J. Keith Rigby Jr. was an associate professor of civil engineering and geological sciences at the University of Notre Dame when this was written. A native of Salt Lake City, Rigby graduated from Brigham Young University in 1971 and earned his master’s and doctoral degrees in geology from Columbia University in 1974 and 1977, respectively. He joined the Notre Dame faculty in 1982. A paleontologist, Rigby taught Notre Dame courses in physical geology, historical geology, environmental geology, sedimentation, and stratigraphy. He also lectured on these and other subjects nationwide and abroad. Rigby and his wife, Susan, have six children.