Crater Lake National Park
Oct 3, 2010
Mile 4373- 4584
Crater Lake National Park is located in south-central Oregon, along the eastern edge of the Cascades. It is aptly named: a lake in a crater, and it is lovely, though I was probably more impressed by the concept than the beauty.
The crater in question was formed approximately 7,700 years ago, in the climactic eruptions of Mount Mazama. That mountain had been formed over hundreds of thousands of years of regular eruptions, alternately being built up by its own ash and pumice and being eroded by passing glaciers. Over time, the pressure of the magma under the volcano caused additional vents to
develop, and in one final enormous eruption, the magma chamber was virtually emptied, and the weakened cone collapsed into itself, leaving the depression now known as Crater Lake. The NPS brochure explains: “Ash from these eruptions lies scattered over eight states and three Canadian provinces’ some 5,000 square miles were covered with six inches of Mazama’s ash. In the park’s Pumice Desert ash lies 50 feet deep.”
Eventually, additional volcanic eruptions caused the floor of the remaining caldera to be sealed, and rain and snowmelt began to collect in the basin. Further eruptions built up small cones within the crater – one of which is visible
above the water line as Wizard Island. Today, Crater Lake is the deepest lake in the United States, and in the top ten in the world (some sources say 7th, some 9th… ). The great depth is what causes the deep blue color, though the day I was there the light angle was only bringing out a lighter blue, though still very pretty.
The rock formations are Crater Lake were pretty fascinating, and I have no clue what caused most of them. The “pinncales” or “hoo-doos” in these photos, though, I know to have been created by steam vents. As hot underground gasses continued to escape through the molten lava, the resulting rock was flash-hardened into these spires. Eventually, streams (such as the one at the bottom of this valley) eroded away the surrounding rock, and these ultra-hard tubes
remain. Apparently, most are still hollow inside.