Stephen Marshak is Professor of Geology and Head of the Department of Geology at the University of Illinois, Urbana-Champaign. He holds a Ph.D. from Columbia University, an M.S. from the University of Arizona, and a B.A. from Cornell University. He has served as Chair of the Division of Structural Geology and Tectonics of the Geological Society of America. Dr. Marshak has written numerous research articles on topics in structural geology and tectonics, and has authored or co-authored three other books: Basic Methods of Structural Geology; Earth Structure: An Introduction to Structural Geology and Tectonics; and Essentials of Geology.