"San Francisco Bay is a shallow estuary surrounded by a large population center. The forces that built it began with plate tectonics and involved the collision of the Pacific and North American plates and the subduction of the Juan de Fuka plate. Changes in the climate resulting from the last ice age yielded lower and then higher sea levels. Human activity influenced the Bay. Gold mining during the California gold rush sent masses of slit into the Bay. Humans have also built several major cities and filled significant parts of the Bay. This book describes the natural history and evolution of the SF Bay Area over the last 50 million years through the present and into the future"--