How long is an eon in geology

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 ...

How long is an eon in geology. Aug 11, 2020 · It would be a good idea to print a copy (in color) to put on your wall while you are studying geology. Geological time has been divided into four eons: Hadean (4570 to 4850 Ma), Archean (3850 to 2500 Ma), Proterozoic (2500 to 540 Ma), and Phanerozoic (540 Ma to present). As shown in Figure 8.1.2 8.1. 2, the first three of these represent almost ...

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 …

An eon (or aeon) is a term in Earth science for the longest periods of time. It describes a part of the Earth's existence lasting hundreds of millions to billions of years.. A geologic eon is part of Earth's existence, made up of a number of eras of different lengths. A geologic era is made up of two or more shorter times called geologic periods.A geologic period is, in turn made up of yet ...8 thg 5, 2001 ... ... eons. "Eon" also means any span of one billion years. 2nd Order, Erathem, Era, A geologic division including several periods, but smaller than ...Although the term aeon may be used in reference to a period of a billion years (especially in geology, cosmology and astronomy), its more common usage is for any long, indefinite period. Aeon can also refer to the four aeons on the geologic time scale that make up the Earth's history, the Hadean , Archean , Proterozoic , and the current aeon ... The Holocene epoch began about 12,000 years ago when Earth began warming after the last ice age. But according to Gill, the end of that ice age, even though it coincided with the transition to a ...Mesozoic Era, second of Earth’s three major geologic eras of Phanerozoic time. Its name is derived from the Greek term for “middle life.” The Mesozoic Era began 252.2 million years ago, following the conclusion of the Paleozoic Era, and ended 66 million years ago, at the dawn of the Cenozoic Era.(See the geologic time scale.)The major divisions of the …In Astronomy, an eon refers to 1 billion ( 109) years. But it also refers to a very long, unspecified period of time, or specific geologic stages of the Earth. Explanation: Since …Phanerozoic Eon, the span of geologic time extending about 541 million years from the end of the Proterozoic Eon (which began about 2.5 billion years ago) to the present. The Phanerozoic, the eon of visible life, is divided into three major spans of time largely on the basis of characteristic.The Archean Eon ( IPA: / ɑːrˈkiːən / ar-KEE-ən, also spelled Archaean or Archæan ), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth 's history, preceded by the Hadean Eon and followed by the Proterozoic. The Archean represents the time period from 4,000 to 2,500 Ma (millions of years ago).

11 thg 6, 2023 ... The Precambrian Eon is distinct in several ways, setting it apart from later geological eras. Length and Significance. The sheer length of the ...The Hadean is the first geologic eon in the history of the Earth. The name ... long ago (it has been estimated that the vast majority of water on Planet ...Ediacaran Period, also called Vendian Period, uppermost division of the Proterozoic Eon of Precambrian time and latest of the three periods of the Neoproterozoic Era, extending from approximately 635 million to 541 million years ago. The Ediacaran followed the Cryogenian Period (approximately 720 million to approximately 635 million years ago) and was …Geology is the study of earth, the materials of which it is made, the structure of those materials and the effects of the natural forces acting upon them and is important to civil engineering because all work performed by civil engineers in...The geologic time scale and basic outline of Earth’s history were worked out long before we had any scientific means of assigning numerical age units, like years, ... Geologic time has been subdivided into a series of divisions by geologists. Eon is the largest division of time, followed by era, period, epoch, and age.Precambrian - Ancient Life, Fossils, Eons: Precambrian rocks were originally defined to predate the Cambrian Period and therefore all life, although the term Proterozoic was later coined from the Greek for “early life.” It is now known that Precambrian rocks contain evidence of the very beginnings of life on Earth—which, based on the age of the rocks …Aug 11, 2023 · An eon does not have a specific span of years, but is generally recognized as being around 1000-years. It is a long span of geologic time. Eons are longer periods of time than eras.

