Tomstown Dolomite

Tomstown Dolomite (Stose, 1906). Dolostone, limestone and minor chert. Dolostone (upper member), light- to dark gray, fine- to coarse-grained, medium- to thick-bedded, locally laminated with white chert nodules in uppermost beds; about 600 feet thick. Dolostone (high magnesian member), very-light-gray to yellowish-white, medium- to coarse-grained, very-thick-bedded, locally dark-gray, fine-grained and with white, coarse-grained, lenticular dolostone mottling; about 200 feet thick. Limestone, very-dark-gray, very-fine-grained, thin-bedded, partly dolomitic, with shaly partings; about 325 feet thick. The Tomstown is lithologically similar to, but thinner than the Shady Dolomite of south western Virginia and conformably overlies the Antietam Formation.
State Virginia
Name Tomstown Dolomite
Geologic age Cambrian
Lithologic constituents
Major
Sedimentary > Carbonate > Dolostone
Minor
Sedimentary > Chemical > Chert
Comments Appalachian Plateaus and Valley and Ridge; Blue Ridge Anticlinorium (Northern)
References

Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.

Virginia Division of Mineral Resources, 2003, Digital Representation of the 1993 Geologic Map of Virginia, Publication 174, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, scale 1:500,000.

NGMDB product
Counties Loudoun