Hawaii Tribune-Herald EAST HAWAII F.A.Q. BOOK Sunday, September 13, 2015 5 And how did it form? Hawaii Island, along with the other islands in the Hawaiian archipelago, was forged over what scientists call a “hot spot,” an unusually hot area between the Earth’s crust and mantle. More than 70 million years ago, magma upwelling through the hot spot emerged on the seafloor and built up a seamount during hundreds of thousands of years until it broke the surface. Once the eruptions reached a height where they no longer could be affected by the waves, the eruptions became gentle and effusive, forming broad shieldshaped mountains. Sometimes, the islands would be comprised of single volcanoes, and others would be formed of volcanoes whose lavas overlapped. As the islands moved away from the hot spot, the volcanic eruptions changed their character, becoming less frequent and more alkaline. Photo by HOLLYN JOHNSON/Tribune-Herald How old is the Big Island? See OLD Page 6
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