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Carboniferous

The Carboniferous is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period  Ma (million years ago) to the beginning of the Permian Period,  Ma. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian and the later Pennsylvanian.

The name Carboniferous means "coal-bearing", from the Latin ("coal") and  ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern "system" names, it was coined by geologists William Conybeare and William Phillips in 1822, based on a study of the British rock succession.

Carboniferous is the period during which both terrestrial animal and land plant life was well established. Stegocephalia (four-limbed vertebrates including true tetrapods), whose forerunners (tetrapodomorphs) had evolved from lobe-finned fish during the preceding Devonian period, became pentadactylous during the Carboniferous. The period is sometimes called the Age of Amphibians because of the diversification of early amphibians such as the temnospondyls, which became dominant land vertebrates, as well as the first appearance of amniotes including synapsids (the clade to which modern mammals belong) and sauropsids (which include modern reptiles and birds) during the late Carboniferous. Due to the raised atmospheric oxygen level, land arthropods such as arachnids (e.g. trigonotarbids and Pulmonoscorpius), myriapods (e.g. Arthropleura) and insects (e.g. Meganeura) also underwent a major evolutionary radiation during the late Carboniferous. Vast swaths of forests and swamps covered the land, which eventually became the coal beds characteristic of the Carboniferous stratigraphy evident today.

The later half of the period experienced glaciations, low sea level, and mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change.

Etymology and history
The development of a Carboniferous chronostratigraphic timescale began in the late 18th century. The term "Carboniferous" was first used as an adjective by Irish geologist Richard Kirwan in 1799 and later used in a heading entitled "Coal-measures or Carboniferous Strata" by John Farey Sr. in 1811. Four units were originally ascribed to the Carboniferous, in ascending order, the Old Red Sandstone, Carboniferous Limestone, Millstone Grit and the Coal Measures. These four units were placed into a formalised Carboniferous unit by William Conybeare and William Phillips in 1822 and then into the Carboniferous System by Phillips in 1835. The Old Red Sandstone was later considered Devonian in age.

The similarity in successions between the British Isles and Western Europe led to the development of a common European timescale with the Carboniferous System divided into the lower Dinantian, dominated by carbonate deposition and the upper Silesian with mainly siliciclastic deposition. The Dinantian was divided into the Tournaisian and Viséan stages. The Silesian was divided into the Namurian, Westphalian and Stephanian stages. The Tournaisian is the same length as the International Commission on Stratigraphy (ICS) stage, but the Viséan is longer, extending into the lower Serpukhovian.

North American geologists recognised a similar stratigraphy but divided it into two systems rather than one. These are the lower carbonate-rich sequence of the Mississippian System and the upper siliciclastic and coal-rich sequence of the Pennsylvanian. The United States Geological Survey officially recognised these two systems in 1953. In Russia, in the 1840s British and Russian geologists divided the Carboniferous into the Lower, Middle and Upper series based on Russian sequences. In the 1890s these became the Dinantian, Moscovian and Uralian stages. The Serpukivian was proposed as part of the Lower Carboniferous, and the Upper Carboniferous was divided into the Moscovian and Gzhelian. The Bashkirian was added in 1934.

In 1975, the ICS formally ratified the Carboniferous System, with the Mississippian and Pennsylvanian subsystems from the North American timescale, the Tournaisian and Visean stages from the Western European and the Serpukhovian, Bashkirian, Moscovian, Kasimovian and Gzhelian from the Russian. With the formal ratification of the Carboniferous System, the Dinantian, Silesian, Namurian, Westphalian and Stephanian became redundant terms, although the latter three are still in common use in Western Europe.

Stratigraphy
Stages can be defined globally or regionally. For global stratigraphic correlation, the ICS ratify global stages based on a Global Boundary Stratotype Section and Point (GSSP) from a single formation (a stratotype) identifying the lower boundary of the stage. Only the boundaries of the Carboniferous System and three of the stage bases are defined by global stratotype sections and points because of the complexity of the geology. The ICS subdivisions from youngest to oldest are as follows:

Mississippian
The Mississippian was proposed by Alexander Winchell in 1870 named after the extensive exposure of lower Carboniferous limestone in the upper Mississippi River valley. During the Mississippian, there was a marine connection between the Paleo-Tethys and Panthalassa through the Rheic Ocean resulting in the near worldwide distribution of marine faunas and so allowing widespread correlations using marine biostratigraphy. However, there are few Mississippian volcanic rocks, and so obtaining radiometric dates is difficult.

The Tournaisian is defined by the first appearance of the conodont Siphonodella sulcata within the evolutionary lineage from Siphonodella praesulcata to Siphonodella sulcata. This was ratified by the ICS in 1990. However, in 2006 further study revealed the presence of Siphonodella sulcata below the boundary, and the presence of Siphonodella praesulcata and Siphonodella sulcata together above a local unconformity. This means the evolution of one species to the other, the definition of the boundary, is not seen at the La Serre site making precise correlation difficult. The Viséan Stage was officially defined as the first black limestone in the Leffe facies at the Bastion Section in the Dinant Basin. These changes are now thought to be ecologically driven rather than caused by evolutionary change, and so this has not been used as the location for the GSSP. Instead, the GSSP for the base of the Visean is located in Bed 83 of the sequence of dark grey limestones and shales at the Pengchong section, Guangxi, southern China. It is defined by the first appearance of the fusulinid Eoparastaffella simplex in the evolutionary lineage Eoparastaffella ovalis – Eoparastaffella simplex and was ratified in 2009.

The Serpukhovian Stage currently lacks a defined GSSP. The Visean-Serpukhovian boundary coincides with a major period of glaciation. The resulting sea level fall and climatic changes led to the loss of connections between marine basins and endemism of marine fauna across the Russian margin. This means changes in biota are environmental rather than evolutionary making wider correlation difficult. Work is underway in the Urals and Nashui, Guizhou Province, southwestern China for a suitable site for the GSSP with the proposed definition for the base of the Serpukhovian as the first appearance of conodont Lochriea ziegleri.

Pennsylvanian
The Pennsylvanian was proposed by J.J.Stevenson in 1888, named after the widespread coal-rich strata found across the state of Pennsylvania. The closure of the Rheic Ocean and formation of Pangea during the Pennsylvanian, together with widespread glaciation across Gondwana led to major climate and sea level changes, which restricted marine fauna to particular geographic areas thereby reducing widespread biostratigraphic correlations. Extensive volcanic events associated with the assembling of Pangea means more radiometric dating is possible relative to the Mississippian.

The GSSP for the base of the Pennsylvanian Subsystem and Bashkirian Stage is located at Arrow Canyon in Nevada, US and was ratified in 1996. It is defined by the first appearance of the conodont Declinognathodus noduliferus. Arrow Canyon lay in a shallow, tropical seaway which stretched from Southern California to Alaska. The boundary is within a cyclothem sequence of transgressive limestones and fine sandstones, and regressive mudstones and brecciated limestones.

The Moscovian currently lacks a defined GSSP. The fusulinid Aljutovella aljutovica can be used to define the base of the Moscovian across the northern and eastern margins of Pangea, however, it is restricted in geographic area, which means it cannot be used for global correlations. The first appearance of the conodonts Declinognathodus donetzianus or Idiognathoides postsulcatus have been proposed as a boundary marking species and potential sites in the Urals and Nashui, Guizhou Province, southwestern China are being considered.

The Kasimovian covers a period of globally low sea level, which has resulted in disconformities within many sequences of this age. This has created difficulties in finding suitable marine fauna that can used to correlate boundaries worldwide. The Kasimovian currently lacks a defined GSSP; potential sites in the southern Urals, southwest USA and Nashui, Guizhou Province, southwestern China are being considered.

The Gzhelian currently lacks a defined GSSP. The first appearance of the fusulinid Rauserites rossicus and Rauserites stuckenbergi can be used in the Boreal Sea and Paleo-Tethyan regions but not eastern Pangea or Panthalassa margins. Potential sites in the Urals and Nashui, Guizhou Province, southwestern China for the GSSP are being considered.

The GSSP for the base of the Permian is located in the Aidaralash River valley near Aqtöbe, Kazakhstan and was ratified in 1996. The beginning of the stage is defined by the first appearance of the conodont Streptognathodus postfusus.

Cyclothems
A cyclothem is a succession of non-marine and marine sedimentary rocks, deposited during a single sedimentary cycle, with an erosional surface at its base. Whilst individual cyclothems are often only metres to a few tens of metres thick, cyclothem sequences can be many hundreds to thousands of metres thick and contain tens to hundreds of individual cyclothems. Cyclothems were deposited along continental shelves where the very gentle gradient of the shelves meant even small changes in sea level led to large advances or retreats of the sea. Cyclothem lithologies vary from mudrock and carbonate-dominated to coarse siliciclastic sediment-dominated sequences depending on the paleo-topography, climate and supply of sediments to the shelf. The main period of cyclothem deposition occurred during the Late Paleozoic Ice Age from the Late Mississippian to early Permian, when the waxing and waning of ice sheets led to rapid changes in eustatic sea level. The growth of ice sheets led global sea levels to fall as water was lock away in glaciers. Falling sea levels exposed large tracts of the continental shelves across which river systems eroded channels and valleys and vegetation broke down the surface to form soils. The non-marine sediments deposited on this erosional surface form the base of the cyclothem. As sea levels began to rise, the rivers flowed through increasingly water-logged landscapes of swamps and lakes. Peat mires developed in these wet and oxygen-poor conditions, leading to coal formation. With continuing sea level rise, coastlines migrated landward and deltas, lagoons and esturaries developed; their sediments deposited over the peat mires. As fully marine conditions were established, limestones succeeded these marginal marine deposits. The limestones were in turn overlain by deep water black shales as maximum sea levels were reached.

