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Regulatory BodyEarth Geological Time Scale
The geological time scale (GTS) divides and chronicles earth’s evolutionary history into various periods from the beginning to the present based on definite events that marked a major change in earth’s physical, chemical and biological features. Major changes in earth’s physical and biological history stretch over several millions of years and hence in GTS all the divisions are expressed in ‘million years (mya – million years ago).’ The primarily defined divisions of time are eons, the Hadean, the Archean, the Proterozoic and the Phanerozoic. The first three of these can be referred to collectively as the Precambrian supereon. Each eon is subsequently divided into eras, which in turn are divided into periods, which are further divided into epochs.
1. Eons
Eons are the largest intervals of geologic time and are hundreds of millions of years in duration
Time Period
4.6– 4.0 BYA
Earth’s Condition
Earth formed about 4.6 billion years ago during the birth of our solar system. For several hundred million years after the formation of the solar system the Earth was continuously bombarded by meteoric debris + planetesimals thus the surface of the Earth probably re-surfaced number of Times. Atmosphere : Bombardment and Stripping of Hydrogen and Helium The early atmosphere, with hydrogen and helium, is supposed to have been stripped off because of the solar winds. Volcanic outgassing created primordial atmosphere of CO2
Earth formed about 4.6 billion years ago during the birth of our solar system. For several hundred million years after the formation of the solar system the Earth was continuously bombarded by meteoric debris + planetesimals thus the surface of the Earth probably re-surfaced number of Times. Atmosphere : Bombardment and Stripping of Hydrogen and Helium The early atmosphere, with hydrogen and helium, is supposed to have been stripped off because of the solar winds. Volcanic outgassing created primordial atmosphere of CO2
Formation of the Moon
It is estimated that a body of the size of one to three times that of mars named Theia (approximately 4.5 billion years ago) collided into the earth sometime shortly after the earth was formed 4.5 Billion years ago. It blasted a large part of the earth into space which formed the Moon As the earth cooled, the water vapour released started getting condensed. Liquid water oceans existed despite the surface temperature of 230° C because due to the increased atmospheric pressure of the CO2 atmosphere. Formation of Moon crash knocked Earth sideways, changing its angle of tilt to the sun from 0 degrees to 23.5 degrees. As a result, the Earth started to have seasons: winter for the hemisphere tilted away from the sun, and summer for the hemisphere tilted towards the sun
Time Period
4 – 2.5 billion
Earth’s Condition
The Earth Tilt cooled the Earth. Also Degassing cooled the atmosphere, dissolving in ocean water removed most CO2 from the atmosphere. Water vapour were released from the interior solid earth along with methane and ammonia and condensed into rain. Nitrogen was probably also released by volcanoes which gradually built up because it is unreactive. During the Archean Eon, Earth was primarily a water world with large, shallow oceans covering most of the planet, dotted with small, volcanic islands. The loss of Internal heat also occurred via convection cells for interior of Earth . As the Earth Cooled the denser materials Collapsed under their own gravity sank to the centre, forming an iron-nickel rich core Lighter buoyant silicate-rich magma rose to the surface. Outer layers had solidified for oceans to form. The oldest rocks we have date to 4 billion years ago are Archean. Earth’s crust cooled enough to allow the formation of Protocontinents and oceans.
Biodiversity
Cyno bacteria conducted photosynthesis to produce Oxygen around 2.7 billion to 2.8 billion years ago. The earliest identifiable fossils consist of stromatolites, which are microbial mats formed in shallow water by cyanobacteria.
Time Period
2,500 -541 mya
Earth’s Condition
It was a very tectonically active period in the Earth’s history. It featured the first definitive supercontinent cycles supercontinent in Rodinia and modern orogeny (mountain building).Oxygen and Nitrogen increased in the Atmosphere . and had shaped up like the Present Earth Bacteria begin producing oxygen,
Biodiversity
Sudden rise of life forms soft-bodied multicellular (arthropods)
2. Phanerozoic Eon [ Eras and Period ]
Paleozoic Era Periods
Time Period
541 – 485.4 MYA
Earth’s Condition
As the Cambrian began, Rodina began to fragment into smaller continents Gondwana heading to South Pole
Biodiversity
Plants like algae evolved, and marine arthropods (shelled organisms) dominated fauna, First Fish (Vertebrate) Almost all marine phyla evolved in this period
Time Period
4 – 2.5 billion
Earth’s Condition
The Earth Tilt cooled the Earth. Also Degassing cooled the atmosphere, dissolving in ocean water removed most CO2 from the atmosphere. Water vapour were released from the interior solid earth along with methane and ammonia and condensed into rain. Nitrogen was probably also released by volcanoes which gradually built up because it is unreactive. During the Archean Eon, Earth was primarily a water world with large, shallow oceans covering most of the planet, dotted with small, volcanic islands. The loss of Internal heat also occurred via convection cells for interior of Earth . As the Earth Cooled the denser materials Collapsed under their own gravity sank to the centre, forming an iron-nickel rich core Lighter buoyant silicate-rich magma rose to the surface. Outer layers had solidified for oceans to form. The oldest rocks we have date to 4 billion years ago are Archean. Earth’s crust cooled enough to allow the formation of Protocontinents and oceans.
Biodiversity
Cyno bacteria conducted photosynthesis to produce Oxygen around 2.7 billion to 2.8 billion years ago. The earliest identifiable fossils consist of stromatolites, which are microbial mats formed in shallow water by cyanobacteria.
