Diamond Peak Wilderness
The Diamond Peak Wilderness is a wilderness area straddling the Cascade crest and includes the Diamond Peak volcano. It is located within two National Forests - the Willamette National Forest on the west and the Deschutes National Forest on the east. On February 5, 1957, the Forest Service established the 36,637-acre Diamond Peak Wild Area. Upon passage of the federal Wilderness Act in 1964 it was reclassified as wilderness. With the passage of the Oregon Wilderness Act of 1984, Diamond Peak Wilderness increased in size to its present 52,337 acres. At 8,744 feet, Diamond Peak is the most prominent peak in the wilderness, followed by Mount Yoran at 7,138 feet and Lakeview Mountain at 7,057 feet. Diamond Peak is a shield volcano formed as the entire Cascade Range was undergoing volcanic activity and uplift. Glaciers carved the large volcanic peak, when they receded, the bulk of the mountain remained, with snowfields near the summit and dozens of small lakes surrounding the peak; these lakes range from one to 28 acres in size.
14 miles of the Pacific Crest National Scenic Trail pass through this wilderness. Another 38 miles of trail, including the 10-mile Diamond Peak Trail, stretches the length of the west side of the peak. Nearly the entire Diamond Peak Wilderness is covered with mixed stands of mountain hemlock and western white pine, silver and other true firs. Alpine flowers, including varieties of mimulus, lupine, penstemon and Indian paintbrush, are common along trails, lake shores, streams and in the meadows. Huckleberry and dwarf manzanita are common in the dense underbrush; the Diamond Peak Wilderness is home to black-tailed deer, mule deer, elk. In winter, the mule deer migrate eastward out of the wilderness to the sage desert, while black-tailed deer and elk drop down the west slope. Black bear and small mammals including marmots, snowshoe rabbits, pine martens and pikas inhabit the area all year long; the raven, Clark's nutcracker, Oregon jay, water ouzel frequent the forest and streams year-round. Bufflehead and goldeneye ducks nest near the lakes.
Recreational activities in the Diamond Peak Wilderness include hiking, horseback riding, hunting and mountain climbing. Some 125 miles of trails cross the wilderness, including 14 miles the Pacific Crest Trail along the east slope of Diamond Peak. Marie Lake, Divide Lake, Rockpile Lake are popular base camps for the climb up Diamond Peak. Mount Yoran and Lakeview Mountain can be climbed. Winter is popular for cross-country skiing. List of Oregon Wildernesses List of U. S. Wilderness Areas Willamette National Forest - Diamond Peak Wilderness Deschutes & Ochoco National Forests - Diamond Peak Wilderness
Mount Bachelor named Bachelor Butte, is a stratovolcano atop a shield volcano in the Cascade Volcanic Arc and the Cascade Range of central Oregon. Named Mount Bachelor because it "stands apart" from the nearby Three Sisters, it lies in the eastern segment of the central portion of the High Cascades, the eastern segment of the Cascade Range; the volcano lies at the northern end of the 15-mile long Mount Bachelor Volcanic Chain, which underwent four major eruptive episodes during the Pleistocene and the Holocene. The United States Geological Survey considers Mount Bachelor a moderate threat, but Bachelor poses little threat of becoming an active volcano in the near future, it remains unclear whether the volcano is just inactive. The Mount Bachelor ski area has operated on the mountain since 1958, the volcano's summit hosts the Mount Bachelor Observatory. A center of winter recreation, the area offers snowshoeing, snow skiing, snow tubing, dog sledding, among other activities; the summit can be reached by a climbing trail.
Mount Bachelor lies in the Cascade Range, within Deschutes County, in the U. S. state of Oregon. It is located south of the Three Sisters complex volcano, reaches an elevation of 9,068 feet, it rises 3,500 feet with a proximal relief of 2,674 feet. The volcano has a volume of 6.0 cubic miles. Mount Bachelor stands 3 miles southeast of the Tumalo Mountain volcano and 18 miles to the southwest of the city of Bend, in the Deschutes National Forest. Weather varies in the area due to the rain shadow caused by the Cascade Range. Air from the Pacific Ocean rises over the western slopes, which causes it to cool and dump its moisture as rain. Precipitation increases with elevation. Once the moisture is wrung from the air, it descends on the eastern side of the crest, which causes the air to be warmer and drier. On the western slopes, precipitation ranges from 80 to 125 inches annually, while precipitation over the eastern slopes varies from 40 to 80 inches in the east. Temperature extremes reach − 20 to − 30 °F during the winters.
