Muir Woods National Monument

Less than 20 kilometers (12 miles) north of the Golden Gate is this famed stand of virgin redwoods, Sequoia sempervirens. Though not among the largest of the redwoods, some of the trees in the Monument reach a height of 73 meters (240 feet). They occupy the floor and lower slopes of a rather steep-sided canyon on the southern flank of Mount Tamalpais. Other trees found in association with them here include California bay, Umbellularia californica, and tanbark oak, Lithocarpus densiflorus; however, in this virgin forest they are not as conspicuous an element as they are in the second-growth forests.

The thick understory includes Western azalea, Rhododendron occidentale, huckleberry, Vaccinium ovatum, redwood sorrel, Oxalis oregana, redwood violet, Viola sempervirens, and ginger, Asarum caudatum. In the drier areas on the slopes the sword fern, Polystichum munitum, grows, while along the streambanks the lady fern, Athyrium filix-femina, is common. The type locality of the rare Arctostaphylos virgata, found only in Marin County, is on the upper slopes.

There is a varied and abundant fauna. Both silver salmon, Oncorhynchus kisutch, and steelhead, Salmo gairdnerii gairdnerii, spawn in the creek.

The redwoods here, as elsewhere in Marin County, are on soils derived from the Franciscan formation which dates to the Jurassic. They are not found on the Cenozoic soils in the northern portion of the County.

Integrity: There has not been a significant fire since 1845 and the area has been protected since 1908. There are 10 kilometers (6 miles) of trails and some buildings near the entry. Careful management is required to protect the trees and soils.

Use: Educational, observational, research, light recreation.

Ref: Smith, G. L. 1963. Flowers and Ferns of Muir Woods, Muir Woods Natural Hist. Assn.

April 1976