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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 first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in the third timeline, the most recent period is expanded in the fourth timeline, and the most ...
Geologic Time – Period prior to humans. 4.6 billion to 3 million years ago. (See "prehistoric periods" for more detail into this.) Primatomorphid Era – Period prior to the existence of Primatomorpha; Simian Era – Period prior to the existence of Simiiformes; Hominoid Era – Period prior to the existence of Hominoidea
Geologic time is the timescale used to calculate dates in the planet's geologic history from its origin (currently estimated to have been some 4,600 million years ago) to the present day. Radiometric dating measures the steady decay of radioactive elements in an object to determine its age. It is used to calculate dates for the older part of ...
Geologic time shown in a diagram called a geological clock, showing the relative lengths of the eons of Earth's history and noting major events The geological history of Earth follows the major geological events in Earth's past based on the geologic time scale , a system of chronological measurement based on the study of the planet's rock ...
The science of geochronology is the prime tool used in the discipline of chronostratigraphy, which attempts to derive absolute age dates for all fossil assemblages and determine the geologic history of the Earth and extraterrestrial bodies.
Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time.. The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of the Earth.
The term geon (for geological eon) refers to large, geologic units of time. Geologists traditionally subdivide Earth history into a hierarchy of named intervals: eons, eras, periods, etc. (e.g., the Jurassic Period of the Mesozoic Era). Historians subdivide the history of human activity into intervals that are comparatively much shorter.