Death Valley geology field trip

Badwater

The steep face of the Black Mountains rises from the valley floor. Few visitors realize that these mountains are made up of some of Death Valley's oldest rocks. Photo by Ray Nordeen, NPS.

The oldest rocks - Relics of the Precambrian world in Death Valley The steep face of the Black Mountains is made up of some of the oldest rocks in Death Valley. These 1.7 billion-year-old Precambrian rocks are the remnants of an ancient volcanic mountain belt with flanking deposits of mud and sand. About 1.8-1.7 billion years ago, these volcanic and sedimentary rocks were severely metamorphosed—altered, recrystallized, and partially remelted by the Earth's internal heat and by the load of overlying younger rocks. The original rocks were transformed to contorted gneiss, making their original parentage almost unrecognizable.

1.7 billion-year-old metamorphic rocks. Quartz-feldspar gneiss dominates the mountain face above Badwater. Photo by Marli Miller.

11 million years ago, these venerable rocks were injected with magma that solidified to form the Willow Spring pluton. The diorite to gabbro composition of the Willow Spring pluton blends well with the dark Precambrian gneiss, so you'll have to look carefully to see the contact between the two rock types.