Cryogenian: The middle period in the Neoproterozoic Era: 635-720 Ma. Tonian: the earliest period of the Neoproterozoic Era: 720-1000 Ma. Mesoproterozoic: the middle era of the Proterozoic Eon, 1000-1600 Ma. Corresponds to "Precambrian Y" rocks of older North American stratigraphy. Paleoproterozoic: oldest era of the Proterozoic Eon, 1600-2500 ...Organization. In the geologic time scale, the youngest ages are on the top and the oldest on the bottom. The time scale is based upon relative times, therefore there aren’t any specific times listed with each era. The timescale is divided into eons, each eon into eras, each era into periods, and each period into epochs. Apr 16, 2022 · This era lasted from the formation of the earth about 4.5 billion years ago to the start of the Paleozoic era… Which of the following shows the correct order of geologic time scale from the longest to the shortest time interval? From longest to shortest, the segments of time are eon, era, period, and epoch. 5. 6. Archeozoic Eon (Archean) 3.9 to 2.5 billion years ago--"Ancient Life" - The first life forms evolve - one celled organisms. Blue-green algae, archaeans, and bacteria appear in the sea. This begins to free oxygen into the atmosphere. Hadean Eon 4.6 to 3.9 billion years ago--"Rockless Eon" - The solidifying of the Earth's continental and oceanic ...Figure 8.3.1 8.3. 1: Geologic Time Scale with ages shown. The Hadean Eon, named after the Greek god and ruler of the underworld Hades, is the oldest eon and dates from 4.5-4.0 billion years ago. This time represents Earth's earliest history, during which the planet was characterized by a partially molten surface, volcanism, and asteroid ...eon; era; period; epoch; age; chron . Subdivisions are termed ‘early’, ‘mid’ or ‘late’. Chronostratigraphy is similar, but is concerned with the relationships between time and the rocks deposited within those time intervals. Chronostratigraphical terms are applied to rocks deposited during specific intervals of time. eon > era > period. Which geologic era are we living in? Cenozoic. In which geologic era did the dinosaurs exist? Mesozoic. Which geologic time period lasted for ...The Precambrian was originally defined as the era that predated the emergence of life in the Cambrian Period. It is now known, however, that life on Earth began by the early Archean and that fossilized organisms became more and more abundant throughout Precambrian time. The two major subdivisions of the last part of the Precambrian are …A period of 1,000,000,000 years. Era. The longest division of geologic time, made up of one or more periods. Eon. (geology) The longest geochronologic unit, being a period of hundreds of millions of years; subdivided into eras. Era. A time period of indeterminate length, generally more than one year. ADVERTISEMENT. 03-May-2023 ... Then we have an era, which is smaller than an eon, but larger than a period. An era represents a time scale of around 60 to several. hundred ...c. 4,533 Ma – The Precambrian (to c. 539 Ma), 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 …Hadean Eon, informal division of the Precambrian occurring between about 4.6 billion and about 4.0 billion years ago. It was the time …Eons, eras, periods and epochs. Karl has been Purch's infographics specialist across all editorial properties since 2010.The Devonian (/ d ɪ ˈ v oʊ n i. ən, d ɛ-/ də-VOH-nee-ən, deh-) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, 419.2 million years ago (), to the beginning of the Carboniferous, 358.9 Ma. It is named after Devon, England, where rocks from this period were first studied.. The first significant …Answer: period<era<eon. Explanation: I took the test, sadly got a 70%.The geologic time scale (GTS) is a system of chronological dating that relates geological strata (stratigraphy) to time, and is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships of events that have occurred during Earth's history. Rise of humans, earliest writing in c. 3200 B.C., human ...Time Words: Era, Epoch, and Eon. An epoch, (not to be confused with epic ), like an era, is a period of time. An epoch is longer than an era and can cover more than one lifetime. It is marked by some significant development or series of developments: the feudal epoch, the epoch of exploration. An eon is a very long time indeed.Terminologi. Ada beberapa istilah yang menjelaskan skala atau rentang waktu geologi. Secara berturut-turut, skala waktu geologi dari yang paling besar hingga paling kecil yaitu eon (kurun), era (masa), periode/zaman, epoch, dan age/sub-kala.. Eon pertama adalah Hadean, ketika Bumi dan bulan terbentuk, yang berlangsung 600 juta tahun hingga …This is the Geological Time-Scale. The Geological Time-Scale