Geologic Group found in the Appalachian Basin
Helderberg Group |
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Stratigraphic range: Lochkovian-Emsian ~419–393 Ma PreꞒ Ꞓ O S D C P T J K Pg N |
Type | Group |
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Sub-units | - Port Ewen Shale
- Minisink Limestone
- New Scotland Formation
- Maskenozha Member
- Flatbrookville Member
- Coeymans Formation
- Kalkberg / Stormsville Members
- Shawnee / Revanna Members
- Depue Limestone Member
- Peters Valley Member
- Manlius Limestone
- Thacher Member
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Underlies | - Onondaga Limestone
- Oriskany Formation
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Overlies | |
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Lithology |
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Primary | Limestone |
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Other | Dolomite, Chert |
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Location |
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Region | |
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Country | United States |
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Type section |
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Named for | Helderberg Escarpment |
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Named by | Conrad, T.A. 1839 |
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The Helderberg Group is a geologic group that outcrops in the State New York, Pennsylvania, Maryland, New Jersey, and West Virginia. It also is present subsurface in Ohio and the Canadian Providence of Ontario It preserves fossils dating back to the Early Devonian and Late Silurian period. The name was coined by T.A Conrad, 1839 in the New York State Geological Survey Annual Report. Named for the Helderberg Escarpment or Helderberg Mountains.[1]
The upper portion of the Helderberg, or the Kalkberg Formation is host to the Bald Hill ash bed, dated to 417.6 million years ago.[2]
The Helderberg is composed chiefly of limestone and dolomite.[3]
In Maryland and southern Pennsylvania, the Helderberg is divided into three formations. These are the New Creek Limestone, the Corriganville Limestone, and the Mandata Shale. The total thickness is about 60 feet. The formations weather easily and are poorly exposed except in cuts and quarries.[4]
Stratigraphy
Manlius Limestone
The Manlius Limestone was first noted by Vanuxem (1840, p. 372) as a "waterlime" (hydraulic limestone) near Manlius, New York.[5] The Manlius is composed of limestone, grainstone, calcareous mudstone and bindstone. The Manlius is 419 - 411 Ma.[6]
The Thacher Member member of the Manlius along eastern New York and down into parts of northern New Jersey. It is characterised as a "ribbon rock", meaning that it contains very thin layers of alternating limestone and argillaceous rock. The color of the Thacher is dark blueish-black. The limestone is fine to medium grained. It averages 51 feet thick. It makes up the upper part of the Manlius in New York and makes up the entirety of the Manlius in northeastern New Jersey. Moving southwest it become more argillaceous and arenaceous, as it grades into the Depue Limestone.[citation needed]
The Thacher contains fossils of stromatoporoids, crinoids, rugose corals, tabulate corals, tranchiopods, tentaculitids, and ostracodes.
References
- ^ Berdan, Jean. "The Helderberg Group and the Position of the Silurian-Devonian Boundary in North America" (PDF). United States Geological Survey.
- ^ Ver Straeten, Charles; Ebert, James R.; Bartholomew, Alex; Benedict, Lucas; Matteson, Lucas; Shaw, George. "DEVONIAN STRATIGRAPHY AND K-BENTONITES IN THE CHERRY VALLEY – SCHOHARIE VALLEY REGION". Research Gate.
- ^ Demicco, Robet V.; Smith, Jason. "COMPARATIVE SEDIMENTOLOGY OF THE HELDERBERG GROUP IN CENTRAL NEW YORK" (PDF). New York State Geological Association.
- ^ Glaser, J.D., and Brezinski, D.K., 1994, Geologic map of the Cumberland quadrangle, Allegany County, Maryland, Maryland Geological Survey, Scale 1:24,000.
- ^ EPSTEIN, ANITA G.; EPSTEIN, JACK B.; SPINK, WALTER J.; JENNINGS, DAVID S. (1967). "Upper Silurian and Lower Devonian Stratigraphy of Northeastern Pennsylvania, New Jersey, and Southeasternmost New York". Geological Survey Bulletin. 1243 – via Rutgers Libraries.
- ^ "Manlius Limestone, New York, USA". Mindat. 20 March 2024.
Ph | Pz | D | |
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S | |
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O | Upper | Katian | - Denley Formation
- Hillier Formation
- Indian Castle Shale
- Rust Formation
- Steuben Formation
- Sugar River Formation
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Sandbian | |
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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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