Agriculture is the science and art of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities; the history of agriculture began thousands of years ago. After gathering wild grains beginning at least 105,000 years ago, nascent farmers began to plant them around 11,500 years ago. Pigs and cattle were domesticated over 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. Industrial agriculture based on large-scale monoculture in the twentieth century came to dominate agricultural output, though about 2 billion people still depended on subsistence agriculture into the twenty-first. Modern agronomy, plant breeding, agrochemicals such as pesticides and fertilizers, technological developments have increased yields, while causing widespread ecological and environmental damage. Selective breeding and modern practices in animal husbandry have increased the output of meat, but have raised concerns about animal welfare and environmental damage.
Environmental issues include contributions to global warming, depletion of aquifers, antibiotic resistance, growth hormones in industrial meat production. Genetically modified organisms are used, although some are banned in certain countries; the major agricultural products can be broadly grouped into foods, fibers and raw materials. Food classes include cereals, fruits, meat, milk and eggs. Over one-third of the world's workers are employed in agriculture, second only to the service sector, although the number of agricultural workers in developed countries has decreased over the centuries; the word agriculture is a late Middle English adaptation of Latin agricultūra, from ager, "field", which in its turn came from Greek αγρός, cultūra, "cultivation" or "growing". While agriculture refers to human activities, certain species of ant and ambrosia beetle cultivate crops. Agriculture is defined with varying scopes, in its broadest sense using natural resources to "produce commodities which maintain life, including food, forest products, horticultural crops, their related services".
Thus defined, it includes arable farming, animal husbandry and forestry, but horticulture and forestry are in practice excluded. The development of agriculture enabled the human population to grow many times larger than could be sustained by hunting and gathering. Agriculture began independently in different parts of the globe, included a diverse range of taxa, in at least 11 separate centres of origin. Wild grains were eaten from at least 105,000 years ago. From around 11,500 years ago, the eight Neolithic founder crops and einkorn wheat, hulled barley, lentils, bitter vetch, chick peas and flax were cultivated in the Levant. Rice was domesticated in China between 11,500 and 6,200 BC with the earliest known cultivation from 5,700 BC, followed by mung and azuki beans. Sheep were domesticated in Mesopotamia between 11,000 years ago. Cattle were domesticated from the wild aurochs in the areas of modern Turkey and Pakistan some 10,500 years ago. Pig production emerged in Eurasia, including Europe, East Asia and Southwest Asia, where wild boar were first domesticated about 10,500 years ago.
In the Andes of South America, the potato was domesticated between 10,000 and 7,000 years ago, along with beans, llamas and guinea pigs. Sugarcane and some root vegetables were domesticated in New Guinea around 9,000 years ago. Sorghum was domesticated in the Sahel region of Africa by 7,000 years ago. Cotton was domesticated in Peru by 5,600 years ago, was independently domesticated in Eurasia. In Mesoamerica, wild teosinte was bred into maize by 6,000 years ago. Scholars have offered multiple hypotheses to explain the historical origins of agriculture. Studies of the transition from hunter-gatherer to agricultural societies indicate an initial period of intensification and increasing sedentism. Wild stands, harvested started to be planted, came to be domesticated. In Eurasia, the Sumerians started to live in villages from about 8,000 BC, relying on the Tigris and Euphrates rivers and a canal system for irrigation. Ploughs appear in pictographs around 3,000 BC. Farmers grew wheat, vegetables such as lentils and onions, fruits including dates and figs.
