Formation · Devonian
Mahantango Formation
Middle Devonian unit, Pennsylvania · New York · Maryland · West Virginia
The Mahantango Formation and the wider Hamilton Group of Pennsylvania and New York are Middle Devonian shales that supply Eldredgeops rana trilobites, the large Dipleura, Greenops, Mucrospirifer and Spinocyrtia brachiopods and Heliophyllum horn corals to eastern collectors. Penn Dixie in Hamburg, New York, and the Montour Preserve pit in Pennsylvania are legal, family-friendly sites. Trilobites from the shale are often flattened; three-dimensional enrolled specimens come from calcareous concretions and cost more.
| Country | United States |
|---|---|
| Region | Pennsylvania, New York, Maryland, West Virginia |
| Age | Givetian, Middle Devonian |
| Age range | ~388–383 Ma |
| Group | Hamilton Group |
| Macrostrat rank | Fm· Macrostrat |
| Macrostrat age | 388–382 Ma· Macrostrat |
| Lithology | shale, sandstone, claystone, siltstone· Macrostrat |
| Environment | inferred marine· Macrostrat |
| Macrostrat columns | 2 column(s) sampled from 7 unit(s)· Macrostrat |
| Members (Macrostrat) | Dalmatia, Fisher Ridge, Sherman Ridge, Tully· Macrostrat |
| PBDB collections | 71 collections, 754 occurrences· Paleobiology Database |
Collecting and legality
Pennsylvania road cuts (Swatara Gap, Montour Preserve) and New York's Penn Dixie Fossil Park (pay-to-dig, keep what you find) are the usual sources; PennDOT rights-of-way are technically restricted, and the Montour Preserve fossil pit is free with a hand-tool rule. Private quarries require permission.
Lithology and setting
Dark grey silty shale and siltstone of the Hamilton Group, deposited in the Appalachian foreland basin.
Commonly recorded taxa (PBDB)
Genera most often recorded from this unit in the Paleobiology Database (first 200 occurrences): Athyris (4), Spirifer (4), Tropidoleptus (4), Actinopteria (3), Bembexia (3), Camarotoechia (3), Cornellites (3), Crenistriella (3), Crinoidea (3), Cystoporata (3), Delthyris (3), Devonochonetes (3), Favosites (3), Fenestella (3), Goniophora (3).
Source: Paleobiology Database
Elsewhere
- Macrostrat: 63754
- macrostratConcept: 2597
- PBDB: strata:Mahantango
- Wikidata: Q13405995
- Macrostrat stratigraphic name
- PBDB occurrences for this unit
- Wikipedia: Mahantango Formation
- Mindat: Mahantango Formation
Cite this article
Stratum Study. "Mahantango Formation" (Formation). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/formations/mahantango-formation. Accessed 2026-09-20.
@misc{stratum-mahantango-formation,
title = {Mahantango Formation},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/formations/mahantango-formation}},
year = {2026},
note = {Formation article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, macrostrat, pbdb, wikidata, commons. Accessed 2026-09-20.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.