Researcher ORCID Identifier

Matthew Massey

Emily Morris



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The Summit 7.5-minute quadrangle is located south of Louisville and west of Elizabethtown along the boundary between Hardin and Grayson Counties and within the Mississippian Plateau physiographic region (McDowell, 1986). Topography is characterized by the low relief Pennyroyal region that sits at elevations between 560 to 650 ft above sea level, the low relief Mammoth Cave plateau at elevations between 750 to 900 ft, and the steep Dripping Springs escarpment that separates the two plains. Moore (1964) 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. The St. Louis Limestone and overlying Ste. Genevieve Limestone underlie the Pennyroyal region and are the oldest bedrock units in the quadrangle. The Beaver Bend and Paoli Limestones, Sample Sandstone, Reelsville Limestone, and Beech Creek Limestone Member of the Golconda Formation are exposed along the Dripping Springs escarpment. The Mammoth Cave plateau region is underlain by the Big Clifty Sandstone and, locally, Haney Limestone Members of the Golconda Formation east of the Summit Fault, and Hardinsburg Sandstone west of the fault. Previously mapped surficial deposits include minor areas of alluvium in tributaries across the Summit quadrangle, and areas of “slumped sandstone” (colluvium) in the Pennyroyal region (Moore, 1964).

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Spatial Coverage

Summit Quadrangle, Hardin County, Grayson County


This map was generated using new field mapping, sample analysis, elevation data from the Kentucky statewide lidar dataset (5-ft average horizontal spacing), aerial imagery, data compiled from water well logs, oil and gas records, Kentucky Transportation Cabinet geotechnical reports, and landslide inventory mapping from Crawford (2014). Sinkholes in Hardin County were identified using the random forests algorithm by Zhu and Pierskalla (2016). The extent of colluvium was determined using image classification analysis to detect areas exceeding estimated slope stability determined to be approximately 12° by field and geotechnical evidence. Samples were described by Munsell color and petrography. Grain size analysis was performed on sediment fractions of less than 2 mm with a laser particle analyzer; results were interpreted using methods discussed in Folk (1966), and grain size is reported using the modified Wentworth scale. Samples representative of major map units were analyzed by X-ray fluorescence and X-ray diffraction for bulk chemistry and mineralogy, respectively. Previously published reports by Moore (1964), Arms and others (1979), and Whitaker and others (1972) were also used for interpretation.

Funding Information

This map was generated using new field mapping along with compilation of unpublished and previously published data, and was funded in part by the U.S. Geological Survey’s National Cooperative Mapping Program under the STATEMAP program authorized by the National Geologic Mapping Act of 1992, Grant No. G21AC10834, and by the Kentucky Geological Survey.



Surficial Geologic Map of the Summit 7.5-Minute Quadrangle, Kentucky

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