Geological time has been divided into four eons: Hadean (4570 to 4850 Ma), Archean (3850 to 2500 Ma), Proterozoic (2500 to 540 Ma), and Phanerozoic (540 Ma to present). As shown in Figure 8.1.2, the first three of these represent almost 90% of Earth’s history. The last one, the Phanerozoic (meaning “visible life”), is the time that we are ...The Archean (formerly Archaeozoic) is a geologic eon between the Hadean and Proterozoic eons. The Archean Eon begins at roughly 3.8 billion years ago.The term Cenozoic, originally spelled Kainozoic, was introduced by English geologist John Phillips in an 1840 Penny Cyclopaedia article to designate the most recent of the three major subdivisions of the Phanerozoic Eon.Derived from the Greek for recent life, it reflects the sequential development and diversification of life on Earth from the …Figure 1.6.1 1.6. 1 image description: The Hadean eon (3800 Ma to 4570 Ma), Archean eon (2500 Ma to 3800 Ma), and Proterozoic eon (542 Ma to 2500 Ma) make up 88% of geological time. The Phanerozoic eon makes up the last 12% of geological time. The Phanerozoic eon (0 Ma to 542 Ma) contains the Paleozoic, Mesozoic, and Cenozoic eras.7.4.5 Geologic Time Scale. Geologic time on Earth, represented circularly, to show the individual time divisions and important events. Ga=billion years ago, Ma=million years ago. Geologic time has been subdivided into a series of divisions by geologists. Eon.“But people haven’t really been looking for graphite in zircons for very long,” says Bell. Additional research — and zircons — are needed to add certainty. The two large flecks (center and top right) are tiny bits of carbon embedded within a 4.1-billion-year-old zircon crystal.

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The Phanerozoic Eon represents the time during which the majority of macroscopic organisms — algae, fungi, plants and animals — lived. When first proposed as a division of geologic time, the beginning of the Phanerozoic (542.0 million years ago)* was thought to coincide with the beginning of life.The Proterozoic Eon, meaning “earlier life,” is the eon of time after the Archean eon and ranges from 2.5 billion years old to 541 million years old. During this time, most of the central parts of the continents had formed and the plate tectonic process had started. Photosynthesis (in organisms like stromatolites) had already been adding ... Stages 4 and 5 (0.85 Ga – present): Other O 2 reservoirs filled; gas accumulates in atmosphere. [1] The Great Oxidation Event ( GOE) or Great Oxygenation Event, also called the Oxygen Catastrophe, Oxygen Revolution, Oxygen Crisis or Oxygen Holocaust, [2] was a time interval during the Early Earth 's Paleoproterozoic era when the Earth's ...Eon definition, an indefinitely long period of time; age. See more.In Astronomy, an eon refers to 1 billion (1 0 9) years. But it also refers to a very long, unspecified period of time, or specific geologic stages of the Earth Explanation: Since this question is posted in Astronomy, I will assume that the answer of eon = 1 0 9 years is the most appropriate, however it is not the most common.Aug 11, 2023 · How long is an eon? In geology, an eon is an abritrary length of time having no specific length of age. An eon is the the category encompassing the largest periods of time in geologic history.an ...