Mount Bachelor joins several other volcanoes in the eastern segment of the Cascade Range known as the High Cascades, which trends north–south. Constructed towards the end of the Pleistocene Epoch, these mountains are underlain by more ancient volcanoes that subsided due to parallel north–south faulting in the surrounding region. Bachelor lies in the eastern segment of the central portion of the High Cascades. Mount Bachelor is the youngest prominent volcano in the Three Sisters area of Oregon, a group of grouped volcanic peaks, in contrast to the typical 40-to-60-mile spacing between volcanoes elsewhere in the Cascades. Among the most active volcanic areas in the Cascades and one of the most densely populated volcanic centers in the world, the Three Sisters region includes peaks such as Belknap Crater, Mount Washington, Black Butte, Three Fingered Jack to the north, Broken Top and Mount Bachelor to the south. Most of the surrounding volcanoes consist of mafic lavas. Mafic magma is less viscous.
The Mount Bachelor volcanic chain, southeast of South Sister, consists of Mount Bachelor, the largest and northernmost volcano of the group, a series of cinder cones, lava flows, three shield volcanoes. The chain runs for 15 miles and encompasses an area of about 100 square miles, trending from north to south, its volcanoes show significant variation in size and shape, ranging from steep cones produced by mild explosive activity to the sloping profiles of shield volcanoes. Volcanic vents within the locale show north–northwest–north–northeast-trending trends, which correspond to normal faults in the region, including one at the Bachelor chain's southern end; the Bachelor chain shows that much of the Quaternary Cascades in Oregon were produced in short bursts of eruptive activity and that mafic shield volcanoes can erupt at equal rates to stratovolcanoes. The volcanoes within the field are fed by compartmentalized magma chambers. A stratovolcano, Mount Bachelor formed between 18,000 and 8,000 years ago.
Bachelor is composed of basalt and basaltic andesite, though its upper volcanic cone formed after its base shield, the two edifices show similar eruptive composition. The mountain has withstood little alteration as a result of glacial erosion besides a small cirque on the northern side of the volcano. Despite the small scale of this erosion, it has extensively altered the northern face of Mount Bachelor, breaking down its lava into fine powder at the glacier terminus, where the terminal moraine resembles dust. However, the volcano's glacier has shrunk in recent decades and may vanish as a result of the warming climate; the volcano's summit has a number of clustered, northwest–southeast-trending vents, which erupted block lava flows made of basalt and andesite and only exhibited minor explosive eruptions, as little tephra can be found near the vents at the summit. There is no summit crater. Lava flows from Mount Bachelor's summit feature phenocrysts including clinopyroxene and plagioclase, with two phases for the clinopyroxene featuring augite and pigeonite
A lava tube is a natural conduit formed by flowing lava which moves beneath the hardened surface of a lava flow. Tubes can drain lava from a volcano during an eruption, or can be extinct, meaning the lava flow has ceased, the rock has cooled and left a long cave. A lava tube is a type of lava cave formed when a low-viscosity lava flow develops a continuous and hard crust, which thickens and forms a roof above the still-flowing lava stream. Tubes form in one of two ways: either by the crusting over of lava channels, or from pāhoehoe flows where the lava is moving under the surface. Lava leaves the point of eruption in channels; these channels tend to stay hot as their surroundings cool. This means they develop walls around them as the surrounding lava cools and/or as the channel melts its way deeper; these channels can get deep enough to crust over, forming an insulating tube that keeps the lava molten and serves as a conduit for the flowing lava. These types of lava tubes tend to be closer to the lava eruption point.
Farther away from the eruption point, lava can flow in an unchanneled, fan-like manner as it leaves its source, another lava tube leading back to the eruption point. Called pāhoehoe flows, these areas of surface-moving lava cool, forming either a smooth or rough, ropy surface; the lava continues to flow this way. At this point, the subsurface lava is still hot enough to break out at a point, from this point the lava begins as a new "source". Lava flows from the previous source to this breakout point as the surrounding lava of the pāhoehoe flow cools; this forms an underground channel. A broad lava-flow field consists of a main lava tube and a series of smaller tubes that supply lava to the front of one or more separate flows; when the supply of lava stops at the end of an eruption or lava is diverted elsewhere, lava in the tube system drains downslope and leaves empty caves. Such drained tubes exhibit step marks on their walls that mark the various depths at which the lava flowed, known as flow ledges or flow lines depending on how prominently they protrude from the walls.
