Story: Volcanoes
Mayor Island (Tūhua) is the top of a large rhyolite volcano in the western Bay of Plenty. The central ring of cliffs marks the edge of a caldera formed by an explosive eruption about 7,000 years ago. The black volcanic glass known as obsidian is found in some lava flows on the island.
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GNS Science
Reference: CN9167/9
Photograph by Lloyd Homer
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