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PERMIAN
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PERMIAN , in See also:geology, the youngest and uppermost See also:system of strata of the Palaeozoic See also:series, situated above the Carboniferous and below the Trias. The See also:term " Permian " (derived from the A(... A d. 1.,y...1u uy t.rwlui..0 ~L Mw •~• e. L'•. see.. See also:Russian See also:province of See also:Perm, where the rocks are extensively See also:developed) was introduced in 1841 by See also:Sir R. I. See also:Murchison. In See also:England the series of red sandstones, conglomerates, breccias and marls which overlie the See also:Coal See also:Measures were at one See also:time grouped together in one See also:great formation as the " New Red See also:Sandstone," in contradistinction to the Old Red Sandstone below the Carboniferous: they were likewise known as the Poikilitic series (from Gr. aoix0sos, mottled) from their mottled or variegated See also:colour. They are now divided into two systems or See also:groups of formations; the See also:lower portion being included in the Palaeozoic series under the name Permian, the upper portion being relegated to the Mesozoic series and termed Trias. In See also:Germany the name Dyas was proposed by J. See also:Marcou for the rocks of this See also:age on See also:account of the twofold nature of the series in Thuringia, See also:Saxony, &c. The intimate stratigraphical relation-See also:ship that exists in many quarters between the Permian rocks and the Carboniferous beds, and the See also:practical difficulties in the way of See also:drawing a satisfactory See also:base-See also:line to the system, have led to the See also:adoption of the term Permo-carboniferous in See also:South See also:Africa, See also:southern See also:Asia, See also:America, See also:Australia and See also:Russia, for strata upon this See also:horizon: C. W. von See also:Gumbel used " See also:Post-See also:carbon " in this sense. In a similar manner Permo-triassic has been employed in cases where a stratigraphical passage from rocks with Permian fossils to others bearing a Triassic See also:fauna is apparent. The Permian system in England consists of the following subdivisions:- W. of England. E. of England. 600 ft. 50-100 ft. See also:zone disappears, and we have a great See also:accumulation of red, arenaceous and gravelly rocks. The lower subdivision attains its greatest development in the vale of the See also:Eden, where it consists of See also:brick-red sandstones, the See also:Penrith sandstone series, with some beds of calcareous See also:conglomerate or See also:breccia, locally known as " brockram," derived from the See also:waste of the Carboniferous See also:Limestone. These red rocks extend across the Solway into the valleys of the Nith and See also:Annan, in the south of See also:Scotland, where they See also:lie unconformably on the Lower See also:Silurian rocks. Their breccias consist of fragments of the adjacent Silurian greywackes and shales, but near See also:Dumfries some calcareous breccias or " brockrams " occur. These brecciated masses have evidently accumulated in small lakes or narrow fiords. Much farther south, in See also:Staffordshire, and in the districts of the Clent and Abberley Hills, the brecciated conglomerates in the Permian series attain a thickness of 400 ft. They have been shown by Sir A. C. See also:Ramsay to consist in large measure of volcanic rocks, grits, slates and See also:lime-stones, which can be identified with rocks on the See also:borders of See also:Wales. Some of the stones are 3 ft. in See also:diameter and show distinct striation. The same writer pointed out that these Permian See also:drift-beds cannot be distinguished by any essential See also:character from See also:modern glacial drifts; on the other See also:hand, W. W. See also: It is a very variable See also:rock in its lithological characters, being sometimes dull, earthy, See also:fine-grained and fossiliferous, in other places quite crystalline, and composed of globular, reniform, botryoidal, or other irregular concretions of crystalline and frequently internally radiated dolomite. Though the Magnesian Limestone runs as a thick persistent zone down the east of England, it is represented on the See also:Lancashire and See also:Cheshire See also:side by See also:bright red and variegated sandstone covered by a thin See also:group of red marls, with numerous thin courses of limestone, containing Schizodus, Bakevellia and other