BackgroundThree Fingered Jack is a distinctive deeply eroded basaltic andesite shield volcano that forms the highest peak between Mt. Jefferson and the Three Sisters. A pyroclastic cone buttressed by radial dikes forms its sharp-ridged summit. Other Pleistocene shield volcanoes and cinder cones are found to the NW and SW, and Hogg Rock Butte near Santiam Pass is a tuya formed during subglacial eruptions. The Maxwell Butte shield volcano SW of Three Fingered Jack is less eroded, and erupted between about 80,000 and 40,000 years before present.
Source: Smithsonian / GVP volcano information
See also: Sentinel hub | Landsat 8