The Marin Hills are a series of steep high ridges and peaks in southern

Marin County Marin County is a county located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2020 census, the population was 262,231. Its county seat and largest city is San Rafael. Marin County is acros ...

. They are a part of the long

Pacific Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although the ...

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher ...

system. The centerpoint of these hills is the 2,571 foot (784 m)

Mount Tamalpais Mount Tamalpais (; ; Miwok: ''Támal Pájiṣ''), known locally as Mount Tam, is a peak in Marin County, California, United States, often considered symbolic of Marin County. Much of Mount Tamalpais is protected within public lands such as Mou ...

near Mill Valley. The hills are bordered to the north by the

Santa Rosa Plain Santa Rosa ( Spanish for " Saint Rose") is a city and the county seat of Sonoma County, in the North Bay region of the Bay Area in California. Its estimated 2019 population was 178,127. It is the largest city in California's Wine Country and ...

and

Laguna de Santa Rosa The Laguna de Santa Rosa is a wetland complex that drains a watershed encompassing most of the Santa Rosa Plain in Sonoma County, California, United States. The California Office of Environmental Health Hazard Assessment has issued a safe eati ...

; to the east by

San Pablo Bay San Pablo Bay is a tidal estuary that forms the northern extension of San Francisco Bay in the East Bay and North Bay regions of the San Francisco Bay Area in northern California. Most of the Bay is shallow; however, there is a deep wate ...

, the northern arm of

San Francisco Bay San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water f ...

; to the south by

Golden Gate Strait The Golden Gate is a strait on the west coast of North America that connects San Francisco Bay to the Pacific Ocean. It is defined by the headlands of the San Francisco Peninsula and the Marin Peninsula, and, since 1937, has been spanned by t ...

; and to the west by the

San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal) ...

, running through

Tomales Bay Tomales Bay is a long, narrow inlet of the Pacific Ocean in Marin County in northern California in the United States. It is approximately long and averages nearly wide, effectively separating the Point Reyes Peninsula from the mainland of Mar ...

Olema Valley Olema Valley is a gorge formed by the San Andreas Fault in rural west Marin County, Northern California. The valley runs from the southern end of Tomales Bay through Point Reyes Station, the town of Olema, and Dogtown, to the Bolinas Lagoon, wh ...

Bolinas Lagoon Bolinas Lagoon is a tidal estuary, approximately in area, located in the West Marin region of Marin County, California, United States, adjacent to the town of Bolinas. It is a part of the Greater Farallones National Marine Sanctuary. In 1974, ...

, and

Stinson Beach Stinson Beach is an unincorporated community and census-designated place (CDP) in Marin County, California, on the west coast of the United States. Stinson Beach is located east-southeast of Bolinas, at an elevation of . The population of the St ...

. Parts of the hills are protected for their scenic beauty by

Mount Tamalpais State Park Mount Tamalpais State Park is a California state park, located in Marin County, California. The primary feature of the park is the Mount Tamalpais. The park contains mostly redwood and oak forests. The mountain itself covers around . There ar ...

and the

Golden Gate National Recreation Area The Golden Gate National Recreation Area (GGNRA) is a U.S. National Recreation Area protecting of ecologically and historically significant landscapes surrounding the San Francisco Bay Area. Much of the park is land formerly used by the United ...

. The many ridges and peaks of these hills form a dramatic backdrop to the

Golden Gate Bridge The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the strait connecting San Francisco Bay and the Pacific Ocean. The structure links the U.S. city of San Francisco, California—the northern tip of the San Francisco Pen ...

, the

San Francisco San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17t ...

skyline, and several towns around

Richardson Bay Richardson Bay (originally Richardson's Bay) is a shallow, ecologically rich arm of San Francisco Bay, managed under a Joint Powers Agency of four northern California cities. The Richardson Bay Sanctuary was acquired in the early 1960s by the ...

when viewed from the south.

Climate

Since these hills lie near the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...

, they force much of the incoming moisture out of the air and rainfall here is much greater than the bayside of Marin County. Due to this

orographic rain In meteorology, the different types of precipitation often include the character, formation, or phase of the precipitation which is falling to ground level. There are three distinct ways that precipitation can occur. Convective precipitation is g ...

effect, the

Marin Municipal Water District The Marin Municipal Water District (or MMWD) is the government agency that provides drinking water to southern and central Marin County, California. Chartered in 1912, it became California's first municipal water district. It serves 191,000 custom ...

has constructed several dams and

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contr ...

s to store water for the population of Marin. The high rainfall also makes these hills conducive for

Coast redwood ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995:606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal ...

and

Douglas-fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...

. However, a side effect is that the eastern hills, where most of Marin's population lives, are drier and hotter due to the shielding of marine breezes. The low hills to the east support only

California oak woodland California oak woodland is a plant community found throughout the California chaparral and woodlands ecoregion of California in the United States and northwestern Baja California in Mexico. Oak woodland is widespread at lower elevations in coastal ...

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranea ...

and

grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...

Landscape

The western part of the hills once had extensive

old growth An old-growth forestalso termed primary forest, virgin forest, late seral forest, primeval forest, or first-growth forestis a forest that has attained great age without significant disturbance, and thereby exhibits unique ecological featur ...

forests, but in the 1800s they were a source of timber for the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area G ...

, and thus logging took out most of the old growth stands; however, one old growth stand remained uncut in Sequoia Canyon, due to the steep terrain and it therefore withstood pressure from loggers and water companies. This stand is now the

Muir Woods National Monument Muir Woods National Monument is a United States National Monument managed by the National Park Service, named after naturalist John Muir. It is located on Mount Tamalpais near the Pacific coast, in southwestern Marin County, California. It is ...

, part of the

. The parklands of these hills are popular with tourists and locals alike seeking to escape the urban areas of the

Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Gov ...

Fauna

The

Black-tailed Deer Two forms of black-tailed deer or blacktail deer that occupy coastal woodlands in the Pacific Northwest of North America are subspecies of the mule deer (''Odocoileus hemionus''). They have sometimes been treated as a species, but virtually all r ...

is the most common large

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...

of the Marin Hills.California Department of Fish and Game, "Deer Distribution in California" (map)
, accessed April 3, 2007

References

{{Reflist Mountain ranges of Marin County, California California Coast Ranges California placenames of Native American origin Mount Tamalpais Mountain ranges of the San Francisco Bay Area Mountain ranges of Northern California