If we could rewind time, like a movie, we would see the Galápagos Islands erupt in reverse and follow them back to where they first erupted from the sea floor.

Looking at a map of the Galápagos it is impossible to tell where these islands originated. But if we date the rocks we can see their progression through time, with the youngest, or most recent, islands created at the western edge of the archipelago, such as Fernandina.

The western volcanoes are on the leading edge of what is called the Galápagoshot spot . While Earth’s plates move across the surface of the globe, magma from deep within Earth rises to the surface in certain locations, called hot spots. “Upwelling of deep mantle material brings excess heat and magma to the surface,” Mark Kurz says. “Because these upwellings are stationary, relative to the movement of oceanic plates, plate motion pushes the volcanoes over the hotspots like a conveyor belt over a candle. When directly over a hotspot a lot of magma is delivered to the surface and volcanoes form. Eventually, when the volcano is pushed far enough from the hotspot it loses its source of magma and becomes extinct.”

The best known example of ocean islands forming over a hotspot is the Hawaiian Island chain. On the largest and southern-most island of Hawaii, Kilauea volcano has been erupting continuously since 1983. Tourists can walk on Kilauea lava flows that are only days or weeks old. The Big Island of Hawaii also has the largest volcano on earth: Mauna Loa.

But on the northern islands, such as Oahu, the volcanoes haven’t erupted for millions of years. Lush vegetation covers their volcanic terrain. The Big Island volcanoes are presently active because they are closer to the leading edge of the Hawaiian hotspot. The northern islands of Oahu and Kaui do not have active volcanoes because they have moved away from the hotspot.

In the Galápagos, the youngest island, Fernandina, erupted in 1995. It has been the most active volcano in the archipelago in historic time. As we collect rocks from the submarine slopes of Fernandina and Isabela, we hope to better understand the hot spot that created these “Enchanted Islands.”

Deeper Discovery

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