In geography, antipodes are two 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. Research Antipodes
A colony is a settlement formed in one country by the inhabitants of another. Colonies may either be formed in dependence on the mother country or in independence. In the latter case the name of colony is retained only in a historical sense. Properly, perhaps, the term should be limited to a settlement which carries on a direct cultivation of the soil, as in the former British colonies of Canada and Australia in contrast to the former in Hindustan or Malta which were the mere superposition on the natives of a ruling race which took little or no part in the general industry of the country.
The motives which lead to the formation of colonies, and the manner of their formation, are various. Sometimes the ambition of extending territory and the desire of increasing wealth have been the chief impulses in colonization; but colonies became a necessity for the redundant population of European states in the 19th century.
Among ancient nations the principal promoters of colonization were the Phoenicians, the Greeks, and the Romans; the greatest colonizers in modern times have been the English and the Spaniards, next to whom may be reckoned the Portuguese, the Dutch, and the French. The Germans during the 19th century contributed largely to the tide of emigration, particularly in the direction of America;
but did little directly as colonizers.
The Phoenician colonies were partly caused by political dissensions and redundant population, but were chiefly commercial, serving as entrepots and ports of repair for Phoenician commerce along the coasts of Africa and Spain, in the latter of which they numbered, according to Strabo, more than two hundred. But it was in Africa that the most famous arose, Carthage, the greatest colonizing state of the ancient world.
The Greek colonies, which were widely spread in Asia Minor and the islands of the Mediterranean, the coasts of Macedonia and Thrace, in South Italy and Sicily, were commonly independent, and frequently soon surpassed the mother states in power and importance.
The colonies of Rome were chiefly military, and while the empire lasted were all in strict subordination to the central government. As the Roman power declined the remains of them amalgamated with the peoples among whom they were placed, thus forming in countries where they were sufficiently strong what are known as the Latin races, with languages (Spanish, Portuguese, French, and Italian) which are merely modifications of the old Roman tongue.
Before America and the way by sea to the East Indies were discovered, the only colonies belonging to European states were those of the Genoese, Pisans, and Venetians in the Levant and the Black Sea, flourishing establishments on which the mercantile greatness of Italy in those days was largely built.
The Portuguese were the first great colonizers among modern states. In 1419 they discovered Madeira, the Azores, and the Cape Verde Islands; the Congo and the Cape of Good Hope followed; and before the century was out Vasco de Gama had landed at Calicut on the Malabar coast of India. The first Portuguese colonies were garrisons along the coasts where they traded: Mozambique and Sofala on the east coast of Africa, Ormuz and Muscat in the Persian Gulf, Goa and Damao on the west coast of India. Colonies were established in Sri Lanka in 1505, in the Moluccas in 1510. Brazil was discovered in 1499, and this magnificent possession fell to Portugal, and was colonized about 1530. Bad government at home and the subjection of the country to Spain caused the loss of most of the Portuguese colonies.
Soon after the Portuguese the Spaniards commenced the work of colonization. In 1492 Columbus, on board of a Spanish vessel, discovered the island of San Salvador. Haiti, or San Domingo, Porto Rico, Jamaica, and Cuba were soon colonized, and before the middle of the 16th century Mexico, Ecuador, Venezuela, New Granada (Colombia), Peru, and Chili were subdued, and Spain took the first rank amongst the colonizing powers of Europe. But the Spaniards never really attempted to develop the industrial resources of the subject countries. The pursuit of mining for gold or silver occupied the colonists almost exclusively, and the enslaved natives were driven to work themselves to death in the mines. Cities were founded, at first along the coasts, for the sake of commerce and as military posts; afterwards also in the interior, in particular in the vicinity of the mines, as Vera Cruz, Cumana, Porto Bello, Carthagena, Valencia, Caracas; Acapuico and Panama, on the coast of the Pacific; Lima, Goncepcion, and Buenos Aires. The colonial intercourse with Spain was confined to the single port of Seville, afterwards to that of Cadiz, from which two squadrons started annually - the galleons, about twelve in number, for Porto Bello; and the fleet, of fifteen large vessels, for Vera Cruz. When the power of Spain declined, the colonies declared their independence, and thus were formed the republics of Mexico, Venezuela, Colombia, Ecuador, Peru, Bolivia, Chili, etc. Cuba, Porto Rico, and the Philippine Islands passed to the United States in 1898; the Caroline Islands, etc, were sold to Germany in 1899; and by 1900 hardly any colony remained to Spain.
