Catskill Formation
Unit of sedimentary rock in the US
title: "Catskill Formation" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["geologic-formations-of-new-york-(state)", "geologic-formations-of-pennsylvania", "devonian-pennsylvania", "devonian-system-of-north-america", "devonian-geology-of-pennsylvania", "devonian-geology-of-new-york-(state)", "devonian-southern-paleotemperate-deposits", "sandstone-formations-of-the-united-states", "shale-formations-of-the-united-states", "siltstone-formations-of-the-united-states", "deltaic-deposits"] description: "Unit of sedimentary rock in the US" topic_path: "philosophy" source: "https://en.wikipedia.org/wiki/Catskill_Formation" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Unit of sedimentary rock in the US ::
::data[format=table title="Infobox rockunit"]
| Field | Value |
|---|---|
| name | Catskill Formation |
| image | Catskill1.jpg |
| caption | Outcrop of the Irish Valley Member of the Catskill Formation along the Horseshoe Curve, Blair County, Pennsylvania |
| type | sedimentary |
| age | |
| period | Devonian |
| prilithology | Sandstone |
| otherlithology | Siltstone, shale |
| namedfor | Catskill Mountains, New York |
| region | Appalachian Mountains |
| country | United States |
| underlies | Rockwell Formation, Huntley Mountain Formation, Pocono Formation, Spechty Kopf Formation |
| overlies | Foreknobs Formation, Lock Haven Formation, Trimmers Rock Formation |
| thickness | Up to 10000 ft |
| extent | Pennsylvania, New York (state) |
| :: |
| name = Catskill Formation | image = Catskill1.jpg | caption = Outcrop of the Irish Valley Member of the Catskill Formation along the Horseshoe Curve, Blair County, Pennsylvania | type = sedimentary | age = | period = Devonian | prilithology = Sandstone | otherlithology = Siltstone, shale | namedfor = Catskill Mountains, New York | namedby = | region = Appalachian Mountains | country = United States | coordinates = | unitof = | subunits = | underlies = Rockwell Formation, Huntley Mountain Formation, Pocono Formation, Spechty Kopf Formation | overlies = Foreknobs Formation, Lock Haven Formation, Trimmers Rock Formation | thickness = Up to 10000 ft | extent = Pennsylvania, New York (state) | area = | map = | map_caption =
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 10000 ft). 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
::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b4/Catskill-slab-new.jpg" caption="Susquehanna County]], Pennsylvania, showing mud clasts within sandstone"] ::
::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/8f/Meandering_catskill_MCR1.JPG" caption="Point bar deposits in the Catskill Formation (Devonian) near North Bend, PA."] ::
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.
|author1=Boughton, Carol J. |author2=McCoy, Kurt J. | publisher = U.S. Geological Survey | year = 2006 | title = Hydrogeology, Aquifer Geochemistry, and Ground-Water Quality in Morgan County, West Virginia |journal=USGS Report |series=Scientific Investigations Report |page=81 |doi=10.3133/sir20065198 |doi-broken-date=20 January 2026 |bibcode=2006usgs.rept...81B | url = https://pubs.usgs.gov/sir/2006/5198/ | id= Scientific Investigations Report 2006-5198 |url-access=subscription }}|100%|left}}
Paleobiota
Plants
::data[format=table]
| 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
::data[format=table]
| 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
::data[format=table]
| Placoderms of the Catskill Formation | Genus | Species | Presence | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Bothriolepis | B. sp. | Mansfield, Tioga County, Pennsylvania | Abundant material, including mass mortality of hatchlings. | A bothriolepidid. Species unknown, though sometimes referred to as B. nitida. | [[File:Bothriolepis canadensis (2024).png | frameless]] |
| Groenlandaspis | G. pennsylvanica | A groenlandaspidid. | [[File:Groenlandaspis pennsylvanica.JPG | frameless]] | ||
| Phyllolepis | P. rossimontina | A phyllolepidid. | [[File:Phyllolepis12DB.jpg | frameless]] | ||
| P. thomsoni | Articulated skeleton. | |||||
| Turrisaspis | T. elektor | A groenlandaspidid. | [[File:Turrisaspis elektor.jpg | frameless]] | ||
| :: |
Acanthodians
::data[format=table]
| Acanthodians of the Catskill Formation | Genus | Species | Presence | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Gyracanthus | G. cf. sherwoodi | A gyracanthid. | [[File:Gyracanthus NT small cropped.png | frameless]] | ||
| :: |
Chondrichthyans
::data[format=table]
| Chondrichthyans of the Catskill Formation | Genus | Species | Presence | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Ageleodus | A. pectinatus | Red Hill Locality, Clinton County, Pennsylvainia | Teeth | A holocephalan of uncertain affinities. | [[File:Ageleodus pectinatus.jpg | frameless |
| Ctenacanthus | C. sp. | A ctenacanthiform elasmobranch. | [[File:Ctenacanthus concinnus.png | frameless]] | ||
| :: |
Actinopterygians
::data[format=table]
| Actinopterygians of the Catskill Formation | Genus | Species | Presence | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Limnomis | L. delaneyi | Red Hill, Clinton County, Pennsylvania | Holotype is a compressed skull. | An early ray-finned fish. | ||
