Eon geologic time scale

Terms in this set (272) What is the category name for the largest division of time used on the geologic time scale? Eon. Why is the geologic time scale more detailed in the Phanerozoic than in previous eons? The Phanerozoic Eon is more detailed because of the presence of organisms with hard parts and the rapid increase in. biodiversity.

Eon geologic time scale. The scale is split into different units; An Eon is a period of time greater than half a billion years. Eons are split into smaller units called Eras which last several hundreds of millions of years. Eras are split into smaller again units known as Periods which are again split into smaller units called Epochs .

The geologic time scale provides geologists across the world with a shared reference of time. You might say that the geologic time scale is to geoscientists what the periodic table of elements is to chemists. The geologic time scale is divided into (from longest to shortest): eons, eras, periods, epochs and ages.

This clip illustrates many of the important events in the story of life on Earth. It also explains the Geologic Time Scale, which is the system used to ...January 1 12 am: Earth forms from the planetary nebula – 4600 million years ago. February 25, 12:30 pm: The origin of life; the first cells – 3900 million years ago. March 4, 3:39 pm: Oldest dated rocks – 3800 million years ago. March 20, 1:33 pm: First stromatolite fossils – 3600 million years ago. July 17, 9:54 pm: first fossil ...basic unit of the geologic time scale that's a subdivision of an era; can be divided into smaller units called epochs. epochs. the smallest unit of the geologic time scale; is a subdivision of a period. ... the three eras and meanings of the phanerozoic eon. 88. what percent of earth's history does the precambrian eon cover? triassic, jurassic ...Right around noon, the atmosphere becomes oxygen rich. By 1:00 pm (13:00 h) the single-celled eukaryotes have arrived. By 5:00 pm (17:00 h) the first multicellular forms appear. The first aquatic animals don't arrive until after 8:00 pm. Plants colonize land at 9:30 pm and land animals follow at 10:00 pm. The dinosaurs are the life of the party ...After completing the Geologic Time Scale lab, we now know that there were many eons, eras, and periods during Earth's history. The Earth was markedly different during each one of ... Hadean Eon Archean Eon Proterozoic Eon Cambrian Period Ordovician Period Silurian Period Devonian Period Carboniferous Period Permian Period Triassic PeriodGeologists 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.

Listing 1 represents the complete geologic time scale, though only the three eras of rank Eon are shown, along with descriptions of the two intermediate boundaries. An illustration of the finer decomposition of parts of the Phanerozoic and Late Permian is …The Precambrian was the first super eon of Earth's history. This division of time — about seven-eighths of Earth's history — lasted from the first formation of the planet (about 4.6 billion ...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.The Precambrian was the first super eon of Earth's history. This division of time — about seven-eighths of Earth's history — lasted from the first formation of the planet (about 4.6 billion ...Beginning ~2.5 BYA at the start of the Proterozoic eon, early cyanobacteria produce O2 as a byproduct of oxygenic photosynthesis in the oceans. The O2 is absorbed in oceans and seabed rock by reacting with soluble iron and precipitated iron oxide (rust) from the oceans, generating banded iron formations.Fossils & Geologic Time. Geologic time is the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins at the start of the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day.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 90% of Earth’s history. The last one, the Phanerozoic (meaning “visible life”), is the time that ...geologic time scale. time scale representing the history of Earth. era. second largest unit of geologic time, lasting tens to hundreds of millions of years and consisting of two or more periods. period. unit of geologic time that lasts tens of millions of years and is associated with a particular type of rock system. epoch.

