Fort Rock Basin Volcano - John Seach
Oregon, USA

43.30 N, 121.00 W
summit elevation 1716 m
Maar field

The volcano is located in south-central Oregon. It contains almost 40 maars, tuff rings and tuff cones, most which are significantly eroded. The maar volcanoes were produced by the interaction of rising basaltic magma and surface or groundwater.

Volcanic Features of Fort Rock Basin

Fort Rock: This is an isolated tuff ring with spectacular wave-cut cliffs and terraces.
Hole-in-the-ground: This is a nearly circular maar with a diameter of 1.6 km and a depth of 150 m.
Table Rock: This maar complex consists of 2 large tuff rings, 6 smaller tuff rings, and eroded vents. The complex covers an area of 8.8 km x 5.6 km.