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Sierra Negra Volcano, Isabel Island, Galapagos

Sierra Negra Volcano, Isabel Island, Galapagos

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The Galapagos Islands' natural and human history is relatively short, but it has had an outsized influence on the world at large.

Geological History

The Galapagos Islands have a unique geological history, quite distinct from that of the South American continent. Four million years ago, the Galapagos Islands did not exist, at all; there was simply empty sea where the islands now sit. It took some of the most dramatic forces of nature for the Galapagos Islands to come into existence.

The Galapagos Islands are located on the edge of the Nazca Plate. Like all of earth's tectonic plates, the Nazca Plate is slowly drifting, in this case towards the South American Plate. However, under the Nazca Plate, there is a so-called “hot spot”, in which a plume of magma, or hot, molten rock, pushes up through the crust. As the Nazca Plate moved, this hot spot punched through the plate at different locations.

Everywhere that the hot spot pushed through, an island was formed by the cooling magma reaching the surface. The oldest of the existing islands is San Cristobál, which was believed to be formed 4 million years ago, though there is evidence to suggest that there were earlier islands that have become so eroded that that they now lie below the ocean's surface. The youngest island is Fernandina, which formed just 7,000 years ago. As the Nazca Plate continues to drift, more islands will emerge from the ocean.

These new islands, after being formed, grew with successive volcanic eruptions, which deposited cooled rock to the surface. Over time, however, wind and water erosion serve to lower the islands and smooth out the peaks; this is why Fernandina is far rockier and more jagged than San Cristobál. Over the course of millions of years, all of the existing islands will be submerged beneath the water by this erosion.

The Arrival of Life to the Galápagos and Evolution

Because they are not, and never have been, connected to the mainland, the Galapagos Islands were not quickly or easily populated by flora and fauna. Plant seeds arrived from the South American mainland when they were carried by wind currents and deposited on the islands. This precluded the arrival of many flowering plants and other species with large, heavy seeds.

Birds and insects could only arrive if they were able to fly from the mainland. Again, this prevented many bird species from making the long, 975 kilometer (605 mile) journey from the mainland. Iguanas, rats and other small, land creatures could only have reached the islands by traveling on floating vegetation that set adrift from the mainland, probably as the result of flooding. Sea creatures, both fish and aquatic mammals, arrived from elsewhere in the Pacific by swimming there.

This unique history has been important for our understanding of human history. Because the Galapagos Islands were never part of the mainland, are quite remote geographically from any larger landmass, very few species could have originally made it to the islands. However, the distinctness of the species on all the islands, which due to their different ages all had unique living conditions, suggested that there must have been evolution after the arrival of the original species. Furthermore, the lack of human contact with islands for much of its existence meant that this evolution must have occurred naturally, rather than as a result of human breeding.

Human History of the Galapagos Islands

From the moment when San Cristobál was formed, four million years ago, until the middle of the sixteenth century, no human being set foot on the Galápagos Islands. Unlike most parts of South America, there was no indigenous population on the island, the distance being too great to traverse. The first person to spot the islands was actually Tomas de Berlanga, a Spanish bishop sailing from Panama to Peru. He did not stop, however, and merely saw the islands as he passed them in his ship.

For the next two centuries, most human interaction with the islands followed Berlanga's pattern. Eventually, as the wealth of the South American coast grew and gold-laden ships set forth from its ports, pirates grew attracted to the Galapagos. They used the secluded islands as safe harbor between raids of Lima and Guayaquil. Later, whalers were drawn to the islands as a rest stop on expedition in the South Pacific. In 1807, a shipwrecked sailor arrived as the island's first permanent inhabitant, and he made a tidy living by trading with passing ships.

Twenty-five years later, in 1832, the Ecuadorian government claimed the islands as the country's possession, and the United Kingdom, Spain and Peru eventually dropped their own claims on the islands. Due to the pristine condition of the environment and wildlife on the island, the islands attracted many early scientific expeditions, none more famous than Charles Darwin's exploration in 1835. His visit led to the publication of On The Origin of Species, a tome which laid out Darwin's theory of evolution.

In the following decades, settlement finally began in earnest on the islands, with parcels of land being turned over for sugar cane production and the harvesting of lichens. The islands became an important US military installation, from the construction of the Panama Canal until the end of World War II. Much of the physical infrastructure of the islands dates from this time.

To counter growing migration from the mainland to the islands and threats to islands' flora and fauna, the Ecuadorian government declared most of the islands' territory a national park in 1957. In recent years, efforts have been made to conserve the natural wonders of the islands by restricting migration from other countries and the Ecuadorian mainland, removing introduced species that threaten native species, increasing the population of endangered species through captive breeding programs, and expanding the national park to cover the waters around the islands. Through projects like the Charles Darwin Research Station, the Galapagos Islands remain an important center for scientific inquiry, and have emerged as one of the world's premier tourist destinations.