Reports
Eocene stratigraphy and foraminifera of the Aquia Formation
1948, Shifflett, E.
Bulletin 3
Purpose and Scope of the Report
The age of the Eocene Formations of Maryland and Virginia in the outcrop has been referred to the Wilcox and Claiborne, Eocene, of the Gulf Coastal Plain on the basis of both megafossils (Cooke, Garnder and Woodring, 1943) and microfossils (Cushman, 1944b, p. 17). No beds of Wilcox age and no beds of definite Claiborne age were recognized, however, by Cushman, on the basis of foraminiferal studies, in the Ohio Oil Company’s Larry G. Hammond well near Salisbury, Maryland, some 50 to 60 miles southeast of the outcrop of the Eocene which trends northeast-southwest across Maryland. Strata of Paleocene and Jackson, Upper Eocene, age were found in this well.
The suggested the possibilities that the outcrop had not been sufficiently searched for faunas of Paleocene and Jackson age, or that the history of the Eocene of Maryland in the subsurface was very different from that of the Eocene of the outcrop in Maryland and Virginia. If the latter proved to be the case, the questions would remain whether facies changes were responsible for the different faunas of the outcrop and the subsurface, or whether facies changes were responsible for the different faunas of the outcrop and the subsurface, or whether deposition occurred in different areas in the course of Eocene times.
A systematic study of the Foraminifera of the Lower Eocene, Aquia formation, from the outcrop in Maryland and Virginia and from water well samples in Maryland was made to interpret the history of the Lower Eocene in Maryland. The foraminiferal fauna of the Aquia formation is described, and the extent and position of the Aquia beds in the subsurface in southern Maryland are determined.
Another aspect of the investigation involved a distinctive foraminiferal fauna found in the Buchheister water well at Upper Marlboro, Prince George’s County, Maryland, determined by Cushman as Paleocene in age. This raised the questions whether this fauna underlies the typical Aquia Eocene fauna, or whether it is a facies fauna of the Aquia and the beds containing it a time equivalent of the Aquia. The Buchheister well Paleocene fauna proves to be an older fauna than the Aquia fauna.
