Page 106 - GIS for Science, Volume 3 Preview

THE SALAS Y GOMEZ AND NAZCA RIDGES
Extending more than 2,900 kilometers of seafloor off the west coast of South America, the Salas y Gómez and Nazca Ridges are two adjacent underwater mountain chains of volcanic origin. The more adjacent ridge to the South American continent, the Nazca Ridge, stretches across roughly 1,100 kilometers between the coast of Peru and the Desventuradas Islands. The Salas y Gómez Ridge spans approximately 1,600 kilometers between the Desventuradas Islands and Rapa Nui, also known as Easter Island. The Desventuradas Islands, Rapa Nui, and its close neighbor, Salas y Gómez Island, are the only places where the Salas y Gómez and Nazca Ridges rise above sea level. All of the other 110 peaks of these seamounts lie underneath the sea surface, where they create important habitats and migration corridors for many unique species.
The islands and seamounts that make up the ridges are thought to have been produced by a common geological hot spot located close to the present location of Salas y Gómez Island. Magma that first erupted here more than 27 million years ago grew to form seamounts that were carried eastward with the tectonic movement of the Nazca Plate. New seamounts formed with new eruptions, which then followed the journey of their predecessors eastward on the Nazca Plate. These seamounts provide a detailed chronological record of the geological formation of this region that tracks the movement of the Nazca Plate eastward before it gets subducted under South America. In addition to becoming older from west to east, these seamounts generally become progressively deeper moving eastward and range between just a few meters below the surface on the western portion of the ridges to more than 3,000 meters toward the northeastern end. Drowned fringing and barrier reefs are still evident on many of these deep seamounts, reminding us that these features were all near the sea surface at some point in their past.
Chalky bluffs at the White Cliffs of Dover, England.
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Peru
Located off the west coast of South America, the Salas y Gómez and Nazca Ridges3 are two underwater mountain chains that collectively stretch across 2,900 kilometers in the South Pacific. The Salas y Gómez Ridge spans 1,600 kilometers between Rapa Nui and the Desventuradas Islands, where it connects to
the Nazca Ridge, which covers another 1,100 kilometers of seafloor before meeting the coast of Peru.
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Chile