AREMBERG, or Arenberg, formerly a German duchy of the Holy Roman Empire in the circle of the Rhine Palatinate, between Jülich and Cologne, and now belonging to the Prussian administrative district of Coblenz. The hamlet of Aremberg is at the foot of a basalt hill 2067 ft. high, on the summit of which are the ruins of the castle which was the original seat of the family of Aremberg.
The lords of Aremberg first appear early in the 12th century, but had died out in the male line by 1279. From the marriage of the heiress Mathilda (1282–1299) with Engelbert II., count of La Marck (d. 1328), sprang two sons. The elder of these, Adolf II, (d. 1347), inherited the countship of La Marck; the second, Engelbert III. (d. 1387), the lordship of Aremberg, which he increased by his marriage with Marie de Looz, heiress of Lumain. The lordship of Aremberg remained in his family till 1547, when it passed, by his marriage with Margaret, sister of the childless Robert III., to John of Barbançon, of the great house of Ligne, who assumed the name and arms of Aremberg, and was created a count of the Empire by Charles V. He was governor of Friesland, and for a while commanded the Spanish and Catholic forces against the “beggars,” falling at the battle of Heiligerlee in 1568. His son Charles (d. 1618) greatly increased the possessions of the house by his marriage with Ann of Croy, heiress of Croy and of Chimay-Aerschot, and in 1576 was made prince of the Empire by Maximilian II. His grandson, Philip Francis, was made duke in 1644 by the emperor Ferdinand III., and was succeeded by his brother Charles Eugene (d. 1681), who married Marie Henriette de Vergy de Cusance, heiress of Perwez (d. 1700). Their son, Duke Philip Charles Francis, was killed in 1691 fighting against the Turks, and was succeeded by Leopold (1754), a distinguished soldier of the War of the Spanish Succession, and patron of Rousseau and Voltaire. His son Charles (d. 1778) was an Austrian field-marshal during the Seven Years’ War, and married Louise Margaret of La Marck-Lumain, heiress of the countship of Schleiden and lordship of Saffenberg. By the peace of Luneville (February 1801), the next duke, Louis Engelbert, lost the greater part of his ancestral domain, but received in compensation Meppen and Recklinghausen. On the establishment of the confederation of the Rhine, his son Prosper Louis (to whom, becoming blind, he had ceded his domains in 1803) became a member (1806), and showed great devotion to the interests of France; but in 1810 he lost his sovereignty, Napoleon incorporating Meppen with France and Recklinghausen with the grand-duchy of Berg, and indemnifying him by a rent of 240,702 francs. In 1815 he received back his possessions, which were mediatized by the congress of Vienna, Recklinghausen falling to Prussia and Meppen to Hanover. On account of the one portion he became a peer of the Westphalian estates, and by the other a member of the upper house in Hanover. George IV. of England (9th May 1826) elevated the duke’s Hanoverian possessions to a dukedom under the title of Aremberg Meppen. His brother Auguste Raymond, Comte de la Marck (1753–1833), became famous during the early stages of the French Revolution for his friendship with Mirabeau (q.v.). Duke Prosper Louis died in 1861, and was succeeded by his son Engelbert (d. 1875), who was followed in his turn by his son Engelbert (b. 1872).
The duke of Aremberg is one of the wealthiest of the great continental nobles. His feudal domain in Germany covers an area of over 1100 sq. m., besides which he has large estates in Belgium and France. The duke has residences in Brussels, where he has a famous collection of pictures, and at the château of Klemenswerth near Meppen.
ARENA (Lat. for “sand”), the central area of an amphitheatre on which the gladiatorial displays took place, its name being derived from the sand with which it was covered. The word is applied sometimes to any level open space on which spectacles take place.
ARENDAL, a seaport of Norway, in Nedenaes amt (county), on the south coast, 46 m. N.E. from Christiansand. Pop. (1900) 11,155. It rises picturesquely above the mouth of the river Nid, with a good harbour protected by an island from the open waters of the Skagerrack. The town itself occupies several islets, and some of the houses are supported above the water on piles. The chief exports are timber (very largely exported to Great Britain), wood-pulp, sealskins and felspar. In 1879 Arendal ranked second (after Christiania) as a ship-owning port; in 1899 it had dropped to the fifth place. In and near the town are factories for wood-pulp, paper, cotton and joinery; and at Fevig, 8 m. north-east, a shipbuilding yard and engineering works. The neighbourhood is remarkable for the number of beautiful and rare minerals found there; one of these, a variety of epidote, was formerly called Arendalite. Louis Philippe stayed here for some time during his exile.
