Surficial Geologic Map of the Big Clifty 7.5-Minute Quadrangle, Kentucky
The Big Clifty 7.5-minute quadrangle is located south of Louisville and west of Elizabethtown along the boundary between Hardin and Grayson Counties. The quadrangle lies within the Mammoth Cave plateau of the Mississippian Plateau physiographic region (McDowell, 1986). Topography is characterized by a low relief plain sitting at elevations between 650 to 850 ft above sea level, which is dissected and incised by Rough River, Meeting Creek, Clifty Creek, and their tributaries to below 500 ft. Swadley (1962) mapped the bedrock geology of the quadrangle, which was later digitized by Conley (2002). Mississippian bedrock is exposed throughout the quadrangle and is cut by several vertical faults in the southeast. The oldest bedrock units include the Beaver Bend and Paoli Limestones, Sample Sandstone, and Reelsville Limestone from oldest to youngest, respectively, and are exposed in the lowest sections of river valleys on the west side of the quadrangle. The Golconda Formation (Beech Creek Limestone, Big Clifty Sandstone, and Haney Limestone Members) is primarily exposed along steep slopes of those same river valleys, which lead up to the top of the plateau. The majority of the broad Mammoth Cave plateau is underlain by Hardinsburg Sandstone with local exposures of Glen Dean Limestone and Leitchfield Formation occurring in the southwest corner of the quadrangle. Previously mapped surficial deposits include scattered areas of alluvium in Meeting Creek, Little Meeting Creek, and Clifty Creek (Swadley, 1962).