Deschutes & Ochoco National Forests
Crooked River National Grassland

Oregon Volcanoes

Forked Butte Flows

SUMMARY

Type: cinder cones and flows
Activity: extinct?
Last Eruption: less than 7,700 years ago
Rock Type: basaltic andesite
Eruptive Volume: ? cu km
Latitude: 44.61 N
Longitude: 121.78 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

GEOLOGIC BACKGROUND:

Forked Butte is a large post-Mazama cinder cone on the upland between the glaciated canyons of Jefferson Creek and Cabot Creek. A large flow from south flank of cone spilled southward into the canyon of Cabot Creek. Smaller flows went north into the Jefferson Creek canyon. A second breached cinder cone of similar age on the floor of the canyon of Jefferson Creek was the source of the large flow down Jefferson Creek.

Based on sedimentation rates in nearby lakes an estimated age of 7,400 years has been assigned to this eruption.

HISTORIC ACTIVITY:

• None

DATA SOURCE:

• Date from Scott, 1977.

ADDITIONAL INFORMATION