The Galápagos Islands () are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of slightly over 33,000 in 2020. The province is divided into the cantons of San Cristóbal, Santa Cruz, and Isabela, the three most populated islands in the chain. The Galápagos are famous for their large number of endemic species, which were studied by Charles Darwin in the 1830s and inspired his theory of evolution by means of natural selection. All of these islands are protected as part of Ecuador's Galápagos National Park and Marine Reserve.
There is no firm evidence that Polynesians or the Indigenous peoples of South America reached the islands before their accidental discovery by Bishop Tomás de Berlanga in 1535. If some visitors did arrive, poor access to fresh water on the islands seems to have limited settlement. The Spanish Empire similarly ignored the islands, although during the Golden Age of Piracy, various pirates used the Galápagos as a base to raid Spanish shipping along the Peruvian coast. The goats and black and brown rats introduced during this period greatly damaged the existing ecosystems of several islands. British sailors were chiefly responsible for exploring and mapping the area. Darwin's voyage on HMS Beagle was part of an extensive British survey of the coasts of South America. Ecuador, which won its independence from Spain in 1822 and left Gran Colombia in 1830, formally occupied and claimed the islands on 12 February 1832 while the voyage was ongoing. José de Villamil, the founder of the Ecuadorian Navy, led the push to colonize and settle the islands,. gradually supplanting the English names of the major islands with Spanish ones. The United States built the islands' first airport as a base to protect the western approaches of the Panama Canal in the 1930s. After World War II, its facilities were transferred to Ecuador. With the growing importance of ecotourism to the local economy, the airport modernized in the 2010s, using recycled materials for any expansion and shifting entirely to renewable energy sources to handle its roughly 300,000 visitors each year.
Etymology
The Galápagos Islands take their name from their native giant tortoises, known in Spanish as "" (derived from a pre-Roman Iberian word meaning 'turtle' or 'tortoise'). The name is first attested as the Spanish/Latin hybrid ('Islands of the Turtles') on the map of the Americas in Abraham Ortelius's Theater of the Lands of the World (), first published in 1570. Early sailors to the islands also dubbed them the "Enchanted Isles" due to the difficulty in navigating the winds and currents around them.
The islands have also been known by other names. They were officially named the Ecuador Archipelago () or Archipelago of the Equator () following their annexation by Ecuador in 1832. In 1892, upon the quadricentennial of Christopher Columbus's first voyage they were renamed the Colón or Columbus Archipelago (). This remains their official title in Ecuadorian maps and state documents.
The islands were mapped by the English buccaneer Ambrose Cowley in 1684 and the British naval officer Captain James Colnett in 1793. Both men named the archipelago's islands after British monarchs, noblemen, and Royal Navy officers. Over time, the English names were gradually replaced by Spanish names after Ecuador annexed the islands in 1832, but the English names remain in use in older sources.
Geology
The Galápagos islands are located at the Galápagos triple junction. The archipelago is located on the Nazca plate (a tectonic plate), which is moving east/southeast, diving under the South American plate at a rate of about per year. It is also atop the Galápagos hotspot, a place where the Earth's crust is being melted from below by a mantle plume, creating volcanoes. The first islands formed here at least 8 million and possibly up to 90 million years ago.
Volcanism has been continuous on the Galápagos Islands for at least 20 million years, and perhaps even longer. The mantle plume beneath the eastward-moving Nazca plate (51 km/Myr) has given rise to a 3-kilometre-thick platform under the island chain and seamounts. Besides the Galápagos Archipelago, other key tectonic features in the region include the Northern Galápagos volcanic province between the archipelago and the Galápagos spreading center (GSC) to the north at the boundary of the Nazca plate and the Cocos plate. This spreading center terminates at the East Pacific Rise to the west and is bounded by the Cocos Ridge and the Carnegie Ridge to the east. Furthermore, the Galápagos Hotspot is at the northern boundary of the Pacific Large Low Shear Velocity Province while the Easter Hotspot is on the southern boundary.
The Galápagos Archipelago is characterized by numerous contemporaneous volcanoes, some with plume magma sources, others from the asthenosphere, possibly due to the young and thin oceanic crust. The GSC caused structural weaknesses in this thin lithosphere leading to eruptions forming the Galápagos Platform. Fernandina and Isabela in particular are aligned along these weaknesses. Lacking a well-defined rift zone, the islands have a high rate of inflation prior to eruption. Sierra Negra on Isabela Island experienced a uplift between 1992 and 1998, most recent eruption in 2005, while Fernandina on Fernandina Island indicated an uplift of , most recent eruption in 2009. Alcedo on Isabela Island had an uplift of greater than 90 cm, most recent eruption in 1993. While the older islands have disappeared below the sea as they moved away from the mantle plume, the youngest islands, Isabela and Fernandina, are still being formed. Additional characteristics of the Galápagos Archipelago are closer volcano spacing, smaller volcano sizes, and larger calderas. For instance, Isabela Island includes six major volcanoes, Ecuador, Wolf, Darwin, Alcedo, Sierra Negra and Cerro Azul, with most recent eruptions ranging from 1813 to 2018. The neighboring islands of Santiago and Fernandina last erupted in 1906 and 2009, respectively. Overall, the nine active volcanoes in the archipelago have erupted 24 times between 1961 and 2011. The shape of these volcanoes is tall and rounded as opposed to wide and smooth in the Hawaiian Islands. The Galápagos's shape is due to the pattern of radial and circumferential fissure, radial on the flanks, but circumferential near the caldera summits. It is the circumferential fissures which give rise to stacks of short lava flows.
