- Source: Tomstown Dolomite
The Tomstown Dolomite or Tomstown Formation is a geologic formation in Maryland, Pennsylvania, Virginia and West Virginia. It preserves fossils dating to the Cambrian Period.
In Maryland it is described as "Interbedded light gray to yellowish-gray, thin- to thick-bedded dolomite and limestone; some shale layers; gradational contact with Antietam; thickness 200 to 1,000 feet."
In southern Maryland it is divided into four members:
Dargan Member Interbedded and cyclical dolomite and limestone.
Benevola Member Light gray to white, massive to poorly bedded, highly fractured sugary dolomite.
Fort Duncan Member Medium- to dark-gray, thick bedded, mottled dolomite with white, void-filling sparry dolomite.
Bolivar Heights Member Three lithologies from the basal layer of a tan, vuggy dolomite, to a light gray dolomitic marble called the Keedysville bed, to thin- to medium bedded layers of lime mudstone containing burrows.
See also
List of fossiliferous stratigraphic units in Maryland
List of fossiliferous stratigraphic units in Pennsylvania
List of fossiliferous stratigraphic units in Virginia
List of fossiliferous stratigraphic units in West Virginia
References
Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.