The U.S. Geological Survey agreed to publish the proceeding of the first annual William T. Pecora Memorial Symposium in its Professional Paper series because the subject material is related to the mission of the Survey. The usual standards for this series have been modified to accommodate the variety of styles used by the participants in this symposium. All color illustrations are placed at the front of the book for economy in printing. They are identified by the names of the authors of the papers from which they are extracted.