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 weather out to yield abundant hollows and caves, giving a "Swiss cheese" appearance to cliffs and slopes. The overall effect is otherworldly but attractive. It's possible these caves may have given the area its name, but if that were the case it should have been "holes" in the wall.

Banshee Canyon, named because of the howling it makes in the desert wind, is a picturesque slot canyon running east-west, a larger fissure in the tuff that has been widened by erosion. It exits out the cliff that bounds the tuff on the west. The striking appearance of the entrance to Banshee Canyon where it breaks the cliff is a more likely source of the name "hole in the wall."

A trail running through Banshee Canyon gives a close-up view of the tuff and its features. Unusually, iron rings suspended from bolts embedded in the rock have been installed at two places where the watercourse, and thus the trail, is nearly vertical. Such direct aid installations are unusual on public trails in natural areas in the US, and are unique in this vicinity.