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The Precambrian includes approximately 90% of geologic time. It extends from 4.6 billion years ago to the beginning of the Cambrian Period (about 539 Ma).It includes the first three of the four eons of Earth's prehistory (the Hadean, Archean and Proterozoic) and precedes the Phanerozoic eon.
The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [3] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...
The history of the Earth can be organized chronologically according to the geologic time scale, which is split into intervals based on stratigraphic analysis. [2] [21] The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space ...
Post-classical history – Period of time that immediately followed ancient history. Depending on the continent, the era generally falls between the years AD 200–600 and AD 1200–1500. Depending on the continent, the era generally falls between the years AD 200–600 and AD 1200–1500.
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 ...
The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and 246.7 Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era. It is ...
Geochronology is different in application from biostratigraphy, which is the science of assigning sedimentary rocks to a known geological period via describing, cataloging and comparing fossil floral and faunal assemblages.
In 1741 the best-known institution in the field of natural history, the National Museum of Natural History in France, created the first teaching position designated specifically for geology. [19] This was an important step in further promoting knowledge of geology as a science and in recognizing the value of widely disseminating such knowledge.