Geology of Devils Tower National Monument, Wyoming A Contribution to General Geology

Rising abruptly from the prairie, Devils Tower is a striking natural landmark that has fascinated visitors for generations. This carefully researched study invites listeners into the rock‑filled story of the monument, beginning with a clear overview of its location, history, and the reasons it was set aside as America’s first national monument. The opening sections lay out the basic terminology of igneous and sedimentary rocks, setting the stage for a deeper dive into the tower’s unique composition.

The narrative then follows the meticulous mapping work of the 1950s, describing the phonolite porphyry that forms the tower’s columnar silhouette and the polygonal joints that carve its vertical lines. Around the base, colorful layers of sandstone, shale, gypsum and limestone—spanning Triassic to Late Jurassic ages—are explained in vivid, accessible detail. Listeners learn how differing erosion rates sculpted the dramatic contrast between the dark, resilient tower and the bright, softer strata that frame it, offering a clear picture of the geological forces that shaped this iconic feature.