Artist's Drive rises up to the top of an alluvial fan fed by
a deep canyon cut into the Black Mountains. the rock unit provides
evidence for one of the Death Valley area's most violently explosive
volcanic periods. The Miocene-aged (23-5 million years ago) formation is
made up of cemented gravel, playa deposits, and much volcanic debris,
perhaps 5,000 feet (1500 m) thick.

from: Wikipedia