[9] Mount Tamalpais is the highest peak in the Marin Hills, which are part of the Northern California Coast Ranges.

In 2004, a team of Penn State geoscientists suggested that a blind thrust fault, like the one that caused the infamous Northridge earthquake, lies beneath Mount Tamalpais.

If a blind thrust fault does exist under Mount Tamalpais, and if it ruptures, it could be potentially devastating to the North Bay, San Francisco, and any other nearby locale resting on unstable earth and loose fill.

[12] Major Mount Tamalpais rockforms include serpentine, particularly evident in outcroppings near the summit and on the north side.

The steep southeastern slopes of Mount Tamalpais drain to Arroyo Corte Madera del Presidio, which in turn discharges to Richardson Bay.

With its height, various faces, and proximity to the ocean and bay, the mountain contains many microclimates, ranging from cool and foggy in lower ocean-facing valleys with their redwood forests, to hot and dry on the manzanita slopes, cool and breezy at the summit, and shady on the heavily Douglas-fir-forested north slopes near Alpine Lake.

[15][16][17] The region sometimes gets hit with strong Pacific storms that may topple trees, and bring hurricane-force winds to exposed, barren areas like the Bolinas Ridge and the summit of Mount Tamalpais.

This leads to the fact that the eastern slopes contain only oak, pine, chaparral shrub, coastal sage scrub, grassland and sparse Douglas-fir forest.

Temperatures on top of Mount Tamalpais are generally somewhat cooler than places next to the San Francisco Bay or the ocean due to elevation.

In summer, however, the top of Mount Tamalpais may actually be warmer than the middle, foggy elevations due to a thermal inversion.

The summer fog and breezes make locations on Mount Tamalpais, closer to the ocean, cooler than the blazing hot interior valleys.

Plant communities on the mountain include various types of hardwood and coniferous forests, coastal scrub, chaparral, grassland, and wetland vegetation.

Mixed evergreen forests of various combinations of tanoak, madrone, coast and canyon live oak, and Douglas-fir are found in moist areas on middle to high elevations on the mountain.

Low-elevation areas below the fog line with relatively low overall rainfall or thin soils are often the site of a northern coastal scrub community characterized by coastal sage-coyote brush association, with lesser amounts of poison-oak, bush monkeyflower, California blackberry, western bracken fern, and various species of grasses and forbs.

[19] Wetland vegetation types found on Mount Tamalpais include coastal riparian forests, wet meadows, and some marsh areas.

On the upper slopes of the mountain, small groves of Sargent cypress trees up to 50 feet (15 m) tall can be found in serpentine areas.

Urbanization has invaded wildlife habitat, forcing many fauna in southern Marin County to retreat up onto Mount Tamalpais, Muir Woods, and the Bolinas Ridge.

A wide variety of avifauna, amphibians, arthropods and mammals are found on Mount Tamalpais, including a number of rare and endangered species.

[citation needed] The Coast Miwok are said to have believed that an evil witch dwelled at the top of Mount Tamalpais and therefore never set foot on the peak.

[citation needed] In late November 1944, a US Navy plane crashed into the mountain after developing engine trouble shortly after takeoff from Alameda Naval Air Station.

British philosopher Alan Watts owned a cabin on Mount Tamalpais later in his life where he ultimately died in his sleep of heart failure on November 16, 1973.

With numerous trailheads, a well-networked trail and road system, and hikes of greatly varying length and difficulty, the mountain offers a compelling range of attractions.

Mount Tam is also home to the Edgewood Botanic Garden and to the Sidney B. Cushing Amphitheatre where Broadway musical productions are performed every year by the Mountain Play Association.

Mount Tamalpais played an instrumental role in the birth of mountain biking many years ago, with pioneer frame builders such as Tom Ritchey, Gary Fisher, and Joe Breeze setting up shops in nearby towns.

[28] Broadway musicals are performed outdoors, several times each summer, in the stone open air Cushing Memorial Amphitheatre on the southern side of Mt.