Rocas Alijos

Rocas Alijos, or Escollos Alijos (English: Alijos Rocks) are a group of tiny, steep and barren volcanic islets or above-water (as well as below-water) rocks in the Pacific Ocean at 24°57′31″N 115°44′59″W / 24.95861°N 115.74972°W. They are part of Comondú municipality of the Mexican state of Baja California Sur, and situated about 300 km west of the mainland. The total surface area is less than 1,000 square metres. The official area figure of 0.012 square kilometres (0.0046 sq mi).[1]

The group consists of three principal rocks and numerous smaller ones. South Rock, the largest of the group, is 34 meters (111 ft) high, with a diameter of only 14 meters (46 ft) (position 24°57′03″N 115°44′55″W / 24.95083°N 115.74861°W). Middle Rock is 18 meters (59 ft) high and about 10 meters (33 ft) in diameter. North Rock, 200 meters (656 ft) north of South Rock, is 22 meters (72 ft) high, with a diameter of 12 meters (39 ft). The rocks in between those are either submerged or so low that they are barely visible among the heavily breaking waves.

The rocks seem to be known since the early Spanish history of Mexico; they can be found on a map from 1598. The first description is from 1704, by pirate John Clipperton. But only in 1791 the first exact description was made by a Spanish sailor. South Rock was climbed for the first time in 1990 by an expedition (October 31 through November 7, 1990) under the leadership of Robert Schmieder, who edited a monograph about the rocks.[2]

The group is located at the transition zone between two major biologic provinces, at a latitude where the Pacific Current turns westward to form the North Pacific trans-oceanic current. The rocks are nesting sites of many seabirds.

The two other Mexican island groups in the Pacific Ocean that are not on the continental shelf are Guadalupe Island and Revillagigedo Islands.

Rocas Alijos-map
overview map with detail inset
Rocas Alijos 2
Rocas Alijos from the East (South Rock to the left)
Rocas Alijos 3
Rocas Alijos - South Rock (left) and Middle Rock


The breeding marine avifauna of Alijos Rocks currently consists of Leach's storm-petrel (a presumed breeder, probably a few pairs), red-billed tropicbird (14 birds), masked booby (100), and sooty tern (250). The magnificent frigatebird is a regular winter visitor but probably does not breed. The Laysan albatross is currently an annual visitor to Alijos Rocks during its winter breeding season, and may start to nest there in the near future.


  1. ^ [1] Archived July 11, 2007, at the Wayback Machine
  2. ^ [2] Archived May 24, 2011, at the Wayback Machine

External links


  • Robert W. Schmieder, Ed.: Rocas Alijos: Scientific Results from the Cordell Expeditions, Dordrecht; Boston: Kluwer Academic Publishers, 1996, ISBN 0-7923-4056-6 (Series: Monographiae biologicae, v. 75)
Baja California Sur

Baja California Sur (Spanish pronunciation: [ˈbaxa kaliˈfoɾnja suɾ] (listen), English: "South Lower California"), officially the Estado Libre y Soberano de Baja California Sur (English: Free and Sovereign State of South Lower California), is the second-smallest Mexican state by population and the 31st admitted state of the 31 states which, with Mexico City, make up the 32 Federal Entities of Mexico.

Before becoming a state on 8 October 1974, the area was known as the El Territorio Sur de Baja California ("South Territory of Lower California"). It has an area of 73,909 km2 (28,536 sq mi), or 3.57% of the land mass of Mexico, and occupies the southern half of the Baja California Peninsula, south of the 28th parallel, plus the uninhabited Rocas Alijos in the Pacific Ocean. It is bordered to the north by the state of Baja California, to the west by the Pacific Ocean, and to the east by the Gulf of California, or the "Sea of Cortés". The state has maritime borders with Sonora and Sinaloa to the east, across the Gulf of California.

The state is home to the tourist resorts of Cabo San Lucas and San José del Cabo. Its largest city and capital is La Paz.

Borojevia paracerebrum

Borojevia paracerebrum is a species of calcareous sponge from Mexico. The species is named after its similarity to Borojevia cerebrum.

Comondú Municipality

Comondú is a municipality of the Mexican state of Baja California Sur. It had a population of 70,816 inhabitants in 2010 census (INEGI). With a land area of 16,858.3 km² (6,509.03 sq mi), it is the seventh-largest municipality in area in Mexico. The municipal seat is located in Ciudad Constitución.

