Geology of Northern California (Classic Reprint)

Explore a dramatic coast-range quarry where ancient rocks reveal deep, nameable minerals.

This field guide entry highlights Laytonville, a landslide site cut into metamorphosed Franciscan rocks. Readers will see how glaucophane-rich metabasalt and interlayered metasedimentary rocks tell a story of high-pressure, long-ago tectonics in Northern California.

The narrative walks you through the quarry's geology and texture. It describes rock color, mineral content, and the relationship between faulting and rock contacts, offering a vivid look at how metamorphism shapes the landscape. Expect clear observations about bedding, foliation, mineral grains, and how these features indicate the rocks’ origins and history.

• Learn how metabasalt gets its blue-gray color from glaucophane and what other minerals accompany it.
• See how metasedimentary rocks appear as narrow interbeds within metachert and how they differ in grain size and composition.
• Understand the role of faults in shaping rock contacts and dip directions visible at the quarry.
• Get a grounded, field-ready sense of how geologists identify and describe metamorphic rock types in the Franciscan sequence.

Ideal for readers of field guides and geology enthusiasts who enjoy hands-on, descriptive rock observations.