Deschutes & Ochoco National Forests
Crooked River National Grassland

Oregon Volcanoes

Four Craters Flows

SUMMARY

Type: lava flow field
Activity: extinct
Last Eruption: less than 50,000 years ago
Rock Type: basalt
Eruptive Volume: ?
Latitude: 43.37 N
Longitude: 120.67 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

Four Craters Photo Menu

GEOLOGIC BACKGROUND:

The Four Craters field covers about 30 square kilometers. Four Pleistocene cinder cones are the source of the flows in the field and are aligned along a fissure trending N 30° W. The cones rise 75 to 120 meters above the flows and the distance beween the northern most and southern most cones is about 3.5 kilometers.

Closely related to the Four Craters lava field is Crack-in-the-Ground located at the southwest corner of the field. The eruptions from the field were accompanied by a slight sinking of the older rock surface. This shallow, graben-like sink is about 3 kilometers wide and extends to the south into an old lake basin. Crack-in-the-Ground marks the western edge of this small, volcano-tectonic depression and is nearly 9 meters deep and over a meter wide. The crack is the result of a tension fracture along a hingeline produced by the drapping of Green Mountain lava flows over the edge of upthrown side of the concealed fault zone.

HISTORIC ACTIVITY:

• None

DATA SOURCE:

• Jensen, 1995.
  

ADDITIONAL INFORMATION