The hate of Philip II, who prohibited Dutch vessels from the port of Lisbon, forced the Dutch to import directly from India or lose the large carrying trade they had acquired. Several companies were soon formed, and in 1602 they were united into one, the Dutch East India Company, with a monopoly of the East Indiatrade and sovereign powers over all conquests and colonies in India. The Dutch now rapidly deprived the Portuguese of nearly all their East Indian territories, settled a colony at the Cape of Good Hope in 1650, established a West India Company, made extensive conquests in Brazil between 1623 and 1660, which were soon lost, and more permanent ones on some of-the smaller West India Islands, as San Eustatia, Curacoa, Saba, etc. The growing power of the British and the loss of Holland's independence during the Napoleonic wars were heavy blows to the colonial power of the nation. But the Dutch still possesed numerous colonies in the East Indies at the start of the 20th century, among which the more important were Java, Sumatra, Dutch Borneo, the Molucca Islands, and part of New Guinea, also several small islands in the West Indies, and Surinam.
No colonizing power of Europe had a career of such uniform prosperity as Great Britain. The English attempts at colonization began nearly at the same time with the Dutch. After many fruitless attempts to find a north-east or north-west passage to the East Indies, English vessels found their way round the Cape of Good Hope to the East Indies in 1591. The East India Company was established in 1600. English commerce with India, however, was not at first important, and they possessed only single factories on the continent up until the beginning of the 18th century. The ruin of the Mogul Empire in India after the death of Aurengzebe in 1707 afforded the opportunity for the growth of British power, as the British and French were compelled to interfere in the contentions of the native princes and governors. The French appeared at first to maintain the superiority; but the British in turn got the upper hand, and the victory of Clive at Plassey in 1756 laid the foundation of an exclusive British sovereignty in India. By the middle of the next century the British territory embraced, with the exception of a few dependent states, nearly the whole of India, and this vast territory was still under the government of the East India Company - a mercantile company, controlled indeed by parliament, but exercising many of the most important functions of an independent sovereignty. On the suppression of the Indian mutiny in 1857-1858 the government of India was transferred to the crown by act of parliament in 1858.
The discoveries of the Cabots, following soon after the voyages of Columbus, gave the English crown a claim to North America, which, though allowed to lie dormant for nearly a century, was never relinquished, and which, in the reign of Elizabeth I, led to colonization on a large scale. Walter Raleigh's settlement on Roanoke Island (North Carolina) in 1585 failed to become permanent, but in 1607 the colonists sent out by the London Company to Chesapeake Bay founded Jamestown, on the James River, in Virginia. The next great settlement was that of the Pilgrim Fathers, who landed on the 21st of December 1620, in Massachusetts Bay. The colonization of New Hampshire, Maine, New Jersey, Connecticut and Rhode Island, soon followed. In the State of New York and the Hudson River Territory the British found the Dutch already in possession; but in 1664 they seized the colony of New Amsterdam by force, changing its name to New York in honour of James, Duke of York. Pennsylvania was founded by William Penn, and colonized with Quakers in 1682; Maryland in 1631 by a party from Virginia; Carolina in 1670 and Georgia in 1732 by colonies from England.
Colonies were early established in the West India Islands, including Barbados, half of St. Christopher's in 1625, and soon after many smaller islands. Newfoundland was taken possession of in 1583, colonized in 1621 and 1633. Canada was surrendered to Britain at the Peace of Paris in 1763. In 1764 began the disputes between Britain and its North American colonies, which terminated with the acknowledgment of the independence of the United States, Canada remaining a British dependency.
