Saturday, September 29, 2018

The Many Sides of California's Incredible Composite Cone Mt. Shasta

Hotlum Cone and Shastina, the two youngest cones of Shasta are seen here from the north on Highway 97

California has a lot of incredible volcanoes, but looming above them all is Mt. Shasta, the huge composite cone that rises above the mountains of Northern California. At 14,179 feet, it towers over all but a few of the highest peaks of the Sierra Nevada, but none of them are close by. It is more than a mile higher than any other nearby peaks. I and my students have been traveling around it the last two days, and we've seen it from every side.

From the south it was largely hidden by the smoke from the recent wildfires, but we drove up the Everritt Memorial Highway to the 8,000 foot level at Panther Meadows. The barren valley once hosted a ski resort until folks realized the lack of trees in the area was because of the constant avalanches. The ski area was moved, but the road remains, and serves as a high trailhead for summit attempts.
The Sargent's Ridge and Misery Hill cones of Mt. Shasta. These cones are older and more deeply eroded.

A careful study of the ridges and valleys reveals that there have been more than one "Shasta". At least five volcanoes have developed over the Shasta magma chamber, but most of them have been removed by erosion, explosion and avalanche. Only the highest cone, Hotlum, and the satellite summit of Shastina seem untouched by serious erosion. They are both less than 10,000 years old, and Hotlum has continued to erupt at intervals of several hundred years.
From the northeast, Shasta is highly symmetrical. That large snowfields remain in the fall season is evidence of the presence of glaciers. Shasta has at least five of the them, and Whitney Glacier is the longest glacier in all of California, at two miles.

The peak shined bright and clear in the morning light, but by this evening, it was shrouded in clouds and lightning was flashing in the skies above. The mountain, a so-called composite cone is a mountain of many moods.

I'm pretty sure I don't want to see the mountain angry...