List of mapped rock formations in Pennsylvania
# List of mapped rock formations in Pennsylvania

The following is a list of the mapped bedrock units in Pennsylvania. The rocks are listed in stratigraphic order.

| System | Group name | Formation name | Member name | Map symbol |
| - | - | - | - | - |
| Triassic | Newark Group | Passaic Formation | | Trp |
| Triassic | Newark Group | Lockatong Formation | | Trl |
| Triassic | Newark Group | Stockton Formation | | Trs |
| Permian | Dunkard Group | Greene Formation | | Pg |
| Permian | Dunkard Group | Washington Formation | | Pw |
| Pennsylvanian | Conemaugh Group | Casselman Formation | | φcc |
| Pennsylvanian | Conemaugh Group | Glenshaw Formation | | φcg |
| Pennsylvanian | | Allegheny Formation | | φa |
| Pennsylvanian | | Llewellyn Formation | | φl |
| Pennsylvanian | | Pottsville Formation | | φp |
| Mississippian | | Mauch Chunk Formation | | Mmc |
| Mississippian | | Pocono Formation (Burgoon Formation) | | Mp (Mb) |
| Mississippian/Devonian | | Spechty Kopf Formation | | |
| Mississippian/Devonian | | Rockwell Formation | | |
| Mississippian/Devonian | | Huntley Mountain Formation | | |
| Devonian | | Catskill Formation | | Dck |
| Devonian | | Brallier Formation | | Db |
| Devonian | | Harrell Formation | | Dh |
| Devonian | Hamilton Group | Mahantango Formation | | Dmh |
| Devonian | Hamilton Group | Marcellus Formation | | Dm |
| Devonian | | Onondaga Formation | | Do |
| Devonian | | Old Port Formation | | Dop |
| Devonian | | Old Port Formation | Ridgeley Member | Dr |
| Devonian/Silurian | | Keyser Formation | | DSk |
| Silurian | | Tonoloway Formation | | Sto |
| Silurian | | Wills Creek Formation | | Swc |
| Silurian | | Bloomsburg Formation | | Sb |
| Silurian | | Mifflintown Formation | | Sm |
| Silurian | Clinton Group | Keefer Formation | | Sk |
| Silurian | Clinton Group | Rose Hill Formation | | Srh |
| Silurian | | Tuscarora Formation | | St |
| Silurian | | Shawangunk Formation | | Ss |
| Ordovician | | Juniata Formation | | Oj |
| Ordovician | | Bald Eagle Formation | | Obe |
| Ordovician | | Reedsville Formation | | Or |
| Ordovician | | Martinsburg Formation | | Om |
| Ordovician | Trenton Group | Coburn Formation | | |
| Ordovician | Trenton Group | Salona Formation | | |
| Ordovician | Trenton Group | Nealmont Formation | | |
| Ordovician | | Benner Formation | | Om |
| Ordovician | | Bellefonte Formation | | Obf |
| Ordovician | | Axeman Formation | | Oa |
| Ordovician | | Nittany Formation | | On |
| Ordovician | | Stonehenge/Larke Formation | | Osl |
| Cambrian | | Warrior Formation | | Cw |
| Cambrian | | Chickies Formation | | Cch |
| Cambrian/Ediacaran | | Wissahickon Formation | | CZw |
| Mesoproterozoic Era | | Baltimore Gneiss | | Ybg |

Note: Some of the Formations are laterally equivalent in age. They are listed in order from West to East in this case.

