The Devonian Catskill Formation or the Catskill Clastic Wedge is a unit of mostly terrestrial sedimentary rock found in Pennsylvania and New York. Minor marine layers exist in this thick rock unit (up to ). It is equivalent to the Hampshire Formation of Maryland, West Virginia, and Virginia.
The Catskill is the largest bedrock unit of the Upper Devonian in northeast Pennsylvania and the Catskill region of New York, from which its name is derived. The Pocono Mountains of Pennsylvania are largely underlain by this unit as well. The rocks of the Catskill are a clastic wedge of predominantly red sandstone, indicating a large-scale terrestrial deposition during the Acadian orogeny. Many beds are cyclical in nature, preserving the record of a dynamic environment during its approximately 20 million years of deposition.
The Catskill Formation preserves a highly diverse paleobiota, including many early sarcopterygians (especially tetrapodomorphs), providing important evidence about the evolution of terrestrial vertebrates. The formation also provides important fossils about the evolution of land plants.
Geology
Depositional environment
During the Devonian period, the Catskill Delta was formed by a series of river deltas and otherwise marshy terrain. This terrain was sandwiched between the epicontinental Kaskaskia Sea in central North America and the now-vanished Acadian Mountains. Erosion brought sediment from the mountain westwards into the sea, forming the deltas.
Eventually, the Delta formation was buried and transformed into sandstone, which was then revealed in places when the Catskill and Appalachian Mountains were formed at a later date. This transformation and uncovering is the primary reason why the Catskill Delta is notable in the present. Western Pennsylvania's petroleum was formed as a consequence. This was the first major oil region to be developed.
The Catskill was once considered to be related to the Old Red Sandstone, but in actuality, the two are only coincidentally similar. Both formed at approximately the same time, and under similar conditions: to the north of the Acadian Mountains were the Caledonian Mountains, and a similar region of marsh and river delta formed there.
Glacial erosion Though both mountain ranges were formed during the Acadian orogeny, the Catskill Mountains, unlike the Appalachian Mountains underwent glacial erosion. Much of what formed the Catskills as they stand today is a result of the Wisconsin glaciation which ended only about 12,000 years ago.
There are many signs of the Glacial period event which carved the current day Catskill Mountains.
These markers include:
Glacial Erratics such as the Devils Tombstone Striations "Dance Floors" such as Pratt Rock Terminal moraines
Members
Eastern Pennsylvania Towamensing, Walcksville, Beaverdam Run, Long Run, Packerton, Poplar Gap, Sawmill Run, Berry Run, Clarks Ferry, and Duncannon.
Central Pennsylvania Irish Valley, Sherman Creek, Buddys Run, Clarks Ferry, and Duncannon.
Paleobiota
Plants
Plantae Name Species Locality Material Notes Images Taeniocrada sp Catskill Formatiom, Potter County >80 Specimens Barinophyton citrulliforme Catskill Formation, Potter County, Pennsylvania >20 specimens cf. obscurum Catskill Formation, Potter County, Pennsylvania ssp. Catskill Formation, Potter County, Pennsylvania >100 Specimens Protobarinophyton P. pennsylvanicum Catskill Formation, Potter County, Pennsylvania 2 Specimens of megaspore The genus these spore are attached to belong to an early group of land plants from the Silurian. Rhacophyton Lycopsida Indeterminate Catskill Formation, Potter County, Pennsylvania 8 Specimens Archaeopteris A.ssp Catskill Formation, Potter County, Pennsylvania >160 Specimens One of the earliest known large "tree" like plants to take root
Invertebrates
Protostomes Name Species Locality Material Notes Images Lingula sp Catskill Formation, Potter County, Pennsylvania 1 Specimen Gigantocharinus G.szatmaryi Red Hill Locality, Clinton County, Pennsylvainia Holotype consists of an extremely well preserved exoskeleton and a few impressions. The genus has helped begin bridging the gap between its family's missing record from the Middle Devonian to the Late Carboniferous. Orsadesmus O.rubecollus Red Hill Locality, Clinton County, Pennsylvainia Holotype is an impression of the exoskeleton The species was described alongside the Quebec genus Zanclodesmus, forming a new family within the broad flat keeled members of the order Archidesmida. Hallipterus H.excelcior Catskill Formation, Wyoming County, Pennsylvania Adelophthalmus A.ssp Catskill Formation, Potter County, Pennsylvania 1 Specimen It was described in 2002 by W. E. Stein (2002) as an indeterminate Eurypterid, it was then redescribed as an indeterminate species of Adelophthalmus in 2022 by R. E. Plotnick (2022).