Australia was discovered in the beginning of the 17th century. The first Australasian settlements of Britain were penal colonies. New South Wales, discovered in 1770, was established as a penal colony in 1788; Tasmania (Van Diemen's Land), discovered by Tasman in 1642, followed in 1803; West Australia, also first used as a penal settlement, became a free colony in 1829; Victoria was colonized in 1835, and made an independent colony in 1851; South Australia was settled in 1836. In 1851 the discovery of gold in Victoria gave a great impetus to the Australian Colonies. Queensland was made a separate colony from N.ew South Wales in 1859. New Zealand, discovered by Tasman in 1642, began to be used for whale-fishery about 1790, was settled in 1839, and made a colony in 1840. In 1874 the Fiji Islands, and in 1884 part of New Guinea, were annexed as crown colonies. In South AfricaCape Colony, first settled by the Dutch in 1652, finally became a British colony in 1815. Natal followed in 1843. Later annexations were Bechuanaland in 1885, Zululand in 1887, Rhodesia (now Zimbabwe) in 1888-89, and the Orange River Colony and Transvaal in 1900. In Western Africa were the colonies of the Gold Coast, Gambia, and SierraLeone - ancient possessions of the British crown; with Lagos and Nigeria acquired in 1885 and after. Other possessions were British East Africa (Kenya), with Uganda and Somaliland. Gibraltar was acquired in 1704, Malta in 1800.
According to their government relations with the crown the colonies were arranged under three heads: (1.) Crown colonies, in which the crown had the entire control of legislation, while the administration was carried on by public officers under the control of the home government. (2.) Colonies possessing representative institutions but not responsible government, in which the crown had no more than a veto on legislation, but the home government retained the control of public officers. (3.) Colonies possessing representative institutions and responsible government, in which the crown had only a veto on legislation, and the home government had no control over any officer except the governor. All colonies were, however, disabled from such acts of independent sovereignty as the initiative in war, alliances, and diplomacy generally.
France was somewhat late in establishing colonies. Between 1627 and 1636 the West Indian islands of St Christopher's, Guadeloupe, and Martinique were colonized by private persons. Champlain was the pioneer of the French in the exploration of the North American continent, and founded Quebec in 1608. Colbert purchased several West India islands, as Martinique, Guadeloupe, St Lucia, etc, and sent out colonists in 1664 to Cayenne. In 1670 the East India Company formed by Colbert founded Pondicherry, which became the capital of extensive possessions in the East Indies. At the beginning of the 18th century France had extensive settlements in Canada, Nova Scotia, and Newfoundland, the most flourishing of the West India islands, and she seemed to have a prosperous career before her in India. Ere long, however, the rival interests of British and French colonists brought about a conflict which terminated in the loss of Canada and other North American possessions, as well as many of the West India Islands, while the dominion of India passed into the hands of the British.
During the 19th century Germany made an effort to take rank as a colonial power, and acquired in Africa the territories of Damaraland, Great Nama Land, etc, on the south-west coast, north of Cape Colony; the Cameroons District; a large portion of territory formerly claimed by the Sultan of Zanzibar, extending inland to Victoria Nyanza, etc; also in the Pacific a portion of New Guinea, then subsequently called Kaiser Wilhelm's Land, the BismarckArchipelago, Marshall Islands, etc.
The ISO (International Standards Organisation) assigns a two character code to each country name. These codes are used by Internet 'whois' databases (these two character abbreviations are the whois country codes) and also other applications.
A day is either the interval of time during which the sun is continuously above the horizon, or the time occupied by a revolution of the earth on its axis, embracing this interval (the period of light) as well as the interval of darkness. The day in the latter sense may be measured in more than one way. If we measure it by the apparent movement of the stars, caused by the rotation of the earth on its axis, we must call day the period between the time when a star is on the meridian and when it again returns to the meridian: this is a sidereal day. It is uniformly equal to 23 hours, 56 minutes, 4.098 seconds. But more important than this is the solar day, or the interval between two passages of the sun across the meridian of any place. The latter is about 4 minutes longer than the former, owing to the revolution of the earth round the sun, and it is not of uniform length, owing to the varying speed at which the earth moves in its orbit and to the obliquity of the ecliptic. For convenience an average of the solar day is taken, and this gives us the mean solar or civil day of 24 hours, the difference between which the actual solar day at any time is the equation of time.
The length of the days and nights at any place varies with the latitude and season of the year, owing to the inclination of the earth's axis. In the first place, the days and nights are equal (twelve hours each) all over the world on the 21st of March and the 21st of September, which dates are called the vernal (spring) and autumnal equinoxes. Again, the days and nights are always of equal length at the equator, which, for this reason, is sometimes called the equinoctial line. With these exceptions, we find the difference between the duration of the day and the night varying more and more as we recede from the equator, and at the poles the year consists of one day of six months' duration, and one night of the same.
