Geology--Conway Robinson State Forest, Gainesville, VA

This diabase (dolerite, volcanic basalt) is on one of the trails at Conway Robinson State Forest In Gainesville VA. pristine. hundreds of millions of years old. awesome.

Conway Robinson State Forest- Diabase

"Almost all of the quarries in Northern Virginia (except the granite quarry near Occoquan) are excavating the diabase and crushing it to the desired sizes, before mixing the rock with cement/sand to form concrete - or with asphalt, for road pavement. The photo shows the diabase quarry located behind Stonewall Jackson HS in Manassas VA."  

Tectonic History of Northern Virginia 

www.virginiaplaces.org/nova/graphics/vulcanmanassas.jpg

geology