Geo-geek Andrew Alden explores the craggy crannies of Oakland that are invisible to most of us. You might think a blog about rocks would make for some pretty yawn-inducing reading, but Alden succinctly describes headscarps, wacke, and serpentinite with an obvious passion for his chosen field. At times the narrative almost resembles poetry, as when he describes a brown mudstone excavation on Skyline Boulevard: “The dark layer is as creamy as chocolate between the teeth. As I stood there, the rattle of falling pebbles was nearly constant.” Too bad some unlucky soul in the Montclair hills is building a doomed garage atop this shaky foundation. Those who enjoy a daily dose of panic (or reality, depending on your perspective) should peruse the “Oakland hazards” and “Hayward fault” categories. Alden’s notes on acid mine drainage, dam failures, forest fires, and the impending Big One make for some hair-raising reading about the Bay Area’s shaky state.