The Flynn Creek impact structure was originally recognized in 1968 by David Roddy as one of the original six confirmed impact structures on Earth. The Flynn Creek impact structure is also the first recognized marine-target impact structure. Exposure at Flynn Creek varies, as there is no obvious rim and the geological map of the area does not look like a crater. But, there is an impact breccia unit dominated by two classes of breccia—the lower, chaotic, slump breccia and the upper graded resurge breccia. The post-impact unit is Chattanooga Shale, of which one facies is present only in the...