Geologists Just Found Out What Wyoming’s Devils Tower Actually Is

Devils Tower: What Is Known and What Remains Disputed

The video reviews the evidence about Devils Tower, also called Bear Lodge. It emphasizes that the formation is neither a petrified tree nor a definitively understood “volcanic plug.”

Rock Composition and Formation

Devils Tower is made of igneous phonolite porphyry, with large feldspar crystals in a finer-grained matrix. Its columns are mostly pentagonal, rather than the commonly claimed hexagonal shape. Their size and crystalline texture are inconsistent with petrified wood.

Geologists have proposed several ways the tower may have formed: as an underground intrusion, a laccolith that pushed overlying rock into a dome, or lava that filled a crater and later cooled. The mechanism remains unresolved, in part because erosion removed much of the surrounding evidence.

Evidence in the Surrounding Layers

A 1956 U.S. Geological Survey report described sedimentary layers near the tower as dipping inward toward it, while layers farther away dip outward. This pattern is difficult to reconcile with the usual laccolith model, which predicts layers tilting away from the center. The video presents the observation as a possible fit for a collapsed crater.

A 2015 study compared Devils Tower with a phonolite formation in the Czech Republic. Its researchers proposed that an interaction between magma and groundwater blasted out a crater, which was later filled by thick lava. They argued that the tower’s flared lower columns and the inward-dipping surrounding layers support this explanation. However, it remains a hypothesis: direct evidence is limited, and sampling at the site is restricted.

Age and Column Formation

The long-cited age of about 40.5 million years came from potassium–argon dating. Argon–argon results presented in 2002 gave ages of about 49.04 million years for Devils Tower and 49.24 million years for the nearby Missouri Buttes. Because the newer results appeared in a conference abstract rather than a full peer-reviewed paper, different figures continued to circulate. The National Park Service now rounds the tower’s age to about 50 million years.

A 2018 laboratory experiment on basalt found that column-forming cracks developed after the rock had solidified, at roughly 840–890°C. The experiment was not conducted on Devils Tower’s phonolite, so it illustrates a general process rather than directly measuring the temperature at which the tower cracked. The video describes the columns as evidence of slow cooling in a large mass of rock.

The Tower’s Movement

A University of Utah study used seismometers to record the tower’s natural vibrations. Devils Tower resonates at approximately 1.1 and 1.2 cycles per second, with two swaying motions in perpendicular directions and a twisting motion. These movements are tiny—fractions of a millimeter—and occur even without wind, though wind strengthens the shaking.

The measurements could help researchers assess how the tower might respond to earthquakes and identify which parts may be more vulnerable.

Cultural and Naming Context

The video notes that Devils Tower is sacred to more than 20 Native nations and is also known as Bear Lodge. In Kiowa tradition, the vertical grooves are claw marks left by a bear.

According to the video, the English name followed an 1875 expedition and an interpreter’s rendering; Colonel Richard Irving Dodge later shortened it. The history of the name remains contested. A federal advisory committee recommended restoring “Bear Lodge” in 2024, but the committee was terminated in 2025.

Main Takeaway

The tower’s composition, great age, columnar structure, erosion, and present-day vibration are supported by observations. Whether it formed deep underground or in a near-surface crater remains uncertain.

Researchers and Sources Featured

• Franklin Carpenter — Called the formation a volcanic neck in 1888.
• Nelson Darton and Cleopus O’Hara — Argued for a laccolith interpretation in 1907.
• Charles Robinson — Author of a 1956 U.S. Geological Survey bulletin documenting the surrounding rock layers.
• ProPop Zavvada (name as rendered in the subtitles) and colleagues — Authors of the 2015 Geosphere study proposing a crater-and-lava model.
• Jeffrey Moore and colleagues at the University of Utah — Led the seismometer study published in GSA Today in 2026.
• University of Liverpool research team — Conducted the 2018 basalt-cooling experiment; individual researchers are not named in the subtitles.
• Researchers presenting the 2002 argon–argon dating results — Not named in the subtitles.
• Other cited sources — The U.S. Geological Survey, the National Park Service, the Geological Society of America, and traditional accounts from the Kiowa and other Native nations.
• Additional historical and cultural figures — Chief Arville Looking Horse, Colonel Richard Irving Dodge, and Theodore Roosevelt.