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MIOCENE

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Originally appearing in Volume V18, Page 565 of the 1911 Encyclopedia Britannica.
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MIOCENE , in See also:

geology, the See also:system of strata which occurs between the Oligocene and the See also:Pliocene. The See also:term, derived from the See also:Greek isiov, less, and Kaaos, See also:recent, was introduced by See also:Sir See also:Charles See also:Lyell, as indicating palaeonto(ogically a less percentage of recent See also:species than is found in the Pliocene. Variable lacustrine, estuarine and marine deposits, especially characterized by soft calcareous sandstones and conglomerates (" molasse ") and sandy See also:shell-beds (" faluns "), make up the Miocene system of the Neogene or newer See also:Tertiary in See also:Europe and western See also:Asia, where it attains its fullest development. A. de See also:Lapparent's See also:classification is here adopted: V. Pontian or Pannonian.—Brackish- and fresh-See also:water marls, limestones and gravels: occurring at See also:Vienna, in the See also:Caspian and eastern Mediterranean basins, and in See also:southern See also:France; mammalian deposits of Pikermi and the Siwalik Hills, with Hipparion gracile, See also:Mastodon longirostris, See also:Rhinoceros schleiermachi, numerous ruminants, Congeria subglobosa. Marine beds of See also:Belgium (See also:Black See also:Crag) and See also:north See also:Germany. IV. Sarmatian.—More or less See also:salt-water sands and marls of the same basins with Mastodon angustidens, Anchitherium aurelianense, Cerithium pictum, C. rubiginosum, Ostrea gingensis, Mactra podolica, Tapes gregarius. Stages IV. and V. represented in north-western France by marine sands (Cardita striatissima), and in See also:Algeria and See also:Morocco by marine marls and limestones. (b) Tortonian: Marine marls with Ancillaria glandiformis, Conus antiquus, Ranella marginate, Trochus patulus, Voluta rarispina. Laminated fresh-water limestones of Oeningen with See also:fish, countless See also:insects, and See also:plants showing seasonal changes of the See also:year in their successive layers (Ater trilobatum, Populus mutabilis, Juglans acuminata, Camphora, Podogonium); and the lacustrine deposits of central See also:Spain. (a) Helvetian: Marine shelly sandstones and conglomerates (" molasse " of See also:Switzerland) with Ostrea gingensis, Cardita jouanneti, Panopaea menardi, Conus ventricosus; the "faluns" of See also:Touraine and See also:Aquitaine; and the marine beds of Black See also:Sea See also:basin.

At the See also:

base of the marine Helvetian in the Vienna basin See also:clays (" Schlier ") with See also:rock-salt and See also:gypsum, and the lacustrine beds of See also:Gascony (Calcaire de Simorre with Mastodon tapiroides, M. simorrensis, See also:Dinotherium giganteum) occur. II. Burdigalian or Langhian.—Marine " faluns " of See also:Bordeaux (See also:Oliva basteroti, Turritella terebralis) ; marls of Langhe in See also:Liguria (Pecten burdigalensis) ; marine deposits of Vienna basin, Caspian region, See also:Tunis and Algeria; fresh-water sands and marls of See also:Orleans with Mastodon angustidens, M. tapiroides, Dinotherium cuvieri, See also:Anthracotherium onoideum; Littorinella clays of See also:Mainz basin with Acerotherium incisivum Littorinella acute, Dreyssenia brardi; fresh-water See also:grey " molasse " of Switzerland, with acacias, laurels, palms and sequoias. I. Aquitanian.—Limestones, sands and marls of lakes and lagoons, with Anthracotherium, Anchitherium, Acerotherium incisivum, Palaeochoerus typus, See also:Helix ramondi, Limnaea pachygaster, Planorbis See also:cornu, Potamides lamarcki; Quercus, See also:Acacia, Ficus, Camphora, Cinnamomum, Taxodium, Glyptostrobus, See also:Sequoia, Sabal, See also:Phoenix, occur in central France (Calcaire de la See also:Beauce) ; the plant-beds of Manosque; Mainz basin; See also:lower " molasse " of Switzerland with565. See also:lignite, gypsum, red marls and conglomerates; " See also:brown-See also:coal See also:series " of north Germany with lignite. Intercalated marine sandstones occur in Aquitaine and near See also:Marseilles; other marine developments occur in the " faluns " of Gascony (Lepidocyclina mantelli, Miogypsina burdigalensis), the upper Aquitanian of See also:Bavaria and See also:Austria-See also:Hungary (Ostrea crassiassima, Pectunculus pilosus), and in southern Spain, See also:Italy and See also:Malta (Lepidocyclina and Lithothamnium). Basic tuffs and lavas occur in See also:Auvergne. Some authors assign See also:Stage I. to the Oligocene, Stage V. to the Pliocene; Stages I. and II. correspond to the first, and III. to the second Mediterranean Stage of E. See also:Suess. In Europe a See also:general emergence of See also:land in See also:late Oligocene See also:time resulted at the beginniag of the Miocene (Aquitanian) in wide-spread lacustrine conditions throughout the western See also:part of that See also:continent, upon which the sea encroached at few points, though it had gained See also:access to the Vienna basin and extended westward into Bavaria. Otherwise, marine Aquitanian deposits are confined to the Mediterranean basin and the See also:south-See also:west corner of France.

