Devils Tower, the first National Monument was established by Teddy Roosevelt on 9/24/1906. The tower was made famous by the classic movie (my view): Close Encounters of the Third Kind.
How did the tower form?
Here is the latest explanation thanks to Google AI but there is still disagreement.
Magma Intrusion:
About 50 million years ago, magma, or molten rock, rose from deep within the Earth’s crust and forced its way into the existing sedimentary rock layers.
Cooling and Solidification:
As the magma cooled and solidified underground, it formed an igneous intrusion, which is a mass of rock formed by the cooling of magma.
Columnar Structure
As the magma cooled, it contracted, and these contractions created the characteristic columnar joints, resulting in the distinctive hexagonal columns that are a hallmark of Devils Tower.
Erosion
Over millions of years, the surrounding sedimentary rocks eroded away, exposing the more resistant igneous rock of the intrusion, revealing the iconic tower we see today. The tower will continue to “grow” due to ongoing erosion.
We visited here on the way to Glacier National Park. My most vivid memory is the kids complaining the entire hike. Jenny (far right) looks happy.
HAPPY TRAILS, STEVE