2 0 0

sk{I-t«-dn-tbäv Akn-Ìâ v ]co-£-bnÂF{Xm-as dm¦mWv \n§Ä e£yw ImWp-¶Xv?

CsX´p tNmZyw! sabn³ ]co£ \S-¡m³ t]mIpt¶ DÅq. Fs ms¡ tNmZy-§Ä hcp-sa¶v Hcp [mc-W-bp-an-Ã. am{X-hp-aà AhnsS ChnsS Ipsd Imcy-§Ä t\m¡n-bn-«p-­v. F¶-ÃmsX Hcp thorough prepa-ration \S m-\pÅ kml-Ncyw CXp-hscD­m-bn-«n-Ã. C\n AXn\v Ign-bp-sa¶v tXm¶p-¶p-an-Ã. am{X-hp-aà Cu dm¦v b-en-eqsSIt®m-Sn- - tXmsS DÅ confidence \jvS-s -«p. Npcp-§nb kabw sIm­v C{Xsbs¡]Tn- s - Sp-¡m³ km[n-¡ptam? C\n Fgp v]co-£-bn F§n-s\-sb-¦nepw Ic-I-bdnF¶n-cn-¡-s«, ]ns¶ CâÀhyq Fs¶mcp IS-¼-bnsÃ? AXn\v F{X-t]-cpsS Imep-]n-Sn-¡-W-sa-¶mÀ¡-dn-bmw. ]ns¶ F§s\ e£ywImWp¶ dm¦v GsX¶v ]dbpw?

adp-]Sn Rm³ {]Xo-£n- Xv Xs¶. Cu]co-£bv¡v X¿m-sd-Sp-¡p¶ 99% DtZym-KmÀ°n-Ifpw \ÂIm-\n-S-bpÅ D¯camWnXv. CXn \n¶pw Hcp Imcyw \n§Ät_m[y-s -«n-cn-¡pw. sk{I-t«-dn-tbäv ]co-£bv¡v X¿m-sd-Sp-¡p¶ tIc-f- nse qcn-mKw DtZym-KmÀ°n-Isf _m[n- n-cn-¡p-¶Xv

]cm-Pb Pzc-am-Wv. kz w Ign-hnepw Icp- n-

epw, hn -h-ti-jn-bnepw hniz-kn-¡m-sX, ]co-£-bpsS AhyàX-bn-epw, ImTn-\y- nepwkzbw \jvS-s¸«v, CâÀhyqs\ kwi-b-t msS ho£n v, kz w km[y-X-IfpsSISbv¡v I n hbv¡p-I.

kplrs , e£yw hnP-b-am-sW-¦nÂBZyw th­Xv kz w Ign-hn hniz-kn-¡pIF¶-Xm-Wv. IqSp-X ]Tn-¡p-¶-Xn\v ap¼vCXp-hsc \n§Ä t\Snb Adnhv Xncn- -dn-b-em-Wv. \n§Ä BZy-ambn kvIqfn t]mbn]Tn v XpS-§nb Imew apX C¶v hsckzcq-]n Adn-hpw, B Adn-hn \n¶pwDÄ n- cnªv h¶ Ah- t_m-[hpw, \n§-fpsSkmam\y _p²nbpw tNÀ¶-XmWv \n§-fpsSreservoir of resource AYhm hn -h-ti-jn-bpsS AW-s¡-«v. CXns\ Xncn- -dn-bp-I,DWÀ p-I, t_m[-]qÀÆw ]co-£-bnÂ{]-tbm-Kn-¡pI. hnP-bn-¡m-\pÅ Adn-hnsâFXm­v 50% Ct mÄ Xs¶ \n§-fn-ep­vF¶-XmWv ]c-amÀ°w. AXv ]e-cnepw crudecq]-¯n Bbn-cn-¡pw Fs¶-bpÅp.AXns\ refine sNbvXv revitalise sNbvXvready B¡n {]tbm-Kn-¡m-\pÅ Hcp mis-sile B¡n amä-emWv Hcp ]cn-[n-hsc X¿m-sd-Sp- v. tIcf Ncn- {X- nse Wagon Trag-edy F¶ kw hw hmbn- m AXn 80%\n§Ä¡v Adn-bm-hp¶ hkvXp-X-bm-sW¶v

Xncn- - dn-bmw. At mÄ CXmWv ]co£ tNmZy-sa-¦n D¯cw Fgp-Xm³ 80% \n§-fpsSresource Dw 20% X¿m-sd-Sp¸pw am{Xw aXn-bm-Ipw. qcn- mKw ]co-£m-tNm-Zy-§fpw C -c- n Df-f-hbm-bn-cn-¡pw. What is solarsystem F¶ tNmZy- n\v D cw 90% \n§-fpsS resource Dw 10% X¿m-sd-Sp pw am{XwaXn-bm-Ipw. So the most important thingis to build up faith in your ability andknowledge. Don't under estimate yourknowledge and resource. Recogniseyour true ability and appreciate it. Itcan work wonders. Take a strong re-solve to make eye of your potential inan optimum level.Hcn-¡epw \n§-fpsSNn Cu ]d-bp-¶-X-e- n-tebv¡v hgn-sX-ä-cp-Xv. I don't know anything. I am poor.My fate is uncertain. I cannot performwell. My memory is poor. I have for-gotten everything that I learnt in mylife. My General Knowledge is verypoor. My English is hopeless. MyMalayalam is horrible.

