Description

From Wood and Kienle (1990) ^[1] : "Ingrisarak Mountain is a volcanic vent, composed entirely of red and black basalt scoria. It is 10 x 11 km in size." From Hoare and Condon, 1968 ^[2] : "Basalt (Qb) forms Ingrisarak Mountain, a volcanic vent, and also crops out near the eastern edge of the quadrangle on the flank of a similar vent in the adjoining Marshall quadrangle. Red and black fragments of basalt scoria are widespread in both areas, but no rock was found in place. The fragments have not moved far; they are angular, unweathered, and commonly show ropy flow features. The basalt consists of scattered phenocrysts of pyroxene and olivine in a fine-grained matrix. The basalt is assigned a Quaternary age because it is very fresh appearing and because the volcanic vents, although modified, are still physiographically expressed. Paleomagnetic measurements on oriented specimens from similar volcanic vents in the adjoning Marshall and Kwiguk quadrangles show that the basalt is normally magnetized. The physiographic expression and normal magnetic polarity suggests that the basalt was extruded during the latest (Brunhes) normal polarity epoch ^{[3] [4]} . Recent studies ^{[5] [6]} indicate that the Brunhes epoch began about 0.7 million years ago."