Carboniferous The Carboniferous system of rocks takes pride of place as the first stratigraphical system to be established formally. Early in the nineteenth century, long before W. D. Conybeare and W. Phillips coined the term ‘Carboniferous’ (1822), the Coal Measures, the Millstone Grit, the Mountain Limestone and the Old Red Sandstone had been recognized and shown as important formations on the several pioneer geological maps of Britain. The word Carboniferous seemed appropriate for rocks that occurred commonly together and several of which contained bands of coal (Latin carbo, coal). Later, the Old Red Sandstone was dropped from the quartet, but the others were perceived as related by their fossil content. Today the Carboniferous period is held to have begun around 355 Ma and to have lasted for 165 million years. It was a time of great advances in the history of life and one in which geographical change was immense. Perhaps we should not be surprised that so much changed: 165 million years is no small stretch of time, even of geological time.

Interest in this system of rocks has always been intense on account of the great reserves of hydrocarbons it contains. These fossil fuels lay at the core of the exploitation of natural resources that arose with the industrial revolution. Coal was a prodigious source of energy and materials for the production of iron and steel and for much of the nineteenth-century chemical industry. In the second half of the twentieth century, oil and gas from Carboniferous sources have largely replaced coal. Fossil fuels are formed, impounded, and located very largely on the basis of regional stratigraphy and where this is extensive, as in north-western Europe and eastern North American, great natural wealth results. It is no wonder, then, that the Carboniferous system has been the subject of a great deal of attention as well as academic interest.

The Carboniferous is unusual in that it is today divided into two Subsystems (Upper and Lower) and five series. A previous division of the system into a lower part, the Dinantian, and an upper, the Silesian, was based upon the succession in western Europe. These two divisions have not been retained in the global stratigraphic column, where the Upper and Lower Subsystems are not exactly their equivalents. Alternatives, though not exact equivalents, to the upper three series exist in the former USSR. Twenty-five stages have been named in western Europe; rather more have been erected in what is now Russia. Regional differences are also embodied in the American divisions of the system. Despite the general international usage of the European subdivisions, the American are almost exclusively used in North American literature.

Mississippian was the term first applied in 1870 by Alexander Winchell (1824–1891) to the limestone lying beneath the coal-bearing strata in the Mississippi valley. In 1891 Henry Shaler Williams (1847–1918) established the correlation of these strata with the Lower Carboniferous of Europe. For the overlying coal-bearing series he proposed the name Pennsylvanian, after the State in which they had become best known. Because there is a widespread unconformity between these two formations, they were for some time given the status of geological systems. It was not until 1953 that the United States Geological Survey adopted these terms, and it has since been shown that the Pennsylvanian boundary is younger than the Lower-Upper Carboniferous boundary in Europe. The International Commission on Stratigraphy accepts that the Carboniferous System is inconveniently large and proposes dividing it into two subsystems. The exact stratigraphical level at which a boundary is to be drawn between the two is not yet decided, but it might be close to the traditional level of the Mississippian-Pennsylvanian break.

Correlation within the Carboniferous has been developed to a relatively high level of precision on the basis of biozones using conodonts, brachiopods, corals, foraminifera, cephalopods, and brachiopods in the marine facies and macroplants and palynomorphs (spores and pollen) and non-marine bivalves in the continental facies. There are many horizons that can be dated on the basis of isotopic analysis. The base of the system has now been defined in the pelagic (open water) marine facies at the excellent section at La Serre in southern France. The base of the bed in which the conodont Siphonodella sulcata first appears (bed 89) and which is within the lineage from Siphonodella praesulcata to Siphonodella sulcata is the point at which the boundary is drawn. The pelagic facies is of world-wide distribution, and auxiliary stratotypes have been selected at Nanbiancun in South China and Hasselbachtal in Germany. This level is as near to the base of the classic cephalopod zone of Gattendorfia as can be found.