Lava tubes have pāhoehoe floors, although this may be covered in breakdown from the ceiling. A variety of speleothems may be found in lava tubes including a variety of stalactite forms known as lavacicles, which can be of the splash, shark tooth, or tubular variety. Lavacicles are the most common of lava tube speleothems. Drip stalagmites may form under tubular lava stalactites, the latter may grade into a form known as a tubular lava helictite. A runner is a bead of lava, extruded from a small opening and runs down a wall. Lava tubes may contain mineral deposits that most take the form of crusts or small crystals, less as stalactites and stalagmites. Lava tubes can be up to 14–15 metres wide, though are narrower, run anywhere from 1–15 metres below the surface. Lava tubes can be long. A lava tube system in Kiama, consists of over 20 tubes, many of which are breakouts of a main lava tube; the largest of these lava tubes is 2 meters in diameter and has columnar jointing due to the large cooling surface.
Other tubes have radial jointing features. The tubes are infilled due to the low slope angle of emplacement. By far the largest known lava tubes in the Solar System are on Venus. Lunar lava tubes have been discovered and have been studied as possible human habitats, providing natural shielding from radiation. Martian lava tubes are associated with innumerable lava flows and lava channels on the flanks of Olympus Mons. Collapsed lava tubes are visible as chains of pit craters, broad lava fans formed by lava emerging from intact, subsurface tubes are common. Iceland Raufarhólshellir Surtshellir – For a long time, this was the longest known lava tube in the world. Kenya Leviathan Cave – At 12.5 kilometres, it is the longest lava tube in Africa. Portugal Gruta das Torres – Lava tube system of the Azores. South Korea Manjang Cave – more than 8 kilometers long, located in Jeju Island, is a popular tourism spot. Spain Cueva de los Verdes – Lava tube system. Lanzarote, Canary Islands. United States Kazumura Cave, Hawaii – Not only the world's most extensive lava tube, but at 40.7 miles has the greatest linear extent of any cave known.
Lava River Cave in Oregon's Newberry National Volcanic Monument – Newberry National Volcanic Monument Ape Cave, Washington – May be the third longest lava tube in the continental United States. Caving – Recreational pastime of exploring cave systems Geology of the Moon – Structure and composition of the Moon Lava cave – Cave formed in volcanic rock one formed via volcanic processes Mars habitat Speleology – Science of cave and karst systems Speleothem – A structure formed in a cave by the deposition of minerals from water
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are sometimes described as lava; the molten rock is formed in the interior of some planets, including Earth, some of their satellites, though such material located below the crust is referred to by other terms. A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption; when it has stopped moving, lava solidifies to form igneous rock. The term lava flow is shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic and shear thinning properties. Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows; the word lava comes from Italian, is derived from the Latin word labes which means a fall or slide.
The first use in connection with extruded magma was in a short account written by Francesco Serao on the eruption of Vesuvius in 1737. Serao described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of the volcano following heavy rain; the composition of all lava of the Earth's crust is dominated by silicate minerals feldspars, pyroxenes, amphiboles and quartz. Igneous rocks, which form lava flows when erupted, can be classified into three chemical types: felsic and mafic; these classes are chemical, the chemistry of lava tends to correlate with the magma temperature, its viscosity and its mode of eruption. Felsic or silicic lavas such as rhyolite and dacite form lava spines, lava domes or "coulees" and are associated with pyroclastic deposits. Most silicic lava flows are viscous, fragment as they extrude, producing blocky autobreccias; the high viscosity and strength are the result of their chemistry, high in silica, potassium and calcium, forming a polymerized liquid rich in feldspar and quartz, thus has a higher viscosity than other magma types.
Felsic magmas can erupt at temperatures as low as 650 to 750 °C. Unusually hot rhyolite lavas, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States. Intermediate or andesitic lavas are lower in aluminium and silica, somewhat richer in magnesium and iron. Intermediate lavas form andesite domes and block lavas, may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, commonly hotter, they tend to be less viscous. Greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and a greater tendency to form phenocrysts. Higher iron and magnesium tends to manifest as a darker groundmass, occasionally amphibole or pyroxene phenocrysts. Mafic or basaltic lavas are typified by their high ferromagnesian content, erupt at temperatures in excess of 950 °C. Basaltic magma is high in iron and magnesium, has lower aluminium and silica, which taken together reduces the degree of polymerization within the melt.
