GEOLOGY OF THE PEA RIDGE NATIONAL MILITARY PARK

The geologic setting of Pea Ridge Battlefield played an important role in the outcome of the battle at Pea Ridge, Arkansas. The battle at Pea Ridge was one of the largest and most decisive Civil War battles west of the Mississippi River. Over 26,000 soldiers struggled for two days in northwest Arkansas in the battle that would decide the fate of Missouri. Control of Missouri was the key to winning the war in the west. Recent STATEMAP geologic mapping was conducted on the Pea Ridge 7.5-minute Quadrangle containing the Pea Ridge National Military Park. The battlefield is located on the Springfield Plateau surface, consisting of a relatively flat or gently rolling topography which is capped by the Mississippian Boone Limestone. Elkhorn Mountain is one of two hills of small areal extent in the battlefield area that rise above the Springfield Plateau surface. Both hills are capped by the more erosion-resistant Mississippian Wedington Sandstone Member of the Fayetteville Shale. Elkhorn Mountain provided the confederate soldiers shelter and a bird’s eye view of the plateau surface below where Union army were amassing. At the time the 30-foot tall bluffs seemed like a good natural defense but later they became a death trap.