characteristic fossils of the Magnesian Limestone. Concerning the rocks classed as Permian in the central counties of England there exists some doubt, for See also:recent See also:work tends to show that the lower parts are clearly related to the Carboniferous rocks by their fossils; while there is little See also:evidence to See also:warrant the exclusion of the higher beds from the Trias. Similarly in south See also:Devon, where red sandstones and coarse breccias are well exposed, it has been found difficult to say whether the series should be regarded as Triassic or Permian, though the prevailing tendency is to retain them in the latter system. The " Dyas " type of the system is found in enormous masses of strata flanking the Harz Mountains, and also in the See also:Rhine provinces, Saxony, Thuringia, See also:Bavaria and Bohemia. In See also:general terms it may be said that in this region there is a lower sandy and conglomeratic subdivision with an upper one more calcareous; the former is known as the Rothliegende, the latter as the Zechstein group. On the south side of the Harz Mountains the following subdivisions are recognized: Permian See also:Period Hypothetical See also:distribution of See also:Land &See also:Sea Land See also:aria: Sea and Lagoons/ areas See also:duel, sown 3 Upper Red sandstones, See also:clays, and See also:gypsum 2. Middle .. Magnesian limestone . Marl slate r Red and variegated sandstone Reddish-brown and See also:purple sandstones and marls, with calcareous conglomerates and breccias of volcanic rocks J From the thicknesses here given it is evident that the Permian rocks have a very different development on the two sides of England. On the east side, from the See also:coast of See also:Northumberland southwards to the plains of the See also:Trent, they consist chiefly of a great central mass of limestone. But on the See also:west side of the Pennine See also:Chain, and extending southwards into the central counties, the calcareous 1. Lower .. 10-30 " 600 " 3000 " 100-250 " See also:Anhydrite, gypsum, rock-See also:salt, dolomite, marl, fetid shale and limestone. The amorphous gypsum is the chief member of this group; the limestone is some-times full of See also:bitumen. Dolomite (See also:Haupt-dolomit), crystalline granular Middle (Rauchwacke), and fine powdery (Asche) with gypsum at bottom. r Zechstein-limestone, an argillaceous, thin-bedded compact limestone 15 to 90 ft. thick. Lower Kupfer-schiefer, a See also:black bituminous See also:copper-bearing shale, not more than 2 ft. thick, often much less, but very See also:constant. Zechstein-conglomerate and calcareous sandstone. Red sandstones (See also:Kreuznach beds), red shales Upper (Monsig beds) with sheets of melaphyre See also:tuff, and See also:quartz-See also:porphyry-conglomerate (Wadern, Oberhof, - Sotern and Tambach beds). Sandstones and glomerates (Tholayer beds) on black shales with poor coal seams and See also:clay See also:iron-stones (Lebach and Goldlauter beds). Lower Sandstones and shales with seams of coal on red and See also:grey sandstones and shales with impure limestones (Cusel beds, including Manebach beds, upper, and Gehren beds, lower). The name Rothliegende or Rothtodtliegende (red-dead-layer) was given by the miners because their ores disappeared in the red rocks below the copper-bearing Kupfer-schiefer. The Kupferschiefer, although so thin, has been worked in the See also:Mansfeld See also:district for a See also:long period; it contains abundant remains of See also:fish (Palaeoniscus, Platysomus) and See also:plants (Ullmannia). The beds of rock-salt in the See also:German Zechstein are of the greatest importance; at Sperenberg near See also:Berlin it has been penetrated to a See also:depth of 4000 ft. Associated with the salt, gypsum and anhydrite are numerous Upper See also:potassium and See also:magnesium salts, including carnallite, kieserite and polyhalite, which are exploited at See also:Stassfurt and are the only important potassium deposits known. Permian rocks of the Rothliegende type are scattered over a wide See also:area in See also:France, where the lower beds are usually conformable with the Coal Measures. In the upper beds occur the bituminous or " Boghead " shale of See also:Autun. In Russia strata of this age See also:cover an enormous area, in the Ural region, in the governments of Perm, Kasan, See also:Kostroma, and in See also:Armenia. The Russian Permian shows no See also:sharp See also:division into two series; the two types of See also:deposit tend