After The Collapse
Posted by: 
Volcanoguy
N 42° 56.746 W 122° 10.116
10T E 567825 N 4755127
Quick Description: Geologic history sign at Wizard Island Overlook on West Rim Drive.
Location: Oregon, United States
Date Posted: 11/6/2009 3:21:48 PM
Waymark Code: WM7KWR
Views: 10
Long Description:Marker Name: After The Collapse
Marker Text: About 6,800 years ago, at the climax of a series of dramatic eruptions, the top of Mt. Mazama collapsed. Left behind was the huge crater, or caldera, you see today. But before the caldera filled with water, there were more eruptions.
The most striking evidence of post collapse volcanic activity is Wizard Island, the small volcano in front of you. Its symmetrical cone was formed by a fountain of cinders which erupted from the caldera floor. On the left side of the caldera, a similar cone appeared, but today it lies hidden 496 feet (151 m) below the lake surface.
Geologists believe that lava flows which erupted after the collapse helped to seal the fractured caldera floor, allowing melting snow and rain to accumulate.
NOTE: This sign uses an age of about 6,800 years ago, while most other signs abound the park use about 7,700 years ago. This sign has not been updated to the calibrated age of 7,700 years for the eruption of Mt. Mazama to form Crater Lake.
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