Shaping of the Earth's Surface (Earth ki Surface ka Banna aur Badalna): Class 9 Social Science Chapter 2 Hinglish mein

Tumhare school ke neeche ki zameen bilkul sthir lagti hai. Phir bhi Himalaya har saal kuch millimetre upar uth raha hai. Brahmaputra pahaad jitni silt Bay of Bengal tak le jaati hai, aur samundar India ke coastline ko lagaataar kutarta rehta hai. Earth ki surface kabhi poori tarah ban kar khatam nahi hoti. Andar gehraai se aane wali forces use upar dhakelti aur todti hain, jabki baarish, nadiyaan, barf, hawa aur waves use ghisti hain aur kahin aur dobara banaati hain.

Western Ghats, Narmada valley, Chota Nagpur plateau, Ganga plain, Jaisalmer ke dunes aur Puri ka beach, sab ek-ek landform (स्थलरूप) hain. Inhe forces ki do teams banaati hain. Internal forces, jinhe Earth ki andar ki garmi se taakat milti hai, crust ko uthaati, modti aur todti hain. External forces, jaise behta paani aur wind, dheere-dheere oonchi jagahon ko ghis kar neeche karti hain aur bacha hua maal neechi jagahon par phaila deti hain. Yeh chapter dono teams ko dekhta hai, aur phir un disasters ko jo tab aati hain jab zameen achaanak badalti hai.

2.1 Plate tectonics

World map dekho. South America ka ubhra hua hissa West Africa ke mod mein aaraam se fit ho jaayega, jaise kisi page ke do phate hue tukde. Aisi paheliyon ki wajah se scientists ne poochha ki kya continents chalte hain. 1967–68 mein American geophysicist W. Jason Morgan ne Earth ke bahari shell ko aise rigid blocks ka set bataya jo ek doosre ke against chalte hain. Dan McKenzie aur Robert Parker bhi lagbhag usi samay isi idea tak pahunche. Unka idea badh kar plate tectonics ki theory bana, jo aaj ek simple picture se mountains, ocean basins, earthquakes aur volcanoes ko samjhaati hai.

2.1.1 Earth ke andar

Abhi tak koi bhi Earth mein lagbhag 12 km se zyada gehra drill nahi kar paaya hai. Scientists iske andar ke baare mein earthquake waves se seekhte hain, jo alag-alag materials se guzarte hue mudti hain aur apni speed badalti hain. Yeh suraag teen main layers dikhaate hain, bilkul aam ke chhilke, gude aur guthli ki tarah (Fig. 2.1).

• Crust: patli, solid bahari chamdi jis par hum rehte hain. Oceans ke neeche yeh sirf lagbhag 5–10 km moti hai, lekin continents ke neeche 30–70 km, aur Himalaya jaisi oonchi ranges ke neeche sabse moti hai.
• Mantle: garam rock ki bahut moti layer jo lagbhag 2,900 km gehraai tak jaati hai. Yeh zyaadatar solid hai, lekin laakhon saalon mein bahut dheere beh sakti hai, jaise dhoop mein chhodi gayi toffee.
• Core: centre, jo mainly iron aur nickel se bana hai. Outer core liquid metal hai; inner core bahut zyada pressure ke neeche ek solid ball hai, aur planet ka sabse garam aur sabse dense hissa hai.

Geographers Earth ke bahari hisse ko is hisaab se bhi baantte hain ki woh kitna sakht hai. Crust aur mantle ka upar wala rigid hissa milkar lithosphere (स्थलमंडल) banaate hain, jo lagbhag 100 km mota hai. Iske neeche asthenosphere hai, ek garam layer jo naram aur thodi pighli hui hai. Lithosphere ko ek tute hue uble ande ke chhilke ki tarah socho. Yeh tukdon mein bata hai, aur har tukda neeche ki naram layer par sarak sakta hai.

