After The Collapse
Posted by: Groundspeak Premium Member Volcanoguy
N 42° 56.746 W 122° 10.116
10T E 567825 N 4755127
Geologic history sign at Wizard Island Overlook on West Rim Drive.
Waymark Code: WM7KWR
Location: Oregon, United States
Date Posted: 11/06/2009
Published By:Groundspeak Regular Member silverquill
Views: 10

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.

Historic Topic: Geological

Group Responsible for placement: National Parks Service

Marker Type: Roadside

Region: Willamette Valley

County: Klamath

State of Oregon Historical Marker "Beaver Board": Not listed

Web link to additional information: Not listed

Visit Instructions:

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Recent Visits/Logs:
Date Logged Log User Rating  
OregonTrailRanger visited After The Collapse 11/27/2020 OregonTrailRanger visited it
cd.cuts visited After The Collapse 08/22/2013 cd.cuts visited it
ChapterhouseInc visited After The Collapse 07/13/2013 ChapterhouseInc visited it
bachmann_andreas visited After The Collapse 12/12/2011 bachmann_andreas visited it
Volcanoguy visited After The Collapse 08/25/2009 Volcanoguy visited it

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