Wednesday, August 7, 2013

Fire And Ice

Once Mt. Mazama had collapsed within itself in a terminal cataclysm, the resulting caldera no doubt resembled the visage of hell from “Dante’s Inferno” -- a seething bottom of molten debris, fragments of sharp rock and pools of bubbling mud.

During the growth of Mt. Mazama, episodes of glacier accumulation had alternated with periods of volcanic eruption. Lava flows and showers dissipated the glaciers on the slopes of the caldera, creating torrents of melted water sweeping into the newly formed basin.

So as you might expect, Crater Lake was no overnight sensation. Over the course time, a lake eventually appeared in the caldera: first as series of small pools, then larger pools with connecting channels, and finally as a singular continuous and ever deepening body of water.

“As passing clouds unburdened themselves of their moisture, the level of the lake gradually rose,” wrote Howel Williams in "Crater Lake: The Story of Its Origin." “Four-fifths of the water fell directly into the lake as rain and snow: the remainder was supplied by small torrents cascading into the basin from the encircling cliffs.”

Today, the level lake is fairly constant, aside from minor seasonal fluctuations. Crater Lake has no inlets or outlets. The amount of water added by rain, snow and streams inside the caldera wall keeps pace with that lost by evaporation and percolation through the walls.

As the deepest body of fresh water in the U.S. and seventh deepest in the world, Crater Lake is approximately 1,932 feet deep. Indeed, the lake is so deep that it rarely freezes over, with recorded freezes occurring only in 1924, 1949 and 1983.

The immense depth of Crater Lake acts as a heat reservoir that absorbs and traps sunlight, maintaining the water temperature at an average of 55 degrees Fahrenheit on the surface and 38 degrees at the bottom. The surface temperature fluctuates a bit, but the bottom temperature remains quite constant.

All told, it likely took thousands of years for the caldera to transform from a hellish vision of Dante’s underworld to the heavenly views of the stunningly beautiful blue pool we see today (below, with my Mom posing on one of our trips to Crater Lake).

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