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Earth of fire

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

Publié le par Bernard Duyck
Publié dans : #Excursions et voyages
Red Mountain - a cinder cone dug by an amphitheater - a click to enlarge - photo Americansouthwest

Red Mountain - a cinder cone dug by an amphitheater - a click to enlarge - photo Americansouthwest

After the Chiricahua hoodoos, another special structure of Arizona with Red Mountain.

As its name suggests, this cinder cone is characterized by a red color, but also by its amphitheater iron horse shape.

Located in the Cococino National Forest about thirty kilometers from Flagstaff, this cinder cone was formed 740,000 years ago in the volcanic field of San Francisco, active for 6 million years.

 

Red Mountain - the amphitheater - a click to enlarge - photo Americansouthwest

Red Mountain - the amphitheater - a click to enlarge - photo Americansouthwest

Digital model of Red Mountain, with details of the various structures - Doc.USGS

Digital model of Red Mountain, with details of the various structures - Doc.USGS

During the eruption, the Red Mountain grew up on a practically flat surface covered by a lava flow extruded at the base of the cone during the waning phase of the eruption.
This lava flow has rafted the ash of the western part of the cone.

The perfect cone has disappeared, and a large natural amphitheater widened in its northeast flank, presumably blown by one or more steam explosions shortly after the end of the eruption : the recently ejected ashes have cooled, but are remained for some time at about 300 ° C, the temperature above the boiling point of water. Rainwater seeped and circulated through hot ashes by creating a mineral cement which bound the ashes together, and formed a  "lid pressure cooker" . The overpressure of trapped waters resulted in steam explosions. Then the erosion of rains and winds expanded over the time this opening, as is suggested by the hoodoos wearing harder sombreros
, and the walls sculpted by the elements.

Red Mountain - ash compacted inside the amphitheater - photo Americansouthwest

Red Mountain - ash compacted inside the amphitheater - photo Americansouthwest

Red Mountain  - Weathered formation of fused cinders, mostly covered by lichen - amerSW

Red Mountain - Weathered formation of fused cinders, mostly covered by lichen - amerSW

Red Mountain - views of the amphitheater and the pinnacles and boulders along the western walls - pictures Americansouthwest
Red Mountain - views of the amphitheater and the pinnacles and boulders along the western walls - pictures Americansouthwest

Red Mountain - views of the amphitheater and the pinnacles and boulders along the western walls - pictures Americansouthwest

Red Mountain  - The boulder sombrero, capping each pinnacle, protects the underlying cinders from erosion. - photo USGS

Red Mountain - The boulder sombrero, capping each pinnacle, protects the underlying cinders from erosion. - photo USGS

Sources :

- USGS - Red Mountain Volcano—A Spectacular and Unusual Cinder Cone in Northern Arizona – link 1link 2

- Hiking Red Mountain Near Flagstaff, Arizona – link

- Summitpost – Red Mountain – link

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