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The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks).
The categorisation of the past into discrete, quantified named blocks of time is called periodization. [1] This is a list of such named time periods as defined in various fields of study. These can be divided broadly into prehistorical periods and historical periods (when written records began to be kept).
Geologic Time Spiral Historical geology or palaeogeology is a discipline that uses the principles and methods of geology to reconstruct the geological history of Earth . [ 1 ] Historical geology examines the vastness of geologic time, measured in billions of years, and investigates changes in the Earth , gradual and sudden, over this deep time .
This species might be evolved some time before, up to c. 2 Ma ago. c. 1.7 Ma – Australopithecines go extinct. c. 1.8–0.8 Ma – colonisation of Eurasia by Homo erectus. c. 1.5 Ma – earliest possible evidence of the controlled use of fire by Homo erectus; c. 1.2 Ma – Homo antecessor evolves. Paranthropus dies out.
The ice age was probably not as long-lasting as once thought; study of oxygen isotopes in fossil brachiopods shows that it was probably no longer than 0.5 to 1.5 million years. [41] The event was preceded by a fall in atmospheric carbon dioxide (from 7000ppm to 4400ppm) which selectively affected the shallow seas where most organisms lived.
The Geologic Calendar is a scale in which the geological timespan of the Earth is mapped onto a calendrical year; that is to say, the day one of the Earth took place on a geologic January 1 at precisely midnight, and today's date and time is December 31 at midnight. [1]
Eras in the Phanerozoic Eon [1] [2] Geologic Era: Span of Years: Notes: Cenozoic: present – 065.5 (+/- 0.3) Mya: many GSSP points Mesozoic: 065.5 (+/- 0.3) Mya – 251.0 (+/- 0.4) Mya: many GSSP points Paleozoic: 251.0 (+/- 0.4) Mya – 542.0 (+/- 1.0) Mya: mostly GSSP points Eras in the Proterozoic Eon 542.0 (+/- 1.0) Mya – 2500 Mya [1] [2 ...
Early Earth also known as proto-earth is loosely defined as encompassing Earth in its first one billion years, or gigayear (Ga, 10 9 y), [1] from its initial formation in the young Solar System at about 4.55 Ga to some time in the Archean eon in approximately 3.5 Ga. [2] On the geologic time scale, this comprises all of the Hadean eon, starting ...