is hierarchical, consisting of (from smallest to largest units) ages, epochs, periods, eras and eons. Each era, lasting many tens or hundreds of millions of years, is characterized by completely different conditions and unique ecosystems. For example, dinosaurs only lived during the ...What is eon era period and age epoch? Epochs are the smallest divisions. Many epochs make up a period, many periods make up an era, and many eras make up an eon. In defining the boundaries between major divisions, we often use markers, like the dinosaur extinction or the appearance of certain organisms.The Precambrian was originally defined as the era that predated the emergence of life in the Cambrian Period. It is now known, however, that life on Earth began by the early Archean and that fossilized organisms became more and more abundant throughout Precambrian time. The two major subdivisions of the last part of the Precambrian are …what are the eras? 541 mya-present. 1) Paleozoic. 2) Mesozoic. 3) Cenozoic. Paleozoic Era. -origin and initial diversification of animals, land plants, and fungi. -land animals first appear. -ends with the obliteration of almost all multicellular life forms at the end of the Permian period. Hadean Eon, informal division of the Precambrian occurring between about 4.6 billion and about 4.0 billion years ago. It was the time of Earth's initial formation—the accretion of dust and gases, collisions with larger bodies, the stabilization of its core and crust, and the rise of its atmosphere and oceans.The U.S. House Oversight Committee is probing a collection of period tracking apps and data brokers in light of emerging concerns about how private health data might be weaponized in the dawning post-Roe v. Wade era. The committee issued le...This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. See Answer. Question: Which of the following answers arranges the time periods listed in the correct order from LONGEST to SHORTEST? Stage, Era, Period Era, Period, Stage Stage, Period, Era Period, Stage, Era Era, Stage ...The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same. B) The mass number of the daughter isotope is one more than the parent, and both isotopes have the same atomic number. C) The daughter isotope has an atomic number two less than the parent and a mass number four less.eon, era, period, epoch. Assume that man's recorded history can be stretched back to 4600 years before the present. This is approximately what fraction of geologic time?An eon can be considered the same as a kalpa in Sanskrit. Eon is also the longest period of time as per geology, which explains why an eon is subdivided into eras. An era is another unit of measuring a specific period of time, basically in historical contexts. An era denotes a long period of time, but not longer than an eon.Verified questions. The atmosphere of Mars is mostly CO_ {2} C O2 (molar mass 44.0 g/mol) under a pressure of 650 Pa, which we shall assume remains constant. In many places the temperature varies from 0.0^ {\circ} \mathrm {C} 0.0∘C in summer to -100^ {\circ} C −100∘C in winter. Over the course of a Martian year, what are the ranges of (a ... Consider the names of the eras in the geologic timescale what is meant by zoic. Life living things. Who is credited with formulating the doctrine of uniformitarianism. ... Eon, era, period, epoch. Assume that man's recorded history can be stretched back to 4600 years before the present this is approximately what fraction of geologic time.Archeozoic Eon (Archean) 3.9 to 2.5 billion years ago--"Ancient Life" - The first life forms evolve - one celled organisms. Blue-green algae, archaeans, and bacteria appear in the sea. This begins to free oxygen into the atmosphere. Hadean Eon 4.6 to 3.9 billion years ago--"Rockless Eon" - The solidifying of the Earth's continental and oceanic ... The Devonian (/ d ɪ ˈ v oʊ n i. ən, d ɛ-/ də-VOH-nee-ən, deh-) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, 419.2 million years ago (), to the beginning of the Carboniferous, 358.9 Ma. It is named after Devon, England, where rocks from this period were first studied.. The first significant …24 mar 2023 ... ... period. Though she did, at times, lean into this persona, fans ... Swift stands atop a raised stage during the Reputation era of the concert.Much later within the eon, Pangea broke up into the seven continents we now have. The Phanerozoic eon is most famous for having two ice ages. There were also records of mass extinctions during this time. Eras. Eons are subdivided into Eras. There are 10 eras, the oldest being the Eoarchean Era that ranged from 4.0 billion to 3.6 billion years ago.Oct 5, 2023 · The Cambrian explosion was a sharp and sudden