Ideally, this sequence would be reversed as sea levels began to fall again; however, sea level falls tend to be protracted, whilst sea level rises are rapid, ice sheets grow slowly but melt quickly. Therefore, the majority of a cyclothem sequence occurred during falling sea levels, when rates of erosion were high, meaning they were often periods of non-deposition. Erosion during sea level falls could also result in the full or partial removal of previous cyclothem sequences. Individual cyclothems are generally less than 10 m thick because the speed at which sea level rose gave only limited time for sediments to accumulate.

During the Pennsylvanian, cyclothems were deposited in shallow, epicontinental seas across the tropical regions of Laurussia (present day western and central US, Europe, Russia and central Asia) and the North and South China cratons. The rapid sea levels fluctuations they represent correlate with the glacial cycles of the Late Paleozoic Ice Age. The advance and retreat of ice sheets across Gondwana followed a 100 kyr Milankovitch cycle, and so each cyclothem represents a cycle of sea level fall and rise over a 100 kyr period.

Coal formation
Coal forms when organic matter builds up in waterlogged, anoxic swamps, known as peat mires, and is then buried, compressing the peat into coal. The majority of Earth's coal deposits were formed during the late Carboniferous and early Permian. The plants from which they formed contributed to changes in the Carboniferous Earth's atmosphere, and the coal fueled the Industrial Revolution.

During the Pennsylvanian, vast amounts of organic debris accumulated in the peat mires that formed across the low-lying, humid equatorial wetlands of the foreland basins of the Central Pangean Mountains in Laurussia, and around the margins of the North and South China cratons. During glacial periods, low sea levels exposed large areas of the continental shelves. Major river channels, up to several kilometres wide, stretched across these shelves feeding a network of smaller channels, lakes and peat mires. These wetlands were then buried by sediment as sea levels rose during interglacials. Continued crustal subsidence of the foreland basins and continental margins allowed this accumulation and burial of peat deposits to continue over millions of years resulting in the formation of thick and widespread coal formations. During the warm interglacials, smaller coal swamps with plants adapted to the temperate conditions formed on the Siberian craton and the western Australian region of Gondwana.

There is ongoing debate as to why this peak in the formation of Earth's coal deposits occurred during the Carboniferous. The first theory, known as the delayed fungal evolution hypothesis, is that a delay between the development of trees with the wood fibre lignin and the subsequent evolution of lignin-degrading fungi gave a period of time where vast amounts of lignin-based organic material could accumulate. Genetic analysis of basidiomycete fungi, which have enzymes capable of breaking down lignin, supports this theory by suggesting this fungi evolved in the Permian. However, significant Mesozoic and Cenozoic coal deposits formed after lignin-digesting fungi had become well established, and fungal degradation of lignin may have already evolved by the end of the Devonian, even if the specific enzymes used by basidiomycetes had not. The second theory is that the geographical setting and climate of the Carboniferous were unique in Earth's history: the co-occurrence of the position of the continents across the humid equatorial zone, high biological productivity, and the low-lying, water-logged and slowly subsiding sedimentary basins that allowed the thick accumulation of peat were sufficient to account for the peak in coal formation.

Palaeogeography
During the Carboniferous, there was an increased rate in tectonic plate movements as the supercontinent Pangea assembled. The continents themselves formed a near circle around the opening Paleo-Tethys Ocean, with the massive Panthalassic Ocean beyond. Gondwana covered the south polar region. To its northwest was Laurussia. These two continents slowly collided to form the core of Pangea. To the north of Laurussia lay Siberia and Amuria. To the east of Siberia, Kazakhstania, North China and South China formed the northern margin of the Paleo-Tethys, with Annamia laying to the south.

Variscan-Alleghanian-Ouachita orogeny
The Central Pangean Mountains were formed during the Variscan-Alleghanian-Ouachita orogeny. Today their remains stretch over 10,000 km from the Gulf of Mexico in the west to Turkey in the east. The orogeny was caused by a series of continental collisions between Laurussia, Gondwana and the Armorican Terrane Assemblage (much of modern day Central and Western Europe including Iberia) as the Rheic Ocean closed and Pangea formed. This mountain building process began in the Middle Devonian and continued into the early Permian.

The Armorican terranes rifted away from Gondwana during the Late Ordovician. As they drifted northwards the Rheic Ocean closed in front of them, and they began to collide with southeastern Laurussia in the Middle Devonian. The resulting Variscan orogeny involved a complex series of oblique collisions with associated metamorphism, igneous activity, and large-scale deformation between these terranes and Laurussia, which continued into the Carboniferous.

During the mid Carboniferous, the South American sector of Gondwana collided obliquely with Laurussia's southern margin resulting in the Ouachita orogeny. The major strike-slip faulting that occurred between Laurussia and Gondwana extended eastwards into the Appalachian Mountains where early deformation in the Alleghanian orogeny was predominantly strike-slip. As the West African sector of Gondwana collided with Laurussia during the Late Pennsylvanian, deformation along the Alleghanian orogen became northwesterly-directed compression.

Uralian orogeny
The Uralian orogeny is a north–south trending fold and thrust belt that forms the western edge of the Central Asian Orogenic Belt. The Uralian orogeny began in the Late Devonian and continued, with some hiatuses, into the Jurassic. From the Late Devonian to early Carboniferous, the Magnitogorsk island arc, which lay between Kazakhstania and Laurussia in the Ural Ocean, collided with the passive margin of northeastern Laurussia (Baltica craton). The suture zone between the former island arc complex and the continental margin formed the Main Uralian Fault, a major structure that runs for more than 2,000 km along the orogen. Accretion of the island arc was complete by the Tournaisian, but subduction of the Ural Ocean between Kazakhstania and Laurussia continued until the Bashkirian when the ocean finally closed and continental collision began. Significant strike-slip movement along this zone indicates the collision was oblique. Deformation continued into the Permian and during the late Carboniferous and Permian the region was extensively intruded by granites.

Laurussia
The Laurussian continent was formed by the collision between Laurentia, Baltica and Avalonia during the Devonian. At the beginning of the Carboniferous it lay at low latitude in the southern hemisphere and drifted north during the Carboniferous, crossing the equator during the mid-to-late Carboniferous and reaching low latitudes in the northern hemisphere by the end of the Carboniferous. The Central Pangean Mountain drew in moist air from the Paleo-Tethys Ocean resulting in heavy precipitation and a tropical wetland environment. Extensive coal deposits developed within the cyclothem sequences that dominated the Pennsylvanian sedimentary basins associated with the growing orogenic belt.

Subduction of the Panthalassic oceanic plate along its western margin resulted in the Antler orogeny in the Late Devonian to Early Mississippian. Further north along the margin, slab roll-back, beginning in the Early Mississippian, led to the rifting of the Yukon-Tanana terrane and the opening of the Slide Mountain Ocean. Along the northern margin of Laurussia, orogenic collapse of the Late Devonian to Early Mississippian Innuitian orogeny led to the development of the Sverdrup Basin.

Gondwana
Much of Gondwana lay in the southern polar region during the Carboniferous. As the plate moved, the South Pole drifted from southern Africa in the early Carboniferous to eastern Antarctica by the end of the period. Glacial deposits are widespread across Gondwana and indicate multiple ice centres and long-distance movement of ice. The northern to northeastern margin of Gondwana (northeast Africa, Arabia, India and northeastern West Australia) was a passive margin along the southern edge of the Paleo-Tethys with cyclothem deposition including, during more temperate intervals, coal swamps in Western Australia. The Mexican terranes along the northwestern Gondwana margin, were affected by the subduction of the Rheic Ocean. However, they lay to west of the Ouachita orogeny and were not impacted by continental collision but became part of the active margin of the Pacific. The Moroccan margin was affected by periods of widespread dextral strike-slip deformation, magmatism and metamorphism associated with the Variscan orogeny.

Towards the end of the Carboniferous, extension and rifting across the northern margin of Gondwana led to the breaking away of the Cimmerian Terrane during the early Permian and the opening of the Neo-Tethys Ocean. Along the southeastern and southern margin of Gondwana (eastern Australia and Antarctica), northward subduction of Panthalassa continued. Changes in the relative motion of the plates resulted in the early Carboniferous Kanimblan Orogeny. Continental arc magmatism continued into the late Carboniferous and extended round to connect with the developing proto-Andean subduction zone along the western South American margin of Gondwana.

Siberia and Amuria
Shallow seas covered much of the Siberian craton in the early Carboniferous. These retreated as sea levels fell in the Pennsylvanian and as the continent drifted north into more temperate zones extensive coal deposits formed in the Kuznetsk Basin. The northwest to eastern margins of Siberia were passive margins along the Mongol-Okhotsk Ocean on the far side of which lay Amuria. From the mid Carboniferous, subduction zones with associated magmatic arcs developed along both margins of the ocean.

The southwestern margin of Siberia was the site of a long lasting and complex accretionary orogen. The Devonian to early Carboniferous Siberian and South Chinese Altai accretionary complexes developed above an east-dipping subduction zone, whilst further south, the Zharma-Saur arc formed along the northeastern margin of Kazakhstania. By the late Carboniferous, all these complexes had accreted to the Siberian craton as shown by the intrusion of post-orogenic granites across the region. As Kazakhstania had already accreted to Laurussia, Siberia was effectively part of Pangea by 310 Ma, although major strike-slip movements continued between it and Laurussia into the Permian.

Central and East Asia
The Kazakhstanian microcontinent is composed of a series of Devonian and older accretionary complexes. It was strongly deformed during the Carboniferous as its western margin collided with Laurussia during the Uralian orogen and its northeastern margin collided with Siberia. Continuing strike-slip motion between Laurussia and Siberia led the formerly elongate microcontinent to bend into an orocline.

