Officially named the Archipelago de Colon after Christopher Columbus (Cristobal Colon), the Galapagos Islands are located in the eastern Pacific Ocean approximately 625 miles (1000 km) off the west coast of South America . The closest land masses are the mainland of Ecuador to the east (the country to which they belong), the Cocos Islands 432 miles (720 km) to the north and Easter Island and San Felix Island at 920 miles (3200 km) to the south.
The Galapagos Archipelago consists of 4,897 square miles (7880 square km) of land spread over 28,000 square miles (45,000 square km) of ocean. The largest of the islands, Isabela, measures 1,771 square miles (4,855 square km) and makes up half of the total land area of the Galapagos. Volcan Wolf, on Isabela is the highest point with an elevation of 5,600 feet (1,707 meters) above sea level.
Geology of the Galapagos Islands
The Galapagos Islands are a series of gigantic volcanic peaks which are composed almost exclusively of basalt, thus the islands' dark gray color. They lie where the Nazca Plate passes under the South American Plate in an area of great geologic activity. Eruptions have taken place in historical times on Fernandina, Isabela, Pinta, Marchena, Santiago and Floreana. The most active volcanoes today are on Fernandina, Isabela, Pinta and Marchena, and the fumarolic activity may be seen intermittently on each of these islands.
Most of the islands have the classic cone shape of a "Shield Volcano" created from the build-up of layers of lava. These volcanoes have risen from 6500 to almost 10,000 ft (2000-3000 m) above the seabed. The other islands appear like a tilted tabletop and were created from Volcanic Plateaus. Plateaus are created when the eruption of basalt lava poured quickly from fissures rather than central vents.
A study of geology in action, the Galapagos Islands is one of the world's most active volcanic areas, with more than 50 eruptions in the past 200 years. Six of the volcanoes are still active (1 on Fernandina and 5 on Isabela). The most recent explosion was Cerro Azul on Isabela on May 31st, 2008.