Nature
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Big Butte is a 2,500-foot-high butte formed by two overlapping rock domes that rise above the lava plain. About 300,000 years ago, a hot flow of molten rhyolite, an acidic rock, boiled up through older lava, and a second rhyolite dome later pushed up a block of earlier basalt on its northwest side. The domes took many thousands of years to reach their present shape, but in geological terms they are very recent structures.
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