During the Carboniferous, the Tarim craton lay along the northwestern edge of North China. Subduction along the Kazakhstanian margin of the Turkestan Ocean resulted in collision between northern Tarim and Kazakhstania during the mid Carboniferous as the ocean closed. The South Tian Shan fold and thrust belt, which extends over 2,000 km from Uzbekistan to northwest China, is the remains of this accretionary complex and forms the suture between Kazakhstania and Tarim. A continental magmatic arc above a south-dipping subduction zone lay along the northern North China margin, consuming the Paleoasian Ocean. Northward subduction of the Paleo-Tethys beneath the southern margins of North China and Tarim continued during the Carboniferous, with the South Qinling block accreted to North China during the mid to late Carboniferous. No sediments are preserved from the early Carboniferous in North China. However, bauxite deposits immediately above the regional mid Carboniferous unconformity indicate warm tropical conditions and are overlain by cyclothems including extensive coals.

South China and Annamia (Southeast Asia) rifted from Gondwana during the Devonian. During the Carboniferous, they were separated from each other and North China by the Paleoasian Ocean with the Paleo-Tethys to the southwest and Panthalassa to the northeast. Cyclothem sediments with coal and evaporites were deposited across the passive margins that surrounded both continents.

Climate
The Carboniferous climate was dominated by the Late Paleozoic Ice Age (LPIA), the most extensive and longest icehouse period of the Phanerozoic, which lasted from the Late Devonian to the Permian (365 Ma-253 Ma). Temperatures began to drop during the late Devonian with a short-lived glaciation in the late Famennian through Devonian–Carboniferous boundary, before the Early Tournaisian Warm Interval. Following this, a reduction in atmospheric CO2 levels, caused by the increased burial of organic matter and widespread ocean anoxia led to climate cooling and glaciation across the south polar region. During the Visean Warm Interval glaciers nearly vanished retreating to the proto-Andes in Bolivia and western Argentina and the Pan-African mountain ranges in southeastern Brazil and southwest Africa.

The main phase of the LPIA (c. 335-290 Ma) began in the late Visean, as the climate cooled and atmospheric CO2 levels dropped. Its onset was accompanied by a global fall in sea level and widespread multimillion-year unconformities. This main phase consisted of a series of discrete several million-year-long glacial periods during which ice expanded out from up to 30 ice centres that stretched across mid- to high latitudes of Gondwana in eastern Australia, northwestern Argentina, southern Brazil, and central and Southern Africa.

Isotope records indicate this drop in CO2 levels was triggered by tectonic factors with increased weathering of the growing Central Pangean Mountains and the influence of the mountains on precipitation and surface water flow. Closure of the oceanic gateway between the Rheic and Tethys oceans in the early Bashkirian also contributed to climate cooling by changing ocean circulation and heat flow patterns.

Warmer periods with reduced ice volume within the Bashkirian, the late Moscovian and the latest Kasimovian to mid-Gzhelian are inferred from the disappearance of glacial sediments, the appearance of deglaciation deposits and rises in sea levels.

In the early Kasimovian there was short-lived (<1 million years) intense period of glaciation, with atmospheric CO2 concentration levels dropping as low as 180 ppm. This ended suddenly as a rapid increase in CO2 concentrations to c. 600 ppm resulted in a warmer climate. This rapid rise in CO2 may have been due to a peak in pyroclastic volcanism and/or a reduction in burial of terrestrial organic matter.

The LPIA peaked across the Carboniferous-Permian boundary. Widespread glacial deposits are found across South America, western and central Africa, Antarctica, Australia, Tasmania, the Arabian Peninsula, India, and the Cimmerian blocks, indicating trans-continental ice sheets across southern Gondwana that reached to sea-level. In response to the uplift and erosion of the more mafic basement rocks of the Central Pangea Mountains at this time, CO2 levels dropped as low as 175 ppm and remained under 400 ppm for 10 Ma.

Temperatures
Temperatures across the Carboniferous reflect the phases of the LPIA. At the extremes, during the Permo-Carboniferous Glacial Maximum (299-293 Ma) the global average temperature (GAT) was c. 13 °C (55 °F), the average temperature in the tropics c. 24 °C (75 °F) and in polar regions c. -23 °C (-10 °F), whilst during the Early Tournaisian Warm Interval (358-353 Ma) the GAT was c. 22 °C (72 °F), the tropics c. 30 °C (86 °F) and polar regions c. 1.5 °C (35 °F). Overall, for the Ice Age the GAT was c. 17 °C (62 °F), with tropical temperatures c. 26 °C and polar temperatures c. -9.0 °C (16 °F).

Atmospheric oxygen levels
There are a variety of methods for reconstructing past atmospheric oxygen levels, including the charcoal record, halite gas inclusions, burial rates of organic carbon and pyrite, carbon isotopes of organic material, isotope mass balance and forward modelling. Results from these different methods for the Carboniferous vary. For example, the increasing occurrence of charcoal produced by wildfires from the Late Devonian into the early Carboniferous indicates increasing oxygen levels, with calculations showing oxygen levels above 21% for much of the Carboniferous, whilst halite gas inclusions from the Visean give estimates at c. 15.3%, although with large uncertainties. Combined results from the different methods, to give an estimate of atmospheric oxygen levels, show levels climbed rapidly from c. 20% at the start of the Carboniferous to c. 30% by its end. The rise in atmospheric oxygen is attributed to the increased burial of organic matter in the widespread coal swamps.

Effects of climate on sedimentation
The changing climate was reflected in regional-scale changes in sedimentation patterns. In the relatively warm waters of the Early to Middle Mississippian, carbonate production occurred to depth across the gently dipping continental slopes of Laurussia and North and South China (carbonate ramp architecture) and evaporites formed around the coastal regions of Laurussia, Kazakhstania, and northern Gondwana.

From the late Visean, the cooling climate restricted carbonate production to depths of less than c. 10 m forming carbonate shelves with flat-tops and steep sides. By the Moscovian, the waxing and waning of the ice sheets led to cyclothem deposition with mixed carbonate-siliciclastic sequences deposited on continental platforms and shelves.

Seasonal melting of glaciers resulted in near freezing waters around the margins of Gondwana. This is evidenced by the occurrence of glendonite (a pseudomorph of ikaite; a form of calcite deposited in glacial waters) in fine-grained, shallow marine sediments.

The glacial grinding and erosion of siliciclastic rocks across Gondwana and the Central Pangaean Mountains produced vast amounts of silt-sized sediment. Redistributed by the wind, this formed widespread deposits of loess across equatorial Pangea.

Effects of climate on biodiversity
The main phase of the LPIA was considered a crisis for marine biodiversity with the loss of many genera, followed by low biodiversity. However, recent studies of marine life suggest the rapid climate and environmental changes that accompanied the onset of the main glacial phase resulted in an adaptive radiation with a rapid increase in the number of species.

The oscillating climate conditions also led to repeated restructuring of Laurasian tropical forests between wetlands and seasonally dry ecosystems, and the appearance and diversification of tetrapods species. There was a major restructuring of wetland forests during the Kasimovian glacial interval, with the loss of arborescent (tree-like) lycopisids and other wetland groups, and a general decline in biodiversity. These events are attributed to the drop in CO2 levels below 400 ppm. Although referred to as the Carboniferous rainforest collapse, this was a complex replacement of one type of rainforest by another, not a complete disappearance of rainforest vegetation.

Across the Carboniferous–Permian boundary interval, a rapid drop in CO2 levels and increasingly arid conditions at low-latitudes led to a permanent shift to seasonally dry woodland vegetation. Tetrapods acquired new terrestrial adaptations and there was a radiation of dryland-adapted amniotes.

Geochemistry
As the continents assembled to form Pangea, the growth of the Central Pangean Mountains led to increased weathering and carbonate sedimentation on the ocean floor, whilst the distribution of continents across the paleo-tropics meant vast areas of land were available for the spread of tropical rainforests. Together these two factors significantly increased CO2 drawdown from the atmosphere, lowering global temperatures, increasing ocean pH and triggering the Late Paleozoic Ice Age. The growth of the supercontinent also changed seafloor spreading rates and led to a decrease in the length and volume of mid-ocean ridge systems.

Magnesium/calcium isotope ratios in seawater
During the early Carboniferous, the Mg2+/Ca2+ ratio in seawater began to rise and by the Middle Mississippian aragonite seas had replaced calcite seas. The concentration of calcium in seawater is largely controlled by ocean pH, and as this increased the calcium concentration was reduced. At the same time, the increase in weathering, increased the amount of magnesium entering the marine environment. As magnesium is removed from seawater and calcium added along mid-ocean ridges where seawater reacts with the newly formed lithosphere, the reduction in length of mid-ocean ridge systems increased the Mg2+/Ca2+ ratio further. The Mg2+/Ca2+ ratio of the seas also affects the ability of organisms to biomineralize. The Carboniferous aragonite seas favoured those that secreted aragonite and the dominant reef builders of the time were aragonitic sponges and corals.

Strontium isotopic composition of seawater
The strontium isotopic composition (87Sr/86Sr) of seawater represents a mix of strontium derived from continental weathering which is rich in 87Sr and from mantle sources e.g. mid-ocean ridges, which are relatively depleted in 87Sr. 87Sr/86Sr ratios above 0.7075 indicate continental weathering is the main source of 87Sr, whilst ratios below indicate mantle-derived sources are the principal contributor.

