Geologic time scale. Use the links in the "time machine" below and explore a specific period that interests you. Read more about the geologic time scale, its origins and its …Managing employee payroll can be a complex and time-consuming task for businesses of all sizes. From tracking hours worked to calculating salaries, there are numerous details to keep in mind.The geologic time scale is used by geologists and other scientists to map the timing and relationships between events that have occurred during the history of the Earth. Based on radiometric dating techniques, the Earth is estimated to be about 4,570 million years (4570 "Ma") old. The geological time scale is a means of mapping the history of ...Divisions of Geologic time ( part 2) Geological time begins with Precambrian , time ( era ). Precambrian. The Precambrian time covers approximately 88% of Earth's history. The four Eras. Precambrian - 88% of earth's history. Paleozoic (ancient life) - 544 million years ago and lasted 300 million years. Mesozoic (middle life) - 245 million years ...See full list on simple.wikipedia.org The National Park System contains a magnificent record of geologic time because rocks from each period of the geologic time scale are preserved in park landscapes. No single park has rocks from every geologic period, though some come close. Geologic Time. With the help of clocks, calendars, and appointment books, we organize our lives around time.In today’s fast-paced world, time management is essential for success. Whether you’re a solopreneur or part of a large team, efficient scheduling is key to keeping your work on track.Advantages of Simplified Geological Time Scale: Ease of Understanding: The simplified geological time scale provides a more accessible and easier-to …The geologic time scale is often shown with illustrations of how life on Earth has changed. It sometimes includes major events on Earth, too, such as the formation of the major mountains or the extinction of the dinosaurs. Figure 12.2 shows you a different way of looking at the geologic time scale. It shows how Earth's environment and life ...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 …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 ... Tertiary (/ ˈ t ɜːr. ʃ ə. r i, ˈ t ɜː r. ʃ i ˌ ɛr. i / TUR-shə-ree, TUR-shee-err-ee) is an obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start of the Cenozoic Era, and extended to the beginning of the Quaternary glaciation at …Sep 23, 2023 · Periods are divisions of geologic time longer than epochs but shorter than an era. Each period spans a length of tens to one hundred million years. Next, there are 34 defined epochs which generally last for tens of millions of years. The geologic time scale conceptually consists of periods that we break down into smaller epochs. Epochs On the Geologic Time Scale, the Cenozoic Era covers from approximately 66 million years ago to the present. On the Geological Time Scale, this period of time corresponds with the extinction of the dinosaurs and the rise of mammals. Which is why it was called the Cenozoic Era because this name means “new life” in Greek. Sep 23, 2023 · Periods are divisions of geologic time longer than epochs but shorter than an era. Each period spans a length of tens to one hundred million years. Next, there are 34 defined epochs which generally last for tens of millions of years. The geologic time scale conceptually consists of periods that we break down into smaller epochs. Epochs Geologic Time Scale: Divisions of Geologic Time approved by the U.S. Geological Survey Geologic Names Committee, 2010. The chart shows major chronostratigraphic and geochronologic units. It reflects ratified unit names and boundary estimates from the International Commission on Stratigraphy (Ogg, 2009). Map symbols are in parentheses.... simplified geologic time scale? Subdivision EonEraPeriodEpoch PhanerozoicCenozoicQuaternary2.58 MaHolocene11.7 Ka Pleistocene Neogene23 MaPliocene5.3 Ma ...Module 3b, FNJ 5, How do I create a simplified geologic time scale? Eon Era Period Epoch Time Phanerozoic Cenozoic Quaternary Holocene 11.7 Ka Pleistocene 2.58 Ma Neogene Pliocene 5.3 Ma Miocene Paleogene Oligocene 23.3 Ma Eocene 33.9 Ma Paleocene 56 Ma Mesozoic Cretaceous 66 Ma Periods are divisions of geologic time longer than epochs but shorter than an era. Each period spans a length of tens to one hundred million years. Next, there are 34 defined epochs which generally last for tens of millions of years. The geologic time scale conceptually consists of periods that we break down