page_title: Mount Jefferson (Oregon)
section_title: Physical geography
hierarchical_section_title: Mount Jefferson (Oregon) / Geography / Physical geography
caption_attribution_description: Mt. Jefferson from Russell Lake.
context_page_description: Mount Jefferson is a stratovolcano in the Cascade Volcanic Arc, part of the Cascade Range in the U.S. state of Oregon. The second highest mountain in Oregon, it is situated within Linn County, Jefferson County, and Marion County and forms part of the Mount Jefferson Wilderness. Due to the ruggedness of its surroundings, the mountain is one of the hardest volcanoes to reach in the Cascades. It is also a popular tourist destination despite its remoteness, with recreational activities including hiking, backpacking, mountaineering, and photography. Vegetation at Mount Jefferson is dominated by Douglas fir, silver fir, mountain hemlock, ponderosa pine, lodgepole pine, and several cedar species. Carnivores, insectivores, bats, rodents, deer, birds, and various other species inhabit the area.
  Also known as Seekseekqua by Native American populations, the volcano was named after United States President Thomas Jefferson, and was first ascended by E. C. Cross and R. L. Farmer in 1888. It sits atop an area of crustal melting, and was produced by the subduction of the oceanic Juan de Fuca tectonic plate under the continental North American tectonic plate, forming about 730,000 years ago.
context_section_description: Mount Jefferson lies in the temperate maritime climate of Western Oregon. The Cascades absorb east-moving moisture, causing warm and dry summers. Winters show higher precipitation levels, especially at higher elevations, averaging 140 to 160 inches (3,500 to 4,000 mm) at peak altitudes and consisting mostly of snow. Moving east, annual precipitation levels decrease from 98 inches (2,500 mm) to lower than 16 inches (400 mm).
  When Little Ice Age glaciers retreated during the 20th century, water filled in the spaces left behind, forming moraine-dammed lakes, which are more common in the Mount Jefferson Wilderness and the nearby Three Sisters Wilderness than anywhere else in the contiguous United States. A number of these lakes breached during the 20th century and inundated Jefferson Park and the Jefferson Creek drainage under Waldo Glacier. These breach events yielded floods and small lahars (volcanically induced mudslides, landslides, and debris flows). The flood on August 21, 1934, at a lake formed near Whitewater Glacier, created a debris flow that reached the Whitewater River drainage and buried parts of Jefferson Park in 1 to 8 feet (0.30 to 2.44 m) of debris; another event took place in 1957, but was poorly documented.
  Mount Jefferson has 35 snow and ice features, including four named glaciers: Whitewater, Jefferson Park, Russell, and Waldo. These features, for the most part on the northern, eastern, and southeastern parts of Mount Jefferson, span elevations from 6,158 to 8,189 feet (1,877 to 2,496 m) and cover an area of 2.1 square miles (5.5 km²). The volcano, like much of the Oregon Cascades, was likely covered by an ice cap during the Pleistocene, with the glaciers at their peak size between 25,000 and 20,000 years ago. In recent years, the glaciers have retreated to form lateral moraines; Whitewater Glacier, for example, shrunk from 5 miles (8.0 km) in width and 1 to 2 miles (1.6 to 3.2 km) in length to 1.9 miles (3.1 km) in width and a length of 0.62 miles (1 km). During the 20th century, scientists thought they had identified a new glacier, which they named Milk Creek Glacier, but later studies established that it was an artifact of stagnant ice that had been hidden by debris, and it is no longer considered its own distinct feature.
  Other geographic features at Jefferson include rock outcrops, steep talus slopes, conifer forests, and alpine meadows. Additionally, a number of rivers drain Mount Jefferson. The northern and northwestern slopes feed the South Fork Breitenbush River, which flows into Detroit Lake, and the eastern side of Detroit Lake also receives water from Whitewater Creek, Russell Creek, and Milk Creek, which flow from the western flank of Mount Jefferson. The Whitewater Glacier and the northeastern side of the volcano drain into the Whitewater River, and Shitike Creek flows between Mount Jefferson and Olallie Butte before reaching the Deschutes River. Both Jefferson and Parker Creeks receive water from Jefferson's southeastern slopes, then join the Metolius River.
  Wildfires occur within the wilderness area at Mount Jefferson. In the late summer to early fall of 2017, the Whitewater and Little Devil fires occurred. While the Little Devil fire covered 485 acres (1.96 km²), the Whitewater fire reached more than 10,000 acres (40 km²) in area, provoking the use of amphibious aircraft and causing trail closures. As a result of the Whitewater fire, officials closed the Mount Jefferson Wilderness during the solar eclipse of August 21, 2017.
caption: A view of Mount Jefferson from Russell Lake in 1934
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image ExifOffset": "90", "EXIF ExifImageWidth": "674", "EXIF ExifImageLength": "524"}