Hogg Rock is a

tuya A tuya is a flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet. They are rare worldwide, being confined to regions which were covered by glaciers and had active volcanism during the same period. As lava ...

volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

and lava dome in the Cascade Range of northern

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

, United States, located close to Santiam Pass. Produced by magma with an intermediate

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predo ...

composition, it has steep slopes and thick glassy margins. Hogg Rock exhibits normal magnetic polarity and is probably about 80,000 years old. Hogg Rock lies south of

Three Fingered Jack 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 o ...

and north of Hayrick Butte, a somewhat larger tuya of similar age and composition. A tuya is a type of subglacial volcano, formed when lava erupts underneath an overlying

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at La ...

and then melts through to the surface and pools, producing the flat plateau on top with near-vertical walls along the ice-contact margin as the lava cools and hardens. It is a historic landmark, with the remnants of Colonel T. Egenton Hogg's Oregon Pacific Railroad, the Santiam Lodge, and a quarry. The mountain offers

snowshoe Snowshoes are specialized outdoor gear for walking over snow. Their large footprint spreads the user's weight out and allows them to travel largely on top of rather than through snow. Adjustable bindings attach them to appropriate winter footwe ...

and

snowmobile A snowmobile, also known as a Ski-Doo, snowmachine, sled, motor sled, motor sledge, skimobile, or snow scooter, is a motorized vehicle designed for winter travel and recreation on snow. It is designed to be operated on snow and ice and does not ...

trails, and its summit provides views of the surrounding area including volcanoes like the Black Butte stratovolcano,

Mount Washington Mount Washington is the highest peak in the Northeastern United States at and the most topographically prominent mountain east of the Mississippi River. The mountain is notorious for its erratic weather. On the afternoon of April 12, 1934 ...

, Sand Mountain, and Potato Hill.

Geography

Hogg Rock is located in Linn County, in the U. S. state of

. It is close to Santiam Pass, by the Hayrick Butte

, another feature produced from the interaction of volcanic eruptive materials with glaciers. It is close to the

Mount Jefferson Wilderness The Mount Jefferson Wilderness is a wilderness area located on and around Mount Jefferson in the central Cascade Range of Oregon in the United States. The wilderness lies within the Willamette National Forest and Deschutes National Forest. The wi ...

, near where

Oregon Route 22 Oregon Route 22 is an Oregon state highway that runs between the Oregon Coast community of Hebo, to an interchange with U.S. Route 20 near Santiam Pass in the Cascade Mountains. OR 22 traverses several highways of the Oregon state highway ...

and

US Highway 20 U.S. Route 20 or U.S. Highway 20 (US 20) is an east–west United States Numbered Highway that stretches from the Pacific Northwest east to New England. The "0" in its route number indicates that US 20 is a major coast-to-coast route. S ...

intersect with the Cascade Range at Santiam Pass, and sits next to

Oregon Route 126 Oregon OR 126 (OR 126) is a state highway that connects coastal, western, and central parts of the U.S. state of Oregon. A short freeway section of OR 126 in Eugene and Springfield is concurrent with Interstate 105 (I-105). Rout ...

. Hogg Rock lies about north of Collier Cone, a cinder cone at the northern side of the base of the North Sister. The

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

considers Hogg Rock part of the

quadrangle, while Siebert, Simkin, and Kimberly (2010) list it as a volcanic cone of Three Fingered Jack. Hogg Rock lies south of Three Fingered Jack and north of Hoodoo Butte and Hayrick Butte. According to the

Geographic Names Information System The Geographic Names Information System (GNIS) is a database of name and locative information about more than two million physical and cultural features throughout the United States and its territories, Antarctica, and the associated states of ...

, the volcano has an elevation of .

Ecology

The

Oregon Department of Fish and Wildlife The Oregon Department of Fish and Wildlife (ODFW) is a government agency of the U.S. state of Oregon responsible for programs protecting Oregon fish and wildlife resources and their habitats. The agency operates hatcheries, issues hunting an ...

determined in the early 1990s that there was potential for peregrine falcon nests at Hogg Rock, though it was considered low-quality habitat because of its lack of suitable ledges and high amounts of human disturbance.