into smaller epochs. EpochsDownload scientific diagram | (A) Simplified geologic map of Washington State. (B) Time scale of geologic deposits and events for the Puget Lowland. from publication: 2. The Geology of Puget ...The geological time scale is currently maintained by the International Commission on Stratigraphy (ICS), which is part of the International Union of Geological Sciences. The …Module 3b, FNJ 5, How do I create a simplified geologic time scale? Eon Era Period Epoch Time Phanerozoic Cenozoic Quaternary Holocene 11.7 Ka Pleistocene 2.58 Ma Neogene Pliocene 5.3 Ma Miocene Paleogene Oligocene 23.3 Ma Eocene 33.9 Ma Paleocene 56 Ma Mesozoic Cretaceous 66 Maice age, also called glacial age, any geologic period during which thick ice sheets cover vast areas of land. Such periods of large-scale glaciation may last several million years and drastically reshape surface features of entire continents. A number of major ice ages have occurred throughout Earth history. The earliest known took place …Aug 25, 2023 · The geologic time scale pieces together the history of Earth like a “calendar”. It unifies on a single scale the period starting with the creation of the planet and the present moment. Your best friend’s birthday is next month. Your winter vacation starts next week, and you missed your dentist’s appointment yesterday. In this assignment, please unscramble the essential names and numbers provided in Figure 5 of the Geologic Time Scale module to create simplified Geologic Time Scale using figure 5. Make sure to: Neatly organize names and numbers in a table format. Include the proper hierarchy of divisions. Correctly spell geologic names. Image transcription text.Geochronology - Radioactive Dating, Isotopes, Applications: As has been seen, the geologic time scale is based on stratified rock assemblages that contain a fossil record. For the most part, these fossils allow various forms of information from the rock succession to be viewed in terms of their relative position in the sequence. Approximately the first 87 …Earth’s Timeline and History. 4,567,000,000 years ago, Earth was covered in molten lava. Earth was completely unrecognizable. In its earliest stage of formation, it was uninhabitable as it clumped from a cloud of dust. About 1,000,000,000 years ago, Earth had its first signs of life. Single-celled organisms consumed the sun’s energy.The modern Geologic Time Scale as shown above is a compendium of both relative and absolute age dating and represents the most up-to-date assessment of Earth's history. Using a variety of techniques and dating methods, geologists have been able to ascertain the age of the Earth, as well as major eras, periods, and epochs within Earth's history.The geologic time scale is used by geologists and other scientists to map the timing and relationships between events that have occurred during the history of the Earth. Based on radiometric dating techniques, the Earth is estimated to be about 4,570 million years (4570 "Ma") old. The geological time scale is a means of mapping the history of ...Dec 13, 2018 · All geologists use the same basic divisions of geologic time (e.g., eras and periods). The International Stratigraphic Chart (Grandstein and Ogg 2004; International Commission on Stratigraphy 2005) is the most accurate and up-to-date time scale available for worldwide correlation of rock units. The geologic time scale pieces together the history of Earth like a “calendar”. It unifies on a single scale the period starting with the creation of the planet and the present moment. Your best friend’s birthday is next month. Your winter vacation starts next week, and you missed your dentist’s appointment yesterday.7 oct 2016 ... Geologic Time Scale A BRIEF HISTORY OF EARTH SINCE 4.6 BILLION YEARS. 2. Measuring Time • The Geological time scale is a record of the life ...One way to distinguish and define each segment of time is by the occurrence of major geologic events and the appearance (and disappearance) of significant life-forms, starting with the formation of Earth's crust followed by the appearance of ever-changing forms of life on Earth.Determine the order of geologic events using relative dating principles. Calculate the age of rocks using numerical dating principles. Select correctly from the range of available numerical dating tools to access Earth history at different scales and in different materials. Explain how past events from geologic time influence the present and ...Geological time in one calendar year. Geologists have developed many metaphors to try to characterize the vastness of time separating important events in the history of Earth and its life. One of the most popular such metaphors scales this 4.54 billion year history into a familiar 365-day calendar year:2.5 billion – 541 million years ago. 20 cm. Phanerozoic. 