The Galapagos Islands are close to three divergent plate boundaries.
Divergent plate boundaries are zones where two or more of the Earth's tectonic plates move away from each other. The movement extends and fractures the Earth's crust. The driving forces for the motion are convection currents that rise from the Earth's hot core and carry molten magma towards the base of the plates. At this position, lateral motion from the convection currents pushes the plates apart. Molten magma from the Earth's mantle fills in the spaces between the plates and creates a new crust.
Rift Valley
As magma rises from the Earth's mantle, it elevates and stretches the crust. When the stretching forces exceed the strength of the crust, the crust breaks along two dominant fracture zones. The crust between these zones falls down producing a rift valley. Molten magma intrudes along the fracture zones and flows into the new valley. The East African Rift Valley, which extends from southern Africa and northwards to Egypt, and the Rio Grande Rift between Colorado and Mexico, are examples of crustal divergence.
Linear Sea
As crustal separation continues, the crust breaks apart completely and the rift valley deepens and lengthens. The sea enters the new space and creates a narrow, linear sea. Examples of these are the Gulf of California between Baja California and mainland Mexico, and the Red Sea that separates Africa from the Arabian Peninsula.
Mid-Oceanic Ridge
Further spreading enlarges the linear seas into greater expanses of water and oceans. The boundary between the divergent plates becomes a mid-oceanic ridge. The mid-Atlantic Ridge that separates Africa and Europe from North and South America is the longest such feature. Similar features occur in the Indian, Pacific and Arctic Oceans as well as the Antarctic Sea.
Triple Junction
The zone from which three tectonic plates diverge is a triple junction. The Galapagos Triple Junction in the eastern Pacific Ocean is one example. Here, the Cocos, Nazca and Pacific plates spread away from each other while at the same time rotating around two other microplates.
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