Wildflower A wildflower (or wild flower) is a flower that grows in the wild, meaning it was not intentionally seeded or planted. The term implies that the plant probably is neither a hybrid nor a selected cultivar that is in any way different from the ...

s and

bracken Bracken (''Pteridium'') is a genus of large, coarse ferns in the family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produce sex cells (eggs ...

ferns occur along roadways. The area has previously been affected by fires.

Geology

North Sister and

mark isolated volcanic centers among the highly

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks incl ...

(rich in magnesium and iron) platform of the central High Cascades. About 4.5 million years ago, eruption of mafic lava filled a subsiding

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58depression, creating the modern mafic edifice of the High Cascades. Compared to the eruptive products at and near North Sister, lava deposits at Mount Washington have a greater abundance of

incompatible element In petrology and geochemistry, an incompatible element is one that is unsuitable in size and/or charge to the cation sites of the minerals of which it is included. It is defined by the partition coefficient between rock-forming minerals and melt b ...

s (elements unsuitable in size and/or charge to the cation sites of the minerals of which it is included.) Hogg Rock shows more similarity to the

basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Amer ...

deposits at North Sister, which are poorly enriched in incompatible elements. The part of the High Cascades that extends south from Mount Jefferson to Santiam Pass includes shield volcanoes, lava domes, and

cinder cones A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions ...

. The high elevation of Matuyama-aged rocks east of Santiam Pass, coupled with exposure of Brunhes-aged rocks to the west, imply the presence of a northward-trending

normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tecton ...

. Part of a mostly mafic chain of volcanoes between the Three Sisters and Mount Jefferson, Hogg Rock has magma with an intermediate composition. A tuya, Hogg Rock is also considered a small lava dome with the flat top typically observed for tuya volcanoes. Unlike most lava domes in the Cascades, which are made of

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite ...

rhyodacite Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of those plutonic rocks that are intermediate in composition between monzogranite and granodiorite. Rhyodacites form from rap ...

, Hogg Rock is comprised by

andesitic Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomin ...

lava. It is thick with steep sides that have glassy margins between in thickness, and the rock forming the dome is heavily jointed. Andesite forming Hogg Rock has an aphyric, only slightly porphyritic texture, with

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more pro ...

, orthopyroxene, and

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...

phenocryst 300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...

s. Along with Hayrick Butte, the

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

content for Hogg Rock measures about 59–60 percent. The volcano has been eroded by glaciers. It was formed during the Pleistocene, with an approximate age of roughly 80,000 years according to Deligne et al. (2017), corresponding to the Wisconsin glacial period; Hill and Priest (1992) assign it an age of 90,000 years ± 20,000 years, while Sherrod et al. argue that its age by

K–Ar dating Potassium–argon dating, abbreviated K–Ar dating, is a radiometric dating method used in geochronology and archaeology. It is based on measurement of the product of the radioactive decay of an isotope of potassium (K) into argon (Ar). Potassium ...

is 80,000 years ± 20,000 years. The volcano exhibits a normal magnetic polarity. Santiam Pass has been assessed for its geothermal energy potential, and there is a drill corehole extending to a depth of south of the highway area. In addition to the expected basaltic andesite lava and a number of

dike Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes ...

s, the core also detected unusual basalt, andesite, and coarse sediment indicative of debris flows. The dating for these samples cannot be confirmed because of the close proximity of Brunhes-aged dikes, which likely heated nearby rock and caused the loss of radiogenic argon.

Human history

Hogg Rock served as a landmark for travelers searching for Hogg Pass, which was later renamed to Santiam Pass by the United States Board on Geographic Names in 1929. This name drew from the

Santiam River The Santiam River is a tributary of the Willamette River, about long, in western Oregon in the United States. Through its two principal tributaries, the North Santiam and the South Santiam rivers, it drains a large area of the Cascade Range a ...

, its name referring to the

Santiam people Santiam people are an indigenous people of the Northwest Plateau, living in Oregon. ...

, who were forced to leave the area and move to the Grand Ronde reservation. Hogg Rock was named after Colonel T. Egenton Hogg, the head of the Oregon Pacific Railroad that was supposed to cross the Cascades in this location. Construction on the railroad began in the 1870s, costing Hogg about $5 million. The railway was intended by Hogg to travel from

Yaquina Bay Yaquina Bay ( ) is a coastal estuarine community found in Newport, Oregon, United States. Yaquina Bay is a semi-enclosed body of water, approximately 8 km² (3.2 mi²) in area, with free connection to the Pacific Ocean, but also diluted ...

to the Snake River. Also known as the Corvallis and Eastern Railroad, it was built by Chinese and Italian workers to connect Newport and

Boise Boise (, , ) is the capital and most populous city of the U.S. state of Idaho and is the county seat of Ada County. On the Boise River in southwestern Idaho, it is east of the Oregon border and north of the Nevada border. The downtown area' ...

