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Galapagos Geology, History, Climate, annd Oceanography
Geology
- Galapagos product of a mantle plume, columns of hot rock rising
from Earth's core.
- Galapagos Platform = shallow region of ocean on which islands
sit; due to mantle plumes pushing up on lithosphere.
- Galapagos Spreading Center = mid-ocean ridge north of Galapagos;
location of transform fault.
- Chain of volcanoes produced by lithospheric movement over plume. Galapagos
located beneath Nasca Plate, moving east-southeast. Lithosphere
movement carries volcano away from plume, so volcano becomes extinct, and
as it cools, it sinks below sea level. Such event has happened to
ancient Galapagos islands.
- Islands at least 8 million years old. Mantle plume at least 90
million years old.
- 2 types of volcanos: large, inverted soup bowl (Isabela and Fernandina)
and small, shield volcanos (east); difference from lithospheric thickness.
Caldera form flat top of volcano, due to collapse (Marchena,
Genovesa: Darwin Bay).
- Historic eruptions on Pinta, Marchena, and Genovesa.
History
- 1535 (time of Spanish conquest)-Galapagos accidentally discovered
by Fray Tomás de Berlanga, Panama; called land worthless, found little
fresh water. (Water eventually found by following tortoises to highlands.)
- Late 16th c.-base for English pirates whose main target was Spanish
ships; fresh water from Buccaneer Cove, NW Santiago, meat from tortoises.
- 1790-Whalers replace pirates; dozens of ships/yr, hunt tortoises,
some races to extinction. Fur seals also targeted, 20th c. almost extinct
but since recovered.
- 1807-First permanent human inhabitant, Patrick Watkins, Floreana.
- 1813 (war between US, Britain, France)-American captain David Porter
releases goats near James Bay, devestate flora, threaten tortoise habitat.
- 1832-2 yr. old Republic of Ecuador claims Galapagos (originally
owned by Spain).
- 1833-Jose Villamil establishes first colony (Floreana), successful
but abandoned b/c of prison colonies. No coal, guano; salt mined from
near James Bay.
- 1846-no tortoises on Floreana, instead cattle, wild dogs.
- 1854-Herman Melville publishes "Los Encantadas," set in Galapagos.
- 1860's-Whaling decreases as petroleum replaces sperm oil.
- 1869-Progresso colony estab. on San Cristobal. (San Cristobal
seat of gov't today).
- 1892-Islands named "Archipelago de Colon" (present official name).
- 1893-Colonies on Isabela and Sierra Negra mine sulfur and coral (lime),
also fishing, cattle ranching.
- 19th c.-Santa Fe and Rabida tortoises extinct.
- 1924-"Galapagos: World's End" by William Beebe published, sparking
interest, beginning eco-tourism.
- 1935-Darwin's visit, noticed tortoises already disappearing
and 200-300 human inhabitants. Ecuadorian gov't decrees parts of
islands wildlife preserves (by this time, 3/14 races tortoises extinct
and Pinta race: 1 individual left, rice rat extinct on some islands, introduced
plants, goats, pigs, burros, cattle, rats, cats, dogs threaten flora and
eat bird and reptile eggs/young); nothing done to enforce decree. WWII-US
Navy build bases in Galapagos to guard Panama Canal (Baltra and Isabela);
given to Ecuadorian gov't to be airport (airports built on San Cristobal and
Isabela).
- 1959-Charles Darwin Foundation incorporated in Belgium; Galapagos
declared National Park.
- 1964-Charles Darwin Research Station.
- 1965-CDRS program of collecting tortoise eggs, raising then releasing
them (save Espanola tortoise); also for land iguanas.
- 1968-Boundaries of park (inc. 95% island) and park service estab;
goats partially eradicated.
- 1970-Organized tourism begins; 1000 visitors.
- 1990's-60,000 visitors/yr.
- Current problems: Human pop. increasing rapidly (Galapagueños),
exploiting resources (sea cucumber around Fernandina). Dogs, cats,
rats threaten iguanas and seabirds. Tens of thousands goats on Santiago,
Pinta, Isabela. Isabela goats: migrated to Volcan Alcedo, home largest
tortoise pop. Goats also sighted on Volcan Darwin, Volcan Wolf.
Climate &Oceanography
- Dry and moderate, low hanging clouds. 85 F +. Low temp
due to cool Peru/Humbolt Current and upwelling.
Reference
Notes compiled 10/11/04