Morro Rock, Morro Bay, CA, with Sandspit and Grassy Island

Morro Rock ( Salinan: ''Le'samo; '' Chumash: ''Lisamu'''; Spanish: ''El Morro'') is a volcanic plug in Morro Bay, California, on the

Pacific Coast Pacific coast may be used to reference any coastline that borders the Pacific Ocean. Geography Americas Countries on the western side of the Americas have a Pacific coast as their western or southwestern border, except for Panama, where the Pac ...

at the entrance to Morro Bay harbor. A

causeway A causeway is a track, road or railway on the upper point of an embankment across "a low, or wet place, or piece of water". It can be constructed of earth, masonry, wood, or concrete. One of the earliest known wooden causeways is the Sweet Tra ...

connects it with the shore, making it a tied island. The rock is protected as the Morro Rock State Preserve.

Geology

The Morro Rock is one of 13 volcanic plugs (remnant necks of extinct volcanoes), lava domes, and sheetlike intrusions between Morro Bay on the north and Islay Hill on the south, all in San Luis Obispo County. It is composed mostly of dacite, an igneous, volcanic rock, and partially of petrified bird

feces Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...

, which have compacted into the plug over the years. It is a groundmass of plagioclase, with

amphibole Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is A ...

(hornblende),

biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more alumino ...

pyroxene The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) ...

(augite), quartz, and glass; phenocrysts of plagioclase. Its

silica dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

(SiO2) content can range from 63 to 69 percent. The dacite volcanic plugs, lava domes, intrusive sheets, and felsitic

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

-dacite between Morro Rock and Islay Hill are part of the Morro Rock-Islay Hill Complex of the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

epoch (from 27 to 23 million years ago). The complex lies east of the San Gregorio-San Simeon-Hosgri fault (the SG-SS-H fault). This complex is one of three probable sources of the volcanic clasts within the sandstone and

conglomerate Conglomerate or conglomeration may refer to: * Conglomerate (company) * Conglomerate (geology) * Conglomerate (mathematics) In popular culture: * The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes ** Co ...

of the Miguelito and Edna members of the Pismo Formation in the Point Sur area 145–160 km (90-100 mi) to the north and west of the SG-SS-H fault. Based on paleomagnetic signatures, the Morro Rock-Islay Hill Complex was rotated 40 to 50 degrees, perhaps during late Miocene or early Pliocene time.

History

Tribal

The Salinan and Chumash tribes consider Morro Rock to be a sacred site. The Salinan name for Morro Rock is ''Le'samo'' and the Chumash name is ''Lisamu''. The Chumash had an important nearby prehistoric settlement at least as early as the Millingstone Horizon (6500-2000 B.C.E.), and the village was near the mouth of Morro Creek, at the current site of Morro Bay High School. The right of the Salinan people to climb Morro Rock for their biannual solstice ceremonies has been established, in which they celebrate the time in legend when a hawk and a raven destroyed a two-headed serpent-monster Taliyekatapelta as he wrapped his body around the base of the rock. The established Salinan right to climb the rock has been in legal dispute by the local Chumash tribe, which claims that Morro Rock is Chumash, not Salinan, territory. The Chumash also believe that the rock is so sacred that it should never be climbed. Because of its fragility, it is illegal for the general public to climb it.

European sighting

Morro Rock was probably seen by Spanish maritime explorers as early as 1542 under

Juan Rodríguez Cabrillo Juan Rodríguez Cabrillo ( pt, João Rodrigues Cabrilho; c. 1499 – January 3, 1543) was an Iberian maritime explorer best known for investigations of the West Coast of North America, undertaken on behalf of the Spanish Empire. He was the firs ...

, but its current name was given during the first European land exploration of

Alta California Alta California ('Upper California'), also known as ('New California') among other names, was a province of New Spain, formally established in 1804. Along with the Baja California peninsula, it had previously comprised the province of , but ...

. The Spanish Portolá expedition came down Los Osos Valley and camped near today's Morro Bay on September 8, 1769. Franciscan missionary and expedition member Juan Crespí noted in his diary that "we saw a great rock in the form of a round morro".

Quarry and historical landmark

The rock, which was quarried on and off from 1889 to 1969, provided material for the breakwater of Morro Bay and the improvements at Port San Luis Harbor. In 1966, a state law was adopted that transferred title to the State of California. In February 1968, the San Luis Obispo County Historical Society and the City of Morro Bay succeeded in having Morro Rock declared California Historical Landmark number 821.

Flora and fauna

Several types of birds nest on Morro Rock, including three

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the IOC adopted a consensus taxonomy of seven ge ...

species and two gull species.Joan Easton Lentz and Don DesJardin (2006) ''Introduction to Birds of the Southern California Coast'', University of California Press, 316 pages It presently serves as a reserve for

peregrine falcons The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a cosmopolitan bird of prey (raptor) in the family Falconidae. A large, crow-sized falcon, it has a blue-grey back, ...

, which are locally endangered and cause most of the laws that prohibit intervention with avian life. Sea lions and

sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the weasel family, but among the small ...

s can be seen regularly in the water around the rock. Seals, however, are much more common in the nearby Morro Bay State Park, where they breed. Other fauna include a wide selection of tide pool animals, like hermit crabs, small fish,

starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...

sea cucumber Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuria ...

mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusks, coral, and more. On land few flora can survive the harsh, dry environment on the rock, but in the surrounding bay, kelp, sea grass, kelp forest plants, and tide pool plants can survive, and a few common grasses,

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

es,

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.weeds from the mainland take root on the rock itself.

Marine protected areas

Morro Bay State Marine Recreational Management Area and Morro Bay State Marine Reserve are protected areas offshore from Morro Bay. Like underwater parks, areas help conserve ocean wildlife and marine ecosystems.

Popular culture

* It was one of many local landmarks to be mentioned in

"Weird Al" Yankovic Alfred Matthew "Weird Al" Yankovic ( ; born October 23, 1959) is an American singer, musician, songwriter, record producer, actor and author. He is best known for creating comedy songs that make light of pop culture and often parody specifi ...

's 1978 song "Take Me Down." * In the 2020 video game '' Cyberpunk 2077'', a radio station is featured called ''107.3 Morro Rock Radio'' that is named after the Morro Rock. Further, the setting of ''Cyberpunk 2077'' takes place in the fictional Night City which is built on top of Morro City. Morro Rock Reflecting in a Lagoon

References

thumb The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb ...

External links

*
City of Morro Bay

{{authority control Nine Sisters . Rock formations of California California State Reserves Volcanic plugs of California Protected areas of San Luis Obispo County, California Landforms of San Luis Obispo County, California Islands of California