THE ALPS The marine Trias is frequently referred to as "Alpine," "Medi terranean" or "Pelagic." In Europe and eastwards through Asia it forms part of the deposits of the great Mediterranean sea, or "Tethys," situated north of Gondwanaland. (See article PER MIAN.) The facies is distributed widely in southern Europe, particularly in the eastern Alps, Apennines, Sicily, Balearic Islands, Spain, Balkan Peninsula and part of the Carpathians.
In the Alps, where the rocks form a broad zone on both sides, sandy rocks are subordinate to limestones, dolomites and marls, whilst the fauna makes that of the German Muschelkalk appear poor by comparison. The following divisions are recognized, chiefly in the eastern Alps :— The Werfen beds (Salzburg) are conformable to the under lying Permian and consist of red sandy shales and beds of gypsum and rock-salt, with impure limestone in the upper part. The Alpine Muschelkalk is highly fossiliferous and differs in many respects from that of Germany, being of truly marine character. Typically the Ladinic consists of limestones, dolomites, tuffs and lavas, though there is also a calcareous and a dolomitic facies. In the St. Cassian beds the fossils are dwarfed.
The Raibl beds indicate a regression of the sea, evidenced by plant-bearing sandstones (Lunt), and marls with gypsum. The Rhaetic consists generally of marly limestones forming a thin but continuous sheet.
The small masses of limestone of Bogdoberg (Kirghiz Steppes, south Russia) overlying red sandstones and marls are portions of Muschelkalk of Alpine type on the equivalents of the Bunter.
Marine Trias occurs also in Asia Minor, many parts of Asia as far east as China, the Indo-Pacific islands, Japan, Spitsbergen, New Zealand, New Guinea, Timor, Peru, Colombia, Mexico and western North America. With the exception of the last these areas lie north of or on the margins of Gondwanaland. Certain of these occurrences are dealt with below.
In India the finest development of marine Trias occurs in the Himalayas. In Spiti (Lilang), Garhwal and Kumaon and on the north-west extension of the same geo-synclinal axis in Kashmir the rocks comprise three subdivisions corresponding to the Alpine Bunter, Muschelkalk and Keuper (with Rhaetic). The Bunter,
which rests conformably on the Permian Productus Shales, con sists of so ft. of shales and limestones with an ammonite fauna (Otoceras, Ophiceras, Afeekoceras). The Muschelkalk is chiefly concretionary limestones, 400 ft. thick, with Ceratites, Siberites, etc., and, at the top a Daonella (lamellibranch) limestone. The Keuper comprises 2,000 ft. of shale and marl beneath thick limestones and dolomites with a cephalopodan fauna. The lower division corresponds to the Karnic and Noric stages, whilst the limestones probably represent the Rhaetic.
In the north-west Himalayas (Sirban Mountains, Hazara) Trias rests unconformably on Devonian shales and limestones (Infra Trias). Felsitic lavas are succeeded by limestones from Soo 1,200 ft. thick, with characteristic fossils.
Trias of reduced thickness and comprising only the Lower and part of the Middle division occurs in the western part of the Salt Range where it caps the Permian Productus Limestone. The Lower division consists of thin limestones with an extraordinary abundance of Ceratites. The Middle, or .Muschelkalk, contains many cephalopods.
In north Baluchistan shales and slates with a few limestones represent the Rhaetic stage. It contains Al onot is and cephalopods (Didymites, Halosites) and rests unconformably on Carboniferous Fusulina limestone. A similar development occurs in the Arakan \roma of Burma whilst in the Northern Shan States the Noping beds, with A vicuia contorta, suggest a Rhaetic age.
Peninsular India was at this time joined up to Australia and Antarctica, Madagascar, South Africa, and South America, and formed part of the continent named Gondwanaland. (See article PERMIAN.) The Trias is represented by the Middle Gondwana Series which is divided into three groups:—Panchet, Kamthi and Maleri (or Denwa) corresponding approximately to the divisions of the German Trias. In the type area (Satpura Range) the rocks consist of massive sandstones, conglomerates, grits and shales devoid of coal seams and are unconformable to the Permian Damuda Series. Vegetation, hitherto profuse, became scanty or failed.