Galápagos Islands
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 | |
| Geography | |
|---|---|
| Location | Pacific Ocean |
| Coordinates | 0°30′S 90°30′W / 0.500°S 90.500°W |
| Total islands | 127 |
| Major islands | 18 |
| Area | 8,010[a] km2 (3,090 sq mi)[1] |
| Highest elevation | 1,707 m (5600 ft) |
| Highest point | Volcán Wolf |
| Administration | |
| Province | Galápagos |
| Capital city | Puerto Baquerizo Moreno |
| Demographics | |
| Population | 33,042 (2020) |
| Pop. density | 3/km2 (8/sq mi) |
| Additional information | |
| Time zone | |
Official name | Galápagos Islands |
| Type | Natural |
| Criteria | vii, viii, ix, x |
| Designated | 1978 (2nd session) |
| Reference no. | 1 |
Region | South America |
Extension | 2001 and 2003 |
Endangered | 2007–2010 |
.svg)
The Galápagos Islands[b] (Spanish: Islas Galápagos) are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, 485 nautical miles (898 km; 558 mi) 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.[3] José de Villamil, the founder of the Ecuadorian Navy, led the push to colonize and settle the islands,[3] 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
[edit]The Galápagos Islands take their name from their native giant tortoises, known in Spanish as "galápagos" (derived from a pre-Roman Iberian word meaning 'turtle' or 'tortoise').[4][5] The name is first attested as the Spanish/Latin hybrid Insulae de los Galopegos ('Islands of the Turtles') on the map of the Americas in Abraham Ortelius's Theater of the Lands of the World (Latin: Theatrum Orbis Terrarum), first published in 1570.[6] Early sailors to the islands also dubbed them the "Enchanted Isles" due to the difficulty in navigating the winds and currents around them.[7]
The islands have also been known by other names. They were officially named the Ecuador Archipelago (Archipiélago de Ecuador) or Archipelago of the Equator (Archipiélago del Ecuador) following their annexation by Ecuador in 1832.[8] In 1892, upon the quadricentennial of Christopher Columbus's first voyage they were renamed the Colón or Columbus Archipelago (Archipiélago del Colón).[8] This remains their official title in Ecuadorian maps and state documents.[6]
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.[8] 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.[9]
Geology
[edit]
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 2.5 inches (6.4 cm) per year.[10] 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.[11]
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) 200 km (120 mi) 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.[12][13][14]
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 240 cm (94 in) uplift between 1992 and 1998, most recent eruption in 2005, while Fernandina on Fernandina Island indicated an uplift of 90 cm (35 in), 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.[15]
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 2 km (1.2 mi) 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.[15][16][17][14] 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.[18]
Physical geography
[edit]
The Galápagos Islands have a land area of about 8,000 square kilometers (3,100 sq mi) spread over 45,000 square kilometers (17,000 sq mi) of ocean.[19] The archipelago is composed of 127 islands, islets, and rocks, of which 19 are large islands with an area exceeding 1 square kilometer (0.39 sq mi).[20][21] The largest island by far is Isabela. Its area of 4,588 square kilometers (1,771 sq mi) makes up close to three-fifths of the Galápagos's total area. The islands of Santa Cruz (986 square kilometers (381 sq mi)) and Fernandina (642 square kilometers (248 sq mi)) follow.[22] The highest point in the islands is Volcán Wolf on Isabela, reaching an altitude of 1,700 meters (5,600 ft). 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.[23]
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 1,000 km (620 mi) to the west of mainland Ecuador, the country to which they belong.[19] 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 220 km (140 mi).[22] Although bisected by the equator, the archipelago is considered to be wholly within the South Pacific Ocean by the International Hydrographic Organization.[24] The surrounding Galápagos Marine Reserve encompasses 133,000 square kilometers (51,000 sq mi) of ocean within 40 nautical miles of the archipelago.[20] 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.[25]
Main islands
[edit]
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There are 19 islands with areas above 1 square kilometer (0.39 sq mi).