Perhaps the most important Paleoclimatic indicators in the Precambrian geological record reside in sedimentary rocks interpreted as glacial deposits. Sedimentary rocks of the long Archean Eon contain only sparse evidence of glacial activity at about 2.9 Ga in South Africa and a few other locations.Aug 3, 2023 - "Eon," also spelled as "aeon," refers to the largest division of the geologic time scale, superseding eras. It signifies an indefinitely long ...May 20, 2011 · On the Reasons Why We Need A New Supereon. Dr. M May 19, 2011 Earth eon Geology Geozoic origns supereon time. The largest unit of defined geologic time is the supereon. Only one is defined, the Precambrian spanning from the formation of the Earth to right before life goes crazy in the Cambrian explosion (4.6 billion years ago to 542 million ... 8.3 Hadean Eon Geologic Time Scale with ages shown. Geoscientists use the geological time scale to assign relative age names to events and rocks, separating major events in Earth’s history based on significant changes as recorded in rocks and fossils. This section summarizes the most notable events of each major time interval.An eon does not have a specific span of years, but is generally recognized as being around 1000-years. It is a long span of geologic time. Eons are longer periods of time than eras.Geology. Eon, aeon: the longest division of geologic time, geological time; a geological age; the time of the physical formation and development of the earth (especially prior to human history ); also, the largest division of geologic time, defined as a unit of geological time equal to a billion years. Age; a very large division of geologic ...The four eons in turn are divided into eras, which are the second- largest divisions of geologic time. Eras are divided into periods, which are the third- ...In Astronomy, an eon refers to 1 billion (10*9) years. But it also refers to a very long, unspecified period of time, or specific geologic stages of the Earth. That the answer of eon = 10*9 (10 to the 9th degree) years is the most appropriate, however, it is not the most common. The term eon (or aeon) is frequently used as a term for a very ...Mesozoic Era, second of Earth’s three major geologic eras of Phanerozoic time. Its name is derived from the Greek term for “middle life.” The Mesozoic Era began 252.2 million years ago, following the conclusion of the Paleozoic Era, and ended 66 million years ago, at the dawn of the Cenozoic Era.(See the geologic time scale.)The major divisions of the …Geologists generally agree that there are two major eons: the Precambrian eon and the Phanerozoic eon. The Precambrian 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.

Well-identified events of this eon were the transition to an oxygenated atmosphere during the Paleoproterozoic; the evolution of eukaryotes via symbiogenesis; several global glaciations, which produced the 300 million years-long Huronian glaciation (during the Siderian and Rhyacian periods of the Paleoproterozoic) and the hypothesized Snowball ...

Eon: Two or more eras compose an Eon. This is the largest division of time, lasting hundreds of millions of years. Era: Two or more periods compose on Era. One Era is hundreds of millions of years in duration. Period: This is the basic unit of geologic time. A Period lasts tens of millions of years, which is the time it takes to While the Phanerozoic Eon looks longer than the rest, it merely spans ~539 million years (~12% of Earth's history), whilst the previous three eons collectively span ~3,461 million years (~76% of Earth's history). This bias toward the most recent eon is in part due to the relative lack of information about events that occurred during the first ... In Astronomy, an eon refers to 1 billion (1 0 9) years. But it also refers to a very long, unspecified period of time, or specific geologic stages of the Earth Explanation: Since this question is posted in Astronomy, I will assume that the answer of eon = 1 0 9 years is the most appropriate, however it is not the most common.Eon definition, an indefinitely long period of time; age. See more.Phanerozoic Eon, the span of geologic time extending about 541 million years from the end of the Proterozoic Eon (which began about 2.5 billion years ago) to the present. The Phanerozoic, the eon of visible life, is divided into three major spans of time largely on the basis of characteristic assemblages of life-forms: the Paleozoic (541 million …In Astronomy, an eon refers to 1 billion (10*9) years. But it also refers to a very long, unspecified period of time, or specific geologic stages of the Earth. That the answer of eon = 10*9 (10 to the 9th degree) years is the most appropriate, however, it is not the most common. The term eon (or aeon) is frequently used as a term for a very ...The Hadean is the first geologic eon of Earth and lies before the Archean. It began with the formation of the Earth about 4600 million years ago and ended as defined by the ICS 4,000 million years ago. The name “Hadean” comes from Hades, the ancient Greek god of the underworld due to the “hellish” conditions on Earth at the time: the ...A geon is a specified 100-million-year interval of geologic time, counted backward from the present. The geon scale can be likened to a ladder, each interval between rungs representing 100 million years. Geons are named for the leftmost part of the number representing age. For example, the Earth formed about 4550 million years ago, an event ... AboutTranscript. Earth's 4.6 billion-year history has distinct periods. Learn about the four eons - Hadean, Archean, Proterozoic, and Phanerozoic - and how they mark different stages …

