Deschutes & Ochoco National Forests
Crooked River National Grassland

Oregon Volcanoes

Hole-in-the-Ground Volcano

SUMMARY

Type: maar
Activity: extinct
Last Eruption: 50,000 to 100,000 years ago
Rock Type: basalt
Eruptive Volume: ?
Latitude: 43.41 N
Longitude: 121.20 W
Location Maps: from TIGER Mapping Service

• State Level - shows state and communities
• County Level - shows county lines, highways, and communities
• Local Level - shows above plus lakes and local roads

Topo Map from TopoZone

Hole-in-the-Ground Photo Menu

GEOLOGIC BACKGROUND:

Hole-in-the-Ground is a volcanic explosion crater or maar located on the west edge of the Fort Rock basin. The floor of the crater is at an elevation of 4340 feet and the surrounding area has an elevation of about 4650 feet. The crater is approximately 1370 m (4500 ft) east-west by 1675 m (5500 ft) north-south. The crater was probably formed in a few days or weeks by a series of explosions due to rising basaltic magma coming into contact with abundant ground water at depth. The magma may have been rising along the fault that is exposed in the crater walls. After the initial explosion, repeated slumping and subsidence along a ring fault led to intermittent closures of the vent, changes is the supply of ground water, and repeated pressure buildup. The layering visible in the rim records the pulsing of the eruption.

HISTORIC ACTIVITY:

• None

DATA SOURCE:

• Jensen, 1995.
  

ADDITIONAL INFORMATION