|Three Fingered Jack|
|Elevation||7,844 ft (2,391 m) NAVD 88 |
|Prominence||756 m (2,480 ft)|
|Coordinates||44°28′44″N121°50′35″W / 44.478965122°N 121.843058797°W Coordinates: 44°28′44″N121°50′35″W / 44.478965122°N 121.843058797°W |
|Topo map||USGS Three Fingered Jack|
|Age of rock||older than 200,000 years|
|Mountain type||Summit, Shield volcano|
|Volcanic arc||Cascade Volcanic Arc|
|First ascent||1923 by E. McNeal and party |
Three Fingered Jack is a summit of a shield volcano of the Cascade Range in the U.S. state of Oregon. Formed during the Pleistocene epoch, the mountain consists mainly of basaltic andesite lava and was heavily glaciated in the past. While other Oregon volcanoes that were heavily glaciated—such as Mount Washington and Mount Thielsen—display eroded volcanic necks, Three Fingered Jack's present summit is a comparatively narrow ridge of loose tephra supported by a dike only 10 feet (3.0 m) thick on a generally north–south axis. Glaciation exposed radiating dikes and plugs that support this summit. The volcano has long been inactive and is highly eroded.
Three Fingered Jack has diverse flora, fauna, and fungi. The Molala people, one of the indigenous groups in the northwestern United States, historically inhabited the area around the volcano. Not much is known about Molala culture, other than that the group fished for salmon and collected berries, fruits, obsidian, and dried herbs. David Douglas was the first person of non-indigenous descent to reach the area in 1825, followed by Peter Skene Ogden the following year. The first group to ascend the volcano reached its summit in September 1923. Three Fingered Jack can still be climbed, but climbers can require rescue after becoming disoriented in low visibility conditions.
Three Fingered Jack lies in the U.S. state of Oregon, in Linn  and Jefferson counties.  It has a volume of 2.4 cubic miles (10 km3)  and a summit elevation of 7,844 feet (2,391 m),  [a] with a proximal topographic relief of 1,300 feet (400 m) and a draping relief of 4,600 feet (1,400 m).  [b] Its jagged edifice rises between Mount Jefferson and the Three Sisters volcanic complex.  Three Fingered Jack lies within the Mount Jefferson Wilderness and is only accessible on foot by trails such as the Pacific Crest Trail.  Located about 20 miles (32 km) northwest of the city of Sisters, it is a prominent landmark in the area. 
Lateral and terminal moraines formed on Three Fingered Jack during the last major advance of glacial ice in the area during the Wisconsin glaciation, along with glacial striations, altered vegetation patterns, and lithologies that suggest glacial transport of material.  Jack Glacier (unofficially-named) is the sole glacier remaining on the volcano, located in a shaded cirque on the northeast side.   The glacier resides at an unusually low altitude for the central Oregon Cascades it is protected by tall ridges to the south and west.  Jack Glacier has an area of 2.5 acres (1.0 ha), though historically it has reached estimated areas of up to 32 acres (13 ha).  It is likely stagnant.  During the Little Ice Age, which spanned roughly 1350 to 1850, the glacier produced moraines with heights close to 200 feet (61 m),  which are dotted with 1⁄2 to 1 foot (0.15 to 0.30 m) of ash from the Sand Mountain cinder cone chain and 1 foot (0.30 m) of ash from the Blue Lake Crater cinder cone. 
The moraine for Jack Glacier dammed a lake with a volume of 940,000 cubic feet (26,500 m3), a surface area of 65,900 square feet (6,120 m2), and a maximum depth of 26 feet (8 m).  This lake was documented in 1937, although it did not appear on United States Geological Survey topographic maps made during the 1920s.  The lake sits precariously;  moraines on the volcano are steep, unstable, and populated with boulders.  Before September 1960, there was a partial breach of this moraine-dammed lake that covered an area of 12,000 square metres (3.0 acres) near the moraine's base.  Since 1960, there have been at least three incidents in which moraine-dammed lakes on the volcano have caused floods down the slopes,  including a significant flood and debris flow in 2012.  Local soil is thin, and it has been buried by a layer of weathered Holocene tephra from Three Fingered Jack, which has a maximum thickness of 3.3 feet (1 m). 
