Before The Collapse
Posted by: 
Volcanoguy
N 42° 56.751 W 122° 10.118
10T E 567823 N 4755136
Quick Description: Geologic history sign at Wizard Island Overlook on West Rim Drive.
Location: Oregon, United States
Date Posted: 11/6/2009 3:09:25 PM
Waymark Code: WM7KWP
Views: 8
Long Description:Marker Name: Before The Collapse
Marker Text: When Mt. Mazama collapsed about 6,800 years ago, it left behind evidences of its former self. Like X-ray photos, the steep caldera walls reveal the interior of Mt. Mazama before its fall. From this point several pre-collapse volcanic features can be identified.
The massive gray monolith on the rim ahead is Llao Rock. It formed when a large outpouring of lava filled an explosion crater on the north slope of Mt. Mazama. When Mt. Mazama collapsed, part of the hardened lava flow broke off and fell into the caldera, leaving the downslope portion perched on the rim.
The jagged, colorful spires of Hillman Peak in the forground are the remains of a secondary volcano which erupted on the side of Mt. Mazama. This satellite cone attained a height of 1,000 feet (300 m). Erosion here has arranged a maze of clogged and solidified lava conduits that fed the Hillman volcano.
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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