Maps of the Carboniferous world show us the gradual drawing together of three great continental masses and associated smaller islands, continuing the process which had got under way during the preceding Devonian period (Fig. 1). Laurussia is the name given to the continental grouping of North America, Greenland, and southern and western Europe. Associated with these ancient stable cratons were new sedimentary basins at their margins (and also adjacent to the old Caldonian orogenic belt). Across the middle of Laurussia ran the Equator, while its northern margin lay just beyond 40°N. Not far off to the north-east lay the craton of Siberia, known as Angaraland, almost half as big as Laurussia. To the south of these continents was Gondwanaland, an agglomeration of today's southern continents and India. It stretched from close to Central America to its north-eastern Australian extremity in the southern tropics and into the south polar latitudes. Plate-tectonic movements now combined to suture Laurussia and western Gondwanaland together. Orogenic activity was concentrated along the southern margin of Laurussia where the small land masses were driving against the continental foundation and deforming the sedimentary basins as they progressed. Seas closed, uplands emerged, volcanic activity took place, and the entire continental margin grew by the addition of these new terrains.

On the western margin of Laurussia and the Andean sector of Gondwanaland, similar crustal activity was adding new strips of upland to the continent. Elsewhere around Gondwanaland comparable accretionary processes were enlarging the continental margins. Granitic batholiths were slowly emplaced in many of these areas. By the end of the Carboniferous period the effect of all this plate-tectonic activity was twofold: to draw all the continental fragments into the supercontinent Pangaea, and to increase the volume of the ocean basins.

Almost everywhere the upper part of the Carboniferous system shows cyclic sedimentation, and finally a pronounced regression of the sea accompanied by the spread of continental sedimentation. In a great swathe of country from the western USA to eastern Canada, the British Isles, and across Europe into the Donetz basin there were repeated sudden episodes of rising sea level followed by longer phases of deltaic and continental deposition. The culmination of each cycle was the establishment of a tropical forest, on the floor of which accumulated the plant debris that was to become almost a quarter of the world's total coal resources. In the southern parts of the USA, coal-bearing cycles of sedimentation gave rise to widespread but geographically variable units, known as cyclothems.

Long-continued, and sometimes fierce, argument has concerned the underlying cause of this repetitive process. Repeated transgression by the sea was followed by sand and clay build-up and the establishment of a widespread and dense vegetation cover. Such vigorous forest growth required a hot, humid climate. This seems to have been experienced throughout much of the tropics and to the north in North China, Kazkhstania, and Siberia (parts of Angaraland). Thus climate, local tectonics, and the global rise and fall of sea level have all been considered as prime causes of cyclothems. All three must have had an influence, but the view today is that sea-level changes in response to continental ice growth and decay in southern Gondwanaland was the prime mover.

Carboniferous plants in Europe show little trace of strong seasonal growth. This implies that they grew under constantly warm rather than seasonal conditions. In Angaraland the plants do have well-developed seasonal rings, showing that the winter months were cold. Coals occurring in Gondwanaland also show the effect of a seasonal climate, cool rather than warm. Elsewhere in the tropics, both north and south of the equator, evaporites were being precipitated in shallow arms and coastal reaches of the sea. Carboniferous evaporites occur today in the western USA, the Arctic, adjacent to the Ural mountains, and in central Asia, as well as in parts of Brazil and North Africa. Here, aridity was the norm, and the landscapes around the salt basins were probably clothed only in very sparse vegetation, if any.

The ultimate in cooler global conditions was attained in the far south. Glaciation is recorded by widespread boulder clays or tillites in Gondwanaland south of latitude 60°, which persisted from the Early Carboniferous into the Early Permian. The ice sheets grew to enormous sizes in South America, South Africa, India, and Antarctica, in places almost reaching the middle latitudes. They had a history of repeated growth and decline, and their effect upon sea level was to keep it constantly moving up or down as the ice volume changed. From time to time, and as the continents moved, the centre of ice accumulation shifted, but the maximum spread of the ice seems to have been late in the Carboniferous.