87Sr/86Sr values varied through the Carboniferous, although they remained above 0.775, indicating continental weathering dominated as the source of 87Sr throughout. The 87Sr/86Sr during the Tournaisian was c. 0.70840, it decreased through the Visean to 0.70771 before increasing during the Serpukhovian to the lowermost Gzhelian where it plateaued at 0.70827, before decreasing again to 0.70814 at the Carboniferous-Permian boundary. These variations reflect the changing influence of weathering and sediment supply to the oceans of the growing Central Pangean Mountains. By the Serpukhovian basement rocks, such as granite, had been uplifted and exposed to weathering. The decline towards the end of the Carboniferous is interpreted as a decrease in continental weathering due to the more arid conditions.

Oxygen and carbon isotope ratios in seawater
Unlike Mg2+/Ca2+ and 87Sr/86Sr isotope ratios, which are consistent across the world's oceans at any one time, δ18O and δ13C preserved in the fossil record can be affected by regional factors. Carboniferous δ18O and δ13C records show regional differences between the South China open-water setting and the epicontinental seas of Laurussia. These differences are due to variations in seawater salinity and evaporation between epicontinental seas relative to the more open waters. However, large scale trends can still be determined. δ13C rose rapidly from c. 0 to 1‰ (parts per thousand) to c. 5 to 7‰ in the Early Mississippian and remained high for the duration of the Late Paleozoic Ice Age (c. 3–6‰) into the early Permian. Similarly from the Early Mississippian there was a long-term increase in δ18O values as the climate cooled.

Both δ13C and δ18O records show significant global isotope changes (known as excursions) during the Carboniferous. The mid-Tournaisian positive δ13C and δ18O excursions lasted between 6 and 10 million years and were also accompanied by c. 6‰ positive excursion in organic matter δ15N values, a negative excursion in carbonate δ238U and a positive excursion in carbonate-associated sulphate δ34S. These changes in seawater geochemistry are interpreted as a decrease in atmospheric CO2 due to increased organic matter burial and widespread ocean anoxia triggering climate cooling and onset of glaciation.

The Mississippian-Pennsylvanian boundary positive δ18O excursion occurred at the same time as global sea level falls and widespread glacial deposits across southern Gondwana, indicating climate cooling and ice build-up. The rise in 87Sr/86Sr just before the δ18O excursion suggests climate cooling in this case was caused by increased continental weathering of the growing Central Pangean Mountains and the influence of the orogeny on precipitation and surface water flow rather than increased burial of organic matter. δ13C values show more regional variation, and it is unclear whether there is a positive δ13C excursion or a readjustment from previous lower values.

During the early Kasimovian there was a short (<1myr), intense glacial period, which came to a sudden end as atmospheric CO2 concentrations rapidly rose. There was a steady increase in arid conditions across tropical regions and a major reduction in the extent of tropical rainforests, as shown by the widespread loss of coal deposits from this time. The resulting reduction in productivity and burial of organic matter led to increasing atmospheric CO2 levels, which were recorded by a negative δ13C excursion and an accompanying, but smaller decrease in δ18O values.

Plants
Early Carboniferous land plants, some of which were preserved in coal balls, were very similar to those of the preceding Late Devonian, but new groups also appeared at this time. The main early Carboniferous plants were the Equisetales (horse-tails), Sphenophyllales (scrambling plants), Lycopodiales (club mosses), Lepidodendrales (scale trees), Filicales (ferns), Medullosales (informally included in the "seed ferns", an assemblage of a number of early gymnosperm groups) and the Cordaitales. These continued to dominate throughout the period, but during the late Carboniferous, several other groups, Cycadophyta (cycads), the Callistophytales (another group of "seed ferns"), and the Voltziales, appeared. The Carboniferous lycophytes of the order Lepidodendrales, which are cousins (but not ancestors) of the tiny club-moss of today, were huge trees with trunks 30 meters high and up to 1.5 meters in diameter. These included Lepidodendron (with its cone called Lepidostrobus), Anabathra, Lepidophloios and Sigillaria. The roots of several of these forms are known as Stigmaria. Unlike present-day trees, their secondary growth took place in the cortex, which also provided stability, instead of the xylem. The Cladoxylopsids were large trees, that were ancestors of ferns, first arising in the Carboniferous.

The fronds of some Carboniferous ferns are almost identical with those of living species. Probably many species were epiphytic. Fossil ferns and "seed ferns" include Pecopteris, Cyclopteris, Neuropteris, Alethopteris, and Sphenopteris; Megaphyton and Caulopteris were tree ferns.

The Equisetales included the common giant form Calamites, with a trunk diameter of 30 to 60 cm and a height of up to 20 m. Sphenophyllum was a slender climbing plant with whorls of leaves, which was probably related both to the calamites and the lycopods.

Cordaites, a tall plant (6 to over 30 meters) with strap-like leaves, was related to the cycads and conifers; the catkin-like reproductive organs, which bore ovules/seeds, is called Cardiocarpus. These plants were thought to live in swamps. True coniferous trees (Walchia, of the order Voltziales) appear later in the Carboniferous, and preferred higher drier ground.

Marine invertebrates
In the oceans the marine invertebrate groups are the Foraminifera, corals, Bryozoa, Ostracoda, brachiopods, ammonoids, hederelloids, microconchids and echinoderms (especially crinoids). The diversity of brachiopods and fusilinid foraminiferans, surged beginning in the Visean, continuing through the end of the Carboniferous, although cephalopod and nektonic conodont diversity declined. This evolutionary radiation was known as the Carboniferous-Earliest Permian Biodiversification Event. For the first time foraminifera took a prominent part in the marine faunas. The large spindle-shaped genus Fusulina and its relatives were abundant in what is now Russia, China, Japan, North America; other important genera include Valvulina, Endothyra, Archaediscus, and Saccammina (the latter common in Britain and Belgium). Some Carboniferous genera are still extant. The first true priapulids appeared during this period.

The microscopic shells of radiolarians are found in cherts of this age in the Culm of Devon and Cornwall, and in Russia, Germany and elsewhere. Sponges are known from spicules and anchor ropes, and include various forms such as the Calcispongea Cotyliscus and Girtycoelia, the demosponge Chaetetes, and the genus of unusual colonial glass sponges Titusvillia. Both reef-building and solitary corals diversify and flourish; these include both rugose (for example, Caninia, Corwenia, Neozaphrentis), heterocorals, and tabulate (for example, Chladochonus, Michelinia) forms. Conularids were well represented by Conularia

Bryozoa are abundant in some regions; the fenestellids including Fenestella, Polypora, and Archimedes, so named because it is in the shape of an Archimedean screw. Brachiopods are also abundant; they include productids, some of which reached very large for brachiopods size and had very thick shells (for example, the 30 cm-wide Gigantoproductus ), while others like Chonetes were more conservative in form. Athyridids, spiriferids, rhynchonellids, and terebratulids are also very common. Inarticulate forms include Discina and Crania. Some species and genera had a very wide distribution with only minor variations.

Annelids such as Serpulites are common fossils in some horizons. Among the mollusca, the bivalves continue to increase in numbers and importance. Typical genera include Aviculopecten, Posidonomya, Nucula, Carbonicola, Edmondia, and Modiola. Gastropods are also numerous, including the genera Murchisonia, Euomphalus, Naticopsis. Nautiloid cephalopods are represented by tightly coiled nautilids, with straight-shelled and curved-shelled forms becoming increasingly rare. Goniatite ammonoids such as Aenigmatoceras are common.

Trilobites are rarer than in previous periods, on a steady trend towards extinction, represented only by the proetid group. Ostracoda, a class of crustaceans, were abundant as representatives of the meiobenthos; genera included Amphissites, Bairdia, Beyrichiopsis, Cavellina, Coryellina, Cribroconcha, Hollinella, Kirkbya, Knoxiella, and Libumella. Crinoids were highly numerous during the Carboniferous, though they suffered a gradual decline in diversity during the Middle Mississippian. Dense submarine thickets of long-stemmed crinoids appear to have flourished in shallow seas, and their remains were consolidated into thick beds of rock. Prominent genera include Cyathocrinus, Woodocrinus, and Actinocrinus. Echinoids such as Archaeocidaris and Palaeechinus were also present. The blastoids, which included the Pentreinitidae and Codasteridae and superficially resembled crinoids in the possession of long stalks attached to the seabed, attain their maximum development at this time.

Freshwater and lagoonal invertebrates
Freshwater Carboniferous invertebrates include various bivalve molluscs that lived in brackish or fresh water, such as Anthraconaia, Naiadites, and Carbonicola; diverse crustaceans such as Candona, Carbonita, Darwinula, Estheria, Acanthocaris, Dithyrocaris, and Anthrapalaemon. The eurypterids were also diverse, and are represented by such genera as Adelophthalmus, Megarachne (originally misinterpreted as a giant spider, hence its name) and the specialised very large Hibbertopterus. Many of these were amphibious. Frequently a temporary return of marine conditions resulted in marine or brackish water genera such as Lingula, Orbiculoidea, and Productus being found in the thin beds known as marine bands.

Terrestrial invertebrates
Fossil remains of air-breathing insects, myriapods and arachnids are known from the Carboniferous. Their diversity when they do appear, however, shows that these arthropods were both well-developed and numerous. Some arthropods grew to large sizes with the up to 2.6 m millipede-like Arthropleura being the largest-known land invertebrate of all time. Among the insect groups are the huge predatory Protodonata (griffinflies), among which was Meganeura, a giant dragonfly-like insect and with a wingspan of ca. 75 cm—the largest flying insect ever to roam the planet. Further groups are the Syntonopterodea (relatives of present-day mayflies), the abundant and often large sap-sucking Palaeodictyopteroidea, the diverse herbivorous Protorthoptera, and numerous basal Dictyoptera (ancestors of cockroaches).

