Rock City

A 1.6-mile walk exploring the history, geology, and plants of one of the most popular places in Mount Diablo State Park. Watch and enjoy all 11 podcast segments on your computer or mobile device. Sponsored by Mount Diablo Interpretive Association and Diablo County Club, 2015 Featuring Ken Lavin, Rich McDrew, David Mackesey, and Mike Woodring; Music: Phil Heywood; Narration & Photos: Joan Hamilton (unless otherwise noted); Map: Mike Woodring; Production: Audio Guides to the Outdoors A GPS-enabled map for this tour is available for $1.99 through Avenza Maps at In the search box write Rock City Audio Guide.

What will you learn on this hike? Two flowers. Four ferns. Why the rocks here have holes like Swiss cheese. What Sentinel Rock has in common with Half Dome in Yosemite. And much, much more . . . 
Music: “Hedgehog Hedge,” Some Summer Day, by Phil Heywood. Photos: Diablo Stove, courtesy California State Parks.
Why this tree is named after the surgeon on George Vancouver’s Voyage of Discovery in the 1790s. How and why you can use it today to cool off in the summertime.
Speaker: Ken Lavin, Mount Diablo Interpretive Association
What makes the caves in Rock City’s soft sandstone? Hint: it isn’t the wind!
Speaker: Ken Lavin, Mount Diablo Interpretive Association
Strange as it may seem, the sandstone here is made from weathered bits of of far away Sierra Nevada granite. In this segment, naturalist Ken Lavin explains how that happened and helps us recognize the granite’s constituent parts, including quartz, feldspar, biotite and hornblende.

Music: “Vermilion,” Rollin’ On, by Phil Heywood. Photos: historic photos courtesy of Contra Costa County Historical Society; concentric circles of hornblende and biotite, courtesy of Ken Lavin.
On this stretch of the trail, you’ll walk past wood, polypody, goldenback, and maidenhair ferns. Ken shows us how to make a spore print en route. In springtime you might also see two impressive early-blooming flowers: Indian warrior and mission bells. Each has an interesting story.
Speaker: Ken Lavin, Mount Diablo Interpretive Association

Who was Dan Cook? A successful miner from Bodie who owned a big chunk of the mountain in the late 1870s and early 1880s. His history connects with that of California’s Big Four Railroad Barons and Robert Noble Burgess, who, much later, built North and South Gate roads, for auto racing!
Speaker: Ken Lavin, Mount Diablo Interpretive Association
These stoves, build by the Civilian Conservation Corps in the 1930s, proved so popular they were used throughout the state and national park system. 
Music: “Tomato Truck,” Rollin’ On, by Phil Heywood. Photos: historic photos courtesy of California State Parks and Contra Costa County Historical Society
Rock City has clear evidence that Native Americans came here to process their acorns. Their grinding holes go back 5,000 years, perhaps even more--older than the pyramids at Giza.
Speakers Ken Lavin, Rich McDrew, Mount Diablo Interpretive Association
The name "Elephant Rock" dates back to the early 1900s, when tourists knew Rock City as the Garden of the Jungle Gods. So there’s a lot of history here, as well as some interesting geology.
Enjoy the view as Ken Lavin tells the hilarious story of Mount Diablo State Park’s second dedication ceremony.
Music: “Vermilion,” Rollin’ On, by Phil Heywood. Historic photos courtesy of Contra Costa County Historical Society.
Speaker: David MacKesey, Diablo Country Club
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