The Basin and Range province has had a complicated geological history and in the last 20 million years features extensional tectonics (tectonic processes involving a dilatation of the crust) represented by normal faults (faults where the downmoving blocks move in a way consistent with gravity). The crust is relatively thin, , and underpinned by an unusually hot mantle which underneath Lunar Crater volcanic field has a slow seismic velocity. Crustal heat flow is low.