Geologic Time ScaleIntroductionIn climate change studies many reference are made to the geologic record or geologic time. The geologic time scale is an internationally developed and agreed scheme of subdividing the passage of time since the origin of Earth. ... According to the modern geologic time scale, the Archean was the first eon, which ...Geologic Time Scale Activity Option 2: Procedures without materials There are many diverse types of models. A timeline is one way to represent the geologic time scale, but there are other ways as well. 1. Below Table 1, you have been provided with the geological time scale. The time scale is an approximation and is not to scale. 2.* Not recognized by ICS. The above timescale is a work in progress and will doubtless be modified with future discoveries and suggestions. For example John Laurie, Daniel Mantle and Robert S Nicoll, Customising the geological timescale note that the 2004 version of the Geological Time Scale is mainly built around northern hemisphere …The Geologic Column. Over the past 150 years detailed studies of rocks throughout the world based on stratigraphic correlation have allowed geologists to correlate rock units and break them into time units. The result is the geologic column (on next page), which breaks relative geologic time into units of known relative age.BOOKS – Preview of Geologic Time Scale 2020 (3) STRATIGRAPHIC GUIDE – a concise version of the official manual. (4) RESOURCES – including diagrams of inter-regional correlations , links to lexicons (national rock formations of Australia, Canada, NW Europe, Britain), “ GeoWhen ” database of historic and regional stage names, and …What is the geologic time scale. A timeline of earths history broken down into specific time intervals such as eons, eras, epochs, and life on earth. T/F: The precambrian represents a much longer part of earths history than the phanerozoic. true. Why do geologists know so little about precambrian history. There were fewer life forms during the ...

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And the system we use to bind all these chapters together is the Geologic Time Scale. First, let’s talk about the history of geologic time itself. ... And the earliest Eon is known as the Hadean.Eon. Phanerozoic - The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 541 million years to the present, and it began with the Cambrian Period when animals first developed hard shells preserved in the fossil record.Geologic time is first divided into eon s; these are the Hadean, Archean, Proterozoic, and Phanerozoic. The first three eons are often referred to as the Precambrian, which we'll call a "super" eon. ... Figure 3.24 - Geologic time scale from Cambrian to Triassic that shows fossil age ranges for Exercise 3.6. The age span for each type ...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.Geologic Time ScaleIntroductionIn climate change studies many reference are made to the geologic record or geologic time. The geologic time scale is an internationally developed and agreed scheme of subdividing the passage of time since the origin of Earth. ... According to the modern geologic time scale, the Archean was the first eon, which ...

Summary. Geologic Time Scale divisions mark major events which highlight changes in climate, geography, atmosphere, and life. The largest units of time are eons; the 4.6 billion years of earth’s history are divided into four eons. The Phanerozoic Eon includes the most recent 545 million years and the most detailed fossil record.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 is the largest division of time, followed by era, period, epoch, and age. January 1 12 am: Earth forms from the planetary nebula – 4600 million years ago. February 25, 12:30 pm: The origin of life; the first cells – 3900 million years ago. March 4, 3:39 pm: Oldest dated rocks – 3800 million years ago. March 20, 1:33 pm: First stromatolite fossils – 3600 million years ago. July 17, 9:54 pm: first fossil ... Geologic time is the billions of years since the planet Earth began developing. Scientists who study the structure and history of Earth are called geologists. Their field of study is called geology . Geologists study rocks and fossils , or remains of living things that have been preserved in the ground. The rocks and fossils tell the story of ...Question: Geologic 'Deep' Time A) Name the 3 Eras of the Geologic Time Scale that comprise the Phanerozoic Eon, and the duration dates of each era. (Oldest at the bottom). Name of the Era Date of each Boundary (Specify to the nearest million) 1. B) Name the 3 Periods of the Mesozoic Era of the Geologic Time Scale, and give the duration dates.What are the eons of the geologic time scale? Eons are the largest divisions of the geologic time scale. They cover time spans of millions to billions of …The Geologic Time Scale is divided into four classes of measured time. List in order from largest to smallest. Eons, Eras, Periods, Epochs. Study with Quizlet and memorize flashcards containing terms like List all Eons in order. (Oldest to Youngest), List all Eras in order (Oldest to Youngest), List all Eras in Archean Eon (Oldest to Youngest ...The largest time unit on the geologic time scale, next in order of magnitude above era. A unit in the geological time scale that is a subdivision of a period. A major division on the geologic time scale; eras are divided into shorter units called periods. The remains or traces of organisms preserved from the geologic past.The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 538.8 million years to the present, and it began with the Cambrian Period when animals first developed hard shells preserved in the fossil record.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. These units are called geochronologic units, (geo ...Homo sapiens evolve. Study with Quizlet and memorize flashcards containing terms like List the following units of geologic time in order from shortest to longest: eon, epoch, era, period, What are the 2 eons on the geologic time scale? Circle which one is longest., How old is the Earth? and more.The Proterozoic Eon is the most recent division of the Precambrian. It is also the longest geologic eon, beginning 2.5 billion years ago and ending 541 million years ago. It accounts for a little less than 4/9ths of geologic time. During the Proterozoic Eon, modern plate tectonics became active, and the ancient cores of the continents moved ...

