Timeline of Earth


This timeline of Earth's history summarizes significant geological and biological events from the formation of the Earth to the arrival of modern humans. Times are listed in millions of years, or megaanni.

Dating of the geologic record

The geologic record is the strata of rock in the planet's crust and the science of geology is much concerned with the age and origin of all rocks to determine the history and formation of Earth and to understand the forces that have acted upon it. Geologic time is the timescale used to calculate dates in the planet's geologic history from its origin to the present day.
Radiometric dating measures the steady decay of radioactive elements in an object to determine its age. It is used to calculate dates for the older part of the planet's geological record. The theory is very complicated but, in essence, the radioactive elements within an object decay to form isotopes of each chemical element. Isotopes are atoms of the element that differ in mass but share the same general properties. Geologists are most interested in the decay of isotopes carbon-14 and potassium-40. Carbon-14 aka radiocarbon dating works for organic materials that are less than about 50,000 years old. For older periods, the potassium-argon dating process is more accurate.
Radiocarbon dating is carried out by measuring how much of the carbon-14 and nitrogen-14 isotopes are found in a material. The ratio between the two is used to estimate the material's age. Suitable materials include wood, charcoal, paper, fabrics, fossils and shells. It is assumed that rock exists in layers according to age, with older beds below later ones. This is the basis of stratigraphy.
The ages of more recent layers are calculated primarily by the study of fossils, which are remains of ancient life preserved in the rock. These occur consistently and so a theory is feasible. Most of the boundaries in recent geologic time coincide with extinctions and with the appearances of new species.

The earliest Solar System

In the earliest Solar System history, the Sun, the planetesimals and the giant planets were formed. The inner Solar System aggregated more slowly than the outer, so the terrestrial planets were not yet formed, including Earth and Moon.

Eoarchean Era

The Proterozoic saw the first traces of biological activity. Fossil remains of bacteria and algae.

Paleoproterozoic Era

Siderian Period

  • c. 2,500 Ma – Proterozoic Eon, Paleoproterozoic Era, and Siderian Period start. Oxygen saturation in the oceans is reached: Banded iron formations form and saturate ocean floor depositswithout an oxygen sink, Earth's atmosphere becomes highly oxygenic. Great Oxidation Event led by cyanobacteria's oxygenic photosynthesisvarious forms of Archaea and anoxic bacteria become extinct in first great extinction event on Earth. Algoman Orogeny or Kenoran: assembly of Arctica out of the Canadian Laurentian Shield and Siberian cratonformation of Angaran Shield and Slave Province.
  • c. 2,440 Ma – Formation of Gawler craton in Australia.
  • c. 2,400 Ma – Huronian glaciation starts, probably from oxidation of earlier methane greenhouse gas produced by burial of organic sediments of photosynthesizers. Formation of Dharwar Craton in southern India.
  • c. 2,400 Ma – Dharwar Craton in southern India stabilizes.

    Rhyacian Period

  • c. 2,300 Ma – Rhyacian period starts.
  • c. 2,250 Ma – Bushveld Igneous Complex forms: world's largest reserves of platinum-group metals, as well as vast quantities of iron, tin, chromium, titanium and vanadium appear – formation of Transvaal Basin begins.
  • c. 2,200–1800 Ma – Continental Red Beds found, produced by iron in weathered sandstone being exposed to oxygen. Eburnean Orogeny, series of tectonic, metamorphic and plutonic events establish Eglab Shield to the north of West African Craton and Man Shield to its south – Birimian domain of West Africa established and structured.
  • c. 2,200 Ma – Iron content of ancient fossil soils shows an oxygen built up to 5–18% of current levels. End of Kenoran Orogeny: invasion of Superior and Slave Provinces by basaltic dikes and sills – Wyoming and Montana arm of Superior Province experiences intrusion of 5 km thick sheet of chromite-bearing gabbroic rock as Stillwater Complex forms.
  • c. 2,100 Ma – Huronian glaciation ends. Earliest known eukaryote fossils found. Earliest multicellular organisms collectively referred to as the "Gabonionta" ; Wopmay orogeny along western margin of Canadian Shield.
  • c. 2,090 Ma – Eburnean Orogeny: Eglab Shield experiences syntectonic trondhjemitic pluton intrusion of its Chegga series – most of the intrusion is in the form of a plagioclase called oligoclase.
  • 2.070 Ma – Eburnean Orogeny: asthenospheric upwelling releases large volume of post-orogenic magmas – magma events repeatedly reactivated from the Neoproterozoic to the Mesozoic.

