The Wonder Jutting 867 feet from base to summit, Wyoming’s Devils Tower formed 50 to 60 million years ago, when magma welled up through sandstone and cooled, producing six-sided vertical columns of grayish, igneous rock. Erosion eventually revealed the tower, which President Theodore Roosevelt named a monument in 1906.
The Way Take the Red Beds Trail for an uncrowded, three-mile dirt-and-gravel loop. Wind .5 mile through a ponderosa forest to a meadow, and look south for tower views. Switchback down 400 vertical feet to tread on the Spearfish Formation’s layer of rust-red, 225-million-year-old sedimentary rock. At 1.8 miles, look left for Belle Fourche River views. Return through the pines. nps.gov/deto