Glacial Valleys
Posted by: 
Volcanoguy
N 42° 57.800 W 122° 09.298
10T E 568918 N 4757089
Quick Description: Geologic history sign at Glacial Valleys Viewpoint on West Rim Drive.
Location: Oregon, United States
Date Posted: 11/7/2009 5:25:36 PM
Waymark Code: WM7M4B
Views: 7
Long Description:Marker Name: Glacial Valleys
Marker Text: The collapsed volcano that now holds Crater Lake once stood more than a mile (1.6 km) above the present lake level. Called Mt. Mazama, this massive mountain of overlapping cones was high enough to support a cap of snow all year. During the Ice Age, snow often blanketed the entire mountain - more snow than the summer sun could melt. The accumulated snow compacted to form glaciers, sluggish rivers of ice that carved out broad valleys as they inched down the slopes.
Eventually, the ice in the valleys melted. When the top of Mt. Mazama caved in about 7,700 years ago, the upper portions of the valleys collapsed with it. Today, you can see the remains of two “U”-shaped glacial valleys on the caldera wall across the lake, Kerr Notch (left) and Sun Notch (right).
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