Granite Dome

Granite domes are domical hills composed of granite with bare rock exposed over most of their surface; such domical features are generally known as bornhardts and can form in any plutonic rock, though they are typically granite or granitic gneiss. As granitic plutons cool kilometers below the surface, minerals crystallize under uniform confining pressure; as erosion brings the rock nearer the surface and the pressure above it decreases, the rock fractures along onion-like exfoliation joints parallel to the land surface, and under the right conditions these sheets of rock peel away to form a dome.