Douglas fir, Alpine fir, blue spruce, mountain hemlock, and bear grass can be found along the volcano and its hiking trails.  Cascade parsley fern grows on Three Fingered Jack between elevations of 6,500 to 7,000 feet (2,000 to 2,100 m).  There are also mountain goats in the surrounding wilderness area. 
Carnivorous animals in the surrounding area include American black bears, coyotes, cougars,   red foxes, raccoons, American martens, stoats (also known as ermines), long-tailed weasels, American minks, North American river otters, and bobcats.  Deer species include Roosevelt elk, black-tailed deer, and mule deer;  insectivores include vagrant shrews, American water shrews, and coast moles.  Bats at Jefferson include little brown bats and silver-haired bats, and American pikas and snowshoe hares are also present.  Rodents such as yellow-bellied marmots, mountain beavers, yellow-pine chipmunks, Townsend's chipmunks, golden-mantled ground squirrels, western gray squirrels, Douglas squirrels, mountain pocket gophers, North American beavers, deer mice, bushy-tailed woodrats, water voles, Pacific jumping mice, and North American porcupines are present. 
Birds nearby include mallards, northern goshawks, sharp-shinned hawks, red-tailed hawks, dusky grouses, grey partridges, killdeers, spotted sandpipers, California gulls, band-tailed pigeons, great horned owls, mountain pygmy owls, common nighthawks, rufous hummingbirds, Northern flickers, pileated woodpeckers, yellow-bellied sapsuckers, hairy woodpeckers, and white-headed woodpeckers.  Other bird species found in the area consist of Eurasian three-toed woodpeckers, willow flycatchers, olive-sided flycatchers, tree swallows, Canada jays, Steller's jays, common ravens, Clark's nutcrackers, black-capped chickadees, mountain chickadees, chestnut-backed chickadees, red-breasted nuthatches, pygmy nuthatches, Eurasian treecreepers, American dippers, wrens, American robins, varied thrushes, hermit thrushes, Townsend's solitaires, golden-crowned kinglets, ruby-crowned kinglets, water pipits, blue-headed vireos, western tanagers, Cassin's finches, gray-crowned rosy finches, pine siskins, red crossbills, green-tailed towhees, dark-eyed juncos, white-crowned sparrows, golden-crowned sparrows, fox sparrows, and Lincoln's sparrows.  Long-toed salamanders, California giant salamanders, rough-skinned newts, tailed frogs, western toads, Pacific tree frogs, northern red-legged frogs, Oregon spotted frogs, pygmy short-horned lizards, common garter snakes, and northwestern garter snakes make up some of the amphibious and reptilian animals in the vicinity. 
Three Fingered Jack is a shield volcano,     [c] and it is part of the group of volcanoes known as Oregon's Matterhorns, whose tall, pinnacle spires resemble the Matterhorn in Switzerland. The volcano (like Mount Thielsen, Mount Bailey, Diamond Peak, and Mount Washington) had a shorter lifespan than larger volcanoes in the Cascade Range, ceasing eruptive activity more than 100,000 years ago.  Three Fingered Jack marks the northernmost point for this group.  South of Mount Jefferson, the High Cascades of Oregon consist of a broad ridge produced by shield volcano activity and eruptions from cinder cones. Vents range from deeply eroded complexes to recently active volcanoes, with most of the region mantled by normally polarized rock produced within the past 730,000 years. 