Cu ]d-bp¶ Xe- n-epÅ hyàn-bm-bn-cp¶p \n§Ä F¶p-s­-¦n 5þmwÌm³tUÀUvt]mepw hnP-bn-¡m³ km[n-¡p-am-bn-cp-¶n-Ã. The fact that you are a de-gree holder shows that you are capable,competent and able.

\n§-fpsS Nn -bn sXfn-ªp-h-tc­bmYmÀ°yw CXm-Wv.

This is my opportunity. If I make useof my talent, ability and knowledge, Ican get this job. I need a job. This jobseems to me the best possible job. I amnot a bad candidate. In fact I think thatI am capable. Passing the prelims showsmy ability. In my life, I have collecteda lot of valuable information in varioussubjects. I am sure that this informationwill help me to frame apt answers tovarious questions. I am going to use mytime in two ways. First of all I mustmake use of my knowledge effectively.Secondly, I have to learn new informa-tion which is needed for securing a toprank in the exam. I have full faith in myability. I am willing to work hard formy success. I firmly believe that if Iwork sincerly and devotedly I can getone of the top ranks in the exam. NowI am determined. I must get this job atany cost.

Geography

2 0 1

Fill in the Blanks1. The temperature at which the

air is fully saturated is called.............

2. The type of soil typicallyformed under tropical mon-soon condition is .............

3. The bottom of a river is called.............

4. The waves which passthrough the core of the earthis .............

5. Ocean covers ............. part ofthe earth’s surface

6. A vent in the ground of avolcanic area which gives offvolcanic hot gases is knownas .............

7. The narrow contact zone ofland, water and air whichcontains all forms of life iscalled .............

8. Maps showing differentcountries and states of theworld with their boundariesare called .............

9. Virunga National Park inCongo is famous for .............

10. ............. is the largest island inthe world.

11. The Trans-Siberian Railway(8960 km) connects ......... inthe west to .......... in the east.

12. Humbolt ocean current is in............. ocean.

13. The leeward side of amountain which does notreceive rain is known as the.............

14. The study of fossils is .............15. ............. is the propounder of

the continental drift theory.16. The rainfall caused due to the

presence of mountains in theway of winds is called .............

17. Isochrones are lines joiningplaces with equal .............

18. Leading producer of cementis .............

19. Cadiz, in Spain, is famous for.............

20. Trees shed their leaves inwinter season to .............

21. ............. is the techniqueapplied to measure the depthof the sea.

22. Winter rains in north-westernIndia are caused by ..............

23. The western disturbancescausing winter rains innorthern India originate in.............

24. John’s disease affects .............25. The disease, ‘green ear’,

affects .............26. ............. are nodules on the sea

bed containing a variety ofminerals.

27. The Thar Desert believed to beexpanding. The most suitableway to check it would be by.............

28. ............. consists of masses ofice in layers one above theother.

29. ............. Canal lies on theworld’s largest of trade routesconnecting Europe and Far -East.

30. Strait of Malacca separates............ and ..........

31. ............. grasses are known aselephant grasses.

32. The river Tsangpo (RiverBrahmaputra) flows through............. before entering India.

33. The most valuable cashcropof Brazil is .............

34. The country in which thegreatest waterfall is situated.............

Answers1. Dew Point2. Alluvial

3. Bed4. P-waves (Primary Waves)5. 2/3rd6. Fumarole7. Biosphere8. Political maps9. Mountain Gorillas10. Green land11. Leningrad, Omsk12. Pacific13. rain - shadow area14. Paleontology15. Alfred Wegner16. Orographic rain17. travelling time from a point18. USA19. Cork20. conserve water21. Echo-sounding22. western disturbances23. The Mediterranean region24. cattles25. bajra26. Potato ores27. afforestation28. Hail29. The Suez30. Sumatra and Malaysia31. Savanna32. Tibet33. Coffee34. Zaire (Boyomar falls)

Answer in a Word orSentence1. What is called the study of

lakes and ponds?2. Which gas in the atmosphere

absorbs ultraviolet rays?3. Which is the longest river of

Asia?4. Name the lowest point in

Europe?

2 0 2

5. The highest peak in Hindu-kush mountain range is

6. Which is the largest reef in theworld?

7. Which is the longest freshwater lake in the world?

8. Ferrel’s Law is concernedwith

9. Which is the largest inlandsea in the world?

10. In which country is Kalaharidesert located?

11. Which is the world’s largestRiver Barrage?

12. Which is the largest riverisland in the world?

13. Which river flows into theDead Sea?

14. Which is the deepest lake inthe world?

15. In which ocean is the island‘Diego Garcia’ situated?

16. World’s largest concrete dam17. Which is the only place in the

world where BrowantleredDeer is found?

18. Which famous volcano isknown as the ‘Bonfire ofEurope’?

19. Which is the highest peak inAravalli range?

20. Which is the largest countryin South America?

21. What is the differencebetween the ocean and thesea?

22. Who discovered HawaiIsland?

23. Which is the highestmountain in Australia?

24. Which port is known as the‘Coffee Pot’ in the world?

25. Which is the deepest spot inthe Indian Ocean?

26. Where is Maxwell mountainrange situated?

27. Where is Patagonia Desertsituated?

28. Which is the world’s firstNational Park?

Answers1. Limnology2. Ozone3. Yangtze Kiang4. Caspian Sea5. Trich Mir (7,699 m)6. Queensland Coast of Australia.7. Lake Tanganyika (East Africa)8. Direction of winds9. Mediterranean Sea10. Botswana11. Farakka Barrage12. Majuli (Assam)13. River Jordan14. Lake Baikal15. Indian Ocean (South west of

