A photo diary on a particularly interesting rock formation in eastern California — a columnar basalt known as Devils Postpile. Photos taken in August, 2013 while I was on a 6-day driving tour of the Sierras.
Devils Postpile National Monument is a 798-acre national monument created in 1911 by President Taft. It is now within the boundaries Ansell Adams Wilderness, and previously to 1905 the area was within the boundaries of Yosemite National Park.
Besides the rock formation there is Rainbow Falls, where the Middle Fork of the San Joaquin River plunges over a 100-foot drop.
Access to the trail head is via a shuttle bus that comes down from the Mammoth Mountain Ski Area. The shuttle can be busy since this is one of the access points for the John Muir and Pacific Crest trails used by backpackers.
A side trail works up the hill and allows you access to the top of the formation.
Part of the haze in these pictures is due to smoke from a large fire currently burning in the central Sierras. Half of the people staying in the hotel in Bishop, CA that I used were firefighters.
Rainbow Falls cuts through an area where magma cooled differently and fractured vertically. The water then undercuts the rock at the top and the falls are slowly moving upstream.
The geology of the Sierra Nevada range is a bit complex. However, most of the features pictured here are less than 100,000 years old and are essentially volcanic in origin (magma, pumice, etc.) that were then modified by glaciation. The granites and gneisses of the range are older. Wikipedia: Geology of the Yosemite Area covers this in more detail. Further north around Mono Lake is an area with much more recent volcanic activity. (Which was visited later the same day — but will be the subject of a different diary.)