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Pompeys Pillar National Monument, Montana


Pompeys Pillar National Monument is a nature heritage site in Yellowstone County, Montana. The site protects a rock formation and its surrounding terrain. Covering just 51 acres (21 ha), it is one of the smallest national monuments in the United States.

Pompeys Pillar is a sandstone formation above the Yellowstone River. It is 150 feet (45 m) tall, and was formed some 75-65 million years ago. Its base covers an area of about an acre (0.4 ha). The formation holds numerous petroglyphs left behind by early Native American, as well as the graffiti of William Clark, the co-leader of the Lewis and Clark Expedition on 25 July, 1806. It was Clark who originated the name Pompys Tower for the formation. The name was modified to Pompeys Pillar in 1814.

Pompeys Pillar National Monument, MontanaPompeys Pillar National Monument, Montana
Source: https://commons.wikimedia.org/wiki/File:Pompeys_pillar_boardwalk.jpg
Author: Larry D. Moore
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Visiting Pompeys Pillar National Monument, Montana

Pompeys Pillar National Monument is about 25 miles northeast of Billings, Montana. From Billings, take Interstate 90 until Exit 456 and continue on Interstate 94, turning off at Exit 23. Then continue on US Highway 312 heading west till you see the entrance to your right. You can see Pompeys Pillar from the junction leading to the site.

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