Devil’s Postpile National Monument lies within the Ansel Adams Wilderness, near the Mammoth Recreation area south of Yosemite and north of the John Muir Wilderness area. A seasonal, mandatory shuttle brings visitors into the area of the monument, keeping traffic to a minimum and protecting this fragile area. There are countless hiking trails to explore in summer. We chose to walk from the last stop to Rainbow Falls and Lower Falls, where part of the San Joaquin River tumble over basalt cliffs. The granite below is softer, creating a kind of cut-out underneath the falls. There really was a rainbow at Rainbow Falls, while Lower Falls was a quiet, perfect spot for a dip and a snack.
Continuing the walk along the river, through the woods, we arrived at the impressive Devil’s Postpile, a formation of columnar basalt, created when basalt lava from a volcano cooled, contracted and cracked. Since it cooled very slowly, and was very uniform in composition, long, mostly hexagonal columns were formed. Much later, a glacier flowed down part of the San Joaquin River and over that lava, exposing a wall of these columns. Hiking to the top of the post-pile reveals what looks like tiled flooring, with polishing done by the glacier. It’s truly amazing to learn that this was created in nature (and not just here, as similar formations are found throughout the world where similar conditions have occurred). An informational sign at the top explains that the hexagon is nature’s perfect space saver, and besides in basalt columns can be seen in the honeycomb in beehives, on turtle shells and some organic compounds).
More photos from the day