18 PREFACE 



paleontologic records of their history have been only slightly obscured 

 by succeeding events. The deposits of the earlier or Pliocene formation 

 are devoid of organic remains, but the same is not true of the Pleistocene. 

 Not many truly marine species have heretofore been found in the 

 Pleistocene deposits along the Atlantic Coast and few, compared with 

 the abundant faunas of the Eocene and Miocene, have been found in 

 Maryland. The investigations of the Survey during a term of years 

 have brought to light several fossil-bearing localities in which the fauna 

 is marine. Elsewhere within the State terrestrial animals and plants 

 have been found giving a diversified fauna and flora to these deposits. 



The Pliocene and Pleistocene deposits of Maryland have been studied 

 for many years by the author of this paper although very little has been 

 published hitherto regarding the subject. Three folios have been pre- 

 pared for the U. S. Geological Survey by the author and his associates 

 in which the Pliocene and Pleistocene deposits have received extensive 

 treatment. 



Dr. B. L. Miller, who has been associated with Dr. Shattuck for many 

 years in a study of the Pliocene and Pleistocene formations, is the author 

 of the Dover folio and also the associate of Dr. Shattuck in the prepara- 

 tion of the Patuxent and St. Mary's folios and has more recently extended 

 the study of these formations into Virginia and North Carolina. 



The paleontological studies have been conducted by several investi- 

 gators. The Mammalia have been studied by Dr. F. A. Lucas of the 

 Brooklyn Academy of Arts and Sciences; the Eeptilia by Dr. 0. P. Hay 

 of the American Museum of Natural History; the Insecta by Dr. E. H. 

 Sellards of the University of Florida; the Crustacea, Mollusca, Coelen- 

 terata and Protozoa by Dr. William Bullock Clark, State Geologist; the 

 Bryozoa by Dr. E. 0. Ulrich of the U. S. Geological Survey and the 

 Plantae by Dr. Arthur Hollick of the New York Botanical Garden. Mr. 

 Paul Bartsch of the Smithsonian Institution has made a very exhaustive 

 study of the Pyramidellidse from the Maryland Quaternary and Tertiary 

 deposits in connection with his studies of this family and the results of 

 his work have been incorporated not only in the Miocene but in the pres- 

 ent report. 



The State Geological Survey desires to express its thanks for the aid 



