| Start | End | Erathem | Sub-Era | System | Sub-Sy | Series | Sub-Ser | Stage |
| Age | Age | them: | stem | ies |
| (Million Years) |
| 321 | 319 | PP | Palaeozoic | UP | Upper Palaeozoic | C | Carboniferous | CU | Silesian(U.Carbonifer.) | CN | Namurian | AN | Namurian A | CO | Alportian |
| 323 | 321 | CH | Chokierian |
| 325 | 323 | CG | Arnsbergian |
| 326 | 325 | CE | Pendleian |
| 360 | 326 | CL | Dinantian(L.Carbonif.) | CL | Dinantian(L.Carbonif.) |
| 355 | 326 | CV | Visean |
| 332 | 326 | CX | Brigantian |
| 338 | 332 | AS | Asbian |
| 344 | 338 | CQ | Holkerian |
| 349 | 344 | CJ | Arundian |
| 355 | 349 | CI | Chadian |
| 360 | 355 | CT | Tournaisian |
| 360 | 355 | CF | Courceyan |
| 400 | 360 | D | Devonian ORS |
| 400 | 360 | DO | Old Red Sandstone |
| 375 | 360 | DU | Upper Devonian |
| 369 | 360 | DA | Famennian |
| 364 | 360 | DN | Strunian |
| 375 | 360 | DF | Farlovian |
| 375 | 369 | DR | Frasnian |
| 385 | 375 | DM | Middle Devonian |
| 385 | 375 | DC | Orcadian |
| 380 | 375 | DV | Givetian |
| 385 | 380 | DI | Eifelian |
| 400 | 385 | DL | Lower Devonian |
| 393 | 385 | DB | Breconian |
| 390 | 385 | DE | Emsian |
| 395 | 390 | DS | Siegenian |
| 400 | 393 | DT | Dittonian |
| 400 | 395 | DG | Gedinnian |
| 418 | 400 | S | Silurian |
| 404 | 400 | SO | Downtonian |
| 408 | 404 | SU | Ludlow |
| 412 | 408 | SW | Wenlock |
| 418 | 412 | SL | Llandovery |
| 530 | 418 | PB | Lower Palaeozoic |
| 475 | 418 | O | Ordovician |
| 425 | 418 | OA | Ashgill |
| 438 | 425 | OC | Caradoc |
| 455 | 438 | OD | Llandeilo |
| 470 | 455 | OV | Llanvirn |
| 475 | 470 | OR | Arenig |
| 530 | 475 | E | Cambrian |
| 505 | 475 | EU | Upper Cambrian |
| 495 | 475 | ET | Tremadoc |
| 505 | 495 | EM | Merioneth |
| 515 | 505 | EB | Middle Cambrian |
| 515 | 505 | ED | St Davids |
| 530 | 515 | EL | Lower Cambrian |
| 530 | 515 | EC | Comley |
| 530 | 515 | EF | Caerfaian |
| 4600 | 530 | ZZ | Precambrian |
| 700 | 530 | … | DD | Dalradian |
| 1100 | 700 | MD | Moinian |
| 1100 | 700 | TO | Torridonian |
| 850 | 800 | ZC | Charnian |
| 2700 | 1100 | LE | Lewisian |
| 2700 | 1650 | LX | Laxfordian |
| 1650 | 1100 | LN | Inverian |
| 5000 | 4999 | UD | Undifferentiated |
| 5000 | 4999 | UK | Unknown |
| Page 3 of 4 | 07/07/2004 |