Placoderms
Placoderms of the Catskill FormationGenusSpeciesPresenceMaterialNotesImagesBothriolepisB. sp. Mansfield, Tioga County, PennsylvaniaAbundant material, including mass mortality of hatchlings.A bothriolepidid. Species unknown, though sometimes referred to as B. nitida.GroenlandaspisG. pennsylvanicaA groenlandaspidid.PhyllolepisP. rossimontinaA phyllolepidid.P. thomsoniArticulated skeleton.TurrisaspisT. elektorA groenlandaspidid.
Acanthodians Acanthodians of the Catskill FormationGenusSpeciesPresenceMaterialNotesImagesGyracanthusG. cf. sherwoodiA gyracanthid.
Chondrichthyans Chondrichthyans of the Catskill FormationGenusSpeciesPresenceMaterialNotesImagesAgeleodusA. pectinatus Red Hill Locality, Clinton County, PennsylvainiaTeethA holocephalan of uncertain affinities.CtenacanthusC. sp.A ctenacanthiform elasmobranch.
Actinopterygians Actinopterygians of the Catskill FormationGenusSpeciesPresenceMaterialNotesImagesLimnomisL. delaneyi Red Hill, Clinton County, Pennsylvania Holotype is a compressed skull.An early ray-finned fish.
Sarcopterygians Sarcopterygians of the Catskill FormationGenusSpeciesPresenceMaterialNotesImagesApatorhynchusA. opistheretmus Apatorhynchus-type locality, Tioga County, Pennsylvania Holotype is a partial skull, 1 specimen.A lungfish of uncertain affinities.DensignathusD. roweiA stegocephalian tetrapodomorph.EusthenodonE. bourdoniA tristichopterid tetrapodomorph.E. leganihanneHyneriaH. lindae Red Hill Site, Clinton County, Pennsylvainia Holotype is a disarticulated skull and 3D body fossil.A tristichopterid tetrapodomorph.HynerpetonH. bassettiA stegocephalian tetrapodomorph.LanglieriaL. radiataA tristichopterid tetrapodomorph. Originally identified as Holoptychius.L. smalingiIrish Valley MemberMegalichthysM. mullisoniA megalichthyid tetrapodomorph.SauripterusS. taylori Sherman Creek Locality, Lycoming County, Pennsylvainia The Holotype is an articulated limb and 3 scales, there are 3 individuals.A rhizodontid tetrapodomorph.T.A. Stewart, J.B. Lemberg, N.K. Taft, I. Yoo, E.B. Daeschler,& N.H. Shubin, Fin ray patterns at the fin-to-limb transition, Proc. Natl. Acad. Sci. U.S.A. 117 (3) 1612-1620,(2020). Marcus C. Davis, Shubin, N., & Daeschler, E. B. (2004). A New Specimen of Sauripterus taylori (Sarcopterygii, Osteichthyes) from the Famennian Catskill Formation of North America. Journal of Vertebrate Paleontology, 24(1), 26–40.SoederberghiaS. groenlandica Catskill Formation, Lycoming County, PennsylvaniaA rhynchodipterid lungfish.SterropterygionS. brandeiAn indeterminate osteolepiform tetrapodomorph.
References
External links Depositional environments in the Catskill Clastic Wedge Devonian Times Website summarize about Red Hill Shale in Catskill Formation