CKM 2018-19 / Aziz Yardımlı



Geologic time scale

Geologic time scale (W)


This clock representation shows some of the major units of geological time and definitive events of Earth history. The Hadean eon represents the time before fossil record of life on Earth; its upper boundary is now regarded as 4.0 Ga (billion years ago).[1] Other subdivisions reflect the evolution of life; the Archean and Proterozoic are both eons, the Palaeozoic, Mesozoic and Cenozoic are eras of the Phanerozoic eon. The three million year Quaternary period, the time of recognizable humans, is too small to be visible at this scale.

In this timeline, Ma (for megaannum) means "million years ago," ka (for kiloannum) means "thousand years ago," and ya means "years ago." 


Evidence from radiometric dating indicates that Earth is about 4.54 billion years old.

The primary defined divisions of tim are eons, in sequence the Hadean, the Archean, the Proterozoic and the Phanerozoic. The first three of these can be referred to collectively as the Precambrian supereon. Eons are divided into eras, which are in turn divided into periods, epochs and ages.

The following four timelines show the geologic time scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. Therefore, the second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in the third timeline, and the most recent period is expanded in the fourth timeline


Siderian Rhyacian Orosirian Statherian Calymmian Ectasian Stenian Tonian Cryogenian Ediacaran Eoarchean Paleoarchean Mesoarchean Neoarchean Paleoproterozoic Mesoproterozoic Neoproterozoic Paleozoic Mesozoic Cenozoic Hadean Archean Proterozoic Phanerozoic Precambrian
Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleogene Neogene Quaternary Paleozoic Mesozoic Cenozoic Phanerozoic
Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Holocene Paleogene Neogene Quaternary Cenozoic
Gelasian Calabrian (stage) Pleistocene Pleistocene Pleistocene Holocene Quaternary
Millions of Years


Corresponding to eons, eras, periods, epochs and ages, the terms "eonothem", "erathem", "system", "series", "stage" are used to refer to the layers of rock that belong to these stretches of geologic time in Earth's history.

Geologists qualify these units as "early", "mid", and "late" when referring to time, and "lower", "middle", and "upper" when referring to the corresponding rocks. For example, the lower Jurassic Series in chronostratigraphy corresponds to the early Jurassic Epoch in geochronology.[2] The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" but "Early Jurassic."


Table of geologic time (LINK)
The following table summarizes the major events and characteristics of the periods of time making up the geologic time scale. This table is arranged with the most recent geologic periods at the top, and the most ancient at the bottom. The height of each table entry does not correspond to the duration of each subdivision of time.

The content of the table is based on the current official geologic time scale of the International Commission on Stratigraphy,[1] with the epoch names altered to the early/late format from lower/upper as recommended by the ICS when dealing with chronostratigraphy.[2]

Supereon Eon Era Period[b] Epoch Age[c] Major events Start, million years ago[c]
n/a[d] Phanerozoic Cenozoic[e] Quaternary Holocene

