PREFACE 



The present volume is the third of a series of reports dealing with 

 the systematic geology and paleontology of Maryland. The first and 

 second volumes of the series were devoted to discussions of the Eocene 

 and Miocene deposits while the present volume comprises a discussion 

 of the next younger geological formations known as the Pliocene and 

 Pleistocene. The publication of this report will complete the geological 

 history of the youngest of the major divisions of geologic time, the 

 Cenozoic, extending from the end of the Cretaceous to the present. Sev- 

 eral other reports on the systematic geology of the State are well under 

 way. It is not the intention to issue these volumes in geologic sequence 

 but according to the progress of the work. Each volume is a unit in 

 itself and represents a monographic study of a portion of the geological 

 column as it is developed in Maryland. 



Maryland, considering its limited area, contains a remarkably com- 

 plete sequence of geological formations representing nearly every horizon 

 from the Archean to the Pleistocene although these vary greatly in thick- 

 ness and in the completeness of the faunas and floras which they contain. 

 Moreover, the situation of Maryland, extending from the low-lying 

 Eastern Shore to the Continental divide in Garrett county, makes any 

 study of its geological conditions a means of assistance to students in 

 contiguous States along the Atlantic Coast. 



These reports when completed will give to the geologist and general 

 reader a comprehensive view of the geological vicissitudes through which 

 Maryland has passed from the earliest geological period to the present, 

 and to the scientific investigator in nearby areas a reference or classic 

 locality in which the general problems have been worked out. 



The Pliocene and Pleistocene formations, to the elucidation of which 



the volume is devoted, have had a potent influence in determining the 



surface configurations and soils of Maryland. They are the youngest 



formations usually considered by geologists and the physiographic and 



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