Geologic Time Scale EON ERA PERIOD EPOCH Ma1 PLANTS ANIMALS GEOLOGY Modern Human civilization Himalayan Orogeny continues; 2 Holocene H Quaternary Q rifting continues elsewhere “entirely new” 0.01 An addition to the 18th C system Boreal plants migrate south into refugia; First humans; mass extinction with Ice Ages cover up to 30% of earth’s Pleistocene ` tundra becomes dominant in their place ice age surface “The Age of Man” “most new” 2.6 where land is ice-free Grasses become dominant; temperate First hominids, modern whales Arctic ice cap develops, earth much Pliocene ~ deciduous trees; boreal evergreen trees colder; Cascadian & Sierra { “more new” 5.3 Orogenies born” Grasses greatly diversify with the cooling Modern birds; horses, dogs, bears, Antarctica becomes permanently Tertiary3 Miocene ! “new climate; widespread forests dramatically So. American monkeys; first apes: frozen surrounded by a great “new life” “less new” T Neogene N reduce the amount of CO2 in the Sahelanthropus, Sivapithecus southern ocean; Tethys Sea closes “The Age of Grasses” 23.0 atmosphere forming modern Mediterranean CENOZOIC Third and final Grasses common, forests became Pigs, deer, cats, rhinos, tapirs Himalayan Orogeny: India collides th Oligocene@ 18 C division / temperate. Fabaceae increases. with Asia “little, few new” 33.9 “The Age of Mammals” of “The Age first two no Tropical forests, including the poles; Mammals abound; rodents & Alpine Orogeny longer used born” Eocene # “dawn of new” 55.8 warm primitive whales appear Rockies reach their maximum “old “old Angiosperms take on important First large mammals, primitive Australia separates from Antarctica Paleogene Paleocene $ ecological roles primates “old and new” 65.5 Angiosperms rapidly take over land Huge increase in dinosaurs; Laramide Orogeny; India separates Late niches; Moraceae, Platanaceae appear primitive marsupials; bees coevolve from Antarctica; meteor impact? Cretaceous K 99.6 w/ plants; major extinction at end “chalk” from English Betulaceae, Araliaceae, Magnoliaceae, Dinosaurs nearing peak including Sevier Orogeny ancestral Rockies; Channel Early Cornaceae, Fagaceae, Lauraceae, those with feathers; butterflies, Tethys Sea develops with rise in } 145.5 Palmae develop in localized populations snakes, ants, bees world ocean levels Late 161 First Angiosperms.Gymnosperms Dinosaurs & pterosaurs appear; first Ancestral Sierra Nevada mountains Jurassic J Aracarioxylon, Ferns, cycads, ginkgoes, “bird” Archaeopteryx appears; batholiths form Middle 176 rushes, conifers remain dominant ammonites abundant “middle life” Jura Mountains of France Early 201.6 make life appear” life make “ MESOZOIC Late 235 Rapid development of conifers & cycads First dinosaurs, mammals and Pangaea rifts apart forming the Triassic ^ after Permian extinction makes way. crocodiles. Turtles, ichthyosaurs. Atlantic Ocean in a quiet, semi-arid “The Age of Dinosaurs” of “The Age : From the German 3 part Middle 245 Liverworts, horsetails & club moss Mollusks are the dominant period with Pangaea about half of division decline while Cheiroleps conifer and the invertebrate. True flies earth’s surface Early 251 seed fern Glossopteris dominate Late 260 Gymnosperms abundant; liverworts, Amphibians & reptiles dominant; Alleghanian Orogeny and others Permian P horsetails & club moss dominant. stoneflies, true bugs, beetles, form Pangaea; much glaciation & Perm region of Russia Middle 271 Phytoplankton & plants oxygenate caddisflies. Massive extinction: 50% volcanic activity leads to massive “The Age of Amphibians” atmosphere to near modern levels of families, 95% of marine species extinction at the end of the period. Phanerozoic Phanerozoic Early 299 * Vast coal forests of scale trees, ferns, First reptiles; First winged