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Best of Shell Ridge Loop Hike





by Transit & Trails


Wildlife Sightings

by iNaturalist


Length: 5.78 miles
Difficulty: Moderate
Duration: Halfday
Created by Ken Dyleski

Ken Dyleski helps Save Mount Diablo with mapping and on-the-ground stewardship work. He collaborated on producing the first edition of the Mt. Diablo map published by Save Mt. Diablo. His GPS enabled digital trail map of the Diablo Grand Loop was published on the National Geographic Topo site. He has a California State Certificate in Geographic Information Science from Diablo Valley College. Mr. Dyleski's previous articles on the outdoors have been published in Sierra magazine, Northern California Explorer, and the Tahoe Daily Tribune.

Good for:
  • Views
  • Wildflowers
  • Forests and Woodlands
  • Grasslands
  • Urban Hiking


Growing ever more popular since the 1974 bond measure passed that gave it life, Walnut Creek’s Shell Ridge Open Space offers more than a nostalgic stroll through an undulating landscape that is little changed since “simpler times”.

Named for the former sea bed fossils found from ridge top to creek bottom, an evolutionary timeline is clearly in progress here. Perhaps the most interesting changes are those that have been recently occurring over the last 150 years.  Prepare yourself for looking at the topography with an inquiring mind.  Pick up a copy of the Walnut Creek Open Space map from the city office front desk (for free) at 1666 N. Main.  You will find the trails and important features referred to in this hike clearly marked.

Plan ahead as there is only one place with potable water: Borges Ranch at the half way point.  Be forewarned so as to carry plenty of iced water on warm days.  Due to a recent banner water season, the rodent population has been provided with ample food and rattlesnakes are estimated to be present in record numbers resulting from rodent feasting.  Walk slowly on the single track trail, staying aware of the path ahead; using extra caution approaching rocks and logs!           

Begin the route by parking at the dead end of Marshall Dr. near Indian Valley School. Enter the Open Space on a dirt trail and veer left around the actual Shell Ridge.  Pick up the signed Ridge Trail and enter the single track.  If you walk in the early morning during the week, this hike will avoid both crowding and the heat of dry season.  Follow the trail through occasional easy switchbacks, enjoying the nice views on this quieter N.E. side of the ridgeline.  Take a break on the ridge top with a view down into the canyon on the opposite S.W. side of the ridge.  The fire road below runs mostly parallel to Shell Ridge and is named the Briones-to-Diablo Trail on your map.  After reaching Mt. Diablo State Park, this particular trail changes its name as it continues onward for a total of 30 miles to Round Valley Regional Park.  This is a great example of trails also acting as wild life corridors linking islands of animal and plant habitats.  These corridors are designed to be a form of mitigation for the habitat fragmentation that results from recent poorly planned real estate growth.

The oak woodlands that you see scattered in all directions around you have more biodiversity than any other major habitat in the state according to researchers at the University of California.  It is documented that for at least 100 years, certain oak species are not regenerating for their own sustainability.  Perhaps you have noticed young oaks growing in wire cages or sticking out of plastic tubing during this hike.  In 1991, an oak regeneration project was started by Walnut Creek Open Space and turned over to the Open Space Foundation for management.  To date, approximately 700 trees have been planted.

After appreciating this high altitude overview of the recreational area, continue the hike, following the Ridge Trail as it descends to a gate through the fence.  Continue straight ahead and do not pass through the second gate in a fence line on the left.  Soon, you’ll reach another Briones-to-Diablo Trail intersection and sign; here you will head left to the nearby Old Borges Ranch Trail.  A short walk downhill brings you to this turn of the century working ranch listed on the National Registry of Historic Places.  Just past the ranch house on the left, nestled under the trees, is a surprisingly cool picnic area with tables, restrooms and cold potable water.

Return to the trail head by retracing steps just to the Briones-to-Diablo trail.  Follow it, finding your self walking on a more steeply downhill trail.  Look for a “difficult to see” sign close by on your left announcing the Indian Creek Trail.  It’s cooler and quieter in this part of the loop as you walk around and under wonderful twisted oaks, along pond shorelines and past white limestone rocks containing remains of sea shell fossils.  Walk up a short wooden staircase protecting the bank from erosion and take a break at the bench.  It’s a marvel at how remote it feels here, knowing nearly 7 million people reside nearby in the Greater Bay Area within an hours drive!

Indian Creek Trail quickly veers right, intersecting back into the Briones-to-Diablo trail, where you will turn left and in a brief moment you arrive at your car. This hike is especially nice in the Fall when the heat of Summer is gone and the trees show their varied Fall colors.


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