541 million years ago – TODAY. 5.4cm. This would work great with easel paper but sticking paper together like we have worked just as well. Prepare a …And now that people have been around for the equivalent of 12 seconds, some geologists propose adding a new period to the Geologic Time Scale. It will mark the time since humans began altering Earth. Starting about 10,000 years ago, it is tentatively being called the Anthropocene. Its geologic layers will be quite a mix.Dec 13, 2018 · All geologists use the same basic divisions of geologic time (e.g., eras and periods). The International Stratigraphic Chart (Grandstein and Ogg 2004; International Commission on Stratigraphy 2005) is the most accurate and up-to-date time scale available for worldwide correlation of rock units. 3 may 2018 ... Our subjective division of time based on interpreting an incomplete fossil record may be irreproducible as a whole but the geologic time scale ...Earth’s history is divided into a hierarchical series of smaller chunks of time, referred to as the geologic time scale. These divisions, in descending length of time, are called eons, eras, periods, epochs, and ages. These units are classified based on Earth’s rock layers, or strata, and the fossils found within them. From examining these ...The geologic time scale is a timeline that shows the earth's history divided into time units based on the significant events occurring at that time. ... There is evidence of very simple, mostly ...... Geologic Time Scale 2004 3 5.5 Superchrons and polarity bias 86 1.2 How this book is arranged 4 5.6 Summary and conclusions 86 1.3 Conventions and standards ...Ordovician Chronostratigraphic Chart. Showing correlation of regional chronostratigraphic schemes with the new global stages and series for the Ordovician System. By Bergstrom, S.M., Xu Chen, Gutierrez-Marco, J.C., and Dronov, A., 2008, Lethaia, DOI 10.1111/j.1502-3931.2008.00136.x. Click HERE to download a better version (higher resolution)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).Fossils are fundamental to the geologic time scale. The names of most of the eons and eras end in zoic, because these time intervals are often recognized on the basis of animal life. Rocks formed during the Proterozoic Eon may have fossils of relative simple organisms, such as bacteria, algae, and wormlike animals.Detailed Description. This simplified geologic timescale shows the time before abundant life on Earth in black. The Phanerozoic, which began 541 million years ago, is in colored blocks, and is subdivided into the Paleozoic (colored green), Mesozoic (blue), and Cenozoic (yellow) Eras. For a more complete version of the Divisions of the …The geologic time scale is the “calendar” for events in Earth history. It subdivides all time into named units of abstract time …Walker, J.D., Geissman, J.W., Bowring, S.A., and Babcock, L.E., compilers, 2012, Geologic Time Scale v. 4.0: Geological Society of America, doi: 10.1130/2012.CTS004R3C. ©2012 The Geological Society of America. 237 70 80 90 100 110 120 130 140 150 160 170 180 190 210 200 220 230 240 250 5 10 15 20 25 30 35 40 45 50 55 60 65 750 1000 1250 1500 ...The geologic time scale is a timeline that shows the earth's history divided into time units based on the significant events occurring at that time. ... There is evidence of very simple, mostly ...The modern Geologic Time Scale as shown above is a compendium of both relative and absolute age dating and represents the most up-to-date assessment of Earth's history. Using a variety of techniques and dating methods, geologists have been able to ascertain the age of the Earth, as well as major eras, periods, and epochs within Earth's history.The Geologic time is very vast and wide. The Geological Time Scale was constructed using the evidences collected from a) Field observations b) Fossil records c) Stratigraphic correlations d ...Key Features. Provides the most detailed integrated geologic time scale available that compiles and synthesize information in one reference. Gives insights on the …The Geologic Time Scale is a tool for understanding how the Earth formed and came to be the way it is today. This is a simplified answer leaving much to be explained. Geologic time takes in all that has happened on earth since the Archaen Eon about 4 billion years ago. Informally it goes back to the Hadean 4.6 billion years ago. Aug 29, 2019 · The final time period on the Geologic Time Scale is the Cenozoic Period. With large dinosaurs now extinct, smaller mammals that had survived were able to grow and become dominant. The climate changed drastically over a relatively short period of time, becoming much cooler and drier than during the Mesozoic Era. 