Many insects have been obtained from the coalfields of Saarbrücken and Commentry, and from the hollow trunks of fossil trees in Nova Scotia. Some British coalfields have yielded good specimens: Archaeoptilus, from the Derbyshire coalfield, had a large wing with 4.3 cm preserved part, and some specimens (Brodia) still exhibit traces of brilliant wing colors. In the Nova Scotian tree trunks land snails (Archaeozonites, Dendropupa) have been found.

Fish
Many fish inhabited the Carboniferous seas; predominantly Elasmobranchs (sharks and their relatives). These included some, like Psammodus, with crushing pavement-like teeth adapted for grinding the shells of brachiopods, crustaceans, and other marine organisms. Other groups of elasmobranchs, like the ctenacanthiformes grew to large sizes, with some genera like Saivodus reaching around 6–9 meters (20–30 feet). Other fish had piercing teeth, such as the Symmoriida; some, the petalodonts, had peculiar cycloid cutting teeth. Most of the other cartilaginous fish were marine, but others like the Xenacanthida, and several genera like Bandringa invaded fresh waters of the coal swamps. Among the bony fish, the Palaeonisciformes found in coastal waters also appear to have migrated to rivers. Sarcopterygian fish were also prominent, and one group, the Rhizodonts, reached very large size.

Most species of Carboniferous marine fish have been described largely from teeth, fin spines and dermal ossicles, with smaller freshwater fish preserved whole. Freshwater fish were abundant, and include the genera Ctenodus, Uronemus, Acanthodes, Cheirodus, and Gyracanthus. Chondrichthyes (especially holocephalans like the Stethacanthids) underwent a major evolutionary radiation during the Carboniferous. It is believed that this evolutionary radiation occurred because the decline of the placoderms at the end of the Devonian caused many environmental niches to become unoccupied and allowed new organisms to evolve and fill these niches. As a result of the evolutionary radiation Carboniferous holocephalans assumed a wide variety of bizarre shapes including Stethacanthus which possessed a flat brush-like dorsal fin with a patch of denticles on its top. Stethacanthus unusual fin may have been used in mating rituals.

Other groups like the eugeneodonts filled in the niches left by large predatory placoderms. These fish were unique as they only possessed one row of teeth in their upper or lower jaws in the form of elaborate tooth whorls. The first members of the helicoprionidae, a family eugeneodonts that were characterized by the presence of one circular tooth whorl in the lower jaw, appeared during the early Carboniferous. Perhaps the most bizarre radiation of holocephalans at this time was that of the iniopterygiformes, an order of holocephalans that greatly resembled modern day flying fish that could have also "flown" in the water with their massive, elongated pectoral fins. They were further characterized by their large eye sockets, club-like structures on their tails, and spines on the tips of their fins.

Tetrapods
Carboniferous amphibians were diverse and common by the middle of the period, more so than they are today; some were as long as 6 meters, and those fully terrestrial as adults had scaly skin. They included basal tetrapod groups classified in early books under the Labyrinthodontia. These had a long body, a head covered with bony plates, and generally weak or undeveloped limbs. The largest were over 2 meters long. They were accompanied by an assemblage of smaller amphibians included under the Lepospondyli, often only about 15 cm long. Some Carboniferous amphibians were aquatic and lived in rivers (Loxomma, Eogyrinus, Proterogyrinus); others may have been semi-aquatic (Ophiderpeton, Amphibamus, Hyloplesion) or terrestrial (Dendrerpeton, Tuditanus, Anthracosaurus).

The Carboniferous rainforest collapse slowed the evolution of amphibians who could not survive as well in the cooler, drier conditions. Amniotes, however, prospered because of specific key adaptations. One of the greatest evolutionary innovations of the Carboniferous was the amniote egg, which allowed the laying of eggs in a dry environment, as well as keratinized scales and claws, allowing for the further exploitation of the land by certain tetrapods. These included the earliest sauropsid reptiles (Hylonomus), and the earliest known synapsid (Archaeothyris). Synapsids quickly became huge and diversified in the Permian, only for their dominance to stop during the Mesozoic. Sauropsids (reptiles, and also, later, birds) also diversified but remained small until the Mesozoic, during which they dominated the land, as well as the water and sky, only for their dominance to stop during the Cenozoic.

Reptiles underwent a major evolutionary radiation in response to the drier climate that preceded the rainforest collapse. By the end of the Carboniferous amniotes had already diversified into a number of groups, including several families of synapsid pelycosaurs, protorothyridids, captorhinids, saurians and araeoscelids.

Fungi
As plants and animals were growing in size and abundance in this time, land fungi diversified further. Marine fungi still occupied the oceans. All modern classes of fungi were present in the late Carboniferous.

Romer's gap
The first 15 million years of the Carboniferous had very limited terrestrial fossils. While it has long been debated whether the gap is a result of fossilisation or relates to an actual event, recent work indicates there was a drop in atmospheric oxygen levels, indicating some sort of ecological collapse. The gap saw the demise of the Devonian fish-like ichthyostegalian labyrinthodonts and the rise of the more advanced temnospondylian and reptiliomorphan amphibians that so typify the Carboniferous terrestrial vertebrate fauna.

Carboniferous rainforest collapse
Before the end of the Carboniferous, an extinction event occurred. On land this event is referred to as the Carboniferous rainforest collapse. Vast tropical rainforests collapsed suddenly as the climate changed from hot and humid to cool and arid. This was likely caused by intense glaciation and a drop in sea levels. The new climatic conditions were not favorable to the growth of rainforest and the animals within them. Rainforests shrank into isolated islands, surrounded by seasonally dry habitats. Towering lycopsid forests with a heterogeneous mixture of vegetation were replaced by much less diverse tree fern dominated flora.

Amphibians, the dominant vertebrates at the time, fared poorly through this event with large losses in biodiversity; reptiles continued to diversify through key adaptations that let them survive in the drier habitat, specifically the hard-shelled egg and scales, both of which retain water better than their amphibian counterparts.

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title: Carboniferous


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Comoros

The Comoros, officially the Union of the Comoros, is an archipelagic country made up of three islands in Southeastern Africa, located at the northern end of the Mozambique Channel in the Indian Ocean. Its capital and largest city is Moroni. The religion of the majority of the population, and the official state religion, is Sunni Islam. Comoros proclaimed its independence from France on 6 July 1975. The Comoros is the only country of the Arab League which is entirely in the Southern Hemisphere. It is a member state of the African Union, the Organisation internationale de la Francophonie, the Organisation of Islamic Co-operation, and the Indian Ocean Commission. The country has three official languages: Shikomori, French and Arabic.

At 1659 km2, the Comoros is the third-smallest African country by area. In 2019, its population was estimated to be 850,886. The sovereign state consists of three major islands and numerous smaller islands, all of the volcanic Comoro Islands with the exception of Mayotte. Mayotte voted against independence from France in a referendum in 1974, and continues to be administered by France as an overseas department. France has vetoed a United Nations Security Council resolution that would have affirmed Comorian sovereignty over the island. Mayotte became an overseas department and a region of France in 2011 following a referendum which was passed overwhelmingly.

The Comoros were likely first settled by Austronesian/Malagasy peoples, Bantu speakers from East Africa, and seafaring Arab traders. It became part of the French colonial empire during the 19th century, before its independence in 1975. It has experienced more than 20 coups or attempted coups, with various heads of state assassinated. Along with this constant political instability, it has one of the highest levels of income inequality of any nation, and ranks in the medium quartile on the Human Development Index. Between 2009 and 2014, about 19% of the population lived below the international poverty line of US$1.90 a day by purchasing power parity.

Etymology
The name "Comoros" derives from the Arabic word قمر qamar ("moon").

Settlement

According to mythology, a jinni (spirit) dropped a jewel, which formed a great circular inferno. This became the Karthala volcano, which created the island of Ngazidja (Grande Comore). King Solomon is also said to have visited the island accompanied by his queen Bilqis.

The first attested human inhabitants of the Comoro Islands are now thought to have been Austronesian settlers travelling by boat from islands in Southeast Asia. These people arrived in the area no later than the eighth century AD, the date of the earliest known archaeological site, found on Mayotte, although settlement beginning in the first century has been postulated.

Subsequent settlers came from the east coast of Africa, the Arabian Peninsula and the Persian Gulf, the Malay Archipelago, and Madagascar. Bantu-speaking settlers were present on the islands from the beginnings of settlement [dates?], probably brought to the islands as slaves.

Development of the Comoros is divided into phases. The earliest reliably recorded phase is the Dembeni phase (eighth to tenth centuries), during which there were several small settlements on each island. From the eleventh to the fifteenth centuries, trade with the island of Madagascar and merchants from the Swahili coast and the Middle East flourished, more villages were founded and existing villages grew. Settlers from the Arabian peninsula, particularly Hadhramaut, arrived during this period.

Medieval Comoros
According to legend, in 632, upon hearing of Islam, islanders are said to have dispatched an emissary, Mtswa-Mwindza, to Mecca—but by the time he arrived there, the Islamic prophet Muhammad had died. Nonetheless, after a stay in Mecca, he returned to Ngazidja, where he built a mosque in his home town of Ntsaweni, and led the gradual conversion of the islanders to Islam.

In 933, the Comoros was referred to by Omani sailors as the Perfume Islands.

Among the earliest accounts of East Africa, the works of Al-Masudi describe early Islamic trade routes, and how the coast and islands were frequently visited by Muslims including Persian and Arab merchants and sailors in search of coral, ambergris, ivory, tortoiseshell, gold and slaves. They also brought Islam to the people of the Zanj including the Comoros. As the importance of the Comoros grew along the East African coast, both small and large mosques were constructed. The Comoros are part of the Swahili cultural and economic complex and the islands became a major hub of trade and an important location in a network of trading towns that included Kilwa, in present-day Tanzania, Sofala (an outlet for Zimbabwean gold), in Mozambique, and Mombasa in Kenya.