to be more mixed and include in addition some deposits of the more open sea. The general sequence begins with the Artinsk beds, sandy and manly or conglomeratic beds in See also:close connexion with the Carboniferous, overlain by the See also:Kungur limestones and See also:dolomites; these are followed by red fresh-See also:water sandstcnes, over which comes an important series of copper-bearing sandstones and conglomerates. Above this, in Kostroma, See also:Vyatka and Kasan there is a calcareous and dolomitic series, the so-called " Russian Zechstein " with marine fossils; the uppermost beds are red marls, with few fresh-water fossils, the Tartarian beds. The character of the fossils in the Permian of the Mediterranean and south-east See also:Europe—well exemplified in the deposits of See also:Sicily—together with their more generally calcareous nature, indicate a more open sea and more See also:stable marine conditions than obtained farther See also:north. This sea is traceable across south-east Russia into the middle of Asia, through See also:Turkestan and See also:Persia, into the Salt Range of See also:India, where the Productus limestone may be taken as representative of the normal marine See also:plan of Permian times. Southwards, however, of the See also:Nerbudda See also:River another and quite distinct See also:continental assemblage of deposits holds the ground, viz. the lower portion of the great fresh-water See also:Gondwana system. The coarse Talchir conglomerates at the base are succeeded by the sandstones and shales of the Karharbari group, with numerous coal seams, and these in turn are followed by the Damuda series (upwards of io,000 ft.) of similar rocks, with ironstones and very valuable coal seams. All these strata are characterized by the presence of the Glossopteris See also:flora. A similar See also:succession of beds has been recorded in north-west See also:Afghanistan. In close relationship with the lower members of the See also:Indian Gondwana series, both as regards fossil contents and lithological characters, are the lower Karoo beds of South Africa (Dwyka conglomerate, Ecca shales and mudstones, See also:Beaufort beds and See also:Kimberley shales), also the coal-bearing beds of the See also:Transvaal; the Permo-carboniferous rocks of Australia (including the See also:rich coal measures of See also:Newcastle, the Greta coal measures and marine beds, upper and lower, of New South Wales; those of See also:Tasmania, the See also:Bowen River beds of See also:Queensland, and the Bacchus See also:Marsh glacial beds of See also:Victoria), and similar rocks in New See also:Zealand (Maitai formation, south See also:island ; Dun.Mountainlimestone and Rimutaka beds of the north island) and South America. In North America Permian rocks occur in the east in See also:Pennsylvania, West See also:Virginia, See also:Maryland and See also:Ohio (" Upper Barren Measures "), and in See also:Prince See also:Edward Island, New See also:Brunswick, where they succeed the Carboniferous rocks very regularly. West of the See also:Mississippi, in See also:Texas (7000 ft., including the See also:Wichita beds, Clear See also:Fork and See also:Double See also:Mountain beds), See also:Kansas and See also:Nebraska, the Permian is more extensive and on the whole is more readily separable from the Carboniferous. Here the lower beds are marine and contain many limestones and dolomites; the higher beds are mainly red See also:sand-stones and marls with gypsum; in Texas it is of See also:interest to See also:note the occurrence of copper-stained strata. These upper " Red Beds " are-often not clearly distinguishable from the Trias. See also:Life of the Permian Period.—The records of the plants and animals of this period are comparatively meagre. The plants show that a See also:gradual See also:change from the Carboniferous types was in progress. Two floral regions are clearly indicated, a See also:northern and a southern. In the latter, which may be regarded as conterminous with the See also:continent of Gondwana, the Lepidodendrons, Sigillarias, Calamites, &c., of the Coal Measures gave See also:place to a distinct flora, named from the prevalence of Glossopteris, the Glossopteris (See also:tongue-See also:fern) flora. Traces of this southern flora have been found in northern Russia. Gangamopteris, Callipteris, Taeniopteris, Schizopteris, Walchia, Voltzia, Ullmannia, Saportea, Baiera are characteristic Permian genera. Among the larger animals amphibians occupied a prominent position, their footprints