If you’re lucky enough to find Macedo Ranch, you probably won’t have trouble finding parking. The location at the western foot of Mount Diablo State Park isn’t advertised much. There is no sign directing you down the street of single-family houses in the small town of Alamo. Yet Macedo Ranch is a favorite for locals in the know, including equestrians, mountain bikers, and runners.
After you arrive at the Macedo Ranch staging area, one trail option among many is a four-mile, moderately difficult loop. You’ll pass (usually dry) creeks, bright green or gold hills depending on the season, wide open fields, and the prominent yellow sandstone of Mammoth Rock. Ranchers have a permit to graze cattle around here, and you’ll see the white-faced animals everywhere, their bones littering the ravines. Some portions are a little steep, hot, and unshaded, or muddy and holed with hoofprints after a rain.
The foothills of Mount Diablo will also satisfy geology enthusiasts. For millions of years, different types of sediments piled up at the bottom of the ocean. Eventually tectonic forces lifted Mount Diablo out of the water and turned those layers sideways, exposing a story of time and seams of ancient seashells. Some areas look like a layer cake sliced open. Noticeable on the Briones to Mount Diablo trail is “China Wall,” a line of rock that juts out of the landscape, forming a long feature resembling the Great Wall of China.