Big Sky in Gallatin County, Montana — The American West (Mountains)

Lone Mountain

Photographed by Barry Swackhamer, July 26, 2021

1. Lone Mountain Marker

Captions: (center) Aerial view of Madison and Gallatin ranges and the Spanish Peaks.; (bottom center) Lone Mountain, insert Bill Browning pack trip, 320 Ranch, Madison Range.: (bottom right) Drawing by Roger Swanson of UDGS. The fold next to Lone Mountain is Andecite Mountain looking north.

Inscription. Geologic processes have created a winter wonderland for skiers and snow boarders on Lone Mountain, the prominent peak that rises above Big Sky. Some geologists think that if the mountain was cut in half, there would be a Christmas tree pattern of igneous rock within the layers of sandstone and shale. Magma from deep in the earth rose up along a vertical crack, then spread out laterally between the layers of sedimentary rock. The magma never erupted as a volcano, but crystalized into an igneous rock called dacite before reaching the surface of the earth. The"trunk and branches of the tree" are dacite. The igneous rock and adjacent baked sedimentary rocks are much more resistant to erosion than softer sedimentary rock, which has eroded away to leave the mountain standing tall. Glaciers, landslides, and rock fall have greatly modified Lone Mountain. The cirques contain rock glaciers, which are piles of rock with year-round ice in their cores. Like ice glaciers, they slowly creep down the mountain slopes.
The rugged mountains to the northwest of Big Sky are the Spanish Peaks, composed of metamorphic rock that is billions

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of years older than the igneous and sedimentary rocks of Lone Mountain. These extremely old rocks were brought up from the depths along an enormous fault zone that extends from the Tobacco Root Mountains to the town of Gardiner north of Yellowstone Park.
The mountains provided a spectacular backdrop for visitors to one of the Gallatin Canyon's many dude ranches. The ranches offer visitors adventure and a taste of the Old West. They rode horses, hiked mountain trails, fished the areas's trout streams, and reveled in the solitude of the mountains. The ranches were immensely popular before World War II, but their popularity diminished in the 1950s until now only a few remain.

GeoFacts:
• This area contains the northern most remnants of the 1.7 million-year-old Huckleberry Ridge Tuff, which was deposited by extremely hot flows of volcanic ash that swept across the region. The ash was the product of immense eruptions fro the Yellowstone Caldera, about 50 miles to the south.
• A volcanic field covered an area of about 9,000 square miles of southern Montana and northern Wyoming about 50 million years ago, including much of the

Photographed by Barry Swackhamer, July 26, 2021

2. Lone Mountain Marker

Soldiers Chapel in the background.

Gallatin Range. Many large, violent eruptions occurred that deposited volcanic rocks over a vast area.
• A cirque is a bowl-like valley or hollow carved by a glacier.

Geo-Activity:
• Remember that Lone Mountain is a volcano that never erupted. Why? Because magma that rose up through the mountain spread out among the rock instead of erupting out the top of Lone Mountain. Draw a picture of a volcano erupting then draw a picture of that happened to the magma inside Lone Mountain.

Erected by Montan Department of Transportation.

Topics. This historical marker is listed in this topic list: Natural Features.

Location. 45° 15.82′ N, 111° 15.229′ W. Marker is in Big Sky, Montana, in Gallatin County. It is on Gallatin Road near Lone Mountain Trail (State Highway 64), on the right when traveling north. Touch for map. Marker is at or near this postal address: 47905 Gallatin Road, Big Sky MT 59716, United States of America. Touch for directions.

Regionally, this marker is in Yellowstone Country

and in Greater Bozeman.

It is also in the American Mountain West

and in the Lewis

Lone Mountain image. Click for full size.

Photographed by Freeimages.com, June 30, 2005

3. Lone Mountain

& Clark Corridor.

Globally, it is in North America,

the Rocky Mountains,

the Western Hemisphere,

the Western World,

and the Anglosphere.

Historically, it finds itself in what was once Rupert’s Land

and also the Louisiana Purchase.

Other nearby markers. At least 8 other markers are within 4 miles of this marker, measured as the crow flies: Crail Ranch (approx. 1.9 miles away); The Historic Crail Ranch - East View (approx. 2.1 miles away); The Historic Crail Ranch - South View (approx. 2.1 miles away); The Historic Crail Ranch - North View (approx. 2.1 miles away); The Historic Crail Ranch - West View (approx. 2.1 miles away); Crail Ranch Buildings (approx. 2.1 miles away); Welcome to the Historic Crail Ranch (approx. 2.1 miles away); B-K (B Bar K) Ranch (approx. 3.6 miles away). Touch for a list and map of all markers in Big Sky.

Credits. This page was last revised on February 26, 2022. It was originally submitted on February 26, 2022, by Barry Swackhamer of Brentwood, California. This page has been viewed 616 times since then and 70 times this year. Photos: 1, 2, 3. submitted on February 26, 2022, by Barry Swackhamer of Brentwood, California.