Bellefonte Formation

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The Ordovician Bellefonte Formation (Obf) is a mapped bedrock unit in central Pennsylvania.


The Bellefonte is defined as a medium-gray, brownish-weathering, medium-bedded dolomite and minor sandstone. The very fine grained Tea Creek Member lies above, and the crystalline Coffee Run Member lies below.[1]

Depositional environment[edit]

Deposition of formations such as the Bellefonte Dolomite occurred in environments equivalent to the modern Bahama lagoons, east of Miami.[2]


Relative age dating of the Bald Eagle places it in the Ordovician period. It rests atop the Axemann Formation (Oa),[1] or the Nittany Formation, for example between Tyrone and Water Street, Pennsylvania, where the Axemann is missing, and the Loysburg Formation of interbedded limestone and dolomite conformably overlies the Bellefonte Formation.[3]

See also[edit]


  1. ^ a b "Explanation of Geologic Units" (PDF). Pennsylvania Geological Survey. Retrieved 2008-01-26. 
  2. ^ "Structures of The Appalachian Foreland Fold-Thrust Belt: Fold-Thrust Geometries of the Juniata Culmination (State College and Environs), Central Appalachians of Pennsylvania". Pennsylvania State University Department of Geosciences. Archived from the original on December 13, 2000. Retrieved 2008-01-27. 
  3. ^ "Trenton Black River Carbonates: Stop 3". Trenton and Black River Carbonates in the Union Furnace Area of Blair and Huntingdon Counties, Pennsylvania. Pennsylvania Geological Survey. Archived from the original on 27 December 2007. Retrieved 2008-01-27.