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Geography
Home » Ecuador » Galapagos Islands Overview and History » GeographyThe islands lie in the Pacific Ocean about 1,000 kilometers west from the South American coast and straddling the Equator. There are 13 large islands (including Darwin, Wolf, Pinta, Marchena, Genovesa, Fernandina, Isabela, Santiago, Baltra, Santa Cruz, San Cristobol and Floreana), 6 smaller ones and 107 islets and rocks, with a total land area of about 8,000 square kilometers. The islands cover a total area of 7,882 sq. kilometers ranging in area from 14 sq. km to 4588 sq. km.
The islands are volcanic in origin and several volcanoes in the west of the archipelago are still very active. Galapagos is a province of the Republic of Ecuador and five of the islands are inhabited. The capital is Puerto Baquerizo Moreno on San Cristobal Island, although the largest town is Puerto Ayora on Santa Cruz.
Like many oceanic islands such as Hawaii, the Azores, and Reunion, the Galapagos are thought to be the product of a mantle plume. Mantle plumes are columns of hot rock, roughly 100 km in diameter, which rise from deep within the earth. These plumes rise because they are hotter (by perhaps as much as 200 degrees centigrade) and therefore less dense than the surrounding rock. The rate of ascent is about 10 cm/year or so.
Hence, the islands are the tips of volcanic cones, some still active. Actually, the Galapagos is one of the regions with the greatest volcanic activity in the world registering 55 major eruptions as of late - the latest in Marchena in 1991 and Fernandina in 1995.
There are two types of volcanoes in the Galapagos Islands. In the west, on the islands of Isabela and Fernandina, large volcanoes with an upside-down soup bowl or deep calderas occur. In the east, smaller shield volcanoes with gentler slopes occur. The difference between these two volcanoes is the difference in lithospheric thickness. The upside-down bowl is not common, and scientists are uncertain of its origin.
The highest point of the islands is located on Isabela Island. Wolf Volcano reaches 1,707 meters high and 2,000 fathoms (1,852 meters) deep. Because of the islands' vivid history, many have two or even three names.
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