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

Geologic units in Stafford county, Virginia

Garrisonville Mafic Complex (Proterozoic Z-Cambrian) at surface, covers 7 % of this area

Garrisonville Mafic Complex - Metamorphosed mafic and ultramafic rocks

Lithology: amphibolite; hornblendite; greenstone

Plagiogranite Tonalite (Cambrian-Ordovician) at surface, covers 8 % of this area

Plagiogranite tonalite

Lithology: tonalite

Quantico Formation - Slate and porphyroblastic schist (Ordovician) at surface, covers 2 % of this area

Quantico Formation - Slate and porphyroblastic schist

Lithology: slate; schist

Lower Tertiary Deposits (Tertiary) at surface, covers 16 % 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

Charles City Formation (Quaternary) at surface, covers 1 % of this area

Charles City Formation - Interbedded sand, silt, clay and minor gravel; at altitudes to 70-80 ft. (top of unit).

Lithology: sand; silt; clay or mud; gravel

Mylonite, Mylonite Gneiss, and Cataclastic Rocks (Proterozoic - Paleozoic ?) at surface, covers < 0.1 % of this area

Mylonite, mylonite gneiss, and cataclastic rocks.

Lithology: mylonite; gneiss; cataclastite

Potomac Formation (Cretaceous) at surface, covers 12 % 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

Amphibole Metagabbro (Cambrian) at surface, covers < 0.1 % of this area

Amphibole Metagabbro

Lithology: amphibolite; gabbro

Alluvium (Quaternary) at surface, covers 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 6 % of this area

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

Lithology: sand; silt; clay or mud

Quantico Formation - Micaceous quartzite (Ordovician) at surface, covers 0.1 % of this area

Quantico Formation - Micaceous quartzite

Lithology: quartzite; schist

Chopawamsic Formation - Interlayered felsic and mafic metavolcanic rocks (Cambrian) at surface, covers 6 % of this area

Chopawamsic Formation- Interlayered felsic and mafic metavolcanic rocks

Lithology: metavolcanic rock

Pliocene Sand and Gravel (Tertiary) at surface, covers 4 % 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

Goldvein Pluton (Cambrian-Ordovician) at surface, covers 0.9 % of this area

Goldvein Pluton - Metamonzogranite.

Lithology: granitic gneiss

Holly Corner Gneiss (Proterozoic Z-Cambrian) at surface, covers 1.0 % of this area

Holly Corner Gneiss - Hornblende-biotite gneiss

Lithology: mafic gneiss

Windsor Formation (Tertiary-Quaternary) at surface, covers 1 % 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

Falmouth Intrusive Suite (Mississippian - Pennsylvanian) at surface, covers 0.3 % of this area

Falmouth Intrusive Suite - Granite, quartz monzonite, granodiorite, and tonalite

Lithology: granite; quartz monzonite; granodiorite; tonalite

Lunga Reservoir Formation (Cambrian) at surface, covers 12 % of this area

Lunga Reservoir Formation - Metadiamictite.

Lithology: metasedimentary rock; meta-conglomerate

Ta River Metamorphic Suite (Cambrian) at surface, covers 0.1 % of this area

Ta River Metamorphic Suite - Amphibolite gneiss

Lithology: amphibolite; gneiss; schist; quartzite; biotite gneiss; felsic volcanic rock; gabbro; granite

Tabb Formation (Quaternary) at surface, covers 2 % of this area

Tabb Formation - Undifferentiated. Includes the Poquoson Member (Qtp), Lynnhaven Member ( Qtl) and Sedgefield Member (Qts).

Lithology: sand; silt; peat

Phyllite (Cambrian-Ordovician) at surface, covers 4 % of this area

Phyllite.

Lithology: phyllite

Porphyroblastic Garnet-Biotite Gneiss (Proterozoic Y) at surface, covers 0.5 % of this area

Porphyroblastic garnet-biotite gneiss.

Lithology: biotite gneiss

Metasedimentary Rocks Undivided (Cambrian-Ordovician) at surface, covers 2 % of this area

Metasedimentary rocks

Lithology: metasedimentary rock; quartzite; schist; phyllite;

Miocene Sand and Gravel (Tertiary) at surface, covers 5 % of this area

Miocene Sand and Gravel - Sandy gravel, sand, silt, and clay.

Lithology: gravel; sand; silt; clay or mud

Falls Run Granite Gneiss (Silurian) at surface, covers 2 % of this area

Falls Run Granite Gneiss - Granite

Lithology: granite

Bacons Castle Formation (Tertiary) at surface, covers 0.5 % 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 1 % 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

Diorite Gneiss (Proterozoic) at surface, covers 0.6 % of this area

Diorite gneiss

Lithology: gneiss

Trondhjemite (Cambrian-Ordovician) at surface, covers 0.7 % of this area

Trondhjemite

Lithology: trondhjemite