insects- Great swamps and lowlands in Pennsylvanian 318 club trees, giant horsetails mayflies & cockroaches Laurasia Carboniferous C Pteridospermatophyta (seed ferns) <2 m Amphibious sea scorpions, Vast limestone deposits formed in From the abundance of tall; vast coal-forming swamps; first large rhizodonts, crinoids, blastoids; passive margins of Laurasia and coal Mississippian M trees corals, bryozoan, brachiopods Gondwana during interorogenic 359 common; sharks common & diverse calm Late 385 Psilophyta Psilophyton and Rhynia, Fish become abundant and diverse. Acadian Orogeny; much glaciation; | Devonian D become abundant and diverse; first First amphibians, sharks, bony fish meteor impact? C C Middle 398 clubmosses, horsetails and ferns; first appear Devonshire, UK Early 416 primitive gymnosperm Archaeopteris “old life” Late 423 First vascular plants such as the First jawed fish, primitive High sea level with calm, shallow Psilophyta (plants that lack leaves and centipedes; brachiopods, corals seas during interorogenic calm with Silurian S Middle 428 Ancient British tribe roots but have a vascular system) deserts leading to vast salt deposits PALEOZOI Early 444 Cooksonia appear on land Late 461 Primitive plants something like liverworts First corals, primitive fish, Taconic Orogeny; High sea level appear on land with spores gathered in a bryozoans, gastropods, bivalves, followed by global cooling and Ordovician O Middle 472 Ancient British tribe case; fungi; marine algae proliferate echinoids glaciation; much volcanism. Early 488 Furongian4 501 Marine algae “Cambrian Explosion” of life where Rodinia breaks up, sediments Land devoid of plants all existent phyla develop. Marine collect, mild climate world-wide in an Cambrian _ 4 Cambria, Roman name Series 3 510 Atmospheric CO2 content ~20-35 times invertebrates dominate such as interorogenic calm for Wales Series 24 521 present-day Trilobites; first vertebrates, earliest “The Age of Trilobites” fish Terreneuvian4 542 EON ERA Land devoid of plants Multi-cellular animals dominant. Grenville Orogeny forms Rodinia, Oxygen begins to increase in the the first supercontinent; shallow Neoproterozoic Z 1000 atmosphere. Stromatolites. continental shelves develop < “PRE- Proterozoic Mesoproteozoic Y 1600 CAMBRIAN” “Before earth life” Paleoproterozoic X 2500 = “before the Cambrian” Neoarchean W 2800 Simple, single cell life appears in Heat flow 3x more than today the Eoarchean from microfossil providing energy for vigorous plate Mesoarchean V This is an informal but Archean A 3200 evidence. movement of small felsic well entrenched name “arkhaios”, ancient Paleoarchean U 3600 No oxygen in the atmosphere. protocontinents moving on a mafic for the “super eon” convection currents; deep oceans at before the Eoarchean 3850 end and normal surface temperature Phanerozoic Imbrian & Nectarian The first life forms and self-replicating RNA molecules may have evolved on earth Napier Orogeny in Antarctica, 4000 Hadean sometimes used; adopted around 4000 Ma during this eon ma; oldest rock-orthogneiss 4030 “hades”, underworld from Lunar geology 4600 ma; oldest mineral-zircon 4406 ma © 2010 L. Scott Ranger, www.scottranger.com, who is responsible for any and all errors. Geologic time adopted from 2009 Geologic Time Scale, The Geological Society of America. Plant, animal and geologic events adapted from a myriad of sources. Geologic time is a work in progress, always changing with new evidence. 1 Ma = millions of years ago from the beginning (bottom) of the time period. 2 Letters and ligatures after the name are standard abbreviations. 3 Entrenched Western name no longer in international use. 4 Names not yet adopted by the International Commission on Stratigraphy (ICS) that established names and abbreviations. .