GSA GEOLOGIC TIME SCALE MESOZOIC OLIGOCENE C9 11 13 19 C18 20 C20 45 21 50 C21 22 C22 23 140 28.1 150 RUPELIAN 37.8 BARTONIAN 41.2 LUTETIAN 180 190 47.8 YPRESIAN C23 26 C26 60 27 C27 28 C28 65 29 C29 30 C30 PALEOCENE C25 300 ALBIAN 113 320 APTIAN EARLY BARREMIAN HAUTERIVIAN 126 131 134 139 LATE MIDDLE KIMMERIDGIAN OXFORDIAN CALLOVIAN BATHONIAN BAJOCIAN AALENIAN 152 380 157 164 166 168 170 174 400 56.0 220 THANETIAN SELANDIAN 59.2 61.6 230 240 DANIAN 66.0 250 PERMIAN Cisuralian PLIENSBACHIAN 420 440 191 SINEMURIAN HETTANGIAN 199 201 460 209 480 LATE CHRON. ERA PERIOD 228 LADINIAN ANISIAN EARLY OLENEKIAN INDUAN MIDDLE MOSCOVIAN EARLY BASHKIRIAN LATE SERPUKHOVIAN MIDDLE VISEAN EARLY TOURNAISIAN LATE 237 520 241 247 250 252 540 1250 315 323 1500 331 347 MIDDLE 1750 359 2000 372 GIVETIAN EIFELIAN 383 388 393 PRIDOLI LUDLOW WENLOCK LLANDOVERY LATE MIDDLE EARLY Epoch 3 Epoch 2 TERRENEUVIAN LUDFORDIAN GORSTIAN HOMERIAN SHEINWOODIAN TELYCHIAN AERONIAN RHUDDANIAN HIRNANTIAN KATIAN SANDBIAN DARRIWILIAN DAPINGIAN FLOIAN TREMADOCIAN AGE 10 JIANGSHANIAN PAIBIAN GUZHANGIAN DRUMIAN AGE 5 AGE 4 AGE 3 AGE 2 408 411 419 423 426 427 430 433 439 441 444 445 453 458 467 470 635 CRYOGENIAN 850 1000 1200 MESOPROTEROZOIC ECTASIAN 1400 CALYMMIAN 1600 STATHERIAN 1800 OROSIRIAN PALEOPROTEROZOIC 2050 RHYACIAN 2250 2300 SIDERIAN 2500 2500 NEOARCHEAN 2750 2800 3000 3250 478 485 490 494 497 501 505 509 514 541 STENIAN EMSIAN PRAGIAN BDY. AGES (Ma) TONIAN 1000 290 296 299 304 307 NEOPROTEROZOIC 750 FRASNIAN FURONGIAN CARNIAN 260 265 269 272 279 ARTINSKIAN SAKMARIAN ASSELIAN GZHELIAN KASIMOVIAN EDIACARAN 252 254 FAMENNIAN NORIAN 500 MIDDLE CHANGHSINGIAN WUCHIAPINGIAN CAPITANIAN WORDIAN ROADIAN KUNGURIAN LOCHKOVIAN 183 EARLY LATE EARLY TOARCIAN 200 210 Guadalupian 360 145 TITHONIAN M22 340 RHAETIAN C24 25 280 93.9 100 BERRIASIAN 160 170 83.6 86.3 89.8 CENOMANIAN VALANGINIAN M25 24 55 TURONIAN M12 M14 M16 M18 M20 M29 PRIABONIAN C17 C19 130 M0r M1 M3 M5 SANTONIAN CONIACIAN M10 33.9 EOCENE 18 120 CHATTIAN C13 15 C15 16 C16 17 40 C12 PALEOGENE 35 C11 HIST BURDIGALIAN 23.0 10 C10 12 110 AQUITANIAN 7 C7 7A C7A 8 C8 34 C34 EON PROTEROZOIC 16.0 6C C6C 30 100 LANGHIAN 20.4 6B C6B 9 13.8 C6 6A C6A 25 11.6 AGE (Ma) 3500 ARCHEAN 20 5E 6 C5E SERRAVALLIAN 90 CAMPANIAN LATE PENNSYLVANIAN 5B C5B 5C C5C 5D C5D TORTONIAN 260 MISSISSIPPIAN C5A 33 C33 Lopingian 72.1 CARBONIFEROUS 15 C5 MAASTRICHTIAN 32 C32 80 AGE PRECAMBRIAN PICKS (Ma) 66.0 30 C30 31 C31 7.2 AGE PERIOD EPOCH (Ma) DEVONIAN 5A C4A MIOCENE 5 NEOGENE 4A 10 C4 5.3 70 AGE PALEOZOIC PICKS (Ma) ORDOVICIAN SILURIAN MESSINIAN 3A C3A 4 PIACENZIAN ZANCLEAN 0.01 1.8 2.6 3.6 CRETACEOUS 5 PLIOCENE C3 CALABRIAN GELASIAN PERIOD EPOCH JURASSIC HOLOCENE QUATERNARY PLEISTOCENE* 2A C2A 3 AGE MAGNETIC POLARITY TRIASSIC C1 C2 EPOCH AGE (Ma) RAPID POLARITY CHANGES 1 2 PERIOD PICKS (Ma) ANOM. CHRON. HIST. ANOM. MAGNETIC POLARITY CAMBRIAN CENOZOIC AGE (Ma) v. 4.0 MESOARCHEAN 3200 PALEOARCHEAN 3600 3750 EOARCHEAN 521 529 FORTUNIAN 541 4000 4000 HADEAN *The Pleistocene is divided into four ages, but only two are shown here. What is shown as Calabrian is actually three ages—Calabrian from 1.8 to 0.78 Ma, Middle from 0.78 to 0.13 Ma, and Late from 0.13 to 0.01 Ma. Walker, J.D., Geissman, J.W., Bowring, S.A., and Babcock, L.E., compilers, 2012, Geologic Time Scale v. 4.0: Geological Society of America, doi: 10.1130/2012.CTS004R3C. ©2012 The Geological Society of America. The Cenozoic, Mesozoic, and Paleozoic are the Eras of the Phanerozoic Eon. Names of units and age boundaries follow the Gradstein et al. (2012) and Cohen et al. (2012) compilations. Age estimates and picks of boundaries are rounded to the nearest whole number (1 Ma) for the pre-Cenomanian, and rounded to one decimal place (100 ka) for the Cenomanian to Pleistocene interval. The numbered epochs and ages of the Cambrian are provisional. REFERENCES CITED Cohen, K.M., Finney, S., and Gibbard, P.L., 2012, International Chronostratigraphic Chart: International Commission on Stratigraphy, www.stratigraphy.org (last accessed May 2012). (Chart reproduced for the 34th International Geological Congress, Brisbane, Australia, 5–10 August 2012.) Gradstein, F.M, Ogg, J.G., Schmitz, M.D., et al., 2012, The Geologic Time Scale 2012: Boston, USA, Elsevier, DOI: 10.1016/B978-0-444-59425-9.00004-4.