Devils Tower is a monolithic igneous intrusion in the Black Hills of Crook County, Wyoming, rising about 386 meters above the Belle Fourche River. It formed roughly 40 million years ago when magma intruded into sedimentary rock and cooled underground, later exposed at the surface by erosion of the softer surrounding rock. The tower is famous for its columnar jointing: as the igneous rock cooled and contracted, it fractured into mostly hexagonal columns, among the most physically striking examples of columnar jointing on Earth. Geologists debate whether the rock body is the neck of an extinct volcano or a laccolith or stock that never reached the surface; in 1906 it became the first United States National Monument.
Facts
Classification
Protected StatusNational Monument or Landmark 1 FAQs
Is Devils Tower the neck of an old volcano?
Not settled: geologists agree it began as buried magma but still debate whether it is a stock, a laccolith or a volcanic neck.
Geologists have not settled that. They agree that the tower began as magma buried beneath the Earth's surface, but they disagree about how it cooled and how it relates to the surrounding rock. The simplest explanation is that it is a stock, a small intrusive body that cooled underground and was later exposed by erosion. Early twentieth century geologists treated it as the eroded remnant of a laccolith, a mushroom-shaped igneous mass that never reaches the surface. Others have proposed a volcanic plug or the neck of an extinct volcano, but the area shows little volcanic ash, lava or debris, which creates doubt that the tower was part of a volcanic system.
Connections
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Found In
Also in Geography Atlas: where this subject is found.
Sources
1. Wikipedia: Devils Tower - Wikipedia
U.S. historyQuote, U.S. history
in 1906, Devils Tower became the nation's first national monument.
Wikidata: Devils Tower
Wikidata Q306201, class allow-list match (w-wdresolver-0926)View the Source Reader Challenges (0)
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