Geology (and a little History)

Before Mount Mazama completely collapsed, the fiery eruptions bursting from its sides formed many volcanic cones. Mount Scott is the largest of these. (park plaque)

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As Mount Mazama repeatedly erupted for over a half million years, pumice and other lavas welded together at high temperatures. These deposits were then buried and compacted by subsequent lava flows and finally exposed when Mount Mazama completely collapsed. Pumice Castle rock formation is an example. (park plaque)

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Another volcanic cone engulfed in the ever growing Mount Mazama volcano resembles a ghostly ship.

This particular cone was an underground vent that not only contributed to Mazama’s collapse but also contributed to Mazama’s mountain building. It is over 400,000-years-old and the oldest rock in Crater Lake. (park plaque)

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Let’s pause here for a little history…

Discovery Point is so named because on June 12, 1853 John Wesley Hillman and his gold mining expedition reached this very point and discovered an incomprehensible lake that they named, Deep Blue Lake.

 npshistory.com

Two years later William Gladstone Steel visited this area which was still being used by the local native tribes for hunting, gathering, and spiritual purposes.

 historichotels.org

He spent the next 17 years naming Wizard Island, Skell Head, and Llao Rock, campaigning for preserving the lake as a national park, and christening the area with the preferred name Crater Lake. Until then the lake was known as Giiwaas, Blue Lake, Lake Majesty, and Deep Blue Lake. On May 22, 1902, Crater Lake became the 6th National Park. (Oswald, Michael Joseph.  “Crater Lake – Oregon”.  Your Guide to the National Parks.  White Law, WI: Stone Road, 2012.  539.  Print.)

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So….

Mount Mazama grew into a peak of 12,000 feet because of over 400,000 years of repeated volcanic eruptions and the formation and receding of glaciers. It blew some 7,700 years ago during its most violent eruption. It fell as new vents emptied the magma chamber, leaving behind a deep caldera. Centuries of rain and snow filled the basin.  Today, precipitation, evaporation, and seepage create a balance maintaining a constant lake level. Since no streams run into Crater Lake, very little sediment clouds its pristine waters. (park brochure)

But don’t be fooled. Mount Mazama is not an extinct volcano. Wizard Island is a cone that erupted as the lake began to fill.

Will it erupt again?

 park brochure