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.. Major volcanic events altering the Earth's environment and …epoch, unit of geological time during which a rock series is deposited.It is a subdivision of a geological period, and the word is capitalized when employed in a formal sense (e.g., Pleistocene Epoch). Additional distinctions can be made by appending relative time terms, such as early, middle, and late.The use of epoch is usually restricted to divisions of the …Aug 25, 2023 · The geologic time scale pieces together the history of Earth like a “calendar”. It unifies on a single scale the period starting with the creation of the planet and the present moment. Your best friend’s birthday is next month. Your winter vacation starts next week, and you missed your dentist’s appointment yesterday. The geologic timescale is continually being revised by new research and more accurate dating methods. When changes are proposed, the International …The geologic time scale is often shown with illustrations of how life on Earth has changed. It sometimes includes major events on Earth, too, such as the formation of the major mountains or the extinction of the dinosaurs. Figure 12.2 shows you a different way of looking at the geologic time scale. It shows how Earth's environment and life ...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. From longest to shortest in relative length, those units are ...The 3 major eras of geologic time between the Precambrian period and the present. Mass extinctions mark boundaries between eras. On the Geologic Time Scale, "Era" are subdivided into Periods; example: Mesozoic Era is subdivided into the Triassic, Jurassic and Cretaceous Periods. A distinct period of geological time.Simplified Geologic Time Scale. Era. Period or System. Epoch or Series. Cenozoic. (66 million years ago - Present) characterized by the emergence of the Himalayas (cooling, reduced CO 2 ) also, delineated by the K-T boundary. The Cascade Range began approximately 36 million years ago, with the major peaks appearing early to middle Pleistocene. Simplified Geologic Time Scale. Era, Period or System, Years. Contemporary eras. (1945 - present). Modern era. (2024 - present). January 1, 2024 - present.The National Park System contains a magnificent record of geologic time because rocks from each period of the geologic time scale are preserved in park landscapes. No single park has rocks from every geologic period, though some come close. Geologic Time. With the help of clocks, calendars, and appointment books, we organize our lives around time.Simplified Geologic Time Scale. Era. Period or System. Epoch or Series. Cenozoic. (66 million years ago - Present) characterized by the emergence of the Himalayas (cooling, reduced CO 2 ) also, delineated by the K-T boundary. The Cascade Range began approximately 36 million years ago, with the major peaks appearing early to middle Pleistocene. Feb 28, 2020 · The geologic time scale is a system used by scientists to describe Earth's history in terms of major geological or paleontological events (such as the formation of a new rock layer or the appearance or demise of certain lifeforms). Geologic time spans are divided into units and subunits, the largest of which are eons. Geological time scale. Fossils record the changes of life on earth, and are used to date rocks that were formed over the last 540 million years. This is a simplified version of the internationally-accepted time scale. Ages on the right (in millions of years) are based on radiometric dating. A much more detailed subdivision of the time scale has ... Mar 22, 2020 · All charts can be downloaded by clicking on the images. Geologic Time Scale 2012. Geologic Time Scale 2012 (Aug. 2012) Dimensions: 71 x 102 cm (28" x 40") This chart displays the International Divisions of Geologic Time, geomagnetics and sea-level changes and 10 paleogeographic maps. Poster can be downloaded, or send $10 for postage for up to 2 ... The modern geologic time scale was formulated in 1911 by Arthur Holmes. But ancient Greek philosophers like Xenophanes and Aristotle had put forth observations about rock