The Babylonians began the day at sun-rising; theJews at sun-setting; the Egyptians and Romans at midnight, as do most modern peoples. The civil day in most countries is divided into two portions of twelve hours each. The abbreviations PM. and AM. (the first signifying post meridiem, Latin for afternoon; the latter ante meridiem, forenoon) are requisite, in consequence of this division of the day. The Italians in some places reckon the day from sunset to sunset, and enumerate the hours up to twenty-four; the Chinese divide it into twelve parts of two hours each.
For astronomical purposes the day is divided into twenty-four hours instead of two parts of twelve hours. Formerly it began at noon, but since the 1st of January 1885, the day of twenty-four hours begins at midnight at Greenwich Observatory; and this reckoning is now generally adopted for astronomical purposes elsewhere than at Greenwich. The Greenwich day practically determines the date for all the world. At mid-day at Greenwich the date (day of the week and month) is everywhere the same, though there are all possible differences in naming the hour of the day. But mid-day at Greenwich is the only instant at which we ever have the same date all over the world. The meridian of midnight, which is then at 180 degrees east or west, goes on revolving, gradually bringing a new date to every place to the west of that line, but obviously not bringing that new date to the places immediately to the east of that line until twenty-four hours after. From this it follows that whereas places on the one side of the globe never have a different date except when midnight lies between them, places on the opposite side of the globe, and on different sides of the meridian of 180 degrees east Or west never have the same date except when midnight lies between them. The actual difference of time between Wellington in New Zealand and Honolulu in Hawaii is only about two hours; yet a person at Wellington may date a letter 9 o'clock AM 26th June, while another writing at the same instant at Honolulu dates his 11 o'clock AM 25th June.
A Fohn wind is a 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). Research Fohn Wind
In geography, a geyser (from the Icelandic geysir which in turn deribes from heysa meaning to gush or rush forth) is a term applied to natural springs of hot water of the kind that were first observed in Iceland. The geysers of Iceland, about a hundred in number, lie about 30 miles north west of Mount Hecia, in a plain covered by hot-springs and steaming apertures. The two most remarkable are the Great Geyser and the New Geyser or Strokkur (churn), the former of which throws up at times a column of hot water to the height of from 80 to 200 feet. The basin of the Great Geyser is about 70 feet across at its greatest diameter. The New Geyser, which is only 100 meters away, is much smaller in size. The springs are supposed to be connected with Mount Hecia, and the phenomenon of eruption has been explained by Tyndall as due to the heating of the walls of a fissure, whereby the water is slowly raised to the boiling point under pressure, and explodes into steam, an interval being required for the process to be repeated. The geysers of Iceland, however, were surpassed by those discovered in the Rocky Mountains in the Yellowstone Region of Wyoming Territory, the largest of which throw up jets of water from 90 to 250 feet high. The hot-lake district of Auckland, New Zealand, is also famous in possessing some of the most remarkable geyser scenery in the world. These phenomena are of three kinds: the puias (fire-springs), geysers continually or intermittently active; ngawhas or inactive puias, which emitsteam, but do not throw up columns of water; and waiariki or hot-water cisterns. This region is remarkable for the number of natural terraces containing hot-water pools or cisterns, and its lakes all filled at intervals by the boiling geysers and thermal springs, but the configuration of the country was considerably altered by the disastrous volcanic outbreak of 1886. Ngahapu or Ohopia, a circular rocky basin, 40 feet in diameter, in which a violent geyser is constantly ng up to the height of 10 or 12 feet, emitting dense clouds of steam, is one of the natural wonders of the southern hemisphere. Research Geyser
Glaciers are icy masses of great bulk, harder than snow, yet not exactly like common ice, which cover the summits and sides of mountains above the snow-line. They are found in Switzerland, Scandinavia, the Andes, etc.
They extend down into the valleys often far below the snow-line, and bear a considerable resemblance to a frozen torrent. They take their origin in the higher valleys, where they are formed by the congelation and compression of masses of snow in that condition called by French writers neve, by German authors, firn.
The ice of glaciers differs from that produced by the freezing of still water, and is composed of thin layers filled with air-bubbles. It is likewise more brittle and less transparent. The glaciers are continually moving downwards, and not unfrequently reach the borders of cultivation. The rate at which a glacier moves generally varies from 45 to 60 cm in twenty-four hours.