ARENIG GROUP, in geology, the name now applied by British geologists to the lowest stage of the Ordovician System in Britain. The term was first used by Adam Sedgwick in 1847 with reference to the “Arenig Ashes and Porphyries” in the neighbourhood of Arenig Fawr, in Merioneth, North Wales.
The rock-succession in the Arenig district has been recognized by W. G. Fearnsides (“On the Geology of Arenig Fawr and Moel Llanfnant,” Q.J.G.S. vol. lxi., 1905, pp. 608–640, with maps) as follows:—
| Ordovician | Caradoc | Dicranograptus—shales. | |||
| Derfel or Orthis—limestone. | |||||
| Llandeilo Group | Rhyolitic ashes = Upper | ||||
| Massive ashes = Middle | Upper Ashes of Arenig. | ||||
| Acid andesitic ashes = Lower | |||||
| Daerfawr Shales.Zone of Didymograptus Murchisoni. | |||||
| Platy ashes | Lower Ashes of Arenig | ||||
| Great Agglomerate | (Hypersthene Andesites). | ||||
| Arenig Group | Olchfa or Bifidus—shales (Didymograptus bifidus). | ||||
| Filltirgerig or Hirundo Beds | Didymograptus hirundo. | ||||
| Erewnt or Ogygia—limestone | |||||
| Henllan or Calymene—ashes | |||||
| Llyfnant or Extensus—flags | Didymograptus extensus. | ||||
| Basal Grit | |||||
 (unconformity) | |||||
The above succession is divisible into: (1) a lower series of gritty and calcareous sediments, the “Arenig Series,” as it is now understood; (2) a middle series, mainly volcanic, with shales, the “Llandeilo Series”; and (3) the shales and limestones of the Bala or Caradoc Stage. It was to the middle series (2) that Sedgwick first applied the term “Arenig.”
In the typical region and in North Wales generally the Arenig series appears to be unconformable upon the Cambrian rocks; this is not the case in South Wales. The Arenig series is represented in North Wales by the Garth grit and Ty-Obry beds, by the Shelve series of the Corndon district, the Skiddaw slates of the Lake District, the Ballantrae group of Ayrshire, and by the Ribband series of slates and shales in Wicklow and Wexford. It may be mentioned here that the “Llanvirn” Series of H. Hicks was equivalent to the bifidus-shales and the Lower Llandeilo Series.
References.—Adam Sedgwick, Synopsis of the Classification of the British Palaeozoic Rocks (1885); Sir A. Ramsay, “North Wales,” Geol. Survey Memoir, vol. iii.; C. Lapworth, Ann. Mag. Nat, Hist. vol. vi., 1880; G. A. J. Cole and C. V. Jennings, Q.J.G.S. vol. xlv., 1889; C. V. Jennings and G. J. Williams, ibid. vol. xlvii., 1891; Messrs Crosfield and Skeat, ibid. vol. lii., 1896; G. L. Elles, Geol. Mag., 1904; J. E. Marr and T. Roberts, Q.J.G.S., 1885; H. Hicks, ibid. vol. xxxi., 1875. See also Ordovician. (J. A. H.)
AREOI, or Areoiti, a secret society which originated in Tahiti and later extended its influence to other South Pacific islands. To its ranks both sexes were admitted. The society was primarily of a religious character. Members styled themselves descendants of Oro-Tetifa, the Polynesian god, and were divided into seven or more grades, each having its characteristic tattooing. Chiefs were at once qualified for the highest grade, but ordinary members attained promotion only through initiatory rites. The Areois enjoyed great privileges, and were considered as depositaries of knowledge and as mediators between God and man. They were feared, too, as ministers of the taboo and were entitled to pronounce a kind of excommunication for offences against its rules. The chief religious purpose of the society was the worship of the generative powers of nature, and the ritual and ceremonies of initiation were grossly licentious. But the
