The San Francisco Bay Area's crazy quilt-pattern of rock formations -- shaped by earthquakes -- are the key to understanding the region's landscapes. From ice-age dune sand in San Francisco to recently subsided land in the Santa Clara Valley or the veritable maze of earthquake faults in the East Bay, the geology is a fascinating blueprint of the region's natural history.

Walking the Line

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It was 140 years ago, in October 1868, that the Hayward Fault unleashed the magnitude 6.8 temblor that put the fault on the map. The quake shook the entire region and virtually leveled the then-small hamlets of Hayward and San Leandro. Now, the land along the fault line is among the most densely populated in the region, a sobering situation given the likelihood of a repeat performance in the near future. But despite their destructive potential, the Hayward and the Bay Area’s other faults are the driving force behind our region’s varied and beautiful topography. Understanding how they work is key both to understanding our local landscapes and to preparing for the next Big One.

Black Coal, Bright Flowers

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The peaceful hills of Black Diamond Mines Regional Preserve weren’t always so: One hundred twenty years ago, you’d have found bustling towns full of miners and their families and, nearby, the mine works and railroads that carried out tons of coal and sand, feeding the booming industries of Northern California. Today, the park offers grand vistas, abundant wildflowers, and a mine tour that gives an illuminating view of both the work of the miners and the geological history that brought them here and shaped the aboveground landscape.

Shifting Sands

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At the mouth of Tomales Bay, sand dunes and seasonal wetlands coexist uneasily with California’s largest coastal campground. The dunes at Lawson’s Landing, home to rare butterflies and plants like the dune tansy, are among the few left of a once-common coastal habitat that could be restored and maintained as a healthy, functioning ecosystem. But can that be accomplished without driving out the family-run camping operation at the dunes that, since 1957, has been an affordable summer getaway for thousands of visitors?

The Fremont Peak Experience

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Discover rare rocks, distant stars, beautiful wildflowers, and a bit of California history all at one small state park south of San Juan Bautista.

The Checkerspot Comes Home

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Contrary to common notions of autumn as a season of dying back, our fall rains often herald new beginnings. That’s especially true this fall at Edgewood County Park and Natural Preserve in Redwood City. For the first time since 2002, … Read more

Speak of the Devil

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Mount Diablo is such a towering icon of our landscape that it is sometimes easy to forget how much complexity lies within its familiar outline. Indeed, the mountain holds many stories: from the drama of its birth under the ocean, to its (mis)naming by early American settlers, to last year’s rediscovery of the rare Mount Diablo buckwheat. Today the story continues, with the mountain and its surrounding ridges and canyons anchoring a bold vision for a broad swath of protected open space and wildlife corridors stretching from Concord to Livermore.

The Rock in the Redwoods

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Take a hike to a scene of otherworldly geology, hidden away in this Peninsula preserve’s forests of tanoak, Douglas-fir, and second-growth redwood.

Tafoni Around the Bay

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The tafoni weathering formation featured at El Corte de Madera Creek Preserve is a particularly accessible example of an uncommon phenomenon, but there are several other places to see tafoni in the Bay Area. At Castle Rock State Park west … Read more