File Name: geological time scale and evolution of life .zip
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 time scale was developed through the study of physical rock layers and relationships as well as the times when different organisms appeared, evolved and became extinct through the study of fossilized remains and imprints.
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This clock representation shows some of the major units of geological time and definitive events of Earth history. The informal Hadean eon represents the time before fossil record of life on Earth, its upper boundary is now regarded as 4. Other subdivisions reflect the evolution of life; the Archean and Proterozoic are both eons, the Paleaozoic, Mesozoic and Cainozoic are eras of the Phanerozoic eon. The two million year Quaternary period, the time of recognizable humans, is too small to be visible at this scale. The geologic time scale is a chronologic schema or idealized model relating stratigraphy to time that is used by geologists , paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth.
Earth has existed for 4. In that time, it has undergone amazing transformations as a variety of geologic processes have changed the planet. Have students read the introduction to the infographic. Timelines are sometimes used on maps to give a better idea of how time relates to the data or theme represented. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
Absolute age dating — 3. Geological maps. The geological time scale. Image by Jonathan R. 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.
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The divisions of the geologic time scale are organized stratigraphically, with the oldest at the bottom and youngest at the top. What similarities does it share with the time scale above? This is because older rocks have been buried deeply, intensely deformed and severely modified by long-term earth processes. The time scale is continuously being updated as we learn more about the timing and nature of past geological events. The ages and names of major geological time Periods and Eras are shown.
Geologic time , the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins at the start of the Archean Eon 4. Modern geologic time scales additionally often include the Hadean Eon , which is an informal interval that extends from about 4. It subdivides all time into named units of abstract time called—in descending order of duration— eons , eras , periods , epochs , and ages. The enumeration of those geologic time units is based on stratigraphy , which is the correlation and classification of rock strata.
The BGS geological timechart provides colourful reference material for use in schools, colleges and at home, setting out the geological timescale and geochronological terms we use at BGS. You can browse the timechart by geological Era in the page below or download the Phanerozoic Timechart as a pdf.
As above, this time scale is based on the International Commission on Stratigraphy. Quaternary Ice Age recedes, and the current interglacial begins. Younger Dryas cold spell occurs, Sahara Desert forms from savannah, and agriculture begins, allowing humans to build cities. Cultures continue to grow in complexity and technical advancement through the Iron Age BC , giving rise to many pre-historic cultures throughout the world, eventually leading into Classical Antiquity, such as Ancient Rome and even to the Middle Ages and present day. Also refer to the List of archaeological periods for clarification on early cultures and ages. Evolution of anatomically modern humans. Quaternary Ice Age continues with glaciations and interstadials and the accompanying fluctuations from to ppmv in atmospheric Carbon Dioxide levels  , further intensification of Icehouse Earth conditions, roughly 1.
ages of rock strata, palaeo- environments and evolution of life. The fossil record has been used to develop the worldwide geological time-scale. Organisms may.
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