The Portuguese arrived in the Indian Ocean at the end of the 15th century and the first Portuguese visit to the islands seems to have been that of Vasco da Gama's second fleet in 1503. For much of the 16th century the islands provided provisions to the Portuguese fort at Mozambique and although there was no formal attempt by the Portuguese crown to take possession, a number of Portuguese traders settled and married local women.

By the end of the 16th century local rulers on the African mainland were beginning to push back and, with the support of the Omani Sultan Saif bin Sultan they began to defeat the Dutch and the Portuguese. One of his successors, Said bin Sultan, increased Omani Arab influence in the region, moving his administration to nearby Zanzibar, which came under Omani rule. Nevertheless, the Comoros remained independent, and although the three smaller islands were usually politically unified, the largest island, Ngazidja, was divided into a number of autonomous kingdoms (ntsi).

The islands were well placed to meet the needs of Europeans, initially supplying the Portuguese in Mozambique, then ships, particularly the English, on the route to India, and, later, slaves to the plantation islands in the Mascarenes.

European contact and French colonisation

In the last decade of the 18th century, Malagasy warriors, mostly Betsimisaraka and Sakalava, started raiding the Comoros for slaves and the islands were devastated as crops were destroyed and the people were slaughtered, taken into captivity or fled to the African mainland: it is said that by the time the raids finally ended in the second decade of the 19th century only one man remained on Mwali. The islands were repopulated by slaves from the mainland, who were traded to the French in Mayotte and the Mascarenes. On the Comoros, it was estimated in 1865 that as much as 40% of the population consisted of slaves.

France first established colonial rule in the Comoros by taking possession of Mayotte in 1841 when the Sakalava usurper sultan Andriantsoly (also known as Tsy Levalo) signed the Treaty of April 1841, which ceded the island to the French authorities. After its annexation, France attempted to convert Mayotte into a sugar plantation colony.

Meanwhile, Ndzwani (or Johanna as it was known to the British) continued to serve as a way station for English merchants sailing to India and the Far East, as well as American whalers, although the British gradually abandoned it following their possession of Mauritius in 1814, and by the time the Suez Canal opened in 1869 there was no longer any significant supply trade at Ndzwani. Local commodities exported by the Comoros were, in addition to slaves, coconuts, timber, cattle and tortoiseshell. British and American settlers, as well as the island's sultan, established a plantation-based economy that used about one-third of the land for export crops. In addition to sugar on Mayotte, ylang-ylang and other perfume plants, vanilla, cloves, coffee, cocoa beans, and sisal were introduced.

In 1886, Mwali was placed under French protection by its Sultan Mardjani Abdou Cheikh. That same year, Sultan Said Ali of Bambao, one of the sultanates on Ngazidja, placed the island under French protection in exchange for French support of his claim to the entire island, which he retained until his abdication in 1910. In 1908 the four islands were unified under a single administration (Colonie de Mayotte et dépendances) and placed under the authority of the French colonial Governor-General of Madagascar. In 1909, Sultan Said Muhamed of Ndzwani abdicated in favour of French rule and in 1912 the protectorates were abolished and the islands administered as a single colony. Two years later the colony was abolished and the islands became a province of the colony of Madagascar.

Agreement was reached with France in 1973 for the Comoros to become independent in 1978, despite the deputies of Mayotte voting for increased integration with France. A referendum was held on all four of the islands. Three voted for independence by large margins, while Mayotte voted against. On 6 July 1975, however, the Comorian parliament passed a unilateral resolution declaring independence. Ahmed Abdallah proclaimed the independence of the Comorian State (État comorien; دولة القمر) and became its first president. France did not recognise the new state until 31 December, and retained control of Mayotte.

Independence (1975)
The next 30 years were a period of political turmoil. On 3 August 1975, less than one month after independence, president Ahmed Abdallah was removed from office in an armed coup and replaced with United National Front of the Comoros (FNUK) member Said Mohamed Jaffar. Months later, in January 1976, Jaffar was ousted in favour of his Minister of Defence Ali Soilihi.

The population of Mayotte voted against independence from France in three referendums during this period. The first, held on all the islands on 22 December 1974, won 63.8% support for maintaining ties with France on Mayotte; the second, held in February 1976, confirmed that vote with an overwhelming 99.4%, while the third, in April 1976, confirmed that the people of Mayotte wished to remain a French territory. The three remaining islands, ruled by President Soilihi, instituted a number of socialist and isolationist policies that soon strained relations with France. On 13 May 1978, Bob Denard, once again commissioned by the French intelligence service (SDECE), returned to overthrow President Soilihi and reinstate Abdallah with the support of the French, Rhodesian and South African governments. Ali Soilihi was captured and executed a few weeks later.

In contrast to Soilihi, Abdallah's presidency was marked by authoritarian rule and increased adherence to traditional Islam and the country was renamed the Federal Islamic Republic of the Comoros (République Fédérale Islamique des Comores; جمهورية القمر الإتحادية الإسلامية). Bob Denard served as Abdallah's first advisor; nicknamed the "Viceroy of the Comoros," he was sometimes considered the real strongman of the regime. Very close to South Africa, which financed his "presidential guard," he allowed Paris to circumvent the international embargo on the apartheid regime via Moroni. He also set up from the archipelago a permanent mercenary corps, called upon to intervene at the request of Paris or Pretoria in conflicts in Africa. Abdallah continued as president until 1989 when, fearing a probable coup, he signed a decree ordering the Presidential Guard, led by Bob Denard, to disarm the armed forces. Shortly after the signing of the decree, Abdallah was allegedly shot dead in his office by a disgruntled military officer, though later sources claim an antitank missile was launched into his bedroom and killed him. Although Denard was also injured, it is suspected that Abdallah's killer was a soldier under his command.

A few days later, Bob Denard was evacuated to South Africa by French paratroopers. Said Mohamed Djohar, Soilihi's older half-brother, then became president, and served until September 1995, when Bob Denard returned and attempted another coup. This time France intervened with paratroopers and forced Denard to surrender. The French removed Djohar to Reunion, and the Paris-backed Mohamed Taki Abdoulkarim became president by election. He led the country from 1996, during a time of labour crises, government suppression, and secessionist conflicts, until his death in November 1998. He was succeeded by Interim President Tadjidine Ben Said Massounde.

The islands of Ndzwani and Mwali declared their independence from the Comoros in 1997, in an attempt to restore French rule. But France rejected their request, leading to bloody confrontations between federal troops and rebels. In April 1999, Colonel Azali Assoumani, Army Chief of Staff, seized power in a bloodless coup, overthrowing the Interim President Massounde, citing weak leadership in the face of the crisis. This was the Comoros' 18th coup, or attempted coup d'état since independence in 1975.

Azali failed to consolidate power and reestablish control over the islands, which was the subject of international criticism. The African Union, under the auspices of President Thabo Mbeki of South Africa, imposed sanctions on Ndzwani to help broker negotiations and effect reconciliation. Under the terms of the Fomboni Accords, signed in December 2001 by the leaders of all three islands, the official name of the country was changed to the Union of the Comoros; the new state was to be highly decentralised and the central union government would devolve most powers to the new island governments, each led by a president. The Union president, although elected by national elections, would be chosen in rotation from each of the islands every five years.

Azali stepped down in 2002 to run in the democratic election of the President of the Comoros, which he won. Under ongoing international pressure, as a military ruler who had originally come to power by force, and was not always democratic while in office, Azali led the Comoros through constitutional changes that enabled new elections. A Loi des compétences law was passed in early 2005 that defines the responsibilities of each governmental body, and is in the process of implementation. The elections in 2006 were won by Ahmed Abdallah Mohamed Sambi, a Sunni Muslim cleric nicknamed the "Ayatollah" for his time spent studying Islam in Iran. Azali honoured the election results, thus allowing the first peaceful and democratic exchange of power for the archipelago.

Colonel Mohammed Bacar, a French-trained former gendarme elected President of Ndzwani in 2001, refused to step down at the end of his five-year mandate. He staged a vote in June 2007 to confirm his leadership that was rejected as illegal by the Comoros federal government and the African Union. On 25 March 2008 hundreds of soldiers from the African Union and the Comoros seized rebel-held Ndzwani, generally welcomed by the population: there have been reports of hundreds, if not thousands, of people tortured during Bacar's tenure. Some rebels were killed and injured, but there are no official figures. At least 11 civilians were wounded. Some officials were imprisoned. Bacar fled in a speedboat to Mayotte to seek asylum. Anti-French protests followed in the Comoros (see 2008 invasion of Anjouan). Bacar was eventually granted asylum in Benin.

Since independence from France, the Comoros experienced more than 20 coups or attempted coups.

Following elections in late 2010, former Vice-president Ikililou Dhoinine was inaugurated as president on 26 May 2011. Dhoinine is the first President of the Comoros from the island of Mwali. Following the 2016 elections, Azali Assoumani, from Ngazidja, became president for a third term. In 2018 Azali held a referendum on constitutional reform that would permit a president to serve two terms. The amendments passed, although the vote was widely contested and boycotted by the opposition, and in April 2019, and to widespread opposition, Azali was re-elected president to serve the first of potentially two five-year terms. In January 2020, the legislative elections in Comoros were dominated by President Azali Assoumani's party, the Convention for the Renewal of the Comoros, CRC. It took an overwhelming majority in the parliament.

In 2021, Comoros signed and ratified the Treaty on the Prohibition of Nuclear Weapons, making it a nuclear-weapon-free state. and in 2023, Comoros was invited as a non-member guest to the G7 summit in Hiroshima. On 18 February 2023 the Comoros assumed the presidency of the African Union.

