Encyclopædia Britannica Australia -

Encyclopedias since 1768

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Arenig Series ... Argos

Arenig Series: the second of six divisions (in ascending order) constituting the Ordovician System, representing all those rocks deposited worldwide during the Arenigian Age (488 to 478 million years ago). The series' name is derived from the Arenig mountains in Gwynedd county ...
arenite: any sedimentary rock that consists of sand-sized particles (0.06-2 millimetres [0.0024-0.08 inch] in diameter), irrespective of composition. More formal nomenclature of such rocks is based on composition, particle size, and mode of origin-e.g., sandstone, arkose, quartzite, graywacke, and subgraywacke.
Arenosol: one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO). Arenosols are sandy-textured soils that lack any significant soil profile development. They exhibit only a partially formed surface horizon (uppermost layer) that is ...
Arensky, Anton: Russian composer known especially for his chamber music and songs.
Areopagus: earliest aristocratic council of ancient Athens. The name was taken from the Areopagus ("Ares' Hill"), a low hill northwest of the Acropolis, which was its meeting place.
Arequipa: capital of Arequipa departamento and region, southern Peru, in the Chili River valley of the Andes Mountains. Arequipa lies at more than 7,550 feet (2,300 metres) above sea level, at the foot of the ...
Arequipa: departamento (formed 1822) and region, southern Peru, bounded to the southwest by the Pacific Ocean. Its arid coastal and montane landscapes are cut intermittently by streams flowing from glaciers in the Andes Mountains. Irrigated ...
Ares: in Greek religion, god of war or, more properly, the spirit of battle. Unlike his Roman counterpart, Mars (q.v.), he was never very popular, and his worship was not extensive in Greece. He represented the distasteful aspects of brutal warfare ...
Aretaeus Of Cappadocia: Greek physician from Cappadocia who practiced in Rome and Alexandria, led a revival of Hippocrates' teachings, and is thought to have ranked second only to the father of medicine himself in the application of keen observation and ethics to the ...
arete: (French: "ridge"), in geology, a sharp-crested serrate ridge separating the heads of opposing valleys (cirques) that formerly were occupied by Alpine glaciers. It has steep sides formed by the collapse of unsupported rock, undercut by continual freezing and thawing (glacial ...
Arethusa: in Greek mythology, a nymph who gave her name to a spring in Elis and to another on the island of Ortygia, near Syracuse.
Aretino, Pietro: Italian poet, prose writer, and dramatist celebrated throughout Europe in his time for his bold and insolent literary attacks on the powerful. His fiery letters and dialogues are of great biographical and topical interest.
Arevaci: a Celtiberian tribe, formed by the mingling of Iberians and migrating Celts in the 6th century BC, who inhabited an area near Numantia and Uxama in what is now Spain. The Celtiberians excelled at horsemanship, fighting, and metalworking. They wore ...
Arevalo Martinez, Rafael: novelist, short-story writer, poet, diplomat, and director of Guatemala's national library for more than 20 years. Though Arevalo Martinez's fame has waned, he is still considered important because of his short stories, one in particular.
Arevalo, Juan Jose: president of Guatemala (1945-1951), who pursued a nationalistic foreign policy while internally encouraging the labour movement and instituting far-reaching social reforms.
Arezzo: city, capital of Arezzo provincia, Toscana (Tuscany) regione of north-central Italy, in a fertile plain near the confluence of the Chiana and Arno rivers southeast of Florence. An important Etruscan city, it was known to the Romans as Arretium and ...
Arfersiorfik Fjord: fjord in western Greenland, extending east from Davis Strait to the inland icecap. It is 95 miles (152 km) long with a maximum width of 15 miles (24 km). Its arms receive several glaciers, including the Nordenskiolds. Niaqornaarsuk, a settlement ...
Arfons, Art: American automotive racer, three-time holder of the world's land-speed record for wheeled vehicles.
arfvedsonite: amphibole mineral, an iron-rich sodium silicate. Lithium and magnesium replace iron in the structure to form eckermannite. Both minerals characteristically occur as dark-green crystals in alkali igneous rocks and their associated pegmatites. For chemical formula and detailed physical properties, see ...
argali: (Ovis ammon), the largest living wild sheep, found in the highlands of eastern Central Asia. It may stand 1.3 m (4 feet) high at the shoulders and weigh more than 140 kg (300 pounds). Large horns, present in the rams, ...
Argall, Sir Samuel: English sailor and adventurer who defended British colonists in North America against the French.
Argand burner: first scientifically constructed oil lamp, patented in 1784 in England by a Swiss, Aime Argand. The first basic change in lamps in thousands of years, it applied a principle that was later adapted to gas burners. The Argand burner consisted ...
Argand diagram: graphic portrayal of complex numbers, those of the form a + bi, in which a and b are real numbers and i is the square root of -1; it was devised by the Swiss mathematician Jean Robert Argand in about ...
Argead Dynasty: ruling house of ancient Macedonia from about 700 to about 311 BC; under their leadership the Macedonian kingdom was created and gradually gained predominance throughout Greece. From about 700 the founder of the dynasty, Perdiccas I, led the people who ...
Argelander, Friedrich Wilhelm August: German astronomer who established the study of variable stars as an independent branch of astronomy and is renowned for his great catalog listing the positions and magnitudes of 324,188 stars. He studied at the University of Konigsberg, Prussia, where he ...
Argens, Jean-Baptiste de Boyer, marquis d': French writer who helped disseminate the skeptical ideas of the Enlightenment by addressing his polemical writings on philosophy, religion, and history to a popular readership. Argens's writings simplified the unorthodox empirical reasoning of such Philosophes as Pierre Bayle, Bernard de ...