Most of See also:

northern Europe, including the See also:British Isles, remained dry land throughout Miocene time. During the Burdigalian See also:period, with increasing See also:elevation of the See also:mountain regions and depression of the Mediterranean and Caspian basins, a marine invasion began, which passed its maximum in the Vindobonian. The Mediterranean reached eastward to See also:Persia, and, still open to the See also:Atlantic, sub-merged north See also:Africa, most of Italy and the neighbouring islands. It ascended the See also:Rhone valley, penetrated to the Mainz basin, and skirting the north flank of the Alpine region passed into the Vienna basin and thence around the Carpathian See also:tract into the Pontic and Caspian depression. The See also:waters of the Atlantic further invaded the regions of the See also:Garonne and the See also:Loire, isolated See also:Brittany and encroached upon north Europe between Belgium and See also:Denmark. The elevation of the See also:Alps, and probably of the whole Alpine system of mountain folds from Morocco to Indo-See also:China, though initiated by earlier Miocene and late Oligocene movements, took See also:place mainly during the latter part of the Vindobonian period, and was completed in the Sarmatian. The waters of the ocean were then excluded from the Caspian and eastern Mediterranean basins, and replaced by vast fresh-water lakes; while brackish-water lagoons occupied much of the western Mediterranean. This See also:great See also:retreat of the sea culminated in the Pontian stage, and land-connexion was established between North and South See also:America. Outside the See also:Eurasian region, Aquitanian deposits occur in See also:Formosa, See also:Java, See also:Borneo and See also:Madagascar; while Burdigalian deposits are found in Momgolia. The Vindobonian ranges from See also:Greenland, See also:Iceland and Spitzbergen, where it contains lignite and plants denoting a temperate See also:climate, by See also:Japan, Java and See also:India, to See also:Victoria. It recurs in the See also:Azores and the See also:Antilles, and at intervals along the See also:American continent from See also:Patagonia to See also:Alaska, where all three lower stages are represented, as also in the West Indies. Along the Atlantic slope of the See also:United States and around the Gulf of See also:Mexico the See also:complete Miocene series is See also:present, the Sarmatian and Pontian also occur in See also:California.

The Miocene was a period of See also:

change, of mountain-See also:building, See also:climatic differentiation hitherto unprecedented, and of moderation in organic See also:life, especially on land. The See also:rich See also:European See also:flora indicates an equable and moist sub-tropical climate, slowly cooling, as witnessed by the See also:gradual increase of trees with See also:deciduous foliage amongst those characteristic of more tropical conditions. Oaks, maples, poplars, planes, willows, Cinnamomum, Camphora, Myrica, Sequoia, Taxodium, Glyptostrobus and palms, flourished together. The marine calcareous alga Lithothamnium became an important See also:reef-building organism. Nummulites gave place to Lepidocyclina; lamellibranchs and particularly gasteropods abounded in the shallow seas, of which the See also:shark Carcharodon and the marine mammals Squalodon and Halitherium were amongst the largest denizens. The mammalian land-See also:fauna of Europe made striking advances, and assumed a decidedly See also:African aspect. Marsupials had disappeared from it before the Burdigalian period, during which See also:primitive genera like Palaeochoerus, Hyopotamus, and the hornless ruminants Anthracotherium and Brachyopus, became See also:extinct, while proboscideans (Mastodon, Dinotherium), rhinoceros and apes (Oreopithecus, Pliopithecus) came in, followed by antelopes, beavers and probably See also:Machaerodus in the Vindobonian. The spread of See also:turf-forming See also:grasses was succeeded in the Pontian by an enormous increase of herbivorous mammals, including Hipparion and horned ruminants (Helladotherium, Antilope, Cervus, Camelopardalis, Palaeotragus), whose migrations were facilitated by the See also:desiccation of the Mediterranean basin. (C. B.

End of Article: MIOCENE

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