<P> The content of the table is based on the current official geologic time scale of the International Commission on Stratigraphy, with the epoch names altered to the early / late format from lower / upper as recommended by the ICS when dealing with chronostratigraphy . </P> <P> A service providing a Resource Description Framework / Web Ontology Language representation of the timescale is available through the Commission for the Management and Application of Geoscience Information GeoSciML project as a service and at a SPARQL end - point . </P> <Table> <Tr> <Th> (hide) Supereon </Th> <Th> Eon </Th> <Th> Era </Th> <Th> Period </Th> <Th> Epoch </Th> <Th> Age </Th> <Th> Major events </Th> <Th> Start, million years ago </Th> </Tr> <Tr> <Td> n / a </Td> <Td> Phanerozoic </Td> <Td> Cenozoic </Td> <Td> Quaternary </Td> <Td> Holocene </Td> <Td> <P> chrons: Subatlantic Subboreal Atlantic Boreal Preboreal </P> </Td> <Td> Quaternary Ice Age recedes, and the current interglacial begins . Sahara forms from savannah . Rise of human civilization, beginning of agriculture . Stone Age cultures give way to Bronze Age (3300 BC) and Iron Age (1200 BC), giving rise to many pre-historic cultures throughout the world . Little Ice Age (stadial) causes brief cooling in Northern Hemisphere from 1400 to 1850 . Following the Industrial Revolution, atmospheric CO levels rise from around 280 parts per million volume (ppmv) to the current level of 400 ppmv . </Td> <Td> 0.0117 </Td> </Tr> <Tr> <Td> Pleistocene </Td> <Td> Late (locally Tarantian Tyrrhenian Eemian Sangamonian) </Td> <Td> Flourishing and then extinction of Pleistocene megafauna . Evolution of anatomically modern humans . Quaternary Ice Age continues with glaciations and interstadials (and the accompanying fluctuations from 100 to 300 ppmv in atmospheric CO levels), further intensification of Icehouse Earth conditions, roughly 1.6 Ma . Last glacial maximum (30000 years ago), last glacial period (18000--15000 years ago). Dawn of human stone - age cultures, with increasing technical complexity relative to previous ice age cultures, such as engravings and clay statues (e.g. Venus of Lespugue), particularly in the Mediterranean and Europe . Lake Toba supervolcano erupts 75000 years before present, causing a volcanic winter that possibly pushes humanity to the brink of extinction . Pleistocene ends with Oldest Dryas, Older Dryas / Allerød and Younger Dryas climate events, with Younger Dryas forming the boundary with the Holocene . </Td> <Td> 0.126 </Td> </Tr> <Tr> <Td> Middle (formerly Ionian) </Td> <Td> 0.781 </Td> </Tr> <Tr> <Td> Calabrian </Td> <Td> 1.8 </Td> </Tr> <Tr> <Td> Gelasian </Td> <Td> 2.58 </Td> </Tr> <Tr> <Td> Neogene </Td> <Td> Pliocene </Td> <Td> Piacenzian </Td> <Td> Intensification of present Icehouse conditions, present (Quaternary) ice age begins roughly 2.58 Ma; cool and dry climate . Australopithecines, many of the existing genera of mammals, and recent mollusks appear . Homo habilis appears . </Td> <Td> 3.6 </Td> </Tr> <Tr> <Td> Zanclean </Td> <Td> 5.333 </Td> </Tr> <Tr> <Td> Miocene </Td> <Td> Messinian </Td> <Td> Moderate Icehouse climate, punctuated by ice ages; Orogeny in Northern Hemisphere . Modern mammal and bird families become recognizable . Horses and mastodons diverse . Grasses become ubiquitous . First apes appear (for reference see the article: "Sahelanthropus