Ancient Egyptian agriculture relied on its seasonal flooding. Farming started in the predynastic period at the end of the Paleolithic, after 10,000 BC. Staple food crops were grains such as wheat and barley, alongside industrial crops such as flax and papyrus. In India, wheat and jujube were domesticated by 9,000 BC, soon followed by sheep and goats. Cattle and goats were domesticated in Mehrgarh culture by 8,000–6,000 BC. Cotton was cultivated by the 5th-4th millennium BC. Archeological evidence indicates an animal-drawn plough from 2,500 BC in the Indus Valley Civilisation. In China, from the 5th century BC there was a nationwide granary system and widespread silk farming. Water-powered grain mills were in use followed by irrigation. By the late 2nd century, heavy ploughs had been developed with iron mouldboards; these spread westwards across Eurasia. Asian rice was domesticated 8,200–13,500 years ago – depending on the molecular clock estimate, used – on the Pearl River in southern China with a single genetic origin from the wild rice Oryza rufipogon
A lozenge referred to as a diamond, is a form of rhombus. The definition of lozenge is not fixed, it is sometimes used as a synonym for rhombus. Most though, lozenge refers to a thin rhombus—a rhombus with two acute and two obtuse angles one with acute angles of 45°; the lozenge shape is used in parquetry and as decoration on ceramics and textiles. It features in heraldry and playing cards; the lozenge motif dates as far back as the Neolithic and Paleolithic period in Eastern Europe and represents a sown field and female fertility. The ancient lozenge pattern shows up in Diamond vault architecture, in traditional dress patterns of Slavic peoples, in traditional Ukrainian embroidery; the lozenge pattern appears extensively in Celtic art, art from the Ottoman Empire, ancient Phrygian art. The lozenge symbolism is one of the main female symbols in Berber carpets. Common Berber jewelry from the Aurès Mountains or Kabylie in Algeria uses this pattern as a female fertility sign. In 1658, the English philosopher Sir Thomas Browne published The Garden of Cyrus subtitled The Quincunciall Lozenge, or Network Plantations of the Ancients where he outlined the mystical interconnection of art and the Universe via the quincunx pattern.
He suggested. Lozenges appear as symbols in ancient classic element systems, in amulets, in religious symbolism. In a suit of playing cards, diamonds is in the shape of a lozenge. In Unicode, the lozenge is encoded in multiple variants: U+22C4 ⋄ DIAMOND OPERATOR U+2311 ⌑ SQUARE LOZENGE U+25CA ◊ LOZENGE U+2662 ♢ WHITE DIAMOND SUIT U+2666 ♦ BLACK DIAMOND SUIT U+27E0 ⟠ LOZENGE DIVIDED BY HORIZONTAL RULE U+29EB ⧫ BLACK LOZENGE U+2B27 ⬧ BLACK MEDIUM LOZENGE U+2B28 ⬨ WHITE MEDIUM LOZENGE U+2B2A ⬪ BLACK SMALL LOZENGE U+2B2B ⬫ WHITE SMALL LOZENGE U+25C6 ◆ BLACK DIAMOND U+25C7 ◇ WHITE DIAMOND U+2726 ✦ BLACK FOUR POINTED STAR U+2727 ✧ WHITE FOUR POINTED STAR U+20DF ⃟ COMBINING ENCLOSING DIAMOND The character is present in DOS code page 437 and Mac-Roman; the TeX command for the lozenge is \lozenge. In IBM 026 punched card code the square lozenge variant ⌑ is, In modal logic, the lozenge expresses that there is "possibility." For example, the expression ◊ P expresses. In axiomatic set theory, the lozenge refers to the principles known collectively as the diamond principle.
The APL programming language uses the lozenge, called diamond, as statement separator. On equipment calculators, the lozenge is used to mark the subtotal key, it is standardized in ISO 7000 as symbol ISO-7000-0650. In a similar fashion, the lozenge, part of the BCDIC, was used on tabulation listings to indicate second level totals in banking installations in the 1960s. During the First World War, the Germans developed Lozenge-Tarnung; this camouflage was made up of colored polygons of five colors. The repeating patterns used irregular four-, five- and six-sided polygons, but some contained regular rhombi or hexagons; because painting such a pattern was time consuming, the paint added to the weight of the aircraft, the pattern was printed on fabric. This pre-printed fabric was used from 1916 in various forms and colours; the lozenge in heraldry is a diamond-shaped charge somewhat narrower than it is tall. A mascle is a voided lozenge—that is, a lozenge with a lozenge-shaped hole in the middle—and the rarer rustre is a lozenge containing a circular hole.
