Geology and Physiography of Devil's Tower

This case study was written by Ellen Dockery, a lower division undergraduate student who is not an earth science major, as part of the DLESE Community Services Project: Integrating Research in Education. The pages in this case study reflect the personal views of the student author and not of MSU, SERC or the NSF.
Devils Tower National Monument.
Devils Tower National Monument. Details

Devil's Tower, deemed the first national monument by Theodore Roosevelt in 1906, is an igneous intrusion which rises 1,267 feet above the surrounding area. The redness of the rocks is due to the oxidization of minerals (Devil's Tower National Monument (more info) ). The region around the tower is composed of the Spearfish, Gypsum Spring and Sundance formations (Field Notes (more info) ).

Although Devil's Tower has long been a prominent landmark in northeastern Wyoming, the origin of the mammoth rock obelisk remains somewhat obscure. Geologists agree that Devil's Tower formed from molten rock forced upwards from deep within the earth. Debate continues, however, as to whether the rock cooled underground or whether Devil's Tower magma reached the surface. Current research supports the conclusion that Devil's Tower was not a volcano, but was injected between sedimentary rock layers and cooled underground. The characteristic furrowed columns are the result of contraction which occurred during the cooling of the magma. Geologic estimates have placed the age of Devil's Tower at greater than 50 million years, although it is likely that erosion uncovered the rock formations only one or two million years ago (Field Notes (more info) ).

Prayer Flags near Devils Tower.
Prayer Flags near Devils Tower. Details

Devil's Tower is considered a sacred landmark by more than 20 Native American tribes. The Lakota refer to Devil's Tower as Bear Lodge, and historically used this sacred place for funerals, prayer offerings, sweatlodge ceremonies, as well as their Sun Dance ritual (Devil's Tower: Sacred Place (more info) ). For more information about the sacred ties of Native Americans to Devil's Tower, click here (more info)

Geology of Devil's Tower

Resources about the Geology of Devil's Tower
  • Devil's Tower Geology. This site from the National Park Service briefly addresses the geology of Devil's Tower. The evolution of various theories on the formation of the tower are discussed. A slide show of the emplacement of the tower is also available. (more info)
  • Devil's Tower National Monument. This page is an introduction to Devil's Tower National Monument. Information is provided on the history, Native American folklore, and the geological formation. (more info)
  • Devil's Tower, Wyoming. This page includes topographical maps of Devil's Tower and the surrounding area, as well as photographs of the tower, the local stratigraphy and geology of the region. (more info)
  • Field Notes. This page provides a brief overview of the geology of Devil's Tower. The unique geological attributes of Devil's Tower stimulated several early preservation efforts, which are described on the site. Links to maps of the park and a photo album are also available. (more info)
  • Weird Geology: The Devil's Tower. This page features a brief introduction to the several theories about the geological processes that formed Devil's Tower, which rises 1,267 feet above the nearby Belle Fourche River and is still considered a sacred place by some Native American Tribes. Information on climbing the tower as well as images and a cross section are provided. (more info)

For ideas on how to use these webpages in a classroom, a Study Guide is provided.