I've continued exploring alternate entry points to Mount Diablo. For now, Lime Ridge Open Space is not one of them. A Mount Diablo advocacy group bought the land between the two parks in 2006 but has kept it fenced off to date. What's taking so long to open the gate?
Transit: The park is a pleasant bike ride from Walnut Creek BART station. Take the Ygnacio Canal Trail east from John Muir Medical Center, a low-use, smooth paved trail through residential areas accompanied by fragrant flowers and mallard ducks. From the bike trail there's a quarter-mile low grade climb to the trailhead, but traffic was light on a Saturday and I reached 24 mph according to radar on the way down.
The Park: Lime Ridge itself is quite delightful, despite being next to a golf course and shooting range. The rocky land is crisscrossed by informal bike trails. Sloppily-signed park trails circumscribe the many ridges and hills. Refer to the map at the trailhead because the hills block line of vision and I dead ended at the park's edge several times. I encountered only a couple bikers at great distance and a few hikers -- very light use for a Saturday.
The light-colored sedimentary rock accumulated from Sierra Nevada runoff 45 million years ago (mya) and was uplifted with Mount Diablo. The layered ridges result from this geologically slow lifting action with erosion of softer rocks. That linked site claims there are still hot springs there which add limestone and dolomite to the rock crevices, completing the ingredients for marble such as prized Italian Travertine. In this case they didn't bake in the pressure cooking part of the Earth's crust, so marble didn't form.
Wildlife: Wildflowers were in bloom in a rainbow of blue dicks, orange poppies, deep purple lupine, and pink. Smell the tiny pineapple weed at the trailhead -- they are a chamomile relative. I napped under a wonderful old oak tree, cushioned by leaf litter, then wildcrafted a big bag of stinging nettle for dinner and tea. Yum, thanks!
I saw my first California Horned Lizard when it scuttled away, then stopped to peer back at me with its tiny eye. There were plenty of other lizards, mesmerizing birdsongs, California quail, and butterflies and dragonflies. Pollinators will soon mob the buckeye trees, whose flower clusters are just budding now. A park sign warns of big predators but I was only there midday.
Preparation: Most of the park is quite exposed, so bring sunblock and a hat, and expect to get grit in your mouth. Because of the looping pattern of the trails, novice hikers should time themselves carefully. There was a port-a-potty in good condition at the trailhead with wash station.