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Science and Nature

“Tamalpais, beautiful coastal mountain, rising from Pacific waves and falling into bayside marshes. Crowned in silver rock and wreathed in manzanita. Grassy slopes and twisted laurels face eastern winds, fires grow on moist north slopes, redwoods in canyons. Above summer’s bright fog roof, down southern and eastern flanks, a chaparral cloak of miniature trees, and everywhere in spring a world of flowers.”
                                   - Tom Killion, Tamalpais Walking: Poetry, History, and Prints

Geology

Mount Tamalpais lies just east of the San Andreas Fault near the border of the Pacific and the North American tectonic plates. Pressures at this plate boundary have pushed the mountain (and the rest of the Coast Range) up from Earth’s crust, while erosion has left solid rock exposed in the highest peaks and ridges.
Common rock types include shale, chert, graywacke sandstone, greenstone (pillow basalt), quartz tourmaline, and the easily identified green serpentine, California’s official state rock.

East Peak sign

The park’s highest point is 2,571-foot East Peak.

Plants

The varied topography and soils of the park support more than 750 plant species. Hikers pass through open grassland, chaparral and oak-covered knolls, dense stands of Douglas-fir and California laurel, and deep redwood-filled canyons.

In spring, Mount Tam comes alive with wildflowers. Hillsides are sprinkled with brightly colored California poppies, lupines, Douglas irises, goldfields and shooting stars. Spotted coralroot, fetid adder’s tongue and Pacific trillium hide in the deep shade of the forest. In springtime, look for pink-to-purple calypso orchids.

Flowers


Along Webb Creek, the Steep Ravine Trail leads hikers through a stand of coast redwoods. The sound of rushing water, the smell of damp earth, the sight of ferns and wildflowers are part of any walk beneath the redwood canopy.

The size and longevity of redwoods helps them store more climate-altering carbon dioxide than other plants. Even old redwoods continue to grow, each year adding more carbon-filled wood than smaller, younger trees. After redwoods die, their rot-resistant wood holds onto that carbon for a long time.

More information about local plants is available on the Friends of Mt. Tam website, where you can download color brochures on chaparral, rare plants, and flowers. Flowers of Marin is also an informative blog.

Wildlife

Mammals
Raccoons, gray foxes, squirrels, bobcats, coyotes, black-tailed deer and mountain lions all live on Mount Tam. Black bears and elk once wandered here as well, but they vanished as a result of hunting and ranching before the park was established.

Many thousands of gray whales swim past the coast off Mount Tamalpais in late December through January, on their way to calving grounds in Southern and Baja California. Their numbers peak in mid-January. They appear again in March, April, and May as they head northward to feeding grounds in Alaska, peaking in mid-March. Late April and early May is the best time to see mothers and calves close to shore.

About 1,400 humpback whales feed along the California Coast. Their graceful breaching and fin-thumping can be seen from Mount Tam in November through March.

The park’s Steep Ravine cabins and campground offer whale-watchers the closest look at the ocean. A little farther away, the Coast View Trail and the western portion of the Matt Davis Trail are good alternatives. Bring binoculars.

Birds
Birdwatchers can view more than 150 species of birds within or near Mount Tamalpais State Park. Red-tailed hawks, northern harriers and turkey vultures soar over the open grasslands, while pileated, acorn and hairy woodpeckers tap holes in woodland trees. The night is filled with the hoots of great horned, spotted, barn and screech owls. Look for oceanic and intertidal birds along the coast.