Sri Lanka)16. Grand Coulee Dam (Washi-

ngton)17. Keibul Lamjao National Park

(Manipur)18. Mount Etna19. Gurushikhar (1772 m)20. Brazil

21. The ocean surrounds thecontinents where as the seais an arm of the ocean

22. Captain james Cook23. Mt. Kosciusko (2226 m)24. Santos (Brazil)25. Wharton Trench (South of

Java)26. Venus27. In Southern Argentina28. Yellow Stone National Park

(U.S.A)

Short Notes1. What are the rocks? How

would you classify them?2. Write short notes on:

(i) Weathering(ii) Denudation &(iii) Springs

3. Write short notes on(i) Canyon (ii) Delta(iii) Geyser (iv) Rift Valley

4. What are earthquakes? Howare they caused?

5. Write short notes on(i) Continental Shelf(ii) Coral Reefs

Farakka BarrageCompleted in 1990, the Farakka Barrage is a dam located 10 kmfrom the Indian side of the border between India and Bangladesh,in the state of West Bengal. India uses it to control the flow of theGanges river. The dam was built to divert the Ganges River waterinto the Hooghly River during the dry season, from January to June,in order to flush out the accumulating silt which in the 1950s and1960s was a problem at the major port of Calcutta on the HooghlyRiver. Bangladesh and India have not had many debates abouthow the Farakka Barrage cuts off Bangladesh’s water supply. Alsoin Bangladesh, the diversion has raised salinity levels,contaminated fisheries, hindered navigation, and posed a threat towater quality and public health. Lower levels of soil moisture alongwith increased salinity have also led to desertification

2 0 3

6. What are tides?7. What are Trade Winds?8. Write short notes on

(i) Roaring Forties(ii) Horse Latitudes.

9. What is the differencebetween Sea Breeze and LandBreeze?

10. Write a short note onMonsoons?

11. What is the differencebetween Cyclones and Anti-Cyclones?

12. What is a rain shadowregion?

13. What is the difference betweenweather and climate?

14. Distinguish between Tributaryand distributary.

15. Write short notes on El Nino& La Nino

16. What are Aurora?17. Water Harvesting18. Artesian Well19 What is Condensation?20. Relief (or Orographic) Rain:21. What is soil and what are its

main constituents?

22. What is soil erosion and howis it caused? What are theconsequences of soil erosion?

23. What is ‘The InternationalDate line’?

24. Write notes on the “PressureGradient Force” and the“Coriolis Force.’’ ?

25. Define the following terms:Typhoon, Hurricane andTornado.

26. What are ‘Ocean Currents’ ?What are their causes?

27. What causes the change ofseasons? Also explain theterms summer solstice, wintersolstice and equinoxes andhow are they caused?

28. What is an equator, latitude,meridian, prime meridian,local or sun time andstandard time?

Answers1. Rocks are the main materials

composing the earth’s crust.Rocks are composed ofminerals. Minerals arenatural inorganic substanceseach with a fairly definitechemical composition and

recognisable crystal form,colour, hardness, lustre,fracture and other physicalcharacteristics. Rocks of theearth’s crust are grouped inthree principle classes.(i) Igneous Rocks: Rockswhich are solidified directlyfrom molten materials arecalled igneous rocks. To acertain extent, all other rocksoriginate from igneous rocks.Therefore, these rocks arecommonly referred to asprimary rocks. These aredivided into extrusive rocks,viz., lava and pumice, orintrusive rocks, such as somegranites which is high incalcium and magnesium andlow in silicon. The intrusiverocks are solidified beneaththe surface while extrusiverocks are solidified at thesurface.(ii) Sedimentary Rocks:These rocks are formed frommaterials which haveaccumulated as the result ofvarious processes, viz, by thebuild - up of particles derivedfrom other rocks, or from theremains of organically formedmatter (from living or onceliving things), or fromdeposits created by chemicalaction. The rocks formed bythe deposition of sediment inwater are conglomerates (e.g.,gravel, shingle, pebbles),sandstones and shales(layered clay and claystone).Peat, lignite, bituminous coaland anthracite are the resultof the deposition of organicmatter. Gypsum, chalk andlimestone are examples ofchemical sedimentation.(iii) Metamorphic Rocks:These rocks were originallyigneous or sedimentary but

Lake BaikalLake Baikal is in Southern Siberia in Russia, located between IrkutskOblast to the northwest and the Buryat Republic to the southeast,near the city of Irkutsk. The name Baikal comes from Baigal or 0930;which in the Mongolian language means “nature”. It is also knownas the “Blue Eye of Siberia”. In Buryat language and Mongollanguage it is called Dalai-Nor, which means “sea lake.”At 1,637 meters (5,371 ft), Lake Baikal is the deepest lake in theworld and is the largest freshwater lake by volume (23,000 km³),containing approximately twenty percent of the world’s total surfacefresh water. Like Lake Tanganyika, Lake Baikal was formed on anancient rift valley and is therefore long and crescent-shaped with asurface area (31,500 km²) less than half that of Lake Superior orLake Victoria.Olkhon, the largest island in Lake Baikal, is the second largest lake-bound island in the world after Manitoulin Island in Lake Huron.

2 0 4

have been changed bypressure, heat or action ofwater. When individualgrains tend to deform andinterlock from existing rocks,they are then called meta-morphic rocks. For example,granite, an igneous rock, maybe metamorphosed intogneiss. Limestone, asedimentary rock, maybecome marble. Sandstonemay be metamorphosed intoquartzite and shale whengreatly compressed into slate.

