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Flood Of Fire The sign reads..... River canyons expose the landscape's hidden excesses, it's violent past. The orderly columns across the canyon are volcanic. From vents in the Yellowstone Plateau lava welled up and flowed ---- A vast flood of fire 25 feet (7.6m) deep. As the lava cooled and contracted about 1.3 million years ago, it formed contraction cracks, producing hexagonal columns of basalt. The rock layers are a geologic photo album. Lava flows and other dynamic events have become benign scenic features, frozen in time. Above and below the basalt lies a loose mix of gravel carried here by glacial meltwater. |
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