Enjoy a 1.6-mile walk exploring the history, geology, and plants of one of the most popular places in Mount Diablo State Park. Featuring Ken Lavin, Rich McDrew, 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.