A B C D E F G H I J K L MN O P Q R S T U V W
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ABORIGINESThe earliest known inhabitants of a country.
ALLUVIUMThe fine sand or soil deposited in low places by running water.
ANTIPODEStwo places precisely opposite one another on the earth, such as Barfleur in Normandy and Antipodes Island, south-east of New Zealand. At antipodes the hours and seasons are reversed, so that when it is midnight in summer in Barfleur it is noon in winter on Antipodes.
ARCHIPELAGOA group of islands.
ATOLLA coral reef, typical of the Pacific Ocean, shaped like a ring or horseshoe round a lagoon.
AURORA BOREALISThe Northern lights; an electrical discharge seen by night over the higher latitudes of the northern hemisphere.
AXISThe imaginary line running from pole to pole through the centre of the earth.
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BARA collection of gravel, sand or mud at the mouth of a river.
BASINThe area of land drained by a river and its tributaries.
BAYOUA marshy creek or offshoot to a river or lake which remains swampy because of floods and lack of drainage.
BLOWHOLEA hole in the roof of a seaside cave through which air and sometimes water are forced by the rising tide.
BEACHES, RAISEDLine of former sea shore left dry through a rise in the land.
BORE or EAGREA tidal wave arising in the estuaries of certain rivers.
BUTTEA flat-toped hill, like a MESA but smaller.
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CANYONA narrow, deep gorge, with steep sides, cut by a river through soft rock in a dry region. The biggest and best known is the Grand Canyon of the Colorado River, USA.
CAPEA headland or piece of land jutting out into the sea.
CATARACTA large waterfall, or series of waterfalls.
COLA mountain pass or neck.
CONTINENTAL DRIFTThe movement by which, according to one theory, the continents arrived at their present positions after breaking off from a single original mass of land. The main argument in favour of the theory is that the shores of the continents fit together fairly well, like pieces of a jig-saw puzzle.
CONTOURA line joining places of the same height above sea-level; in a map they help to show the shapes of the land.
CORAL REEFA barrier, lying at or just below the surface of the sea, built up of the skeletons of immense numbers of small creatures called coral polyps.
COULOIRA steep, narrow gorge on the side of a mountain.
CRATERThe funnel-shaped hollow at the top of the cone of a volcano.
CREVASSEA crack in a glacier or ice sheet.
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DATE LINEThe line that follows roughly the 180 degree meridian from Greenwich, and marks the point where according to international agreement the day begins. When a ship crosses this line eastward it goes forward a day; westwards, it goes back a day.
DELTAA fan-shaped tract of flat land at the mouth of a river, made up of silt and other material brought down from up-stream and deposited there. The soil of deltas is usually very rich.
DEWWhat results when at night the ground releases the heat it has stored up during the day, and the air on or just above it becomes cooler. When the temperature falls below a certain point the water vapour on the ground or on nearby objects like blades of grass forms the drops of water we call DEW.
DOLDRUMSThe term for the region of calms and baffling winds near the equator.
DUNESMounds formed by wind-blown sand.
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EARTHQUAKEA movement of the earth, caused either by volcanic activity below the surface or by a large area of earth, weaker than that which surrounds it, slipping a little downwards. Earthquakes need not be severe. In some parts of the Pacific they are a daily, and not especially frightening, occurrence.
EROSIONThe wearing away of the land by sun, wind, rain, frost, running water, moving ice and the sea.
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FAULTA break in the earth's crust along which movement has taken place - usually, but not always, vertically - so that the layers (strata) of the two rock faces no longer match. It is often along a fault that earthquakes occur.
FJORDA long, narrow inlet of the sea, with steep sides, scooped out in ages past by glaciers. A fjord is usually very deep, becoming shallower towards its mouth.
FOHN WINDA warm, dry wind blowing down the sides of mountains facing away from the prevailing wind. It is best known in the valleys of the northern Alps. Other fohn winds are the Chinook (the eastern side of the Rocky Mountains, Canada and the USA); the Nor'Wester(New Zealand) and the Samoon (Iran).
FOGA thick mass of small water drops in the lower air, resulting from condensation. In cities the water drops are often mixed with particles of dust and smoke; when the mixture is really detestable it earns the name SMOG.
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GEYSERSHot springs which shoot jets of hot water and steam into the air at regular or irregular intervals.
GLACIERSMasses of ice that move very slowly down a valley towards the sea, propelled by gravity, carrying rock material with them.
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HAILProduced during a thunderstorm, when moist air is drawn up particularly fast, forming hard pellets of ice in a cumulonimbus cloud. Hailstones grow larger as they pick up more water vapour which freezes around them. Sliced in half they can be seen to be made up of a varying number of coats or skins of ice built outwards from the centre.
HOAR FROSTFrozen DEW.
HORSE LATITUDESRegions of calms and variable winds between latitudes 25 and 40 N and S; so-called because becalmed sailors whose food was running out used to throw their horses overboard.
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ICEBERGSMasses of ice that have broken off from glaciers and are afloat in the sea. Only about one-ninth of an iceberg is above the surface.