| Island | English Name | Area | Highest Point | Notable Features |
|---|---|---|---|---|
| Isabela | Albemarle | 4,588 square kilometers (1,771 sq mi) | 1,707 meters (5,600 ft) | Six prominent shield volcanoes, five active, as well as extensive lava fields.[26] |
| Santa Cruz | Indefatigable | 986 square kilometers (381 sq mi) | 864 meters (2,835 ft) | Located in the center of the archipelago, with about twenty inactive smaller volcanic cones.[27] |
| Fernandina | Narborough | 642 square kilometers (248 sq mi) | 1,494 meters (4,902 ft) | The youngest and westernmost of the islands, with active volcano that erupts periodically.[28] |
| Santiago | James | 585 square kilometers (226 sq mi) | 907 meters (2,976 ft) | Dominated by Cerro Cowan, it contains extensive lava flows.[29] |
| San Cristóbal | Chatham | 547 square kilometers (211 sq mi) | 896 meters (2,940 ft) | The most eastern island, made up of two inactive volcanoes.[30] |
| Floreana | Charles | 173 square kilometers (67 sq mi) | 640 meters (2,100 ft) | Most southern of the main islands, with one of the only sources of fresh water: a large scenic lagoon.[31] |
| Marchena | Bindloe | 130 square kilometers (50 sq mi) | 343 meters (1,125 ft) | Relatively remote, located well to the north of Santiago.[32] |
| Española | Hood | 60 square kilometers (23 sq mi) | 206 meters (676 ft) | The oldest of the islands, with dramatic cliffs lining its southern coast.[33] |
| Pinta | Abingdon | 60 square kilometers (23 sq mi) | 850 meters (2,790 ft) | In the north of the archipelago, with sharp, steep cliffs up to 300 meters (980 ft) in height. [34] |
| Baltra | South Seymour | 27 square kilometers (10 sq mi) | 100 meters (330 ft) | The airstrip occupies a good part of the flat island.[35] |
| Santa Fe | Barrington | 24 square kilometers (9.3 sq mi) | 259 meters (850 ft) | Old island with lavas dating back more than 3 million years. It is located to the southeast of Santa Cruz.[36] |
| Pinzón | Duncan | 18 square kilometers (6.9 sq mi) | 458 meters (1,503 ft) | A mostly arid island located directly west of Santa Cruz.[34] |
| Genovesa | Tower | 14 square kilometers (5.4 sq mi) | 76 meters (249 ft) | Located north of the main islands, between Santa Cruz and San Cristóbal. [37] |
| Rábida | Jervis | 4.9 square kilometers (1.9 sq mi) | 367 meters (1,204 ft) | Small island in the geographic center of the archipelago, with reddish sand beaches.[38] |
| Seymour Norte | North Seymour | 1.9 square kilometers (0.73 sq mi) | 0 meters (0 ft) | Small, flat island.[38] |
| Wolf | Wenman | 1.3 square kilometers (0.50 sq mi) | 253 meters (830 ft) | Located about 160 kilometers (99 mi) from the other islands. It is the top of a very large volcano based in the ocean bottom.[39] |
| Tortuga | — | 1.3 square kilometers (0.50 sq mi) | — | [40] |
| Bartolomé | Bartholemew | 1.2 square kilometers (0.46 sq mi) | 114 meters (374 ft) | Made of tuff cones and spatter cones, including Pinnacle Rock, an immense tuff cone.[41] |
| Darwin | Culpepper | 1.1 square kilometers (0.42 sq mi) | 165 meters (541 ft) | Wolf's twin island, also the peak of a large oceanic volcano.[39] |
Minor islands
[edit]
- 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.
- South Plaza Island (Isla Plaza Sur) – It is named in honor of a former president of Ecuador, General Leónidas Plaza. It has an area of 0.13 km2 (0.050 sq mi) and a maximum altitude of 23 m (75 ft). The flora of South Plaza includes Opuntia cactus and Sesuvium plants, which form a reddish carpet on top of the lava formations. Iguanas (land, marine and some hybrids of both species) are abundant, and large numbers of birds can be observed from the cliffs at the southern part of the island, including tropic birds and swallow-tailed gulls.
- North Plaza Island – This island lies north of South Plaza Island.
- Nameless Island – A small islet used mostly for scuba diving.
- Roca Redonda – An islet approximately 25 km (16 mi) northwest of Isabela. Herman Melville devotes the third and fourth sketches of The Encantadas to describing this islet (which he calls "Rock Rodondo") and the view from it.
- Guy Fawkes Island – A small island of the coast of Santa Cruz. It is an island group composed of two crescent-shaped islets—North Guy Fawkes I. (I. Guy Fawkes Norte) and South Guy Fawkes I. (I. Guy Fawkes Sud)—and two rocks located northwest of Santa Cruz Island in the Galápagos Archipelago in Ecuador. The group is uninhabited but sometimes visited by scuba divers.
- Isla Beagle – This small island near to Santiago is largely uninhabited.
- Isla Caldwell – This island is near Floreana and has a length of 3.06 kilometers.
- Isla Campéon – Also known as Champion island, this islet is 1.64 kilometers in length and is one of the last refuges of the Floreana mockingbird.
- Isla Watson – One of the many islets around Floreana island.
- Enderby Island – Besides of Isla Campéon, this island is another place where the Floreana mockingbird lives.
