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.
Subject: Geoscience:Geology:Igneous and Metamorphic Petrology, Geoscience:Geology Resource Type: Scientific Resources:Overview/Reference Work Topics: Time/Earth History Theme: Teach the Earth:Course Topics:Petrology