PERMIAN, a geological term designating the uppermost system of rocks of the Palaeozoic era and suggested by Sir R. Murchison in 1841, from their great development in the Russian Province of Perm.
Towards the close of the Carboniferous period a great dia strophic revolution of the earth's surface resulted in the upheaval of many parts of the crust and rearrangements of large areas of land and sea. In certain regions the movements were simple, either up or down ; whilst in others they gave rise to mountain building accompanied and followed by denudation. Thus in some cases Permian rocks are conformable to the Carboniferous whilst in others they are separated from them or still older rocks by an unconformity. In western Europe, for example, mountain ranges known as Armorican (Armorica, Brittany) ; in central Europe the Variscian Alps; in North America the Appalachians, and in Russia the Urals, were elevated at this time.
On the other hand in parts of eastern and southern Europe, central Asia, Australia and America the Carboniferous seas were persistent and there is a continuous suite of marine sediments bridging the interval between the Carboniferous and Permian of western Europe. Such intervening or transition beds whether of marine or continental type, are termed "Permo-Carboniferous." Confusion has arisen, and still persists to some extent, by the inclusion in the Permian of deposits which are really Carboniferous or Triassic in age, especially in areas where the continental type of deposit was prevalent. Such areas were characterized by their aridity and resembled the Aralo-Caspian region, the Arizona desert and similar tracts of the present-day, i.e., inland drainage basins embracing in places inland seas, salt-lakes and lagoons. The sandy plains or depressions were bordered by mountains gashed by canons, usually dry but occasionally flushed by torrential rains.
In Europe the Permian consists of (I) the twofold, or "Dyas" type of Germany and (2) the Russian type. The Dyas occurs in great thickness flanking the Harz mountains and in the Rhine provinces, Thuringia, Saxony, Bavaria and Bohemia (Czecho slovakia). Two major divisions are recognized, of which the upper overlaps the lower and covers a greater area. They are as fol lows:— Zechstein (Marine series) : Upper.—Anhydrite, gypsum, rock
salt, dolomite, marl, foetid shale and limestone; Middle.—Dolo mite (Stinkschiefer and Great Dolomite) and gypsum; Lower.— Zechstein Limestone, Kupferschiefer and conglomerate.
Rothliegende (Terrestrial Series) : Upper.—Red sandstones and shales with melaphyre and conglomerate; Lower.—Sandstones and conglomerates on black shales, poor coals and clay-ironstones, and sheets of melaphyre (lava). Red and grey sandstones with impure limestones at base.
The clay-ironstones of the Rothliegende (Lower Lebach beds of the Saar region) have yielded a rich fauna (Archegosaurus, etc.) and flora (TV alchia, Callipteris).
Overlying the Zechstein conglomerate is the Kupferschiefer, a thin black marly shale containing bitumen, copper ore, plant and fish remains. Copper ore amounts to no more than 3%, but has given rise to this chief copper mines in Germany (Mansfeld, etc.) Of animals' remains in the Zechstein the limestone, 3o-33 f t. thick, contains the greater number, although they show signs of poverty; fewer occur in the Great Dolomite.
In Thuringia a Bryozoa reef in the Lower and Middle Zech stein extended for miles along the western and southern margin of the Zechstein sea, and in addition to Bryozoa contains a rich fauna which bears witness to the gradual desiccation of the sea and the dying out of individual species.
Beds of salt occur in the Upper Zechstein north of the Harz and are worked, amongst other places, at Stassfurt, where rock salt, 1,200 ft. thick, is followed by 15o ft. of potash and magnesia salts.
Eastwards the Zechstein extends into the Baltic provinces and the eastern Alps.
In south-eastern Russia the same types are recognized but there is an alternation of terrestrial and marine beds throughout the whole system. They cover an enormous tract, chiefly in the prov ince of Perm (and extend into Nova Zemlyi and Spitsbergen). Following the Carboniferous conformably they consist of sand stones, marls, shales, conglomerates and limestones—the latter containing a fauna similar to that of the Zechstein. Intercalated with these are beds of rock-salt, gypsum and coal. At the base are terrestrial beds with plants chiefly of Permian affinities.