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Antarctic Circle. It attains its greatest breadth, more than 6000 m. between the south points of Africa and Australia, and becomes steadily narrower towards the See also:

north, until it is divided by the Indian See also:

peninsula into two arms, the Arabian See also:

Sea on the west and the See also:

Bay of See also:

Bengal on the See also:

east. Both branches meet the See also:

COAST (from Lat. costa, a rib, side)

coast of See also:

ASIA

Asia almost exactly on the Tropic of See also:

Cancer, but the Arabian Sea communicates with the Red Sea and the See also:

Persian Gulf by the Straits of Bab-el-Mandeb and Ormuz respectively. Both of these, again, extend in a north-See also:

WESTERLY

westerly direction to 30° N. See also:

Murray gives the See also:

TOTAL

total See also:

AREA

area, reckoning to 4o° S. and including the Red Sea and Persian Gulf, as 17,320,550 See also:

ENGLISH

English square See also:

MILES, NELSON APPLETON (1839— )

miles, See also:

EQUIVALENT

equivalent to 13,042,000 See also:

GEOGRAPHICAL

geographical square miles. Karstens gives the area as 48,182,413 square kilometres, or 14,001,000 geographical square miles; of these 10,842,000 square kilometres, or 3,150,000 geographical square miles, about 22% of the whole, See also:

lie north of the See also:

EQUATOR (Late Lat. aequator, from aequare, to make equal)

equator. For the area from 4o° S. to the Antarctic Circle, Murray gives 9,372,600 English square miles, equivalent to 7,057,568 geographical square miles, and Karstens 24,718,000 square kilometres, equivalent to 7,182,474 geographical square miles. The Indian Ocean receives few large See also:

rivers, the See also:

CHIEF (from Fr. chef, head, Lat. caput)

chief being the See also:

ZAMBEZI

Zambezi, the Shat-el-Arab, the See also:

INDUS

Indus, the See also:

GANGES (GANGA)

Ganges, the See also:

BRAHMAPUTRA

Brahmaputra and the Irawadi. Murray estimates the total See also:

LAND

land area draining to the Indian Ocean at 5,050,000 geographical square miles, almost the same as that draining to the Pacific. The See also:

ANNUAL

annual rainfall draining from this area is estimated at 4380 cubic miles. See also:

RELIEF

Relief.—Large portions of the See also:

bed still remain unexplored, but a See also:

FAIR

fair knowledge of its See also:

general See also:

FORM (Lat. forma)

form has been gained from the soundings of H.M.S.

" Challenger," the See also:

German " Gazelle " Expedition, and various See also:

cable See also:

SHIPS

ships, and in 1898 See also:

INFORMATION (from Lat. informare, to give shape or form to, to represent, describe)

information was greatly added to by the German " See also:

VALDIVIA

Valdivia " Expedition. A See also:

ridge, less than 2000 fathoms from the See also:

SURFACE

surface, extends south-eastwards from the Cape. This ridge, on which the Crozet Islands and Kerguelen are situated, is directly connected with the submarine See also:

plateau of the Antarctic. From it the See also:

DEPTH

depth increases north-eastwards, and the greatest depression is found in the See also:

ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle between Australia and the Sunda Islands, where " See also:

Wharton deep," below the 3000-See also:

FATHOM

fathom line, covers an area of nearly 50,000 sq. m. Immediately to the north of Wharton deep is the smaller " Maclear deep," and the See also:

long narrow " See also:

JEFFREYS, GEORGE JEFFREYS, 1ST BARON (1648-1689)

Jeffreys deep " off the south of Australia completes the See also:

list of depressions below 3000 fathoms in the Indian Ocean. The 2000-fathom line approaches See also:

close to the coast except (I) in the Bay of Bengal, which it does not enter; (2) to the south-west of India along a ridge on which are the Laccadive and Maldive Islands; and (3) in the See also:

MOZAMBIQUE [Sao Sebastiao de Mocambique]

Mozambique Channel, and on a See also:

BANK

bank north and east of See also:

MADAGASCAR

Madagascar, on which are the See also:

SEYCHELLES

Seychelles, Mascarene Islands and other See also:

groups. Islands.—Like the Pacific, the Indian Ocean contains more islands in the western than in the eastern See also:

HALF

half. Towards the centre, the Maldive, See also:

CHAGOS

Chagos and Cocos groups are of characteristic See also:

CORAL

coral formation, and coral reefs occur on most parts of the tropical coasts. There are many volcanic islands, as See also:

MAURITIUS

Mauritius, the Crozet Islands, and St See also:

Paul's. The chief See also:

CONTINENTAL

continental islands are Madagascar, See also:

SOKOTRA (also spelt Socotra and formerly Socotora)

Sokotra and See also:

CEYLON

Ceylon. Kerguelen, a desolate and uninhabited See also:

ISLAND (O.E. ieg =isle, +land')

island near the centre of the Indian Ocean at its southern border, is See also:

note-worthy as providing a See also:

BASE

base station for Antarctic exploration. Deposits.—The bottom of the Bay of Bengal, of the See also:

NORTHERN

northern See also:

PART

part of the Arabian Sea, of the Red Sea and the Persian Gulf, and of the narrow coastal strips on the east and west sides of the ocean, are chiefly covered by See also:

BLUE (common in different forms to most European languages)

blue and See also:

green muds.