tchadensis"). Kaikoura Orogeny forms Southern Alps in New Zealand, continues today . Orogeny of the Alps in Europe slows, but continues to this day . Carpathian orogeny forms Carpathian Mountains in Central and Eastern Europe . Hellenic orogeny in Greece and Aegean Sea slows, but continues to this day . Middle Miocene Disruption occurs . Widespread forests slowly draw in massive amounts of CO, gradually lowering the level of atmospheric CO from 650 ppmv down to around 100 ppmv . </Td> <Td> 7.246 </Td> </Tr> <Tr> <Td> Tortonian </Td> <Td> 11.63 </Td> </Tr> <Tr> <Td> Serravallian </Td> <Td> 13.82 </Td> </Tr> <Tr> <Td> Langhian </Td> <Td> 15.97 </Td> </Tr> <Tr> <Td> Burdigalian </Td> <Td> 20.44 </Td> </Tr> <Tr> <Td> Aquitanian </Td> <Td> 23.03 </Td> </Tr> <Tr> <Td> Paleogene </Td> <Td> Oligocene </Td> <Td> Chattian </Td> <Td> Warm but cooling climate, moving towards Icehouse; Rapid evolution and diversification of fauna, especially mammals . Major evolution and dispersal of modern types of flowering plants </Td> <Td> 28.1 </Td> </Tr> <Tr> <Td> Rupelian </Td> <Td> 33.9 </Td> </Tr> <Tr> <Td> Eocene </Td> <Td> Priabonian </Td> <Td> Moderate, cooling climate . Archaic mammals (e.g. Creodonts, Condylarths, Uintatheres, etc .) flourish and continue to develop during the epoch . Appearance of several "modern" mammal families . Primitive whales diversify . First grasses . Reglaciation of Antarctica and formation of its ice cap; Azolla event triggers ice age, and the Icehouse Earth climate that would follow it to this day, from the settlement and decay of seafloor algae drawing in massive amounts of atmospheric carbon dioxide, lowering it from 3800 ppmv down to 650 ppmv . End of Laramide and Sevier Orogenies of the Rocky Mountains in North America . Orogeny of the Alps in Europe begins . Hellenic Orogeny begins in Greece and Aegean Sea . </Td> <Td> 37.8 </Td> </Tr> <Tr> <Td> Bartonian </Td> <Td> 41.2 </Td> </Tr> <Tr> <Td> Lutetian </Td> <Td> 47.8 </Td> </Tr> <Tr> <Td> Ypresian </Td> <Td> 56 </Td> </Tr> <Tr> <Td> Paleocene </Td> <Td> Thanetian </Td> <Td> Climate tropical . Modern plants appear; Mammals diversify into a number of primitive lineages following the extinction of the dinosaurs . First large mammals (up to bear or small hippo size). Alpine orogeny in Europe and Asia begins . Indian Subcontinent collides with Asia 55 Ma, Himalayan Orogeny starts between 52 and 48 Ma . </Td> <Td> 59.2 </Td> </Tr> <Tr> <Td> Selandian </Td> <Td> 61.6 </Td> </Tr> <Tr> <Td> Danian </Td> <Td> 66 </Td> </Tr> <Tr> <Td> Mesozoic </Td> <Td> Cretaceous </Td> <Td> Late </Td> <Td> Maastrichtian </Td> <Td> Flowering plants proliferate, along with new types of insects . More modern teleost fish begin to appear . Ammonoidea, belemnites, rudist bivalves, echinoids and sponges all common . Many new types of dinosaurs (e.g. Tyrannosaurs, Titanosaurs, duck bills, and horned dinosaurs) evolve on land, as do Eusuchia (modern crocodilians); and mosasaurs and modern sharks appear in the sea . Primitive birds gradually replace pterosaurs . Monotremes, marsupials and placental mammals appear . Break up of Gondwana . Beginning of Laramide and Sevier Orogenies of the Rocky Mountains . atmospheric CO close to present - day levels . </Td> <Td> 72.1 ± 0.2 </Td> </Tr> <Tr> <Td> Campanian </Td> <Td> 83.6 ± 0.2 </Td> </Tr> <Tr> <Td> Santonian </Td> <Td> 86.3 ± 0.5 </Td> </Tr> <Tr> <Td> Coniacian </Td> <Td> 89.8 ± 0.3 </Td> </Tr> <Tr> <Td> Turonian </Td> <Td> 93.9 </Td> </Tr> <Tr> <Td> Cenomanian </Td> <Td> 100.5 </Td> </Tr> <Tr> <Td> Early </Td> <Td> Albian </Td> <Td> ~ 113 </Td> </Tr> <Tr> <Td> Aptian </Td> <Td> ~ 125 </Td> </Tr> <Tr> <Td> Barremian </Td> <Td> ~ 129.4 </Td> </Tr> <Tr> <Td> Hauterivian </Td> <Td> ~ 132.9 </Td> </Tr> <Tr> <Td> Valanginian </Td> <Td> ~ 139.8 </Td> </Tr> <Tr> <Td> Berriasian </Td> <Td> ~ 145 </Td> </Tr> <Tr> <Td> Jurassic </Td> <Td> Late </Td> <Td> Tithonian </Td> <Td> Gymnosperms (especially conifers, Bennettitales and cycads) and ferns common . Many types of dinosaurs, such as sauropods, carnosaurs, and stegosaurs . Mammals common but small . First birds and lizards . Ichthyosaurs and plesiosaurs diverse . Bivalves, Ammonites and belemnites abundant . Sea urchins very common, along with crinoids, starfish, sponges, and terebratulid and rhynchonellid brachiopods . Breakup of Pangaea into Gondwana and Laurasia . Nevadan orogeny in North America . Rangitata and Cimmerian Orogenies taper off . Atmospheric CO levels 4--5 times the present day levels (1200--1500 ppmv, compared to today's 385 ppmv). </Td> <Td> 152.1 ± 0.9 </Td> </Tr> <Tr> <Td> Kimmeridgian </Td> <Td> 157.3 ± 1.0 </Td> </Tr> <Tr> <Td> Oxfordian </Td> <Td> 163.5 ± 1.0 </Td> </Tr> <Tr> <Td> Middle </Td> <Td> Callovian </Td> <Td> 166.1 ± 1.2 </Td> </Tr> <Tr> <Td> Bathonian </Td> <Td> 168.3 ± 1.3 </Td> </Tr> <Tr> <Td> Bajocian </Td> <Td> 170.3 ± 1.4 </Td> </Tr> <Tr> <Td> Aalenian </Td> <Td> 174.1 ± 1.0 </Td> </Tr> <Tr> <Td> Early </Td> <Td> Toarcian </Td> <Td> 182.7 ± 0.7 </Td> </Tr> <Tr> <Td> Pliensbachian </Td> <Td> 190.8 ± 1.0 </Td> </Tr> <Tr> <Td> Sinemurian </Td> <Td> 199.3 ± 0.3 </Td> </Tr> <Tr> <Td> Hettangian </Td> <Td> 201.3 ± 0.2 </Td> </Tr> <Tr> <Td> Triassic </Td> <Td> Late </Td> <Td> Rhaetian </Td> <Td> Archosaurs dominant on land as dinosaurs, in the oceans as Ichthyosaurs and nothosaurs, and in the air as pterosaurs . Cynodonts become smaller and more mammal - like, while first mammals and crocodilia appear . Dicroidium flora common on land . Many large aquatic temnospondyl amphibians . Ceratitic ammonoids extremely common . Modern corals and teleost fish appear, as do many modern insect clades . Andean Orogeny in South America . Cimmerian Orogeny in Asia . Rangitata Orogeny begins in New Zealand . Hunter - Bowen Orogeny in Northern Australia, Queensland and New South Wales ends, (c. 260--225 Ma) </Td> <Td> ~ 208.5 </Td> </Tr> <Tr> <Td> Norian </Td> <Td> ~ 227 </Td> </Tr> <Tr> <Td> Carnian </Td> <Td> ~ 237 </Td> </Tr> <Tr> <Td> Middle </Td> <Td> Ladinian </Td> <Td> ~ 242 </Td> </Tr> <Tr> <Td> Anisian </Td> <Td> 247.2 </Td> </Tr> <Tr> <Td> Early </Td> <Td> Olenekian </Td> <Td> 251.2 </Td> </Tr> <Tr> <Td> Induan </Td> <Td> 251.902 ± 0.06 </Td> </Tr> <Tr> <Td> Paleozoic </Td> <Td> Permian </Td> <Td> Lopingian </Td> <Td> Changhsingian </Td> <Td> Landmasses unite into supercontinent Pangaea, creating the Appalachians . End of Permo - Carboniferous glaciation . Synapsid reptiles (pelycosaurs and therapsids) become plentiful, while parareptiles and temnospondyl amphibians remain common . In the mid-Permian, coal - age flora are replaced by cone - bearing gymnosperms (the first true seed plants) and by the first true mosses . Beetles and flies evolve . Marine life flourishes in warm shallow reefs; productid