“Neither had iron tools and instead used such hard stones as flint, jade, dolerite, basalt, and serpentine to make axes, knives, and chisels.”

“Dark dolerite mountains of the Warren Range had a light snow cover that accentuated the flow banding in the rock.”

“A tholeiitic suite of dolerite dykes in the southwestern Borrowdale Volcanic Group is a separate, later magmatic event.”