In January 2024, President Azali Assoumani was re-elected with 63% of the vote in the disputed presidential election.

Geography

The Comoros is formed by Ngazidja (Grande Comore), Mwali (Mohéli) and Ndzwani (Anjouan), three major islands in the Comoros Archipelago, as well as many minor islets. The islands are officially known by their Comorian language names, though international sources still use their French names (given in parentheses above). The capital and largest city, Moroni, is located on Ngazidja. The archipelago is situated in the Indian Ocean, in the Mozambique Channel, between the African coast (nearest to Mozambique and Tanzania) and Madagascar, with no land borders.

At 1659 km2, it is one of the smallest countries in the world. The Comoros also has claim to 320 km2 of territorial seas. The interiors of the islands vary from steep mountains to low hills.

The areas and populations (at the 2017 Census) of the main islands are as follows:

Ngazidja is the largest of the Comoros Archipelago, with an area of 1,024 km2. It is also the most recent island, and therefore has rocky soil. The island's two volcanoes, Karthala (active) and La Grille (dormant), and the lack of good harbours are distinctive characteristics of its terrain. Mwali, with its capital at Fomboni, is the smallest of the four major islands. Ndzwani, whose capital is Mutsamudu, has a distinctive triangular shape caused by three mountain chains – Shisiwani, Nioumakele and Jimilime – emanating from a central peak, Mount Ntingui (1575 m). The islands of the Comoros Archipelago were formed by volcanic activity. Mount Karthala, an active shield volcano located on Ngazidja, is the country's highest point, at 2361 m. It contains the Comoros' largest patch of disappearing rainforest. Karthala is currently one of the most active volcanoes in the world, with a minor eruption in May 2006, and prior eruptions as recently as April 2005 and 1991. In the 2005 eruption, which lasted from 17 to 19 April, 40,000 citizens were evacuated, and the crater lake in the volcano's 3 by caldera was destroyed.

The Comoros also lays claim to the Îles Éparses or Îles éparses de l'océan indien (Scattered Islands in the Indian Ocean) – Glorioso Islands, comprising Grande Glorieuse, Île du Lys, Wreck Rock, South Rock, Verte Rocks (three islets) and three unnamed islets – one of France's overseas districts. The Glorioso Islands were administered by the colonial Comoros before 1975, and are therefore sometimes considered part of the Comoros Archipelago. Banc du Geyser, a former island in the Comoros Archipelago, now submerged, is geographically located in the Îles Éparses, but was annexed by Madagascar in 1976 as an unclaimed territory. The Comoros and France each still view the Banc du Geyser as part of the Glorioso Islands and, thus, part of its particular exclusive economic zone.

Climate
The climate is generally tropical and mild, and the two major seasons are distinguishable by their raininess. The temperature reaches an average of 29 - 30 C in March, the hottest month in the rainy season (called kashkazi/kaskazi [meaning north monsoon], which runs from November to April), and an average low of 19 °C in the cool, dry season (kusi (meaning south monsoon), which proceeds from May to October). The islands are rarely subject to cyclones.

Biodiversity
The Comoros constitute an ecoregion in their own right, Comoros forests. It had a 2018 Forest Landscape Integrity Index mean score of 7.69/10, ranking it 33rd globally out of 172 countries.

In December 1952 a specimen of the West Indian Ocean coelacanth fish was re-discovered off the Comoros coast. The 66 million-year-old species was thought to have been long extinct until its first recorded appearance in 1938 off the South African coast. Between 1938 and 1975, 84 specimens were caught and recorded.

Protected areas
There are six national parks in the Comoros – Karthala, Coelacanth, and Mitsamiouli Ndroudi on Grande Comore, Mount Ntringui and Shisiwani on Anjouan, and Mohéli National Park on Mohéli. Karthala and Mount Ntrigui national parks cover the highest peaks on the respective islands, and Coelacanth, Mitsamiouli Ndroudi, and Shisiwani are marine national parks that protect the island's coastal waters and fringing reefs. Mohéli National Park includes both terrestrial and marine areas.

Government

Politics of the Comoros takes place in a framework of a unitary presidential republic, whereby the President of the Comoros is both head of state and head of government, and of a multi-party system. The Constitution of the Union of the Comoros was ratified by referendum on 23 December 2001, and the islands' constitutions and executives were elected in the following months. It had previously been considered a military dictatorship, and the transfer of power from Azali Assoumani to Ahmed Abdallah Mohamed Sambi in May 2006 was a watershed moment as it was the first peaceful transfer in Comorian history.

Executive power is exercised by the government. Legislative power is vested in both the government and parliament. The preamble of the constitution guarantees an Islamic inspiration in governance, a commitment to human rights, and several specific enumerated rights, democracy, "a common destiny" for all Comorians. Each of the islands (according to Title II of the Constitution) has a great amount of autonomy in the Union, including having their own constitutions (or Fundamental Law), president, and Parliament. The presidency and Assembly of the Union are distinct from each of the islands' governments. The presidency of the Union rotates between the islands. Despite widespread misgivings about the durability of the system of presidential rotation, Ngazidja holds the current presidency rotation, and Azali is President of the Union; Ndzwani is in theory to provide the next president.

Legal system
The Comorian legal system rests on Islamic law, an inherited French (Napoleonic Code) legal code, and customary law (mila na ntsi). Village elders, kadis or civilian courts settle most disputes. The judiciary is independent of the legislative and the executive. The Supreme Court acts as a Constitutional Council in resolving constitutional questions and supervising presidential elections. As High Court of Justice, the Supreme Court also arbitrates in cases where the government is accused of malpractice. The Supreme Court consists of two members selected by the president, two elected by the Federal Assembly, and one by the council of each island.

Political culture
Around 80 percent of the central government's annual budget is spent on the country's complex administrative system which provides for a semi-autonomous government and president for each of the three islands and a rotating presidency for the overarching Union government. A referendum took place on 16 May 2009 to decide whether to cut down the government's unwieldy political bureaucracy. 52.7% of those eligible voted, and 93.8% of votes were cast in approval of the referendum. Following the implementation of the changes, each island's president became a governor and the ministers became councillors.

Foreign relations
In November 1975, the Comoros became the 143rd member of the United Nations. The new nation was defined as comprising the entire archipelago, although the citizens of Mayotte chose to become French citizens and keep their island as a French territory.

The Comoros has repeatedly pressed its claim to Mayotte before the United Nations General Assembly, which adopted a series of resolutions under the caption "Question of the Comorian Island of Mayotte", opining that Mayotte belongs to the Comoros under the principle that the territorial integrity of colonial territories should be preserved upon independence. As a practical matter, however, these resolutions have little effect and there is no foreseeable likelihood that Mayotte will become de facto part of the Comoros without its people's consent. More recently, the Assembly has maintained this item on its agenda but deferred it from year to year without taking action. Other bodies, including the Organization of African Unity, the Movement of Non-Aligned Countries and the Organisation of Islamic Cooperation, have similarly questioned French sovereignty over Mayotte. To close the debate and to avoid being integrated by force in the Union of the Comoros, the population of Mayotte overwhelmingly chose to become an overseas department and a region of France in a 2009 referendum. The new status was effective on 31 March 2011 and Mayotte has been recognised as an outermost region by the European Union on 1 January 2014. This decision legally integrates Mayotte in the French Republic.

The Comoros is a member of the United Nations, the African Union, the Arab League, the World Bank, the International Monetary Fund, the Indian Ocean Commission and the African Development Bank. On 10 April 2008, the Comoros became the 179th nation to accept the Kyoto Protocol to the United Nations Framework Convention on Climate Change. The Comoros signed the UN treaty on the Prohibition of Nuclear Weapons. Azali Assoumani, President of the Comoros and Chair of the African Union, attended the 2023 Russia–Africa Summit in Saint Petersburg.

In May 2013 the Union of the Comoros became known for filing a referral to the Office of the Prosecutor of the International Criminal Court (ICC) regarding the events of "the 31 May 2010 Israeli raid on the Humanitarian Aid Flotilla bound for [the] Gaza Strip". In November 2014 the ICC Prosecutor eventually decided that the events did constitute war crimes but did not meet the gravity standards of bringing the case before ICC.

The emigration rate of skilled workers was about 21.2% in 2000.

Military
The military resources of the Comoros consist of a small standing army and a 500-member police force, as well as a 500-member defence force. A defence treaty with France provides naval resources for protection of territorial waters, training of Comorian military personnel, and air surveillance. France maintains the presence of a few senior officers in the Comoros at government request, as well as a small maritime base and a Foreign Legion Detachment (DLEM) on Mayotte.

Once the new government was installed in May–June 2011, an expert mission from UNREC (Lomé) came to the Comoros and produced guidelines for the elaboration of a national security policy, which were discussed by different actors, notably the national defence authorities and civil society. By the end of the programme in end March 2012, a normative framework agreed upon by all entities involved in SSR will have been established. This will then have to be adopted by Parliament and implemented by the authorities.

Human rights
Both male and female same-sex sexual acts are illegal in Comoros. Such acts are punished with up to five years' imprisonment.

Economy

The level of poverty in the Comoros is high, but "judging by the international poverty threshold of $1.9 per person per day, only two out of every ten Comorians could be classified as poor, a rate that places the Comoros ahead of other low-income countries and 30 percentage points ahead of other countries in Sub-Saharan Africa." Poverty declined by about 10% between 2014 and 2018, and living conditions generally improved. Economic inequality remains widespread, with a major gap between rural and urban areas. Remittances through the sizable Comorian diaspora form a substantial part of the country's GDP and have contributed to decreases in poverty and increases in living standards.

