Large boulders of gneiss and schist (high-grade metamorphic rock) cover
alluvial fans along Highway 178 along the western flank of the Black Mountains.
This boulder is a migmatite, a highly deformed metamorphic rock
that has light-colored granitic intrusions (called aplite). Rocks
like these form deep in the Earth's crust. Their exposure in Death Valley
is a testament of the intense tectonic forces shaping the region. |