Pompey’s Pillar

A large sandstone outcrop rising from the plains along the Yellowstone River, Pompey’s Pillar was a landmark and signpost for Indigenous peoples long before William Clark carved his initials into it in 1806. Climate change influenced weather threatens the petroglyphs on the rock.

NPS

Traveling down the Yellowstone River on their return journey, Captain William Clark and a small part of the expedition crew stopped at this site on July 25, 1806. Clark measured the sandstone outcrop, ascended to the top, and carved his own name and date among the Indigenous petroglyphs. In his journal, he remarked on the beautiful countryside and the bountiful game there.20

Since Clark surveyed the landscape from the top of the pillar, climate change has affected the environment and the wildlife he would have encountered there. Increased drought, higher temperatures, and more frequent wildfires have reduced the sagebrush steppe and threaten the greater sage-grouse that rely on that habitat. Warming water temperatures make the Yellowstone River less habitable for native trout and promote the incursion of smallmouth bass. The petroglyphs on the pillar are also threatened by weathering from wind, moisture, and temperature changes that are likely worsening with climate change.21

Citations:
20 NPS, “Pompeys Pillar,” Pittsburgh to the Pacific: High Potential Historic Sites of the Lewis and Clark National Historical Trail, 2022, 105, https://www.nps.gov/lecl/getinvolved/upload/2022_LCNHT_HPHS_Report_508compliantUPDATE-2.pdf; William Clark, July 25, 1806 entry, in Gary E. Moulton, Journals of the Lewis and Clark Expedition, https://lewisandclarkjournals.unl.edu/item/lc.jrn.1806-07-25.
21 Defenders of Wildlife, “Comments on Billings and Pompey’s Pillar National Monument Draft Resource Management Plan and Environmental Impact Statement,” accessed August 26, 2024, https://defenders.org/sites/default/files/publications/Billings-Pompeys-Pillar-Sage-Grouse-Planning-Matrix.pdf; Brandon Butler, “Yellowstone River is an Example of Changing Biodiversity,” The Republic (March 11, 2022), https://www.therepublic.com/2022/03/11/yellowstone-river-is-an-example-of-changing-biodiversity/; Brett French, “BLM Considering Plan to Stabilize Landmark Pompeys Pillar,” Daily Inter Lake, February 13, 2022, https://dailyinterlake.com/news/2022/feb/13/blm-considering-plan-stabilize-landmark-pompeys-pi/; NPS, “Foundation Document: Petroglyph National Monument, New Mexico,” August 2017, https://www.nps.gov/petr/learn/management/upload/PETR_FoundationDocument-2017.pdf.

Climate Change:Lewis and Clark Trail

Lewis and Clark NHT Visitor Centers and Museums

This map shows a range of features associated with the Lewis and Clark National Historic Trail, which commemorates the 1803-1806 Lewis and Clark Expedition. The trail spans a large portion of the North American continent, from the Ohio River in Pittsburgh, Pennsylvania, to the mouth of the Columbia River in Oregon. The trail is comprised of the historic route of the Lewis and Clark Expedition, an auto tour route, high potential historic sites (shown in black), visitor centers (shown in orange), and pivotal places (shown in green). These features can be selected on the map to reveal additional information. Also shown is a base map displaying state boundaries, cities, rivers, and highways. The map conveys how a significant area of the North American continent was traversed by the Lewis and Clark Expedition and indicates the many places where visitors can learn about their journey and experience the landscape through which they traveled.