INTERNATIONAL DATE LINEGenerally, every country sets its time according to the rising and setting of the sun. So that anywhere in the world the sun is at its highest at about 12 o'clock midday, local time. but suppose you were to travel due west from London so fast that the sun stayed in the same relative position above you (many aeroplanes in fact do this) and that you went right till you came round to London again. According to all the local times you passed through, time would have stood still. Yet in fact your journey would have taken twenty-four hours. By international agreement, a line has been drawn down the meridian opposite that at Greenwich, and where anyone crosses this line East to West he adds on a day; or if from West to East, he takes off a day. The line does not quite keep to the meridian. To avoid confusion it has been drawn round any land or groups of islands where it might have upset the calendar too much.
ISOBARLines on a map joining places of the same average barometric pressure.
ISOTHERMSLines on a map joining places of the same average temperature.
ISTHMUSA narrow strip of land joining two large land areas or joining a peninsula to the mainland. Examples; the isthmuses of Panama and Suez.
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LATITUDEThe distance of a place north or south from the equator, measured in degrees of the MERIDIAN.
LITTORALThe seashore, the land along the coast, or the land lying between the levels of high and low tide.
LONGITUDEThe distance of a place east or west of a given MERIDIAN.
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MAGNETIC NORTHThe pole of the lines of magnetic force that run north and south through the earth. It changes its position slightly from year to year, but in general it is in an area north of Canada, roughly at longitude 07 W and latitude 71 N.
MERIDIANAn imaginary circle on the earth's surface passing through the two poles; on it all places have noon at the same time.
MESAA flat, table-like mass with steep sides all round. Eventually, by wearing away, mesas becomes BUTTES.
METEOROr shooting stars. A body of matter flying around in outer space which enters the earth's atmosphere. It usually travels so fast that the friction caused by passing through the atmosphere burns it up quickly. Some big ones, however, do survive the journey and reach the earth. These are called meteorites. One of the biggest fell in Arizona, blowing a crater a mile wide and 600ft deep.
MIRAGEAn optical illusion, caused by the presence of layers of air of different density, in which the image of a sheet of water may appear over the desert, or images of ships and icebergs, upside-down, over polar waters.
MISTThinner version of FOG.
MONSOONSWinds of the Indian Ocean and nearly lands blowing from the north-east in October to March, and from the south-west in April to September.
MORAINEA continuous line of rocks and gravel along the edges of a glacier.
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OASISAn area in the desert made fertile by the presence of water.
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PAMPASDreary expanses of tree less, grassy plain and salt marshes in Argentina
PENINSULAA tract of land almost surrounded by water.
POTHOLEA hole worn in solid rock, usually at the foot of a waterfall, by the constant grinding of a stone, kept in motion by the current.
PRAIRIEThe almost flat, mostly tree less grass lands of North America. Similar areas are the steppes of the USSR, the pampas of Argentina and the veld of South Africa.
PROJECTIONSWays of representing the earth's surface on a map. Because the earth is round, any map distorts the area it represents (just as flattening out an orange peel distorts its original shape). Only a globe can be really accurate.
Different types of projection have been worked out, each suited to a particular purpose. The two main ones are Conical and Cylindrical. The former shows each hemisphere as a cone which has been unrolled. A Cylindrical Projection shows the earth as though it were an unrolled cylinder. Mercator's projection is cylindrical. Its main fault is that it makes the equator out to be the same length as all other latitudes, even those near the Poles, which are really only a few miles longer. Thus countries near the Poles appear far larger than they really are.
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RAINWhat simply happens when the water droplets that make up a cloud become too heavy to be supported by the upward-moving currents of air.
ROARING FORTIESThe seaman's name for the steady north-west anti-trade winds between latitude 40 and 60m S.
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SIERRAA mountain range.
SIROCCOThe hot, dry and sometimes dusty southerly wind blowing from the Sahara; it is experienced in North Africa, Sicily and southern Italy.
SLEETA mixture of snow and rain that occurs when the snow has been melting during its fall but has not melted completely.
SNOWOccurs when the temperature of the atmosphere at cloud level is below freezing; it falls either as individual ice crystals (always with six sides) or as snowflakes composed of several crystals joined together.
STALACTITEA column of mineral matter, particularly calcium carbonate, hanging from the roof of a cave like a giant icicle.
STALAGMITEA column of calcium carbonate rising from the floor of a cave, formed by water containing the mineral falling from the roof or from a STALACTITE.
STRAITA narrow band of sea connecting two large sea areas. Example: the Straits of Gibraltar, connecting the Atlantic and the Mediterranean.
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TRADE WINDSRegular steady winds in the tropics, between latitudes 30 N and 30 S blowing to the equator.
TROPICSThe tropic of Cancer (line of latitude 23.5 degrees North) and the Tropic of Capricorn (line of latitude 23.5 degrees South) are, respectively, the northernmost and southernmost lines on which the sun's rays shine vertically.
TSUNAMIThe correct name for what is often wrongly called a tidal wave, namely, a huge sea wave sometimes experienced along the coasts of the ocean (as Japan and Chile in 1960) and caused by earthquakes on the ocean floor.
TYPHOONA violent, destructive whirlwind blowing in the China Seas from August to October.
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WATERSPOUTA tornado occurring at sea; a portion of cloud looking like an upside-down cone reaches down from the base of a thunder-clound to where it meets a cone of spray raised from the sea to form a continous column or spout between sea and clound. In the dyas of sailing-ships waterspouts were known to tear ships to pieces.
WHIRLPOOLA circular eddy in the sea produced by the coming together of two currents, or in a river by the way the channel is formed.
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