    Orosirian Period

  • c. 2,050 Ma – Orosirian Period starts. Significant orogeny in most continents.
  • c. 2,023 Ma – Vredefort impact structure forms.
  • c. 2,005 Ma – Glenburgh Orogeny begins: Glenburgh terrane in western Australia begins to stabilize during period of substantial granite magmatism and deformation; Halfway Gneiss and Moogie Metamorphics result. Dalgaringa Supersuite, comprising sheets, dykes and viens of mesocratic and leucocratic tonalite, stabilizes.
  • c. 2,000 Ma – The lesser supercontinent Atlantica forms. The Oklo natural nuclear reactor of Gabon produced by uranium-precipitant bacteria.
  • c. 1,900–,880 Ma – Gunflint chert biota forms flourishes including prokaryotes like Kakabekia, Gunflintia, Animikiea and Eoastrion
  • c. 1,850 Ma – Sudbury impact structure. Penokean orogeny. Bacterial viruses emerge before, or soon after, the divergence of the prokaryotic and eukaryotic lineages.
  • c. 1,830 Ma – Capricorn Orogeny stabilizes central and northern Gascoyne Complex: formation of pelitic and psammitic schists known as Morrissey Metamorphics and depositing Pooranoo Metamorphics an amphibolite facies

    Statherian Period

  • c. 1,800 Ma – Statherian Period starts. Supercontinent Columbia forms, one of whose fragments being Nena. Oldest ergs develop on several cratons Barramundi Orogeny influences MacArthur Basin in Northern Australia.
  • c. 1,780 Ma – Colorado Orogeny influences southern margin of Wyoming craton–collision of Colorado orogen and Trans-Hudson orogen with stabilized Archean craton structure
  • c. 1,770 Ma – Big Sky Orogeny influences southwest Montana: collision between Hearne and Wyoming cratons
  • c. 1,765 Ma – As Kimban Orogeny in Australian continent slows, Yapungku Orogeny begins affecting Yilgarn craton in Western Australiapossible formation of Darling Fault, one of longest and most significant in Australia
  • c. 1,760 Ma – Yavapai Orogeny impacts mid- to south-western United States; Concentrated uranium deposits in Oklo, Gabon, in West Africa are activated after being inundated with ground water in what amounts to a natural nuclear reaction – Reactions continue off and on probably never exceeding 100 kilowatts of thermal power during this time
  • c. 1,750 Ma – Gothian Orogeny : formation of tonalitic-granodioritic plutonic rocks and calc-alkaline volcanites in the East European Craton
  • c. 1,700 Ma – Stabilization of second major continental mass, the Guiana Shield in South America.
  • c. 1,680 Ma – Mangaroon Orogeny, on the Gascoyne Complex in Western Australia: Durlacher Supersuite, granite intrusion featuring a northern and southern beltheavily sheared orthoclase porphyroclastic granites
  • c. 1,650 Ma – Kararan Orogeny uplifts great mountains on the Gawler craton in Southern Australiaformation of Gawler Range including picturesque Conical Hill Track and "Organ Pipes" waterfall

    Mesoproterozoic Era

Calymmian Period

  • c. 1,600 Ma – Mesoproterozoic Era and Calymmian Period start. Platform covers expand. Major orogenic event in Australia: Isan Orogeny influences Mount Isa Block of Queenslandmajor deposits of lead, silver, copper and zinc are laid down. Mazatzal Orogeny influences mid- to south-western United States: Precambrian rocks of the Grand Canyon, Vishnu Schist and Grand Canyon Series, are formed establishing basement of Canyon with metamorphosed gneisses that are intruded by granites. Belt Supergroup in Montana/Idaho/BC formed in basin on edge of Laurentia.
  • c. 1,500 Ma – Supercontinent Columbia splits apart: associated with continental rifting along western margin of Laurentia, eastern India, southern Baltica, southeastern Siberia, northwestern South Africa and North China Block-formation of Ghats Province in India. First structurally complex eukaryotes.