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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.The term Anthropocene initially emerged from the Earth System science community in the early 2000s, denoting a concept that the Holocene Epoch has terminated as a consequence of human activities. First associated with the onset of the Industrial Revolution, it was then more closely linked with the Great Acceleration in industrialization …An eon, which is the longest unit of geologic time, is roughly one billion years long. The geologic time scale currently has four named eons: ... Geologic Time Scale. Today, the geologic time scale is divided into major chunks of time called eons. Eons may be further divided into smaller chunks called eras, and each era is divided into periods. Figure 12.1 shows you what the geologic time scale looks like. We now live in the Phanerozoic eon, the Cenozoic era, and the Quarternary period. How many eons were there? There are an estimated 11.8 billion years in the universe. Is an eon is longer than an era? Yes, an eon is longer than an era. What does eon mean in Hebrew? eon means “time” in Hebrew. What is the longest time division in geology? The most common time division in geology is the Proterozoic.Answer and Explanation: 1. Become a Study.com member to unlock this answer! Create your account. View this answer. The longest subdivision in geologic time is an eon.. An eon lasts roughly one billion years, although some are slightly longer. The first eon was the... See full answer below.Earth's history is long. How do scientists keep track of what happened when? ... The common Chaotian Eon of the planetary disk dust and rock assembly would split into separate planetary geology ...8.3 Hadean Eon Geologic Time Scale with ages shown. Geoscientists use the geological time scale to assign relative age names to events and rocks, separating major events in Earth’s history based on significant changes as recorded in rocks and fossils. This section summarizes the most notable events of each major time interval.The Precambrian is an informal unit of geologic time, subdivided into three eons (Hadean, Archean, Proterozoic) of the geologic time scale. The Phanerozoic Eon is the most recent eon and began more than 500 million years ago. Phanerozoic- 538.8 to 0 million years ago. Proterozoic- 2,500 to 538.8 million years ago.An eon is a billion years in geology. An eon can also be defined as a gigaannum. After that comes a terrannum (1 trillion years) and so on in accordance with the SI prefix system. What is current eon? The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has …The Archean Eon (IPA: / ɑːr ˈ k iː ə n / ar-KEE-ən, also spelled Archaean or Archæan), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth's history, preceded by the … ….

