This layer contains data concerning the location and characteristics of bedrock, mappable geologic units, within Frederick county. This geodatabase contains geologic data from Frederick County, Maryland. Data from several geologic quadrangles and two regional scale geologic maps were incorporated into the regional scale geologic feature classes in this geodatabase. Because of the scale of this map, some features were generalized slightly from the quad scale data. Additionally, some corrections were made for accuracy, such as edge matching to resolve "border faults". The source data for this map and geodatabase come from maps published by the Maryland Geological Survey from 2001 to the present, as well as one map published in cooperation with the United States Geological Survey. The source maps are Buckeystown (2001), Catoctin Furnace (2004), Frederick (2004), New Windsor (2004), Point of Rocks (2004), Walkersville (2004), Woodsboro (2004), Middletown (2005), Union Bridge (2006), Funkstown (2009), Keedysville, Shepherdstown, Charlestown, and Harpers Ferry (2009), Myersville and Smithsburg (2009), Hagerstown (2013), Mason and Dixon (2013), Clear Spring and Hedgesville (2014), Williamsport (2014), Blue Ridge Summit (2021, in review), Emmitsburg and Taneytown (2021, in review), all 1:24000 quadrangle scale, as well as portions of two regional maps: Geologic Map of Garrett, Allegany, and Western Washington Counties, Maryland (2013), and Geologic Map of the Frederick 30' x 60' Quadrangle, Maryland, Virginia, and West Virginia (USGS, 2007). The GIS data from the referenced maps were mosaiced in Arc Map, corrected for accuracy across quad boundaries, merged to form a continuous dataset and clipped to the extent of Frederick County. Feature level metadata are included, which contain field descriptions for each feature class. This is a small scale dataset, appropriate for 1:100,000 regional scale. Quad scale data are suggested for display or analysis that requires a larger scale. This dataset is prepared for compliance with the USGS GeMS database standard. Last Updated: 06/01/2022