and spiriferid brachiopods, bivalves, forams, and ammonoids all abundant . Permian - Triassic extinction event occurs 251 Ma: 95% of life on Earth becomes extinct, including all trilobites, graptolites, and blastoids . Ouachita and Innuitian orogenies in North America . Uralian orogeny in Europe / Asia tapers off . Altaid orogeny in Asia . Hunter - Bowen Orogeny on Australian continent begins (c. 260--225 Ma), forming the MacDonnell Ranges . </Td> <Td> 254.14 ± 0.07 </Td> </Tr> <Tr> <Td> Wuchiapingian </Td> <Td> 259.1 ± 0.4 </Td> </Tr> <Tr> <Td> Guadalupian </Td> <Td> Capitanian </Td> <Td> 265.1 ± 0.4 </Td> </Tr> <Tr> <Td> Wordian </Td> <Td> 268.8 ± 0.5 </Td> </Tr> <Tr> <Td> Roadian </Td> <Td> 272.95 ± 0.5 </Td> </Tr> <Tr> <Td> Cisuralian </Td> <Td> Kungurian </Td> <Td> 283.5 ± 0.6 </Td> </Tr> <Tr> <Td> Artinskian </Td> <Td> 290.1 ± 0.26 </Td> </Tr> <Tr> <Td> Sakmarian </Td> <Td> 295 ± 0.18 </Td> </Tr> <Tr> <Td> Asselian </Td> <Td> 298.9 ± 0.15 </Td> </Tr> <Tr> <Td> Carbon - iferous </Td> <Td> Pennsylvanian </Td> <Td> Gzhelian </Td> <Td> Winged insects radiate suddenly; some (esp . Protodonata and Palaeodictyoptera) are quite large . Amphibians common and diverse . First reptiles and coal forests (scale trees, ferns, club trees, giant horsetails, Cordaites, etc .). Highest - ever atmospheric oxygen levels . Goniatites, brachiopods, bryozoa, bivalves, and corals plentiful in the seas and oceans . Testate forams proliferate . Uralian orogeny in Europe and Asia . Variscan orogeny occurs towards middle and late Mississippian Periods . </Td> <Td> 303.7 ± 0.1 </Td> </Tr> <Tr> <Td> Kasimovian </Td> <Td> 307 ± 0.1 </Td> </Tr> <Tr> <Td> Moscovian </Td> <Td> 315.2 ± 0.2 </Td> </Tr> <Tr> <Td> Bashkirian </Td> <Td> 323.2 ± 0.4 </Td> </Tr> <Tr> <Td> Mississippian </Td> <Td> Serpukhovian </Td> <Td> Large primitive trees, first land vertebrates, and amphibious sea - scorpions live amid coal - forming coastal swamps . Lobe - finned rhizodonts are dominant big fresh - water predators . In the oceans, early sharks are common and quite diverse; echinoderms (especially crinoids and blastoids) abundant . Corals, bryozoa, goniatites and brachiopods (Productida, Spiriferida, etc .) very common, but trilobites and nautiloids decline . Glaciation in East Gondwana . Tuhua Orogeny in New Zealand tapers off . </Td> <Td> 330.9 ± 0.2 </Td> </Tr> <Tr> <Td> Viséan </Td> <Td> 346.7 ± 0.4 </Td> </Tr> <Tr> <Td> Tournaisian </Td> <Td> 358.9 ± 0.4 </Td> </Tr> <Tr> <Td> Devonian </Td> <Td> Late </Td> <Td> Famennian </Td> <Td> First clubmosses, horsetails and ferns appear, as do the first seed - bearing plants (progymnosperms), first trees (the progymnosperm Archaeopteris), and first (wingless) insects . Strophomenid and atrypid brachiopods, rugose and tabulate corals, and crinoids are all abundant in the oceans . Goniatite ammonoids are plentiful, while squid - like coleoids arise . Trilobites and armoured agnaths decline, while jawed fishes (placoderms, lobe - finned and ray - finned fish, and early sharks) rule the seas . First amphibians still aquatic. "Old Red Continent" of Euramerica . Beginning of Acadian Orogeny for Anti-Atlas Mountains of North Africa, and Appalachian Mountains of North America, also the Antler, Variscan, and Tuhua Orogeny in New Zealand . </Td> <Td> 372.2 ± 1.6 </Td> </Tr> <Tr> <Td> Frasnian </Td> <Td> 382.7 ± 1.6 </Td> </Tr> <Tr> <Td> Middle </Td> <Td> Givetian </Td> <Td> 387.7 ± 0.8 </Td> </Tr> <Tr> <Td> Eifelian </Td> <Td> 393.3 ± 1.2 </Td> </Tr> <Tr> <Td> Early </Td> <Td> Emsian </Td> <Td> 407.6 ± 2.6 </Td> </Tr> <Tr> <Td> Pragian </Td> <Td> 410.8 ± 2.8 </Td> </Tr> <Tr> <Td> Lochkovian </Td> <Td> 419.2 ± 3.2 </Td> </Tr> <Tr> <Td> Silurian </Td> <Td_colspan="2"> Pridoli </Td> <Td> First vascular plants (the rhyniophytes and their relatives), first millipedes and arthropleurids on land . First jawed fishes, as well as many armoured jawless fish, populate the seas . Sea - scorpions reach large size . Tabulate and rugose corals, brachiopods (Pentamerida, Rhynchonellida, etc .), and crinoids all abundant . Trilobites and mollusks diverse; graptolites not as varied . Beginning of Caledonian Orogeny for hills in England, Ireland, Wales, Scotland, and the Scandinavian Mountains . Also continued into Devonian period as the Acadian Orogeny, above . Taconic Orogeny tapers off . Lachlan Orogeny on Australian continent tapers off . </Td> <Td> 423 ± 2.3 </Td> </Tr> <Tr> <Td> Ludlow </Td> <Td> Ludfordian </Td> <Td> 425.6 ± 0.9 </Td> </Tr> <Tr> <Td> Gorstian </Td> <Td> 427.4 ± 0.5 </Td> </Tr> <Tr> <Td> Wenlock </Td> <Td> Homerian </Td> <Td> 430.5 ± 0.7 </Td> </Tr> <Tr> <Td> Sheinwoodian </Td> <Td> 433.4 ± 0.8 </Td> </Tr> <Tr> <Td> Llandovery </Td> <Td> Telychian </Td> <Td> 438.5 ± 1.1 </Td> </Tr> <Tr> <Td> Aeronian </Td> <Td> 440.8 ± 1.2 </Td> </Tr> <Tr> <Td> Rhuddanian </Td> <Td> 443.8 ± 1.5 </Td> </Tr> <Tr> <Td> Ordovician </Td> <Td> Late </Td> <Td> Hirnantian </Td> <Td> Invertebrates diversify into many new types (e.g., long straight - shelled cephalopods). Early corals, articulate brachiopods (Orthida, Strophomenida, etc .), bivalves, nautiloids, trilobites, ostracods, bryozoa, many types of echinoderms (crinoids, cystoids, starfish, etc .), branched graptolites, and other taxa all common . Conodonts (early planktonic vertebrates) appear . First green plants and fungi on land . Ice age at end of period . </Td> <Td> 445.2 ± 1.4 </Td> </Tr> <Tr> <Td> Katian </Td> <Td> 453 ± 0.7 </Td> </Tr> <Tr> <Td> Sandbian </Td> <Td> 458.4 ± 0.9 </Td> </Tr> <Tr> <Td> Middle </Td> <Td> Darriwilian </Td> <Td> 467.3 ± 1.1 </Td> </Tr> <Tr> <Td> Dapingian </Td> <Td> 470 ± 1.4 </Td> </Tr> <Tr> <Td> Early </Td> <Td> Floian (formerly Arenig) </Td> <Td> 477.7 ± 1.4 </Td> </Tr> <Tr> <Td> Tremadocian </Td> <Td> 485.4 ± 1.9 </Td> </Tr> <Tr> <Td> Cambrian </Td> <Td> Furongian </Td> <Td> Stage 10 </Td> <Td> Major diversification of life in the Cambrian Explosion . Numerous fossils; most modern animal phyla appear . First chordates appear, along with a number of extinct, problematic phyla . Reef - building Archaeocyatha abundant; then vanish . Trilobites, priapulid worms, sponges, inarticulate brachiopods (unhinged lampshells), and numerous other animals . Anomalocarids are giant predators, while many Ediacaran fauna die out . Prokaryotes, protists (e.g., forams), fungi and algae continue to present day . Gondwana emerges . Petermann Orogeny on the Australian continent tapers off (550--535 Ma). Ross Orogeny in Antarctica . Adelaide Geosyncline (Delamerian Orogeny), majority of orogenic activity from 514--500 Ma . Lachlan Orogeny on Australian continent, c. 540--440 Ma . Atmospheric CO content roughly 20--35 times present - day (Holocene) levels (6000 ppmv compared to today's 385 ppmv) </Td> <Td> ~ 