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Middlesex Formation

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Middlesex Formation
Stratigraphic range: Frasnian
TypeFormation
Unit ofSonyea Group
UnderliesCashaqua Shale or Pulteney shale
OverliesGenesee Group
Thickness6–75 feet (23 m)
Lithology
PrimaryBlack Shale
Location
Region
CountryUnited States
Type section
Named forTown of Middlesex, NY

The Middlesex Formation is a carbon rich black shale geologic formation found in the Appalachian Basin. It represents one of several transgressive events (rising sea levels) during the Late Devonian.[1]

Description

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The Middlesex is a laminated, dark grey to black formation comprising mudstone and siltstone. It developed in an anoxic environment. Further evidence of this is the lack of bioturbation. There are also sparse sand and silt layers, suggesting that they were single event deposits.[2]


References

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  1. ^ KIRCHGASSER, WILLIAM T.; OVER, D. JEFFREY (9 December 2023). "FRASNIAN (UPPER DEVONIAN) STRATA OF THE GENESEE RIVER VALLEY, WESTERN NEW YORK STATE" (PDF). Otto's Website. Retrieved 9 December 2023.
  2. ^ Schieber, J. (1999-07-01). "Distribution and deposition of mudstone facies in the Upper Devonian Sonyea Group of New York". Journal of Sedimentary Research. 69 (4): 909–925. doi:10.2110/jsr.69.909. ISSN 1527-1404.