Dupuyer in Pondera County, Montana — The American West (Mountains)

The Front Range of the Rockies

Photographed by Barry Swackhamer, August 12, 2022

1. The Front Range of the Rockies Marker

Inscription. The geological history of the front range of the Rocky Mountains is just as jumbled and complicated as the mountains appear from this vantage point. Geological forces far to the west caused this remarkable backdrop. About seventy million years ago, the subduction of the Farallon tectonic plate under the North American plate gave rise to the Rockies. Over millions of years, the crust pushed upward and then slid the older rock west over the top of the younger rock. Called an overthrust fault, it pushed up, deformed, and folded the rocks as it moved. Pleistocene ice sheets later carved the rocks into the scrambled geological appearance we see today.
The gray rocks are Madison Limestone, About 350 million years ago. much of Montana was submerged under a shallow sea. Billions of tiny marine creatures thrived in the water and when they died their bodies settled into the muck on the sea bed. After hundreds of millions of years of accumulation and many more millions of years it metamorphosed int the pale gray rocks of the front range. Because Madison Limestone resists weathering and erosion much better than most other kinds

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of rocks, it created the spectacular cliffs and dramatic ridges you see west of here.
The front range range has been a paradise for wildlife for at least seventy million years. Duck-billed hadrosaurs and triceratops once roamed the shores of an ancient sea. Now it is the home of many different species, including grizzlies, elk, mountain lions, deer, wolves, moose, and rattlesnakes.

Erected by Montana Department of Transportation.

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

Location. 48° 11.908′ N, 112° 30.414′ W. Marker is in Dupuyer, Montana, in Pondera County. It can be reached from the intersection of U.S. 89 and Swift Dam Road, on the left when traveling north. The marker is at the Dupuyer Rest Area, just north of town. Touch for map. Marker is in this post office area: Dupuyer MT 59432, United States of America. Touch for directions.

Regionally, this marker is in Western Montana

and in Russell Country. It is also in the American Mountain West

and in the Lewis & Clark Corridor.

Globally, it is in North America,

the Rocky Mountains,

Photographed by Barry Swackhamer, August 12, 2022

2. The Front Range of the Rockies Marker

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 3 other markers are within 9 miles of this marker, measured as the crow flies: Dupuyer (here, next to this marker); The 546th Missile Squadron (approx. 8.7 miles away); Captain Meriwether Lewis (approx. 8.7 miles away).

Additional keywords. geology

A little roadside entertainment. image. Click for full size.

Photographed by Barry Swackhamer, August 12, 2022

3. A little roadside entertainment.

Front Range of the Rockies in the background

Credits. This page was last revised on April 10, 2023. It was originally submitted on April 10, 2023, by Barry Swackhamer of Brentwood, California. This page has been viewed 291 times since then and 29 times this year. Photos: 1, 2, 3. submitted on April 10, 2023, by Barry Swackhamer of Brentwood, California.