2.1.2 Tectonic plates aur woh kyun chalti hain

Lithosphere ka har tukda ek tectonic plate (विवर्तनिक प्लेट) hai: solid rock ka ek vishaal slab, jo aksar hazaaron kilometre chauda hota hai. Plates saal mein kuch centimetre khisakti hain, lagbhag utni tezi se jitni tumhare naakhun badhte hain. Indian Plate tez plates mein se ek hai, jo saal mein lagbhag 4–5 cm north-east ki taraf chalti hai. Yeh bahut chhota lagta hai, lekin 10 million saalon mein yeh 400–500 km ho jaata hai.

Geographers plates ko is hisaab se bhi sort karte hain ki unke upar kya hai. Kuch par mainly zameen hai (continental plates), kuch par mainly sea floor (oceanic plates), aur kai par dono ka mix hai (mixed plates). Oceanic crust continental crust se patli lekin bhaari hoti hai, aur yeh tab bahut maayne rakhta hai jab do plates takraati hain.

• Saat major plates: Pacific, North American, South American, Eurasian, African, Indo-Australian aur Antarctic.
• Minor plates inke beech ke gaps bharti hain, jaise Nazca, Arabian, Philippine aur Caribbean plates.
• Kai naye maps Indo-Australian Plate ko Indian Plate aur Australian Plate mein baantte hain, kyunki dono hisse thoda alag tarah se chalte hain.

Itne vishaal slabs ko kaun chalata hai? Jawab mantle mein hai. Core se aur rocks ke radioactive elements se garmi bahar nikalti hai. Neeche ke paas ki mantle rock garam hoti hai, thodi halki ho jaati hai aur bahut dheere upar uthti hai. Upar pahunch kar yeh side mein phailti hai, thandi hoti hai, bhaari ho jaati hai aur phir se neeche doobti hai. Yeh dheemi loops convection currents (संवहन धारा) hain. Carpet ke neeche ek dheemi conveyor belt ki tarah, yeh plates ko apne saath le chalti hain (Fig. 2.2).

2.1.3 Plate boundaries

Sabse bade badlaav wahan hote hain jahan plates milti hain, yaani plate boundary ke saath. Plates teen tarah se mil sakti hain, aur har tareeka zameen par apni alag chhaap chhodta hai (Fig. 2.3).

• Convergent boundary (plates ek doosre ki taraf chalti hain). Jab do continental plates takraati hain, to koi bhi aasaani se neeche nahi jaati, isliye crust sikud kar mudti hai aur upar uth kar fold mountains banaati hai. Himalaya isi tarah utha jab Indian Plate Eurasian Plate mein dhakelti gayi. Jab ek oceanic plate continental plate se milti hai, to bhaari oceanic plate neeche mud kar uske neeche khisak jaati hai (ise subduction kehte hain). Sea floor par ek gehri trench banti hai, aur pighalti rock upar uth kar zameen par volcanoes ko khuraak deti hai, jaise Andes mein. Dono tarah ki takkar par strong earthquakes aam hain.
• Divergent boundary (plates alag hoti hain). Garam mantle rock gap mein upar aati hai, pressure kam hone par thodi pighalti hai, aur sakht hokar new crust banti hai. Oceans ke neeche isse lambi underwater mountain chains banti hain jinhe mid-ocean ridges kehte hain; Mid-Atlantic Ridge Atlantic ke beech se guzarti hai, aur Iceland uske upar baitha hai.
• Transform boundary (plates ek doosre ke paas se sarakti hain). Yahan crust na banti hai na khatam hoti hai, lekin plates atak jaati hain, tanaav jamaa hota hai aur phir jhatke se chhootti hain, jisse earthquakes aate hain. California, USA ka San Andreas Fault sabse mashhoor example hai.