2. (i) Weathering: It means thebreaking up or disintegrationof rocks. The chief agents ofweathering are temperature,frost, air and rain.(ii) Denudation: It meanslaying bare of a rock whichwas previously covered. Thechief agents of denudation aretemperature, water in itsvarious forms, air and wind,plant life and animal life.(iii) Springs: A spring is aplace where water issues outof the ground spontan -eously.

3. (i) Canyon: A deep andnarrow river valley with steepbank is called a canyon. Themost famous canyon in theworld is that of the GrandCanyon, Colorado (U.S.A).For about 480 kms, the riverflows through a gorge or acanyon the banks of whichare, at some places, more -than one and a half kilometrehigh.(ii) Delta: An alluvial depositshaped like the Greek letter D(delta) formed at mouth ofriver is called delta. Nile deltais well known in the worldand so is the Sunderbans deltain India and Bangladesh.

(iii) Geyser: It is a fountain ofhot water; issuing from a holewhich extends deep into theearth’s crust. The water ishurled high into the air by theforce of steam formed low inthe hole. It contains mineralsin solution and they getdeposited around the holefrom which the water gushesout.(iv) Rift Valley: A long andnarrow valley formed by thesinking of a portion of theearth is called a Rift Valley.

dolomite, accumulated bylime secreting organismsknown a coral polyps. Coralpolyps secrete calcareousmatter to form shells aroundtheir body. A colony of coralscomprises a very largenumber of animals living inshells sticking to each other.As the corals die, the shellsremain deposited and newcorals attach their shells tothe existing deposits. In thismanner corals produce largerock formations. These rockformations made by corals arecalled coral reefs. Eg. Barrierreef, Atoll etc.

6. Alternative rise and fall of thesurface of the sea, approx-imately twice a day, are calledtides. These are caused by thedifference of attractionbetween water and the earth.These are of two types:(i) Spring Tide: At new moonand full moon, the sun and themoon are in the same line asthe earth and both exert theirinfluence together on earth. Sothe tide produced by the sumof their force is consequentlyhigher than usual. This iscalled spring tide.(ii) Neap Tide: At the first andthird quarters of moon, as thesun and the moon are at rightangles to each other; the tideproduced by the difference oftheir force is consequentlylower than usual. This iscalled Neap Tide.

7. These are the winds whichblow towards equator. Theyblow between 5 degrees to 30degrees north and 5 degreesand 30 degrees south latitude.

8. (i) Roaring Forties: These aresteady north-west anti-tradewinds between latitude 45 to50 degrees south.

African Rift Valley. From left to right:Lake Upemba, Lake Mweru, Lake

Tanganyika (largest), and LakeRukwa.

4. An earth quake is a suddentemporary motion or a seriesof motions which originate ina limited region and thenspread out from the place oforigin in all directions. Itcontinues for a while andthen gradually dies out -Earth quakes are causedeither by volcanic eruptionsor by sudden movement ofrock along fault planes.

5. (i) Continental Shelf: It is thatpart of a country or continentwhich is submerged underthe sea and where the wateris not more than 200 metresin depth.(ii) Coral Reefs: Coral reefs aremasses of limestone and

2 0 5

(ii) Horse Latitudes: Thetropical Belts of Calms, i.e.,regions between 30 degrees and35 degrees, are known as HorseLatitudes. The origin of this termis obscure. It is said that thesailing ships carrying horses tothe west Indies were oftenbecalmed between 30 degreesnorth and 35 degrees north andthe sailors were obliged tothrow all the horses overboardand then the ships could move.This part, therefore, came to becalled Horse Latitudes. But nowboth tropics of calm are knownby this name.

9. (i) Sea Breeze: These are thewinds blowing during theday from sea towards landwhich is comparatively hotterthan sea. This is due to the factthat during the day there ishigh pressure on sea and lowpressure on the land and thewind blows from highpressure to low pressure.

(ii) Land Breeze: These are thewinds, which blow during thenight from land to sea, duringwhich sea is hotter than theland.

10. These are the seasonal winds,which blow during the sixmonths of summer fromocean to land and for the sixmonths of winter from landto sea. This is due to the factthat during summer, whenrays of the sun fall verticallyover the Tropic of Cancer, theland becomes comparativelyhotter than the sea. Therefore,the winds blows from the sea.Reverse is the case in winter.They blow over S.E. Asia, EastAsia, Australia, NewZealand etc.

11. Cyclones: These are thewinds, which blow in a spiralform round a centre ofminimum pressure. Theymove anti-clockwise in thenorthern hemisphere. They

cause wind, storm, rains andother changes in the weather.The winter rainfall in punjaband Tamil Nadu is due tocyclones. They occur in theregions of the Indian Ocean.Anti-Cyclones: They are alsowinds, which blow in a spiralform. They move whenpressure at the centre ismaximum and it decreasestowards the edges. They donot bring any rain.

12. Rain shadow region is just onthe opposite of windwardside of the mountain andhence receives little or no rain,e.g., western coast receivesheavy rainfall, while theDeccan Plateau receives littlerainfall as the latter is in therain shadow region.

13. Weather: It is the condition ofatmosphere at a certain timeor period showing pressure,temperature, humidity andrainfall for a shorter duration.Climate: It is the averageweather condition of a placefor a longer period, say, for ayear.

14. A tributary is a small riverwhich confluences a majorriver and increases its volumeof water. It losses its existenceafter meeting the main river.A distributary is a branch ofmain river which comes intoexistence due to the blockadeof the main channel by thedeposition of silt and mud onits bed. It establishes itsexistence after it originatesfrom the main channel.