Three Fingered Jack is part of a group of more than 30 large shield volcanoes and stratovolcanoes that form a segment of Pleistocene-to-Holocene-epoch volcanic vents that produced mafic lava (rich in magnesium and iron).  Three Fingered Jack includes several overlapping cinder cones and composite cones over underlying lava flows from shield volcano activity.  These volcanic edifices and their lava flow deposits cover an area of 34 square miles (88 km2). 
The major edifice, which consists of light gray, basaltic andesite lava flow deposits, sits 1,000 feet (300 m) to the west of the first tephra cone. Variegated pyroclastic rock is embedded among these flows.  Element abundance analysis suggests that lava in the Three Fingered Jack area can be grouped into discrete units based on its source magma chamber, except for the Jorn Lake basalt produced by the underlying shield volcano and basaltic andesite erupted by Three Fingered Jack. Petrological analysis shows high and low pressures for the crystallization of these lava flow deposits, and that basaltic andesite was distinct from basalt due to longer fractionation times. 
Though Three Fingered Jack does not have a high-level conduit-filling volcanic plug, its summit sits atop a pyroclastic cone.  Another cone lies 350 feet (110 m) to the south of the major cone, and there are secondary craters on the sides, as well as radial dikes and volcanic plugs.  Known subfeatures include two shield volcanoes, Maxwell Butte (less eroded than Three Fingered Jack) and Turpentine Peak, which have elevations of 6,230 feet (1,899 m) and 5,794 feet (1,766 m), respectively.  There are six additional known volcanic cones: Duffy Butte, at an elevation of 5,837 feet (1,779 m); Hogg Rock (a tuya), at an elevation of 5,050 feet (1,540 m); Marion Mountain, at an elevation of 5,351 feet (1,631 m); Red Butte, with an elevation of 5,814 feet (1,772 m); and Marion Peak and Saddle Mountain, which do not have elevations listed.  Other shield volcanoes and cinder cones that were active during the Pleistocene epoch occur to the northwest and southwest. 
The volcano has a long ridge that trends from north to south. It is highly eroded;   shaped like a sawtooth, it consists of tephra deposits supported by a vertical dike with a thickness of 10 feet (3.0 m). Erosion has been so extensive that climbers claim that the summit moves in the wind.  During the Pleistocene epoch, glaciers exposed its inner contents, providing evidence for its eruptive history.  Though it has not been dated by radiometric approaches, the volcano is likely between 500,000 and 250,000 years old,  and has been carved out by at least three glacial periods. 
Three Fingered Jack has an eruptive history similar to many High Cascade volcanoes.  The first activity was the formation of a pyroclastic cone over shield volcanoes. Later eruptions formed a main volcanic cone from lava flows and more pyroclastic rock. There are dikes that radiate from a micronorite plug, which deformed tephra in the surrounding strata. The northern and southern flanks of Three Fingered Jack feature lava flows made of olivine and augite basalt. 
Three Fingered Jack is estimated to be between 500,000 and 250,000 years old.  It underwent more explosive eruptions as its eruptive history progressed, generating large amounts of tephra which created a loose, unconsolidated summit and upper cone. Lava flows near the summit have an average thickness of 3 feet (0.91 m). Secondary volcanic craters produced lava flows and pyroclastic material, which traveled both north and south of the volcano. Cone-building eruptions ceased before the Pleistocene epoch's glacial period, allowing the expanded glacial cover to remove most of the cone, especially on the eastern and northeastern sides. 
During the ongoing Holocene epoch, there has been volcanic activity between the Three Sisters volcanoes and Three Fingered Jack. Such eruptive episodes have produced tephra and lava flows that cover several hundred square kilometers in the region. These eruptions occurred after the climactic eruption of Mount Mazama, which took place roughly 6,600 years ago. 
The Molala people traditionally inhabited the surrounding area. The Molala fished for salmon and collected berries, fruits, obsidian, and dried herbs. Their culture was not well documented.  The first person of non-indigenous descent to reach the area was David Douglas in 1825, followed by Peter Skene Ogden the following year. 
