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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #Eruptions historiques

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?

Crowley Lake and its mysterious columns - photo Feel the planet

Crowley Lake and its mysterious columns - photo Feel the planet

The Crowley Lake Columns - California through my lens photo

The Crowley Lake Columns - California through my lens photo

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

The Long Valley Caldera with the Resurgent Dome in the center; in the background, left Glass Mountain, and right, White Mountains - Bratntley / USGS photo

The Long Valley Caldera, its various apparent structures, and Crowley Lake - Doc. USGS

The Long Valley Caldera, its various apparent structures, and Crowley Lake - Doc. USGS

Simplified geological map of the Long Valley area and the distribution of Bishop Tuff. -  CVO / USGS map

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.

Sources:

- Geologyin - Crowley Lake Columns Solved Mystery - link
- California Volcano Observatory / USGS - Geological history of the Long Valley, Mono Basin region - link

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