Thursday, December 26, 2013

A Mammoth Mountain Christmas

There aren’t many places in California where one can find snow on Christmas. California Christmases are, for obvious reasons, typically spent trying to avoid bragging to relatives about the weather.

However, there’s one place in California legendary for its snowfall: Mammoth Mountain.

Mammoth is one of the most popular ski areas in the country. People flock to its slopes during the winter; many without pondering the unique geology that creates the snowcapped peak lost in the clouds in this photo.

Mammoth sits in a very unusual place within the Sierra Nevada mountain range. There’s a gaping hole in the middle of the Sierras known as the “Long Valley Caldera”. You can see it reflected in the flatland in the foreground of this image.

The entire flatland in the foreground of this photo is a giant volcano. It erupted over 700,000 years ago, spitting out almost as much lava as the Yellowstone eruptions. When the eruption was finished, the ground collapsed downwards into the now-empty magma chamber, forming the caldera and leaving a giant gaping hole in the center of the mountain range.

The Sierra Nevada range runs parallel to the Pacific Ocean coastline. When moisture from the Pacific tries to enter the continent, it runs into this huge mountain range and typically is dumped as snow. That is, except for one place where moisture is able to penetrate deep into the mountains…because there’s a giant, gaping hole in the center of the range.

Moisture from the Pacific is able to penetrate into the mountains near Long Valley because the highest part of the range at that point was totally blown away. But, there is one mountain sitting in the way, sitting in the path of all that moisture – Mammoth Mountain.

Why is this one mountain sitting in that path, right next to the gaping hole? Well, it’s a volcano too.

Mammoth Mountain is made up of a couple million years worth of lava flows and eruptions, piled on top of one another to build the mountain. It sits just outside of Long Valley caldera, stuck at the perfect place to create massive snowpacks. It exists because of the caldera and it receives its snow because of the caldera.

It’s still active too. In the late 1980’s, there was a series of earthquakes recorded beneath Mammoth due to movement of magma within the crust, and a large number of trees in one area near Mammoth were killed due to venting volcanic gases.

That seems appropriate for a California Christmas. A snowcapped ski course on the slopes of a volcano, sitting along the edge of a giant volcano that blew a massive hole in a mountain range.

Image credit: (Creative Commons license)

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