Life in the seas and oceans was prolific in Carboniferous time, especially in the shallow waters of the tropics. Bottom-dwelling faunas were dominated by brachiopods, corals, and echinoderms. The productid brachiopods included some of the largest forms ever to exist, while many other kinds persisting from the Devonian were also very successful. The crinoids were locally sufficiently abundant to produce limestone deposits extending over thousands of square kilometres. Rugose and tabulate corals gave rise to reef structures in many regions, usually with the help of stromatoporoids and calcareous algae, which were also reef-builders in their own right. Many reefs were of great size and exercised some control over local sedimentation. Bryozoa, bivalves, and gastropods, together with a small number of trilobites, added to benthonic populations. The fusulinids were among the foremost of the foraminifera and were sufficiently abundant in late Carboniferous time to produce extensive sheets of foraminiferal limestone in North America. Among the plankton and nekton, the cephalopods were conspicuous predators. The goniatite ammonoids evolved rapidly and are of great biostratigraphic importance; the nautiloids, however, were in decline. Fish included many elasmobranchs as well as osteichthyes such as palaeoniscoids, dipnoi, selachians, and crossopterygians, together with the ancient acanthodians. Many of these groups produced animals of a relatively large size, but the giant placoderm fish that had been present in late Devonian seas were now extinct.

On land the vascular plants produced diverse and luxuriant floras with lycophytes, sphenophytes, ferns, seed ferns Cordaites, and, eventually, the first of the conifers. They were present virtually throughout the full range of climatic zones. Three botanical provinces have been recognized: in Laurussia, China, and Gondwanaland. The tropical Laurussian coastal coal forests were dominated by the lepidodendrales and the sphenophytes. Elsewhere a more xerophytic vegetation was present across the land. The forests afforded habitats for many aquatic invertebrates, fish, and amphibia. Terrestrial invertebrates were mostly arthropods, but land and fresh-water gastropods also existed. The insects rapidly evolved many very large flying species; many of them were clearly carnivores, but their mode of life remains uncertain. The base of the ecologial pyramid, however, was occupied by the multifarious plants, and it was highly productive.

The vertebrates, too, were commonly very large, adapting to new habitats by the evolution of new forms. Early Carboniferous tetrapods are known only from the coastal land of Laurussia from Iowa to Germany. Most are amphibians, but the earliest reptiles are recorded in Visean rocks. Late Carboniferous tetrapods have been discovered over a wider area, and a great increase in reptile diversity occurs. Not being tied by the necessity of a watery habitat for reproduction, the reptiles were able to enter the drier environments and to become much more active and mobile. The terrestrial habitats were undergoing wide geographical expansion at this time in both tropical and temperate latitudes.

Towards the end of the Carboniferous period the growing proximity of the continents to one another brought about marked changes in climate and crustal deformation of the now impacting continents. The coal forest regimes came to an end with the uplift of the land surface and with growing aridity. As the early students of the Palaeozoic rocks in Britain had perceived, the Carboniferous system is sandwiched between two systems with very prominent and extensive continental facies, the Devonian Old Red Sandstone and the Permian New Red Sandstone, and it constitutes in time a cycle of geological events and processes.

D. L. Dineley

Bibliography

Dias, C. M., Granados, L. F., Wager, R. F., and Winkler-Prins, C. F. (eds) (1983, 1985) The Carboniferous of the world, Vols I and II. IUGS Publications 16 and 20. Instituto Geológico y Minero de Espan`a and Empresa Nacional Adaro de Investigaciones Mineras, S. A., Madrid.
Ramsbottom, W. H. C. (1978) Carboniferous. In McKerrow, W. S. (ed.) The ecology of fossils, pp. 146–83. Duckworth, London.

Carboniferous

The Carboniferous period dates from 360 million to 280 million years ago. It gets its name from the vast deposits of coal produced when fluctuating seas drowned the tropical forests that covered much of North America and Europe.

