HIKE 14 Mount Diablo

      Highlight Viewpoint for much of Northern California

      Distance 0.7 mile

      Total Elevation Gain/Loss 100'/100'

      Hiking Time 1 hour

      Recommended Maps Mount Diablo, Los Vaqueros, and Surrounding Parks by Save Mount Diablo, USGS 7.5-min. Clayton

      Best Times After storms

      Agency Mount Diablo State Park

      Difficulty

      DOMINATING THE landscape, Mount Diablo offers vistas from the Sierra Nevada to the Golden Gate in an all-encompassing sweep of Northern California. There is no other view like it.

      Surrounded by encroaching development and connected to no greater mountain range, Mount Diablo is an oasis of both plant and animal life. Besides a variety of wildlife—and particularly birdlife—several plant species occur on the mountain that can be found nowhere else. Due to variations in elevation and precipitation, a variety of ecosystems are found here, and several can be explored on this short hike.

      The Hike follows the Mary Bowerman Trail, an easy loop around the summit of Mount Diablo (3,849') offering spectacular vistas in every compass direction. An interpretive brochure and informative signs enhance the experience. The optimal time to come is immediately following a spring or winter storm when the air is cleanest, the views most far-reaching, and the landscape carpeted a vibrant green. Even then, a good breeze is necessary to blow away all lingering and newly forming clouds, which can hover around the mountain. Strong easterly winds during the spring can also push the haze away. While the hike is open year-round, haze and heat are thick throughout summer and fall. Water is available at the trailhead.

      To Reach the Trailhead Take the Ygnacio Valley Rd. off-ramp from Hwy. 680 in Walnut Creek and proceed 3.8 miles east on Ygnacio Valley Rd. to Oak Grove Rd. Turn right on Oak Grove Rd. and then turn left onto North Gate Rd. in 1 mile. When you reach a junction with Mount Diablo Scenic Rd. at park headquarters 8 miles later, take Summit Rd. 5 miles farther to the summit. Park in the large lot where the lanes divide near the top. It is also possible to approach from the south by taking Diablo Rd. from Hwy. 680 in Danville east for 3 miles to Mount Diablo Scenic Rd. Turn left and proceed up the narrow, twisting road for 6 miles to the junction with Summit Rd., on which you continue 5 miles to the summit. There is a day-use fee of $10 per vehicle.

      Description Be sure to pick up an interpretive brochure at the visitor center before you start. Beginning by the picnic tables across the road from the parking lot, the first half of the hike is paved and passes through a small sample of the oak woodland plant community, offering exceptional views north of distant Mount St. Helena (Hike 36) and northeast across the Sacramento Valley to the Sierra Buttes (Hike 72). Mount Shasta would be visible 240 miles away were it not blocked by the curvature of the earth. Closer to the north is nearby Eagle Peak (Hike 15). The rocks around you are greenstone and chert, the uppermost layers of what is known as an ophiolite suite, a group of rocks and minerals found close together wherever ancient seafloor is exposed.

      The seafloor is composed of five layers. The bottom three form a surface that is essentially a solid piece of the earth’s crust. The upper two layers are deposited underwater on this surface. At tectonic spreading ridges, liquid basalt is squeezed out onto the seafloor, piling up in distinctively shaped pillow basalts, which compose the first of the two upper layers. These are in turn covered by sediment settling from the ocean. Primarily made up of the microscopic skeletons of tiny sea creatures, this silica-rich upper layer takes millions of years to accumulate, gradually forming thin layers mixed with small bits of sand and mud. Altered by pressure and temperature, these two upper layers eventually become greenstone and chert. The Mount Diablo Ophiolite, as it is called, has been so heavily deformed and tilted that the sequence no longer lies flat. While its upper layers are visible at the summit, its lower layers are exposed northwest at the Lone Star Quarry, where diabase, a constituent rock of the lower sequence, is used for roadbeds and foundations. Exactly how this piece of 165-million-year-old seafloor became emplaced in the young sediments ringing Mount Diablo remains a mystery.

      As you hike into chaparral on the drier east slope of the mountain where the path becomes dirt, the peaks of Yosemite National Park (Hikes 85–90) can be identified. Let the gospel flow from atop Devil’s Pulpit, a large outcropping of chert with a mildly precarious scramble to the top. Beyond it, the trail curves onto the south side of the mountain, where grassland replaces the chaparral ecosystem on this sunniest side of the summit. Coyote Hills (Hike 12) can be spotted to the southwest by the bay. The trail ends back by the parking lot.

      Nearest Visitor Center The Summit Museum–Visitor Center, 925-837-6119, constructed on the actual summit of the mountain, is open daily year-round, 10 a.m.–4 p.m. For general information, call 925-837-2525.

      Nearest Campground The park has three year-round campgrounds with a total of 56 sites. Juniper Campground, the largest of the three, is along Summit Rd.; small Junction Campground is by park headquarters; and Live Oak Campground can be found on Mount Diablo Scenic Rd./South Gate Rd. (all campgrounds $30). Reservations are recommended for weekends; visit reserveamerica.com or call 800-444-7275.

      Additional Information mdia.org, savemountdiablo.org, and www.parks.ca.gov

      Summit Visitor Center atop Mount Diablo

      HIKE 15 Eagle Peak

      Highlights Flowers, oaks, and a secluded summit

      Distance 4.0 miles

      Total Elevation Gain/Loss 1,800'/1,800'

      Hiking Time 3–4 hours

      Recommended Maps Mount Diablo, Los Vaqueros, and Surrounding Parks by Save Mount Diablo, USGS 7.5-min. Clayton

      Best Times February–May

      Agency Mount Diablo State Park

      Difficulty

      FROM A SEA OF rippling grassland rises Eagle Peak, a little-visited summit below the ramparts of Mount Diablo.

      The Hike climbs to the summit of Eagle Peak (2,369') from the northern boundary of Mount Diablo State Park, ascending on Mitchell Rock Trail before returning via the Eagle Peak and Coulter Pine Trails. While the hike can be done year-round, spring is the time to come as the land is carpeted green, wildflowers bloom, and temperatures are most ideal. Sections of the trail are exposed, making sun protection crucial most of the year. Ticks and poison oak are of particular concern in the

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