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Transcript for Exotic Terrane, segment 03 of 12
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Geologists soon learned that the Hells Canyon region was very unique geologically. It is located in some of the most rugged terrain in the Pacific Northwest. This area includes Hells Canyon and the Seven Devils and Wallowa mountain ranges. It is known as the Wallowa Terrane.
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We're sitting on the sides of an ancient volcano that at one time was under water, maybe as much as a mile under water and under ocean water.
The Wallowa Terrane contains large formations of these odd-looking rocks. They are called pillow lavas, and they only form where volcanic lava flows into water.
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Pillow lavas are forming today around many volcanic islands, including Hawaii. The pillow lavas in the Wallowa Terrane also formed in the ocean over two hundred million years ago. Today these rocks are found in the Seven Devils Mountains near Hells Canyon over nine thousand feet above sea level. The Pacific Ocean is three hundred and fifty miles away. Somehow these rocks were moved far away from their original location under the ocean.