[7][8] The Southwest Mountains are underlain by a belt of Catoctin greenstone, which forms the eastern edge of the Blue Ridge anticlinorium.

In contrast to Oak/Heath Forests, these communities are relatively species-rich, with patchy but diverse herb layers and very few heath shrubs.

"[12] They went on: Characterized by undulating pastures, winding roadways, forested hills, and small hamlets, the district contains a broad range of 18th-, 19th- and early 20th-century rural architecture, reflecting the evolving cultural patterns of more than 250 years of settlement.The estates of Thomas Jefferson, James Madison and James Monroe are all located within the Southwest Mountains, as are many non-presidential estates, including Castle Hill.

Virginia Governor James Barbour, who lived in Orange County, wrote in 1835:[13] Let us, the inhabitants of the South-West Mountains, rejoice and be grateful that our benefits greatly preponderate over our ills.

Mineral resources of soapstone and vermiculite continue to be mined at the southern end of the range.