Today we took a full day break from the classroom at the Deer Creek Center in order to visit Crater Lake which is about 2.5 hours away. We woke up to another soggy, cold morning, ate breakfast, packed lunch and then got in the Suburbans.
The drive included our third stop at Dutch Bros. Coffee this trip and an episode of carsickness, but after a few hours we pulled up to the park. At our first stop, Megan gave us an introduction to the geology behind Crater Lake. We learned that in addition to Basin and Range faulting, there is faulting related to the formation of the caldera that is Crater Lake.
In short, Mt. Mazama stood where the lake now resides. After the magma chamber underneath Mt. Mazama was emptied in a climactic eruption event about 6800 years ago, the ground quickly and dramatically subsided resulting in a series of steep normal faults in a ring pattern. This was because there was no longer material underneath Mt. Mazama to support it’s load. This resulted in the caldera that ultimately became Crater Lake. Over time, the caldera widened as a result of erosion and filled with snowmelt to become the 1900 ft deep lake we see today.
When I saw the lake for the first time, my jaw dropped. It is much bigger than anything I imagined and the water is so blue and so still. I’ve never seen anything like it. After lunch at some picnic tables, we drove around the entire rim of the volcano and made several stops while we filled out a worksheet Megan prepared for us. The stops included viewing a rhyodacite outcrop near Cleetwood Point, a welded tuff named Wineglass Tuff, and Phantom Ship, the throat of an andesitic volcano that got plugged, cooled and eroded in the shape of a creepy ship. Today there is andesitic volcanic activity in the center of the caldera (under the water).
After we wrapped up at Crater Lake, we got back in the Suburbans and headed back towards Selma. We stopped at Elmer’s Diner in Grants Pass and I ate my weight in french fries and blackberry cobbler with ice cream on top. Tomorrow is the last full day before we drive back to Stanford!