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Geological time - Coggle Diagram
Geological time
Radiometric dating
Planet Earth is a active planet, non of original rock remain on the surface for researches to determine accurate age of the planet, radiometric decay applied to dating of rock samples was used to understand the time scale of Earths geology.
The Earth is full of naturally accruing radioactive elements, scientists used decay of elements to determine age of fossils or rocks, technique relies on property if half life (time it takes for half the atoms of a radioactive isotope to decay into a brand new daughter isotope) , by measuring ratio of original radioactive element to the daughter isotope scientists can determine how many half lives the element has undergone
Dating rocks
Lava extruded from interior of Earth =igneous rock (extremely hot molten rock that when cooled does not contain traces of organic matter
Fossils found in sedimentary rocks, dated by using radioactive carbon, but because carbon decays relatively quickly, it only works for rocks younger than about 50 thousand years old. To date older rocks scientists look for igneous rock or volcanic ash in region of fossil fuels=bracketing age of sedimentary layers in which fossils occur. Oldest rock 4.3 billion years old found in Hudson bay North America, rocks from moon 4.4 billion years old
Fossils found in sedimentary rocks, dated by using radioactive carbon, but because carbon decays relatively quickly, it only works for rocks younger than about 50
Geologic time scale
Geological time scale subdivides all time into named units of abstract time in descending order these are called eons, eras, periods, epochs, ages
4 eons are
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First 3 eons are called the Precambrian times, other material and most of fossil fuels found on Earth are from most recent eon called Phanerozoic
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Periods and epochs initially determined by fossil disappearance but have further been refine by radiometric dating.
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