A - Eon is the main division of the geologic time scale, distances hundreds to thousands of millions of years. 3. A - Phanerozoic Eon is the present geologic eon in the geologic time scale, and the one throughout which plentiful animal and plant life has occurred.

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 years ago. (Prior to that ...The geologic time scale is a type of "calendar" that organizes Earth's history on the basis of major events or changes that have occurred. The scale divides all geologic time into a series of named intervals or units according to the order in which rocks and fossils were formed. ... The Hadean Eon began about 4.6 billion years ago as ...Geological time has been divided into four eons: Hadean, Archean, Proterozoic, and Phanerozoic, and as shown in Figure 8.3, 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 most familiar with because Phanerozoic rocks are the most common on ...geologic time scale v. 6.0 cenozoic mesozoic paleozoic precambrian age epoch age picks magnetic period hist. chro n. polarity quater-nary pleistocene* holocene* calabrian gelasian c1 c2 c2a c3 c3a c4 c4a c5 c5a c6 c6a c6b c6c c7 c5b c5c c5d c5e c8 c9 c10 c7a c11 c12 c13 c15 c16 c17 c18 c19 c20 c21 c22 c23 c24 c25 c26 c27 c28 c29 c30 0.012 1.8 3 ...Oct 18, 2023 · The Geological time scale is segmented into eons such as Archean, Hadean, Proterozoic, and Phanerozoic. The initial three can be combined to be called the Precambrian supreon. The list of the eons has been presented here; check the complete details of the eons. Hadean Eon. In this eon of geological time scale, oxygen was not present. An eon is an immeasurable unit of time. One can say "an eon" or use any other word that would quantify an infinite, indeterminable period. An eon is any indefinite, very long period. In the ancient scriptures, eon is also said to be an archaic name for omnipotent beings like Gods. Eons are the largest time scale in the geologic timescale.The geological time scale is based on the the geological rock record, which includes erosion, mountain building and other geological events. Over hundreds to thousands of millions of years, continents, oceans and mountain ranges have moved vast distances both vertically and horizontally. For example, areas that were once deep oceans hundreds of ...

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The geologic time scale or geological time scale ( GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks).rocks on earth. These, with the Proterozoic Eon are called the Precambrian Eon. The remainder of geologic time, including present day, belongs to the Phanerozoic Eon. While the units making up the time scale are called geochronologic units, the actual rocks formed during those specific time intervals are called chronostratigraphic units.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. These units are called geochronologic units, (geo ...As you see in above time scale chart, its main components are (from largest to smallest): eons, eras, periods and epochs. Hadean. The Hadean eon, named after the Greek god and ruler of the underworld Hades, is the oldest eon from 4.54 to 4.0 billion years ago. This time represents the earliest earth characterized by a partially molten surface, volcanism, and asteroid impacts, including the one ...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.The following table shows the geologic time scale. Phanerozoic Eon. (544 million years ago - Present) The period of time, also known as an eon, between the end of the Precambrian and today, The Phanerozoic begins with the start of the Cambrian period, 544 million years ago. It encompasses the period of abundant, complex life on the Earth.This chronological time chart is broken into different time chunks, the largest being the Eon, then Era, Period, and Epoch. ... Geological time scale. Time chart. Multiple Choice. Edit. Please save your changes before editing any questions. 20 seconds. 1 pt. Approximately how old is the Earth? 4.6 billion years old. 4.6 million years old. 5 ...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 is ...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. ….

