How Did the Tower Form? - Devils Tower, WY
Posted by: Groundspeak Premium Member QuarrellaDeVil
N 44° 35.399 W 104° 43.062
13T E 522407 N 4937442
A National Park Service/U.S. Department of the Interior interpretive sign stands along the Tower Trail, providing three explanations as to how Devils Tower was formed.
Waymark Code: WM135P3
Location: Wyoming, United States
Date Posted: 09/21/2020
Published By:Groundspeak Premium Member YoSam.
Views: 5

Below the main text are the three theories about the tower's formation, with corresponding graphics that aren't too terribly different from each other. The sign reads:

The process began about 50 million years ago. Magma (molten rock) was injected into layers of sedimentary rock, forming the Tower one and one-half miles below the earth's surface. It has since taken millions of years to erode away the surrounding sedimentary rock to expose the Tower we see today.

Geologists agree the Tower is an igneous (hardened magma) intrusion, but have three different interpretations of the Tower's original size and shape. Because of erosion, we may never know which interpretation is correct.

Three Possible Interpretations

Igneous Stock:

The Tower is an irregularly shaped, igneous intrusion called a stock. It was formed when magma cooled and crystallized before reaching the earth's surface.


The Tower is the remnant of a mushroom-shaped, igneous intrusion. As with the igneous stock, the magma solidified before reaching the earth's surface.

Volcanic Plug

The Tower is a cylinder-shaped igneous intrusion, part of the plumbing system that fed a volcano. The pipe feeding the volcano became plugged when the magma solidified underground.
Marker Name: How Did the Tower Form?

Marker Type: Rural Roadside

Addtional Information:
Re Mi Do Do So

Group Responsible for Placement: National Park Service/U.S. Department of the Interior

Web link(s) for additional information: [Web Link]

Date Dedicated: Not listed

Marker Number: Not listed

Visit Instructions:
Please post a photo of you OR your GPS at the marker location. Also if you know of any additional links not already mentioned about this bit of Wyoming history please include that in your log.
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