Planet Earth was formed roughly 4.6 billion years ago. For human beings—used to measuring time in terms of days, weeks, and months—such an enormous span of time can be a difficult concept to grasp. Geologists, scientists who study the Earth and the processes that continue to shape it, have broken up this vast expanse of “deep time” into major divisions based on what they have learned from the study of ancient rocks and fossils. The first of these divisions—from approximately 4.6 billion until 542 million years ago—is known as the Precambrian, meaning everything that happened before the Cambrian period. (Today some people prefer to call this period the Cryptozoic, which means “hidden life.”) Almost all of planet Earth’s history is Precambrian. Until recently, however, it has remained the most unknown, the strangest, and most perplexing period in all geologic

history—what some have referred to as the “Dark Ages” of Earth’s existence. <...>

The basic principles of geodesy are presented in an elementary form. The formation of geodetic datums is introduced and the necessity of connecting or joining datums is discussed. Methods used to connect independent geodetic systems to a single world reference system are discussed, including the role of gravity data. The 1983 edition of this publication contains an expanded discussion of satellite and related technological applications to geodesy and an updated description of the World Geodetic System. <...>

The plate tectonic model provides a framework for understanding many geodynamic processes. Earthquakes, volcanism, and mountain building are examples. The plate velocities, 10– 100 mm yr−1, imply a fluid-like behavior of the solid Earth. Hot mantle rock can flow (behave as a fluid) on geological time scales due to solid-state creep and thermal convection. The hot mantle rock is cooled by heat loss to the Earth’s surface resulting in a cold thermal “boundary layer.” This boundary layer is rigid and is referred to as the lithosphere. The surface lithosphere is broken into a series of plates that are in relative motion with respect to each other. This motion results in “plate tectonics.”

This book is a reflection of my enthusiasm for the quantitative treatment of geological problems. However, I am originally a field geologist and over the years I had to rely on the help of many who are more numerically literate than myself to teach me the wonders of quantitative geodynamics. Many of those are acknowledged in the first edition of this book. Of those who helped me with this 2nd edition, my special thanks go to S Hergarten and J Robl.