The later Paleozoic (286 million to 570 million years ago) was a world that would be recognizable to us. By this time the teeming marine and land plants had expelled enough oxygen to produce an atmosphere very similar to our own. Vast forests greened the supercontinent Pangaea and supported a thriving animal population. We would be struck by the sheer size and variety of the flora and fauna: horsetails and scale trees that stood from 50 to 100 feet tall and dragonflies with 2-foot wingspans. Drippingly humid and silent, the monotonously green rain forest abounded with scuttling creatures familiar and unfamiliar. Animals that swam, crawled, and flew populated the tropical swamps of the forest. Snails and cockroaches and myriapods made a living on the rich forest floor, along with 6-foot centipedes and crocodile-like amphibians.

By this time all the major characters of evolution had come into being. There would still be millennia of ingenious refinements of size and shape and function, variations on the main themes to exploit the new Devonian (408 million to 438 million years ago) environment of land and air. The Phylum Chordata, comprised of animals with backbones, had previously experimented with fishes and amphibians; now, in the Carboniferous period, the chordates would diverge into reptiles.

In a remarkable adaptation referred to as the amniote radiation, amphibians had evolved from needing large bodies of water in order to reproduce. The method was a semipermeable, shelled or leathery skinned egg filled with enough nutrients to sustain an embryo until it was fully developed. This dry-land form of reproduction necessitated yet another biological innovation, namely internal fertilization. These two features enabled the former amphibians to radiate out into every niche of the giant land mass, in turn encouraging further evolutionary branching. As the tetrapods (fourlimbed animals) spread through the luxuriant vegetation, they made adjustments in their dentition and digestive tracts to take advantage of the untapped food source on land.

Three distinct groups of reptiles emerged, differentiated by the number of small holes in the skull located behind the eyes at either side. Anapsids had no holes and included the turtles and their now-extinct relatives. Synapsids, with a single pair of temporal openings, included all of the mammal-like reptiles, now extinct, and their distant relatives, the true mammals. Diapsids were reptiles with two pairs of openings. Petrocalosaurus was a rapid, 16-inch insectivore whose genes gave rise to lizards, snakes, crocodiles, dinosaurs, and birds.

By the Carboniferous period, the constant ebb and flow of continental drift had once again pushed the land masses back together into one supercontinent, Pangaea, whose northern forests were periodically flooded by shallow tropical seas. The cycle of vegetation and flooding produced organic beds of peats that were compressed into coal layers over 3,000-feet thick. Exquisitely preserved fossils appear in this coal, especially near the Czech mining town of Nyrany. Here, hundreds of specimens have been collected, representing twenty amphibian and four reptile species as well as unusual fishes and small, shrimplike creatures.

In the Carboniferous seas, huge limestone reefs were being laid down by limy coral, brachiopod, and crinoid skeletons. These reefs were home to starfish, gastropods , and sea urchins, while giant coiled nautiloids and bony fish swam overhead.

see also Geological Time Scale.

Nancy Weaver

Bibliography

Asimov, Isaac. Life and Time. Garden City, NY: Doubleday and Company, 1978.

Fortey, Richard. Fossils: The Key to the Past. Cambridge, MA: Harvard University Press, 1991.

———. Life: A Natural History of the First Four Billion Years of Life on Earth. New York: Viking Press, 1998.

Friday, Adrian, and David S. Ingram, eds. The Cambridge Encyclopedia of Life Sciences. London: Cambridge University Press, 1985.

Gould, Stephen Jay, ed. The Book of Life. New York: W. W. Norton and Company, 1993.

Lambert, David. The Field Guide to Prehistoric Life. New York: Facts on File, 1985.

McLoughlan, John C. Synapsida: A New Look into the Origin of Mammals. New York: Viking Press, 1980.

Steele, Rodney, and Anthony Harvey, eds. The Encyclopedia of Prehistoric Life. New York: McGraw Hill, 1979.

Wade, Nicholas, ed. The Science Times Book of Fossils and Evolution. New York: The Lyons Press, 1998.

CARBONIFEROUS OR MISSISSIPPIAN AND PENNSYLVANIAN?

In the United States, the Carboniferous Period is usually broken down into two periods— Mississippian and Pennsylvanian. Sedimentary rocks that formed in shallow oceans characterize the Mississippian or "Lower Carboniferous." These rocks are usually found along the Mississippi River. Coal bearing sedimentary rocks that formed in swamps and river deltas characterize the Pennsylvanian or "Upper Carboniferous. These rocks are usually found in the northeastern United States.

