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Tuff Cone, Oregon

Gallery of Volcano Types

Tuff cones form when a maar acquires a backbone of lava. (more below)
A maar with a lava backbone
Photo (c) 2005 Andrew Alden, licensed to About.com (fair use policy)
The tuff cone of Table Rock, by the shores of the dry Silver Lake in central Oregon, started out as a maar, where magma intruded into water and triggered explosive eruptions. Its cone of tuff rose higher than usual, enough to briefly escape the influence of water, and filled with a lava lake. Erosion took away the sides of the crater, revealing the large basalt dikes in the foreground and elsewhere, and the center of the lava cap remained, turning what was a crater bottom into a mountaintop. Geologists can study this butte and visualize the larger tuff cone that once stood here.

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