MARYLAND GEOLOGICAL SURVEY 33 



and Ilindoostan. He went farther and divided Maclure's " Alluvial " 

 up into Ferruginous Sand and Plastic Clay. He believed that the Plastic 

 Clay was Tertiary, and based his conclusions on the presence of amber, 

 which he found at Cape Sable, correlating it with the amber 

 of the Baltic. He also assigned to the Plastic Clay certain of the 

 Indian kitchen-middens, which are found along the shore of Chesapeake 

 Bay, thus opening a controversy regarding the age of these interesting 

 deposits of 03^ster shells which did not reach a final settlement until 

 many years later. He believed that the materials composing his Ferru- 

 ginous Sand and Plastic Clay were deposited by a flood from the north 

 or the northwest, agreeing somewhat closely with Hayden in this particu- 

 lar. His correlations were based almost entirely on lithologic distinc- 

 tions, supported by a general similarity of fossil forms. No critical 

 study of the fossils was undertaken, however, and few localities were 

 given and no geologic boundaries whatever. It is consequently impos- 

 sible to ascertain where he intended to place the formations which we 

 now ascribe to the Eocene, Miocene, and Pleistocene periods. One thing, 

 however, he perceived very keenly — that the deposits in southern Mary- 

 land would with future work be separated into many distinct formations. 

 This prophecy has since been fulfilled. During the same year Thomas 

 Say described the collection of fossil shells made by Finch, and among 

 them appeared many forms from Calvert County. This collection is 

 still preserved in the British Museum. 



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, how- 

 ever, 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 Eenssellaer's correlation of the great deposits of 