increase in the rate of evolution. About 538.8 million years ago, at the onset of the Cambrian Period, intense diversification resulted in more than 35 new animal phyla; however, new discoveries show that the “explosion” started roughly 575 million years ago, near the end of the Proterozoic Eon (2.5 billion to 538.8 million years ago), with the ... Apr 12, 2017 · An "eon" is the largest interval of hundreds million years ago. It is also classified as a long period of geographic time. Eons are subdivided into "eras". Eons are divided into smaller time intervals known as eras. In the frame, the Phanerozoic is divided into three eras: Cenozoic, Mesozoic and Paleozoic. Very significant events in Earth's ... The period is the basic unit of geological time in which a single type of rock system is formed. Two or more periods comprise a geological Era. Two or more Eras form an Eon, the largest division of geologic time. Some periods are divided into epochs. The major periods in the geologic history of the Earth are (mya=million years ago): EON. Eons are divided into eras, which are further divided into periods, epochs, and ages. Geologic dating is extremely imprecise. For example, although the date listed for the beginning of the Ordovician period is 485 million years ago, it is actually 485.4 with an uncertainty (plus or minus) of 1.9 million years. What Is Geologic Dating?The Cryogenian (from Ancient Greek: κρύος, romanized: krýos, meaning "cold" and γένεσις, romanized: génesis, meaning "birth") is a geologic period that lasted from It forms the second geologic period of the Neoproterozoic Era, preceded by the Tonian Period and followed by the Ediacaran.. The Cryogenian was a time of drastic biosphere changes.era, period, epoch, eon b. eon, epoch, period, era c. eon, era, period, epoch d. eon, era, epoch, period c (there are very few fossils preserved in Precambrian rocks) One important reason we do not know much about the geologic history of the Precambrian is that ________.A period of 1,000,000,000 years. Era. The longest division of geologic time, made up of one or more periods. Eon. (geology) The longest geochronologic unit, being a period of hundreds of millions of years; subdivided into eras. Era. A time period of indeterminate length, generally more than one year. ADVERTISEMENT.The Paleozoic Era. The Cambrian Period: Following the Precambrian mass extinction, there was an explosion of new kinds of organisms in the Cambrian Period (544–505 million years ago).Many types of primitive animals called sponges evolved. Small ocean invertebrates called trilobites became abundant.. Two representatives of more than fifty modern animal …Feb 22, 2022 · The Phanerozoic Eon covers 541 million years and includes three major geological eras: the Paleozoic, Mesozoic and, Cenozoic. Three definitions for Eon are: 1. An indefinitely long period of time ... Intervals of geological time are given formal names and grouped into a hierarchy according to their length (in decreasing time intervals):. eon; era; period ...04-Oct-2023 ... However, there is no information about eras or periods at the beginning of Precambrian eon. So, the only solution possible which can start with ...The Precambrian was originally defined as the era that predated the emergence of life in the Cambrian Period. It is now known, however, that life on Earth began by the early Archean and that fossilized organisms became more and more abundant throughout Precambrian time. The two major subdivisions of the last part of the Precambrian are …Eon, era, period, epoch. Assume that man's recorded history can be stretched back to 4600 years before the present this is approximately what fraction of geologic time. An eon can be considered the same as a kalpa in Sanskrit. Eon is also the longest period of time as per geology, which explains why an eon is subdivided into eras. An era is another unit of measuring a specific period of time, basically in historical contexts. An era denotes a long period of time, but not longer than an eon.- A scale that subdivides the 4.5-billion-year history of Earth into many different units and provides a meaningful time frame within which the events of the geologic past are arranged. EON. ERA. PERIOD. EPOCH. PHANEROZOIC. CENOZOIC. QUATERNARY. HOLOCENE. PLEISTOCENE. TERTIARY. PLIOCENE.Anthropology. Anthropology questions and answers. 