Carboniferous The penultimate period of the Palaeozoic Era, preceded by the Devonian and followed by the Permian. It began about 362.5 Ma ago and ended about 290 Ma ago. In Europe the lower part of the system is known as the Dinantian. It is divided into two stages and is characterized by marine limestones with a rich coral-brachiopod fauna. In contrast the upper part, the Silesian, which is subdivided into three stages, is noted for the deposition of terrestrial and freshwater sediments. North American geologists subdivide the Carboniferous System into two periods or subperiods. Of these the lower (362.5–322.8 Ma ago) is called the Mississippian and is the equivalent of the Dinantian stages (the Tournaisian and Visean) plus the lower part of the Silesian. The upper period, the Pennsylvanian (322.8–290 Ma ago), is the equivalent of most of the Silesian. During the Carboniferous very lush, swamp forests dominated the landscape in low-lying areas, where minor changes in sea level alternately exposed land supporting forest then inundated and buried the vegetation. The climate was very humid until the end of the period, when it became arid, conditions then selecting against seed-bearing plants. The forests were dominated by Lycopsida and Calamitaceae, some of which grew to the size of trees (e.g. Lepidophloios species grew up to 50 m tall) and the forest floor supported ferns and seed ferns. The first tetrapods (e.g. the amphibian Ichthyostega) appeared very early in the Carboniferous. The buried vegetation was compressed and changed through time to form the rich coal measures of southern Wales, England, Scotland, the USA, and many other areas worldwide, in which recognizable seed plants are common fossils.

Carboniferous The penultimate period of the Palaeozoic Era, from about 360–286 Ma ago, preceded by the Devonian and followed by the Permian. In Europe the lower part of the period is termed the Dinantian. It is divided into two stages and is characterized by marine limestones with a rich coral-brachiopod fauna. In contrast, the upper part, the Silesian, which is subdivided into three stages, is noted for the deposition of terrestrial and freshwater sediments. N. American geologists subdivide the Carboniferous into two periods or subperiods. Of these the lower is named the Mississippian and is the equivalent of the Dinantian stages (the Tournaisian and Visean). The upper period, the Pennsylvanian, is the equivalent of the Silesian. During the Carboniferous, very lush, swamp forests dominated the landscape in low-lying areas, where minor changes in sea-level alternately exposed land supporting forest then inundated and buried the vegetation. The forests were dominated by Lycopsida and Calamitaceae, some of which grew to the size of trees (see CALAMITES CISTIIFORMES and LEPIDODENDRON SELAGINOIDES), and the forest floor supported ferns and seed ferns. The buried vegetation was compressed and changed through time to form the rich coal measures of southern Wales, England, Scotland, the USA, and many other areas world-wide, in which recognizable seed plants are common fossils.

Carboniferous A geological period in the Palaeozoic era. It began about 360 million years ago, following the Devonian period, and extended until the beginning of the Permian period, about 285 million years ago. In Europe the period is divided into the Lower and Upper Carboniferous, which roughly correspond to the Mississippian and Pennsylvanian periods, respectively, of North America. During the Lower Carboniferous a marine transgression occurred and the characteristic rock of this division – the Carboniferous limestone – was laid down in the shallow seas. Fauna included foraminiferans, corals, ectoprocts, brachiopods, blastoids, and other invertebrates. The Upper Carboniferous saw the deposition of the millstone grit, a mixture of shale and sandstone formed in deltaic conditions, followed by the coal measures, alternating beds of coal, sandstone, shale, and clay. The coal was formed from the vast swamp forests composed of seed ferns, lycopsids, and other plants. During the period fishes continued to diversify and amphibians became more common.

