Pliocene and Pleistocene
1906, Maryland Geological Survey
Systematic Report, Pliocene & Pleistocene
Part I (a): The Pliocene and Pleistocene deposits of Maryland, Shattuck, G.B.
Part I (b): The interpretation of the paleontological criteria, Clark, W.B., Hollick, A., and Lucas, F.A.
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. Several 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 complete sequence of geological formations representing nearly every horizon from the Archean to the Pleistocene although these vary greatly in thickness 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 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. (from the preface to Pliocene and Pleistocene, p. 17-18)