    Ectasian Period

  • c. 1,400 Ma – Ectasian Period starts. Platform covers expand. Major increase in Stromatolite diversity with widespread blue-green algae colonies and reefs dominating tidal zones of oceans and seas
  • c. 1,300 Ma – Break-up of Columbia Supercontinent completed: widespread anorogenic magmatic activity, forming anorthosite-mangerite-charnockite-granite suites in North America, Baltica, Amazonia and North Chinastabilization of Amazonian Craton in South America Grenville orogeny in North America: globally associated with assembly of Supercontinent Rodinia establishes Grenville Province in Eastern North Americafolded mountains from Newfoundland to North Carolina as Old Rag Mountain forms
  • c. 1,270 Ma – Emplacement of Mackenzie granite mafic dike swarmone of three dozen dike swarms, forms into Mackenzie Large Igneous Provinceformation of Copper Creek deposits
  • c. 1,250 Ma – Sveconorwegian Orogeny begins: essentially a reworking of previously formed crust on the Baltic Shield
  • c. 1,240 Ma – Second major dike swarm, Sudbury dikes form in Northeastern Ontario around the area of the Sudbury Basin

    Stenian Period

  • c. 1,200 Ma – Stenian Period starts. Red alga Bangiomorpha pubescens, earliest fossil evidence for sexually reproducing organism. Meiosis and sexual reproduction are present in single-celled eukaryotes, and possibly in the common ancestor of all eukaryotes. Supercontinent of Rodinia completed: consisting of North American, East European, Amazonian, West African, Eastern Antarctica, Australia and China blocks, largest global system yet formedsurrounded by superocean Mirovia
  • c. 1,100 Ma – First dinoflagellate evolve; photosynthetic, some develop mixotrophic habits of ingesting prey. Thus, they become the first predators, forcing acritarchs to defensive strategies and leading to open "arms" race. Late Ruker and Nimrod Orogenies in Antarctica possibly begins: formation of Gamburtsev mountain range and Vostok Subglacial Highlands. Keweenawan Rift buckles in the south-central part of the North American plateleaves behind thick layers of rock that are exposed in Wisconsin, Minnesota, Iowa and Nebraska and creates rift valley where future Lake Superior develops.
  • c. 1,080 Ma – Musgrave Orogeny forms Musgrave Block, an east–west trending belt of granulite-gneiss basement rocksvoluminous Kulgera Suite of granite and Birksgate Complex solidify
  • c. 1,076 Ma – Musgrave Orogeny: Warakurna large igneous province developsintrusion of Giles Complex and Winburn Suite of granites and deposition of Bentley Supergroup
  • c. 1,010 Ma – Ourasphaira giraldae: multicellular organic-walled microfossils preserved in shale of the Grassy Bay Formation with fungal affinity.

    Neoproterozoic Era

Tonian Period

  • c. 1,000 Ma – Neoproterozoic Era and Tonian Period start. Grenville orogeny ends. First radiation of dinoflagellates and spiny acritarchsincrease in defensive systems indicate that acritarchs are responding to carnivorous habits of dinoflagellatesdecline in stromatolite reef populations begins. Rodinia starts to break up. First vaucherian algae. Rayner Orogeny as proto-India and Antarctica collide. Trace fossils of colonial Horodyskia : possible divergence between animal and plant kingdoms begins. Stabilization of Satpura Province in Northern India.
  • c. 920 Ma – Edmundian Orogeny redefines Gascoyne Complex: consists of reactivation of earlier formed faults in the Gascoynefolding and faulting of overlying Edmund and Collier basins
  • c. 920 Ma – Adelaide Geosyncline laid down in central Australiaessentially a rift complex, consists of thick layer of sedimentary rock and minor volcanics deposited on Easter marginlimestones, shales and sandstones predominate
  • c. 900 Ma – Bitter Springs Formation of Australia: in addition to prokaryote assemblage of fossils, cherts include eukaryotes with ghostly internal structures similar to green algaefirst appearance of Glenobotrydion, among earliest plants on Earth.
  • c. 850 Ma - Start of the Neoproterozoic oxygenation event, a second major increase in atmospheric and oceanic oxygen concentration on Earth.
  • c. 830 Ma – Rift develops on Rodinia between continental masses of Australia, eastern Antarctica, India, Congo and Kalahari on one side and Laurentia, Baltica, Amazonia, West African and Rio de la Plata cratons on otherformation of Adamastor Ocean.
  • c. 800 Ma – With free oxygen levels much higher, carbon cycle is disrupted and once again glaciation becomes severebeginning of second "snowball Earth" event
  • c. 750 Ma – First Protozoa appears: as creatures like Paramecium, Amoeba and Melanocyrillium evolve, first animal-like cells become distinctive from plantsrise of herbivores in the food chain. First Sponge-like animal: similar to early colonial foraminiferan Horodyskia, earliest ancestors of Sponges were colonial cells that circulated food sources using flagella to their gullet to be digested. Kaigas : first thought to be a major glaciation of Earth, however, the Kaigas formation was later determined to be non-glacial.

