MARYLAND GEOLOGICAL SURVEY XXV 



tic Slope. The fuller discussions will be found in other volumes of 

 the Survey dealing with these formations. 



When we come to consider that assemblage of deposits early sepa- 

 rated as the Tertiary, portions of which are the special subject of this 

 report, we find that it is divisible into several distinct formations. Even 

 at a relatively early date an older and a younger Tertiary were already 

 established, the former being correlated with the Eocene of England 

 and the European continent, and the latter somewhat later with the 

 Miocene or Pliocene. Attempts were made then and later to find their 

 exact equivalents in one or another of the already established local for- 

 mations of the English or Continental series, but with very unsatisfac- 

 tory results. 



Even after the American Tertiary strata had received somewhat de- 

 tailed examination in the various sections of our own country and local 

 divisions had been established, attempts were made from time to time 

 to determine their equivalency. By common consent the diversified 

 and extensive deposits of the Gulf area came to be regarded as the type 

 for the Eocene and the various Eocene deposits of the Atlantic Coast 

 States were assigned to positions in this series. On the other hand, 

 the great development of later Tertiary deposits, which we now know 

 to be largely Miocene, in Maryland and the States immediately to the 

 south of it, led geologists to regard them as the most typical for the 

 Atlantic province and many terms derived from this district have found 

 a permanent usage in geological literature. 



The Miocene deposits of Maryland have long been known to geolo- 

 gists for the rich faunas which they contain and great collections of 

 this material have for many years enriched the museums both of this 

 and foreign lands. The exhaustive studies which have been given to 

 the forms found in these deposits must necessarily prove of great inter- 

 est and value to geologists and paleontologists everywhere. 



The description of species of fossils is of little scientific importance 

 to the geologist, however, unless the object is something other than 

 the mere multiplication of new forms, which has too often been the 

 case in such investigations. When the work has in view the fullest 

 possible representation of a fauna or the clearing up of doubtful points 

 in the synonymy of already described species, as well as a more complete 



