Rings Loop Trail in Essex, California

The "Hole in the Wall" area, in the middle of the Mojave National Preserve, contains photogenic tuff units, volcanic rocks that were formed, not by a flow of molten lava, but by the settling out of individual particles from a cloud of volcanic ash. If the particles are hot enough to stick together, the result is a "welded" tuff. That's what's happened here. The welding is uneven, so that the less cemented parts weather out more easily. One result is that the tuff weathers into spires and hoodoos and even more convoluted shapes. Another is "cavernous weathering," where the softer areas weath...