    Cryogenian Period

  • c. 720 Ma – Cryogenian Period starts, during which Earth freezes over at least 3 times. The Sturtian glaciation continues the process begun during Kaigasgreat ice sheets cover most of the planet stunting evolutionary development of animal and plant lifesurvival based on small pockets of heat under the ice.
  • c. 700 Ma – Fossils of testate Amoeba first appear: first complex metazoans leave unconfirmed biomarkersthey introduce new complex body plan architecture which allows for development of complex internal and external structures. Worm trail impressions in China: because putative "burrows" under stromatolite mounds are of uneven width and tapering makes biological origin difficult to defendstructures imply simple feeding behaviours. Rifting of Rodinia is completed: formation of new superocean of Panthalassa as previous Mirovia ocean bed closesMozambique mobile belt develops as a suture between plates on Congo-Tanzania craton
  • c. 660 Ma – As Sturtian glaciers retreat, Cadomian orogeny begins on north coast of Armorica: involving one or more collisions of island arcs on margin of future Gondwana, terranes of Avalonia, Armorica and Iberia are laid down
  • c. 650 Ma – First Demosponges appear: form first skeletons of spicules made from protein spongin and silicabrightly coloured these colonial creatures filter feed since they lack nervous, digestive or circulatory systems and reproduce both sexually and asexually
  • c. 650 Ma – Final period of worldwide glaciation, Marinoan begins: most significant "snowball Earth" event, global in scope and longerevidence from Diamictite deposits in South Australia laid down on Adelaide Geosyncline

    Ediacaran Period

  • c. 635 Ma – Ediacaran period begins. End of Marinoan Glaciation: last major "snowball Earth" event as future ice ages will feature less overall ice coverage of the planet
  • c. 633 Ma – Beardmore Orogeny in Antarctica: reflection of final break-up of Rodinia as pieces of the supercontinent begin moving together again to form Pannotia
  • c. 620 Ma – Timanide Orogeny affects northern Baltic Shield: gneiss province divided into several north–south trending segments experiences numerous metasedimentary and metavolcanic depositslast major orogenic event of Precambrian
  • c. 602 Ma - Lantian Biota appears, which includes some of the oldest large and complex fossils known.
  • c. 600 Ma – Pan-African Orogeny begins: Arabian-Nubian Shield formed between plates separating supercontinent fragments Gondwana and PannotiaSupercontinent Pannotia completed, bordered by Iapetus and Panthalassa oceans. Accumulation of atmospheric oxygen allows for the formation of ozone layer: prior to this, land-based life would probably have required other chemicals to attenuate ultraviolet radiation enough to permit colonization of the land
  • c. 575 Ma – First Ediacaran-type fossils.
  • c. 565 MaCharnia, a frond-like organism, first evolves.
  • c. 560 Ma – Trace fossils, e.g., worm burrows, and small bilaterally symmetrical animals. Earliest arthropods. Earliest fungi.
  • c. 558 MaDickinsonia, a large slow moving disc-like creature, first appearsthe discovery of fat molecules in its tissues make it the first confirmed true metazoan animal of the fossil record.
  • c. 555 Ma – The first possible mollusk Kimberella appears.
  • c. 550 Ma – First possible comb-jellies, sponges, corals, and anemones.
  • c. 550 MaUluru or Ayers Rock begins forming during the Petermann Orogeny in Australia
  • c. 544 Ma – The small shelly fauna first appears.

    Phanerozoic Eon

Paleozoic Era

Cambrian Period

Triassic Period

Paleogene Period

Visual summary