I traveled today through a venue of volcanic residue. All landscapes had a volcanic origin, but ultimately that's the case of all rock, since sedimentary rock (except, perhaps, for limestone) is made up of eroded igneous rock, and metamorphic rock is re-heated igneous and sedimentary rock. However, this volcanic rock is more immediate and unchanged from when it appeared from the magma below the surface. Most of what can be seen came into being in the last 20 million years--much of it in the last two million years--too little time for erosion to result in compressed sediments that are then uplifted by plates crashing together.
The major feature on today's drive was Crater Lake, a national park since 1902. It was formed with the 10,000-foot Mount Mazama exploded 500,000 years ago. The explosion, from multiple vents, emptied the magma pool under the mountain, and the top of it collapsed, forming a cauldron (not a crater) six miles across. The cauldron, empty of magma, cooled and gradually filled with water. The resulting lake is an average 1,148 feet deep and has a maximum depth of 1,943 feet. Apparently its current level is an equilibrium between accretion and evaporation and seepage because the lake level varies no more than three feet from year to year and season to season, and it has no drainage outlet. The lake never freezes over and its temperature near the surface stays at about 38 degrees Fahrenheit. Scientists have found hot spots 1400 feet below the surface that are at 66 degrees Fahrenheit. It is also deemed the purest lake in the world, with clarity down to 142 feet below the surface.
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Crater Lake with Top of
Wizard Island in Foreground |
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| Banks of Cauldron Around Crater Lake |
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| Wizard Island in Crater Lake |
Wizard Island is a cinder cone that formed in the cauldron of Mount Mazama after Crater Lake had come into existence. There is a boat tour that stops off at Wizard Island, and hikers can climb to its summit, which is 767 feet above the lake's surface.
On the north side of the Crater Lake cauldron is an area called Pumice Desert, which consists of rhyolite ash that was emitted from Mount Mazama. Because pumice is highly porous, the area does not retain water and very few plants have been able to grow on it. Hence, the desert-like appearance at an elevation above 5000 feet.
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View to North from Crater Lake
Showing Pumice Desert |
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| Pumice Desert |
Mileage: 203. Cumulative mileage: 1,920.
