Scientific Cosmological Timeline of Natural History

https://en.wikipedia.org/wiki/Timeline_of_natural_history This timeline of natural 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 (Ma). Dating of the geologic record Edit The geologic record is the strata (layers) 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 (currently estimated to have been some 4,600 million years ago) 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 (into nitrogen-14) and potassium-40 (into argon-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 (e.g., the dinosaurs) and with the appearances of new species (e.g., hominids). The earliest Solar System Edit Main articles: Formation and evolution of the Solar System and Nebular hypothesis In the earliest Solar System history, the Sun, the planetesimals and the jovian 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. c. 4,570 Ma – A supernova explosion (known as the primal supernova) seeds our galactic neighborhood with heavy elements that will be incorporated into the Earth, and results in a shock wave in a dense region of the Milky Way galaxy. The Ca-Al-rich inclusions, which formed 2 million years before the chondrules,[1] are a key signature of a supernova explosion. c. 4,567 ±3 Ma – Rapid collapse of hydrogen molecular cloud, forming a third-generation Population I star, the Sun, in a region of the Galactic Habitable Zone (GHZ), about 25,000 light years from the center of the Milky Way Galaxy.[2] c. 4,566 ±2 Ma – A protoplanetary disc (from which Earth eventually forms) emerges around the young Sun, which is in its T Tauri stage. c. 4,560–4,550 Ma – Proto-Earth forms at the outer (cooler) edge of the habitable zone of the Solar System. At this stage the solar constant of the Sun was only about 73% of its current value, but liquid water may have existed on the surface of the Proto-Earth, probably due to the greenhouse warming of high levels of methane and carbon dioxide present in the atmosphere. Early bombardment phase begins: because the solar neighbourhood is rife with large planetoids and debris, Earth experiences a number of giant impacts that help to increase its overall size. Precambrian Supereon Edit Main article: Precambrian c. 4,533 Ma – The Precambrian (to c. 539 Ma[3]), now termed a "supereon" but formerly an era, is split into three geological time intervals called eons: Hadean, Archaean and Proterozoic. The latter two are sub-divided into several eras as currently defined. In total, the Precambrian comprises some 85% of geological time from the formation of Earth to the time when creatures first developed exoskeletons (i.e., hard outer parts) and thereby left abundant fossil remains. Hadean Eon Edit Main article: Hadean c. 4,533 Ma – Hadean Eon, Precambrian Supereon and unofficial Cryptic era start as the Earth–Moon system forms, possibly as a result of a glancing collision between proto-Earth and the hypothetical protoplanet Theia. (The Earth was considerably smaller than now, before this impact.) This impact vaporized a large amount of the crust, and sent material into orbit around Earth, which lingered as rings, similar to those of Saturn, for a few million years, until they coalesced to become the Moon. The Moon geology pre-Nectarian period starts. Earth was covered by a magmatic ocean 200 kilometres (120 mi) deep resulting from the impact energy from this and other planetesimals during the early bombardment phase, and energy released by the planetary core forming. Outgassing from crustal rocks gives Earth a reducing atmosphere of methane, nitrogen, hydrogen, ammonia, and water vapour, with lesser amounts of hydrogen sulfide, carbon monoxide, then carbon dioxide. With further full outgassing over 1000–1500 K, nitrogen and ammonia become lesser constituents, and comparable amounts of methane, carbon monoxide, carbon dioxide, water vapour, and hydrogen are released. c. 4,500 Ma – Sun enters main sequence: a solar wind sweeps the Earth-Moon system clear of debris (mainly dust and gas). End of the Early Bombardment Phase. Basin Groups Era begins on Earth. c. 4,450 Ma – 100 million years after the Moon formed, the first lunar crust, formed of lunar anorthosite, differentiates from lower magmas. The earliest Earth crust probably forms similarly out of similar material. On Earth the pluvial period starts, in which the Earth's crust cools enough to let oceans form. c. 4,404 Ma – First known mineral, found at Jack Hills in Western Australia. Detrital zircons show presence of a solid crust and liquid water. Latest possible date for a secondary atmosphere to form, produced by the Earth's crust outgassing, reinforced by water and possibly organic molecules delivered by comet impacts and carbonaceous chondrites (including type CI shown to be high in a number of amino acids and polycyclic aromatic hydrocarbons (PAH)). c. 4,300 Ma – Nectarian Era begins on Earth. c. 4,250 Ma – Earliest evidence for life, based on unusually high amounts of light isotopes of carbon, a common sign of life, found in Earth's oldest mineral deposits located in the Jack Hills of Western Australia.