DESCRIPTION:
Mount Bachelor Volcanic Chain, Oregon

Bachelor05_mount_bachelor_from_south_sister_02-09-05.jpg
Mount Bachelor as seen from South Sister.
USGS Photograph taken in February 9, 2005, by Gene Iwatsubo.
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Mount Bachelor

Location: Oregon

Latitude: 43.979 N

Longitude: 121.688 W

Height: 2,763 Meters (9,065 Feet)

Type: Stratovolcano

The Three Sisters area contains 5 large cones of Quaternary age-- North Sister, Middle Sister, South Sister, Broken Top, and Mount Bachelor. ...

Several large basaltic shield volcanoes along the (Cascade) range have steep-sided summit cones, such as ... Mount Bachelor ... ...

Mount Bachelor, which is between 11,000 and 15,000 years old is the youngest of these volcanoes in the Cascades.

The Mount Bachelor volcanic chain provides one example of the type and scale of eruptive activity that has produced most of the High Cascades platform, which consists chiefly of scoria cones and lava flows, shield volcanoes, and a few steep-sided cones of basalt and basaltic andesite. The chain is 25 kilometers long; its lava flows cover 250 square kilometers and constitute a total volume of 30-50 cubic kilometers.

The Mount Bachelor volcanic chain is located in the Deschutes National Forest, 20 kilometers WSW of Bend in central Oregon. The north flank of Mount Bachelor is readily accessible during all season from the Cascade Lakes Highway. ... Mount Bachelor Ski Area operates chairlifts to the summit during the summer as well as the ski season (weather permitting).

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Aerial view, Mount Bachelor and Sparks Lake.
USGS Photograph taken in 1985 by Lyn Topinka.
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The Mount Bachelor volcanic chain is located in the eastern part of the central High Cascades of Oregon, south-southeast of the clustered composite volcanoes of the Three Sisters and Broken Top. The 25-kilometer-long chain is composed of numerous scoria cones with related lava flows and three broad shield volcanoes, the northernmost of which is capped by the steep-sided summit cone of Mount Bachelor (formerly called Bachelor Butte).

... The eve of World War II. A war that saw 90,000 soldiers training at Camp Abbot, now Sunriver. A major economic boom for Bend, then a town of 10,000. Bend's sawmills were the mainstay of the community's economy through the war years, with agriculture a strong second. Cork boots and cowboy boots were the featured footwear. A few snow loving zealots did manage to open a small ski hill in 1941 which they dubbed Bachelor Butte. It was a gesture of cheer during a trying time for the community and the nation. Little did this group realize they had just implemented Bend's new economic plan. And it was a good thing they did. ...

For the unexpected closure of the Shevlin-Hixon mill in 1950 put hundreds out of work It was the first of many reminders over the next few decades that it is unwise to put all of Bend's economic eggs in one basket. Brooks Scanlon bought the ailing mill and, thanks to a dramatic resurgence of the timber industry, eight years later completed a 3 million dollar expansion. Meanwhile, Bachelor Butte continued to grow, graduating from a local ski hill to a full fledged ski resort in 1958. ...

But in the 1980's, the unanticipated happened. Due to a national downturn in homebuilding and lumber prices, the timber industry, and Bend along with it, took a nosedive. Storefronts stood empty along Wall and Bond streets. The jobless rate in the county hit an all time high of 15%. And yet, now typical of Bend, sprouts of economic optimism pushed through the bleak statistics in the form of the construction of the Mountain View Mall, the completion of the Summit Chair to the top of Mount Bachelor, and the opening of the High Desert Museum, a national caliber institution built with donations from those who had faith that the area would return to economic robustness.

In 1957 Mount Bachelor (formerly known as Bachelor Butte) was opened as a ski and recreation area. Bend started to become and grow into visitor destination for summer and winter seasons. Populations from the rainy Western portion of the state come over to escape the rain to Bend to experience the sunshine and variety of outdoor activities.

1958: Pomalift starts operation at Bachelor Butte.

By 1950 Shevlin-Hixon had sawed its last log, and Deschutes County's population had reached almost 22,000. The 1960s saw further growth in the region with plans being made to convert Camp Abbot into Sunriver. Bachelor Butte Ski Lodge opened for business and Central Oregon Community College broke ground for its campus on Awbrey Butte after outgrowing its initial site on Wall Street.

The Mount Bachelor volcanic chain is located in the eastern part of the central High Cascades of Oregon, south-southeast of the clustered composite volcanoes of the Three Sisters and Broken Top. The 25-kilometer-long chain is composed of numerous scoria cones with related lava flows and three broad shield volcanoes, the northernmost of which is capped by the steep-sided summit cone of Mount Bachelor (formerly called Bachelor Butte). Together these features cover approximately 250 square kilometers and constitute a total magma volume of 30-50 cubic kilometers. Individual volcanoes within the chain are typical of the thousands of monogenetic volcanoes that form the High Cascade landscape between major composite volcanoes.

Eruptions of the Mount Bachelor volcanic chain were dominantly effusive, but also included minor explosive activity that built cones of agglutinate spatter, bombs, and scoria. The eruptions can be divided into four episodes. The oldest episode occurred approximately 18,000 - 15,000 years ago during glacier retreat. Eruptions at vents just west of Sparks Lake in the northwest part of the chain interacted with glacier ice and meltwater to form hyaloclastite; a thick sequence of lava flows that was impounded on three sides by glacier ice and now forms a steep-sided plateau. However, most activity during the oldest episode was focused in the central part of the chain and built the shield volcano capped by Sheridan Mountain.

During the second episode, eruptive activity shifted southward to a chain of scoria cones and lava flows that extends from near Sheridan Mountain to the south end of the chain. Eruptions during the third episode of activity built the shield volcano of Kwohl Butte, the shield that underlies Mount Bachelor, and last, the summit cone of Mount Bachelor. By approximately 12,000 years ago, the age of the oldest glacial moraines recognized on Mount Bachelor, the cone had nearly attained its present size. The moraines are overlain by the youngest lava flows of the third episode, which were erupted from vents on the north flank.

The final eruptive episode of the chain 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 ceased before 6,845 years BP, as tephra of that age from the climactic eruption of Mount Mazama is found on all products of the Bachelor chain. ...

The summit of Mount Bachelor consists of a northwest-trending cluster of small pyroclastic cones, shallow collapse craters, low blocky domes, and, in the cirque on the north side, several lava plugs. The steep (25 degrees) upper flanks are covered with lava flows that display well preserved levees and flow fronts; many emerge from lava tubes. Several small parasitic shields on the south and north flanks impart a north-south elongation to the cone. ...

No evidence of thermal activity exists on the volcano. Deep wells that form in the snowpack have been described as fumaroles; however, these features are formed by air moving in and out of the porous edifice with changes in the atmospheric pressure.

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