ZZYZX, CALIFORNIA–We’ve visited this roadside outcrop on California Highway 178 in the Resting Spring Range on each of our field trips to the Mojave Desert. Meagen Pollock may explain more about this fascinating outcrop later in the blog, but for now I can report that it is a “devitrified pumice tuff, welded tuff, and vesicular vitrophyre” dated by K-Ar methods at 9.5 million years old (Hillhouse, 1987). It is an excellent place for students to put their developing petrologic, stratigraphic and structural skills to the test.
Sarah Appleton on the tuff at Resting Spring Pass showing the zones of sintering.
