DESCRIPTION:
Mount McLoughlin Volcano, Oregon

McLoughlin05_aerial_mount_mcloughlin_from_west_12-08-05.jpg
Aerial view, Mount McLoughlin, Oregon, as seen from the west.
USGS Photograph taken on December 8, 2005, by Mike Doukas.
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Mount McLoughlin (Mount Pit or Pitt) rises 1,200 meters as a steep-sided, dominantly basaltic andesite lava cone above the low Pliocene and Pleistocene basaltic andesite shields on which it is built. McLoughlin is easily recognized from as far away as Medicine Lake in California, along I-5 between Yreka, California, and Medford, Oregon, or around the rim of Crater Lake. Although it is the tallest volcano between Shasta and Crater Lake, McLoughlin, with a volume of only 13 cubic kilometers, is dwarfed by the bulk of Shasta (350 cubic kilometers) and Mazama (130 cubic kilometers [Crater Lake]).

When viewed from the south or southeast it appears a a seemingly perfectly symmetrical Fuji-like volcano. However, when seen from the east, along the shores of Klamath Lake, or from the north along Crater Lake's rim, it is apparent that a major part of the mountain is missing. Late Pleistocene glaciers have carved away the entire northeast side of the mountain, lowering the summit about a hundred meters, excavated the large bowl-like cirque, and exposed the congealed lava that fills two small central conduits. Steeply dipping layers of pyroclastic breccia and tuff and numerous interlayered lava flows are exposed in the walls of the cirque. An explosive origin is sometimes ascribed to this cirque; however, there is no evidence of deposits that would have resulted from such an explosion. Glacial striae and other glacial features are common in the cirque, and glacial deposits such as moraines and till are present at the mouth of the cirque and around the north base of the mountain. Finally, the composition of McLoughlin's lava is much more mafic than that of other volcanoes at which explosive events of the required size have occurred. ...

Access to Mount McLoughlin and its close neighbors, Brown Mountain and Pelican Butte, is remarkably easy via Oregon Highway 140 between Medford and Klamath Falls. The thick conifer forests around the bases of these mountains with their many campgrounds are well known to southern Oregon residents but often overlooked by others in a hurry to get to better known Crater Lake, 55 kilometers to the north. Recreational activities include hiking and fishing in the summer and snow sports in the winter. Parts of Mount McLoughlin and Pelican Butte are in the Sky Lakes Roadless Area. Mount McLoughlin can be climbed during mid to late summer after snow has melted from the trail.

John McLoughlin was one of the most influential figures of the fur trade and settlement periods of Pacific Northwest history. Chief Factor of the Columbia District of the British Hudson's Bay Company, he reigned as a benevolent autocrat, befriended Americans, and eventually became an American citizen at Oregon City. ...

John McLoughlin has been honored in many ways for the role he played in Oregon's early history. In 1905 the Oregon Legislative Assembly renamed the 9,495 foot Mount Pitt in southern Oregon to Mount McLoughlin. The United States Board of Geographic Names recognized that change in 1912.

According to legend, about 1821, a Spanish explorer reported that while climbing Mount Diablo near San Francisco he saw Mount Shasta. He called it "Jesus and Maria" because of the double peaks. About this time the Russians probably viewed Mount Shasta from the coast near Fort Ross. Hudson Bay Company trapper, Peter Skene Ogden left Fort Vancouver and journeyed through central Oregon, trapping beaver. The trappers wanted fur from beaver, otter, and martins to export to England. They succeeded over the course of several years to dramatically reduce the population of these small fur-bearing animals. To this day it is rare to see these animals. Ogden noted in his journal on February 14, 1827: "I have named this river Sastise River. There is a mountain equal in height to Mount Hood or Vancouver; I have named Mt. Sastise. I have given these names, from the tribes of the Indians." However historians believe he saw the Rogue River and Mount McLoughlin. Early maps portrayed today's Mount Shasta variously as Mount Pitt, Mount Jackson, and Mount Simpson and said that it was over 20,000 feet above sea level. For the most part, the explorers and fur trappers traveled through the area but did not stay for any length of time.

Mount Shasta Volcano Information

Mount McLoughlin is a young volcano. A pronounced magnetic high centered just east of McLoughlin's main vent is interpreted as indicating that most of the main cone is normally polarized and thus less than approximately 700,000 years old. The well preserved shape of the mountain's west and south flanks, the lack of soil development on many flows, and preservation of primary flow features suggests that the bulk of the main cone is no older than 200,000 years, with much of it probably younger. The main cone was essentially complete before the last major Pleistocene glaciation. Many flank flows are younger than the main cone; some may be as young as 20,000 - 30,000 years.

Early thick flows of light-colored pyroxene-bearing lava extend east beyond the mountain's base for at least 10 kilometers. They crop out along Highway 140 and are well exposed in the upper one-third of the steep grade on Highway 140 approximately 3 kilometers east of the junction with the road to Lake of the Woods. Extensive black clinkery flank flows of olivine=bearing basaltic andesite and andesite poured from the northwest side of the volcano, filled the old valley of Fourbit Creek for approximately 6 kilometers beyond the mountain's base, and stopped at the site of the present-day Big Butte Springs. These large-volume springs, whose catchment area is the whole northwest slope of Mount McLoughlin, gush from the end of the flows and are the domestic water source for Medford and other towns in the Bear Creek Valley.

Another clinkery black basalt andesite flank flow emerges from the volcano above the 1,500-meter level, fills a stream valley for approximately 11 kilometers, and descends to an elevation of 900 meters. Despite its great length and blocky character this remarkable flow is less than 160 meters wide for more than 4 kilometers of its length.

Detailed study of the main edifice in the early 1970's divided the eruptive history into 3 stages. Chemical analyses indicate that the composition of rocks ranges from approximately 53 to approximately 57 percent SiO2. Thus, although Mount McLoughlin is commonly called an andesitic volcano, as inferred from its steep-sided form, it is composed mostly of basaltic andesite.

Located within the Sky Lakes Wilderness the 5.5 mile long trail to the summit of Mount McLoughlin winds through rocky terrain. After it leaves the Pacific Crest Trail (at a point a little over a mile from the parking lot), the trail ascends through a boulder strewn forest. Watch for blazed trees and a well worn path. Above timberline, marks spray-painted on boulders are unreliable. Once you reach the main ridge, follow the ridge line up to the summit. Watch your footing and avoid the loose scree on the left. Each year a number of people become disoriented or lost on the way back down, usually due to coming down a different route than they used when climbing the mountain. Tempting as it may seem to descent the sandy, cinder slope, the lower you get down this slope, the further away you become from the trail -- and once down to the timberline, it's a 2-mile strenuous boulder-hopping hike back east to the trail. The proper way to descend is simply to follow the same ridge-line route that took you to the summit.

Elevation: 5,600 feet to 9,495 feet
Length: 11 miles round trip
Type: Hiker only
Recommended Season: Summer
Use Level: Moderate to Heavy
Difficulty Level: Difficult

Mount McLoughlin can be climbed during mid to late summer after snow has melted from the trail. To reach the trail head, turn north from Highway 140, east of the Cascade Crest, onto the Four Mile Lake road and proceed approximately 4 kilometers. A sign marks the trail's start. Carry water as no streams cross the trail. The 10-kilometer-long, moderately steep trail is marked above tree line by red circles painted on rocks. Take care, as these inconspicuous trail markers are easily missed, especially during descent.

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