A field covered in a pattern of lozenges is described as lozengy. Cough tablets have taken the name lozenge, based on their original shape. According to the Oxford English Dictionary the first use of this sense was in 1530. In Finland, the lozenge is associated through Apteekin Salmiakki. Thus, the lozenge is called salmiakkikuvio "salmiak shape"; the pattern is used if the candy is not lozenge-shaped. To implement 10 U. S. C 773, the Secretary of the Navy has prescribed the following distinctive mark for wear by members of military societies which are composed of honorably discharged officers and enlisted personnel, or by the instructors and members of duly organized cadet corps; the distinctive mark will be a diamond, 3½ inches long by 2 inches wide, of any cloth material. A white distinctive mark will be worn on green, or khaki clothing; the distinctive mark will be worn on all outer clothing on the right sleeve, at the point of the shoulder, the upper tip of the diamond to be ¼ inch below the shoulder seam.
The lozenge is used in the Army, Marine Corps, Air Force on the insignia of their respective first sergeants. It is used in the cadet programs of Army ROTC, Army and Marine Corps Junior ROTC, the Civil Air Patrol as rank insignia of cadet officers corresponding to the military pay grades of O-4 to O-6
Quartzite is a hard, non-foliated metamorphic rock, pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure related to tectonic compression within orogenic belts. Pure quartzite is white to grey, though quartzites occur in various shades of pink and red due to varying amounts of iron oxide. Other colors, such as yellow, green and orange, are due to other minerals; when sandstone is cemented to quartzite, the individual quartz grains recrystallize along with the former cementing material to form an interlocking mosaic of quartz crystals. Most or all of the original texture and sedimentary structures of the sandstone are erased by the metamorphism; the grainy, sandpaper-like surface becomes glassy in appearance. Minor amounts of former cementing materials, iron oxide, silica and clay migrate during recrystallization and metamorphosis; this causes lenses to form within the quartzite. Orthoquartzite is a pure quartz sandstone composed of well-rounded quartz grains cemented by silica.
Orthoquartzite is 99% SiO2 with only minor amounts of iron oxide and trace resistant minerals such as zircon and magnetite. Although few fossils are present, the original texture and sedimentary structures are preserved; the term is traditionally used for quartz-cemented quartz arenites, both usages are found in the literature. The typical distinction between the two is a metamorphic quartzite is so cemented, diagenetically altered, metamorphosized so that it will fracture and break across grain boundaries, not around them. Quartzite is resistant to chemical weathering and forms ridges and resistant hilltops; the nearly pure silica content of the rock provides little material for soil. In the United States, formations of quartzite can be found in some parts of Pennsylvania, the Washington DC area, eastern South Dakota, Central Texas, southwest Minnesota, Devil's Lake State Park in the Baraboo Range in Wisconsin, the Wasatch Range in Utah, near Salt Lake City, Utah and as resistant ridges in the Appalachians and other mountain regions.
Quartzite is found in the Morenci Copper Mine in Arizona. The town of Quartzsite in western Arizona derives its name from the quartzites in the nearby mountains in both Arizona and Southeastern California. A glassy vitreous quartzite has been described from the Belt Supergroup in the Coeur d’Alene district of northern Idaho. In the United Kingdom, a craggy ridge of quartzite called the Stiperstones runs parallel with the Pontesford-Linley fault, 6 km north-west of the Long Mynd in south Shropshire. To be found in England are the Cambrian "Wrekin quartzite", the Cambrian "Hartshill quartzite". In Wales, Holyhead mountain and most of Holy island off Anglesey sport excellent Precambrian quartzite crags and cliffs. In the Scottish Highlands, several mountains composed of Cambrian quartzite can be found in the far north-west Moine Thrust Belt running in a narrow band from Loch Eriboll in a south-westerly direction to Skye. In Ireland areas of quartzite are found across the northwest, with Errigal in Donegal as the most prominent outcrop.
In continental Europe, various regionally isolated quartzite deposits exist at surface level in a belt from the Rhenish Massif and the German Central Highlands into the Western Czech Republic, for example in the Taunus and Harz mountains. In Poland quartzite deposits at surface level exists in Świętokrzyskie Mountains. In Canada, the La Cloche Mountains in Ontario are composed of white quartzite; the highest mountain in Mozambique, Monte Binga, as well as the rest of the surrounding Chimanimani Plateau are composed of hard, pale grey, Precambrian quartzite. Quartzite is mined in Brazil for use in kitchen countertops; because of its hardness and angular shape, crushed quartzite is used as railway ballast. Quartzite is a decorative stone and may be used to cover walls, as roofing tiles, as flooring, stair steps, its use for countertops in kitchens is expanding rapidly. It is more resistant to stains than granite. Crushed quartzite is sometimes used in road construction. High purity quartzite is used to produce ferrosilicon, industrial silica sand and silicon carbide.
During the Paleolithic, quartzite was used, along with flint and other lithic raw materials, for making stone tools. The term quartzite is derived from German: Quarzit. Neomorphism R. V. Dietrich's GemRocks: Quartzite CSU Pomona Geology: Quartzite Cowen's "The First Geologists" Minnesota Department of Natural Resources: Natural History: Minnesota's geology Wisconsin's Baraboo Syncline South Dakota 2002 Mineral Summary: Production and Environmental Issues Big Sioux River: History of Sioux Falls and Quartzite Photos
A canyon or gorge is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic timescales. Rivers have a natural tendency to cut through underlying surfaces wearing away rock layers as sediments are removed downstream. A river bed will reach a baseline elevation, the same elevation as the body of water into which the river drains; the processes of weathering and erosion will form canyons when the river's headwaters and estuary are at different elevations through regions where softer rock layers are intermingled with harder layers more resistant to weathering. A canyon may refer to a rift between two mountain peaks, such as those in ranges including the Rocky Mountains, the Alps, the Himalayas or the Andes. A river or stream and erosion carve out such splits between mountains. Examples of mountain-type canyons are Provo Canyon in Utah or Yosemite Valley in California's Sierra Nevada. Canyons within mountains, or gorges that have an opening on only one side, are called box canyons.
Slot canyons are narrow canyons that have smooth walls. Steep-sided valleys in the seabed of the continental slope are referred to as submarine canyons. Unlike canyons on land, submarine canyons are thought to be formed by turbidity currents and landslides; the word canyon is Spanish in origin, with the same meaning. The word canyon is used in North America while the words gorge and ravine are used in Europe and Oceania, though gorge and ravine are used in some parts of North America. In the United States, place names use canyon in the southwest and gorge in the northeast, with the rest of the country graduating between these two according to geography. In Canada, a gorge is narrow while a ravine is more open and wooded; the military-derived word defile is used in the United Kingdom. Most canyons were formed by a process of long-time erosion from table-land level; the cliffs form because harder rock strata that are resistant to erosion and weathering remain exposed on the valley walls. Canyons are much more common in arid than in wet areas because physical weathering has a more localized effect in arid zones.
The wind and water from the river combine to erode and cut away less resistant materials such as shales. The freezing and expansion of water serves to help form canyons. Water seeps into cracks between the rocks and freezes, pushing the rocks apart and causing large chunks to break off the canyon walls, in a process known as frost wedging. Canyon walls are formed of resistant sandstones or granite. Sometimes large rivers run through canyons as the result of gradual geological uplift; these are called entrenched rivers, because they are unable to alter their course. In the United States, the Colorado River in the Southwest and the Snake River in the Northwest are two examples of tectonic uplift. Canyons form in areas of limestone rock; as limestone is soluble to a certain extent, cave systems form in the rock. When these collapse, a canyon is left, as in the Mendip Hills in Somerset and Yorkshire Dales in Yorkshire, England. A box canyon is a small canyon, shorter and narrower than a river canyon, with steep walls on three sides, allowing access and egress only through the mouth of the canyon.