At its lower end it is generally very steep and inaccessible. In its middle course it resembles a frozen stream
with an undulating surface, broken up by fissures or crevasses. As it descends it experiences a gradualdiminution from the action of the sun and rain, and from the heat of the earth. Hence a phenomenon universally attendant on glaciers - the issue of a stream of ice-cold turbid water from their lower extremity. The descent of glaciers is shown by changes in the position of masses of rock at their sides and on their surface. A remarkable glacier phenomenon is that of moraines, as they are called, consisting of accumulations of stones and detritus piled up on the sides of the glacier, or scattered along the surface. They are composed of fragments of rock detached by the action of frost and other causes.
The fissures or crevasses by which glaciers are traversed are sometimes more than 30 meters in depth, and from being often covered with snow are exceedingly dangerous to travellers. One of the most famous glaciers of the Alps is the Mer de Glace, belonging to Mont Blanc, in the valley of Chamouni, about 1740 meters above sea level. It is more especially, however, in the chain of Monte Rosa that the phenomena of glaciers are exhibited in their greatest sublimity, as also in their most interesting phases from a scientific point of view.
Glaciers exist in all zones in which mountains rise above the snow-line. Those of Norway are well known, and they abound in Iceland and Spitzbergen. Hooker and other travellers gave accounts of those of the Himalaya. They are conspicuous on the Andes, while the Southern Alps of New Zealandrival in this respect the Alpine regions of Switzerland.
The problem of the descent of the glaciers is of extraordinary interest, and various theories have been put forward to account for it. It was shown by Professor Forbes, of Edinburgh, that a glacier moves very much like a river; the middle and upper parts faster than the sides and the bottom; and he showed that glacier motion was analogous to the way in which a mass of thick mortar or a quantity of pitch flows down in an inclined trough. His theory is known as the viscous theory of glaciers, which presupposes that ice is a plastic body, and this plasticity has been satisfactorily explained by Professor James Thomson of Glasgow by the phenomenon of the melting and refreezing of ice.
Water, he discovered, when subjected to pressure, freezes at a lower temperature than when the pressure is removed. Consequently when ice is subjected to pressure it melts; if it is relieved of pressure the water again solidifies. Therefore if two pieces of ice are pressed together, they tend to relieve themselves by melting at their points of contact, and the water thus produced immediately solidifies on its escape. If ice is strained in any way it similarly relieves itself at the strained parts, and a similar regelation follows. This, when applied to the glaciers, gives a complete explanation of their plasticity. Pressed downwards by the vast superincumbent mass, the ice gradually yields. Melting and re-freezing takes place at some parts, at others the gradual yielding at strained points goes on. In the latter process there is no visible melting, but there is the gradual yielding from point to point to the pressure above, and there is the transference relatively to each other of the molecules that constitute the, at first sight, solid mass. If, however, at certain points the strain is intense, the ice becomes extremely brittle. The latter fact disposes of Tyndall's objection to Forbes' theory, which was based on the fact that crevasses proved the brittleness, and not the viscosity of ice. Research Glacier
Lakes are accumulations of water in hollows on the earth's surface. When they are drained by rivers their waters are fresh, but when they have no outlet they are salty, e.g. the Dead Sea, Sea of Aral, etc.
Lakes may owe their origin to:
Barriers across a river valley hold back the water, which forms a lake. Such barriers may be of various types. (a) Sometimes artificial barriers of concrete and masonry are built across a valley so as to make a lake which can act as a reservoir for the water-supply of a large city, e.g. LakeVyrnwy for Liverpool. (b) A glacier may deposit a mass of morainic material across a valley. In this way the lakes of the Lake District and many of the Scottish lakes were formed. (c) A landslip may occur. A lake was formed thus in the Upper GangesValley in 1892. Two years later the landslip dam gave way, and disastrous floods occurred downstream. (d) Oxbow lakes are formed from the meanders of rivers. The deposition of silt at the two ends of the 'oxbow' closes the channel between the main river and its old loop. Many oxbow lakes border the River Murray in Australia, and the lower Mississippi. (e) Sometimes a lavastream may flow across a valley and cause the formation of a lake, e.g. LakeTaupo in New Zealand. (f) Sometimes large estuaries are partially filled with silt. In the portions not so filled are large shallow lagoons. Such lagoons are found in deltaic areas. The NorfolkBroads are portions of an old river estuary. (g) When a silt-laden stream enters a lake its speed is checked and a barrier or delta is built across the lake splitting it into two portions. This has happened in the Lake District, where Keswick stands in the alluvial flats between Lakes Bassenthwaite and Derwentwater, and in Switzerland, where Interlaken is situated in the flats between Lakes Thun and Brienz. (h) The action of the sea often causes an accumulation of sand and pebbles which cuts off a lagoon of sea water. The Fleet in Dorset is such a lagoon, cut off from the sea by Chesil Bank, a long pebble beach which joins Portland Island to the mainland.
