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. Ben A. van der Pluijm is Professor of Geological Sciences and Professor of the Environment at the University of Michigan, Ann Arbor. He is (co-)author of more than 120 research articles and editor/board member of several international journals. His research focuses on brittle and ductile faults, crustal architecture of collisional belts, intraplate deformation, microstructures and textures, and geochronology, with main field areas in North America, South America and Europe. In addition to teaching undergraduate and graduate courses in Geological Sciences, he coordinates Michigan's interdisciplinary Global Change Curriculum and is involved with various technology-supported educational initiatives.