Box canyons were used in the western United States as convenient corrals, with their entrances fenced. The definition of "largest canyon" is imprecise, because a canyon can be large by its depth, its length, or the total area of the canyon system; the inaccessibility of the major canyons in the Himalaya contributes to their not being regarded as candidates for the biggest canyon. The definition of "deepest canyon" is imprecise if one includes mountain canyons as well as canyons cut through flat plateaus; the Yarlung Tsangpo Grand Canyon, along the Yarlung Tsangpo River in Tibet, is regarded by some as the deepest canyon in the world at 5,500 m. It is longer than the Grand Canyon in the United States. Others consider the Kali Gandaki Gorge in midwest Nepal to be the deepest canyon, with a 6400 m difference between the level of the river and the peaks surrounding it. Vying for deepest canyon in the Americas are the Cotahuasi Canyon and Colca Canyon, in southern Peru. Both have been measured at over 3500 m deep.
The Grand Canyon of northern Arizona in the United States, with an average depth of 1,600 m and a volume of 4.17 trillion cubic metres, is one of the world's largest canyons. It was among the 28 finalists of the New7Wonders of Nature worldwide poll; the largest canyon in Africa is the Fish River Canyon in Namibia. In August 2013, the discovery of Greenland's Grand Canyon was reported, based on the analysis of data from Operation IceBridge, it is located under an ice sheet. At 750 kilometres long, it is believed to be the longest canyon in the world; the Capertee Valley in Australia is reported as being the second largest canyon in the world. Some canyons have notable cultural significance. Evidence of early humanoids has been discovered in Africa's Olduvai Gorge. In the southwestern United States, canyons are important archeologically because of the many cliff-dwellings built in such areas by the ancient Pueblo people who were their first inhabitants; the following list contains only the most notable canyons of the world, arranged by continent and country.
Fish River Canyon Blyde Riv
A valley is a low area between hills or mountains with a river running through it. In geology, a valley or dale is a depression, longer than it is wide; the terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys. Most valleys belong to one of these two main types or a mixture of them, at least with respect to the cross section of the slopes or hillsides. A valley in its broadest geographic sense is known as a dale. Other terms used for valleys are: Vale: A valley. Dell: A small and wooded valley. Glen: A long valley bounded by sloped concave sides. Strath: A wide, flat valley through which a river runs. Mountain cove: A small valley, closed at one or both ends, in the central or southern Appalachian Mountains which sometimes results from the erosion of a geologic window. Hollow: A term used sometimes for a small valley surrounded by mountains or ridges. Cwm: A deep, narrow valley. A steephead valley is a deep, flat bottomed valley with an abrupt ending. Erosional valley: A valley formed by erosion.
Structural valley: A valley formed by geologic events such as drop faults or the rise of highlands. Dry valley: A valley not created by sustained surface water flow. Longitudinal valley: An elongated valley found between two parallel mountain chains. Similar geological structures, such as canyons, gorges, gullies and kloofs, are not referred to as valleys. A valley formed by flowing water, called fluvial valley or river valley, is V-shaped; the exact shape will depend on the characteristics of the stream flowing through it. Rivers with steep gradients, as in mountain ranges, produce a bottom. Shallower slopes may produce gentler valleys. However, in the lowest stretch of a river, where it approaches its base level, it begins to deposit sediment and the valley bottom becomes a floodplain; some broad V examples are: North America: Black Canyon of the Gunnison National Park, others in Grand Canyon NP Europe: Austria: narrow passages of upper Inn valley, affluents of Enns Switzerland: Napf region, Zurich Oberland, Engadin Germany: affluents to the middle reaches of Rhine and MoselSome of the first human complex societies originated in river valleys, such as that of the Nile, Tigris-Euphrates, Ganges, Yellow River and arguably Amazon.