[4] c. 4,100 Ma – Early Imbrian Era begins on Earth. Late heavy bombardment of the Moon (and probably of the Earth as well) by bolides and asteroids, produced possibly by the planetary migration of Neptune into the Kuiper belt as a result of orbital resonances between Jupiter and Saturn.[5] "Remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia.[6][7] According to one of the researchers, "If life arose relatively quickly on Earth ... then it could be common in the universe."[6] c. 4,030 Ma – Acasta Gneiss of Northwest Territories, Canada, first known oldest rock, or aggregate of minerals. Archean Eon Edit Main article: Archean Eoarchean Era Edit Main article: Eoarchean c. 4,000 Ma – Archean Eon and Eoarchean Era start. Possible first appearance of plate tectonic activity in the Earth's crust as plate structures may have begun appearing. Possible beginning of Napier Mountains Orogeny forces of faulting and folding create first metamorphic rocks. Origins of life. c. 3,930 Ma – Possible stabilization of Canadian Shield begins c. 3,920–3,850 Ma – Final phase of Late Heavy Bombardment c. 3,850 Ma – Greenland apatite shows evidence of 12C enrichment, characteristic of the presence of photosynthetic life.[8] c. 3,850 Ma – Evidence of life: Akilia Island graphite off Western Greenland contains evidence of kerogen, of a type consistent with photosynthesis.[citation needed] c. 3,800 Ma – Oldest banded iron formations found.[9] First complete continental masses or cratons, formed of granite blocks, appear on Earth. Occurrence of initial felsic igneous activity on eastern edge of Antarctic craton as first great continental mass begins to coalesce. East European Craton begins to form – first rocks of the Ukrainian Shield and Voronezh Massif are laid down c. 3,750 Ma – Nuvvuagittuq Greenstone Belt forms c. 3,700 Ma – Graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in Western Greenland[10] Stabilization of Kaapval craton begins: old tonaltic gneisses laid down Paleoarchean Era Edit c. 3,600 Ma – Paleoarchean Era starts. Possible assembly of the Vaalbara supercontinent; oldest cratons on Earth (such as the Canadian Shield, East European Craton and Kaapval) begin growing as a result of crustal disturbances along continents coalescing into Vaalbara – Pilbara Craton stabilizes. Formation of Barberton greenstone belt: Makhonjwa Mountains uplifts on the eastern edge of Kaapval craton, oldest mountains in Africa – area called the "genesis of life" for exceptional preservation of fossils. Narryer Gneiss Terrane stabilizes: these gneisses become the "bedrock" for the formation of the Yilgarn Craton in Australia – noted for the survival of the Jack Hills where the oldest mineral, a zircon was uncovered. c. 3,500 Ma – Lifetime of the Last universal ancestor: split between bacteria and archaea occurs as "tree of life" begins branching out – varieties of Eubacteria begin to radiate out globally. Fossils resembling cyanobacteria, found at Warrawoona, Western Australia.[citation needed] c. 3,480 Ma – Fossils of microbial mat found in 3.48 billion-year-old sandstone discovered in Western Australia.[11][12] First appearance of stromatolitic organisms that grow at interfaces between different types of material, mostly on submerged or moist surfaces. c. 3,460 Ma – Fossils of bacteria in chert.[citation needed] Zimbabwe Craton stabilizes from the suture of two smaller crustal blocks, the Tokwe Segment to the south and the Rhodesdale Segment or Rhodesdale gneiss to the north. c. 3.400 Ma – Eleven taxa of prokaryotes are preserved in the Apex Chert of the Pilbara craton in Australia. Because chert is fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrious material, it preserves small fossils quite well. Stabilization of Baltic Shield begins. c. 3.340 Ma – Johannesburg Dome forms in South Africa: located in the central part of Kaapvaal Craton and consists of trondhjemitic and tonalitic granitic rocks intruded into mafic-ultramafic greenstone – the oldest granitoid phase recognised so far. c. 3,300 Ma – Onset of compressional tectonics.[13] Intrusion of granitic plutons on the Kaapvaal Craton. c. 3,260 Ma – One of the largest recorded impact events occurs near the Barberton Greenstone Belt, when a 58 km (36 mi) asteroid leaves a crater almost 480 km (300 mi) across – two and a half times larger in diameter than the Chicxulub crater.