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Triassic

marine, trias, red, period and various

TRIASSIC, the oldest period of the Meso zoic era and the system of rocks then formed, so named from its threefold division in Ger many, as follows: Transition or Rhmtic, Upper Trias or Keuper, Middle Trias or Muschelkalk, Lower Trias or Bunter Sandstein. Of these divisions, the middle one alone is marine, and characterized by marine fossils. The Keuper consists of non-marine sandstones, marls and clays, often with coal seams. The Bunter con sists of mottled red and green sandstones, marls and conglomerates with occasional beds of dolomite, rock salt and gypsum. The typical marine Triassic series of beds is found in Alps, Himalayas and Siberia. The Triassic is preceded by Carboniferous and followed by Jurassic. In various portions of California and other western States sections are obtained which cover each a greater or smaller interval of the entire Triassic column. Altogether the entire interval• is pretty well covered by the various local sections, so that western North America furnishes a nearly complete series of marine Triassic strata. In other regions of North America the Triassic strata are chiefly non marine. Such is the condition in the interior and such is the character of the Newark sys tem of eastern North America (Nova Scotia, Connecticut Valley, New York, New Jersey and Pennsylvania to Virginia region and the isolated patches in Virginia and the Carolinas). In Europe the Triassic is often called the "New Red" sandstone, in distinction from the "Old Red" sandstone of the Devonian system. This name is little used in the United States.

In portions of the United States the rocks of this period are hardly separable from those of the Jurassic, so that they are frequently known to American paleontologists as "Jura trias." They are represented by various forma

tions along the northern Atlantic Coast ; and in this age were erupted the trap overflows whose remains are the Palisades of the Hudson, East and West Rocks, at New Haven, and other sim ilar outcrops in Connecticut. In the interior the terrestrial red beds in the foot-hills of the Rocky Mountains are in part Permian, in part Triassic; and there are extensive marine Jura trias formations on the Pacific Coast, which was the only part of the United States to be ex tensively submerged during the period. Triassic strata are known over large areas in various parts of the Old World; and in all countries yield some of the best building stones and grits. The famous "Brownstones" of New Eng land and New Jersey are of this age.

The life of the period is not greatly different from that of the Carboniferous, especially in the vegetation, as cycads, tree-ferns, etc., re mained prominent. (See PALEOBOTA NY) . Fishes abounded. Reptiles multiplied on land, particularly the bipedal carnivorous Dinosaurs (terrible reptiles), which reached 40 feet in length, and were the animals that made the so called "bird-tracks" of the Connecticut Valley. Marine forms also began to develop, such as mosasaurs, plesiosaurs and their relatives in all parts of the world. The most important and characteristic creatures of the time, however, were amphibians, especially of the Stegocephal ian type. Compare JURASSIC. See GEOLOGY, and the authorities there cited. Also NEWARK SERIES; NEW RED SANDSTONE.