beds, fossils, and changes in the positions of lands and seas. The geologic time scale is a way of representing deep time based on events that have occurred throughout …All geologists use the same basic divisions of geologic time (e.g., eras and periods). The International Stratigraphic Chart (Grandstein and Ogg 2004; International Commission on Stratigraphy 2005) is the most accurate and up-to-date time scale available for worldwide correlation of rock units.The geological time scale--shown above in a simplified form--is one of the crowning achievements of science in general and geology in particular. It is a reference and communication system for comparing rocks and fossils from throughout the world and is geology's equivalent of the periodic table of the elements.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).Activity Subject: Geologic time scale, creative expression of science concepts Grade Level: 6-8 grades Introduction In this culminating lesson, students view Ray Troll’s music video and artistic representation of the geologic time scale. They then are challenged to create their own artistic representation of the time scale in a medium of7.4.5 Geologic Time Scale. Geologic time on Earth, is 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.Earth’s Timeline and History. 4,567,000,000 years ago, Earth was covered in molten lava. Earth was completely unrecognizable. In its earliest stage of formation, it was uninhabitable as it clumped from a cloud of dust. About 1,000,000,000 years ago, Earth had its first signs of life. Single-celled organisms consumed the sun’s energy.Simplified Geologic Time Scale Era Period or System Epoch or Series Cenozoic (66 million years ago - Present) characterized by the emergence of the Himalayas (cooling, reduced CO 2 ) also, delineated by the K-T boundary The Cascade Range began approximately 36 million years ago, with the major peaks appearing early to middle Pleistocene.The geologic time scale pieces together the history of Earth like a “calendar”. It unifies on a single scale the period starting with the creation of the planet and the present moment. Your best friend’s birthday is next month. Your winter vacation starts next week, and you missed your dentist’s appointment yesterday.The Geologic Time Scale forms the foundation for thinking about the sequence of events in Earth's deep history. In this assignment, please unscramble the essential names and numbers provided in Figure 5 of the Geologic Time Scale module to create own simplified Geologic Time Scale for reference as a literate Geoscientist.A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and calibrated in years. Over the years, the development of new dating methods and refinement of previous ones have stimulated revisions to geologic time scales.Detailed geologic time scale: The United States Geological Survey has published "Divisions of Geologic Time: Major Chronostratigraphic and Geochronologic Units." It is a much more detailed time scale than the simplified scale shown above. Geologic time scale Take a journey back through the history of the Earth — jump to a specific time period using the time scale below and examine ancient life, climates, and geography. You might wish to start in the Cenozoic Era (65.5 million years ago to the present) and work back through time, or start with Hadean time (4.6 to 4 billion ...Anthropocene Epoch, unofficial interval of geologic time, making up the third worldwide division of the Quaternary Period (2.6 million years ago to the present), characterized as the time in which the collective activities of human beings (Homo sapiens) began to substantially alter Earth’s surface, atmosphere, oceans, and systems of nutrient ...Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay …Geologic Time Scale: Divisions of Geologic Time approved by the U.S. Geological Survey Geologic Names Committee, 2010. The chart shows major chronostratigraphic and geochronologic units. It reflects ratified unit names and boundary estimates from the International Commission on Stratigraphy (Ogg, 2009). Map symbols are in parentheses. Mar 25, 2021 · The geologic time scale is the “calendar” for events in Earth history.It subdivides all time into named units of abstract time called—in descending order of duration—eons, eras, periods, epochs, and ages. Oct 19, 2023 · Earth’s history is divided into a hierarchical series of smaller chunks of time, referred to as the geologic time scale. These divisions, in descending length of time, are called eons, eras, periods, epochs, and ages. These units