Devil’s Tower was the first United States national monument, established on September 24, 1906, by President Theodore Roosevelt.
The name Devil’s Tower originated in 1875 during an expedition led by Colonel Richard Irving Dodge, when his interpreter reportedly misinterpreted a native name to mean “Bad God’s Tower”.
Native American names for the monolith include “Bear’s House” or “Bear’s Lodge”; Cheyenne, Lakota Matȟó Thípila, Crow Daxpitcheeaasáao “Home of Bears”), “Aloft on a Rock” (Kiowa), “Tree Rock”, “Great Gray Horn”, and “Brown Buffalo Horn” (Lakota Ptehé Ǧí).
We always called it Bear’s Lodge.
The igneous material that forms the Bear’s Lodge is a phonolite porphyry intruded about 40.5 million years ago. The tower did not visibly protrude out of the landscape until the overlying sedimentary rocks eroded away. As the elements wore down the softer sandstones and shales, the more resistant igneous rock making up the tower survived the erosional forces. As a result, the gray columns began to appear as an isolated mass above the landscape.
As rain and snow continue to erode the sedimentary rocks surrounding the Tower’s base, more of Bear’s Lodge will be exposed. Nonetheless, the exposed portions of the Tower still experience certain amounts of erosion.