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 | Cassleman 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 | Mp | ||
| 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.