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See map, below



<1 mile

Mary Bowerman Trail





Access on north side of road beside small

picnic site where Summit Road splits into two one-way routes just past exit to Lower Summit Parking Lot. Drinking water and toilets at lower summit parking lot.

Less than a one mile flat loop trail encircling


the summit of the mountain. Allow half hour without stops. The first one third is paved and is ADA accessible up to the Ransome Point overlook.

DESCRIPTION:  This easy trail offers spectacular views as well as a journey through time. Discover how nature has created and altered this peak. There are 14 stops, following the Mary Bowerman Trail Guide (PDF) which can be obtained at the Summit Visitor Center or picked up at the trailhead.

This will guide you through the diverse flora, fauna, geology and weather which embraces Mt. Diablo's summit. You will be introduced to chamise, yerba santa, California native juniper, scrub oak and poison oak. Being careful not to step on the sagebrush lizard as you skirt the summit, you'll come across Devil's Pulpit, a great red-colored monolith, made of chert. Greenstone, an altered submarine volcanic rock laid down on the ocean floor, over 100 million years ago, is the most common rock exposed on the summit of the mountain. Banded red chert, blocky greywacke sandstone and patches of shale are also present along the route.

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