Owing to the higher temperatures, viscosities can be low, although still thousands of times higher than water. The low degree of polymerization and high temperature favors chemical diffusion, so it is common to see large, well-formed phenocrysts within mafic lavas. Basalt lavas tend to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent; the thickness of a basalt lava on a low slope, may be much greater than the thickness of the moving lava flow at any one time, because basalt lavas may "inflate" by supply of lava beneath a solidified crust. Most basalt lavas are of pāhoehoe types, rather than block lavas. Underwater, they can form pillow lavas, which are rather similar to entrail-type pahoehoe lavas on land. Ultramafic lavas such as komatiite and magnesian magmas that form boninite take the composition and temperatures of eruptions to the extreme. Komatiites contain over 18% magnesium oxide, are thought to have erupted at temperatures of 1,600 °C.
At this temperature there is no polymerization of the mineral compounds, creating a mobile liquid. Most if not all ultramafic lavas are no younger than the Proterozoic, with a few ultramafic magmas known from the Phanerozoic. No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce magnesian magmas; some lavas of unusual composition have erupted onto the surface of the Earth. These include: Carbonatite and natrocarbonatite lavas are known from Ol Doinyo Lengai volcano in Tanzania, the sole example of an active carbonatite volcano. Iron oxide lavas are thought to be the source of the iron ore at Kiruna, Sweden which formed during the Proterozoic. Iron oxide lavas of Pliocene age occur at the El Laco volcanic complex on the Chile-Argentina border. Iron oxide lavas are thought to be the result of immiscible separation of iron oxide magma from a parental magma of calc-alkaline or alkaline composition. Sulfur lava flows up to 250 metres 10 metres wide occur at Lastarria volcano, Chile.
They were formed by the melting of sulfur deposits at temperatures as low as 113 °C
John Day Fossil Beds National Monument
John Day Fossil Beds National Monument is a U. S. National Monument in Wheeler and Grant counties in east-central Oregon. Located within the John Day River basin and managed by the National Park Service, the park is known for its well-preserved layers of fossil plants and mammals that lived in the region between the late Eocene, about 45 million years ago, the late Miocene, about 5 million years ago; the monument consists of three geographically separate units: Sheep Rock, Painted Hills, Clarno. The units cover a total of 13,944 acres of semi-desert shrublands, riparian zones, colorful badlands. About 210,000 people visited the park in 2016 to engage in outdoor recreation or to visit the Thomas Condon Paleontology Center or the James Cant Ranch Historic District. Before the arrival of Euro-Americans in the 19th century, the John Day basin was frequented by Sahaptin people who hunted and gathered roots and berries in the region. After road-building made the valley more accessible, settlers established farms, a few small towns along the river and its tributaries.
Paleontologists have been unearthing and studying the fossils in the region since 1864, when Thomas Condon, a missionary and amateur geologist, recognized their importance and made them known globally. Parts of the basin became a National Monument in 1975. Averaging about 2,200 feet in elevation, the monument has a dry climate with temperatures that vary from summer highs of about 90 °F to winter lows below freezing; the monument has more than 80 soil types that support a wide variety of flora, ranging from willow trees near the river to grasses on alluvial fans to cactus among rocks at higher elevations. Fauna include more than 50 species of migratory birds. Large mammals like elk and smaller animals such as raccoons and voles frequent these units, which are populated by a wide variety of reptiles, fish and other creatures adapted to particular niches of a mountainous semi-desert terrain; the John Day Fossil Beds National Monument consists of three separated units—Sheep Rock, Painted Hills, Clarno—in the John Day River basin of east-central Oregon.