The volcanoes at the west end of the archipelago are in general, taller, younger, have well-developed calderas, and are mostly composed of tholeiitic basalt, while those on the east are shorter, older, lack calderas, and have a more diverse composition. The ages of the islands, from west to east are 0.05 Ma for Fernandina, 0.65 Ma for Isabela, 1.10 Ma for Santiago, 1.7 Ma for Santa Cruz, 2.90 Ma for Santa Fe, and 3.2 Ma for San Cristobal. The calderas on Sierra Negra and Alcedo have active fault systems. The Sierra Negra fault is associated with a sill below the caldera. The caldera on Fernandina experienced the largest basaltic volcano collapse in history, with the 1968 phreatomagmatic eruption. Fernandina has also been the most active volcano since 1790, with recent eruptions in 1991, 1995, 2005, and 2009, and the entire surface has been covered in numerous flows since 4.3 Ka. The western volcanoes have numerous tuff cones. In late June 2018, Sierra Negra, one of five volcanoes on Isabela and one of the most active in the Galapagos archipelago, began erupting for the first time since 2005. Lava flows made their way to the coastline, prompting the evacuation of about fifty nearby residents and restricting tourist access.
Physical geography
The Galápagos Islands have a land area of about spread over of ocean. The archipelago is composed of 127 islands, islets, and rocks, of which 19 are large islands with an area exceeding . The largest island by far is Isabela. Its area of makes up close to three-fifths of the Galápagos's total area. The islands of Santa Cruz () and Fernandina () follow. The highest point in the islands is Volcán Wolf on Isabela, reaching an altitude of . While broad shield volcanoes are found in the western islands of Isabela and Fernandina, smaller, more significantly eroded landforms are found in the eastern islands.
The islands are found at the coordinates 1°40'N–1°36'S, 89°16'–92°01'W. They are located in the eastern Pacific Ocean, around to the west of mainland Ecuador, the country to which they belong. Straddling the equator, islands in the chain are located in both the Northern and Southern hemispheres, with Volcán Wolf and Volcán Ecuador on Isabela being directly on the equator. Española Island, the southernmost island of the archipelago, and Darwin Island, the northernmost one, are spread out over a distance of . Although bisected by the equator, the archipelago is considered to be wholly within the South Pacific Ocean by the International Hydrographic Organization. The surrounding Galápagos Marine Reserve encompasses of ocean within 40 nautical miles of the archipelago. The local marine environment is shaped by the convergence of several major ocean currents, including the cool Humboldt Current from the south, the warm Panama Current from the north, and the deep, nutrient-rich Cromwell Current upwelling from the west.
Main islands
There are 19 islands with areas above .
Island English Name Area HighestPoint Notable Features Isabela Albemarle Six prominent shield volcanoes, five active, as well as extensive lava fields. Santa Cruz Indefatigable Located in the center of the archipelago, with about twenty inactive smaller volcanic cones. Fernandina Narborough The youngest and westernmost of the islands, with active volcano that erupts periodically. Santiago James Dominated by Cerro Cowan, it contains extensive lava flows. San Cristóbal Chatham The most eastern island, made up of two inactive volcanoes. Floreana Charles Most southern of the main islands, with one of the only sources of fresh water: a large scenic lagoon. Marchena Bindloe Relatively remote, located well to the north of Santiago. Española Hood The oldest of the islands, with dramatic cliffs lining its southern coast. Pinta Abingdon In the north of the archipelago, with sharp, steep cliffs up to in height. Baltra South Seymour The airstrip occupies a good part of the flat island. Santa Fe Barrington Old island with lavas dating back more than 3 million years. It is located to the southeast of Santa Cruz. Pinzón Duncan A mostly arid island located directly west of Santa Cruz. Genovesa Tower Located north of the main islands, between Santa Cruz and San Cristóbal. Rábida Jervis Small island in the geographic center of the archipelago, with reddish sand beaches. Seymour Norte North Seymour Small, flat island. Wolf Wenman Located about from the other islands. It is the top of a very large volcano based in the ocean bottom. Tortuga — — Bartolomé Bartholemew Made of tuff cones and spatter cones, including Pinnacle Rock, an immense tuff cone. Darwin Culpepper Wolf's twin island, also the peak of a large oceanic volcano. Minor islands
Daphne Major – A small island directly north of Santa Cruz and directly west of Baltra, this very inaccessible island appears, though unnamed, on Ambrose Cowley's 1684 chart. It is important as the location of multidecade finch population studies by Peter and Rosemary Grant.