After California’s Crowley Lake reservoir was completed in 1941, strange column-like formations were spotted on the eastern shore. They had been buried and hidden for eons until the reservoir’s pounding waves began carving out the softer material at the base of cliffs of pumice and ash. The rising gray and stony cylinders have cracks ringing around them at intervals of about 1 foot and have inspired comparisons to Moorish temples. Many are gray, straight as telephone poles and encircled with horizontal cracks about 12 inches apart. Some are reddish-orange in color. Some are bent, or all tilting at the same angle. Still others are half-buried and resemble the fossilized backbones of dinosaurs.
To investigate their origin, geologists at UC Berkeley used a slew of different methods and equipment, including X-ray analysis and electron microscopes. The researchers hypothesize that the columns were created by cold water percolating down into — and steam rising up out of — hot volcanic ash spewed by a cataclysmic explosion 760,000 years ago. The blast, 2,000 times larger than the 1980 eruption of Mt. St. Helens, created the Long Valley Caldera, a massive 10-by-2-mile sink that includes the Mammoth Lakes area. It also covered much of the eastern Sierra Nevada range with a coarse volcanic tuff, or ash fall. The columns began forming as snowmelt seeped into the still-hot tuff. The water boiled, creating evenly spaced convection cells similar to heat pipes. Tiny spaces in these convection pipes were cemented into place by erosion-resistant minerals. [LA Times article]
The columns are usually submerged during the summer, when the water level in the reservoir is high. Good directions for how to find them are here.
updated 10/02/2024
