Mount Bachelor
Encyclopedia
Mount Bachelor, formerly named Bachelor Butte, is a stratovolcano
atop a shield volcano
in the Cascade Volcanic Arc
and the Cascade Range
of central Oregon
.
The Mount Bachelor ski area has operated on the mountain since 1958.
The volcano lies at the northern end of the 15 miles (24.1 km) long Mount Bachelor Volcanic Chain.
area of Oregon. Bachelor is composed mainly of basalt
and basaltic andesite
.
It last erupted between 8,000 and 10,000 years ago and is entirely covered with Mazama Ash
from the catastrophic eruption of Mount Mazama
about 6,845 years ago. There is no geothermal activity at present, though some areas popularly thought to be fumarole
s are caused by air movement through the porous structure. Several are near the top of the Pine Marten chairlift and occasionally present a hazard to skiers and snowboarders where the snow is undermined.
s, lava flows and three shield volcanoes.
The northernmost shield is capped by a steep-sided summit cone of Mount Bachelor. Minor explosive activity built the many cinder cones which fed the many lava flows that account for the bulk of the erupted material.
Eruptive activity of the chain can be considered in four episodes:
operates a chairlift during the summer as well as during the ski season (weather permitting). The resort is one of the largest in the Pacific Northwest
with a skiable area of 3683 acres (14.9 km²) and a vertical drop of 3365 feet (1,025.7 m).
, a group of three volcanic mountains that are northwest of Mount Bachelor. In early days Bachelor Butte was frequently called "Brother Jonathan", or "Mount Brother", but like the names of the Three Sisters
, "Johnathan" and "Brother" fell out of use.
The resort developers were concerned that skiing on a butte might be perceived by consumers as "small-time" and so named their resort Mount Bachelor. Over time the popularity of the ski area led to the name Mount Bachelor coming into popular usage and in a divided decision, the Oregon Geographic Names Board
voted to change the name from Bachelor Butte to Mount Bachelor.
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
atop a shield volcano
Shield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...
in the Cascade Volcanic Arc
Cascade Volcanoes
The Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 mi ...
and the Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...
of central Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
.
The Mount Bachelor ski area has operated on the mountain since 1958.
The volcano lies at the northern end of the 15 miles (24.1 km) long Mount Bachelor Volcanic Chain.
Geology
Mount Bachelor was formed between 11,000 and 15,000 years ago as a shield volcano but was later capped with a stratovolcano as the eruptions apparently became more explosive over time. It is the youngest prominent volcano in the Three SistersThree Sisters (Oregon)
The Three Sisters are three volcanic peaks of the Cascade Volcanic Arc and the Cascade Range in Oregon, each of which exceeds in elevation. They are the third, fourth, and fifth highest peaks in the state of Oregon and are located in the Three Sisters Wilderness, about southwest from the nearest...
area of Oregon. Bachelor is composed mainly of basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
and basaltic andesite
Basaltic andesite
Basaltic andesite is a black volcanic rock containing about 55% silica. Minerals in basaltic andesite include olivine, augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central America and the Andes of South America. Basaltic andesite is common in...
.
It last erupted between 8,000 and 10,000 years ago and is entirely covered with Mazama Ash
Mazama Ash
The Mazama Ash is a large geologically recent volcanic ash deposit that covers portions of the U.S. states of California, Oregon, Washington, Idaho, Montana, Nevada, Wyoming and Utah, as well as the Canadian provinces of British Columbia, Alberta and southwestern Saskatchewan...
from the catastrophic eruption of Mount Mazama
Mount Mazama
Mount Mazama is a destroyed stratovolcano in the Oregon part of the Cascade Volcanic Arc and the Cascade Range. The volcano's collapsed caldera holds Crater Lake, and the entire mountain is located within Crater Lake National Park....
about 6,845 years ago. There is no geothermal activity at present, though some areas popularly thought to be fumarole
Fumarole
A fumarole is an opening in a planet's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide. The steam is created when superheated water turns to steam as its pressure drops when it emerges from...
s are caused by air movement through the porous structure. Several are near the top of the Pine Marten chairlift and occasionally present a hazard to skiers and snowboarders where the snow is undermined.
Mount Bachelor Volcanic Chain
The Mount Bachelor volcanic chain, southeast of South Sister, consists of Mount Bachelor itself and a series of cinder coneCinder cone
According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...
s, lava flows and three shield volcanoes.
