The group of volcanic islands making up the Galapagos are about 1000 km. west of the coast of South America. Some 2900 km. underneath these islands at the junction of the mantle and the earth's iron central core plumes of hot rock rise to the surface. Part of this plume melts and penetrates the relatively thin outer layer or lithosphere giving rise to volcanic eruptions. This mantle plume coupled with the thickening of the lithosphere pushes the volcano above the surface. While the plume moves upward, the lithosphere is moving slowly toward the South American coast. This causes a chain of islands to be formed immediately above the rising plumes. The Hawaiian Islands formed in much the same manner.
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