The nehrungs of East Prussia are sand-spits which enclose the shallow salt-water lagoons or halls, such as Kurische Haff. Earth movements cause lakeformation when subsidence occurs. This is most easily seen in rift valleys. Examples of riftvalley lakes are the Dead Sea, Lakes Nyasa and Tanganyika in Africa, and LakeTorrens in Australia. These are all long, narrow, and very deep lakes.
In Cheshire, the removal of underground beds of salt has caused subsidence resulting in the 'meres' of the Weaver Valley. The 'folding' of the earth across the line of a river valley may partially block a river and help to form a lake. The study of a good physical map will reveal the connection between mountain building and the formation of LakeGeneva and LakeConstance in Switzerland. Where there are large areas of depressed lowland wide and shallow lakes are formed in the lowest part of the depression, for example the Sea of Aral in Asiatic Russia, LakeBalaton in Hungary, and LakeEyre in Australia. Ice sheets and valley glaciers may scoop out hollows to form 'rock basins'. Mountain tarns and corrie lakes in North Wales and Scotland have been formed in this way. Water also accumulates in the hollows of unevenly- distributed glacial drift. Such are the lakes of East Prussia, and also those of the Cheshire-Shropshire borders near Ellesmere. Subsidence of the land surface and consequent lakeformation may be directly related to volcanic action. Lough Neagh in Northern Ireland is a shallow lake formed by subsidence of this type. Lakes are often formed by the accumulation of water in the craters of extinct volcanoes, for example the Laachersee in the Eifel region of Germany. Research Lakes
Mountains are often classified according to their mode of formation: Fold
mountains; Block mountains; Residual mountains; Volcanic mountains.
High mountain chains such as the Himalayas, Andes, Alps, and Rockies are known as new fold mountain systems. The term 'fold' is a reference to the way in which such mountains have been formed. Throughout millions of years slow movements of the earth's crust have caused these
mountains to be raised. The movements which have resulted in mountain buildings were not, however, vertical uplifts. They were primarily horizontal movements, the effect of which was to cause the crust of the earth to 'wrinkle', in a similar way to which a tablecloth wrinkles if it is pushed along the table. The arched or upraised parts of the folds are known as anticlines and the troughs as synclines. These folds can vary greatly in size. Mountain building is undoubtedly due to some deep-seated cause. For a long period the most simple explanation was that folding was entirely due to the cooling and contraction of the earth, so that the crust, already cold and shrunken, had to wrinkle to fit itself to the still cooling and contracting 'core'. One of the objections advanced against this theory is that the amount of shrinking necessary to account for the Himalayas, Alps, etc., seems to be greater than the mere contraction of the earth would allow. While the theory of contraction cannot be completely rejected, serious consideration must be given to the more recent explanations of mountain building. For instance, Wegener suggests that mountain building may be due to the 'wrinkles' produced by the drifting of a continental mass, e.g. that the Alps were formed by the northward drift of the African continent towards the more stable blocks of Central Europe. As the African mass drifted slowly northward the zone between it and the European mass became narrower, and the land was raised into high ridges or folds. The raising of the Alps was accompanied by the formation of the deep trough which contains the Mediterranean Sea. The same hypothesis would account for the building of the Himalayas and the depression of the Indo-Gangetic trough by the northward drift of the Deccan mass.
