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Geology of the San Francisco Bay Region by Doris Sloan

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Sloan: Geology of San Francisco Bay Region

Geology of San Francisco Bay Region by Doris Sloan

University of California Press
For residents and visitors alike, this superb field guide will kindle a lasting love affair with the very ground of the Bay Area.


Title: Geology of the San Francisco Bay Region
Author: Doris Sloan
Publisher: University of California Press
ISBN: 0520241266


  • Subject is skillfully presented for all levels of understanding
  • Recent research findings are incorporated
  • Maps, diagrams and photos are of high quality
  • Clear directions and descriptions of many localities
  • Minerals are not treated in detail
  • Page size does not allow large maps
  • Clear introduction to Bay Area geology closely tied to real places
  • Large amount of information presented in compact form
  • Sturdy binding and strong paper for many years of use

Book Review

The San Francisco Bay area is a landscape lover's paradise, full of variety in terrain and climate. It is my native land, and after some time spent elsewhere I've lived there since the mid-1970s. In all that time there has not been a good portable guide to the Bay Area's rocks and geology. Now we have a book worthy of the subject.

Bay Area rocks and hills testify to 200 million years of energetic Earth movement, starting with the scraping and crushing process of plate tectonics called subduction. Once most of California was a sea like that off the coast of Chile, or Japan. Pieces of oceanic crust, seafloor clay, ancient landmasses and floods of coarse sand shed from rising mountains piled up in deep trenches and were turned to rock.

Then plate motions changed, tearing this assemblage sideways into strips and shuffling it like a deck of cards. Volcanic rocks covered the landscape, then more sediments, and then more movements fractured the geologic map. Today the movements continue, more slowly than fingernails grow but swiftly enough that geologists think of the Bay Area as a temporary place.

The Bay Area has yielded treasure of all kinds: gold, gravel, coal, sand, sulfur, mercury, stone, salt, metals. Its soils support timber, orchards, wheat, vineyards, lawns, vegetables, wildflowers. With all the attention it has drawn, Bay Area geology still has been a difficult story to decipher. The plate-tectonic revolution of the 1960s gave us the key to the region's geologic biography, and four more decades of fieldwork and lab studies largely flesh it out.

Doris Sloan, of the University of California at Berkeley, has spent her career in the thick of this ferment and is well qualified to compile Geology of the San Francisco Bay Region, an inviting survey of the nine counties that touch San Francisco Bay. With this guide Bay Area residents can add a new dimension of appreciation to their favorite outdoor recreation whether it's birdwatching, boating, backpacking, botanizing, beachgoing or just poking around the backroads. Now everyone can fall in love with our distinctive chocolate-colored chert, blue-green serpentine and fossil dune fields. Even people stuck in traffic can find things to look at.

Three introductory chapters deftly lay down the Bay Area's basics in good textbook order: its geologic processes, its structural framework and its succession of remarkable rocks. After that come seven chapters that circle the Bay starting in Marin County. Most of these have guides to special localities in public parks, where exceptional geologic features are preserved in their natural setting.

Sloan: Geology of San Francisco Bay Region

Geology of San Francisco Bay Region by Doris Sloan

University of California Press

The clarity of the text is complemented by 137 superb photographs, the bulk of them by John Karachewski (of geoscapesphotography.com), 25 excellent geologic maps, 40 diagrams and a helpful glossary. Ample cross-references and careful editing ensure that readers will not be lost wherever they start reading. This book will support many years of learning, including details to delight geo-fanatics. Even the rock units on the maps have their own special index, so you can find outcrops of the Yolla Bolly Terrane wherever you go. For readers going even deeper, the list of suggested readings is first-rate.

Geology of the San Francisco Bay Region is a worthy host gift for your next visit to Bay Area friends or relatives. Conversely, hosts will find it handy for enriching their guest's stay. This classic guide promises to nourish the roots of a lasting and popular love affair with a special place on Earth.

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