Devils Tower

Devils Tower is a prominent igneous rock formation in northeastern Wyoming and the centerpiece of Devils Tower National Monument. Its steep sides are marked by tall, polygonal columns formed as magma cooled.

Columnar jointing: A fracture pattern formed when cooling rock contracts into polygonal columns. The Tower’s vertical columns are a dramatic example of this cooling-related fracture pattern.
Black Hills: An isolated mountain range spanning western South Dakota and northeastern Wyoming. The Tower stands near the Black Hills, within the region’s broader geological setting.
Devils Tower National Monument: A United States national monument in northeastern Wyoming established to protect Devils Tower and its surroundings. The monument protects the formation and the landscape immediately around it.
Lakota people: An Indigenous people of the Great Plains, historically part of the Oceti Sakowin. Lakota traditions connect the Tower to sacred narratives and continuing cultural practice.
Phonolite porphyry: An igneous rock containing large crystals in a finer-grained groundmass, with phonolite composition. This rock type describes the Tower’s distinctive intrusive material.
Laramide orogeny: A mountain-building episode that uplifted parts of western North America during the Late Cretaceous and early Paleogene. Regional uplift and deformation shaped the rocks surrounding the Tower.
Columnar basalt: Basalt displaying polygonal columns formed as lava cools and contracts. Its familiar columns invite comparison, but Devils Tower is not basalt.
Bear Lodge: A name associated with Devils Tower in Indigenous traditions and with the nearby landscape. The name reflects Indigenous relationships to the formation that differ from its English name.
Magma: Molten or partially molten rock beneath Earth’s surface, containing dissolved gases and crystals. The Tower formed from magma that cooled underground.
Paleocene: The geological epoch from about 66 to 56 million years ago, following the Cretaceous Period. Some formation models place the Tower’s emplacement during this epoch.

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Volcanic plugBroader topic: Its origin as a volcanic plug or shallow intrusion remains debated.