The Cryptic era refers to the earliest period of the Earth. It began 4567.17 million years ago when the Earth formed and ended 4150 million years ago. This time is cryptic because very little geological evidence is left from this age. Any geological features -- if there were any -- were probably destroyed in the early bombardment phase that continued over the Hadean. ...more on Wikipedia about "Cryptic era"
In general usage, an eon (sometimes spelled aeon) is a very long period of time. Geologists refer to an eon as the largest period of geologic time. For example, the Phanerozoic Eon, which is about 550 million years long, covers the period of time during which animals with hard shells that fossilize well have been abundant. ...more on Wikipedia about "Eon (geology)"
A geologic era is a subdivision of geologic time that is a separate classification that divides the Phanerozoic Eon into three parts timeframes. The the Paleozoic, the Mesozoic, and the Cenozoic represent the major stages in the macroscopic fossil record. 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. There is evidence that catastrophic meteorite impacts played a role in demarcating the differences between the eras. ...more on Wikipedia about "Era (geology)"
Faunal stages are a subdivision of geologic time used primarily by paleontologists who study fossils rather than by geologists who study rock formations. Typically, a faunal stage will consist of a series of rocks that contain similar fossils. There will be one or more index fossils that are usually common, easily recognized, and limited to a single, or at most a few, stages. Thus, for example, a North American paleontologist finding fragments of the trilobite Olenellus would identify the beds as being from the Waucoban Stage whereas fragments of a later trilobite such as Elrathia would identify the stage as Albertan. ...more on Wikipedia about "Faunal stage"
The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. The table of geologic periods presented here is in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy, and uses the standard color codes of the United States Geologic Survey. ...more on Wikipedia about "Geologic time scale"
A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphic section which serves as the reference section for a particular boundary on the geologic time scale. The effort to define GSSPs is conducted by the International Commission on Stratigraphy, a part of the International Union of Geological Sciences. Most, but not all, GSSPs are based on paleontological changes. Hence GSSPs are usually described in terms of transitions between different faunal stages, though far more faunal stages have been described than GSSPs. The GSSP definition effort commenced in 1977. As of 2004, 45 of the 96 GSSPs required have been approved. ...more on Wikipedia about "Global Boundary Stratotype Section and Point"
A Global Standard Stratigraphic Age, often abbreviated GSSA, is a chronological age used to define the boundaries between different periods or epochs on the geologic time scale. ...more on Wikipedia about "Global Standard Stratigraphic Age"
The name Hadean refers to the geologic period before 3800 million years ago ( mya). The geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks. In the last decades of the 20th century geologists identified a few Hadean rocks from Western Greenland, Northwestern Canada and Western Australia. Some sources of information give other dates for the end of the Hadean period. ...more on Wikipedia about "Hadean"
In New Zealand, these epochs and stages use local place names (mainly Maori in origin) back to the Permian. Prior to this time, they largely use the same terms as used in the Australian geologic time scale, and are not divided into epochs. In practice, these early terms are rarely used, as most New Zealand geology is of more recent origin. In all cases, New Zealand uses the same periods as used internationally; it is only the subdivisions of these periods that have been renamed. Very few epochs and stages cross international period boundaries, almost all of them being during the Cenozoic Era. ...more on Wikipedia about "New Zealand geologic time scale"
A geologic period is a subdivision of geologic time that divides Eras into smaller timeframes. Periods are considered an informal designation but are still used to demarcate rock layers and the fossil record. While paleontologists often refer to faunal stages rather than geologic periods, they are often used in popular presentations of paleontology. Such references include the book and movie Jurassic Park. ...more on Wikipedia about "Period (geology)"
Permo-Carboniferous is strata deposited between the Carboniferous and Permian periods that are not differentiated because of the presence of transitional fossils, and also where no conspicuous stratigraphic break is present. ...more on Wikipedia about "Permo-Carboniferous"
The Precambrian is an informal name for the eons of the geologic timescale that came before the current Phanerozoic eon. It spans from the formation of Earth around 4500 Ma (million years ago) to the evolution of abundant macroscopic hard-shelled fossils, which marked the beginning of the Cambrian, the first period of the first era of the Phanerozoic eon, some 542 Ma. ...more on Wikipedia about "Precambrian"
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