Vanished Volcano
Posted by: 
Volcanoguy
N 42° 44.035 W 122° 01.034
10T E 580448 N 4731735
Geologic history sign titled Vanished Volcano, about formation of Crater Lake.
Waymark Code: WM7KEF
Location: Oregon, United States
Date Posted: 11/04/2009
Views: 6
Marker Name: Vanished Volcano
Marker Text: For thousands of centuries the landscape in front of you was dominated by a massive and explosive volcano called Mt. Mazama. Like today’s major Cascade stratovolcanoes, it slept for long intervals under a mantle of ice and snow, periodically bursting into activity.
About 7,700 years ago a series of dramatic eruptions shook Mt. Mazama. Rocks and ash exploded into the air and fell hundreds of miles away. Avalanches of glowing-hot rocks poured from the volcano, creating the flat valley you are standing on. Then, the top of Mt. Mazama collapsed, leaving behind a 6-mile wide (10 km) caldera.
Today the base of Mt. Mazama contains the deepest lake in the United States -- Crater Lake. You are now standing at about the same elevation as the lake bottom, more than 1,900 feet (580 m) below the water’s surface.
Just ahead 3 1/2 miles (5.6 km) lies the south entrance to Crater Lake National Park which preserves the magnificent legacy of Mt. Mazama for all to enjoy.
NEW and UPDATED Marker and Text:
From here you can see the truncated peaks of an enormous volcano that stood about 12,000 feet, towering over the landscape. Formed slowly over half a million years, the destruction of Mount Mazama took only days. Its climactic eruption 7,700 years ago began with a blast of rock and ash blown into the stratosphere. New vents encircling the peak brought hot flows of pumice, ash, and gas down its flanks burying the landscape, creating this flat valley. So much of the magma chamber was drained, the volcano had no support. It fell in a massive collapse, creating the basin that would hold Crater Lake. You are standing at about the same elevation as the bottom of Crater Lake.
Visit Instructions:
Include your thoughts and observations pertaining to this location and your visit. Provide any additional history that you are aware of that pertains to this location. If the marker commemorates a historic building tell us what it is used for now or share with us the circumstances of an earlier visit to bring this locations history to life.
Please upload a favorite photograph you took of the waymark. Although visiting this waymark in person is the only thing required of you to receive credit for your visit, taking the time to add this information is greatly appreciated.
Be creative.