[14] Mesoarchean Era Edit c. 3,200 Ma – Mesoarchean Era starts. Onverwacht series in South Africa form – contain some of the oldest microfossils mostly spheroidal and carbonaceous alga-like bodies. c. 3,200–2,600 Ma – Assembly of the Ur supercontinent to cover between 12 and 16% of the current continental crust. Formation of Limpopo Belt. c. 3,100 Ma – Fig Tree Formation: second round of fossilizations including Archaeosphaeroides barbertonensis and Eobacterium. Gneiss and greenstone belts in the Baltic Shield are laid down in Kola Peninsula, Karelia and northeastern Finland. c. 3,000 Ma – Humboldt Orogeny in Antarctica: possible formation of Humboldt Mountains in Queen Maud Land. Photosynthesizing cyanobacteria evolve; they use water as a reducing agent, thereby producing oxygen as a waste product. The oxygen initially oxidizes dissolved iron in the oceans, creating iron ore – over time oxygen concentration in the atmosphere slowly rises, acting as a poison for many bacteria. As Moon is still very close to Earth and causes tides 1,000 feet (305 m) high[citation needed], the Earth is continually wracked by hurricane-force winds – these extreme mixing influences are thought to stimulate evolutionary processes. Rise of Stromatolites: microbial mats become successful forming the first reef building communities on Earth in shallow warm tidal pool zones (to 1.5 Gyr). Tanzania Craton forms. c. 2,940 Ma – Yilgarn Craton of western Australia forms by the accretion of a multitude of formerly present blocks or terranes of existing continental crust. c. 2,900 Ma – Assembly of the Kenorland supercontinent, based upon the core of the Baltic shield, formed at c.3100 Ma. Narryer Gneiss Terrane (including Jack Hills) of Western Australia undergoes extensive metamorphism. Neoarchean Era Edit c. 2,800 Ma – Neoarchean Era starts. Breakup of the Vaalbara: Breakup of supercontinent Ur as it becomes a part of the major supercontinent Kenorland. Kaapvaal and Zimbabwe cratons join together. c. 2,770 Ma – Formation of Hamersley Basin on the southern margin of Pilbara Craton – last stable submarine-fluviatile environment between the Yilgarn and Pilbara prior to rifting, contraction and assembly of the intracratonic Gascoyne Complex. c. 2,750 Ma – Renosterkoppies Greenstone Belt forms on the northern edge of the Kaapvaal Craton. c. 2,736 Ma – Formation of the Temagami Greenstone Belt in Temagami, Ontario, Canada. c. 2,707 Ma – Blake River Megacaldera Complex begins to form in present-day Ontario and Quebec – first known Precambrian supervolcano – first phase results in creation of 8 km long, 40 km wide, east–west striking Misema Caldera* – coalescence of at least two large mafic shield volcanoes. c. 2,705 Ma – Major komatiite eruption, possibly global[13] – possible mantle overturn event. c. 2,704 Ma – Blake River Megacaldera Complex: second phase results in creation of 30 km long, 15 km wide northwest–southeast trending New Senator Caldera – thick massive mafic sequences which has been inferred to be a subaqueous lava lake. c. 2,700 Ma – Biomarkers of cyanobacteria discovered, together with steranes (sterols of cholesterol), associated with films of eukaryotes, in shales located beneath banded iron formation hematite beds, in Hamersley Range, Western Australia;[15] skewed sulfur isotope ratios found in pyrites show a small rise in oxygen concentration in the atmosphere;[16] Sturgeon Lake Caldera forms in Wabigoon greenstone belt – contains well preserved homoclinal chain of greenschist facies, metamorphosed intrusive, volcanic and sedimentary layers (Mattabi pyroclastic flow considered third most voluminous eruptive event); stromatolites of Bulawayo series in Zimbabwe form – first verified reef community on Earth. c. 2,696 Ma – Blake River Megacaldera Complex: third phase of activity constructs classic east-northeast striking Noranda Caldera which contains a 7-to-9-km-thick succession of mafic and felsic rocks erupted during five major series of activity. Abitibi greenstone belt in present-day Ontario and Quebec begins to form: considered world's largest series of Archean greenstone belts, appears to represent a series of thrusted subterranes. c. 2,690 Ma – Formation of high pressure granulites in the Limpopo Central Region. c. 2,650 Ma – Insell Orogeny: occurrence of a very high grade discrete tectonothermal event (a UHT metamorphic event). c. 2,600 Ma – Oldest known giant carbonate platform.[13] Saturation of oxygen in ocean sediments is reached as oxygen now begins to dramatically appear in Earth's atmosphere. Proterozoic Eon Phanerozoic Eon