Deschutes & Ochoco National Forests
Crooked River National Grassland

Oregon Volcanoes

Belknap Volcanic Field

SUMMARY

Type: Holocene shield volcano and associated cinder cones
Activity: extinct
Last Eruption: about 1300 yrs ago
Rock Type: basalt to basaltic andesite
Eruptive Volume: ?
Latitude: 43.19 N to 44.41 N
Longitude: 121.77 W to 121.85 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

Belknap Volcanic Field Photo Menu

GEOLOGIC BACKGROUND:

Belknap volcano is an great Holocene example of the process which built the High Cascade Platform during the Pleistocene. Small shield volcanoes with a capping cinder cone.

A number of other eruptions also occurred in the general area during roughly the same time period. About 1,300 calendar yrs ago (1,330 C14 yrs B.P.) a series of small spatter cones formed between Belknap and Blue Lake. North of these, a phreatic explosion blasted out the crater which is today occupied by Blue Lake. To the south there are a number of cinder cones and associated lava flows, including Collier, Four-in-One, and Yapoah Cones. Four-in-One Cone has been date at about 1,900 calendar yrs old (1,980 C14 yrs B.P.) while Collier is dated at about 1,500 calendar yrs old (1,600 C14 yrs B.P.)

The following are included within this volcanic field:

• Blue Lake
• Spatter Cone Chain
• Belknap Crater
• Little Belknap
• South Belknap Cone
• Yapoah Cone
• Four-in-One Cone
• Collier Cone
  

HISTORIC ACTIVITY:

• None

DATA SOURCE:

• USGS
• Taylor, 1965
• Information on ages from David Sherrod of U.S.G.S. (1996).
  

ADDITIONAL INFORMATION

• Link to U.S.G.S. - CVO's Belknap Shield Volcano Info
• Link to U.S.G.S. Visit a Volcano Info for Belknap Shield Volcano
• Link to VolcanoWorld's Belknap Info