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

Geologic units in Richmond county, Virginia

Bacons Castle Formation (Tertiary) at surface, covers 0.9 % of this area

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

Lithology: gravel; sand; silt; clay or mud

Shirley Formation (Quaternary) at surface, covers 5 % of this area

Shirley Formation - Interbedded gravel, sand, silt, clay, and peat; at altitudes to 35-45 ft. (top of unit).

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

Quaternary and Tertiary Deposits (Tertiary-Quaternary) at surface, covers 2 % 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

Moorings Unit of Oaks and Coch (1973) (Tertiary) at surface, covers 16 % of this area

Moorings Unit of Oaks and Coch (1973) - Sand, silt, and clay; at altitudes from 100-130 ft. (top of unit).

Lithology: sand; silt; clay or mud

Windsor Formation (Tertiary-Quaternary) at surface, covers 12 % 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

Chesapeake Group (Tertiary) at surface, covers 26 % of this area

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

Lithology: sand; silt; clay or mud

Alluvium (Quaternary) at surface, covers 1 % of this area

Alluvium - Poorly sorted organic material, clay, sand, and rounded pebbles and cobbles

Lithology: alluvium; clay or mud; sand

Pliocene Sand and Gravel (Tertiary) at surface, covers 2 % of this area

Pliocene Sand and Gravel - Sandy gravel, gravelly sand, poorly to well-sorted sands, and thin- to medium-beds of clay and silt, at altitudes from 170-320 ft. (top of unit).

Lithology: gravel; sand; clay or mud; silt

Tabb Formation: Lynnhaven and Poquoson Members (Quaternary) at surface, covers 8 % of this area

Tabb Formation: Lynnhaven and Poquoson Members - Undifferentiated Qtl, Qts.

Lithology: sand; silt

Tabb Formation; Sedgefield Member (Quaternary) at surface, covers 6 % of this area

Tabb Formation; Sedgefield Member - Pebbly to bouldery, clayey sand and shelly sand, at altitudes to 30 ft. (top of unit).

Lithology: sand

Bacons Castle Formation (Tertiary) at surface, covers 19 % of this area

Bacons Castle Formation - Poorly sorted sand and laminated sand; clay and silt.

Lithology: sand; clay or mud; silt