| :: |
Sarcopterygians
::data[format=table]
| Sarcopterygians of the Catskill Formation | Genus | Species | Presence | Material | Notes | Images |
|---|---|---|---|---|---|---|
| Apatorhynchus | A. opistheretmus | Apatorhynchus-type locality, Tioga County, Pennsylvania | Holotype is a partial skull, 1 specimen. | last1=Friedman | first1=Matt | last2=Daeschler |
| Densignathus | D. rowei | A stegocephalian tetrapodomorph. | ||||
| Eusthenodon | E. bourdoni | A tristichopterid tetrapodomorph. | [[File:Eusthenodon DB15 flipped.jpg | frameless]] | ||
| E. leganihanne | ||||||
| Hyneria | H. lindae | Red Hill Site, Clinton County, Pennsylvainia | Holotype is a disarticulated skull and 3D body fossil. | A tristichopterid tetrapodomorph. | [[File:Hyneria (cropped) 2.jpg | frameless]] |
| Hynerpeton | H. bassetti | last1=Daeschler | first1=Edward B. | last2=Shubin | ||
| Langlieria | L. radiata | A tristichopterid tetrapodomorph. Originally identified as Holoptychius. | [[File:Langleria.jpg | frameless]] | ||
| L. smalingi | Irish Valley Member | |||||
| Megalichthys | M. mullisoni | A megalichthyid tetrapodomorph. | [[File:Megalichthys hibberti (cropped).jpg | frameless]] | ||
| Sauripterus | S. taylori | Sherman Creek Locality, Lycoming County, Pennsylvainia | The Holotype is an articulated limb and 3 scales, there are 3 individuals. | A rhizodontid tetrapodomorph. | [[File:Sauripterus22DB.jpg | frameless]] |
| Soederberghia | S. groenlandica | Catskill Formation, Lycoming County, Pennsylvania | A rhynchodipterid lungfish. | |||
| Sterropterygion | S. brandei | An indeterminate osteolepiform tetrapodomorph. | ||||
| :: |
References
References
- (2018-12-15). "Depositional setting, taphonomy and geochronology of new fossil sites in the Catskill Formation (Upper Devonian) of north-central Pennsylvania, USA, including a new early tetrapod fossil". Palaeogeography, Palaeoclimatology, Palaeoecology.
- Rich, John Lyon. (1906). "Local Glaciation in the Catskill Mountains". The Journal of Geology.
- Titus, Robert. (1996). "The Catskills in the Ice Age". Purple Mountain Press.
- (2000). "''GIGANTOCHARINUS SZATMARYI,'' A NEW TRIGONOTARBID ARACHNID FROM THE LATE DEVONIAN OF NORTH AMERICA (CHELICERATA, ARACHNIDA, TRIGONOTARBIDA)". Journal of Paleontology.
- (2005). "New Flat-Backed Archipolypodan Millipedes from the Upper Devonian of North America". Journal of Paleontology.
- https://www.cambridge.org/core/services/aop-cambridge-core/content/view/8D4FFD7640A6FD82C65E1D4DD896855D/S0022336022000841a.pdf/eurypterids_from_the_price_formation_of_virginia_first_eurypterids_from_the_mississippian_of_north_america.pdf {{Bare URL PDF. (July 2025)
- (2011). "Mass Mortality of Juvenile Antiarchs ( Bothriolepis sp.) from the Catskill Formation (Upper Devonian, Famennian Stage), Tioga County, Pennsylvania". Proceedings of the Academy of Natural Sciences of Philadelphia.
- (2011-01-01). "Late Devonian paleontology and paleoenvironments at Red Hill and other fossil sites in the Catskill Formation of north-central Pennsylvania". Geological Society of America.
- (2013). "First Articulated Phyllolepid Placoderm from North America, with Comments on Phyllolepid Systematics". Proceedings of the Academy of Natural Sciences of Philadelphia.
- Daeschler, Edward B.. (2000). "An Early Actinopterygian Fish from the Catskill Formation (Late Devonian, Famennian) in Pennsylvania, U.S.A.". Proceedings of the Academy of Natural Sciences of Philadelphia.
- (2006). "Late Devonian (famennian) Lungfishes from the Catskill Formation of Pennsylvania, Usa". Palaeontology.
- Daeschler, E.B.. (2000). "Early tetrapod jaws from the Late Devonian of Pennsylvania, USA". Journal of Paleontology.
- (2021-05-04). "A new species of Eusthenodon (Sarcopterygii, Tristichopteridae) from the Upper Devonian (Famennian) of Pennsylvania, U.S.A., and a review of Eusthenodon taxonomy". Journal of Vertebrate Paleontology.
- (2022-11-25). "Second species of Eusthenodon (Tristichopteridae, Sarcopterygii) from the Upper Devonian (Famennian) Catskill Formation of Pennsylvania, U.S.A., and a review of global Eusthenodon occurrence". Journal of Vertebrate Paleontology.
- (29 July 1994). "A Devonian Tetrapod from North America". Science.
- (2019-05-09). "New material supports a description and taxonomic revision of Holoptychius ? radiatus (Sarcopterygii, Tristichopteridae) from the Upper Devonian Catskill Formation in Pennsylvania, USA". Proceedings of the Academy of Natural Sciences of Philadelphia.
- (2022-04-22). "Second species of Langlieria (Tristichopteridae, Sarcopterygii) from the Upper Devonian Catskill Formation of Pennsylvania, U.S.A., and a new phylogenetic consideration of Tristichopteridae". Proceedings of the Academy of Natural Sciences of Philadelphia.
- (2020-03-03). "A New Species of Megalichthys (Sarcopterygii, Megalichthyidae) from the Upper Devonian (Famennian) of Pennsylvania, U.S.A., and a Report on the Cosmine-Covered Osteolepiform Fossils of the Catskill Formation". Journal of Vertebrate Paleontology.
- 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.
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