Accuracy of radiometric dating
The Triassic was named in 1834 by Friedrich von Alberti, after the three distinct rock layers (tri meaning "three") that are found throughout Germany and northwestern Europe—red beds, capped by marine limestone, followed by a series of terrestrial mud- and sandstones—called the "Trias".The Triassic is usually separated into Early, Middle, and Late Triassic Epochs, and the corresponding rocks are referred to as Lower, Middle, or Upper Triassic.Thus Triassic stratigraphy is mostly based on organisms that lived in lagoons and hypersaline environments, such as Estheria crustaceans.At the beginning of the Mesozoic Era, Africa was joined with Earth's other continents in Pangaea.Sediments and fossils suggestive of a more humid climate are known from the Anisian to Ladinian of the Tethysian domain, and from the Carnian and Rhaetian of a larger area that includes also the Boreal domain (e.g., Svalbard Islands), the North American continent, the South China block and Argentina.
In North America, for example, marine deposits are limited to a few exposures in the west.However, the climate shifted and became more humid as Pangaea began to drift apart.The end of the period was marked by yet another major mass extinction, the Triassic–Jurassic extinction event, that wiped out many groups and allowed dinosaurs to assume dominance in the Jurassic.The spermatophytes, or seed plants, came to dominate the terrestrial flora: in the northern hemisphere, conifers, ferns and bennettitales flourished.Glossopteris (a seed fern) was the dominant southern hemisphere tree during the Early Triassic period. The shelled cephalopods called ammonites recovered, diversifying from a single line that survived the Permian extinction.
Search for accuracy of radiometric dating:
The first nonmarine sediments in the rift that marks the initial break-up of Pangaea, which separated New Jersey from Morocco, are of Late Triassic age; in the U.