The colors were specified by the Committee for the Geologic Map of the World in 2009. geologic time, geological time the time of the physical formation and development of the earth (especially prior to human history) the Victorian era see thesaurus at period COLLOCATIONS ADJECTIVES/NOUN + era a new era The talks signalled a new era of cooperation between the two countries. These time intervals are not equal to the length of the hour in a day. An important part of geology is the study of how Earth’s materials, structures, processes and organisms have changed over time. ... Cenozoic Era: Definition. ThoughtCo, Aug. 27, 2020, thoughtco.com/geologic-time-scale-eons-eras-periods-1440796. geology: Geological eras ... SEE FULL DEFINITION. era ... (geology) a length of time that is a division of an aeon; Word Origin mid 17th cent. The Geologic Time Scale is the history of the Earth broken down into four spans of time marked by various events, such as the emergence of certain species, their evolution, and their extinction, that help distinguish one era from another. For example, the Paleozoic, Mesozoic, and Cenozoic eras are within the Phanerozoic Eon. 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. The fossil forms that occur in the rocks, however, provide the chief means of establishing a…. During the Ordovician period, fish, cephalopods, and corals first appeared; over time, these creatures eventually evolved into amphibians and dinosaurs. The first multicellular organisms developed during the Proterozoic eon, including early forms of algae. Originally, the sequential nature of defining periods was a relative one, originating from the superposition of corresponding stratigraphic sequences and the evidence Most of them were aquatic; the most famous examples are trilobites, small arthropods (creatures with exoskeletons) whose distinct fossils are still being discovered today. GEOLOGIC EONS, ERAS and PERIODS The period is the basic unit of geological time in which a single type of rock system is formed. How to use era in a sentence. geological period, period - a unit of geological time during which a system of rocks formed; "ganoid fishes swarmed … In the process, mammals diversified into the many species still present on the Earth today. Mass extinctions lead to an increase in the rate of evolution . This eon is named after Hades, the Greek god of the underworld, and during this period the Earth was extremely hot. The next geologic eon, the Archean, began about 4 billion years ago. Oceans as we know them today did not appear until the Earth's crust began to cool many years later. Let us know if you have suggestions to improve this article (requires login). We've arranged the synonyms in length order so that they are easier to find. Era definition is - a fixed point in time from which a series of years is reckoned. This is a list of such named time periods as defined in various fields of study. Geologists refer to an eon as the largest subdivision of time on the geologic time scale. Geologic definition, of, relating to, or based on geology. ra (îr′ə, ĕr′ə) n. 1. The Carboniferous period, on the other hand, is named for the large coal beds that were formed during this time ("carboniferous" means coal-bearing). Two or more geological eras form an Eon, which is the largest division of geologic time, lasting many hundreds of millions of years. Human activity has transformed the planet; some scientists have proposed a new epoch, the "anthropocene," to describe this new period of life on Earth. an immeasurably or indefinitely long period of time : age; a very large division of geologic time usually longer than an era… The categorization of the past into discrete, quantified named blocks of time is called periodization. It includes the study of organisms that have inhabited our planet. Quiz Review. Era definition is - a fixed point in time from which a series of years is reckoned. Term. "Geologic Time Scale: Eons, Eras, and Periods." Omissions? era ... (geology) a length of time that is a division of an aeon; Word Origin mid 17th cent. Eons and eras are larger subdivisions than periods while periods themselves may be divided into epochs and ages. The Ediacaran Period lasted about 50 million years, from 600 million years ago to about 542 million years ago. Data from Geologic Time Scale of 2015. The rocks formed during a period … An era is composed of one or more geological periods. The Proterozoic was also the period in which the Earth's first glaciers formed. View More Submit. The geologic time scale (GTS) is a system of chronological dating that classifies geological strata (stratigraphy) in time.It is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships of events in geologic history. For the purposes of geology, the “calendar” is the geologic time scale. Following the Mesozoic era was the Cenozoic, which began about 66 million years ago. The rocks under a specific area have a significant impact on how that land can best be used. The Proterozoic eon began about 2.5 billion years ago and ended about 500 million years ago when the first complex lifeforms appeared. Epochs are subdivisions of geologic periods, often chosen to correspond to a stratigraphic series. During the Mesozoic era, which began about 250 million years ago, dinosaurs ruled the planet. the present era People feel much less secure in the present era of international terrorism. Synonym Discussion of era. The definition of an era is a period of time in history that is unified by cultural or historical factors. Eons are divided into eras, which are further divided into periods, epochs, and ages. Eras are divisions of geologic time shorter than eons but longer than periods. geological era - a major division of geological time; an era is usually divided into two or more periods. "Geologic Time Scale: Eons, Eras, and Periods." Scientists believe that the first single-celled lifeforms developed during the Archean. Eras. Likewise, geologists created the geologic time scale to organize Earth’s history into eons, eras, periods, and epochs. The categorization of the past into discrete, quantified named blocks of time is called periodization. The Cenozoic Era (also Cænozoic, Caenozoic or Cainozoic; meaning “new life”, from Greek καινός kainos “new”, and ζωή zoe “life”) is the current and most recent of the three Phanerozoic geological eras, following the Mesozoic Era and covering the period from 66 million years ago to the present. The dinosaurs were eventually wiped out during the K-2 Extinction, an event that killed about 75 percent of the life on Earth. This last point in time is the start of a division of geological time called the Phanerozoic Eon. With the help of clocks, calendars, and appointment books, we organize our lives around time. SEE PREVIOUS WORDS. a major division of geologic time composed of a number of periods. The Anthropocene--the proposed name for our current geological epoch, one that designates the contemporary moment as one where human activity is the defining and dominant geological force on Earth--has served as a philosophical lightning rod. See GEOLOGICAL TIME. Question: 1 - Periods. 3. Geologic Time Frames Geological time frames are a way of referencing different time periods within the entire geological history of the earth. ThoughtCo. Some scientists even believe that during the Neoproterozoic era, about 650 million years ago, the surface of the Earth became frozen. A period of time as reckoned from a specific date serving as the basis of its chronological system. Ring in the new year with a Britannica Membership. How to use era in a sentence. The geologic time scale (GTS) is a system of chronological dating that classifies geological strata (stratigraphy) in time.It is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships of events in geologic history. The lengths of these eras are often measured by the term "mya," which represents "millions of years ago." The first significant attempt to construct a geologic time scale applicable anywhere on earth was made towards the end of the 18th century. (2013, updated) compilations. Multicelled organisms first appeared during this time. Modern geologic time scales additionally often include the Hadean Eon, which is an informal interval that extends from about 4.6 billion years ago (corresponding to Earth’s initial formation) to 4.0 … Definition. Geology is the study of Earth -- the materials that make it up, the processes that act on those materials, and the history of the planet and its life forms. an immeasurably or indefinitely long period of time : age; a very large division of geologic time usually longer than an era… These enormous changes to life on Earth have taken place over a period of time that, compared to geologic history, is relatively small. Eras encompass major intervals of Time and are defined based on the fossil life-forms found in the rock layers, and the Law of Superposition. Conformable: Definition. 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