XVI PREFACE 



and floras. Three of them, the Carboniferous-Permian, the Jurassic- 

 Cretaceons, and the Pliocene-Pleistocene, contain both animal and plant 

 fossils in abundance. The Ordovician-Cambrian, the Silurian, the 

 Devonian, the Eocene, and the Miocene all contain extensive faunas 

 while few if an}' plant remains are known. 



These reports when completed will give both to the geologist and to the 

 general reader a comprehensive view of the past history of Maryland 

 territory from the earliest geological period to the present day. They 

 will be by far the most important publications of the Geological Survey 

 and will have not only present but lasting value to the student of Mary- 

 land geology. Long after the general articles and county reports will 

 have become antiquated they will be useful, and must necessarily afford 

 the basis for all subsequent study of Maryland geology. The present 

 volume on the Miocene deals with the middle period of the Cenozoic, and 

 with the Eocene which precedes and the Pliocene which succeeds it 

 embraces what is frequently denominated by geologists as the Tertiary, 

 one of the most important geological horizons represented in Maryland. 

 The Miocene deposits of Maryland have been studied since the early 

 days of American geology. Fifteen years ago they attracted the attention 

 of the senior author of this report under whose direction Dr. Shattuck has 

 carried out the elaborate stratigraphic studies described in later pages. 

 These investigations have been in progress since the organization of the 

 Survey and large collections of fossils were made both from the historic 

 as well as from new localities. Dr. Shattuck has had in his work the 

 active cooperation of all the members of the Survey, including especially 

 that of the State Geologist, and of Dr. L. C. Glenn and Dr. G. C. Martin, 

 who frequently visited the field to discuss obscure points with the author, 

 while their paleontological studies were carried on in such a way that the 

 results here presented represent the combined labors of the field geologist 

 with the critical laboratory study of the paleontologist. 



An important paper by Dr. W. H. Dall accompanies this report in 