1. Explain how fossils are formed and why they are not equally prevalent in all areas (3pts) 2. Define the terms eon era, period, and epoch and specify modern humans' place in geologic time. (3pts) 3. Compare 1 relative dating method with 1 absolute dating method.The precambrian era, or Supereon, refers to the geological time comprising the eons that came before the Phanerozoic eon. This time spans from the formation of Earth around 4.5 billion years ago to the evolution of abundant macroscopic hard-shelled animals, which marked the beginning of the Cambrian era, the first period of the first era of the …The Archean Eon was preceded by the Hadean Eon, an informal division of geologic time spanning from about 4.6 billion to 4 billion years ago and characterized by Earth’s initial formation. Records of Earth’s primitive atmosphere and oceans emerge in the earliest Archean (Eoarchean Era). Fossil evidence of the earliest primitive life-forms ...Overview. The Proterozoic eon (2500-542 mya) comprises three geologic eras, from oldest to youngest: . Paleoproterozoic era (2500-1600 mya) Mesoproterozoic era (1600-1000 mya) Neoproterozoic era (1000-542 mya); The Paleoproterozoic era is an interval of 900 million years during which the continents first stabilized, eukaryotic (nucleated) cells developed, …Evolution is the significant process. Geological time scale represents the major eon, era, periods and epoch. It tells us how the earth had been continued wi...Proterozoic eon (2500 - 542 MYA) Stromalites increased in diversity throughout the Proterozoic eon. This type of rock, consisting of silicified stromatolites, preserves microfossils of microbes. stromatolite chert. The time period from 635 to 542 MYA is called the ________ period. This period saw the origin and diversification of soft-bodied ...Geologic time scale with proportional representation of eons/eonothems and eras/erathems. Cenozoic is abbreviated to Cz. The image also shows some notable events in Earth's history and the general evolution of life. A megannus (Ma) represents one million (10 6) years. Alternate representation of the geologic time scale represented as a clock.Railroads struggled during the Great Depression, as did the rest of the nation. Read about railroads of the Depression era and the New Deal. Advertisement The period between 1930 and 1945 was a time of contrast and change. The railroad indu...Hadean Eon, informal division of the Precambrian occurring between about 4.6 billion and about 4.0 billion years ago. It was the time …As of April 2022 there are currently ten defined eras/erathems, namely the Eoarchean, Paleoarchean, Mesoarchean, Neoarchean, Paleoproterozoic, Mesoproterozoic, Neoproterozoic, Paleozoic, Mesozoic and Cenozoic, with none from the Hadean eon. A period is a major rank below an era and above an epoch. Study with Quizlet and memorize flashcards containing terms like What is the category name for the largest division of time used on the geologic time scale?, Why is the geologic time scale more detailed in the Phanerozoic than in previous eons?, The Jurassic Period lies in the _____ Era, which was dominated by large terrestrial vertebrates, or _____. and more. Explanation: Answer link. We live in the Holocene Epoch, of the Quaternary Period, in the Cenozoic Era (of the Phanerozoic Eon).Standard 8-2.4: Recognize the relationship among the units—era, epoch, and period—into which the geologic time scale is divided. Eons: Longest subdivision; based on the abundance of certain fossils Eras: Next to longest subdivision; marked by major changes in the fossil record Periods: Based on types of life existing at the timeFirst eukaryotes (single-celled algae): 1.4 billion years old. ... originate 3.5 billion years ago. ... HADEAN EON 3,800- No life known. Cooling and solidifying of ...eon era bdy. ages (ma) 1000 1200 1800 2050 2300 1400 1600 2500 2800 3200 3600 4000 541 635 720 period ediacaran cryogenian tonian stenian ectasian calymmian statherian orosirian rhyacian siderian neopro-terozoic mesopro-terozoic paleopro-terozoic neoarchean meso-archean paleo-archean eoarchean hadean 260 280 300 320 340 380 360 400 420 440 460 ... As of April 2022 there are currently ten defined eras/erathems, namely the Eoarchean, Paleoarchean, Mesoarchean, Neoarchean, Paleoproterozoic, Mesoproterozoic, Neoproterozoic, Paleozoic, Mesozoic and Cenozoic, with none from the Hadean eon. A period is a major rank below an era and above an epoch. that there are two major eons: the Precambrian eon and the Phanerozoic eon. Precambrian eon. goes from the formation of the earth to the time when multicellular organisms first appeared - that's a really long time - from 4,500 million years ago to just about 543 million years ago. Phanerozoic eon. which continues up to today.How are geologic time periods divided? In the Geologic Time Scale, time is generally divided on the basis of the earth’s biotic composition, with the Phanerozoic Eon (i.e. the Paleozoic, Mesozoic and Cenozoic Eras) representing the period of Earth’s history with advanced life forms, and the Pre Cambrian (or Proterozoic and Hadean Eras) …The Devonian (/ d ɪ ˈ v oʊ n i. ən, d ɛ-/ də-VOH-nee-ən, deh-) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, 419.2 million years ago (), to the beginning of the Carboniferous, 358.9 Ma. It is named after Devon, England, where rocks from this period were first studied.. The first significant adaptive radiation of life on ...Eonothem / Eon Erathem / Era GSSP age (Ma) Eonothem / Eon Erathem / Era System / Period Series / Epoch Stage / Age GSSP Eonothem / Eon Erathem / Era Series / Epoch Stage / Age GSSP GSSA INTERNATIONAL CHRONOSTRATIGRAPHIC CHART International Commission on Stratigraphy Colouring follows the Commission for the …Cryogenian: The middle period in the Neoproterozoic Era: 635-720 Ma. Tonian: the earliest period of the Neoproterozoic Era: 720-1000 Ma. Mesoproterozoic: the middle era of the Proterozoic Eon, 1000-1600 Ma. Corresponds to "Precambrian Y" rocks of older North American stratigraphy. Paleoproterozoic: oldest era of the Proterozoic Eon, 1600-2500 ...Geologic time, the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins with the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day. Modern geologic time scales also include the Hadean Eon (4.6 billion to 4.0 billion years ago). The history of the earth is broken up into a hierarchical set of divisions for describing geologic time. As increasingly smaller units of time, the generally accepted divisions are eon, era, period, epoch, age. In the time scale shown at left, only the two highest levels of this hierarchy are represented. The Phanerozoic Eon is shown along the ...Geologic time scale with proportional representation of eons/eonothems and eras/erathems. Cenozoic is abbreviated to Cz. The image also shows some notable events in Earth's history and the general evolution of life. A megannus (Ma) represents one million (10 6) years. Alternate representation of the geologic time scale represented as a clock.Mesozoic – The Mesozoic Era, also called the Age of Reptiles and the Age of Conifers, is the second-to-last era of Earth’s geological history, lasting from about 252 to 66 million years ago and comprising the Triassic, Jurassic and Cretaceous Periods. Occurred: 251.902 (+/- 0.24) million years ago – 65 million years ago.The Precambrian includes approximately 90% of geologic time. It extends from 4.6 billion years ago to the beginning of the Cambrian Period (about 539 Ma).It includes the first three of the four eons of Earth's prehistory (the Hadean, Archean and Proterozoic) and precedes the Phanerozoic eon.Eon, Long span of geologic time. In formal usage, eons are the longest portions of geologic time (eras are the second-longest). Three eons are recognized: the Phanerozoic Eon (dating from the present back to the beginning of the Cambrian Period), the Proterozoic Eon, and the Archean Eon. LessArcheozoic Eon (Archean) 3.9 to 2.5 billion years ago--"Ancient Life" - The first life forms evolve - one celled organisms. Blue-green algae, archaeans, and bacteria appear in the sea. This begins to free oxygen into the atmosphere. Hadean Eon 4.6 to 3.9 billion years ago--"Rockless Eon" - The solidifying of the Earth's continental and oceanic ... As such, the Phanerozoic Eon includes the Paleozoic Era , the Mesozoic Era , and ... Era; Quaternary Period; Silurian Period; Tertiary Period; Triassic Period.Many epochs make up a period, many periods make up an era, and many eras make up an eon. In defining the boundaries between major divisions, we often use markers, like the dinosaur extinction or ...Many epochs make up a period, many periods make up an era, and many eras make up an eon. In defining the boundaries between major divisions, we often use markers, like the dinosaur extinction or ...The Triassic Period is part of the Mesozoic Era and Phanerozoic Eon. The Triassic period has 3 epochs and 7 ages. Each of these shorter divisions of time identifies a notable event or characteristic feature based on its record. The Triassic period started 252 million years ago after Earth’s largest extinction event in history.Feb 15, 2017 · In general, an eon is a very long time, comparable to the age of the universe. An epoch is a fixed point in time (like the zero date of a calendar, or the moment a world-changing event occurred), especially one that marks the beginning of a new era. One can “make an epoch” by doing something that changes things forever. 8.6: Paleozoic. Figure 8.6.1 8.6. 1: The trilobites had a hard exoskeleton and were an early arthropod, the same group that includes modern insects, crustaceans, and arachnids. The Phanerozoic eon is the most recent eon and represents time in which fossils are common, 541 million years ago to today.