15. El Nino is a warm current inthe Pacific Ocean that flowssouthward along the westcoast of South America. Itwarms the normally coldwaters of the coast of Ecuador

Alfred Lothar WegenerAlfred Lothar Wegener (Berlin, November 1, 1880– Greenland, November 2 or 3, 1930) was aGerman interdisciplinary scientist andmeteorologist, who became famous for his theoryof continental drift (“Kontinentalverschiebung”or “die Verschiebung der Kontinente” in hiswords).Wegener had early training in astronomy (Ph.D.,University of Berlin, 1904). He became very interested in the newdiscipline of meteorology (he married the daughter of famousmeteorologist and climatologist Wladimir Köppen) and as a record-holding balloonist himself, pioneered the use of weather balloonsto track air masses. His lectures became a standard textbook inmeteorology, The Thermodynamics of the Atmosphere. Wegenerwas part of several expeditions to Greenland to study polar aircirculation, when the existence of a jet stream itself was highlycontroversial. On his last expedition, Alfred Wegener and hiscompanion Rasmus Villumsen went missing in November 1930.Wegener's body was found on May 12, 1931. His suspected causeof death was heart failure through overexertion.

2 0 6

and Peru. El Nino, a spanishterm meaning the child,usually occurs aroundChristmas, and its namerefers to the ‘Christ child’.The unusual warmth killsmany fish and birds and therain accompanied by itcauses disastrous floods inneighbouring coastal area.La Nino is an anotherunusual weather pattern thatbrings unusually coldtemperature to the easternpacific.

16. Auroras are glows of light,hundred of kilometres abovethe Earth’s surface. They areseen when electricallycharged atomic particles,sprayed off the Sun’s surface,collide with atoms in theearth’s atmosphere and makethem release energy in theform of flashes of light.Auroras are the most visibleeffect of the sun’s activity onthe earth’s atmosphere. Theauroras in the northernhemisphere are called theaurora boralis and those inthe southern hemisphereaurora australis. The mostcommon colour in an aurorais green. Auroral displays areassociated with the solarwind, a continuous flow ofelectrically charged particlesfrom the sun. Most aurorasoccur in far northern andsouthern regions.

17. Water Harvesting refers toallowing rain water to sweepinto ground rather than justletting it flow on the ground.This can help in arresting thedecreasing trend of groundwater level besides meetingthe tremendous need ofdrinking water. It can be doneby connecting the roof top rain

water to the ground waterthrough a pipe so that watertable rises by recharging ofground water.

18. Artesian Well: In an artesianwell, underground water isreached by sinking a shaftfrom the surface and waterrises up to the surface byhydraulic pressure. It worksupon the principle that waterkeeps its surface level. TheGreen Artesian basin ofAustralia is the biggest areaof artesian water. In India,these wells are found inGujarat, Tamil Nadu andPondicherry.

19 Condensation is the processin which water vapour in theatmosphere changes intominute droplets of water or icycrystals. Rapid condensationproduces rain, drizzle, snow,hail, frost and dew. Whensmall droplets donot comedown, they remain suspe-nded in the air and are knownas clouds.

of loose fragments whichcovers most of the earth’s landarea. It contains both deca-yed plants and animalsubstances. The four mainconstituents of soils, presentin varying proportion, are:1. Silica, present in soil in

small crystalline grainsform, is the chief consti-tuent of sand.

2. Clay is a mixture ofsilicates and containsseveral minerals such asiron, potassium, calcium,sodium and aluminium.

3. Chalk (calcium carb-onate) provides calcium,the most importantelement for the growth ofplants.

4. Humus is not a mineral,it is an organic matter. Itis formed by decomposedplant remains, animalmanure and dead anim-als and is the mostimportant element in thefertility of the soil.

22. Soil erosion is the removal ofsoil particles by naturalagencies such as water andwind and also as a result ofhuman and animal interfe-rence. Human and animalinterference in a variety ofways leads to soil erosion.Deforestation, over-grazing ofpastures, shifting cultivation,faulty method of cultivation,cultivation of dry crops,diversion of natural drainagecourses, ruts in roads,ditches, improperly constr-ucted terrace outlets (alongwhich running water isconcentrated) etc., areresponsible for soil erosion.Consequences of Soil Erosion:Soil erosion leads to loss ofsoil and badly affects the

Example: Dew on a spider web

20. Relief (or Orographic) Rain:When moist winds strikeagainst mountains, they riseup, expand, cool down andbring rain. Such rain, ascaused by winds strikingagainst mountains, is calledrelief rain.

21. Soil is the loose materialwhich forms the upper layerof the mantle rock; i.e. the layer

2 0 7

runoff. It causes: (1) heavyfloods in rivers; (2) loweringdown of subsoil water level;(3) reduction of soil fertility;(4) silting of streams andwater courses; (5) disappea-rance and downfall ofcivilizations.

23. The International Date line isa zig-zag line that roughlycoincides with the 180thmeridian. When the date lineis crossed from East to theWest, the date must beadvanced by one day, whenthe line is crossed from theWest to the East, the date mustbe set back by one day. TheInternational Date line (themeridian 180°) was chosenbecause it passes through themid-Pacific, where there areno land masses. It goes zig-zag in some places to avoidland and leaves some’ islandgroups wholly on the sameside of the line.

