Geology of Pea Ridge National Military Park, Arkansas

Cannons on the battlefield at Pea Ridge National Military Park. NPS.

The NPS Geodiversity Atlas, a product of the Geologic Resources Inventory, summarizes each park's rocks, landforms and soils to support education, geoconservation and management. This is its page for Pea Ridge National Military Park.

The park

• Why it's here: authorized on July 20, 1956, the park commemorates a pivotal 1862 Union victory over Confederate troops — including about 1,000 Cherokee and Choctaw-Chickasaw soldiers — that kept Missouri under Union control and proved crucial to the Mississippi campaign.
• Where: 4,300.35 acres (4,278.75 federal) of rolling hills in Benton County, northwestern Arkansas, 7 km (4.5 miles) northeast of Rogers and Bentonville, plus a small, unnamed 56-acre outlying unit.

The landscape

• Setting: the park straddles the Pea Ridge and Garfield quadrangles, between the Big Sugar Creek and Little Sugar Creek drainages.
• High points: Elkhorn Mountain (over 490 m, 1,600 ft) and Round Mountain (over 460 m, 1,520 ft) — erosional remnants of a once-continuous plateau.
• The rocks: nearly flat, little-deformed sedimentary layers. The main unit is the Mississippian Boone Formation, a limestone-rich rock prone to karst — caves and sinkholes. Locally it is capped by resistant sandstone, possibly the Batesville Sandstone, which tops the region's highest hills.
• Landforms: dissected plateaus, ridges divided by valleys and ravines, and gently rolling open ground — terrain closely tied to how the battle unfolded.

A living history encampment at Pea Ridge. NPS.

Regional geology and resources

Pea Ridge belongs to the Ozark Plateaus province. The Geologic Resources Inventory offers scoping summaries, digital geologic maps, reports and posters for the park (NPS DataStore), and a Soil Resources Inventory is complete. See also the park's home page and the Arkansas Geological Survey.

Sources

Based on "NPS Geodiversity Atlas — Pea Ridge National Military Park, Arkansas," National Park Service; a work of the United States government in the public domain. The page's "Introduction" and "Geologic Setting" sections describe a different park, Ozark National Scenic Riverways, and are left out.