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Pompeys Pillar National Monument

National Monument on Great Plains near Pompeys Pillar, MT

National Register of Historic Places

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Pompeys Pillar National Monument is a rock formation located in south central Montana, United States. Designated a National Monument on January 17, 2001, and managed by the U.S. Bureau of Land Management, it consists of only 51 acres (21 ha), making it one of the smallest National Monuments in the U.S. It was previously designated a National Historic Landmark on July 25, 1965. The new Pompeys Pillar Interpretive Center opened in 2006. Exhibits in the 5,700-square foot center relate the journey of Captain William Clark and his detachment, including Sacagawea and her son Pomp, down the Yellowstone River Valley in 1806. The pillar itself stands 150 feet (45 m) above the Yellowstone River and consists of sandstone from the late Cretaceous Hell Creek Formation, 75 – 66 million years ago. The…

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National Monument