Roc Doc Travel

 Mountain Pass, California Sevier-Laramide Project See the southernmost exposures of the Cretaceous Sevier orogeny! Mountain Pass in southeastern California is the site of America's most important rare earth element (REE) mine.  The mine lies in the footwall just below the early to mid-Cretaceous Keystone thrust, part of the Sevier orogeny and one of North America's largest thrust faults.   Mountain Pass is on Interstate 15 between Los Angeles and Las Vegas.  Las Vegas is shown at the upper right; the closed solar plant at Ivanpah is the three dark blotches in the valley NE of the pass.  Millions have seen this location as they drive by, but few have know the site's significance. Looking north from west of the mine, the Keystone thrust (red) places Cambrian strata over the Proterozolic granitic rocks, including the unusual rock called carbonatite that hosts the REEs. The carbonatite intruded into this leucogranite, which contains almost no dark minerals....

  Sevier-Laramide Project Introduction The Sevier-Laramide Project is a publicly-accessible archive of photos, videos, maps, and papers that document exposures of Sevier and Laramide faults and folds from southern California to northern Montana.  They were acquired by Dr. Robert W. Clayton, professor of Geology at Brigham Young University - Idaho during a 2025 Sabbatical.  All materials here and on YouTube are copyrighted, but rights are hereby granted for photos and videos to be used for personal or educational, non-commercial use in homes, classrooms, seminars, and museums.  Maps and papers from the USGS and Forest Service are free to use, but papers from professional societies and scientific publishers should be fully cited as being from their publishers. What's Are The Sevier and Laramide Orogenies? An "orogeny" is a mountain-building event. The Sevier orogeny took place in the western U.S. between about 140 and 60 million years ago along a band that roughly para...