Carboniferous Penultimate period of the Palaeozoic Era, preceded by the Devonian and followed by the Permian. It began about 362.5 Ma ago and ended about 290 Ma ago. In Europe the lower part of the system is termed the Dinantian. It is divided into two series and is characterized by marine limestones with a rich coral-brachiopod fauna. In contrast the upper part, the Silesian, which is subdivided into three series, is noted for the deposition of terrestrial and freshwater sediments. The vast forests of the Upper Carboniferous gave rise to the rich coal measures of south Wales, England, Scotland, and many other areas worldwide. N. American geologists subdivide the Carboniferous System into two subsystems. Of these the lower (362.5–322.8 Ma ago) is named the Mississippian and is the equivalent of the Dinantian sub-System plus the lower part of the Silesian sub-System. The upper sub-system, the Pennsylvanian (322.8–290 Ma ago), is the equivalent of most of the Silesian.

Carboniferous The penultimate period of the Palaeozoic Era, from about 359.2–299 Ma ago, preceded by the Devonian and followed by the Permian. In Europe the lower part of the period is termed the Dinantian. It is divided into three stages and is characterized by marine limestones with a rich coral-brachiopod fauna. In contrast the upper part, the Silesian, which is subdivided into four stages, is noted for the deposition of terrestrial and freshwater sediments. The vast forests of the Upper Carboniferous gave rise to the rich coal measures of S. Wales, England, Scotland, and many other areas Worldwide. N. American geologists subdivide the Carboniferous into two sub-periods. Of these the lower is named the Mississippian and is the equivalent of the Dinantian stages (the Tournaisian, Visean, and Serpukhovian). The upper period, the Pennsylvanian, is the equivalent of the Silesian.

Carboniferous Fifth geological division of the Palaeozoic era, lasting from 360 to 286 million years ago. It is often called the ‘Age of Coal’ because of its extensive swampy forests of conifers and tree ferns that turned into most of today's coal deposits. Amphibians flourished, marine life abounded in warm, inland seas, and the first reptiles appeared.

Car·bon·if·er·ous / ˌkärbəˈnifərəs/ • adj. Geol. of, relating to, or denoting the fifth period of the Paleozoic era, between the Devonian and Permian periods. ∎  (the Carboniferous) [as n.] the Carboniferous period or the system of rocks deposited during it.

carboniferous •Arras, embarrass, harass •gynandrous, polyandrous •Pancras • charas • Tatras • disastrous •ferrous • leprous • ambidextrous •Carreras, mayoress •scabrous •cirrus, Pyrrhus •chivalrous •citrous, citrus •ludicrous • tenebrous •Cyrus, Epirus, papyrus, virus •fibrous • hydrous • Cyprus •retrovirus • monstrous •brachiosaurus, brontosaurus, canorous, chorus, Epidaurus, Horus, megalosaurus, pelorus, porous, sorus, stegosaurus, Taurus, thesaurus, torus, tyrannosaurus •walrus •ochrous (US ocherous) •cumbrous • wondrous • lustrous •Algeciras, Severus •desirous •Arcturus, Epicurus, Honduras •barbarous • tuberous • slumberous •Cerberus • rapturous •lecherous, treacherous •torturous • vulturous • Pandarus •slanderous • ponderous •malodorous, odorous •thunderous • murderous •carboniferous, coniferous, cruciferous, melliferous, odoriferous, pestiferous, somniferous, splendiferous, umbelliferous, vociferous •phosphorous, phosphorus •sulphurous (US sulfurous) •Anaxagoras, Pythagoras •clangorous, languorous •rigorous, vigorous •dangerous • verdurous •cankerous, cantankerous, rancorous •decorous • Icarus • valorous •dolorous • idolatrous •amorous, clamorous, glamorous •timorous •humerus, humorous, numerous •murmurous • generous • sonorous •onerous • obstreperous • Hesperus •vaporous • viviparous • viperous •Bosporus, prosperous •stuporous • cancerous •Monoceros, rhinoceros •sorcerous • adventurous • Tartarus •nectarous • dexterous • traitorous •preposterous • slaughterous •boisterous, roisterous •uterus • adulterous • stertorous •cadaverous • feverous •carnivorous, herbivorous, insectivorous, omnivorous •Lazarus