era ... (geology) a length of time that is a division of an aeon; Word Origin mid 17th cent. Conformable: Definition. Mass extinctions lead to an increase in the rate of evolution . 1. a major division of geological time; an era is usually divided into two or more periods Familiarity information: GEOLOGICAL ERA used as a noun is very rare. How to use era in a sentence. (2013, updated) compilations. Eras are divisions of geologic time shorter than eons but longer than periods. The rocks under a specific area have a significant impact on how that land can best be used. The Carboniferous period, on the other hand, is named for the large coal beds that were formed during this time ("carboniferous" means coal-bearing). SEE PREVIOUS WORDS. ra (îr′ə, ĕr′ə) n. 1. 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. This process, performed by algae and other microorganisms, caused oxygen molecules in water to be released into the atmosphere. Ten eras are recognized by the International Union of Geological Sciences: the Eoarchean Era (4.0 billion to 3.6 billion years ago), the Paleoarchean Era (3.6 billion to 3.2 billion years ago), the Mesoarchean Era (3.2 billion to 2.8 billion years ago), the Neoarchean Era (2.8 billion to 2.5 billion years ago), the Paleoproterozoic Era (2.5 billion to 1.6 billion years ago), the Mesoproterozoic Era (1.6 billion to 1.0 billion years ago), the Neoproterozoic Era (1.0 billion to 541 million years ago), the Paleozoic Era (541 million to about 252 million years ago), the Mesozoic Era (roughly 252 million to 66 million years ago), and the Cenozoic Era (66 million years ago to the present). For example, the boundary between the Permian and the Triassic is marked by a global extinction where a large percentage of the world’s plant and animal species is eliminated. Instead, the length of time intervals is variable. During this period, the cooling of the Earth's crust allowed for the formation of the first oceans and continents. Quick word challenge. Oceans as we know them today did not appear until the Earth's crust began to cool many years later. The Cenozoic, Mesozoic, and Paleozoic are the Eras of the Phanerozoic Eon. Early humans, including Homo habilis, first appeared about 2.8 million years ago, and modern humans (Homo sapiens) first appeared about 300,000 years ago. A period of time characterized by particular circumstances, events, or personages: the Colonial era of US history; the Reagan era. 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. This eon is named after Hades, the Greek god of the underworld, and during this period the Earth was extremely hot. Retrieved from https://www.thoughtco.com/geologic-time-scale-eons-eras-periods-1440796. Geologic definition, of, relating to, or based on geology. Synonym Discussion of era. Eons and eras are larger subdivisions than periods while periods themselves may be divided into epochs and ages. Geologic dating is extremely imprecise. Term. Progressing from the oldest to the current, the four major eras of Earth's geological history are Precambrian, Paleozoic, Mesozoic and Cenozoic. It was the last period of the Precambrian's Neoproterozoic Era. Multicelled organisms first appeared during this time. The period of geologic time from about 540 million years to the present, including the Paleozoic, Mesozoic, and Cenozoic Eras. era ... (geology) a length of time that is a division of an aeon; Word Origin mid 17th cent. This last point in time is the start of a division of geological time called the Phanerozoic Eon. 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. an immeasurably or indefinitely long period of time : age; a very large division of geologic time usually longer than an era… How to use eon in a sentence. Scientists believe that the first single-celled lifeforms developed during the Archean. Please refer to the appropriate style manual or other sources if you have any questions. Geologic dating allows scientists to better understand ancient history, including the evolution of plant and animal life from single-celled organisms to dinosaurs to primates to early humans. Of course, these geologic units are not equal in length. William Smith, Jean d'Omlius d'Halloy, Georges Cuvier, and Alexandre Brogniart made efforts to identify strata using the fossils they contained in the early 19th century. the present era People feel much less secure in the present era of international terrorism. An important part of geology is the study of how Earth’s materials, structures, processes and organisms have changed over time. See more. This is a list of such named time periods as defined in various fields of study. 