page_title: Rogue River (Oregon)
section_title: High and Western Cascades
hierarchical_section_title: Rogue River (Oregon) / Geology / High and Western Cascades
caption_attribution_description: Crater Lake from above
context_page_description: The Rogue River in southwestern Oregon in the United States flows about 215 miles in a generally westward direction from the Cascade Range to the Pacific Ocean. Known for its salmon runs, whitewater rafting, and rugged scenery, it was one of the original eight rivers named in the Wild and Scenic Rivers Act of 1968. Beginning near Crater Lake, which occupies the caldera left by the explosive volcanic eruption of Mount Mazama, the river flows through the geologically young High Cascades and the older Western Cascades, another volcanic province. Further west, the river passes through multiple exotic terranes of the more ancient Klamath Mountains. In the Kalmiopsis Wilderness section of the Rogue basin are some of the world's best examples of rocks that form the Earth's mantle. Near the mouth of the river, the only dinosaur fragments ever discovered in Oregon were found in the Otter Point Formation, along the coast of Curry County.
  People have lived along the Rogue River and its tributaries for at least 8,500 years. European explorers made first contact with Native Americans toward the end of the 18th century and began beaver trapping and other activities in the region.
context_section_description: Arising near Crater Lake, the Rogue River flows from the geologically young High Cascades through the somewhat older Western Cascades and then through the more ancient Klamath Mountains. The High Cascades are composed of volcanic rock produced at intervals from about 7.6 million years ago through geologically recent events such as the catastrophic eruption of Mount Mazama in about 5700 BCE. The volcano hurled 12 to 15 cubic miles (50 to 63 km³) of ash into the air, covering much of the western U.S. and Canada with airfall deposits. The volcano's subsequent collapse formed the caldera of Crater Lake.
  Older and more deeply eroded, the Western Cascades are a range of volcanoes lying west of and merging with the High Cascades. They consist of partly altered volcanic rock from vents in both volcanic provinces, including varied lavas and ash tuffs ranging in age from 0 to 40 million years. As the Cascades rose, the Rogue maintained its flow to the ocean by down-cutting, which created steep narrow gorges and rapids in many places. Bear Creek, a Rogue tributary that flows south to north, marks the boundary between the Western Cascades to the east and the Klamath Mountains to the west.
caption: Crater Lake, the remains of Mount Mazama
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