| water |
| C - Cambrian |
| Ce - Cambrian eugeosynclinal |
| Cq - Basal Lower Cambrian clastic rocks |
|
| Cv - Cambrian volcanics |
| D - Devonian |
| D1 - Lower Devonian |
|
| D2 - Middle Devonian |
| D2c - Middle Devonian continental |
| D3 - Upper Devonian |
|
| D3c - Upper Devonian continental |
| DS - Devonian and Silurian |
| Jc - Jurassic continental |
| lK - Lower Cretaceous |
| M - Mississippian |
| M1 - Osagean and Kinderhookian Series |
| M2 - Meramecian Series |
|
| M3 - Chesterian Series |
| O - Ordovician |
| O1 - Lower Ordovician (Canadian) |
|
| O2 - Middle Ordovician (Mohawkian) |
| O3 - Upper Ordovician (Cincinnatian) |
|
| OC - Lower Ordovician and Cambrian carbonate rocks |
|
| Oe - Ordovician eugeosynclinal |
|
| P1 - Wolfcampian Series |
| PP - Pennsylvanian |
| PP1 - Atokan and Morrowan Series |
| PP2 - Des Moinesian Series |
| PP3 - Missourian Series |
| PP4 - Virgilian Series |
| Pzg1 - Lower Paleozoic granitic rocks |
|
| Pzmi - Paleozoic mafic intrusives |
| Qh - Holocene |
| Qp - Pleistocene |
| S - Silurian |
| S1 - Lower Silurian (Alexandrian) |
|
| S2 - Middle Silurian (Niagaran) |
|
| S3 - Upper Silurian (Cayugan) |
| Te - Eocene |
|
| Te1 - Eocene Wilcox Group |
| Te2 - Eocene Claiborne Group |
| Te3 - Eocene Jackson Group |
| Tm - Miocene |
| Tr - Triassic |
| Tri - Triassic mafic intrusives |
| Trv - Triassic Newark Group mafic lava interbedded |
| Tx - Paleocene |
| uK - Upper Cretaceous |
|
| uK4 - Navarro Group |
| um - Ultramafic rocks |
| Wg - W granitic rocks |
|
| Wv - W volcanic rocks |
| X - X metasedimentary rocks |
|
| Xg - X granitic rocks |
|
| Xv - X volcanic rocks |
| Y - Y sedimentary rocks |
|
| Ya - Anorthosite |
|
| Ygn - Orthogneiss |
| Yg2 - Younger Y granitic rocks |
|
| Ym - Paragneiss and schist |
| Ys - Syenite |
|
| Yv - Y volcanic rocks |
|
| Z - Z sedimentary rocks |
| Zv - Z volcanic rocks |