The Spanish missions of San José de Comondú and San Luis Gonzaga are located in this municipality. Rocas Alijos, a group of tiny rocks that are 300 km west off the coast, are part of the municipality.

Geology of the Pacific Ocean

The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth.The tectonic plates continue to move today. The slowest spreading ridge is the Gakkel Ridge on the Arctic Ocean floor, which spreads at less than 2.5 cm/year (1 in/year), while the fastest, the East Pacific Rise near Easter Island, has a spreading rate of over 15 cm/year (6 in/year).

Guadalupe Island

Guadalupe Island or Isla Guadalupe is a volcanic island 250 km² and located 241 kilometres (150 mi) off the west coast of Mexico's Baja California Peninsula and some 400 kilometres (250 mi) southwest of the city of Ensenada in the state of Baja California, in the Pacific Ocean. The two other Mexican island groups in the Pacific Ocean that are not on the continental shelf are Revillagigedo Islands and Rocas Alijos. Guadalupe Island and its islets are the westernmost region of Mexico.

List of codes used in the World Geographical Scheme for Recording Plant Distributions

The World Geographical Scheme for Recording Plant Distributions (WGSRPD) is a biogeographical system developed by the international Biodiversity Information Standards (TDWG) organization, formerly the International Working Group on Taxonomic Databases. The system provides clear definitions and codes for recording plant distributions at four scales or levels, from "botanical continents" down to parts of large countries. Current users of the system include the International Union for Conservation of Nature (IUCN), the Germplasm Resources Information Network (GRIN), and the World Checklist of Selected Plant Families (WCSP). Plants of the World Online uses Kew's data sources, and hence also uses the WGSRPD for distributions.

List of islands in the Pacific Ocean

The Pacific Islands are the islands of the Pacific Ocean. Three major groups of islands in the Pacific Ocean are Polynesia, Micronesia and Melanesia. Depending on the context, Pacific Islands may refer to countries and islands with common Austronesian origins, islands once or currently colonized or Oceania. The indigenous inhabitants of the Pacific Islands are referred to as Pacific Islanders. This is a list of many of the major Pacific islands, organized by archipelago or political unit. In order to keep this list of moderate size, links are given to more complete lists for countries with large numbers of small or uninhabited islands.

List of islands of Mexico

This is an incomplete list of islands of Mexico.

Revillagigedo Islands

The Revillagigedo Islands (Spanish: Islas Revillagigedo, IPA: [reˈβiʝa xiˈxeðo]) or Revillagigedo Archipelago are a group of four volcanic islands in the Pacific Ocean, known for their unique ecosystem. They lie approximately 390 kilometres (240 mi) southwest of Cabo San Lucas, the southern tip of the Baja California Peninsula, and 720 to 970 kilometres (450 to 600 mi) west of Manzanillo. They are located around 18°49′N 112°46′W. Technically part of the Mexican state of Colima, the islands are under Mexican federal jurisdiction.

In July 2016, the Revillagigedo Archipelago were inscribed as a UNESCO World Heritage Site, and in November 2017 they were declared to be a marine reserve and a national park of Mexico.

Robert Schmieder

Robert William Schmieder (born July 10, 1941) is an American scientist and explorer. Schmieder has had a multidisciplinary career, broadly divided between physics and related physical sciences, and natural science and exploration. In most of his projects, he created and led teams of both professional scientists and volunteers. His work is documented in about 100 technical publications and 10 books. Among his most significant work was the invention of laser spark spectroscopy (now commercialized), the formulation of nanologic (the use of nanoscale devices in computers), and the concept of underwater islands (which led to designation of the Cordell Bank National Marine Sanctuary).

Sea urchins of the Gulf of California

The sea urchins of the Gulf of California live between the coasts of the Baja California Peninsula to the west and mainland state of Sonora, Mexico to the east. The northern boundary is the lateral band of land with the remains of the Colorado River Delta, and the southern is the Pacific Ocean.

The Gulf of California is known for its high diversity and endemism of biota. One type of marine animal that can be found in this region is the sea urchin (class echinoidea, in the phylum echinodermata). One echinoid, Mellita granti, is a sea urchin endemic to the Gulf of California.

Costa Rica

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