24. The force that drives thewinds, results from horiz-ontal pressure differences,which is produced from theregion of higher pressuretowards the area of lowerpressure is known as thepressure gradient force. Thegreater the difference inpressure between two points,the steeper is the pressuregradient and the higher is thewind speed. Since thedirection of the force is fromhigher to lower pressure areaand perpendicular to theisobars, the initial tendency ofthe wind is to blow parallelto the gradient and at rightangles to the isobars.Due to rotation of the earth,winds do not cross the isobarsat right angles as the pressuregradient force directs but get

deflected from their originalpath. This deviation is theresult of the earth’s rotationand is called the Corioliseffect or Coriolis force. Due tothis effect winds in theNorthern Hemisphere getdeflected to the right of theirpath. It is known as theFerrel’s Law. The coriolisforce changes wind directionbut not its speed. It isnoteworthy that thisdeflection force does not seemto exist until the air is set inmotion and it increases as thewind speed increases.

25. Typhoon is the name givenfor a tropical cyclone in theFar East.Hurricane: is a tropical stormin the Caribbean or WestPacific Ocean, with extremelystrong winds. The wind forcereaches 12 on the BeaufortScale.Tornado is a type ofwhirlwind which is formedby rising air currentsassociated with largecumulonimbus clouds. Itrotates in anticlockwisedirection in the NorthernHemisphere and in clockwisedirection in the SouthernHemisphere.

26. Currents: Ocean currents isthe movement of a sizeablebody of water as a current forfairly long distances along aspecific path. They occur asseasonal and permanentstreams flowing horizontallyat the surface and at deeplevels, they also occur asvertical upswellings of water.Best understood are thesurface currents, many ofwhich have long been studiedand used, especially innavigation.Causes of Currents: Currentsare caused by severalinteracting forces. One of theprime causes, particularly ofsurface currents, is wind. Asthe wind blows over the sea,part of its energy is transferredto the water, which is thusdragged along as a current.Unequal heating of the sea bythe Sun is another majorcause of the oceans’scirculation, particularly in thedeep layers. In polar regions,especially during winter,extremely cold, salty, anddense water sinks far belowthe surface and movestowards the Equator in veryslowly moving layers. At thesame time, warm and lessdense tropical water in theocean’s upper layers movestowards the poles.Other factors that influence theocean’s circulation are theshape and relative positions’of the continents; the presenceof barrier-like island chains;and local winds. The currentswax and wane with theseasons, mainly because of theshifting of the winds. Currentsalso meander and shift theircourses from year to year.

A tornado in central Oklahoma. Thetornado itself is the thin tube reaching

from the cloud to the ground. Thelower part of this tornado is

surrounded by a translucent dustcloud, kicked up by the tornado’s

strong winds at the surface

2 0 8

27. The change of seasons ismainly due to the revolutionof the earth. The earth’s axisis inclined to the plane of itsorbit and always points inthe same direction.(1) 21 st June: At this time it

is summer in theNorthern Hemispherebecause (a) The NorthPole is inclined towardsthe sun; so days arelonger than nights. Nearthe North pole there is aday of 24 hours. (b) Thesun’s rays fall verticallyon the Tropic of Cancer.This position of the Earthis called SummerSolstice. In the SouthernHemisphere there will bewinter season because (a)the South Pole is inclinedaway from the sun. Sodays are shorter thannights, the South Polehave continuous nightsfor 24 hours. (b) the Sun’srays are oblique.

(2) 22nd December: At thistime it is winter in theNorthern Hemisphereand summer in theSouthern Hemispherebecause (a) the North Poleis inclined away from thesun while the South Poleis towards the sun, sodays are shorter in theNorthern Hemisphereand longer in theSouthern Hemisphere. (b)the Sun’s rays are verticalin the South at the Tropicof Capricorn and obliquein the North. Thisposition of the Earth iscalled Winter Solstice.

(3) Equinoxes: On 21stMarch and 23rd Septem-ber the season is either

Spring or Autumn because(a) both the North Poleand the South Pole areinclined equally towardsthe sun; days and nightsare equal everywhere; allpoints on earth have a 12hour day and 12 hournight. (b) Sun’s rays fallvertically on the equator.These two positions ofthe earth are calledequinoxes due to theequal length of the daysand nights.

28. Equator is an imaginary circleon the surface of the earthmidway between the poles.latitude is the angular dista-nce measured North or Southof the Equator from the planeof the Equator.Meridian means “Middayline”. It is imaginary linejoining North and SouthPoles, which when any placecome directly below the sun,it has its midday everywhereon it. Prime Meridian is themeridian which passesthrough Greenwich, a place

near London. It is the zerodegree longitude.Local Time or Sun Time of aplace is the time which isreckoned according to thetime when the sun’s altitudeis the highest at that place. Atthis time the shadow of avertical rod fixed in theground is the shortest. If atthis time we set our watch at12 O’clock, it will indicatelocal time.Standard Time: If every placewere to use its own local timethat would cause confusion inadministration and otheractivities; so the local time of aplace generally in the middle ofthe country, is used everywherein that country as the StandardTime of that country and is takento be uniform throughout.Standard Time of India is thelocal time of a place nearAllahabad situated at 82½o Elongitude. Some countries onaccount of their distances havemore than one standard time.Russia has 11 such differenttimings.

SavannaA savanna or savannah is a tropical or subtropical woodlandecosystem. Savannas are characterised by the trees being sufficientlysmall or widely spaced so that the canopy does not close. It is oftenbelieved that savannas are characterized by widely spaced, scatteredtrees, however in many savanna communities tree densities arehigher and trees are more regularly spaced than in forestcommunities.The open canopy allows sufficient light to reach the ground tosupport an unbroken herbaceous layer consisting primarily of C4grasses. Savannas are also characterised by seasonal wateravailability, with the majority of rainfall being confined to one seasonof the year. Savannas can be associated with several types of biomes.Savannas are frequently seen as a transitional zone, occurringbetween forest regions and desert regions.

