Sunday, December 6, 2015
I've Been Under, Over, and On a Volcano. Now Let's Go Into a Volcano
Being on a volcano isn't too bad,at least if it isn't erupting. In Hawaii, I've even enjoyed being on an erupting volcano. "On" isn't too hard as a rule. You just drive or walk on it. Being over a volcano takes a little aerial technology, but flying to Seattle on a clear day does the trick. I've occasionally posted aerial shots of the Cascades volcanoes.
just a little bit about these places...
We took our last official field trip of the semester a few weeks back, and our destination was Pinnacles, being our nation's national park, and one of the most scenic and geologically interesting parts of the Coast Ranges (although there are many things that are geologically interesting about the Coast Ranges). Of course, as is my wont, I lectured and talked about the geology, but no lecture can ever compete with field experience. I sent the students up the trails to see the geology up close.
I headed up the Condor Gulch Trail. It connects after 1.7 miles with the High Peaks Trail, which is one of the finest short hikes in North America. My heart was there, but not the time. I made for the Condor Gulch Overlook, and continued another half mile to gain some wonderful views of the surrounding territory.
The Pinnacles volcano erupted near the newly forming San Andreas fault system, and the volcano was actually split in half by the fault motions. One part of it remained in southern California where the exposures are called the Neenach Volcanics. They can be seen in the Lancaster area quite close to the Antelope Valley Poppy Preserve. The rocks on the other side of the fault were carried north some 195 miles (314 kilometers) over 23 million years. It wasn't wasn't fast...maybe 2 inches per year, but the manner in which it happened was pretty violent. Every century or so there would be an earthquake in the range of magnitude 7.5-8.0 that moved the fault 10-20 feet all at once. The process continues today, with the San Francisco earthquake of 1906, the Fort Tejon earthquake of 1857, and the Loma Prieta earthquake of 1989. Enough stress is built up on various segments of the faults to produce large and damaging earthquakes, events that California needs to be prepared for.
From the ridgetop, the landscape appears gentle and serene. The thick brush and Gray Pines hide evidence of a violent past: volcanic eruptions, earthquakes, mudflows, and landslides. Today, the park is a delightful place to explore, with 30 miles of trails. I certainly enjoyed the three miles I traveled the other day.