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Harford County

 
  

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Wissahickon Formation Undifferentiated (Late Precambrian ?)
Volcanic Complex of Cecil County (Late Precambrian ?)
Upper Pelitic Schist (Late Precambrian ?)
Ellicott City Granodiorite (Paleozoic)
Metagraywacke (Late Precambrian ?)
Gunpowder Granite (Paleozoic)
Metaconglomerate (Late Precambrian ?)
Port Deposit Gneiss (Paleozoic)
Boulder Gneiss (Late Precambrian ?)
Relay Quartz Diorite (Early Paleozoic- Late Precambrian ?)
Lower Pelitic Schist (Late Precambrian ?)
James Run Formation (Late Precambrian ?)
Cockeysville Marble (Late Precambrian ?)
Peach Bottom Slate (Ordovician)
Setters Formation (Late Precambrian ?)
Cardiff Metaconglomerate (Ordovician)
Ultramafic Rocks (Early Paleozoic- Late Precambrian ?)
Potomac Group (Cretaceous)
Baltimore Gabbro Complex (Early Paleozoic- Late Precambrian ?)
Upland Deposits -Western Shore (Quaternary)
Baltimore Gneiss (Precambrian)
Lowland Deposits (Quaternary)
Metagabbro and Amphibolite (Early Paleozoic ?)
Ultramafic and Gabbroic Rocks (Early Paleozoic ?)
Muscovite Quartz Monzonite Gneiss (Paleozoic)
Quartz Gabbro and Quartz Diorite Gneiss (Paleozoic)