I am grateful to many friends and colleagues not only for help on the present report, but also for help on the two preceding reports which made this one possible. I refer to my Professional Paper 451,[43] which supplied the detailed geologic data and to the first popular-style booklet.[44] First of all, I must acknowledge the great help rendered by members of my family—my eldest son Bill for serving as my unpaid field assistant for most of the detailed mapping of the Grand Junction area, and my two younger sons Terry and Bob for similar services during the last phases of the fieldwork. I am especially indebted to my wife Ruth for material assistance in all the fieldwork, including the road logging and the color photography for the present report. I am grateful to several colleagues of the Geological Survey and National Park Service for help, data, or reviews of all three reports noted, and to members of my family for reviewing both popular-style reports. For reviewing the present report I am especially indebted to David V. Harris, Emeritus Professor of Geology, Colorado State University; Harry A. Tourtelot, Geologist, U.S. Geological Survey, for reviewing both popular-style reports and contributing petrographic studies to the detailed report; and to my wife, Ruth. The comments and criticisms of all reviewers were carefully considered and most were adopted, but in some places I have preferred to state things in my own way, and have included topics that seemingly were of more interest to me than to some of the reviewers. The responsibility for the form and content of this report thus remains mine. References Listed below in alphabetical order are the reports referred to in this report. In the next section are listed reports for additional reading, which I hope will be of general interest to most readers of this report.