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. This eon is very distinct from the previous three—the Hadean, Archean, and Proterozoic—which are sometimes known as the Precambrian era. Human activity has transformed the planet; some scientists have proposed a new epoch, the "anthropocene," to describe this new period of life on Earth. Eras. How to use era in a sentence. The rocks formed during a period … Era definition is - a fixed point in time from which a series of years is reckoned. The dinosaurs were eventually wiped out during the K-2 Extinction, an event that killed about 75 percent of the life on Earth. We divide time into years, months, weeks, and days. Definition of era noun from the Oxford Advanced Learner's Dictionary. Phanerozoic means “visible life”, and is the time in which fossils are a… Unlike the Hadean, the Archean eon is divided into eras: the Eoarchean, Paleoarchean, Mesoarchean, and Neoarchean. This diagram is a wonderful representation of the age of the Earth from its creation, through the different geologic eras, and up to the present. These tiny microbes left their mark in layered rocks known as stromatolites, some of which are nearly 3.5 billion years old. 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. Werner championed the most significant attempt. This article was most recently revised and updated by, https://www.britannica.com/science/era-geologic-time, International Union of Geological Sciences. Learn more. A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. The few species that manage to survive after a mass extinction event have less competition for food, shelter, and sometimes even mates if they are one of the last individuals of their species still alive. The stratigraphic chart of geologic time. "Geologic Time Scale: Eons, Eras, and Periods." In the process, mammals diversified into the many species still present on the Earth today. This is a list of such named time periods as defined in various fields of study. Two or more geological eras form an Eon, which is the largest division of geologic time, lasting many hundreds of millions of years. Geology. Multicelled organisms first appeared during this time. A period of time as reckoned from a specific date serving as the basis of its chronological system. Prior to oxygenic photosynthesis, Earth's atmosphere had no free oxygen, a huge impediment to the evolution of life. An example of an era is the industrial era. It includes the study of organisms that have inhabited our planet. It also helps them learn more about how human activity has transformed the planet. Because of the difficulties involved in establishing accurate chronologies, the eras contained within Precambrian time (approximately 4.6 billion to 541 million years ago) are classified independently. ERA: Definition. geological era - a major division of geological time; an era is usually divided into two or more periods. An unconformity in which the strata below dip at an angle different from that of the beds above. Quick word challenge. Period, in geology, the basic unit of the geologic time scale; during these spans of time specific systems of rocks were formed. ThoughtCo. It includes the study of organisms that have inhabited our planet. This is the branch of earth sciences that deals with the concept of geological time and dating the sequence of events throughout the Earth’s history. (2020, August 27). More complex animals appeared in the oceans about 565 million years ago, and became much more common about 542 million years ago. geology: Geological eras ... SEE FULL DEFINITION. There are 22 defined periods. These are fossil bacteria, and for most of Earth history, life was simple. These creatures were the largest to ever walk the Earth. For example, the boundary between the Permian and the Triassic is marked by a global extinction where a large percentage of the world’s plant and animal species is eliminated. Question: 1 - Geologists refer to an eon as the largest subdivision of time on the geologic time scale. 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. Latest Word Submissions bougie Sep 30, 2020. culture war Sep 30, 2020. unreified Sep 30, 2020. friluftsliv Sep 29, 2020. geological period, period - a unit of geological time during which a system of rocks formed; "ganoid fishes swarmed … The geological clock: a projection of Earth’s 4,5 Ga history on a clock Author: Woudloper Derivative work: Hardwigg Wikipedia. The fossil forms that occur in the rocks, however, provide the chief means of establishing a…. Alden, Andrew. Geologic definition, of, relating to, or based on geology. Others believe it was a supercontinent known as Vaalbara. era - A division of geologic time of several hundred million years in duration. Life on Earth During the Precambrian Time Span, The Cenozoic Era (65 Million Years Ago to the Present), Prehistoric Life During the Permian Period, Overview of Dinosaurs and Prehistoric Animals of Kentucky, The Cambrian Period (542-488 Million Years Ago), Committee for the Geologic Map of the World, B.A., Earth Sciences, University of New Hampshire. The centerfold illustration from the popular USGS pamphlet "Geologic Time" is now available as a downloadable poster in both page-size and poster-size resolutions. Quiz Review. The enumeration of those geologic time units is based on stratigraphy, which is the correlation and classification of rock strata. Eons, eras, and periods are usually separated by a significant geologic event and are unique in their climate, landscape, and biodiversity. 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