Deschutes & Ochoco National Forests
Crooked River National Grassland

Oregon Volcanoes

Table Rock Volcano

SUMMARY

Type: maar volcano complex
Activity: extinct
Last Eruption: 50,000 to 100,000 years ago
Rock Type: basalt
Eruptive Volume: ? cu km
Latitude: 43.17 N
Longitude: 120.88 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

Table Rock Photo Menu

GEOLOGIC BACKGROUND:

The Table Rock volcano is a large maar volcano complex with tuff ring deposits, a tuff cone, summit lava lake, and feeding dikes. The complex forms an elongate, NNW-trending oval 5.6 by 8.8 km. The highest point is about 395 m above the basin floor.

Table Rock is an erosional remnant of a tuff cone, which at present is a symmetrical cone about 1530 m in diameter at the base, tapering to a diameter of about 360 m at a height of 360 m above the surrounding plain. The cone is capped with flat-lying basalt which once filled the crater, but erosion has modified the original cone, exposing the once-ponded basalt lava lake. Dikes extend north and south of the crater lava lake. On the lower flanks of the cone, the rocks are mostly palagonite lapilli-tuff. Near the summit, the uppermost palagonites are overlain by massive cinders and bombs from fire-fountaining that preceded the filling of the crater with lava.

HISTORIC ACTIVITY:

• None

DATA SOURCE:

• Heiken and others, 1981.

ADDITIONAL INFORMATION