Sources disagree about the affiliation of the mountain's first ascenders, some calling them "the Boys from Bend,"  others saying they were members of the Mazamas mountaineering club.  Nonetheless, a source written by one of these first ascenders clearly states who was in the party and when they climbed. Ervin McNeal, Phil Philbrook, Armin Furrer, Wilbur Watkins, Leo Harryman, and Ronald Sellars were the first to ascend Three Fingered Jack on September 3, 1923. 
The origins of Three Fingered Jack's name remain unclear.  One account claims that the volcano received its name from Joaquin Murrieta, a gold miner and vaquero during the California Gold Rush also known as Three Fingered Jack.  Others allege that the volcano was named after a trapper with less than five fingers on one of his hands. 
Hikers can see Three Fingered Jack on trails surrounding the mountain. The Canyon Creek Meadows hiking trail begins at Jack Lake, progresses through the Mount Jefferson Wilderness, and runs for about 4.5 miles (7.2 km). It has an elevation gain of 400 feet (120 m), and is accessible to children and families. An additional connected hiking trail runs for another 3 miles (4.8 km) up the rocky glacial washout plain adjacent to the volcano, becoming steeper as it approaches Three Fingered Jack and gaining 1,400 feet (430 m) in elevation.  The base can also be reached on Pacific Crest Trail which runs for 11.6 miles (18.7 km) round trip and offers views of the volcano and its summit lake.  Moreover, the Three Fingered Jack loop trail runs for 20.5 miles (33.0 km) around the volcano, gaining 3,300 feet (1,000 m) in elevation. 
When Three Fingered Jack's face becomes foggy, climbers have become disoriented due to the low visibility conditions of climbing the mountain, requiring rescue.  
The summit can be quite dangerous due steep cliffs and poor rock quality which can result in footing and hand holds giving way without warning. One such event occurred on July 19, 2020, resulting in the death of a hiker attempting to reach the summit.  
Mount Bachelor, formerly named Bachelor Butte, is a dormant 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 (24 km) 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 extinct or just inactive.
Newberry Volcano is a large active shield-shaped stratovolcano located about 20 miles (32 km) south of Bend, Oregon, United States, 35 miles (56 km) east of the major crest of the Cascade Range, within the Newberry National Volcanic Monument. Its highest point is Paulina Peak. The largest volcano in the Cascade Volcanic Arc, Newberry has an area of 1,200 square miles (3,100 km2) when its lava flows are taken into account. From north to south, the volcano has a length of 75 miles (121 km), with a width of 27 miles (43 km) and a total volume of approximately 120 cubic miles (500 km3). It was named for the geologist and surgeon John Strong Newberry, who explored central Oregon for the Pacific Railroad Surveys in 1855. The surrounding area has been inhabited by Native American populations for more than 10,000 years.
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.
Mount Thielsen, or Big Cowhorn, is an extinct shield volcano in the Oregon High Cascades, near Mount Bailey. Because eruptive activity ceased 250,000 years ago, glaciers have heavily eroded the volcano's structure, creating precipitous slopes and a horn-like peak. The spire-like shape of Thielsen attracts lightning strikes and creates fulgurite, an unusual mineral. The prominent horn forms a centerpiece for the Mount Thielsen Wilderness, a reserve for recreational activities such as skiing and hiking. Thielson is one of Oregon's Matterhorns.
Mount Mazama is a complex volcano in the state of Oregon, United States, in a segment of the Cascade Volcanic Arc and Cascade Range. Most of the mountain collapsed following a major eruption approximately 7,700 years ago. The volcano is in Klamath County, in the southern Cascades, 60 miles (97 km) north of the Oregon–California border. Its collapse, due to the eruption of magma emptying the underlying magma chamber, formed a caldera that holds Crater Lake. The mountain is in Crater Lake National Park. Mount Mazama originally had an elevation of 12,000 feet (3,700 m), but following its climactic eruption this was reduced to 8,157 feet (2,486 m). Crater Lake is 1,943 feet (592 m) deep, the deepest freshwater body in the US and the second deepest in North America after Great Slave Lake in Canada.
