On a visit to Mammoth Lakes mountain in California’s Eastern Sierras recently, one of my activities was a daylong trip led by Dr. David P. Hill of the US National Geological Survey to view the Long Valley Caldera that was created by a volcanic eruption over 760,000 years ago.

The caldera is over 60 miles long and encompasses Mono Lake and Mammoth Mountain, which was created by a volcanic eruption between 220,00 and 50,000 years ago. Dr. Hill is a leading authority on volcanoes around the world. I’m sure today he is deeply involved and watching with anticipation the volcanic action on Mt. St. Helens, just a few miles north of my home here in Washington State.

When Mt. St. Helens erupted in May of 1980 with earthquakes, huge ash explosions and subsequent lava flow, Mammoth Lakes began to have earthquakes the very next day. These small quakes went on for several years, but as yet there has been nothing like Washington’s explosions. Mono County has had uprisings of roadbeds, high concentrations of carbon dioxide killing trees, but only small rumbling earthquakes so light that they are seldom felt by man.

Part of our trip took us to Lookout Mountain where we could see all of the caldera and the valley it created. The second half of our time was spent at Horseshoe Lake on the backside of Mammoth Mountain. In 1994, following a series of small earthquakes beneath the mountain, scientists detected high concentrations of carbon dioxide gas in the soil adjacent to the lake. Today large volumes of this carbon dioxide are seeping out of the ground at close to 300 tons per day, according to the US Geological Survey.

There are dead or dying trees on over 100 acres of land because the high carbon dioxide concentrations do not permit photosynthesis through absorption of oxygen. In areas of tree kill, carbon dioxide makes up about 20% to 95% of the gas content of the soil; soil gas normally contains 1% or less of CO2, according to the USGS.

I’m still sitting waiting for another explosion here at Mt. St. Helens. She has everyone waiting for more action after the October 1 “burp” of ash. It certainly makes it more interesting to follow today’s news with the basic background of information I garnered while on a visit to Mammoth Mountain.By the way, since Mammoth is so geologically interesting (as well as a world-famous skiing destination, mountain biking, hiking, fishing and exploring region), you might want to visit there soon. Make sure you stop in at the Visitor’s Center and pick up material on the area. Be sure to take the gondola to the top of the mountain where you’ll find a view to end all views.