Shaping the Gorge
Posted by: 
Volcanoguy
N 42° 54.607 W 122° 26.578
10T E 545469 N 4750984
One of three signs at the Rogue River Gorge Viewpoint trailhead interpretive kiosk.
Waymark Code: WM7QNX
Location: Oregon, United States
Date Posted: 11/23/2009
Views: 2
Marker Name: Shaping the Gorge.
Marker Text: The ancient Rogue River once flowed 650 feet below where you are now standing. Then its valley was filled by layer after layer of lava. Geologists call these layers “Intra-canyon basalt flows,” and some theorize that they occurred about 1.25 million years ago. The River had to seek a new way to the sea.
The River begins 27 miles from here, on the slopes of Mt. Mazama. Having cut through the Mazama pumice upstream, it is now carving into the older basalt.
Almost 7,000 years ago, Mt. Mazama (present-day Crater Lake) exploded, sending torrents of whitish pumice and ash down its flanks to the Rogue. The river again sought a new path.
Did the River Carve the Gorge?
The Gorge was likely formed by the collapse of lava tubes and the force of the River as it followed fractures between the layers of lava.
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