Argenson, Rene-Louis de Voyer de Paulmy, marquis d': French minister of foreign affairs under King Louis XV from 1744 to 1747. The son of a lawyer, he received legal training and, from 1720 to 1724, served as intendant (royal agent) in Hainaut. As patron of the Club de ...
Argenta: town, Ferrara province, Emilia-Romagna region, northeastern Italy, on the Fiume (river) Reno, southeast of Ferrara city. It has some fine medieval and Renaissance buildings, including the churches of S. Domenico and S. Francesco, and a notable picture gallery. The town ...
argentaffin cell: one of the round or partly flattened cells occurring in the lining tissue of the digestive tract and containing granules thought to be of secretory function. These epithelial cells, though common throughout the digestive tract, are most concentrated in the ...
Argentan lace: lace made at the French town of Argentan from the 17th century, when Louis XIV's minister Jean-Baptiste Colbert founded the lace industry. Characteristic of this lace is a net background consisting of a large hexagonal mesh, the six sides of ...
Argenteuil: town, Val-d'Oise departement, Ile-de-France region, France. It lies along the north bank of the Seine River, northwest of Paris. The town's name comes from silver (argent) deposits exploited there by the ...
Argentia: village, southeastern Newfoundland, Canada. The village is situated along the west coast of the Avalon Peninsula just to the north of the town of Placentia and overlooks Placentia Bay.
Argentina: country of South America, covering most of the southern portion of the continent. The world's eighth largest country, Argentina occupies an area more extensive than Mexico and the U.S. state of Texas combined. It encompasses immense plains, deserts, tundra, and ...
Argentina, La: dancer who originated the Neoclassical style of Spanish dancing and helped establish the Spanish dance as a theatrical art.
argentine: any fish of the family Argentinidae, small, outwardly smeltlike fishes found in deeper waters of the Atlantic and Pacific oceans. The family is usually placed in the order Salmoniformes. Argentines of the species Argentina silus are silvery fishes about 45 ...
Argentine Basin: submarine basin in the floor of the Atlantic Ocean, lying directly east of Argentina. Its deepest sections, the western and southwestern margins, are called the Argentine Abyssal Plain and reach a maximum depth of 20,381 feet (6,212 m). The basin ...
Argentine Museum of Natural Sciences: national museum (founded 1823) in Buenos Aires. It has zoological, botanical, and geological departments.
argentite: a silver sulfide mineral (Ag₂S) that is the most important ore of silver. It is abundant, with other silver minerals, in the sulfide mineral deposits of Kongsberg, Nor.; Kremnica, Slovakia; Zacatecas, Mex.; and the Comstock Lode, Nev., U.S.
Arges: judet (county), southern Romania. The Transylvanian Alps (Southern Carpathians) and the sub-Carpathians rise above the settlement areas that are found in intermontane valleys. The county is drained eastward by the Arges, Cotmeana, and Teleorman rivers. It was formerly included in ...
Arges River: river, that rises in the South ern Carpathians, on the southern faces of Moldoveanu and Negoiu peaks in the Fagaras Range, southern Romania. The river's principal tributaries from the mountains include the Valsan, Doamnei, and Targului rivers. It flows southward ...
Arghezi, Tudor: Romanian poet, novelist, and essayist whose creation of a new lyric poetry led to his recognition as one of the foremost writers in Romania. He produced his best work in the years before World War I.
Arghun: fourth Mongol Il-Khan (subordinate khan) of Iran (reigned 1284-91). He was the father of the great Mahmud Ghazan (q.v.).
arginine: an amino acid obtainable by hydrolysis of many common proteins but particularly abundant in protamines and histones, proteins associated with nucleic acids. First isolated from animal horn (1895), arginine plays an important role in mammals in the synthesis of urea, ...
Argolis: nomos (department), northeastern Peloponnese, southern Greece. It is a narrow, mountainous peninsula projecting eastward into the Aegean Sea between the Saronic Gulf, (to the northeast) and the Gulf of Argolis (to the southwest). Bordered on the north by Korinthos (Corinth) ...
Argolis, Gulf of: deep inlet of the Mirtoon Sea, a western arm of the Aegean, eastern Peloponnese, Greece; it is separated from the Gulf of Saronikos by the Argolis peninsula. Some 30 miles (50 km) long and 20 miles (30 km) wide, it ...
argon: chemical element, inert gas of Group 0 (noble gases) of the periodic table, terrestrially the most abundant and industrially the most frequently used of the noble gases. Colourless, odourless, and tasteless, argon gas was isolated (1894) from air by the ...
Argonaut: in Greek legend, any of a band of 50 heroes who went with Jason (q.v.) in the ship Argo to fetch the Golden Fleece. Jason's uncle Pelias had usurped the throne of Iolcos in Thessaly, which rightfully belonged to Jason's ...
Argonaut: first submarine to navigate extensively in the open sea, built in 1897 by the American engineer and naval architect Simon Lake. Designed to send out divers rather than to sink ships, the Argonaut was fitted with wheels for travel on ...
Argonne: wooded, hilly region in eastern France that forms a natural barrier between Champagne and Lorraine. The Argonne is about 40 miles long and 10 miles wide (65 by 15 km). The hilly massif rarely exceeds 650 feet (200 m) in ...
Argonne National Laboratory: the first U.S. national research laboratory, located in Argonne, Illinois, some 40 km (25 miles) southwest of Chicago, and operated by the University of Chicago for the U.S. Department of Energy. It was founded in 1946 to conduct basic nuclear ...
Argos: city in the nomos (department) of Argolis, northeastern Peloponnese, Greece. It lies just north of the head of the Gulf of Argolis.