Publication restrictions have been removed. This report is one of a series issued in cooperation with the Army Air Forces and the Bureau of Aeronautics under the supervision of the Aeronautical Board.
Publication restrictions have been removed. This report is one of a series issued in cooperation with the Army Air Forces and the Bureau of Aeronautics under the supervision of the Aeronautical Board.
During Pliocene time a cluster of basaltic and basaltic andesite shield volcanoes was built in the
Three Sisters region. Included in this cluster are the North Sister, Little Brother, Husband, Wife,
Sphinx and Broken Top, the radial dikes and conduit fillings of which have been laid bare by
glacial erosion....