A Mammoth Perspective

Long Valley from Mammoth

For the last three days I’ve been skiing at Mammoth Mountain, an 11,059-foot volcano built to its current shape between 110,000 and 57,000 years ago. It is still active. The mountain’s last eruption of rock and lava was about 1200 years ago, essentially in the geologic present. Lethal gasses burp out of fissures, and hot springs push steam through snow. Up to 150 tons of carbon dioxide seep out of the mountain — enough to produce a necklace of “tree kills” around its base. In 2006, three members of the Mammoth Mountain ski patrol were killed by gasses from a volcanic vent.

Mammoth overlooks the Long Valley Caldera on the east side, which is where most of the ski runs are. That’s it in the photo above, which I shot yesterday from the summit. About 760,000 years ago, a short tick before the geologic present, a supervolcano stood where Long Valley is now.Long Valley Caldera It was obliterated in one of the largest explosions in the known history of the Earth. Over 150 cubic miles of material were blown out, so violently and completely that what remained was a wide deep crater. Lava flows spread for dozens of miles, while ash and debris spread from the Pacific to Kansas. The image on the right (via Wikipedia and courtesy of Roy A. Bailey, USGS Volcanologist with the USGS in Menlo Park) is a cross section of the view above.

To put this in perspective, Krakatoa blew 5 cubic miles into the sky. Mount St. Helens blew out less than one cubic mile. Long Valley was a VEI7 event. Only VEI8 events are bigger. Perhaps the biggest risk of a similar event is the Yellowstone caldera, which sits over a hot spot that has already produced four cataclysms exceeding the Long Valley one. Only two other events have been larger than any of those, and the largest was in Colorado. All were VEI8 events. Here’s a list of those, from Wikipedia, in decreasing order of material displaced:

  1. La Garita CalderaColorado, United States—Source of the enormous eruption of the Fish Canyon Tuff ~27.8 million years ago (~5,000 km³) This was in
  2. Lake TobaSumatraIndonesia—~74,000 years ago (~2,800 km³). The Lake Toba eruption plunged the Earth into a volcanic winter, eradicating an estimated 60%[11][12][13][14] of the human population (although humans managed to survive even in the vicinity of the volcano[15]).
  3. Island Park CalderaHuckleberry Ridge TuffIdaho/Wyoming, United States, Yellowstone hotspot—2.1 million years ago (2,500 km³)[8]
  4. Atana Ignimbrite, Pacana Caldera, northern Chile—4 million years ago (2,500 km³)[9]
  5. Whakamaru, Taupo Volcanic Zone, North Island, New Zealand—Whakamaru Ignimbrite/Mount Curl Tephra ~254,000 years ago (1,200–2,000 km³)[7]
  6. Heise volcanic field, Kilgore Tuff, Idaho, United States, Yellowstone hotspot—4.5 million years ago (1,800 km³).[10]
  7. Heise volcanic field, Blacktail Tuff, Idaho, United States, Yellowstone hotspot—6.6 million years ago (1,500 km³).[10]
  8. Lake Taupo, Taupo Volcanic ZoneNorth IslandNew ZealandOruanui eruption ~26,500 years ago (~1,170 km³)
  9. Cerro GalanCatamarca ProvinceArgentina—2.5 million years ago (1,050 km³)
  10. Yellowstone CalderaLava Creek TuffWyomingUnited StatesYellowstone hotspot—640,000 years ago (1,000 km³)[8]

Following that is a list of  VEI7 events, including Long Valley:

Over the last 3/4 million years, the Long Valley Caldera has been decorated by many smaller volcanic eruptions and formations (including Mammoth), as well as by glacial advances and retreats and gradual erosion. The result looks as innocent as any other valley filled with cones and old tuff — though less innocent than Yellowstone, whose charms are mostly those of hot water.

Still, knowing the provenance of Long Valley and Mammoth gives the observer reason to pause and wonder — not only at the hugeness of Earth’s formative events, but of our species’ oblivity to them.

Bonus links:

8 comments

  1. référencement grenoble’s avatar

    it looks like the great moutains we have here. peaceful and beautiful. but we don’t have mammoth, sick..

  2. Robin L’s avatar

    Great photo, interesting place… thanks!

  3. kata mutiara cinta’s avatar

    Nice Picture, it’s very amazing scenery, Great share!

  4. Bali wedding photography’s avatar

    Great photograph, must’ve taken quite an effort to get up where you were!

  5. Daly @ Write a Bio’s avatar

    It’s amazing how many natural wonders we have on this Earth, and it’s even more amazing how we forget about them easily.

  6. Grace Sullivan’s avatar

    Beautiful picture – looks like long, peaceful runs…until you read the history of the mountain! Amazing.

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