In prehistory, the rivers were used as a source of fresh water and food, as well as a place to wash and a sewer. The proximity of water moderated temperature extremes and provided a source for irrigation, stimulating the development of agriculture. Most of the first civilizations developed from these river valley communities. In geography, a vale is a wide river valley with a wide flood plain or flat valley bottom. In Southern England, vales occur between the escarpment slopes of pairs of chalk formations, where the chalk dome has been eroded, exposing less resistant underlying rock claystone. Rift valleys, such as the Albertine Rift and Gregory Rift are formed by the expansion of the Earth's crust due to tectonic activity beneath the Earth's surface. There are various forms of valley associated with glaciation that may be referred to as glacial valleys. A valley carved by glaciers is U-shaped and resembles a trough; this trough valley becomes visible upon the recession of the glacier. When the ice recedes or thaws, the valley remains littered with small boulders that were transported within the ice.
Floor gradient does not affect the valley's shape, it is the glacier's size. Continuously flowing glaciers – in the ice age – and large-sized glaciers carve wide, deep incised valleys, sometimes with valley steps that reflect differing erosion rates. Examples of U-shaped valleys are found in every mountainous region that has experienced glaciation during the Pleistocene ice ages. Most present U-shaped valleys started as V-shaped before glaciation; the glaciers carved it out wider and deeper changing the shape. This proceeds through the glacial erosion processes of glaciation and abrasion, which results in large rocky material being carried in the glacier. A material called; as the ice melts and retreats, the valley is left with steep sides and a wide, flat floor. A river or stream may remain in the valley; this replaces the original stream or river and is known as a misfit stream because it is smaller than one would expect given the size of its valley. Other interesting glacially carved valleys include: Yosemite Valley Side valleys of the Austrian river Salzach for their parallel directions and hanging mouths.
Some Scottish glens full with flowers. That of the St. Mary River in Glacier National Park in Montana, USA. A tunnel valley is a large, long, U-shaped valley cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and covering portions of all continents during past glacial ages. A tunnel valley can be up to 100 km, 4 km wide, 400 m deep. Tunnel valleys were formed by subglacial erosion by water, they served as subglacial drainage pathways carrying large volumes of melt water. Their cross-sections exhibit steep-sided flanks similar to fjord walls, their flat bottoms are typical of subglacial glacial erosion. In northern Central Europe, the Scandinavian ice sheet during the various ice ages advanced uphill against the lie of the land; as a result, its meltwaters flowed parallel to the ice margin to reach the North Sea basin, formin
The Caribbean Sea is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico and Central America to the west and south west, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, to the south by the north coast of South America; the entire area of the Caribbean Sea, the numerous islands of the West Indies, adjacent coasts, are collectively known as the Caribbean. The Caribbean Sea is one of the largest seas and has an area of about 2,754,000 km2; the sea's deepest point is the Cayman Trough, between the Cayman Islands and Jamaica, at 7,686 m below sea level. The Caribbean coastline has many gulfs and bays: the Gulf of Gonâve, Gulf of Venezuela, Gulf of Darién, Golfo de los Mosquitos, Gulf of Paria and Gulf of Honduras; the Caribbean Sea has the Mesoamerican Barrier Reef. It runs 1,000 km along the coasts of Mexico, Belize and Honduras; the name "Caribbean" derives from the Caribs, one of the region's dominant Native American groups at the time of European contact during the late 15th century.
After Christopher Columbus landed in the Bahamas in 1492, the Spanish term Antillas applied to the lands. During the first century of development, Spanish dominance in the region remained undisputed. From the 16th century, Europeans visiting the Caribbean region identified the "South Sea" as opposed to the "North Sea"; the Caribbean Sea had been unknown to the populations of Eurasia until 1492, when Christopher Columbus sailed into Caribbean waters on a quest to find a sea route to Asia. At that time the Western Hemisphere in general was unknown to most Europeans, although it had been discovered between the years 800 and 1000 by the vikings. Following the discovery of the islands by Columbus, the area was colonized by several Western cultures. Following the colonization of the Caribbean islands, the Caribbean Sea became a busy area for European-based marine trading and transports, this commerce attracted pirates such as Samuel Bellamy and Blackbeard; as of 2015 the area is home to borders 12 continental countries.