2.1.4 Earthquakes, volcanoes aur Ring of Fire

Kyunki plates zyaadatar apne edges par hi dhakka-mukki karti hain, isliye earthquakes aur volcanoes kahin bhi bikhre hue nahi hote. World map par yeh patli belts banaate hain jo lagbhag line-dar-line plate boundaries se match karti hain. Sabse vyast belt Pacific Ocean ke chaaron taraf ghoomti hai. Yeh New Zealand se Indonesia, Philippines aur Japan hote hue Alaska tak jaati hai, aur phir Americas ke west coast ke saath neeche Chile tak. Is ghode ki naal jaise shape ko Ring of Fire kehte hain. US Geological Survey ke anusaar duniya ke lagbhag 90 per cent earthquakes isi ke saath aate hain, aur duniya ke zyaadatar active volcanoes bhi yahin hain.

India Pacific se door hai, lekin earthquakes se surakshit nahi hai. Indian Plate abhi bhi Asia mein dhakel rahi hai, aur Himalaya aur North-East ke saath tanaav jamaa hota rehta hai. India ke seismic zones ke national map par sabse zyada risk wala zone Himalaya, North-East, Rann of Kachchh aur Andaman and Nicobar Islands ke hisson ko cover karta hai.

• Drop, cover and hold on: kisi mazboot table ke neeche jao aur hilna rukne tak use pakde raho; khidkiyon aur oonchi almaariyon se door raho.
• Agar tum bahar ho, to buildings, pedon, poles aur wires se door kisi khuli jagah par jao.
• Lift ka use mat karo. Hilna rukne ke baad dhyaan se bahar niklo aur aftershocks ke liye taiyaar raho.
• Sabse zaroori hai bachaav: earthquakes ke hisaab se design ki gayi buildings, aur emergency kit ke saath ek family plan.

Volcano crust mein ek opening hai jisse pighli rock, gases, ash aur rock ke tukdon ke saath bahar nikalti hai. Pighli rock zameen ke neeche magma kehlaati hai aur surface par pahunchne ke baad lava. Baar-baar ke eruptions in materials ko jama karke ek pahaad bana dete hain. Zyaadatar volcanoes wahan hote hain jahan plates alag hoti hain ya jahan ek plate doosri ke neeche doobti hai.

To plate tectonics samjhaati hai ki continents aur oceans jahan hain wahan kyun hain, mountains kyun uthte hain, aur kuch jagahein doosri jagahon se kahin zyada baar kyun hilti hain. Yeh aakhri baat bahut kaam ki hai. Plate boundaries aur pichhle quakes ko map karke planners hazard zones mark kar sakte hain, wahan building ke sakht rules bana sakte hain aur logon ko pehle se taiyaar kar sakte hain.

2.2 Weathering aur erosion

Internal forces zameen ko upar banaati hain. External forces use dana-dana karke todti hain, aur kabhi rukti nahi. Zyaadatar kaam do processes karte hain. Weathering rock ko dheela karke todta hai, aur erosion toote tukdon ko door le jaata hai. Hazaaron se laakhon saalon tak saath kaam karke yeh mountains ko neecha karte hain, valleys kaatte hain, plains phailaate hain, aur caves, cliffs aur deltas banaate hain.

2.2.1 Weathering

Mandir ke talaab ki puraani pathar ki seedhiyaan gol aur bhurbhuri hain; granite ka naya slab nukeele kinaaron wala hai. Yeh farak weathering (अपक्षय) ka hai: rock ka wahin jahan woh padi hai tootna, bina kahin le jaaye. Iske teen types hain (Fig. 2.4).

• Physical weathering rock ko chhote tukdon mein todta hai, bina yeh badle ki woh kis cheez se bani hai. Thar desert mein rock din mein tezi se garam hoti hai aur raat mein thandi; baar-baar phoolne aur sikudne se uski bahari layers mein darar padti hai. Ladakh mein paani daraaron mein ghusta hai, jamta hai, phailta hai aur rock ko wedge ki tarah alag kar deta hai.
• Chemical weathering khud minerals ko badal deta hai. Baarish ka paani hawa se carbon dioxide ghol leta hai isliye thoda acidic hota hai, aur yeh limestone aur marble ko kha jaata hai. Oxygen rocks ke iron se react karti hai aur unhe reddish-brown kar deti hai, bilkul jaise iron ke gate par jung lagta hai.
• Biological weathering jeevit cheezein karti hain. Puraane kile ki deewar se ugne wala peepal ka paudha ek daraar mein jadein bhejta hai aur dheere-dheere pattharon ko alag kar deta hai. Bil banane wale jaanwar, aur lichens jo halke acids chhodte hain, bhi rock ko dheela karte hain.

