July 21, 2011

Crater Lake National Park, Oregon

On the way down to Sedona from Washington, I swung by Crater Lake National Park in south central Oregon. In all the times I've driven up and down Oregon over the years, I had never visited Crater Lake. The main reason was because it was usually closed due to the immense snow packs that it gets. When we would go down to California for spring breaks in March and April, it was usually covered with 30-50 feet of snow.

Wizard Island is a cinder cone that rose after the caldera collapsed

In fact, even driving by on July 4th, they had literally just opened the north entrance a few days before and several feet of snow continued to cover the entire park. But, on this spectacular sunny day, the views of the lake and the surrounding Cascade Volcanoes were amazing! Unfortunately there was no hiking available due to the snow cover, so this ended up being a primarily drive through visit. But, perhaps we'll arrange to visit sometime in the late summer and hike up to the summit of Mount Scott (the highest point in the park) for a spectacular 360 degree panorama.

Visible from the slopes of Mount Mazama are Mount Bailey (left), Mount Thielsen (right),
Gaywas Peak (near center), Diamond Peak (distant center), and the Three Sisters (far distance)
 Of course, the story of Crater Lake dates back about 7,600 years to the massive eruption of the 12,000+ foot Mount Mazama. It was the largest volcano in Oregon at the time until a series of eruptions caused an emptying of the magma chamber. One large eruption blasted off the north-face of the volcano in a blast similar to Mount St. Helens. The vast quantity of ash released was some 42 times more powerful than the 1980 Mount St. Helens eruption.

Mount Thielsen is a highly eroded extinct stratovolcano
It rises above the "cinder desert" of Mount Mazama with the Three Sisters visible on left

With the magma chamber emptied, the entire volcano collapsed into the chamber forming this deep caldera that is some 2000 feet deep (it is the deepest lake in the United States). After some later volcanic activity that formed Wizard Island and filled in some of the gaps, rain and snow melt began filling the caldera to form Crater Lake. While there is no obvious outlet for the lake, the lake generally stays at the same level through the years. Hydrologists have identified the oxygen isotopic signature of the lake and determined that none of the springs on the outside of the caldera contain water from the lake (but rather contain just that year's snow melt). So, no one is quite sure where the water goes.

A closeup of 9,500 foot Mount McLaughlin from Crater Lake

This region of Oregon has been particularly volcanically active. There are a number of volcanoes to the north and south of Crater Lake that are visible from the rim. Mount Thielsen and Mount Bailey sit just to the north with Diamond Peak and The Three Sisters visible beyond. To the south you can see Mount McLaughlin and even Mount Shasta in the further distance.

On the southern slopes of Mount Mazama is an interesting canyon area. Here, massive layers of ash and tephra piled up after the pyroclastic flows came down the slopes of the volcano. Still partially molten and hot, steam fumeroles attempted to rise up through the ash layers forming these columns. The higher density of the material made them a bit more resistant to erosion as the stream began cutting into the soft layers.

Crater Lake is definitely a beautiful area and has a fascinating geologic history. We definitely have to get back there in the late summer when the snow melts, so we can do some hiking there!

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