Ancient Stone Forest Revealed by Receding Waters
Along the eastern shore of Crowley Lake in Mono County, California, a peculiar geological phenomenon rises from the earth like the remnants of an ancient civilization. Towering up to 20 feet tall and clustered in dense formations, these stone columns first caught the attention of hikers and anglers in the mid-20th century.
At first glance, they appear man-made—chiseled pillars arranged in rows, arches, and vaults. But every one of the roughly 5,000 columns was formed entirely by natural processes over hundreds of thousands of years. Their origin remained a mystery until researchers began to study them closely in the 2000s.
Born from a Supervolcano
Roughly 760,000 years ago, the Long Valley Caldera in eastern California erupted in one of the largest volcanic events in North America. The eruption ejected over 150 cubic miles of volcanic ash and pumice, which blanketed the surrounding landscape.
The ash eventually cooled and solidified into rhyolitic tuff—porous volcanic rock rich in silica. The columns at Crowley Lake began to form soon after, not by cooling cracks like those at Devil’s Postpile, but by hot water and steam moving through the still-warm tuff.
Steam, Minerals, and Time
As snowmelt and groundwater seeped into the hot ash deposits, hydrothermal convection cells formed—systems where water heated by the rock rose as steam and then cooled again in a continuous cycle. These vertical pathways caused minerals like silica and zeolites to precipitate along their walls, slowly cementing the surrounding ash.
Over tens of thousands of years, these cemented tubes became harder than the surrounding rock. As erosion from water and wind wore away the softer material, the vertical columns emerged—some bent, some straight, many seemingly sculpted.
A Hidden Lab in Plain Sight
In recent years, a team led by geologist Noah Randolph-Flagg at UC Berkeley analyzed the columns using microscopy and X-ray imaging. They confirmed the columns formed by mineralization around hydrothermal convection cells, not by cooling fractures.
The findings provided rare surface evidence of deep post-eruption hydrothermal activity. The Crowley Lake Columns now serve as a valuable natural case study for scientists researching volcanic environments. Still publicly accessible by hike or four-wheel drive, the site is monitored by researchers and local authorities to prevent damage to the fragile formations. Their discovery continues to inform studies of similar volcanic terrains around the world.
Along the eastern shore of Crowley Lake in California, strange stone columns rise like ruins.
They seem carved by humans but were shaped by nature.
Their mystery puzzled people for decades—until scientists discovered how steam and minerals formed them after a massive… pic.twitter.com/PQiFC17HBz
— Fascinating True Stories (@FascinatingTrue) August 8, 2025