489.5 </Td> </Tr> <Tr> <Td> Jiangshanian </Td> <Td> ~ 494 </Td> </Tr> <Tr> <Td> Paibian </Td> <Td> ~ 497 </Td> </Tr> <Tr> <Td> Series 3 </Td> <Td> Guzhangian </Td> <Td> ~ 500.5 </Td> </Tr> <Tr> <Td> Drumian </Td> <Td> ~ 504.5 </Td> </Tr> <Tr> <Td> Stage 5 </Td> <Td> ~ 509 </Td> </Tr> <Tr> <Td> Series 2 </Td> <Td> Stage 4 </Td> <Td> ~ 514 </Td> </Tr> <Tr> <Td> Stage 3 </Td> <Td> ~ 521 </Td> </Tr> <Tr> <Td> Terreneuvian </Td> <Td> Stage 2 </Td> <Td> ~ 529 </Td> </Tr> <Tr> <Td> Fortunian </Td> <Td> ~ 541 ± 1.0 </Td> </Tr> <Tr> <Td> Precambrian </Td> <Td> Proterozoic </Td> <Td> Neoproterozoic </Td> <Td> Ediacaran </Td> <Td_colspan="3"> Good fossils of the first multi-celled animals . Ediacaran biota flourish worldwide in seas . Simple trace fossils of possible worm - like Trichophycus, etc . First sponges and trilobitomorphs . Enigmatic forms include many soft - jellied creatures shaped like bags, disks, or quilts (like Dickinsonia). Taconic Orogeny in North America . Aravalli Range orogeny in Indian Subcontinent . Beginning of Petermann Orogeny on Australian continent . Beardmore Orogeny in Antarctica, 633--620 Ma . </Td> <Td> ~ 635 </Td> </Tr> <Tr> <Td> Cryogenian </Td> <Td_colspan="3"> Possible "Snowball Earth" period . Fossils still rare . Rodinia landmass begins to break up . Late Ruker / Nimrod Orogeny in Antarctica tapers off . </Td> <Td> ~ 720 </Td> </Tr> <Tr> <Td> Tonian </Td> <Td_colspan="3"> Rodinia supercontinent persists . Sveconorwegian orogeny ends . Trace fossils of simple multi-celled eukaryotes . First radiation of dinoflagellate - like acritarchs . Grenville Orogeny tapers off in North America . Pan-African orogeny in Africa . Lake Ruker / Nimrod Orogeny in Antarctica, 1,000 ± 150 Ma . Edmundian Orogeny (c. 920--850 Ma), Gascoyne Complex, Western Australia . Adelaide Geosyncline laid down on Australian continent, beginning of Adelaide Geosyncline (Delamerian Orogeny) in Australia . </Td> <Td> 1000 </Td> </Tr> <Tr> <Td> Mesoproterozoic </Td> <Td> Stenian </Td> <Td_colspan="3"> Narrow highly metamorphic belts due to orogeny as Rodinia forms . Sveconorwegian orogeny starts . Late Ruker / Nimrod Orogeny in Antarctica possibly begins . Musgrave Orogeny (c . 1,080 Ma), Musgrave Block, Central Australia . </Td> <Td> 1200 </Td> </Tr> <Tr> <Td> Ectasian </Td> <Td_colspan="3"> Platform covers continue to expand . Green algae colonies in the seas . Grenville Orogeny in North America . </Td> <Td> 1400 </Td> </Tr> <Tr> <Td> Calymmian </Td> <Td_colspan="3"> Platform covers expand . Barramundi Orogeny, McArthur Basin, Northern Australia, and Isan Orogeny, c. 1,600 Ma, Mount Isa Block, Queensland </Td> <Td> 1600 </Td> </Tr> <Tr> <Td> Paleoproterozoic </Td> <Td> Statherian </Td> <Td_colspan="3"> First complex single - celled life: protists with nuclei . Columbia is the primordial supercontinent . Kimban Orogeny in Australian continent ends . Yapungku Orogeny on Yilgarn craton, in Western Australia . Mangaroon Orogeny, 1,680--1,620 Ma, on the Gascoyne Complex in Western Australia . Kararan Orogeny (1,650 Ma), Gawler Craton, South Australia . </Td> <Td> 1800 </Td> </Tr> <Tr> <Td> Orosirian </Td> <Td_colspan="3"> The atmosphere becomes oxygenic . Vredefort and Sudbury Basin asteroid impacts . Much orogeny . Penokean and Trans - Hudsonian Orogenies in North America . Early Ruker Orogeny in Antarctica, 2,000--1,700 Ma . Glenburgh Orogeny, Glenburgh Terrane, Australian continent c . 