being very See also:common in the sandstones; they include numerous Labyrinthodonts, Archegosaurus, Stereorachis, Branchiosaurus. At this time the true See also:reptiles began to leave their remains in the rocks; many highly interesting forms are known—Palaeohatteria, Proterosaurus, Stereosternum; others having certain mammalian characteristics include Pareiosaurus, Cynognathus, Dicynodon. Among the fishes may be mentioned Platysomus, Palaeoniscus, Amblypterus, Pleuracanthus. Turning to the invertebrates, undoubtedly the most interesting feature is gradual introduction into the See also:Cephalopoda of the ammonite-like forms such as Medlicottia, Waagenoceras, Popanoceras, in place of the more See also:simple lobed goniatites of the Carboniferous. Brachiopods (Productus horridus, Bakevellia tumida), Bryozoa and See also:corals were by no means scarce in the more open Permian seas. Schizodus Schlotheimii, Strophalosia Goldfussi, Myophoria, Leimyalind, See also:Bellerophon are characteristic Permian molluscs. The last of the See also:trilobites appears in the Permian of North America. The evidence so far obtained indicates that in Permian times much of the land in the northern hemisphere was near the general sea-level, and that conditions of considerable aridity prevailed which involved the repeated See also:isolation and evaporation of marine lagoons and land-locked seas. South of this region in Europe and Asia there extended an open " Mediterranean " sea, the " Tethys " of E. See also:Suess; while over an enormous area in the southern hemisphere a great' land area was spread, " Gondwana land," the land of the Glossopteris flora. At many points in this vast See also:tract, as we have seen, coarse conglomeratic. deposits, Talchir, Dwyka, Bacchus Marsh, &c., indicate profound glacial conditions, which some have thought were See also:present also in See also:Britain, Germany and elsewhere in the north. Moderate See also:earth movements were taking place in North America, where the Appalachian and Ouachita mountains were in course of See also:elevation, and in Europe this was a time of great volcanic activity. In the Saal region volcanic rocks in the lower Rothliegende have been penetrated for 1100 ft. without reaching the bottom, and elsewhere in central Europe great sheets of contemporaneous quartz porphyry, See also:granite porphyry, melaphyre and porphyrite are abundant with their corresponding tuffs. Melaphyres and tuffs appear in the See also:Vosges, which in the south of France are enormous masses of melaphyre and quartz porphyry. Basic lavas and tuffs—See also:diabase, pierite, See also:olivine See also:basalt and See also:andesite tuffs—were erupted from many small vents in See also:Ayrshire and the See also:Nish See also:basin, and basic lavas occur also in See also:Devonshire. Volcanic rocks occur also in New Zealand, See also:Sumatra and the Transvaal. Table of Permian Strata, showing approximate correlations. Britain. Saxony, Basin of the Stages. Thuringia, See also:Alps. Russia. India. North America. Bohemia. See also:Saar. Marls and Salt beds of Upper red Bellerophon Tartarian ^ a °' a ° ^ limestone. Marls. Thuringian gypsum. Stassfurt. 'a-, See also:san d tones, Dolomites Cephalopod m 0 cr.) a o Ma nesian Zechstein lime- and shales beds of u 4-J Z g limestone. stones. u breccias and of Neumarkt. Armenia. ~ Kansas. Ho., v conglomerates. Marl slate. Kupfer-schiefer. N Sandstones Copper- or,, y E Kiger a of GrOden. bearing a a Q See also:stage. a:5 ? Ca m ? c Red sandstones sandstones ro y U Salt F in Ural Fork a> v stage. o.0 E 3 a a Weissliegendes. with eruptive region. c°° Q a See also:Pun abian u~ c ` Tambach beds. rocks. Limestones s. ua u v-o w beds b° The of or g o Tim' > Oberhof beds v Kreuznach, a and dolo- is ti v c b o W mites of Saxonian eu~ ° o G Goldlauter o 0 o a -o " beds. o Wadern, v d Kostroma A, ^ c ro - o o o~ Sotern, (Russian F4 0 t~, ' 'Z ` = u" Tholey. E Zechstein). cif v ~ v~ L c .x o Kungur and c cr) E v See also:wellington o " D o c Manebach S Artinsk av a Q - a eds. °; A rti nski an o c - '- a beds. sr, Lebach beds. o sandstones. ti o o bM l ( a Brandschiefer Cusel beds. c . t, cn, c ro ofdstones,o-r} (marine) °.c T ~•" bedsn ro or s,-o a beds of Wessig. v c ~` Novaya ^ .. See also:Chase Autunian c o o Gehren beds. Zemblyayand x p., a a] I g' (continental) N. 4•~~ See also:Braunau beds ( Spitzbergen. a o a Q U of Bohemia. Additional information and CommentsThere are no comments yet for this article.
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