2 0 9

Important Terms inGeography Anticlines and Synclines: An

anticline is a fold with stratasloping downwards on bothsides from a common crest toform an arch. The top of thearch, being pressed upwardis the loosest and weakestpart and as such is quicklyeroded. A syncline is a lowtrough like area in bedrockwith rocks inclined togetherfrom opposite sides. the rocksat the lowest part are undergreat pressure from all sides;they become compact andhard and erode slowly.

Atoll: A coral reef in the shapeof a horse shoe or ring with alagoon in the centre, e.g.Murora Atoll in the PacificOcean.

Asthenosphere: Softsemifluid layer of rock onwhich the earth’s continentsand ocean floor float. Theasthenosphere is a part of theearth’s mantle, the rest ofwhich is solid both above andbelow.

Attrition: The constantwearing down of pieces ofrock into even finer particlesas they are carried of along bywind, water or ice.

Bog: An area of water-logged,spongy ground with rottingvegetation lying on thesurface. Eventually the layerturns into a layer of peat.

Bora: A cold and dry windwhich blows along theeastern coast of the AdriaticSea and northern Italy inwinter.

Cloud Burst: A phenomenonin which a huge mass of

moisture-carrying cloudsbursts into a heavydownpour on account ofcondensation of its entirevolume of water vapour at thesame time.

Coriolis Force: The forceexerted on the atmosphere byearth’s rotation.

Crater: Is the small mouth ofa volcano. It is usually cup-shaped and serves as a ventfor lava to flow out of thevolcano.

Creek: A small stream; asmaller inlet or tidal estuaryof a river.

Escarpment: A steep inlandcliff. An escarpment is foundwhere layers of hard rockslope upwards to the surfaceover softer rocks below.

Estuary: A channel formed bymixing of sea and river water,e.g., Thames Estuary.

Foehn: A warm dry windwhich blows down the ice-ward slope of a mountain, bestknown in the valleys of thenorthern alps.

Gale: A strong wind thatblows at a speed of 62-101kmph.

Isogonic lines: Contour linesof magnetic declination.

Isohyte: A line drawn on amap joining places receivingequal amount of rainfall overa certain period.

Isoneph: A line on a mapjoining places having equalaverage cloudiness over acertain period.

Isostasy: The state of balanceor equilibrium that is said toexist between highlands andlowlands of the earth due todifference in the density oftheir respective rock material.

Khamsin: The hot, dry windexperienced in Egyptcorresponding to the Siroccoof North Africa. ‘Khamsin’ inthe Arabic word for 50; thewind is said to blow duringthe period of 50 days fromApril to June.

Kurosiwo: Warm oceaniccurrent of the Pacific Oceanwhich flows near the eastcoast of Japan and ultimatelydrifts along the west coast ofCanada. It raises thetemperature of Canada andJapan.

Smoke Screens: Smoke cloudsformed by firing smoke shells,dropping smoking bombs,burning smoke pots oroperating mechanical smokegenerators in war to concealtheir movements fromenemies.

Sirocco: A hot, normally dryand dust - laden wind thatblows from the deserts ofNorth Africa across theMediterranean into SouthEurope. It occurs only inspring. The name ‘Sirocco’ isalso applied to any hotoppressive wind.

Stratus clouds: Clouds whichare like a dark grey sheetextending from one side ofhorizon to the other and haveuniform base.

Terrain: The physicalcharacteristics and features ofany stretch of country.

Troposphere: Troposphere isthe lower most layer of theatmosphere. It extends upto 8km at the equator and 16 kmat the poles. The word‘‘Tropo’’ means ‘‘change’’.This layer acts as a warmblanket to moderate theextremes of outer space. The

2 1 0

thickness is greater at theequator, because the heatedair rises to greater heights.

Stratosphere: Stratospherelies above the troposphere. Itis a region of uniformtemperature extending froman altitude of about 11 kmabove the earth to a height ofnearly 50 km. It is free fromwater vapour, clouds anddust. The upper part of thislayer has plenty of ozonewhich affords protection tohuman beings on the earthagainst the fatal effects of UVradiations. It also providesideal conditions for flyingaeroplanes.

Ionosphere: It extends from 65km to nearly 400 km above theearth’s surface. It is anelectrically charged layercharacterised by theionisation of atoms. Due to thepresence of electric charge inthis layer, radio wavestransmitted from the earth arereflected back to the earth bythis layer. Its also benefitsman by absorbing the sun’sdeadly rays. Aurora areproduced by chargedparticles from the suncaptured by the earth’smagnetic field at a height ofabout 100 km.

Longtitudes are equi-distantlines drawn east and west ofthe Greenwich meridian.They denote the angulardistances of a place due eastor west of the Greenwichmeridian. There are 360meridians of longtitudes. Onehour is equal to 15o oflongtitude. Longtitude is animportant factor indetermining the time in allparts of the world. Local timeof a place is calculated with

respect to the mid dayposition of the sun at thatplace.

Torrid Zone: which is thehottest zone lies between 23½o

north and 23½o south. ie.,between the Tropic of Cancerand Tropic of Capricorn.

Temperate Zone : liesbetween 23½o N and 66 ½o Nis the North Temperate zoneand South Temperate zonelies between 23½o S and66½oS. This zone has amarked annual range oftemperature.

Frigid zone lies between 66½o

N and 90oN in the case ofnorth frigid zone and 66½o Sand 90o S in the case of southfrigid zone. They areextremely cold regions.

Hurricane Ivan: TheHurricane Ivan is a tropicalcyclone. The winds are moreviolent and cause severedamage to life and property.Recently, it occured in theCarribean Sea, and movedforward to the Gulf of Mexico.Further it went upward andmade vast destruction in theU.S.A.