Mount Washington is a deeply eroded volcano in the Cascade Range of Oregon. It lies within Deschutes and Linn counties and is surrounded by the Mount Washington Wilderness area.
Belknap Crater is a shield volcano in the Cascade Range in the U.S. state of Oregon. Located in Linn County, it is associated with lava fields and numerous subfeatures including the Little Belknap and South Belknap volcanic cones. It lies north of McKenzie Pass and forms part of the Mount Washington Wilderness. Belknap is not forested and most of its lava flows are not vegetated, though there is some wildlife in the area around the volcano, as well as a number of tree molds formed by its eruptive activity.
Mount McLoughlin is a dormant steep-sided stratovolcano, or composite volcano, in the Cascade Range of southern Oregon and within the United States Sky Lakes Wilderness. It is one of the volcanic peaks in the Cascade Volcanic Arc, within the High Cascades sector. A prominent landmark for the Rogue River Valley, the mountain is north of Mount Shasta, and south-southeast of Crater Lake. It was named around 1838 after John McLoughlin, a Chief Factor for the Hudson's Bay Company. Mount McLouglin's prominence has made it a landmark to Native American populations for thousands of years.
Indian Heaven is a volcanic field in Skamania County in the state of Washington, in the United States. Midway between Mount St. Helens and Mount Adams, the field dates from the Pleistocene to the early Holocene epoch. It trends north to south and is dominated by six small shield volcanoes; these shields are topped by small spatter and cinder cones, and the field includes a number of subglacial volcanoes and tuyas. The northernmost peak in the field is Sawtooth Mountain and the southernmost is Red Mountain; its highest point is Lemei Rock at an elevation of 5,925 feet (1,806 m).
Broken Top is a glacially eroded complex stratovolcano. It lies in the Cascade Volcanic Arc, part of the extensive Cascade Range in the U.S. state of Oregon. Located southeast of the Three Sisters peaks, the volcano, residing within the Three Sisters Wilderness, is 20 miles (32 km) west of Bend, Oregon in Deschutes County. Eruptive activity stopped roughly 100,000 years ago, and currently, erosion by glaciers has reduced the volcano's cone to where its contents are exposed. There are two named glaciers on the peak, Bend and Crook Glacier.
The Three Sisters are closely spaced volcanic peaks in the U.S. state of Oregon. They are part of the Cascade Volcanic Arc, a segment of the Cascade Range in western North America extending from southern British Columbia through Washington and Oregon to Northern California. Each more than 10,000 feet (3,000 m) in elevation, they are the third-, fourth- and fifth-highest peaks in Oregon. Located in the Three Sisters Wilderness at the boundary of Lane and Deschutes counties and the Willamette and Deschutes national forests, they are about 10 miles (16 km) south of the nearest town, Sisters. Diverse species of flora and fauna inhabit the area, which is subject to frequent snowfall, occasional rain, and extreme temperature variation between seasons. The mountains, particularly South Sister, are popular destinations for climbing and scrambling.
Black Butte is an extinct stratovolcano in the U.S. state of Oregon. Located in Jefferson County, it is part of Deschutes National Forest. Black Butte forms part of the Cascade volcanic arc. The butte lies just south of the Metolius Springs, which merge to form the headwaters of the Metolius River. The Metolius River's basin sustains a wide array of plant life, large and small mammals, and more than 80 bird species.
