In California, near Crowley Lake bordering the Long Valley caldera, strange, spiral-shaped, 6-meter-high columns joined by high arches were buried and hidden for a long time. The wave erosion of the Los Angeles Department of Water and Power Reservoir dug the softer material at the base of the pumice and ash cliffs.
About 5,000 columns, of various sizes and shapes, are distributed east of the lake on an area of 2 to 8 km².
What is the origin of these strange structures?
Studies from the University of Berkeley reveal its volcanic origin: the columns were created by the penetration of snowmelt into burning volcanic ash from the cataclysmic eruptions of GlassMountain, 760,000 years ago, which destroyed the responsible volcanoes to give the "Bishop tuff". The emptying of the magma chamber caused its collapse and the formation of the Long Valley caldera, 17 km by 32 km.
The water began to boil, meeting the still very hot volcanic materials and generating equidistant convection cells.
The Long Valley Caldera with the Resurgent Dome in the center; in the background, left Glass Mountain, and right, White Mountains - Bratntley / USGS photo
Simplified geological map of the Long Valley area and the distribution of Bishop Tuff. - CVO / USGS map
Analyzes will allow in the future to understand the speed of formation of the columns, their solidification, the chemistry and the temperatures responsible for their spacing, their width and height and their composition.