During the physical history of the earth, mountain building appears to have proceeded more actively at some periods than others. Fold mountains are, therefore, not all of the same age. The newest group of fold mountains include the Himalayas, Alps, Rockies, and Andes. During an earlier period of folding (the Carboniferous) the Pennines, Appalachians, the Cape Ranges of South Africa, and the Dividing Range of Australia were uplifted. A still earlier period of folding accounted for the original mountains of Scotland and Norway, of which the present mountains are merely the worn down stumps. The older fold mountains, which have been subjected to the forces of denudation (such as the weather, rivers, glaciers, etc.) for long geological periods, are much lower and less rugged than the newer fold mountains. The term 'new fold' is applied to the mountain ranges which have been folded most recently, but they seem very old when their age in actual years is considered because they were uplifted many millions of years before historic time. Mountain building is a very long and slow process; and in the case of certain mountain chains, such as the Andes and the mountains of Japan, is probably still proceeding.
The new fold mountain systems of the world, except in such instances as the simple low folds of the Weald (South-east England), usually consist of high parallel ranges, the average height being well over 3000 metres. In the Himalayas' the highest peak rises to 8840 metres; in the Andes 7000 metres; in the Rockies 6000 metres; in the Alps to 4600 metres. Vast though these heights appear, the wrinkles of the earth's crust are only slight. The highest mountain in the world (MountEverest) is about five miles high, so that on a globe of 40 cm, diameter it would protrude only 2.5 mm. Most of the active volcanoes are found in the neighbourhood of fold mountains, where the crust of the earth has been fractured during the process of folding. All around the PacificOcean there are many active and extinct volcanoes, as in New Zealand, the East Indies, Japan, and North, Central, and South America. Another belt of active volcanoes is associated with the fold mountains of the West Indies. The mountains of this type are characterised by ruggedness of relief in contrast to the smooth and rounded contours of mountain areas which have been subjected to weathering agents for long periods of time. This is obvious if pictures of the Alps and the Scottish Highlands are compared.
Mountains are effective climatic barriers, and the climates of regions on either side of a high mountain range are very different. For example, the coast lands of British Columbia have an equable climate and a heavy rainfall, while the lands to the east of the Rockies have an extreme climate and light rainfall. Again, the climate of the mountainous areas differs from that of the adjacent lowlands. The great mountain systems of the world are mainly important for their minerals, and, in the temperate zone, for their lumber. In the plateau regions of some mountain systems agriculture has been made possible by irrigation, and above the forests in temperate areas there are valuable alpine pastures. The swift streams of mountains are frequently sources of hydro-electric power, especially in countries which have no coal, such as Switzerland and Norway. In North America, the Western Cordillera provides gold, copper, lead, and silver, especially in the states of Nevada and Montana. The Andes provide tin and copper (Bolivia), gold and platinum
(Colombia), and silver (Peru). The Highlands of East Australia are important for copper and gold. The lumbering industry is specially important in British Columbia, Washington, and Oregon (soft woods), the Central American mountainous lands (hard woods), the Himalayan slopes (teak and sal), and the Scandinavian mountains (soft woods).
To provide food for the mining communities in inaccessible mountain areas, agriculture has been developed. There are numerous irrigation schemes in operation in most of the mountain states of the USA, e.g. at SaltLake City in Utah. Similarly, the Andean states, e.g. Bolivia, grow small quantities of cereals in the plateau areas. Mountain pastures have been utilised most extensively for cattle rearing in Switzerland and Scandinavia. The vast central plateau of Asia is, owing to difficulty of access and climatic extremes, so isolated from other regions that very little development of any kind, on modern lines, has taken place. High mountain ranges are also barriers to communication, and so tend to separate peoples. Traffic across mountains is limited to the passes, which are often so high as to be snowbound in winter. Such ranges as the Alps, Andes, etc. can only be crossed with great difficulty or by expensive tunnelling.
It sometimes happens that movement of the earth's crust occurs along cracks or faults. Where such movement leaves a block of higher land standing between two areas of lower land, the highland is known as a 'Block Mountain' or horst. The Vosges and Black Forest Mountains are examples of such formations These mountains are usually very steep-sided, and often the summit levels are roughly the same.
When an area of highland remains standing above the general level after rivers and other natural agents have lowered the surface of the surrounding area, the name residual mountain is used. Sometimes such highlands are called 'mountains of denudation'. This term can usually be applied to the mountain ridges associated with 'dissected plateaux'. Included in this class are the mountain ridges of the Highlands of Scotland, the Sierras of Central Spain, and the Mesas and Buttes of the western plateaulands of the United States.
Mountains may be formed by volcanic material piled up around a crater, such mountains are popularly known as volcanoes. Research Mountains
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Antipodes
