the deposits of Upper Marlboro and Fort Wash- 

 ington were Eocene then the blue marl of Charles county was Miocene. 

 This view, he said, he had formerly entertained but had afterward 

 abandoned it. During the next year Conrad ascribed formations to 

 the Medial Tertiary and correlated them with the Crag of England. 

 He noted the great difference between the fossil and living species, 

 showing that the Medial Tertiary contained but 19 per cent, of living 

 species. He thought that the extermination was due to a fall of 

 temperature. In the same and the following years he described many 

 fossils from the Miocene of Maryland and in 1812 he correlated his 

 Medial Tertiary with the Crag of England and stated it was Miocene. 

 The boundaries which he gave the Miocene at that time were not 

 greatly different from the boundaries which are ascribed to the Chesa- 

 peake Group of to-day. In 1844 Bailey described some ten species of 



