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Mineral Resources > Online Spatial Data > Geology > by state > Virginia Geology

Geologic units in Petersburg City, Virginia

Potomac Formation (Cretaceous) at surface, covers 3 % of this area

Potomac Formation - Pebbly, poorly sorted quartzo-feldspathic sand interbedded with sandy clay and silt; minor organic-rich clay and silt

Lithology: sand; clay or mud; silt

Chesapeake Group (Tertiary) at surface, covers 14 % of this area

Chesapeake Group - Fine- to coarse-grained sand, silt, clay; variably shelly and diatomaceous

Lithology: sand; silt; clay or mud

Lower Tertiary Deposits (Tertiary) at surface, covers 2 % of this area

Lower Tertiary Deposits - Glauconitic quartz sand and clay-silt, shelly in part, minor sandy limestone and limey sand; may include the following formations: Brightseat, Aquia, Marlboro, Nanjemay, and Piney Point (Pamunkey Group); and Old Church.

Lithology: sand; silt; limestone

Petersburg Granite (Mississippian) at surface, covers 3 % of this area

Petersburg Granite - Granite

Lithology: granite

Bacons Castle Formation (Tertiary) at surface, covers 68 % of this area

Bacons Castle Formation - Gravel grading upward into sand and sandy clayey silt

Lithology: gravel; sand; silt; clay or mud

Quaternary and Tertiary Deposits (Tertiary-Quaternary) at surface, covers 7 % of this area

Quaternary and Tertiary Deposits - Tabb through Windsor Formations and alluvial/tidal prism deposits.

Lithology: sand; gravel; silt; clay or mud; peat; alluvium

Windsor Formation (Tertiary-Quaternary) at surface, covers 3 % of this area

Windsor Formation - Interbedded gravel, sand, silt, and clay; at altitudes to 85-95 ft. (top of unit).

Lithology: gravel; sand; silt; clay or mud