The Hawai'i archipelago is the product of the interplay of plate tectonics—the shifting of the Earth’s outer, rigid crust—with a plume of molten material welling up from the Earth’s mantle, a hotspot.
The Hawaiian islands formed sequentially as the Pacific plate moved to the northwest over this hotspot. The upwelling magma erupted as basaltic flows on the ocean floor that eventually built up thousands of feet to breach the surface and form an island.
As the Pacific plate continued its movement to the northwest, the new island moved off the hot spot, and volcanic activity ceased. Once volcanic activity ceased, no new rock was added to the island, and surface processes, the action of wind and waves, became the dominant processes in shaping the island, and the quieted volcanic island began to succumb to erosion, eventually disappearing beneath the waves.
Photo: the southern coast of the Big Island takes a pounding from the waves.
No comments:
Post a Comment