Diamond Peak is a volcano in Klamath and Lane counties of central Oregon in the United States. It is a shield volcano, though it might also be considered a modest stratocone. Diamond Peak forms part of the Cascade Volcanic Arc, a segment of the Cascade Range in western North America extending from southern British Columbia through Oregon to Northern California. Reaching an elevation of 8,748 feet (2,666 m), the mountain is located near Willamette Pass in the Diamond Peak Wilderness within the Deschutes and Willamette national forests. Surrounded by coniferous forest and visible in the skyline from foothills near Eugene, Diamond Peak offers a few climbing routes and can be scrambled. Diamond Peak is one of Oregon's Matterhorns.
West Crater is a small lava dome with associated lava flows in southern Washington, United States. Located in Skamania County, it rises to an elevation of 4,131 feet (1,259 m), and forms part of the Cascade Volcanic Arc. It is also part of the Marble Mountain-Trout Creek Hill volcanic field, a little-known Quaternary volcanic field in the southern Cascades of Washington state. The area can be hiked, and can be accessed by roads in the Gifford Pinchot National Forest.
Big Cave is a small shield volcano located in northern California in the Cascade Volcanic Arc of the Pacific Northwest. With an elevation listed at either 4,130 feet (1,260 m) or 4,131 feet (1,259 m), it is the product of subduction of several tectonic plates under the North American Plate, which continues at a rate of 4 centimetres (1.6 in) each year.
Olallie Butte is a steep-sided shield volcano in the Cascade Range of the northern part of the U.S. state of Oregon. It is the largest volcano and highest point in the 50-mile (80 km) distance between Mount Hood and Mount Jefferson. Located just outside the Olallie Scenic Area, it is surrounded by more than 200 lakes and ponds fed by runoff, precipitation, and underground seepage, which are popular spots for fishing, boating, and swimming. The butte forms a prominent feature in the Mount Jefferson region and is usually covered with snow during the winter and spring seasons.
Black Crater is a shield volcano in the Western Cascades in Deschutes County, Oregon. Located near McKenzie Pass, the volcano has a broad conical shape with gentle slopes. The volcano likely formed during the Pleistocene and has not been active within the last 50,000 years. Eruptive activity at the volcano produced mafic lava flows made of basaltic andesite and olivine basalt; it also formed a number of cinder cones. A normal fault occurs on the western side of the volcano, trending north–south. The volcano has been eroded by glaciers, which carved a large cirque into the northeastern flank of the mountain, forming its current crater.
Pelican Butte is a steep-sided dormant shield volcano in the Cascade Range of southern Oregon. It is located 28 miles (45 km) due south of Crater Lake and 12 miles (19 km) northeast of Mount McLoughlin, and rises over 3,800 feet (1,200 m) directly above the shore of Upper Klamath Lake. Ice age glaciers carved a large cirque into the northeast flank of the mountain, forming a steep bowl which is popular in winter with backcountry skiers and snowmobilers. Several proposals have been made over the last few decades for ski area development on the northeast flanks, but none of the proposals has obtained the regulatory approval from the United States Forest Service necessary to proceed with construction. If the ski area is ever built, its skiable vertical of over 3,800 feet (1,200 m) would be the largest in Oregon exceeding the 3,590 feet (1,090 m) of Timberline Lodge ski area on Mount Hood.
Blue Lake Crater is a maar, or a broad, low-relief volcanic crater, in the U.S. state of Oregon. Located in Jefferson County, it consists of three overlapping craters, which hold Blue Lake. The drainage basin for Blue Lake has very steep, forested slopes and is mostly part of the explosion crater left by the volcano's eruption. The volcano lies within the Metolius River basin, which supports a wide array of plant life, large and small mammals, and more than 80 bird species. In 2009, Governor of Oregon Ted Kulongoski signed a bill designating the Metolius River basin as an area of critical concern, preventing large-scale development on the land and protecting its wildlife.
The Sand Mountain Volcanic Field is a volcanic field in the upper McKenzie River watershed, located in the United States in Oregon. Part of the Cascade Volcanic Arc, it lies southwest of Mount Jefferson and northwest of Belknap Crater and Mount Washington. Its highest elevation is 5,463 feet (1,665 m).