BackgroundThe Saddle Butte volcanic field in SE Oregon consists of a 1100 km2 area of Pleistocene basalts with a superposed 240 km2 area of younger basalts. The younger flows were considered to be of possible Holocene age (Wood and Kienle, 1990), however Sherrod et al. (1989) mapped the volcanic field as Pleistocene, and a K-Ar date of 0.43 +/-0.09 million years was obtained. Oregon state Highway 78 cuts across the western side of the isolated lava field. The volcanic field is separated from the adjacent Jordan Craters field to the east by the Owyhee River and resembles the lava fields of the Snake River Plain in Idaho. Vents on the flanks of the Sheepshead Mountains at the far western end of the lava field produced lava-tube-fed flows across gently sloping terrain to the east. The most recent flow of the Saddle Butte volcanic field is known for its abundant lava tubes, including the so-called 40-Mile Cave, which is actually part of a tube system that is 13.5 km long.
Source: Smithsonian / GVP volcano information
See also: Sentinel hub | Landsat 8