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.

A prominent landmark for the Rogue River Valley, the mountain is north of Mount Shasta, and south-southwest of Crater Lake.

Designated by the United States Congress in 1984, it stretches from Crater Lake National Park to Oregon Route 140 at the south and ranges in elevation from 3,800 feet (1,200 m) in the Middle Fork canyon of the Rogue River to the peak of McLoughlin.

[11] The wilderness area encompasses more than 200 bodies of water including ponds and lakes, in addition to forests and mountain ridges.

[11] The local area has warm, dry summers during the daytime with cool nights,[12] and snowy winters that impede access to the Sky Lakes Wilderness through July.

[11] Moisture is limited between June and October barring occasional thunderstorms, which accounts for a very short growing season between ice thawing and drought.

[21] James Smith from the United States Geological Survey expanded on Maynard's findings, producing a map of the McLoughlin region.

[22] Formed towards the end of the Pleistocene Epoch, these mountains are underlain by more ancient volcanoes that subsided due to parallel north–south faulting in the surrounding region.

[24] Within Oregon, plutons, or bodies of intrusive igneous rock that crystallize from magma cooling below the surface of the Earth, lay between 47 and 68 miles (75 and 110 km) northwest of the major High Cascade axis.

Pleistocene glaciers carved out McLoughlin's major volcanic cone, excavating two solidified lava tubes that reached the summit crater.

It produced basaltic andesite lava flows that have not been heavily eroded, but during Pleistocene glacial advance, ice streams on the volcano ate away at the cinder cone that formed Brown Mountain's summit.

Like Brown Mountain, Pelican Butte has a cinder cone on the top of its summit, in addition to a glacial cirque and ravine that were excavated on its northeastern side.

The northwestern flank has volcanic vents that produced lava flows responsible for inundating the Fourbit Creek valley 4 miles (6.4 km) from the base of McLoughlin, which extend up to the Big Butte Springs.

Other lava flows from earlier eruptions reach at least 6 miles (9.7 km) from the base of the mountain, a number of which run along the Oregon Route 140 highway.

The entire third stage is thought to have happened after the last Pleistocene glaciers in the area had melted, due to a general lack of weathering and fresh appearance of the solidified lava.

The freshest lava flows at Mount McLoughlin occur on the southern and western flanks of the mountain, and they are thought to be between 30,000 and 20,000 years old.

[29] Mount McLoughlin's main volcanic cone has not erupted during the Holocene,[33] with the last production of lava flows taking place between 30,000 and 20,000 years ago.

[33] The closest seismic monitoring stations lie 62 miles (100 km) to the south near Mount Shasta and the Medicine Lake Volcano.

[36] The Little Butte Creek which drains from McLoughlin was called "So-ytanak", translating as "corner" or "rock house", by the Upper Takelma people.

[2] Settlers living near the surrounding Sky Lakes Wilderness trapped beavers and martens during the winter seasons, hunted, and grazed sheep in warmer months.

[11] Mount McLoughlin's first known ascent took place in 1858, when Joseph Burpee, William Wilkinson, Dr. Greer, Henry Klippel, John S. Love, and Robert Haines, from the city of Jacksonville, reached the summit from the northeast.

[4] As of 1926, Mount McLoughlin's western flank acts as the municipal watershed for Medford, its melted snow feeding the Big Butte Springs near the city.

[12] The trail receives moderate to heavy use each year; the peak is easiest to reach from July through September, when the trailhead is accessible by vehicle and snow is minimal along the path.

[42] The access road from Oregon Route 140 may also be closed due to snow, requiring a longer approach on snowshoes or cross country skis.