Geologic time, the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins with the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day. Modern geologic time scales also include the Hadean Eon (4.6 billion to 4.0 billion years ago).. Literacy definition education
In the Geologic Time Scale, time is generally divided on the basis of the earth’s biotic composition, with the Phanerozoic Eon (i.e. the Paleozoic, Mesozoic and Cenozoic Eras) representing the period of Earth’s history with advanced life forms, and the Pre Cambrian (or Proterozoic and Hadean Eras) representing the …10 oct 2016 ... La Tierra, tan vieja que medimos su edad en eones. Todos tenemos claro que un eón es un largo, larguísimo periodo de tiempo ...The period is the basic unit of geological time in which a single type of rock system is formed. Two or more periods comprise a geological Era. Two or more Eras form an Eon, the largest division of geologic time. Some periods are divided into epochs. The major periods in the geologic history of the Earth are (mya=million years ago):Mar 15, 2021 · eon = The largest unit of time. era = A unit of time shorter than an eon but longer than a period. period = A unit of time shorter than an era but longer than epoch. epoch = A unit of time shorter than a period but longer than an age. Archean = “Ancient” eon from 4,500 Mya – 2,500 Ma. The Precambrian chronometric scheme used for Eon, Era and System/Period boundaries is based purely on round-number chronometric divisions and ignores geology ...Generally, the eras used to describe the modern Earth are the Quaternary geological era and the Cenozoic evolutionary era. In the future, there may also be a historical era that the current time period, the 21st century, will belong to.--Eogalactic Period - 13550-13200 MYA. --Neogalactic Period - 13200-4680 MYA. -Neoproteimeran Era - 4680-4568 MYA. --Nephelean Period - 4680-4630 MYA. -- ...Lived exclusively during the Mesozoic Era. Animals that have hair and produce milk for their young; evolved during the Mesozoic Era but became dominant during the Cenozoic Era. Study with Quizlet and memorize flashcards containing terms like Geological Time Scale (GTS), eon, era, period, epoch, age, Precambrian Supereon and more.04-Oct-2023 ... However, there is no information about eras or periods at the beginning of Precambrian eon. So, the only solution possible which can start with ...18-Jul-2018 ... Geologists split periods of Earth's history into different chunks of time. Early Earth is categorised by the Hadean eon, but as soon as ...Classifying time To make geologic time easier to comprehend, geologists divided the 4.6 billion years of Earth’s history into units of time called eons. Then they further divided the eons into two or more eras, eras into two or more periods, periods into two or more epochs, and epochs into two or more ages.The 1960s to Modern Era in American section covers all the major events in modern American history. Learn about the 1960s to modern era in America. Advertisement The 1960s was a period in American history that was marked with conflict and s...Terminologi. Ada beberapa istilah yang menjelaskan skala atau rentang waktu geologi. Secara berturut-turut, skala waktu geologi dari yang paling besar hingga paling kecil yaitu eon (kurun), era (masa), periode/zaman, epoch, dan age/sub-kala.. Eon pertama adalah Hadean, ketika Bumi dan bulan terbentuk, yang berlangsung 600 juta tahun hingga …Archean Eon, also spelled Archaean Eon, the earlier of the two formal divisions of Precambrian time (about 4.6 billion to 541 million years ago) and the period when life first formed on Earth.Geological Time Scale infographic diagram including EON ERA period epoch age and features for geology science education and earth layers history table ...Geologic time is divided according to two scales. The more well-known of these is the geologic scale, which divides time into named groupings according to six basic units: eon, era, period, epoch, age, and chron. In addition, the chronostratigraphic scale identifies successive layers of rock with specific units of time.Labeled earth history scheme with epoch, era, period, EON and mass extinctions diagram. Educational inforgraphic with examples, explanation and description. Designers Also Selected These Stock Illustrations. Sadhu (holy man) from India. Geochronological scale.The Hadean (IPA: / h eɪ ˈ d iː ə n, ˈ h eɪ d i ə n / hay-DEE-ən, HAY-dee-ən) [] is the first and oldest of the four known geologic eons of Earth's history.It started with the planet's formation about 4.54 Bya, now defined as (4567.30 ± 0.16) Mya set by the age of the oldest solid material in the Solar System found in some meteorites about 4.567 billion years old. .