Study with Quizlet and memorize flashcards containing terms like All of geologic time prior to the beginning of the Paleozoic era is termed the Phanerozoic eon. [True / False], The geologic time scale was devised before numerical dating using radioactivity was invented. [True / False], What fundamental concept states that in a horizontal sequence of conformable sedimentary strata, each higher ...Mar 18, 2020 · Colors are used to indicate the age of rocks on geologic maps. There are two major color standards, the international standard and the U.S. Geological Survey standard. (All of the geologic time scales here are made using the 2009 standard of the Committee on the Geologic Map of the World.) English: Geologic time scale covering the Precambrian and Phanerozoic eons with detail down to the epoch. This image is in the public domain in the United States because it only contains materials that originally came from the United States Geological Survey, an agency of the United States Department of the Interior.23-Sept-2023 ... From origin to now, Earth's 4 eons are the Hadean, Archean, Proterozoic and Phanerozoic Eon. The Hadean, Archean and Proterozoic eons are ...The geologic time scale. Image by Jonathan R. Hendricks for the Earth@Home project. Note that the geologic time scale above is not scaled to time and mostly represents the Phanerozoic Eon. Mosts of geologic history (88%) happened during the Precambrian, which is represented by Hadean, Archean, and Proterozoic eons.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 Geologic Time Scale is an important vertical timeline. We will begin by exploring the Pre-Archaean, Archaean, Proterozoic and Phanerozoic, which are major divisions of the Geologic Time Scale. Click on each of the highlighted divisions to find out more. Let's explore further. Within the Phanerozoic, we see three major changes in biodiversity.the scale of a calendar year. When geologic time is compressed to the scale of a calendar year, 1 second equals about 146 years. At this scale, World War II began about 0.4 second before midnight on December 31; because of rounding, this is shown as midnight of the new year. On the back of this sheet is a chart showing Eon geologic time scale, “Eon,” also spelled as “aeon,” refers to the largest division of the geologic time scale, superseding eras. It signifies an indefinitely long period, often used to describe billion-year timescales in the field of geology and cosmology [1] ., The scale is further broken down into time periods which are explained below. 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., Cenozoic Era, third of the major eras of Earth's history, beginning about 66 million years ago and extending to the present. It was the interval of time during which the continents assumed their modern configuration and geographic positions and during which Earth's flora and fauna evolved toward those of the present., The Geologic Time Scale provides a framework for understanding the history of the Earth and the development of life on our planet. It is an important tool for geologists, paleontologists, and ..., (This begins with the Cambrian Period and moves forward in time; note that in this traditional mnemonic the Holocene Epoch is here thought of by its older name ..., Geologic Time Scale 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., Tertiary Period, former official interval of geologic time lasting from approximately 66 million to 2.6 million years ago. It is the traditional name for the first of two periods in the Cenozoic Era (66 million years ago to the present); the second is the Quaternary Period (2.6 million years ago to the present). The Tertiary has five principal subdivisions, called epochs, which from oldest to ..., Geological Time Scale - Download as a PDF or view online for free. ... The Geologic Time Scale ... Cryptozoic eon (Precambrian time) • Lasted from 540 million years ago to 4600 million years ago. • Oldest and longest (covers almost 90% of earth’s history) ..., Online exhibits: Geologic time scale. The Archean Eon and the Hadean. The Archean eon, which preceded the Proterozoic eon, spanned about 1.5 billion years and is subdivided into four eras: the Neoarchean (2.8 to 2.5 billion years ago), Mesoarchean (3.2 to 2.8 billion years ago), Paleoarchean (3.6 to 3.2 billion years ago), and Eoarchean (4 to 3.6 billion years ago).*, New time scale.—Since publication of a chart showing divisions of geologic time in the seventh edition of the USGS guide Suggestions to Authors (Hansen, 1991), no other time scale has been officially endorsed by the USGS. For consistent usage of time terms, the USGS Geologic Names Committee (GNC; see box for members) and, 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 period, often used to describe billion-year timescales in the field of geology and cosmology. , The time interval occupied by the geological history of the earth is known as the Geologic time. Or a system of chronological dating which classifies geological strata in time is known as the geological time scale. The geologic time is estimated to have started at the Archean Eon which was approximately 4.0 to 2.5 billion years ago., Fossils & Geologic Time. Geologic time is the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins at the start of the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day., “Eon,” also spelled as “aeon,” refers to the largest division of the geologic time scale, superseding eras. It signifies an indefinitely long period, often used to …, Geologic Time ScaleIntroductionIn climate change studies many reference are made to the geologic record or geologic time. The geologic time scale is an internationally developed and agreed scheme of subdividing the passage of time since the origin of Earth. ... According to the modern geologic time scale, the Archean was the first eon, which ..., Get help with your Geologic time scale homework. Access the answers to hundreds of Geologic time scale questions that are explained in a way that's easy for you to understand. ... Plants and animals first became established on land during the: A. early Proterozoic Eon B. Paleozoic Era C. late Proterozoic Eon D. Mesozoic Era E. Cenozoic Era ..., 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 geologic time scale divides Earth's history into intervals of time defined by major events or changes on Earth. 13 of 23. Divisions of Time. Largest unit of geologic time is an Eon. Precambrian Time = 90% of Earth History ..., To aid their studies, geologists developed what is known as the geologic time scale, which segments Earth's history into eons, eras, periods, epochs, and ages based on changes in Earth's biological and geological makeup. An eon is a half billion years or more, an era is several hundred million years, a period is 10-100 million years, an ..., The Geologic Time Scale is an important vertical timeline. We will begin by exploring the Pre-Archaean, Archaean, Proterozoic and Phanerozoic, which are major divisions of the Geologic Time Scale. Click on each of the highlighted divisions to find out more. Let's explore further. Within the Phanerozoic, we see three major changes in biodiversity., Terms in this set (20) Geological Time Scale (GTS) Calendar of Earth's long history. eon, era, period, epoch, age. List the following units of geologic time in order of relative length, from longest to shortest: age, eon, period, era, epoch. Precambrian Supereon. the unit of geological time that includes the Hadean, Archaen, and Protorozoic Eons., Jan 31, 2019 · The Precambrian Time Span is the earliest time period on the Geologic Time Scale. It stretches from the formation of the earth 4.6 billion years ago to around 600 million years ago and encompasses many Eons and Eras leading up to the Cambrian Period in the current Eon. , As you see in above time scale chart, its main components are (from largest to smallest): eons, eras, periods and epochs. Hadean. The Hadean eon, named after the Greek god and ruler of the underworld Hades, is the oldest eon from 4.54 to 4.0 billion years ago. This time represents the earliest earth characterized by a partially molten surface, volcanism, and asteroid impacts, including the one ..., 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 Mesozoic Era are, from oldest to ..., Quiet Time Can Just Tease People Particularly Men Dodging Spouses Ordering Chores (Reverse). To memorize the Epochs of Cenozoic Era: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Holocene (or Recent): Pretty Eager Old Men Play Poker Hard. Pigeon Egg Omelets Make People Puke Heartily. Put Eggs On My Plate Please Homer., Geological Time Scale - Download as a PDF or view online for free. Geological Time Scale - Download as a PDF or view online for free. Submit Search. Upload Login ... Cryptozoic eon (Precambrian time) • Lasted from 540 million years ago to 4600 million years ago. • Oldest and longest (covers almost 90% of earth's history). • simple ..., The geologic time scale is a standard timeline used to describe the age of rocks and fossils, and the events that formed them. It spans Earth's entire history and is typically divided into four principle divisions. The first of these, the Precambrian, extends from about 4.6 billion years ago to 541 million years ago., 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 Hadean Eon and followed by the Proterozoic.The Archean represents the time period from (millions of years ago). The Late Heavy Bombardment is hypothesized to overlap with the ..., The geologic time scale is a type of “calendar” that organizes Earth’s history on the basis of major events or changes that have occurred. ... The Hadean Eon began about 4.6 billion years ago as Earth began to form, and it extended to about 4.0 billion years ago., EXERCISE 1: CREATING A GEOLOGIC TIME SCALE Data Sheet Submit the video of you geologic time scale to your instructor along with this completed document. Exercise 1 Post-Lab Questions 1. List the major mass extinction events in age order and identify the age at each boundary., May 28, 2021 · The Phanerozoic Eon is the current eon in the geologic time scale. It began around 541 million years ago (mya), and encompasses Earth’s history from then to the present day. It represents around 12% of Earth’s total history. Preceding the Phanerozoic Eon was the Proterozoic Eon. The Phanerozoic Eon began with an event known as the Cambrian ... , 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 …, The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon.