Geologic units in Falls Church City, Virginia

Sykesville Formation (Cambrian) at surface, covers 72 % of this area: Sykesville Formation - Metasedimentary melange
Lithology: melange
Miocene Sand and Gravel (Tertiary) at surface, covers 6 % of this area: Miocene Sand and Gravel - Sandy gravel, sand, silt, and clay.
Lithology: gravel; sand; silt; clay or mud
Falls Church Intrusive Suite (Cambrian-Ordovician) at surface, covers 22 % of this area: Falls Church Intrusive Suite - Tonalite, granodiorite, monzogranite, and trondhjemite.
Lithology: tonalite; granodiorite; granite; trondhjemite