Located in rugged terrain in the counties of Wheeler and Grant, the park units are characterized by hills, deep ravines, eroded fossil-bearing rock formations. To the west lies the Cascade Range, to the south the Ochoco Mountains, to the east the Blue Mountains. Elevations within the 13,944-acre park range from 2,000 to 4,500 feet; the Clarno Unit, the westernmost of the three units, consists of 1,969 acres located 18 miles west of Fossil along Oregon Route 218. The Painted Hills Unit, which lies about halfway between the other two, covers 3,132 acres, it is situated about 9 miles northwest of Mitchell along Burnt Ranch Road, which intersects U. S. Route 26 west of Mitchell; these two units are within Wheeler County. The remaining 8,843 acres of the park, the Sheep Rock Unit, are located along Oregon Route 19 and the John Day River upstream of the unincorporated community of Kimberly; this unit is in Grant County, although a small part extends into Wheeler County. The Sheep Rock Unit is further subdivided into the Mascall Formation Overlook, Picture Gorge, the James Cant Ranch Historic District, Cathedral Rock, Blue Basin, the Foree Area.
Some of these are separated from one another by farms and other parcels of land that are not part of the park. The park headquarters and main visitor center, both in the Sheep Rock Unit, are 122 miles northeast of Bend and 240 miles southeast of Portland by highway; the shortest highway distances from unit to unit within the park are Sheep Rock to Painted Hills, 45 miles. The John Day River, a tributary of the Columbia River, flows west from the Strawberry Mountains before reaching the national monument, it turns north between the Mascall Formation Overlook and Kimberly, where the North Fork John Day River joins the main stem. Downstream of Kimberly, the river flows west to downstream of the unincorporated community of Twickenham, north thereafter. Rock Creek enters the river at the north end of Picture Gorge. Bridge Creek passes through Mitchell north along the eastern edge of the Painted Hills Unit to meet the John Day downstream of Twickenham. Intermittent streams in the Clarno Unit empty into Pine Creek, which flows just beyond the south edge of the unit and enters the John Day upstream of the unincorporated community of Clarno.
Early inhabitants of north-central Oregon included Sahaptin-speaking people of the Umatilla and Warm Springs tribes as well as the Northern Paiutes, speakers of a Uzo-Aztecan language. All were hunter-gatherers competing for resources such as elk and salmon. Researchers have identified 36 sites of related archeological interest, including rock shelters and cairns, in or adjacent to the John Day Fossil Beds National Monument. Most significant among the prehistoric sites are the Picture Gorge pictographs, consisting of six panels of rock art in the canyon at the south end of the Sheep Rock Unit; the art is of undetermined origin and age but is "centuries old". The John Day basin remained unexplored by non-natives until the mid-19th century. Lewis and Clark noted but did not explore the John Day River while traveling along the Columbia River in 1805. John Day, for whom the river is named visited only its confluence with the Columbia in 1812. In 1829, Peter Skene Ogden, working for the Hudson's Bay Company, led a company of explorers and fur trappers along the river through what would
Fremont National Forest
The Fremont-Winema National Forest of south central Oregon is a mountainous region with a rich geological, ecological and historical history. Founded in 1908, the Fremont National Forest was protected as the Goose Lake Forest Reserve in 1906; the name was soon changed to Fremont National Forest, named after John C. Frémont, who explored the area for the United States Army Corps of Engineers in 1843, it absorbed part of Paulina National Forest on July 19, 1915. In 2002, it was administratively combined with the Winema National Forest as the Fremont–Winema National Forests; the Fremont National Forest is the eastern portion of the Fremont-Winema National Forest, which combined comprises a significant portion of south-central Oregon. Yamsay Mountain is located in the extreme north-northwest of the forest region; the Winema portion includes the eastern slopes of the Cascade Mountains. The Fremont portion includes an area that begins on the shores of Klamath Marsh in the west, Hagger Mountain in the north, Winter Rim on the east, down to the California border between near Lakeview, Oregon.
This area of Oregon region is nicknamed the ‘pumice plains’, referring to the area having borne the brunt of tephra deposition during the eruption of Mount Mazama in 7,620 BP. The climate is drier on the east side of the Cascades, resulting in a rainshadow effect; this difference in precipitation between the lower and higher elevations of forested areas spans two Köppen climate classifications. The majority of the Fremont is Csb: warm summer Mediterranean, whereas elevations of 7,000 feet and higher are designated as Dsc: dry summer subarctic. Precipitation in the form of winter rains and snow pack feed watersheds that include perennial and annual creeks, fen marshes, small lakes. Perennial rivers include the Chewaucan, Sprague and Sycan; the landscape is flat and rolling, although there are some high peaks that include Yamsay Mountain at 8,196 feet above sea level, 8,370 foot Gearhart Mountain. Both are volcanic in origin but formed during events separate from what formed the nearby Cascade Range.