Weathering sirf todne ka kaam nahi karta. Isse bane baareek kan samay ke saath sadte patton aur jeevit organisms ke saath milkar soil ban jaate hain. Gehun ya chawal ka har khet aisi rock par ugta hai jise weathering ne bahut pehle toda tha.

2.2.2 Erosion

Erosion (अपरदन) wahan shuru hota hai jahan weathering rukta hai: dheeli soil aur rock ko koi chalta hua agent utha kar door le jaata hai. Kisi nangi slope par monsoon ki tez baarish dekho, to tum ise hote dekh sakte ho, jab keechad bhara paani dhalaan se neeche behta hai. Erosion ke kai agents hain.

• Water erosion: baarish ki boondein, runoff ki chaadarein, gullies aur nadiyaan soil ko baha le jaati hain. Chambal river ke saath ki gehri ravines isi tarah kati hain.
• Wind erosion: jahan baarish kam ho aur zameen nangi ho, jaise western Rajasthan mein, wahan hawa ke jhonke soil ki dheeli upar wali layer uda le jaate hain.
• Glacial erosion: glacier rock ke tukdon ko apne mein jama leta hai aur unhe ek vishaal file ki tarah apne bed par ghisata hai.
• Coastal erosion: waves kinaare par chot karti hain aur zameen ko peeche ghis deti hain.

Erosion landforms ko shape deta hai, lekin yeh logon ki zindagi aur kaam ko bhi shape deta hai.

• Farmers patli, upjaau topsoil kho dete hain jise banne mein sadiyaan lagi thi, isliye fasal ghatti hai aur zyada fertiliser chahiye hota hai.
• Nadiyon aur coasts ke paas rehne wale parivaar apne khet, ghar aur gaanv ki sadkein paani mein samaate dekh sakte hain. Brahmaputra mein river island Majuli ne bank erosion se apna bada hissa kho diya hai.
• Builders aur miners ko asthir slopes, dhanste foundations aur girte gaddhon ka saamna karna padta hai.
• Tourism aur fishing ko nuksaan hota hai jab beaches beh jaate hain aur nadiyaan silt se bhar jaati hain.

2.2.3 Zameen ko erosion se bachaana

Slope par paani jitni tezi se behta hai, utni zyada soil le jaata hai. Isliye pahaadon par soil bachaane ka lagbhag har tareeka paani ko dheema karke use zameen mein samaane dene ki koshish karta hai (Fig. 2.5).

• Contour trenches (continuous contour trenches, ya CCTs): contour line ke saath, yaani same height wale points ko jodte hue, khodi gayi uthli trenches, taaki har trench runoff ko pakde aur use zameen mein samaane de.
• Contour bunding: slope ke aar-paar ek hi level par mitti ya pattharon ki neechi ridge. Runoff iske peeche ruk jaata hai, isliye uski silt wahin baith jaati hai aur paani ko andar risne ka samay milta hai.
• Terracing: pahaadi dhalaan ko samtal kheton ki seedhiyon mein kaatna. Paani neeche bhaagne ki jagah har samtal step par ruka rehta hai. Uttarakhand, Himachal Pradesh aur North-East mein terraced fields aam nazara hain.
• Check dams: mausami naale ke aar-paar pathar ya mitti ki neechi deewarein. Inke peeche paani jama hota hai, uski silt baith jaati hai, aur zyada paani bhaag jaane ki jagah zameen mein rista hai.

2.3 Agents of gradation

Agar zameen ko phir se upar dhakelne wala kuch na ho, to external forces aakhir mein har continent ko ghis kar ek neechi, samtal surface bana dengi. Yeh samtal karne wali natural forces agents of gradation hain. Har agent material ko erode karta hai (ghis kar hataata hai), use transport karta hai, aur kahin neeche deposit karta hai (gira deta hai). Isliye har agent landforms ki do families banaata hai: kuch erosion se kate hue aur kuch deposition se bane hue (Table 2.3).