The International Hydrographic Organization defines the limits of the Caribbean Sea as follows: On the North. In the Windward Channel – a line joining Caleta Point and Pearl Point in Haïti. In the Mona Passage – a line joining Cape Engaño and the extreme of Agujereada in Puerto Rico. Eastern limits. From Point San Diego Northward along the meridian thereof to the 100-fathom line, thence Eastward and Southward, in such a manner that all islands and narrow waters of the Lesser Antilles are included in the Caribbean Sea as far as Galera Point. From Galera Point through Trinidad to Galeota Point and thence to Baja Point in Venezuela. Note that, although Barbados is an island on the same continental shelf, it is considered to be in the Atlantic Ocean rather than the Caribbean Sea; the Caribbean Sea is an oceanic sea situated on the Caribbean Plate. The Caribbean Sea is separated from the ocean by several island arcs of various ages; the youngest stretches from the Lesser Antilles to the Virgin Islands to the north east of Trinidad and Tobago off the coast of Venezuela.
This arc was formed by the collision of the South American Plate with the Caribbean Plate and includes active and extinct volcanoes such as Mount Pelee, the Quill on Sint Eustatius in the Caribbean Netherlands and Morne Trois Pitons on Dominica. The larger islands in the northern part of the sea Cuba, Hispaniola and Puerto Rico lie on an older island arc; the geological age of the Caribbean Sea is estimated to be between 160 and 180 million years and was formed by a horizontal fracture that split the supercontinent called Pangea in the Mesozoic Era. It is assumed the proto-caribbean basin existed in the Devonian period. In the early Carboniferous movement of Gondwana to the north and its convergence with the Euramerica basin decreased in size; the next stage of the Caribbean Sea's formation began in the Triassic. Powerful rifting led to the formation of narrow troughs, stretching from modern Newfoundland to the west coast of the Gulf of Mexico which formed siliciclastic sedimentary rocks. In the early Jurassic due to powerful marine transgression, water broke into the present area of the Gulf of Mexico creating a vast shallow pool.
The emergence of deep basins in the Caribbean occurred during the Middle Jurassic rifting. The emergence of these basins marked the beginning of the Atlantic Ocean and contributed to the destruction of Pangaea at the end of the late Jurassic. During the Cretaceous the Caribbean acquired the shape close to that seen today. In the early Paleogene due to Marine regression the Caribbean became separated from the Gulf of Mexico and the Atlantic Ocean by the land of Cuba and Haiti; the Caribbean remained like this for most of the Cenozoic until the Holocene when rising water levels of the oceans restored communication with the Atlantic Ocean. The Caribbean's floor is composed of sub-oceanic sediments of deep red clay in the deep basins and troughs. On continental slopes and ridges calcareous silts are found. Clay minerals having been deposited by the mainland river Orinoco and the Magdalena River. Deposits on th
Macaws are long-tailed colorful New World parrots. Of the many different Psittacidae genera, six are classified as macaws: Ara, Cyanopsitta, Primolius and Diopsittaca; the members of the genus Primolius were placed in Propyrrhura, but the former is correct in accordance with ICZN rules. Macaws are native to Central America and North America, South America, the Caribbean. Most species are associated with forests rainforests, but others prefer woodland or savannah-like habitats. Proportionately larger beaks, long tails, bare, light-coloured, medial areas distinguish macaws from other parrots. Sometimes the facial patch is smaller in some species and limited to a yellow patch around the eyes and a second patch near the base of the beak in the members of the genus Anodorhynchus. A macaw's facial feather pattern is as unique as a fingerprint; the largest macaws are the hyacinth, green-winged macaws. While still large, macaws of the genera Cyanopsitta and Primolius are smaller than the members of Anodorhynchus and Ara.
