The Weaubleau structure in western Missouri is a probable meteorite impact site, about 12 miles across, marked by severe deformation and extensive brecciation from a violent event roughly 335 to 340 million years ago. A meteoroid about 1,200 feet wide likely struck here during the middle Mississippian Period. Its circular form was later identified by geologist Kevin R. Evans using digital elevation data, strengthening the impact interpretation. Burial by later sediments and only recent erosion helped preserve the site and make its age easier to estimate. Though still classified as probable, it is regarded as one of Earth’s 50 largest known impact structures and the largest exposed untectonized one in the United States.