The Rockies and North American Highlands

The Rocky Mountains stretch roughly 4,800 kilometers from northern British Columbia and the Yukon down through the western United States to New Mexico, forming the backbone of the North American Cordillera. Their formation, the Laramide orogeny, took place between roughly 80 and 55 million years ago during the Late Cretaceous and early Paleogene, and is geologically unusual: rather than the steep subduction typical of most mountain-building, the Farallon Plate is thought to have subducted at a very low, "flat-slab" angle beneath the North American continent, dragging basement rock upward far inland and producing uplift hundreds of kilometers from the coastal plate boundary rather than concentrated near it. The range's highest point, Mount Elbert in Colorado, reaches 4,401 meters, and the chain carries the Continental Divide, the drainage boundary separating rivers flowing toward the Pacific from those flowing toward the Atlantic and Arctic, meeting at a rare triple divide near Triple Divide Peak in Montana's Glacier National Park.