According to ILO's ILOSTAT statistical database, between 1991 and 2019 the unemployment rate as a percent of the total labor force ranged from 4.38% to 4.3%. An October 2005 paper by the Comoros Ministry of Planning and Regional Development, however, reported that "registered unemployment rate is 14.3 percent, distributed very unevenly among and within the islands, but with marked incidence in urban areas."

In 2019, more than 56% of the labor force was employed in agriculture, with 29% employed in industry and 14% employed in services. The islands' agricultural sector is based on the export of spices, including vanilla, cinnamon, and cloves, and thus susceptible to price fluctuations in the volatile world commodity market for these goods. The Comoros is the world's largest producer of ylang-ylang, a plant whose extracted essential oil is used in the perfume industry; some 80% of the world's supply comes from the Comoros.

High population densities, as much as 1000 per square kilometre in the densest agricultural zones, for what is still a mostly rural, agricultural economy may lead to an environmental crisis in the near future, especially considering the high rate of population growth. In 2004 the Comoros' real GDP growth was a low 1.9% and real GDP per capita continued to decline. These declines are explained by factors including declining investment, drops in consumption, rising inflation, and an increase in trade imbalance due in part to lowered cash crop prices, especially vanilla.

Fiscal policy is constrained by erratic fiscal revenues, a bloated civil service wage bill, and an external debt that is far above the HIPC threshold. Membership in the franc zone, the main anchor of stability, has nevertheless helped contain pressures on domestic prices.

The Comoros has an inadequate transportation system, a young and rapidly increasing population, and few natural resources. The low educational level of the labour force contributes to a subsistence level of economic activity, high unemployment, and a heavy dependence on foreign grants and technical assistance. Agriculture contributes 40% to GDP and provides most of the exports.

The government is struggling to upgrade education and technical training, to privatise commercial and industrial enterprises, to improve health services, to diversify exports, to promote tourism, and to reduce the high population growth rate.

The Comoros is a member of the Organization for the Harmonization of Business Law in Africa (OHADA).

Demographics
With about 850,000 residents, the Comoros is one of the least populous countries in the world, but its population density is high, with an average of 275 PD/km2. In 2001, 34% of the population was considered urban, but the urban population has since grown; in recent years rural population growth has been negative, while overall population growth is still relatively high. In 1958 the population was 183,133.

In 2009, almost half the population of the Comoros was under the age of 15. Major urban centres include Moroni, Mitsamihuli, Foumbouni, Mutsamudu, Domoni, and Fomboni. There are between 200,000 and 350,000 Comorians in France.

Ethnic groups
The islands of the Comoros are 97.1% ethnically Comorian, which is a mixture of Bantu, Malagasy, and Arab people. Minorities include Makua and Indian (mostly Ismaili). There are recent immigrants of Chinese origin in Grande Comore (especially Moroni). Although most French left after independence in 1975, a small Creole community, descended from settlers from France, Madagascar and Réunion, lives in the Comoros.

Languages
The most common languages in the Comoros are the Comorian languages, collectively known as Shikomori. They are related to Swahili, and the four different variants (Shingazidja, Shimwali, Shindzwani and Shimaore) are spoken on each of the four islands. Arabic and Latin scripts are both used, Arabic being the more widely used, and an official orthography has recently been developed for the Latin script.

Arabic and French are also official languages, along with Comorian. Arabic is widely known as a second language, being the language of Quranic teaching. French is the administrative language and the language of most non-Quranic formal education.

Religion
Sunni Islam is the dominant religion, followed by as much as 99% of the population. Comoros is the only Muslim-majority country in Southern Africa and one of the three southernmost Muslim-majority territories, along with Mayotte and the Australian territory of Cocos Islands. A minority of the population of the Comoros are Christian, both Catholic and Protestant denominations are represented, and most Malagasy residents are also Christian. Immigrants from metropolitan France are mostly Catholic.

Health
There are 15 physicians per 100,000 people. The fertility rate was 4.7 per adult woman in 2004. Life expectancy at birth is 67 for females and 62 for males.

Education
Almost all children attend Quranic schools, usually before, although increasingly in tandem with regular schooling. Children are taught about the Qur'an, and memorise it, and learn the Arabic script. Most parents prefer their children to attend Koran schools before moving on to the French-based schooling system. Although the state sector is plagued by a lack of resources, and the teachers by unpaid salaries, there are numerous private and community schools of relatively good standard. The national curriculum, apart from a few years during the revolutionary period immediately post-independence, has been very much based on the French system, both because resources are French and most Comorians hope to go on to further education in France. There have recently been moves to Comorianise the syllabus and integrate the two systems, the formal and the Quran schools, into one, thus moving away from the secular educational system inherited from France.

Pre-colonization education systems in Comoros focused on necessary skills such as agriculture, caring for livestock and completing household tasks. Religious education also taught Islam. The education system underwent a transformation during colonization in the early 1900s which brought secular education based on the French system. This was mainly for children of the elite. After Comoros gained independence in 1975, the education system changed again. Funding for teachers' salaries was lost, and many went on strike. Thus, the public education system was not functioning between 1997 and 2001. Since gaining independence, the education system has also undergone a democratization and options exist for those other than the elite. Enrollment has also grown.

In 2000, 44.2% of children aged 5 to 14 years were attending school. There is a general lack of facilities, equipment, qualified teachers, textbooks and other resources. Salaries for teachers are often so far in arrears that many refuse to work.

Prior to 2000, students seeking a university education had to attend school outside of the country. However, in the early 2000s a university was created in the country. This served to help economic growth and to fight the "flight" of many educated people who were not returning to the islands to work.

Comorian has no native script, but both the Arabic and Latin alphabets are used. In 2004, about 57 percent of the population was literate in the Latin script while more than 90 percent were literate in the Arabic script.

Culture
Traditionally, women on Ndzwani wear red and white patterned garments called shiromani, while on Ngazidja and Mwali colourful shawls called leso are worn. Many women apply a paste of ground sandalwood and coral called msindzano to their faces. Traditional male clothing is a long white shirt known as a nkandu, and a bonnet called a kofia.

Marriage
There are two types of marriages in Comoros, the little marriage (known as Mna daho on Ngazidja) and the customary marriage (known as ada on Ngazidja, harusi on the other islands). The little marriage is a simple legal marriage. It is small, intimate, and inexpensive, and the bride's dowry is nominal. A man may undertake a number of Mna daho marriages in his lifetime, often at the same time, a woman fewer; but both men and women will usually only undertake one ada, or grand marriage, and this must generally be within the village. The hallmarks of the grand marriage are dazzling gold jewelry, two weeks of celebration and an enormous bridal dowry. Although the expenses are shared between both families as well as with a wider social circle, an ada wedding on Ngazidja can cost up to €50,000. Many couples take a lifetime to save for their ada, and it is not uncommon for a marriage to be attended by a couple's adult children.

The ada marriage marks a man's transition in the Ngazidja age system from youth to elder. His status in the social hierarchy greatly increases, and he will henceforth be entitled to speak in public and participate in the political process, both in his village and more widely across the island. He will be entitled to display his status by wearing a mharuma, a type of shawl, across his shoulders, and he can enter the mosque by the door reserved for elders, and sit at the front. A woman's status also changes, although less formally, as she becomes a "mother" and moves into her own house. The system is less formalised on the other islands, but the marriage is nevertheless a significant and costly event across the archipelago. The ada is often criticized because of its great expense, but at the same time it is a source of social cohesion and the main reason why migrants in France and elsewhere continue to send money home. Increasingly, marriages are also being taxed for the purposes of village development.

Kinship and social structure
Comorian society has a bilateral descent system. Lineage membership and inheritance of immovable goods (land, housing) is matrilineal, passed in the maternal line, similar to many Bantu peoples who are also matrilineal, while other goods and patronymics are passed in the male line. However, there are differences between the islands, the matrilineal element being stronger on Ngazidja.

Music
Twarab music, imported from Zanzibar in the early 20th century, remains the most influential genre on the islands and is popular at ada marriages.

Media
There are two daily national newspapers published in the Comoros, the government-owned Al-Watwan, and the privately owned La Gazette des Comores, both published in Moroni. There are a number of smaller newsletters published on an irregular basis as well as a variety of news websites. The government-owned ORTC (Office de Radio et Télévision des Comores) provides national radio and television service. There is a TV station run by the Anjouan regional government, and regional governments on the islands of Grande Comore and Anjouan each operate a radio station. There are also a few independent and small community radio stations that operate on the islands of Grande Comore and Mohéli, and these two islands have access to Mayotte Radio and French TV.

title: Comoros


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Critical philosophy

The critical philosophy (kritische Philosophie) movement, attributed to Immanuel Kant (1724–1804), sees the primary task of philosophy as criticism rather than justification of knowledge. Criticism, for Kant, meant judging as to the possibilities of knowledge before advancing to knowledge itself (from the Greek kritike (techne), or "art of judgment"). The basic task of philosophers, according to this view, is not to establish and demonstrate theories about reality, but rather to subject all theories—including those about philosophy itself—to critical review, and measure their validity by how well they withstand criticism.

"Critical philosophy" is also used as another name for Kant's philosophy itself. Kant said that philosophy's proper inquiry is not about what is out there in reality, but rather about the character and foundations of experience itself. We must first judge how human reason works, and within what limits, so that we can afterwards correctly apply it to sense experience and determine whether it can be applied at all to metaphysical objects.

The principal three sources on which the critical philosophy is based are the three critiques, namely Critique of Pure Reason, Critique of Practical Reason and Critique of Judgement, published between 1781 and 1790 and mostly concerned, respectively, with metaphysics, ethics and aesthetics.

title: Critical philosophy