Meghalayan · Northgrippian · Greenlandian

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 CO2 levels rise from around 280 parts per million volume (ppmv) to the current level of 400[29] ppmv.[30][f] 0.0117[g]
Pleistocene Late (locally Tarantian · Tyrrhenian · Eemian · Sangamonian) 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 CO2 levels[30][f]), 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. 0.126
Middle (formerly Ionian[citation needed]) 0.781
Calabrian 1.8*
Gelasian 2.58*
Neogene Pliocene Piacenzian 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. 3.6*
Zanclean 5.333*
Miocene Messinian 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 CO2, gradually lowering the level of atmospheric CO2 from 650 ppmv down to around 100 ppmv.[30][f] 7.246*
Tortonian 11.63*
Serravallian 13.82*
Langhian 15.97
Burdigalian 20.44
Aquitanian 23.03*
Paleogene Oligocene Chattian 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 28.1
Rupelian 33.9*
Eocene Priabonian 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,[30][f] 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. 37.8
Bartonian 41.2
Lutetian 47.8*
Ypresian 56*
Paleocene Thanetian Climate tropical. Modern plants appear; Mammals diversify into a number of primitive lineages following the extinction of the non-avian 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. 59.2*
Selandian 61.6*
Danian 66*
Mesozoic Cretaceous Late Maastrichtian 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 CO2 close to present-day levels. 72.1 ± 0.2*
Campanian 83.6 ± 0.2
Santonian 86.3 ± 0.5*
Coniacian 89.8 ± 0.3
Turonian 93.9*
Cenomanian 100.5*
Early Albian ~113
Aptian ~125
Barremian ~129.4
Hauterivian ~132.9
Valanginian ~139.8
Berriasian ~145
Jurassic Late Tithonian 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 CO2 levels 3–4 times the present day levels (1200–1500 ppmv, compared to today's 400 ppmv[30][f]). 152.1 ± 0.9
Kimmeridgian 157.3 ± 1.0
Oxfordian 163.5 ± 1.0
Middle Callovian 166.1 ± 1.2
Bathonian 168.3 ± 1.3*
Bajocian 170.3 ± 1.4*
Aalenian 174.1 ± 1.0*
Early Toarcian 182.7 ± 0.7*
Pliensbachian 190.8 ± 1.0*
Sinemurian 199.3 ± 0.3*
Hettangian 201.3 ± 0.2*
Triassic Late Rhaetian 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. Dicroidiumflora 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) ~208.5
Norian ~227
Carnian ~237*
Middle Ladinian ~242*
Anisian 247.2
Early Olenekian 251.2
Induan 251.902 ± 0.06*
Paleozoic Permian Lopingian Changhsingian 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. 254.14 ± 0.07*
Wuchiapingian 259.1 ± 0.4*
Guadalupian Capitanian 265.1 ± 0.4*
Wordian 268.8 ± 0.5*
Roadian 272.95 ± 0.5*
Cisuralian Kungurian 283.5 ± 0.6
Artinskian 290.1 ± 0.26
Sakmarian 295 ± 0.18
Asselian 298.9 ± 0.15*
Pennsylvanian Gzhelian 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. 303.7 ± 0.1
Kasimovian 307 ± 0.1
Moscovian 315.2 ± 0.2
Bashkirian 323.2 ± 0.4*
Mississippian Serpukhovian 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. 330.9 ± 0.2
Viséan 346.7 ± 0.4*
Tournaisian 358.9 ± 0.4*
Devonian Late Famennian 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. 372.2 ± 1.6*
Frasnian 382.7 ± 1.6*
Middle Givetian 387.7 ± 0.8*
Eifelian 393.3 ± 1.2*
Early Emsian 407.6 ± 2.6*
Pragian 410.8 ± 2.8*
Lochkovian 419.2 ± 3.2*
Silurian Pridoli 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. 423 ± 2.3*
Ludlow Ludfordian 425.6 ± 0.9*
Gorstian 427.4 ± 0.5*
Wenlock Homerian 430.5 ± 0.7*
Sheinwoodian 433.4 ± 0.8*
Llandovery Telychian 438.5 ± 1.1*
Aeronian 440.8 ± 1.2*
Rhuddanian 443.8 ± 1.5*
Ordovician Late Hirnantian 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. 445.2 ± 1.4*
Katian 453 ± 0.7*
Sandbian 458.4 ± 0.9*
Middle Darriwilian 467.3 ± 1.1*
Dapingian 470 ± 1.4*
Early Floian
(formerly Arenig)
477.7 ± 1.4*
Tremadocian 485.4 ± 1.9*
Cambrian Furongian Stage 10 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 CO2 content roughly 15 times present-day (Holocene) levels (6000 ppmv compared to today's 400 ppmv)[30][f] ~489.5
Jiangshanian ~494*
Paibian ~497*
Miaolingian Guzhangian ~500.5*
Drumian ~504.5*
Wuliuan ~509
Series 2 Stage 4 ~514
Stage 3 ~521
Terreneuvian Stage 2 ~529
Fortunian ~541 ± 1.0*
Precambrian[i] Proterozoic[j] Neoproterozoic[j] Ediacaran 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. ~635*
Cryogenian Possible "Snowball Earth" period. Fossils still rare. Rodinia landmass begins to break up. Late Ruker / Nimrod Orogeny in Antarctica tapers off. ~720[k]
Tonian 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. 1000[k]
Mesoproterozoic[j] Stenian 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. 1200[k]
Ectasian Platform covers continue to expand. Green algae colonies in the seas. Grenville Orogeny in North America. 1400[k]
Calymmian Platform covers expand. Barramundi Orogeny, McArthur Basin, Northern Australia, and Isan Orogeny, c.1,600 Ma, Mount Isa Block, Queensland 1600[k]
Paleoproterozoic[j] Statherian 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. 1800[k]
Orosirian 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. 2050[k]
Rhyacian Bushveld Igneous Complex forms. Huronian glaciation. 2300[k]
Siderian Oxygen catastrophe: banded iron formations forms. Sleaford Orogeny on Australian continent, Gawler Craton 2,440–2,420 Ma. 2500[k]
Archean[j] Neoarchean[j] 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. 2800[k]
Mesoarchean[j] 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. 3200[k]
Paleoarchean[j] 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.[l] Rayner Orogeny in Antarctica. 3600[k]
Eoarchean[j] 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. ~4000
Hadean[j][m] Early Imbrian (Neohadean) (unofficial)[j][n] 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).[32] 4130[33]
Nectarian (Mesohadean) (unofficial)[j][n] 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. 4280[33]
Basin Groups (Paleohadean) (unofficial)[j][n] End of the Early Bombardment Phase. Oldest known mineral (Zircon, 4,404 ± 8 Ma). Asteroids and comets bring water to Earth.[34] 4533[33]
Cryptic (Eohadean) (unofficial)[j][n] 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) . 4600




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