2,005--1,920 Ma . Kimban Orogeny, Gawler craton in Australian continent begins . </Td> <Td> 2050 </Td> </Tr> <Tr> <Td> Rhyacian </Td> <Td_colspan="3"> Bushveld Igneous Complex forms . Huronian glaciation . </Td> <Td> 2300 </Td> </Tr> <Tr> <Td> Siderian </Td> <Td_colspan="3"> Oxygen catastrophe: banded iron formations forms . Sleaford Orogeny on Australian continent, Gawler Craton 2,440--2,420 Ma . </Td> <Td> 2500 </Td> </Tr> <Tr> <Td> Archean </Td> <Td> Neoarchean </Td> <Td_colspan="4"> Stabilization of most modern cratons; possible mantle overturn event . Insell Orogeny, 2,650 ± 150 Ma . Abitibi greenstone belt in present - day Ontario and Quebec begins to form, stabilizes by 2,600 Ma . </Td> <Td> 2800 </Td> </Tr> <Tr> <Td> Mesoarchean </Td> <Td_colspan="4"> First stromatolites (probably colonial cyanobacteria). Oldest macrofossils . Humboldt Orogeny in Antarctica . Blake River Megacaldera Complex begins to form in present - day Ontario and Quebec, ends by roughly 2,696 Ma . </Td> <Td> 3200 </Td> </Tr> <Tr> <Td> Paleoarchean </Td> <Td_colspan="4"> First known oxygen - producing bacteria . Oldest definitive microfossils . Oldest cratons on Earth (such as the Canadian Shield and the Pilbara Craton) may have formed during this period . Rayner Orogeny in Antarctica . </Td> <Td> 3600 </Td> </Tr> <Tr> <Td> Eoarchean </Td> <Td_colspan="4"> Simple single - celled life (probably bacteria and archaea). Oldest probable microfossils . The first life forms and self - replicating RNA molecules evolve around 4,000 Ma, after the Late Heavy Bombardment ends on Earth . Napier Orogeny in Antarctica, 4,000 ± 200 Ma . </Td> <Td> ~ 4000 </Td> </Tr> <Tr> <Td> Hadean </Td> <Td> Early Imbrian (Neohadean) (unofficial) </Td> <Td_colspan="4"> Indirect photosynthetic evidence (e.g., kerogen) of primordial life . This era overlaps the beginning of the Late Heavy Bombardment of the Inner Solar System, produced possibly by the planetary migration of Neptune into the Kuiper belt as a result of orbital resonances between Jupiter and Saturn . Oldest known rock (4,031 to 3,580 Ma). </Td> <Td> 4130 </Td> </Tr> <Tr> <Td> Nectarian (Mesohadean) (unofficial) </Td> <Td_colspan="4"> Possible first appearance of plate tectonics . This unit gets its name from the lunar geologic timescale when the Nectaris Basin and other greater lunar basins form by big impact events . Earliest evidence for life based on unusually high amounts of light isotopes of carbon, a common sign of life . </Td> <Td> 4280 </Td> </Tr> <Tr> <Td> Basin Groups (Paleohadean) (unofficial) </Td> <Td_colspan="4"> End of the Early Bombardment Phase . Oldest known mineral (Zircon, 4,404 ± 8 Ma). Asteroids and comets bring water to Earth . </Td> <Td> 4533 </Td> </Tr> <Tr> <Td> Cryptic (Eohadean) (unofficial) </Td> <Td_colspan="4"> Formation of Moon (4,533 to 4,527 Ma), probably from giant impact, since the end of this era . Formation of Earth (4,570 to 4,567.17 Ma), Early Bombardment Phase begins . Formation of Sun (4,680 to 4,630 Ma). </Td> <Td> 4600 </Td> </Tr> </Table> <Tr> <Th> (hide) Supereon </Th> <Th> Eon </Th> <Th> Era </Th> <Th> Period </Th> <Th> Epoch </Th> <Th> Age </Th> <Th> Major events </Th> <Th> Start, million years ago </Th> </Tr>

When did humans first appear in geologic time
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