Off the See also:

AFRICAN

African coasts there are large deposits of Glauconitic sands and muds at depths down to moo fathoms, and on See also:

banks where coral formation occurs there are large deposits of coral muds and sands. In the deeper parts the bed of the ocean is covered on the west and south by See also:

GLOBIGERINA, A

Globigerina See also:

OOZE (O. Eng. wdse, cognate with an obsolete waise, mud; cf. O. Nor. veisa, muddy pool)

ooze except for an elongated patch of red See also:

clay extending most of the distance from Sokotra to the Maldives. The red clay covers a nearly square area in the eastern part of the See also:

basin bounded on two sides by the Sunda Islands and the west coast of Australia, as well as two strips extending east and west from the southern margin of the square along the south of Australia and nearly to Madagascar. In the northern portion of the square, north and east of Wharton deep, the red clay is replaced over a large See also:

TRACT (from Lat. tractare, to treat of a matter, through Provencal tractat and Ital. trattato)

tract by Radiolarian ooze. Temperature.—The mean temperature of the surface See also:

WATER

water is over 8o° F. in all parts north of 13° S., except in the north-west of the Arabian Sea, where it is somewhat See also:

LOWER

lower. South of 13° S. temperature falls uniformly and quickly to the Southern Ocean. Between the depths of See also:

Ioo and boo fathoms temperature is high in the north-west, and in the south centre and south-west, and See also:

low in the north-east, the type of See also:

DISTRIBUTION (Lat. distribuere, to deal out)

distribution remaining substantially the same. At 1500 fathoms temperature has become very See also:

UNIFORM

uniform, ranging between 35° and 370 F., but still exhibiting the same type of distribution, though in a very degenerate form. Salinity.—The saltest surface water is found in (a) the Arabian Sea and (b) along a. belt extending from West Australia to South Africa, the highest salinity in this belt occurring at the Australian end. South of the belt salinity falls quickly as See also:

LATITUDE (Lat. latitudo, latus, broad)

latitude increases, while to the north of it, in the See also:

monsoon region, the surface water is very fresh off the African coast and to the north-east. Little is known with certainty about the distribution of salinity in the depths, the number of trustworthy observations available being still very small. Probably the northern and north-eastern region, within the monsoon area, contains relatively fresh water down to very considerable depths.

Circulation.—North of the equator the surface circulation is under the See also:

CONTROL (Fr. contrdle, older form contre rolle, from Med. Lat. contra-rotulus, a counter roll or copy of a document used to check the original; there is no instance in English of the use of " control " in this, its literal, meaning)

control of the monsoons, and changes with them, the currents consisting chiefly of north-east and south-west drifts in the open sea, and induced streams following the coasts. During the northern summer the south-west monsoon, which is sufficiently strong to bring See also:

NAVIGATION (from Lat. navis, ship, and agere, to move)

navigation practically to a standstill except for powerful steamers, sets up a strong north-easterly See also:

DRIFT (from "drive ")

drift in the Arabian Sea, and the water removed from the east African coast is replaced by the upwelling of See also:

COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold water from below; this is one of the best illustrations of this See also:

ACTION

action extant. Along the line of the equator the Indian See also:

COUNTER

counter-current flows eastwards all the See also:

YEAR

year See also:

ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

round, acting . as See also:

COMPENSATION (from Lat. compensare, to weigh one thing against another)

compensation to the great See also:

EQUATORIAL

Equatorial current flowing westwards between the See also:

PARALLELS

parallels of 7° and 2o° S. The equatorial current, on See also:

MEETING (from " to meet," to come together, assemble, 0. Eng. metals ; cf. Du. moeten, Swed. mota, Goth. gamotjan, &c., derivatives of the Teut. word for a meeting, seen in O. Eng. Wit, moot, an assembly of the people; cf. witanagemot)

meeting the northern extremity of Madagascar, sends a See also:

BRANCH (from the Fr. branche, late Lat. branca, an animal's paw)

branch southwards along the east coast of that island, sometimes called the Mascarene current. When the See also:

main equatorial current reaches-the African coast a See also:

minor stream is sent northwards to the source of the Indian counter-current, but the See also:

DISCHARGE (adapted from the O. Fr. discharge, modern decharge, from a med. Lat. discargare, to unload, dis- and earn care, to load, cf. " charge ")

discharge is chiefly by the Mozambique current, which south of Cape See also:

Corrientes becomes the Agulhas current, one of the most powerful stream currents of the globe. On the west coast of Madagascar and on the banks of the African coast south of 3o° S., reaction currents or " back• drifts " move in the opposite direction along the flanks of the Agulhas current; these back-drifts are of great importance to navigation. On clearing the land south of the Cape the See also:

WATERS, TERRITORIAL

waters of the Agulhas current meet those of the west See also:

wind drift of the Southern Ocean, and mingle with them in such a manner as to produce, by interdigitation, alternate strips of warm and cold water, which are met with at great distances south-west and south of the Cape. Between South Africa and Australia the waters form a part of the great west wind drift. The waters of this drift are, in general, of very low temperature, but it is remarkable that the interdigitation just mentioned continues far to the eastward, at least as far as Kerguelen. This fact is probably due partly to the actual intrusion of warm water from the Mascarene current east of Madagascar, and partly to the circumstance that the different temperatures of the waters are so compensated by their See also:

DIFFERENCES, CALCULUS OF (Theory of Finite Differences)

differences of salinity that they have almost precisely the same specific gravity in situ. The west wind drift sends a stream northwards along the west coast of Australia, the West Australia current, the homologue of the Benguela current in the South Atlantic. The See also:

PRINCIPAL

principal feature in the circulation in the depths of the Indian Ocean is a slow See also:

MOVEMENT

movement of Antarctic water northwards along the bottom to take the See also:

PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place of that removed from the surface by evaporation, and by currents in the lower latitudes.

Little is known beyond the See also:

BARE

bare fact that such movement does take place. (H. N.

End of Article: INDIAN OCEAN

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