The Precambrian Super Eon started about 4.56 billion years ago and ended about 541 million years ago. It can be divided into 3 specific Eons which are the Hadean, the Archean and the Proterozoic. Super Eons:Super Eons contain several Eons in them and cover extremely large periods of time.Major changes in earth’s physical and biological history stretch over several millions of years and hence in GTS all the divisions are expressed in ‘million years (mya – million years ago).’. The primarily defined divisions of time are eons, the Hadean, the Archean, the Proterozoic and the Phanerozoic. The first three of these can be ...... eons in order of increasing age. The names of the eras in the Phanerozoic eon (the eon of visible life) are the Cenozoic ("recent life"), Mesozoic ("middle ...This walk is through the Phanerozoic Eon, or the most recent 541 million years of geologic time, where fossil evidence of complex, abundant life is found. Life was much more primitive before the Phanerozoic Eon (the more than 4 billion years known as the Precambrian, and shown in black below) and is not represented in the Trek Through Time.While the Phanerozoic Eon looks longer than the rest, it merely spans ~539 million years (~12% of Earth's history), whilst the previous three eons collectively span ~3,461 million years (~76% of Earth's history). This bias toward the most recent eon is in part due to the relative lack of information about events that … See more13 thg 9, 2023 ... There are only four eons in Earth's history: the Hadean, Archean, Proterozoic, and Phanerozoic. Era: A division of an eon, representing tens to ...Best Answer. The oldest eon of geologic time is the Archaean Eon of the Precambrian period. The oldest rocks and fossils date from this time, about 3.8 to 2.5 billion …2. Proterozoic (2.5-0.542 billion years ago) The Proterozoic Eon extended between 2.5 billion years and 0.542 billion years ago. It is subdivided into the three eras of Paleoproterozoic, Mesoproterozoic, and Neoproterozoic. This eon witnessed some significant and exciting events in the history of the Earth. The first stable continents …Humans subdivide time into useable units such as our calendar year, months, weeks, and days; geologists also subdivide time. They have created a tool for measuring geologic time, breaking it into useable, understandable segments. For the purposes of geology, the “calendar” is the geologic time scale.During the Archean Eon, which spanned from approximately 4 billion to 2.5 billion years ago, significant geological and biological events unfolded on Earth. Notably, this eon witnessed the formation of the first continents, the development of Earth’s early atmosphere, and the emergence of life in the form of simple, single-celled organisms ... How long is an eon in geology, Mar 8, 2020 · Earth's history is long. How do scientists keep track of what happened when? ... The common Chaotian Eon of the planetary disk dust and rock assembly would split into separate planetary geology ... , Answer and Explanation: 1. Become a Study.com member to unlock this answer! Create your account. View this answer. The Phanerozoic Eon is the geological period that means ''visible life'' and it began around 545 million years ago and is the current eon, as of 2019,... See full answer below., The Proterozoic Eon, meaning “earlier life,” is the eon of time after the Archean eon and ranges from 2.5 billion years old to 541 million years old. During this time, most of the central parts of the continents had formed and the plate tectonic process had started. Photosynthesis (in organisms like stromatolites) had already been adding ..., 7.4.5 Geologic Time Scale. Geologic time on Earth, represented circularly, to show the individual time divisions and important events. Ga=billion years ago, Ma=million years ago. Geologic time has been subdivided into a series of divisions by geologists. Eon., The geologic time scale and basic outline of Earth’s history were worked out long before we had any scientific means of assigning numerical age units, like years, to events of Earth’s history. ... Geologic time has been subdivided into a series of divisions by geologists. Eon is the largest division of time, followed by era, period, epoch ..., In Astronomy, an eon refers to 1 billion (1 0 9) years. But it also refers to a very long, unspecified period of time, or specific geologic stages of the Earth Explanation: Since this question is posted in Astronomy, I will assume that the answer of eon = 1 0 9 years is the most appropriate, however it is not the most common., Eon, a long period of geologic time. Eons are the longest periods of geologic time in formal usage (eras are the second-longest). The Phanerozoic Eon (extending from the present to the beginning of the Cambrian Period), the Proterozoic Eon, and the Archean Eon are the three accepted eons. Informally, an eon is a period of one billion years., But the road to geological storage is long: ... Evolutionary eons are from ref. 1: the eon of biological innovation witnessed the evolution of the major metabolic pathways, ..., 23 thg 4, 2023 ... The Geologic Time Scale is divided into several large units of time, including eons, eras, periods, and epochs, and it provides a framework for ..., – An eon is the largest geological time unit, spanning hundreds of millions ... – Many geologists refer to the first three eons collectively as the ..., Eons. Eons, or Eonothems, are the largest division of time, lasting thousands of millions of years. There eons are: the Phanerozoic (current eon) and the Precambrian eons of …, The study of rocks is known as geology. Scientists who study rocks are known as geologists. There are several