The smallest member of the family, the red-shouldered macaw, is no larger than some parakeets of the genus Aratinga. Macaws, like other parrots and woodpeckers, are zygodactyl, having their first and fourth toes pointing backward. There are 19 species including extinct and critically endangered species. In addition, there are several hypothetical extinct species that have been proposed based on little evidence. Anodorhynchus Glaucous macaw, Anodorhynchus glaucus Hyacinth macaw, Anodorhynchus hyacinthinus Indigo macaw or Lear's macaw, Anodorhynchus leari Cyanopsitta Little blue macaw or Spix's macaw, Cyanopsitta spixii Ara Blue-and-yellow macaw or blue-and-gold macaw, Ara ararauna Blue-throated macaw, Ara glaucogularis Military macaw, Ara militaris Great green macaw or Buffon's macaw, Ara ambiguus Scarlet macaw or Aracanga, Ara macao Red-and-green macaw, Ara chloropterus Red-fronted macaw, Ara rubrogenys Chestnut-fronted macaw or severe macaw, Ara severa †Cuban red macaw, Ara tricolor †Saint Croix macaw, Ara autochthones Orthopsittaca Red-bellied macaw, Orthopsittaca manilata Primolius Blue-headed macaw, Primolius couloni Blue-winged macaw or Illiger's macaw, Primolius maracana Golden-collared macaw, Primolius auricollis Diopsittaca Red-shouldered macaw or Hahn's macaw, Diopsittaca nobilis Several hypothetical extinct species of macaws have been postulated based on little evidence, they may have been subspecies, or familiar parrots that were imported onto an island and wrongly presumed to have a separate identity.
Martinique macaw, Ara martinica, Rothschild 1905 Lesser Antillean macaw, Ara guadeloupensis, Clark, 1905 Jamaican green-and-yellow macaw, Ara erythrocephala, Rothschild 1905 Jamaican red macaw, Ara gossei, Rothschild 1905 Dominican green-and-yellow macaw, Ara atwoodi, Clark, 1905 The majority of macaws are now endangered in the wild and a few are extinct. The Spix's macaw is now extinct in the wild; the glaucous macaw is probably extinct, with only two reliable records of sightings in the 20th century. The greatest problems threatening the macaw population are the rapid rate of deforestation and illegal trapping for the bird trade. Prehistoric Native Americans in the American Southwest farmed macaws in establishments known as "feather factories". International trade of all macaw species is regulated by the Convention on International Trade in Endangered Species of Wild Flora and Fauna; some species of macaws—the scarlet macaw as an example—are listed in the CITES Appendix I and may not be lawfully traded for commercial purposes.
Other species, such as the red-shouldered macaw, are listed in Appendix II and may be traded commercially provided that certain controls are in place, including a non-detriment finding, establishment of an export quota, issuing of export permits. Sometimes macaws are hybridized for the pet trade. Aviculturists have reported an over-abundance of female blue-and-yellow macaws in captivity, which differs from the general rule with captive macaws and other parrots, where the males are more abundant; this would explain why the blue and gold is the most hybridised macaw, why the hybridising trend took hold among macaws. Common macaw hybrids include miligold macaw and the Catalina. In addition, unusual but healthy intergeneric hybrids between the hyacinth macaw and several of the larger Ara macaws have occasionally been seen in captivity. Macaws eat a variety of foods including seeds, fruits, palm fruits, leaves and stems. Wild species may forage over 100 km for some of the larger species such as Ara araurana and Ara ambigua, in search of seasonally available foods.
Some foods eaten by macaws in certain regions in the wild are said to contain toxic or caustic substances which they are able to digest. It has been suggested that parrots and macaws in the Amazon Basin eat clay from exposed river banks to neutralize these toxins. In the western Amazon hundreds of macaws and other parrots descend to exposed river banks to consume clay on an daily basis – except on rainy days. Donald Brightsmith, the principal investigator of the Tambopata Macaw Project, located at the Tambopata Research Center in Peru, has studied the clay eating behaviour of parrots at clay licks in Peru, he and fellow investigators found that the soils maca