are classified based on Earth’s rock layers, or strata, and the fossils found within them. From examining these ... May 2, 2018 · Without the geologic time scale it would be impossible to compare rocks made at the same time in Wales and the Czech Republic or North America to Russia. That earth scientists have achieved this ... May 26, 2021 · The geologic time scale is a means of measuring time based on layers of rock that formed during specific times in Earth’s history and the fossils present in each layer. The main units of the geologic time scale, from largest (longest) to smallest, are: eon, era, period, epoch and age. Each corresponds to the time in which a particular layer ... The geologic time scale is the “calendar” for events in Earth history. It subdivides all time into named units of abstract time called—in descending order of duration—eons, eras, periods, epochs, and ages.Detailed Description. This simplified geologic timescale shows the time before abundant life on Earth in black. The Phanerozoic, which began 541 million years ago, is in colored blocks, and is subdivided into the Paleozoic (colored green), Mesozoic (blue), and Cenozoic (yellow) Eras. For a more complete version of the Divisions of the Geologic ...
Module 3b-Field Notes Journal (FNJ) 5: How do I create a simplified geologic time scale? Subdivision Eon Era Period Epoch Phanerozoic Cenozoic Quaternar y 2.58 Ma Holocene 11.7 Ka Pleistocene Neogene 23 Ma Pliocene 5.3 Ma Miocene Paleogene 66 Ma Oligocene 33.9 Ma Eocene 56 Ma Paleocene Mesozoic Cretaceous 145 Ma. Zillow 37043
Geologic Time Scale. Simplified Geologic Time Scale. Names and dates extracted from the GSA Geologic Time Scale (2009 version) - see reference below. For a larger version, click here. For a very large version, click here. The U.S. Geological Survey released a revised timescale in 2010. The reference for the USGS timescale is:Geological Time Scale Life on the earth did not come into being with its birth. The earth has a long history and has seen many changes on her surface through different periods. The earth cooled from its ... prior to the Cambrian, very simple life forms such as algae, bacteria, fungi, sponges andThe modern geologic time scale was formulated in 1911 by Arthur Holmes. But ancient Greek philosophers like Xenophanes and Aristotle had put forth observations about rock beds, fossils, and changes in the positions of lands and seas. The geologic time scale is a way of representing deep time based on events that have occurred throughout …The Geologic Time Scale is a tool for understanding how the Earth formed and came to be the way it is today. This is a simplified answer leaving much to be explained. Geologic time takes in all that has happened on earth since the Archaen Eon about 4 billion years ago. Informally it goes back to the Hadean 4.6 billion years ago.Figure 7: Simplified accretionary history of British Columbia A Accretionary wedge. Volcanic arc Asthenosphere. D. Continental lithosphere. E. Oceanic lithosphere. F. Simulated terranes. 4. Using the geologic time scale in Figure 6, calculate approximately how many years it took in total to attach all of these terranes to the North American ... Andrew Alden Updated on February 28, 2020 The geologic time scale is a system used by scientists to describe Earth's history in terms of major geological or paleontological events (such as the formation of a new rock layer or the appearance or demise of certain lifeforms).Simplified Geologic Time Scale. Era. Period or System. Epoch or Series. Cenozoic. (66 million years ago - Present) characterized by the emergence of the Himalayas (cooling, reduced CO 2 ) also, delineated by the K-T boundary. The Cascade Range began approximately 36 million years ago, with the major peaks appearing early to middle Pleistocene.Module 3b-Field Notes Journal (FNJ) 5: How do I create a simplified geologic time scale? Subdivision Eon Era Period Epoch Phanerozoic Cenozoic Quaternar y 2.58 Ma Holocene 11.7 Ka Pleistocene Neogene 23 Ma Pliocene 5.3 Ma Miocene Paleogene 66 Ma Oligocene 33.9 Ma Eocene 56 Ma Paleocene Mesozoic Cretaceous 145 MaThe Meghalayan Age, which is the most recent subdivision of the Holocene Epoch, began about 4,200 years ago, at a time when agricultural societies around the world experienced a very abrupt, critical and significant drought and cooling. Last month, this Age was officially ratified as the most recent unit of the Geologic Time Scale.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, …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..