The northernmost shield is capped by a steep-sided summit cone of Mount Bachelor. Minor explosive activity built the many cinder cones which fed the many lava flows that account for the bulk of the erupted material.
Eruptive activity of the chain can be considered in four episodes:
- The oldest episode occurred approximately 18,000 - 15,000 years ago during glacial retreat. Most activity during this episode was located in the central part of the chain and built a shield volcano called Sheridan Mountain. In an area near Sparks Lake a group of vents formed beneath glacial ice and interacted with the ice to form hyaloclastiteHyaloclastiteHyaloclastite is a hydrated tuff-like breccia rich in black volcanic glass, formed during volcanic eruptions under water, under ice or where subaerial flows reach the sea or other bodies of water. It has the appearance of angular flat fragments sized between a millimeter to few centimeters...
deposits and thick lava flows impounded by glacial ice. The resulting steep sided plateau is capped by Talapus and Katsuk Buttes. - During the second episode, eruptive activity was along the chain of scoria cones and lava flows that extends from the south side of Sheridan Mountain to the explosion crater at the south end of the chain.
- During the third episode of eruptive activity built the shield volcano of which is capped by Kwohl Butte and the shield that underlies Mount Bachelor. The final phase of this episode built the summit cone of Mount Bachelor. The oldest glacial moraines recognized on Mount Bachelor are approximately 12,000 years old so the cone had nearly attained its present size by then. These moraines are overlain by the youngest lava flows of the third episode.
- The last eruptive episode occurred approximately 8,000 to 10,000 years ago and produced a scoria cone and lava flows on the lower north flank of Mount Bachelor. All activity ended before 6,845 C-14 years BP, since tephraTephra200px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at center of the photo is [[rhyolitic]] tephra from [[Hekla]]....
from the climactic eruption of Mount Mazama is found on all deposits of the Bachelor chain.
Skiing
Mount Bachelor ski areaSki resort
A ski resort is a resort developed for skiing and other winter sports. In Europe a ski resort is a town or village in a ski area - a mountainous area, where there are ski trails and supporting services such as hotels and other accommodation, restaurants, equipment rental and a ski lift system...
operates a chairlift during the summer as well as during the ski season (weather permitting). The resort is one of the largest in the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
with a skiable area of 3683 acres (14.9 km²) and a vertical drop of 3365 feet (1,025.7 m).
Name
Mount Bachelor is so called because it "stands apart" from the Three SistersThree Sisters (Oregon)
The Three Sisters are three volcanic peaks of the Cascade Volcanic Arc and the Cascade Range in Oregon, each of which exceeds in elevation. They are the third, fourth, and fifth highest peaks in the state of Oregon and are located in the Three Sisters Wilderness, about southwest from the nearest...
, a group of three volcanic mountains that are northwest of Mount Bachelor. In early days Bachelor Butte was frequently called "Brother Jonathan", or "Mount Brother", but like the names of the Three Sisters
Three Sisters (Oregon)
The Three Sisters are three volcanic peaks of the Cascade Volcanic Arc and the Cascade Range in Oregon, each of which exceeds in elevation. They are the third, fourth, and fifth highest peaks in the state of Oregon and are located in the Three Sisters Wilderness, about southwest from the nearest...
, "Johnathan" and "Brother" fell out of use.
The resort developers were concerned that skiing on a butte might be perceived by consumers as "small-time" and so named their resort Mount Bachelor. Over time the popularity of the ski area led to the name Mount Bachelor coming into popular usage and in a divided decision, the Oregon Geographic Names Board
Oregon Geographic Names Board
The Oregon Geographic Names Board is responsible for recommending names for geographic features in the state of Oregon. The board submits its recommendations to the United States Board on Geographic Names for approval...
voted to change the name from Bachelor Butte to Mount Bachelor.
See also
- Cascade VolcanoesCascade VolcanoesThe Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 mi ...
- Geology of the Pacific NorthwestGeology of the Pacific NorthwestThe geology of the Pacific Northwest refers to the study of the composition , structure, physical properties and the processes that shape the Pacific Northwest region of the United States and Canada...
- Deschutes National ForestDeschutes National ForestThe Deschutes National Forest is a United States National Forest located in parts of Deschutes, Klamath, Lake, and Jefferson counties in central Oregon. It comprises 1.8 million acres along the east side of the Cascade mountains. In 1908, the Deschutes National Forest was established from parts...