We extend our sincere thanks to the authors of the papers in this volume for their interesting and timely contributions to this memoir. Many thanks also to AAPG, and especially the publications staff, who were invaluable in resolving many of the logistical issues faced by both the editors and the authors of the volume. We also extend our thanks to Tony Sandomierski for assistance with figures and Susan Friel of Biotechwrite for editorial suggestions. Lastly, we would like to thank the following individuals, whose critical reviews of the manuscripts assured us of high quality and comprehensive compilations of current progress in this rapidly changing field of study: Rick Abegg, Dave Barnes, Jennifer Beall, Terry Belsher, Jim Borer, Jean Borgomono, Bryan Bracken, Trevor Burchette, Mary Carr, Chris Crescini, Tim Cross, Steve Dorobek, Evan Franseen, Ray Garber, Jean Hsieh, Jim Jennings, Chris Kendall, Charlie Kerans, Rebecca Latimer, Marge Levy, Bob Lindsay, Susan Longacre, Jerry Lucia, Sal Mazzullo, Tim McHargue, Bill Morgan, John Pendrel, Carlos Pirmez, Mike Pope, Dennis Prezbindowski, Gene Rankey, Will Schweller, and John Weisenberger.