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 10 segments on your computer or mobile device. Presented by Mount Diablo Interpretive Association. First published in 2015, updated in 2018. Featuring Ken Lavin, Rich McDrew, David Mackesey, and Mike Woodring; Music: Phil Heywood; Production, Narration: Joan Hamilton; Photos: Seth Adams, Contra Costa Historical Society, Joan Hamilton, Moose Henderson, Ken Lavin, Conrad Lowry, Mark Sinclair; Special thanks to Anastasia Hobbet, Conrad Lowry, Jennifer Roe, Jerry Schweickert, Mark Sinclair, Stephen Smith. A GPS-enabled map for this tour is available for $1.99 through Avenza Maps at https://www.avenzamaps.com/maps/search.html 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 . . . ​​​​​​​
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.​​​​​​​
What makes the caves in Rock City’s soft sandstone? Hint: it isn’t the wind!​​​​​​​
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.
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.
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!
Stoves built by the Civilian Conservation Corps in the 1930s proved so popular they were used throughout the state and national park system. 
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.
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.

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