The thesis area consists of approximately thirty square miles in the Southern Cascades of Washington near Mount Adams. The oldest exposed rocks are sedimentary volcanic clastics and pyroclastic flows of late-Oligocene age that form a homocline in the northwest corner of the area. A thick pile of younger Tertiary lavas, mudflows, and volcanic clastics unconformably overlie the Oligocene rocks, and contain two hydrothermally altered zones. Andesitic lavas from Mount Adams lap onto older rocks and are of Recent to Pleistocene age. Two glacial till deposits and two airfall pyroclastic layers are present throughout the area. One major fault and two broad folds are present in the area. The geothermal potential is not believed to be great, because genetic relationships indicate the hydrothermal systems that produced the two alteration zones were active only in pre- Pleistocene time. There are no external manifestations of a presently active hydrothermal system with geothermal potential.