- Gardner Island (Galapagos) – In the Galapagos Islands, there are two places called Gardner Island. There is one island near Española, and one island near Floreana.
- Mosquera Island – Mosquera is one of the smallest islands in the archipelago. Located between North Seymour and Baltra Islands, it consists of many coral reefs, making it a great site for practicing snorkel and observing the marine life.
Mosquera is also home to one of the largest colonies of sea lions in the Galapagos, and there have been occasional orca whale sightings around the islet. As is usual in the archipelago, the islet is shared by many seabirds, marine iguanas, blue-footed boobies and Sally Lightfoot crabs.
- Tortuga Island – Isla Tortuga is uniquely shaped like a crescent. The island is actually a collapsed volcano that is a nesting location for a variety of seabirds such as Frigatebirds and the elusive Red-Billed Tropicbird, among others.
- Isla Los Hermanos – A small island off Isabela.
- Isla Sombrero Chino – One of the most recognizable of the Galapagos Islands, Sombrero Chino's name means "Chinese Hat." It's easy to see why: this islet off Santiago is shaped like an old-fashioned Chinaman's hat, a gently sloping cone rising out of the clear Galapagos water. Because of its distinctive shape, Sombrero Chino has fascinated visitors as long as they have been coming to Galapagos.
- Daphne Minor – Located near, and similar to, Daphne Major, as both are tuff cones devoid of trees.
- Las Tintoreras Islet – One of a group of seven small islets to the south of the bay of Puerto Villamil in the island of Isabela, that forms part of the archipelago and national park of the Galapagos Islands, including administratively in the Province Of Galapagos.
- Leon Dormido – Island located off San Cristobal.Visually striking, the two rocks of Leon Dormindo, which means "Sleeping Lion," soar to some 450 feet (140 meters) into the air. The mild current between the two rocks creates a hotbed habitat for an extremely diverse group of fish and mammals.
- Isla Cowley – A very small island located off Isabela.
- Isla El Edén – Eden Island is a sliver of volcanic rock located along the northwest shore of the large Santa Cruz Island. Isla El Edén measures less than 2,000 square feet in diameter. Despite its small size of .01 square miles, it exhibits three distinct landscapes. One is flat, arid and barren. In the middle is a 233 foot cliff.
- Isla Albany – Albany Rock is a small crescent shaped islet located in the northwest of Santiago Island.
- Isla Onslow – One of the many islands near Floreana.
- Corona Del Diablo – Corona Del Diablo, also known as the Devil's Crown, located off Floreana Island, not far from the shore, is a ring of uneven rocks that stick out of the water. Its name comes from the fact that it looks almost like an uncomfortable crown, that only the devil could wear.
Climate
[edit]
Although the islands are located on the equator, the Humboldt Current brings cold water to them, causing frequent drizzles during most of the year. The weather is regularly influenced by the El Niño events, which occur every 3 to 7 years and bring warmer sea surface temperatures, a rise in sea level, greater wave action, and a depletion of nutrients in the water.[42] This cycle can greatly affect the precipitation from one year to another. At Charles Darwin Station, the precipitation during the month of March in the particularly wet year of 1969 was 249.0 mm (9.80 in), but during March 1970 the next year it was only 1.2 mm (0.047 in).
There is also a large range in precipitation from one place to another and across the islands' two main seasons. The archipelago is mainly characterized by a mixture of a tropical savanna climate and a semi-arid climate, transitioning to a tropical rainforest climate in the northwest. During the rainy season known as the garúa from June to November, the temperature near the sea is around 22 °C (72 °F), a steady cool wind blows from south and southeast, frequent drizzles (garúas) for days, and dense fog conceals the islands. During the warm season from December to May, the average sea and air temperatures rise to around 25 °C (77 °F), there is no wind at all, and the sun shines apart from sporadic strong downpours. Weather also changes as altitude increases on the larger islands. Temperature decreases gradually with altitude, while precipitation increases due to the condensation of moisture from clouds on the slopes. This pattern of generally wet highlands and drier lowlands affects the plant life on the larger islands. The vegetation in the highlands tends to be green and lush, with tropical woodland in places. The lowland areas tend to have arid and semi-arid vegetation, with many thorny shrubs and cacti and areas of barren volcanic rock.