, though in actuality it only extended to Idanha. Hogg ran out of money, but trying to meet the government contract stipulation that he finished crossing the Cascade Range before claiming land grants, he built of isolated railtracks around Hogg Rock before getting a 14-person crew to pull a boxcar on them. He then claimed the isolated tracks around the tuya were a train railway. Hogg eventually declared bankruptcy in 1890. After other businesspeople tried to pick up the railroad, it was absorbed by the Southern Pacific Transportation Company. Today, remnants of the railroad are still present at the volcano. Santiam Pass, located at an elevation of , marks a historic feature in the Cascade Range. West of Mount Washington and Three Fingered Jack, there are three major routes. One travels north and west down the

North Santiam River The North Santiam River is a tributary of the Santiam River in western Oregon in the United States. It drains of the Cascade Range on the eastern side of the Willamette Valley east of Salem. It rises in the high Cascades in eastern Linn count ...

, the same path followed by Hogg's railroad, while another moves southwest along the McKenzie River. The third route moves west over Tombstone Pass, reaching the

South Santiam River The South Santiam River is a tributary of the Santiam River, about long, in western Oregon in the United States. It drains an area of the Cascade Range into the Willamette Valley east of Corvallis. It rises in the Cascades in southeastern Linn ...

, and was followed by the Santiam Wagon Road from 1865 to 1914 as well as the auto race of the 1905

Lewis and Clark Centennial Exposition The Lewis and Clark Centennial Exposition, commonly also known as the Lewis and Clark Exposition, and officially known as the Lewis and Clark Centennial and American Pacific Exposition and Oriental Fair, was a worldwide exposition held in Portlan ...

. In addition to the railroad, there is also a quarry at Hogg Rock and the Santiam Pass Ski Lodge building. Santiam Pass Ski Lodge, constructed by the

Civilian Conservation Corps The Civilian Conservation Corps (CCC) was a voluntary government work relief program that ran from 1933 to 1942 in the United States for unemployed, unmarried men ages 18–25 and eventually expanded to ages 17–28. The CCC was a major part of ...

in 1939–1940, and operated for 46 years as a ski lodge with overnight dorms and later as a youth camp. In 1986 it was boarded up. It has survived major forest fires in 1968 and 2003, withstanding flames in the latter fire after firefighters swathed it in

kevlar Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s a ...

sheets. In early 2018, Willamette National Forest issued a Special Use Permit to Dwight and Susan Sheets, Friends of Santiam Pass Ski Lodge to restore the lodge and operate it year-round as a day lodge and rental venue. Funds for restoration project are from private grants and donations. The estimated timeline for the completion of the restoration is 4-5 years.

Recreation

The Hoodoo ski area is located on nearby Hoodoo Butte. Hogg Rock can be reached from a

trail that starts at the Santiam Pass Sno-Park, which has restrooms and a snow play area for children. Entrance to the Sno-Park requires a permit. There is also a

trail that moves west from Santiam Lodge and then north at Hogg Rock, traveling along the remnants of Hogg's railroad. It eventually reaches the Hogg Rock summit by passing a trail left of a rock quarry at the mountain. The peak offers views of the Black Butte stratovolcano, Mount Washington, Hoodoo Butte, Sand Mountain, Three Fingered Jack, and Potato Hill. There is a viewpoint on the western slope of Hogg Rock shows forests on Potato Hill and Hoodoo Butte as well as the Hoodoo Ski Area.

Notes

* Dole (1968) claims that Hogg Rock and Hayrick Butte have glassy margins with thicknesses up to .

References

Sources

* * . * . * . * . * * . * . * * * . * * * . * * . * . * {{Volcanoes of Oregon , state=collapsed Cascade Range Cascade Volcanoes Mountains of Linn County, Oregon Mountains of Oregon Pleistocene volcanoes Subduction volcanoes Tuyas of the United States Volcanoes of Linn County, Oregon Volcanoes of Oregon Willamette National Forest Volcanoes of the United States Lava domes