Geologic units in Williamsburg City, Virginia

Windsor Formation (Tertiary-Quaternary) at surface, covers 74 % 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
Moorings Unit of Oaks and Coch (1973) (Tertiary) at surface, covers 15 % 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
Alluvium (Quaternary) at surface, covers 0.2 % of this area: Alluvium - Poorly sorted organic material, clay, sand, and rounded pebbles and cobbles
Lithology: alluvium; clay or mud; sand
Chesapeake Group (Tertiary) at surface, covers 5 % of this area: Chesapeake Group - Fine- to coarse-grained sand, silt, clay; variably shelly and diatomaceous
Lithology: sand; silt; clay or mud
Bacons Castle Formation (Tertiary) at surface, covers 2 % of this area: Bacons Castle Formation - Poorly sorted sand and laminated sand; clay and silt.
Lithology: sand; clay or mud; silt