Time Period
2,500 -541 mya
Earth’s Condition
It was a very tectonically active period in the Earth’s history. It featured the first definitive supercontinent cycles supercontinent in Rodinia and modern orogeny (mountain building).Oxygen and Nitrogen increased in the Atmosphere . and had shaped up like the Present Earth Bacteria begin producing oxygen,
Biodiversity
Sudden rise of life forms soft-bodied multicellular (arthropods)
Time Period
2,500 -541 mya
Earth’s Condition
It was a very tectonically active period in the Earth’s history. It featured the first definitive supercontinent cycles supercontinent in Rodinia and modern orogeny (mountain building).Oxygen and Nitrogen increased in the Atmosphere . and had shaped up like the Present Earth Bacteria begin producing oxygen,
Biodiversity
Sudden rise of life forms soft-bodied multicellular (arthropods)
Time Period
2,500 -541 mya
Earth’s Condition
It was a very tectonically active period in the Earth’s history. It featured the first definitive supercontinent cycles supercontinent in Rodinia and modern orogeny (mountain building).Oxygen and Nitrogen increased in the Atmosphere . and had shaped up like the Present Earth Bacteria begin producing oxygen,
Biodiversity
Sudden rise of life forms soft-bodied multicellular (arthropods)
Time Period
2,500 -541 mya
Earth’s Condition
It was a very tectonically active period in the Earth’s history. It featured the first definitive supercontinent cycles supercontinent in Rodinia and modern orogeny (mountain building).Oxygen and Nitrogen increased in the Atmosphere . and had shaped up like the Present Earth Bacteria begin producing oxygen,
Biodiversity
Sudden rise of life forms soft-bodied multicellular (arthropods)
Mesozoic Era Periods
Time Period
541 – 485.4 MYA
Earth’s Condition
As the Cambrian began, Rodina began to fragment into smaller continents Gondwana heading to South Pole
Biodiversity
Plants like algae evolved, and marine arthropods (shelled organisms) dominated fauna, First Fish (Vertebrate) Almost all marine phyla evolved in this period
Time Period
4 – 2.5 billion
Earth’s Condition
The Earth Tilt cooled the Earth. Also Degassing cooled the atmosphere, dissolving in ocean water removed most CO2 from the atmosphere. Water vapour were released from the interior solid earth along with methane and ammonia and condensed into rain. Nitrogen was probably also released by volcanoes which gradually built up because it is unreactive. During the Archean Eon, Earth was primarily a water world with large, shallow oceans covering most of the planet, dotted with small, volcanic islands. The loss of Internal heat also occurred via convection cells for interior of Earth . As the Earth Cooled the denser materials Collapsed under their own gravity sank to the centre, forming an iron-nickel rich core Lighter buoyant silicate-rich magma rose to the surface. Outer layers had solidified for oceans to form. The oldest rocks we have date to 4 billion years ago are Archean. Earth’s crust cooled enough to allow the formation of Protocontinents and oceans.
Biodiversity
Cyno bacteria conducted photosynthesis to produce Oxygen around 2.7 billion to 2.8 billion years ago. The earliest identifiable fossils consist of stromatolites, which are microbial mats formed in shallow water by cyanobacteria.
Time Period
2,500 -541 mya
Earth’s Condition
It was a very tectonically active period in the Earth’s history. It featured the first definitive supercontinent cycles supercontinent in Rodinia and modern orogeny (mountain building).Oxygen and Nitrogen increased in the Atmosphere . and had shaped up like the Present Earth Bacteria begin producing oxygen,
Biodiversity
Sudden rise of life forms soft-bodied multicellular (arthropods)
Cenozoic Era Periods and Epocs
Time Period
541 – 485.4 MYA
Earth’s Condition
As the Cambrian began, Rodina began to fragment into smaller continents Gondwana heading to South Pole
Biodiversity
Plants like algae evolved, and marine arthropods (shelled organisms) dominated fauna, First Fish (Vertebrate) Almost all marine phyla evolved in this period
Time Period
4 – 2.5 billion
Earth’s Condition
The Earth Tilt cooled the Earth. Also Degassing cooled the atmosphere, dissolving in ocean water removed most CO2 from the atmosphere. Water vapour were released from the interior solid earth along with methane and ammonia and condensed into rain. Nitrogen was probably also released by volcanoes which gradually built up because it is unreactive. During the Archean Eon, Earth was primarily a water world with large, shallow oceans covering most of the planet, dotted with small, volcanic islands. The loss of Internal heat also occurred via convection cells for interior of Earth . As the Earth Cooled the denser materials Collapsed under their own gravity sank to the centre, forming an iron-nickel rich core Lighter buoyant silicate-rich magma rose to the surface. Outer layers had solidified for oceans to form. The oldest rocks we have date to 4 billion years ago are Archean. Earth’s crust cooled enough to allow the formation of Protocontinents and oceans.
Biodiversity
Cyno bacteria conducted photosynthesis to produce Oxygen around 2.7 billion to 2.8 billion years ago. The earliest identifiable fossils consist of stromatolites, which are microbial mats formed in shallow water by cyanobacteria.
Time Period
2,500 -541 mya
Earth’s Condition
It was a very tectonically active period in the Earth’s history. It featured the first definitive supercontinent cycles supercontinent in Rodinia and modern orogeny (mountain building).Oxygen and Nitrogen increased in the Atmosphere . and had shaped up like the Present Earth Bacteria begin producing oxygen,
Biodiversity
Sudden rise of life forms soft-bodied multicellular (arthropods)