Stephen Marshak is Professor of Geology at the University of Illinois, Urbana-Champaign, where he is also the Director of the School of Earth, Society, and Environment. He holds an A.B. from Cornell University, an M.S. from the University of Arizona, and a Ph.D. from Columbia University. Steve's research interests lie in structural geology and tectonics. This work has taken him into the field on a number of continents. Steve loves teaching and has won his college's and university's highest teaching awards. In addition to research papers and Essentials of Geology, Steve has authored Earth: Portrait of a Planet; and has co-authored Laboratory Manual for Introductory Geology; Earth Structure: An Introduction to Structural Geology and Tectonics; and Basic Methods of Structural Geology.