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Geography
Officially named the Archipelago de Colon after Christopher Columbus (Cristobal Colon), the Galapagos Islands are located in the eastern Pacific Ocean approximately 600 miles (1000 km) off the west coast of South America . The closest land mass is the mainland of Ecuador to the east (the country to which they belong), to the North are the Cocos Islands 432 miles (720 km) and to the South is Easter Island and San Felix Island at 920 miles (3200 km).
The Galapagos Archipelago consists of 4,897 square miles (7880 square km) of land over 28,000 square miles (45,000 square km). The largest of the islands, Isabela, measures 1,771 square miles (4,855 square km) and making 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 composed almost exclusively of basalt giving the islands their 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 in September of 1998.
Oceanography of the Galapagos
Located at the confluence of five Ocean currents, the Cold Humboldt Current from the South, the Cool Peruvian Counter Current , Cromwell Equatorial Under Current , the tropical Panama Current and South Equatorial Current , conditions in the islands depend on the prevailing current and where the island is relatively located in the current.
This mix of water temperatures and nutrient rich upwelling of Antarctic waters gives the Galapagos Islands their unique climate and diverse marine life. The islands volcanic make-up also adds to the complexity of the environment. The porous lava provides small fish the protection they would normally receive from coral reefs, which are few in these tropical waters.
Galapagos Climate
The Galapagos Islands have a sub-tropical climate with two seasons; the rainy season and the dry season. Ocean currents are largely responsible for the climate of the islands. Though located on the equator the temperatures are much milder then one would imagine due to the cold current traveling north from Antarctica .
The rainy season runs from November until June . Unlike the name suggests the weather is typically warm and sunny with daytime air temperatures between 77-87F (26-30C) . The water temperatures reach a comfortable 75º F (24º C ), and occasional tropical rainstorms can occur. February, March and April are generally considered the best months for visiting the islands. When the weather is warm, the winds are light, the sea is calm, and the birds are nesting. In the Highland areas, the temperatures will be fresher (4-5C cooler than on the coastline) and both cloudy and sunny skies will be experienced.
After April the weather becomes cooler. July to November marks the dry season. Temperatures become cooler (75-77F, 24-25C) and the skies cloudier although it seldom rains. Water temperatures drop to 70º F (21ºC) or below and the winds can make the water choppy. A sweater or jacket may be necessary on cloudy days and at night. August and September tend to be considered the "worst" months to visit when there is little sun, it can be quite cold, and the water the roughest. In the Highland areas, the "Garua" (fine mist and clouds) season is experienced regularly over high ground at this time of the year.
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