Pennsylvania Geologic Formation
| Bellefonte Formation |
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| Stratigraphic range: Lower Ordivician |
| Type | Formation |
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| Unit of | Beekmantown Group |
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| Sub-units | - Tea Creek Mbr
- Coffee Run Mbr
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| Underlies | Loysburg Formation |
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| Overlies | Axeman Formation |
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| Thickness | 50' - 2,145' |
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| Lithology |
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| Primary | Dolomite, Limestone |
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| Other | Sandstone, Chert |
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| Location |
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| Region |  Maryland Pennsylvania Virginia
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| Country | United States |
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| Type section |
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| Named for | Bellefonte, Pennsylvania |
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The Ordovician Bellefonte Formation is a mapped bedrock unit in central Pennsylvania. It is the uppermost unit of the Beekmantown Group. The top of the Bellefonte is marked by the Knox Unconformity.
Description
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] The Tea Creek Member is a medium gray argillaceous limestone. While still a limestone it does have a high magnesium content. Mostly devoid of fossils. Beds of Chert maybe found about a third of the way through the Tea Creek Member.[2]
Depositional environment
Deposition of formations such as the Bellefonte Dolomite occurred in environments equivalent to the modern Bahama lagoons, east of Miami.[3]
Age
Relative age dating of the Bald Eagle places it in the Ordovician period. It rests atop the Axemann Formation,[1] or the Nittany Formation. An example of this, is between Tyrone and Water Street, Pennsylvania. Here the Axemann is missing, and the Loysburg Formation conformably overlies the Bellefonte Formation.[4]
See also
References
- ^ a b "Explanation of Geologic Units" (PDF). Pennsylvania Geological Survey. Archived from the original (PDF) on April 22, 2003. Retrieved 2008-01-26.
- ^ ULRICH, E. O. (1911-01-01). "Revision of the Paleozoic systems". Geological Society of America Bulletin. 22 (1): 281–680. doi:10.1130/gsab-22-281. ISSN 0016-7606.
- ^ "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.
- ^ "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.
| Ph | | Pz | | P | | Cisuralian | - Dunkard Group
Greene Formation:
- Windy Gap Limestone
- Windy Gap Coal
- Gilmore Sandstone
- Nineveh Sandstone
- Nineveh Coal
- Nineveh Limestone
- Fish Creek Sandstone
- Claysville Limestone
- Dunkard Coal
- Prosperity Limestone
- Tenmile Coal
- Donley Limestone
- Upper Washington Coal
- Rockport Member
Washington Formation:
- Upper Washington Limestone Member
- Jollytown Limestone Member
- Jollytown Coal
- Middle Washington Limestone Member
- Washington Coal
- Lower Washington Limestone Member
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| C | | ⁋ | | Gzhelian | - Dunkard Group
Waynesburg Formation:
- Upper Waynesburg Member
- Little Washington Coal
- Waynesburg“B” coal
- Middle Waynesburg Member
- Waynesburg“A” coal
- Lower Waynesburg Member
- Monongahela Group
Uniontown Formation:
- Waynesburg coal "No. 11 Coal"
- Gilboy Sandstone Member
- Little Waynesburg Coal
- Waynesburg Limestone Member
- Uniontown Sanstone Member
- Annabelle Shale Member
- Uniontown Coal "No. 10 Coal"
- Uniontown Limestone Member "Great Lime"
- Fulton Shale Member
Pittsburgh Formation:
- Benwood Limestone
- Upper Sewickley Coal
- Upper Sewickley Sandstone Member
- Sewickley Coal "Meigis Creek" "No. 9 Coal"
- Lower Sewickley Sandstone Member
- Sewickley Limestone Member
- Cedarville Sanstone Member
- Redstone-Pomeroy coal "No 8a. Coal"
- Westone Sanstone Member
- Pittsburgh coal seam "No. 8 Coal"
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| Kasimovian | - Conemaugh Group
Casselman Formation:
- Upper Pittsburgh Limestone Member
- Little Pittsburgh coal seam
- Lower Pittsburgh Limestone Member
- Connellsville Member
- Morgantown Member
- Birmingham Member
- Glenshaw Formation
- Ames Limestone
- Pittsburgh Red Beds
- Upper Bakerstown coal
- Upper Saltsburg Sandstone Member
- Woods Run Limestone Member
- Lower Saltsburg Sandstone Member
- Pine Creek Limestone Member
- Buffalo Sandstone Member
- Bush Creek Limestone Member
- Mahoning Formation
- Bush Creek Coal
- Upper Mahoning Sandstone Member
- Mahoning Coal "No. 7a Coal"
- Lower Mahoning Sandstone Member
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| Moscovian | - Allegheny Group
Freeport Formation:
- Upper Freeport Coal "No. 7 Coal"
- Upper Freeport Limestone Member
- Butler Sandstone Member
- Lower Freeport Coal "No. 6a Coal"
- Upper Freeport Limestone Member
- Freeport Sandstone Member
- Kittanning Formation
- Upper Kittanning Coal
- Johnstone Limestone Member
- Middle Kittanning Coal "No. 6 Coal"
- Lower Kittanning Coal "No. 5 Coal"
- Kittanning Sandstone Member
- Clarian Formation
- Clarian Coal "No. 4a Coal"
- Vanport Limestone Member
- Brookville Coal "No. 4 Coal"
- Brookville Member
- Pottsville Group
Beaver River Formation:
- Homewood Sandstone Member "1st Salt Sand"
- Mercer Formation
- Upper Mercer Limestone Member
- Upper Mercer Coal
- Lower Mercer Limestone Member
- Lower Mercer Coal "No. 3 Coal"
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| Bashkirian | - Pottsville Group
Connoquenessing Formation:
- Upper Connoquenessing Sandstone Member "2nd Salt Sand"
- Quakertown Coal "No. 2 Coal"
- Quakertown Fire Clay
- Quakertown Shale
- Lower Connoquenessing Sandstone Member
- Sharon Formation
- Sharon Shale Member
- Sharon Coal "No. 1 Coal"
- Sharon Sandstone
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| M | |
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| D | | Upper | | Famennian | - Venango Group
- Gantz, Hundred-foot sand, Fifty-foot sand, Thirty-foot sand, Nineveh-Snee, Gordon Stray, Fourth Sand, Fifth Sand, Bayard Sand, Elizabeth Sand, Sweet Richard,
- Chadakoin Formation, First Warren
- Bradford Group
- Upper Warren, Lower Warren, Speechely Stray, Speechely, Balltown A, Balltown B, Balltown C, Sheffield, First Bradford, Second Bradford, Third Bradford, Kane
- Elk Group
- 1st Elk Sand, 2nd Elk Sand, 3rd Elk Sand, 4th Elk Sand, 5th Elk Sand
- Ohio Shale
- Catskill Group
- Duncannon Member
- Sherman Creek Member
- Irish Valley Member
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| Frasnian | |
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- Knapp Conglomerate
- Murrysville Sandstone
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| Middle | |
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| Lower | |
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| S | |
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| O | |
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| Є | |
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| pЄ | Grenville Complex |
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