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Black Hills in Rapid City, South Dakota | by gojcajel
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Black Hills in Rapid City, South Dakota

Due to volcanic activity thousands of years ago, the Black Hills are mostly formed of sandstone and are beautiful because of the unique sharp spikes. The “bulls eye” of the Black Hills contains mostly granite and is billions of years old based on the number of rings formed on the rocks.

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Uploaded on October 22, 2014