The Nine Sisters or the Morros are a chain of twenty-three, although typically only nine are included, volcanic mountains and hills in western

San Luis Obispo County San Luis Obispo County (), officially the County of San Luis Obispo, is a county on the Central Coast of California. As of the 2020 census, the population was 282,424. The county seat is San Luis Obispo. Junípero Serra founded the Miss ...

Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban a ...

. They run between

Morro Bay Morro Bay (''Morro'', Spanish for "Hill") is a seaside city in San Luis Obispo County, California. Located on the Central Coast of California, the city population was 10,757 as of the 2020 census, up from 10,234 at the 2010 census. The town ...

and

San Luis Obispo San Luis Obispo (; Spanish for " St. Louis the Bishop", ; Chumash: ''tiłhini'') is a city and county seat of San Luis Obispo County, in the U.S. state of California. Located on the Central Coast of California, San Luis Obispo is roughly hal ...

Geography

The peaks were created more than 20 million years ago during the

Miocene Epoch The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

of the

Neogene Period The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...

, as

volcanic plug A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if rising volatile-charged ma ...

s of

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

which welled up and solidified inside softer rock which has since eroded away. Every plug, with the exception of just two, formed in a nearly straight line. Two of the plugs are in

Morro Bay State Park Morro Bay State Park is a state park on the Morro Bay lagoon, in western San Luis Obispo County, on the Central Coast of California. On the lagoon's northeastern and eastern edges in the park, there are saltwater and brackish marshes that supp ...

. The highest is Bishop Peak at .

Peaks

The peaks in order from Morro Bay to San Luis Obispo, including their height, a sortable table.

Features

The Nine Sisters, being less accessible to human intrusions, support a wide variety of

Coastal sage scrub Coastal sage scrub, also known as coastal scrub, CSS, or soft chaparral, is a low scrubland plant community of the California coastal sage and chaparral subecoregion, found in coastal California and northwestern coastal Baja California. It is ...

and

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 ...

s flora, and of birds and other fauna. Their volcanic origin makes them of significant

geological Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other E ...

interest. They are popular with

photographer A photographer (the Greek φῶς (''phos''), meaning "light", and γραφή (''graphê''), meaning "drawing, writing", together meaning "drawing with light") is a person who makes photographs. Duties and types of photographers As in other ...

s and rock climbers.

Panorama

References

External links

Landforms of San Luis Obispo County, California Volcanic plugs of California Morro Bay San Luis Obispo, California Volcanoes of California {{SanLuisObispoCountyCA-geo-stub