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A megaannus (Ma) represents one million (10 6) years. 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 ...
Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to 1,000,000 years (i.e. 1 × 10 6 years), or approximately 31.6 teraseconds. Usage [ edit ]
The Proterozoic eon lasted from 2.5 Ga to 538.8 Ma (million years) ago. [105] In this time span, cratons grew into continents with modern sizes. The change to an oxygen-rich atmosphere was a crucial development. Life developed from prokaryotes into eukaryotes and multicellular forms.
The Eocene (IPA: / ˈ iː ə s iː n, ˈ iː oʊ-/ EE-ə-seen, EE-oh-[5] [6]) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era.
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata. [2] In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age. [3]
The Ca-Al-rich inclusions, which formed 2 million years before the chondrules, [1] are a key signature of a supernova explosion. c. 4,567 ±3 Ma – Rapid collapse of hydrogen molecular cloud , forming a third-generation Population I star , the Sun , in a region of the Galactic Habitable Zone (GHZ), about 25,000 light years from the center of ...
The Carboniferous (/ ˌ k ɑːr b ə ˈ n ɪ f ər ə s / KAR-bə-NIF-ər-əs) [6] is a geologic period and system of the Paleozoic era that spans 60 million years from the end of the Devonian Period 358.86 Ma (million years ago) to the beginning of the Permian Period, 298.9 Ma.
The most recent and best-known, the Cretaceous–Paleogene extinction event, which occurred approximately 66 Ma (million years ago), was a large-scale mass extinction of animal and plant species in a geologically short period of time. [72]