Maurice Thorner Memorial Preserve

An easy-going San Geronimo pocket preserve.

Rangers Recommend

  • Rainy season turns the grasslands lush and green.
  • A single, gently sloping trail carries visitors to a low ridge above San Geronimo Valley. Enjoy views of White Hill and Gary Giacomini Preserve on a clear day.
  • Thorner Ridge Trail connects to a bridge that crosses Nicasio Valley Road, providing access to Roy's Redwoods Preserve.
  • For a longer loop hike take Thorner Ridge Trail to French Ranch Preserve, via a brief walk on Lagunitas School Road.
  • The 33-acre preserve was donated by Daniel "Jeff" Thorner, a vice-principal at Terra Linda and San Rafael high schools and a successful businessman.
  • Dogs are welcome, but must be leashed at all times.

Naturalist Notes

  • See madrone, coyote brush, coast live oak, big-leaf maple, California bay, California nutmeg, and hazelnut trees.
  • Spring wildflowers include mariposa lily, and clarkia.
  • Listen for the chatter of woodpeckers.
  • Check out the iNaturalist field guide. Add your own observations.


dog on leash
Dogs On Leash

Know Before You Go

  • Stay on roads and trails to preserve sensitive ecosystems and to avoid trespassing on private property.
  • Dress appropriately for the weather. Trails can be muddy during rainy season. In summer use sun protection–there is no shade.
  • Bring water.
  • There are no restrooms at this location.
  • Steer clear of poison oak.
  • After an outing, check for ticks.