subdivisions of geology, with different designations for researchers who study the individual disciplines., MS-ESS1-4: Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth’s 4.6-billion-year-old history. This unit emphasizes the analysis of fossils contained in rock formations to establish relative ages of major events in Earth’s history., Precambrian - Ancient Life, Fossils, Eons: Precambrian rocks were originally defined to predate the Cambrian Period and therefore all life, although the term Proterozoic was later coined from the Greek for “early life.” It is now known that Precambrian rocks contain evidence of the very beginnings of life on Earth—which, based on the age of the rocks …, Precambrian Time. Learn more about the period that occurred 4.5 billion to 542 million years ago. Precambrian time covers the vast bulk of the Earth's history, starting with the planet's creation ..., In Astronomy, an eon refers to 1 billion (1 0 9) years. But it also refers to a very long, unspecified period of time, or specific geologic stages of the Earth Explanation: Since this question is posted in Astronomy, I will assume that the answer of eon = 1 0 9 years is the most appropriate, however it is not the most common., The Paleozoic (IPA: /ˌpæli.əˈzoʊ.ɪk,-i.oʊ-, ˌpeɪ-/ PAL-ee-ə-ZOH-ik, -⁠ee-oh-, PAY-; or Palaeozoic) Era is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of the Mesozoic Era., An era in geology is a time of several hundred million years. It describes a long series of rock strata which geologists decide should be given a name. An example is the Mesozoic era, when dinosaurs lived on the Earth. An era is made up of periods, and several eras make up an eon. How long is a supereon? Explanation: An eon consists of a ..., This walk is through the Phanerozoic Eon, or the most recent 541 million years of geologic time, where fossil evidence of complex, abundant life is found. Life was much more primitive before the Phanerozoic Eon (the more than 4 billion years known as the Precambrian, and shown in black below) and is not represented in the Trek Through Time., Many scientists define this time in the planet’s history by the scale of human influence, and label it as a new geological epoch called the Anthropocene. As of 2005, humans had built so many dams that nearly six times as much water was held in storage as flowed freely in rivers. ... There has been a long-standing narrative of humanity and ..., The Cenozoic, Mesozoic, and Paleozoic are the Eras of the Phanerozoic Eon. Names of units and age boundaries usually follow the Gradstein et al. (2012), Cohen et al. (2012), and Cohen et al. (2013, updated) compilations. Numerical age estimates and picks of boundaries usually follow the Cohen et al. (2013, updated) compilation., Eons :Eons are the largest intervals of geologic time and are hundreds of millions of years in duration. In the time scale above you can see the Phanerozoic Eon ..., Aug 3, 2023 - "Eon," also spelled as "aeon," refers to the largest division of the geologic time scale, superseding eras. It signifies an indefinitely long ..., For a breakdown on how these time intervals are chosen and organized, see An Introduction to Geology: Chapter 7. 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. Figure 2.3.2 2.3. 2: Artist’s impression of the Earth in the Hadean. , The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or paleontological events., MS-ESS1-4: Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth’s 4.6-billion-year-old history. This unit emphasizes the analysis of fossils contained in rock formations to establish relative ages of major events in Earth’s history., During the Archean Eon, which spanned from approximately 4 billion to 2.5 billion years ago, significant geological and biological events unfolded on Earth. Notably, this eon witnessed the formation of the first continents, the development of Earth’s early atmosphere, and the emergence of life in the form of simple, single-celled organisms ..., The geologic time scale is divided into several magnitudes of units of time: [1] Eons, or Eonothems, are the largest division of time, lasting thousands of millions of years. There eons are: the Phanerozoic (current eon) and the Precambrian eons of the Proterozoic, Archean, and Hadean. Eras, or Erathems, are the subdivisions of eons., 2. Proterozoic (2.5-0.542 billion years ago) The Proterozoic Eon extended between 2.5 billion years and 0.542 billion years ago. It is subdivided into the three eras of Paleoproterozoic, Mesoproterozoic, and Neoproterozoic. This eon witnessed some significant and exciting events in the history of the Earth. The first stable continents began to ..., In other words, one can say that a single eon is equivalent to about 1 billion years. The word “eon” is derived from the ancient Greek eon, meaning, in effect, “unlimited time.” The term “eon” does not refer to a specific length of time in years or decades. However, many use words like zillion and quadrillion to compare lengths., IPA guide Other forms: eons An eon is a really, really, super-long, impossible-to-measure length of time. If you sit down to dinner hanging your head and moaning that it's been an eon since …, Is An Era Longer Than A Eon? In geology, an era is a division of the geologic time scale that is longer than an eon but shorter than a period. The Paleozoic Era, for example, lasted from about 541 million years ago to 251 million years ago. How Long Is A Supereon? A supereon is an astronomical term used to describe a group of multiple eons. , Eons are the longest division of geologic time. Generally, we measure eons as billions of years ago (Ga) and millions of years ago (Ma). Geologists divide the lifespan of …