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Frederick County
Click on a tile to display information about the associated rock types or formations.
Diabase Sills and Dikes (Triassic) Antietam Formation (Cambrian) Harpers Formation (Cambrian) Weverton Formation (Late Precambrian ?) Metarhyolite and Associated Pyroclastic Sediments (Late Precambrian ?) Catoctin Metabasalt (Late Precambrian ?) Granodiorite and Biotite Granite Gneiss (Precambrian) Libertytown Metarhyolite (Late Precambrian ?) Wakefield Marble (Late Precambrian ?) Marburg Schist (Late Precambrian ?) New Oxford Formation (Triassic) Ijamville Formation (Late Precambrian ?)
Tomstown Dolomite (Cambrian) Gettysburg Shale Formation (Late Precambrian ?) Swift Run Formation (Late Precambrian ?) Grove Limestone (Cambro-Ordovician Urbana Formation (Late Precambrian ?) Frederick Limestone (Cambrian) Sugarloaf Mountain Quartzite (Late Precambrian ?) Sams Creek Metabasalt (Late Precambrian ?) Silver Run Limestone (Late Precambrian ?) Ijamville Formation / Marburg Schist (Late Precambrian ?)