"This book is an outgrowth of an undergraduate course I taught for students from Columbia College and Barnard College. My approach was to trace the development of the Earth from its roots in the Big Bang to its future in man?s hands. At each stage I depict the important observational evidence and attempt to show how it has been linked together into hypotheses. I attempt to show that while in some cases this evidence constrains us to a widely accepted single hypothesis, in others the evidence is incomplete and permits a range of competing explanations. It was my hope that in this way I could bring my students to see that science is far from static. Rather, it is a series of ongoing studies where all the evidence, assumptions, and hypotheses are continually being reexamined and where new information is regularly being added. Many readers will surely ask why this book was not published through the the usual channels. Beyond my liking for the unconventional, there is an important financial reason. For each book sold $2.50 will be returned to the Department of Geological Sciences as repayment of typing and drafting costs. After a year of negotiations with various publishers I found this to be the only way I could recover these costs. Thanks to computer layout schemes and laser printers, it is now possible to circumvent the very high overhead associated with conventional publishing. I would like to thank Vicky Costello who patiently typed and retyped the many drafts of this manuscript, and Patty Catanzaro who drafted and redrafted the many figures. I also thank the ten or so scientists who read through the manuscript and made valuable suggestions. Finally I thank the students in Geology 101 lx during the years 1981 to 1985. They were the guinea pigs as well as the inspiration for this project."