Some islands also fall within the rain shadow of others during some seasons. During March 1969, the precipitation over Charles Darwin Station on the southern coast of Santa Cruz was 249.0 mm (9.80 in), while on nearby Baltra Island the precipitation during the same month was only 137.6 mm (5.42 in). This is because Baltra is located behind Santa Cruz when the prevailing winds are southerly, causing more moisture to fall on the Santa Cruz highlands.
| Climate data for San Cristóbal Island, 1981–2010 normals | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Mean daily maximum °C (°F) | 29.2 (84.6) |
30.3 (86.5) |
30.5 (86.9) |
30.2 (86.4) |
29.2 (84.6) |
27.6 (81.7) |
26.4 (79.5) |
25.6 (78.1) |
25.7 (78.3) |
26.0 (78.8) |
27.0 (80.6) |
27.8 (82.0) |
28.0 (82.3) |
| Daily mean °C (°F) | 26.1 (79.0) |
26.7 (80.1) |
26.7 (80.1) |
26.5 (79.7) |
25.9 (78.6) |
24.7 (76.5) |
23.5 (74.3) |
22.7 (72.9) |
22.8 (73.0) |
23.0 (73.4) |
23.9 (75.0) |
24.8 (76.6) |
24.8 (76.6) |
| Mean daily minimum °C (°F) | 22.9 (73.2) |
23.1 (73.6) |
22.9 (73.2) |
22.8 (73.0) |
22.7 (72.9) |
21.7 (71.1) |
20.7 (69.3) |
19.8 (67.6) |
19.8 (67.6) |
20.0 (68.0) |
20.9 (69.6) |
21.7 (71.1) |
21.6 (70.9) |
| Average precipitation mm (inches) | 83.4 (3.28) |
107.4 (4.23) |
106.3 (4.19) |
94.9 (3.74) |
41.9 (1.65) |
32.5 (1.28) |
18.8 (0.74) |
9.8 (0.39) |
7.6 (0.30) |
11.0 (0.43) |
12.6 (0.50) |
51.5 (2.03) |
577.7 (22.76) |
| Average precipitation days | 11 | 10 | 11 | 6 | 5 | 8 | 13 | 14 | 12 | 11 | 8 | 10 | 119 |
| Source: World Meteorological Organization[43] | |||||||||||||
The following table for the especially wet year of 1969 shows the variation of precipitation in different places of Santa Cruz Island:
| Location | Charles Darwin Station |
Devine Farm | Media Luna |
|---|---|---|---|
| Altitude | 6 m | 320 m | 620 m |
| January | 23.0 mm | 78.0 mm | 172.6 mm |
| February | 16.8 mm | 155.2 mm | 117.0 mm |
| March | 249.0 mm | 920.8 mm | 666.7 mm |
| April | 68.5 mm | 79.5 mm | 166.4 mm |
| May | 31.4 mm | 214.6 mm | 309.8 mm |
| June | 16.8 mm | 147.3 mm | 271.8 mm |
| July | 12.0 mm | 42.2 mm | 135.6 mm |
| August | 3.8 mm | 13.7 mm | 89.5 mm |
| September | 18.5 mm | 90.9 mm | 282.6 mm |
| October | 3.2 mm | 22.6 mm | 96.5 mm |
| November | 11.0 mm | 52.8 mm | 172.7 mm |
| December | 15.7 mm | 84.1 mm | 175.3 mm |
| TOTALS | 469.7 mm | 1901.7 mm | 2656.4 mm |
Ecology
[edit].jpg)
Terrestrial
[edit]Most of the Galápagos is covered in semi-desert vegetation, including shrublands, grasslands, and dry forest. A few of the islands have high-elevation areas with cooler temperatures and higher rainfall, which are home to humid-climate forests and shrublands, and montane grasslands (pampas) at the highest elevations. There are about 500 species of native vascular plants on the islands, including 90 species of ferns. About 180 vascular plant species are endemic.[44]
The islands are well known for their distinctive endemic species, including giant tortoises, finches, flightless cormorants, Galápagos lava lizards and marine iguanas, which evolved to adapt to islands' environments.[44]
History
[edit]Pre-Columbian era
[edit]Whether Polynesians or the indigenous peoples of South America ever made it to the islands is disputed. Oceanic Pacific islands in the same general area as Galápagos—including Clipperton, Cocos, the Desventuradas, the Juan Fernández Islands, and the Revillagigedos—were all uninhabited when discovered by Europeans, with no evidence to indicate any prehistoric human activity.[45][46][47] The easternmost oceanic island in the South Pacific that was discovered with a human population was Easter Island,[46] whose Rapa Nui people are known to be Polynesian rather than South American.[48]
In 1572, the Spanish chronicler Pedro Sarmiento de Gamboa claimed that Topa Inca Yupanqui, the second Sapa Inca of the Inca Empire, had visited the archipelago. There is, however, little evidence for this and many experts consider it a far-fetched legend, especially since the Incas were not typically a seafaring people.[49] A 1952 archaeological survey by Thor Heyerdahl and Arne Skjølsvold found potsherds and other artifacts from several sites on the islands that they claimed suggested visitation by South Americans during the