| This map presents the stratigraphic and structural setting of volcanic and sedimentary strata deposited during the past 35 million years across 4,430 square kilometers in central Oregon. Snowfall in the Cascade Range (west part of map area) recharges important aquifers in the Deschutes basin (central part of map). The area includes the majestic peaks of the Three Sisters volcanoes, where continued eruptions of basalt and rhyolite in the past 3,000 years indicate an ongoing volcanic hazard. The Sisters fault zone, with several potentially active faults, traverses the map from southeast to northwest. -- Sherrod et.al., 2004 |
