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Wednesday, March 24, 2010

geography short notes -1


Africa contains well over a thousand languages some have estimated over two thousands, most of african origin & a few of european origin. africa is the most polyglot continent in the world. it is not rare to find individuals there who fluently speak not only several african languages, but one or two european ones as well. there are four major lanugage families native to africa. they are:

- the afro-asiatic languages are a language family of about 240 languages & 285 million people widespread throughout east africa, north africa, the sahel & southwest asia.

- the nilo-saharan language family consists of more than 100 languages spoken by 30 million people. nilo-saharan languages are mainly soken in chad, ethiopia, kenya, sudan, uganda, northern tanzania.

- the niger-congo language family covers much of sub-saharan africa & is propbably the largest language family in the world in terms of different languages. a substantial number of them are the bantu languages spoken in much of sub-saharan africa.

- the khoisan languages number about 50 & are spoken in southern africa by approximately 1,20,000 people . many of the khoisan languages are endangered. the khoi & san peoples are considered the roiginal inhabitants of this part of africa.

following colonialism nearly all african countries adopted official languages that originated outside the continent, although several countries nowadays also use various languages of native origin (such as swahili) as their official language. in numerous countries , english & french are used for communication in the public sphere including government, commerce, education & media.


the andean range is composed principally of two great ranges, the cordilera oriental & cordillera occidental, often seperated by a deep intermediate depression, in which arise other chains of minor importance, the chief of which is chile's cordillera de la costa. other small chain arise on the sides of the great chains. the cordillera de la costa, starts from the southern extremity of the continent & runs in northerly direction, parallel with the coast, being broken up at its beginning into a number of islands & afterwards forming the western boundary of the great central valley of chile. to the north this coastal continues in small ridges / isollated hills along the pacific ocean as far as venezuela, always leaving the same valley. this andean range extended over 7 countries. some of them known as andean states itself. the name andes comes from the Quechua word anti, means "high crest". another , it is derived from spanish word "anden" means terrace in reference the culitvation terraces used by the Incas & other related peoples. the andes range is the highest mountain range outside asia, with its highest peak, Aconcagua , rising to 6960 mts (22,841 ft) above sea level. the andes cannot match himalayas in height but do so in width & are more than twice as long. 


it is a chain or cluster of islands. the word archipelago literally means "chief sea", from greek arkhon & pelagoes. in antiquity , the archipelago was the proper name for the aegean sea & later shifted to islands. archipelago are usually found in the open sea; less commonly , a large land mass may neighbour them. Scotland has more than 700 islands surrounding the mainland. archipelago are often volcanic, forming along mid-ocean ridges but there are many other processes involved in their construction, including erosion & deposition. the 4 largest modern states that are mainly archipelagos are : japan, philippiness, new zealand, indonesia. the largest archipelago in the world by size is in northern canada situated in the artic ocean.


it is a thin , knife-like , ridge of rock which is typically formed when the two glaciers erode parallel U-shaped valleys. the Arete is a thin ridge of rock that is left seperating the two valleys.can also form when two glaciers cirques erode headwards towards one another, frequently this results in saddle shapped pass called Col. the edge is sharpened by freeze thaw weathering. the word arete is actually French for fishbone.

Few examples of arete are :
- knife-edge on Mount Katandin, maine, USA
- clouds rest, in the Sierra nevada, california
- the Minarets in sierra nevada, california
- the garden wall in glacier national park, wales.
- striking edge in the english lake district
- the catwalk in olympic national park, washington, USA.


it is an island of coral that encircles a lagoon partially or completely. the word atoll is derived from the Dhivehi an Indo-Aryan language spoken on the Maldives islands word atholhu. its first recorded use in english was in 1625. the term was popularized by charles darwin who described atolls as a subset in a special class of islands.


atolls are those as " an annular reef enclosing a lagoon in which there are no promontories other than reefs & islet composed of reef detritus". these are the product of the growth of tropical marine organisms, so these islands are only found in warm tropical waters . volcanic islands located beyond the warm water temperature requirements of reef building organism become sea-mounts as they subside & are eroded away at the surface. islands more polar evolve towards sea-mounts islands more equatorial evolve towards atolls. most of the world's atoll are in PAcific ocean & Indian ocean.


  • saya de masha bank, western indian ocean 35,000 km2 without seperate north bank, submerged ; least depth 7m
  • great chagos bank 12,642 km2 land by area only 4.5 km2
  • reed bank, spratly islands 8860 km2, depth 9m
  • macclesfield bank, south china sea 6448 km2, depth 9.2m
  • north bank 5800 km2, depth <10m
  • caysal bank, bahamas 5226.73 km2
  • landsdocone bank, west of new caledonia 5000 km2, depth 3.7m
  • thilaanunmathi-miladhumadulu atoll, maldives 3850 km2
  • huvadhu atoll, maldives 3152 km2
  • trunk lagoon , chuuk 3130 km2
  • kepulauan sabalana, indonesia 2694 km2
  • ishou reef, coral sea 2529 km2
  • bassa de pedro 2474,33 km2, depth 16.4m
  • ardasier bank, spratly islands 2347 km2
  • kwajalein, marshall islands 2304 km2
  • diamond islets bank, coral sea 2282 km2
  • namonuito atoll, chuuk 2267 km2
  • ari atoll, maldives 2252 km2
  • maro reef, north-western hawaiian islands 1934 km2
  • rangiroa tuamatu islands, 1762 km2
  • kolhumadulu atoll, maldives 1617 mk2
  • north male, maldives 1656 km2
  • ontong java, solomon islands 1010

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