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Geology

Rattlesnake Mountain Afternoon

"The monument is equally rich in geologic history, with dramatic landscapes that reveal the creative forces of tectonic, volcanic, and erosive power . . . the monument contains significant geological and paleontological objects. The late-Miocene to late-Pliocene Ringold Formation, known as the White Bluffs, was formed from river and lake sediments deposited by the ancestral Columbia River and its tributaries. These striking cliffs form the eastern bank of the Columbia for nearly half of the length of the Reach, and are significant for the mammalian fossils that they contain. Fossil remains from rhinoceros, camel, and mastodon, among others, have been found within these bluffs.

The Hanford Dune Field, located on the western shore of the Columbia in the southeastern part of the monument, is also of geologic significance. This active area of migrating barchan dunes and partially stabilized transverse dunes rises 10 to 16 feet above the ground, creating sandy habitats ranging from 2 to several hundred acres in size." — President William Clinton, June 9, 2000, in the Presidential Proclamation creating the Hanford Reach National Monument.

  • Lava Flows

    Basalt Columns

    For millions of years, the inland Northwest was shaped, then reshaped, then reshaped again and again, by lava flooding from the earth's core.

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  • Ancestral Columbia River

    White Bluffs Deposits

    The ancient Columbia River dominated the landscape millions of years ago, much as it does today, and laid the foundation for the signature White Bluffs.

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  • Paleontology

    Fish Fossil

    Mammoths and camels and rhinoceroses (rhinoceri?) once lived here, and their fossils are here to tell the tale.

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  • Ice Age Floods

    Glacial Erratic

    Imagine half the volume of Lake Michigan roaring through central Washington in a week, an 80-mile-per-hour wall of water destroying in one spot, building in another.

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  • Landslides

    Landslide Hazard Sign

    Modern irrigation has brought us many wonderful things, but it's also brought new problems to solve, one of which is a dramatic acceleration of landslides along the White Bluffs.

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  • Special Geologic Features

    Hanford Sand Dune

    A landscape resembling Mars, sand dunes to rival those of the Great Lakes, the remnants of the Ice Age Floods, the Monument has a special geologic history reflected in the land.

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Page Photo Credits — Rattlesnake Mountain - Environmental Molecular Sciences Laboratory, Basalt Columns - Seth M, Hanford Sand Dune - Heather
Last Updated: May 20, 2013
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