Tropic of Cancer: Tropic ofcancer is an imaginary line oflatitude of 23½o N. It marksthe limit of that portion of theearth where the sun’s rays fallvertically on June 21st.

Tropic of Capricorn: In thesouthern hemisphere, animaginary line of latitude of23½o S is termed as tropic ofcapricorn. This line marks thelimit of that portion of theearth where the sun’s rays fallvertically on December 21st.

Chinook: A very warm, drywind that descends themountain slopes causing

rapid melting of snow.Sometimes, during springseason, it triggers avalanches.It is developed when warm,moist air is drawn towards amountain range from an areaof relative high pressure. Thiswind blows in Andes andRockies mountains.

Equatorial Regions: Theequatorial region is foundbetween 5o and 10o north andsouth of the equator. The mid-day sun is always near thevertical and it is overheadtwice a year, at the equinoxes.Uniformity of temperaturethroughout the year is themost outstanding feature ofthe region. The relativehumidity is very high. Here,annual rainfall is between160 and 350 cm. It is of theconvectional type. Squallsand thunderstorms occurfrequently, followed bybrilliant sunshine. The fourseasons of the temperaturezone are unknown.

Tsunamis: It is the Japanesename given to the huge wavescaused by an earthquake.Tsunamis are quite commonalong the coasts of Japan andother regions in the pacificocean.

Fold mountains: Mountainswhich have been thrown intomassive folds or ridges by theearth movements are knownas fold mountains. They arecharacterised by ruggednessof relief. The higher and morepointed the peaks, the morerecently the mountain wasformed. Some young foldmountains are theHimalayas, the Alps, theRockies and the Andes andsome old fold mountains arethe Pennines, Applachians,

2 1 1

Cape Ranges of South Africaand the Great DividingRange of Australia.

Block mountains: Blockmountains are formed whena mass of land was pushedup between parallel cracks orfaults in the earth’s crust orby sinking of the land aroundthem. They are usually verysteep-sided and are flat-topped. Black forest; Mesetaare examples of blockmountains.

Rift Valley Lakes: Lakesformed by the movements ofthe earth cause subsidence inthe earth’s crust and thehollows lying in the bed of theRift Valley is termed as RiftValley lake. Lake Baikal inSiberia, the Dead Sea areexamples of this type of lakes.

Lava Dam Lakes: Sometimes,a lava stream may flow acrossa valley and form a naturaldam. It is called lava damlakes. The sea of Galilee inPalestine was formed by lavawhich flowed across theJordan Valley.

Crater Lakes: Crater lakesoccur on the extinctvolcanoes. They are circularand steep-sided. Mar’smission space craft ‘spirit’landed on Gustav Crater.

Temperate Grasslands: Thetemperate grasslands arefound between latitudes 40o

and 55o N and S. They lie faraway from the influence of thesea in the heart of thecontinents, and most of themare interior lowlandsconsisting of level, generallytreeless, plains. The temperategrasslands are known bydifferent names in differentcountries. They are known as

‘prairies’ in North America,‘pampas’ in South America,‘veldt’ in Southern Africa,‘downs’ in Australia, ‘pustaz’in Hungary and ‘steppes’ inRussia.There is no typicaltemperature for any onepriarie type region. However,as all the grasslands in thenorthern hemisphere lie inthe interior of the largecontinents the climate is veryextreme. Summers are shortand quite warm. There isabundant sunshine and theskies are clear. The regionfalls in the zone of thewesterlies. The rainfall in thegrasslands are of convectionaltype, but very light.

Savannah is a region whichlies on both sides of theequator roughly between 5degrees and the tropics. Heresummers are hot and moistand winters are warm anddry. Characteristic vegetationis tall grass.

Taiga: This region liesbetween 55o and 70o C innorthern hemisphere only. Itstretches as an almostcontinuous belt acrosssouthern Canada, NorthernEurope and Russia. TheTundra region lies on thenorth and the temperategrasslands on the south. In theTaiga region, summers areshort, lasting for 3 or 4months and winters are coldand severe. For 6 to 7 months,this region has temperaturesbelow freezing point. In thisregion lies Verkhoyansk, the‘cold pole’, colder than Arcticregion. Rainfall varies from25 to 100 cm. Most of the raincomes from cyclonic weather.

Richter Scale: It is a scale usedfor measuring the magnitudeof the earthquake at its focus.According to it, themagnitude ranging ‘7’ issevere and ‘8’ is devastating.

Seismograph: It is used tomeasure the intensity andlocation of earthquake.

Norwesters: Norwesters areviolent thunderstorms whichoccur on the passages of astrong wind that approachesfrom the west or north-west,hence the name ‘norwesters’.They occur in the Bengal andAssam region during the hotseason before the onset of thesouth-west monsoon.

Rainbows: Rainbows arecaused by refraction andinternal reflection of lightfrom the sun in raindrops.Each raindrop acts like a tinyprism which breaks up thewhite light into the primarycolours. In the main rainbowthe colours are: violet, indigo,blue, green, yellow, orangeand red (VIBGYOR). We areable to see a rainbow onlywhen we are facing the fallingraindrops with the sunbehind us.

GreenlandGreenland is a self-governingDanish province locatedbetween the Arctic and AtlanticOceans. Though geographi-cally and ethnically an Arcticisland nation associated withthe continent of NorthAmerica, politically andhistorically Greenland isclosely tied to Europe,specifically Iceland, Norwayand Denmark. It is the largestisland in the world that is notalso considered a continent.