Exploring the Rocks & Caves of Castle Rock State Park

Yesterday was a splendid sunny day for my Foothill College class to explore Castle Rock State Park. Carpooling from the Saratoga Library, we arrived just in time to grab the last few parking spaces along Skyline Boulevard. This park has become too popular on weekends for the limited parking now available. A new entrance with additional parking is planned.

From the main entrance we headed downhill on the Saratoga Gap Trail, pausing at a sandstone outcrop to examine the amazing process of "cavernous weathering", which only occurs in parts of the world with a Mediterranean climate. During the wet season, from November through April, rain water seeps into cracks in the rock. Then, during the long dry season, from May through October, the water, with dissolved calcium carbonate, is drawn to the surface to form a hard, erosion resistant, outer layer while the interior of the rock falls apart. That is why these rocks erode from the inside out, forming caves and interesting patterns called tafoni.

We then headed uphill on the Ridge Trail, bursting out of the woodland to reveal spectacular views of the San Lorenzo River Valley and on to the Pacific Ocean and Monterey Bay. After examining Goat Rock from the bottom, we ascended the trail to the uphill side, which can be ascended without technical aid. At least half the class made it to the top of Goat Rock, using various techniques, in order to enjoy the best view in the park. From there we stopped to look at what I call "Amphitheater Rock", which has lots of concretions called "cannonballs", and then headed on to a scenic overlook where we found an acorn woodpecker's granary tree stocked full of acorns for later consumption.

We left the Ridge Trail

to find Hole-in-the-Wall Rock, which has one of my favorite caves in the park. About half the class followed me to the top of the rock and then squeezed down a hole into a hollowed out chamber with a big picture window opening. It looks like a good place to live in case of nuclear war or the collapse of civilization. By then it was time for lunch at a huge canyon live oak with lots of seating in the form of rounded rocks and logs.

After lunch we took the first trail to the left, which connected us with the Saratoga Gap Trail. This trail has lots of sweeping vistas as it passes mostly through chaparral and occasional pockets of bay laurel. Some of the students saw a baby rattlesnake beside the trail. We stopped  briefly to look at Castle Rock Falls, though it isn't much more than a trickle this time of year.

The grand finale was the ascent to the park's namesake, Castle Rock. Some of the students climbed into a shallow cave in the rock while the rest of the class circumnavigated the rock or watched rock climbers practice their sport. This rock is perfect fun for children and adults who never really grew up.

TO GET THERE... The main entrance is on the west side of Skyline Boulevard, about 2.5 miles south of its intersection with Highway 9 (Saratoga Gap).