The volcanoes of the Fremont Forest are older than the Cascades and were a result of tectonic sheering stretching the crust thin which allowed mantle magma to emerge at the surface. Crustal stretching continued through the late Miocene resulting in uplifted fault blocking of what was flat basalt landscapes, creating into towering scarp- mountains that are sloped on one side and terminate into a sharp scarp face on the other; the east portion of the Fremont Forest region is like this, sloping to the west and terminating in a sheer scarp face along the Summer Lake sub-basin. Human presence in the Fremont region extends back thousands of years. Physical evidence of this comes from the Paisley Caves Fort Rock Cave, more Connolly Caves; these sites are within 10 to 20 miles from the Fremont Forest boundary. Further archaeological evidence of human activity can be found at Carlon Village and Picture Rock Pass, many more smaller house rings and artifact scatters throughout the area. Through clear cultural relationships seen in the artifact record, as well as legends and oral knowledge tying them to this place, the decedents of these early people are the Klamath.
The Paiute and Modoc have a long and rich cultural connection to the Fremont Forest. Native people were moved out of their traditional territories through the late 1800s into the mid-1900s as a response to Euro-American settlers in the region that were attracted to rich forest resources and ranching possibilities; the exception was Yamsay Mountain which remained part of the 1901 Klamath Reservation until 1911 when it became listed as part of the Paulina National Forest and was ceded to the Fremont National Forest in 1913. The Klamath tried to recover their previous lands, but in 1954 the Klamath Termination Act meant that the tribe's remaining 525,700 acres of former Indian reservation lands all within the Fremont Forest region, were placed under National Forest administration under the 1953 House Concurrent Resolution 108. Klamath tribal designation was restored in 1986. Euro-American traders began entering the Klamath area at some point between 1825 and 1827, where they worked as trappers for the Hudson's Bay Company.
The Fremont National Forest was established in 1908 and was named for Captain John C. Fremont, sent to explore the area in 1843. After trade routes inland and to the Pacific were opened up in 1846, Fort Klamath was built in 1863 and the Klamath reservation was established. In the beginning the Klamath were able to keep Yamsay Mountain in their territory, but vast economic opportunities present was too much for the federal government to resist. Trappers may have begun the early movements of Euro-Americans into the area, but it was the harvesting of old growth ponderosa pine timber, the real draw in the 19th century. Ecological damage done by excessive logging was exacerbated by the introduction of sheep and cattle ranching, complete fire suppression, other activities which remain visible on the landscape to this day; the Fremont Forest region is listed as part of the Mazama ecoregion due to high amounts of Mazama tephra covering the landscape as a result of its catastrophic eruption 7,620 years ago that resulted in the formation of Crater Lake.
Fremont ecology is at once fragile and robust, with dominant trees including ponderosa and lodgepole
Mount Thielsen Wilderness
The Mount Thielsen Wilderness is a wilderness area located on and around Mount Thielsen in the southern Cascade Range of Oregon in the United States. It is located within the Deschutes and Fremont–Winema national forests, it comprises 55,100 acres. The Mount Thielsen Wilderness ranges in elevation from 5,000 feet above sea level to 9,182 feet at the summit of Mount Thielsen; the mountain was carved by glacial activity and is sometimes referred to as the "Lightning Rod of the Cascades." To the south of the wilderness is Crater Lake National Park. The rest of the wilderness consists of flat and moderately rolling hills, which change to steep and dissected ridges toward the crest of the Cascade Mountains. Popular lakes in the wilderness include Maidu Lake; the headwaters of the Wild and Scenic North Umpqua River are at Maidu. Lodgepole pine dominate the lower portion of the Mount Thielsen Wilderness. A forest of mountain hemlock and fir grows at higher elevations, up to the timberline at about 7,200 feet.
Primary recreational activities in the Mount Thielsen Wilderness include camping, wildlife watching, rock climbing. There are 78 miles of hiking trails in the wilderness, including a 26-mile portion of the Pacific Crest Trail. List of Oregon Wildernesses List of U. S. Wilderness Areas List of old growth forests Wilderness Act Mt. Thielsen Wilderness - Deschutes National Forest Mt. Theilsen Wilderness - Umpqua National Forest Mt. Thielsen Wilderness - Fremont–Winema National Forest