A geologic era is a subdivision of geologic time that divides an Eon into smaller buckets. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other The Phanerozoic Eon is divided into three such time frames: the Paleozoic, Mesozoic, and Cenozoic represent the major stages in the macroscopic fossil record. The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The Cenozoic (also Caenozoic or Cainozoic) Era (ˌsiːnəˈzoʊɪk/ /ˌsɛn- (meaning "new life" ( Greek ( kainos) "new" FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. These eras are separated by catastrophic extinction boundaries, the P-T boundary between the Paleozoic and the Mesozoic and the K-T boundary between the Mesozoic and the Cenozoic. In Biology and Ecology, extinction is the cessation of existence of a Species or group of taxa. The Permian–Triassic (P–Tr extinction event, informally known as the Great Dying, was an Extinction event that occurred, and 70 percent of terrestrial The K-T boundary is a geological signature usually a thin band dated to 65 There is evidence that catastrophic meteorite impacts played a role in demarcating the differences between the eras. See also Impact crater An impact event is the Collision of a large Meteoroid, Asteroid or Comet (generically
The Hadean, Archean and Proterozoic eons were as a whole formerly called the Precambrian. The Hadean (ˈheɪdiən is the geologic eon before the Archean. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current This covered the four billion years of Earth history prior to the appearance of hard-shelled animals. More recently, however, those eons have been subdivided into eras of their own.
| Era | Time frame (Ma = million years ago) |
|---|---|
| Cenozoic | 66 Ma to present day |
| Mesozoic | 252 Ma–66 Ma |
| Paleozoic | 542 Ma–252 Ma |
| Neoproterozoic | 1000 Ma–542 Ma |
| Mesoproterozoic | 1600 Ma–1000 Ma |
| Paleoproterozoic | 2500 Ma–1600 Ma |
| Neoarchean | 2800 Ma–2500 Ma |
| Mesoarchean | 3200 Ma–2800 Ma |
| Paleoarchean | 3600 Ma–3200 Ma |
| Eoarchean | 3800 Ma (unofficial)–3600 Ma |
| Hadean Eon not officially divided into eras |
Formation of Earth to 3800 Ma |
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