2.3.1 Behta paani

Nadiyaan zameen par sabse vyast agents hain. Pahaadon se samundar tak nadi ka safar aam taur par teen hisson mein baanta jaata hai, aur har hisse ke apne landforms hote hain (Fig. 2.6).

• Upper course: slope teekhi hai aur paani tez, isliye nadi zyaadatar neeche ki taraf kaatti hai, aur gehri V-shaped valleys, gorges, waterfalls aur rapids banaati hai.
• Middle course: slope halki hoti hai, nadi neeche se zyada side mein kaatti hai, aur loops mein ghoomne lagti hai jinhe meanders kehte hain. Kate hue loops oxbow lakes ban jaate hain, aur baadh silt ko ek chaude floodplain par phaila deti hai.
• Lower course: zameen lagbhag samtal hai aur nadi dheemi, isliye woh apna zyaadatar load deposit karti hai, oonche kinaare banaati hai jinhe levees kehte hain, aur apne muhaane par ek delta. Jahan koi naala pahaadon se tezi se nikal kar plain par aata hai, wahan woh apna load pankhe ki shape mein gira deta hai jise alluvial fan kehte hain.

Waterfall

Waterfall wahan banta hai jahan nadi apne bed ke kisi teekhe step se neeche girti hai. Yeh step aksar wahan banta hai jahan hard rock ki patti soft rock ke upar ho. Nadi soft rock ko zyada tezi se ghisti hai, isliye hard layer ek chhajje ki tarah latki reh jaati hai. Girta paani neeche ek gehra plunge pool bana deta hai aur cliff ke neeche ka hissa khokhla karta hai, jab tak chhajja toot nahi jaata. Phir poora process thoda aur upstream se dobara shuru hota hai, aur peeche ek gorge chhod jaata hai (Fig. 2.7).

Waterfalls logon ke liye bhi maayne rakhte hain. Karnataka mein Sharavati river par Jog Falls 253 m neeche girta hai, aur paas ke power stations usi nadi se hydroelectricity banaate hain. Goa ka Dudhsagar, Kerala ka Athirappilly aur Chhattisgarh ka Chitrakote jaise falls tourists ko kheenchte hain aur local guides, dukaanon aur homestays ko sahaara dete hain. Kai falls local tyohaaron aur maanyataon se bhi jude hain.

Meander aur oxbow lake

Halki zameen par nadi shaayad hi seedhi behti hai. Kisi bhi mod par bahar ki taraf ka paani tez chalta hai aur kinaare ko kaatta hai, jabki andar ki taraf ka dheema paani sand aur silt gira deta hai. Isliye bahari kinaara peeche hatta rehta hai aur andar ka kinaara badhta rehta hai, aur mod phool kar ek loop ban jaata hai jise meander (विसर्प) kehte hain. Samay ke saath loop ki gardan itni patli ho jaati hai ki baadh use seedha kaat deti hai. Chhoota hua loop ek mudi hui oxbow lake ban kar reh jaata hai (Fig. 2.8).

Meandering nadiyaan apne floodplains par upjaau silt jama karti hain, isliye gaanv aur khet unke saath ikattha hote hain, aur nadiyaan sinchaai ke liye paani aur kahin-kahin naavon ke raaste deti hain. Oxbow lakes samriddh wetlands ban jaati hain: Begusarai mein Kabartal (Kanwar Lake), jo Bihar ki pehli Ramsar site hai, Burhi Gandak ka ek puraana loop hai jo bahut pehle kat gaya tha. Log lambe samay se aisi nadiyon ka faayda uthaate aaye hain. Kallanai, yaani Grand Anicut, Tiruchirappalli ke paas Kaveri ke aar-paar lagbhag do hazaar saal pehle bana tha, aur iska shrey Chola raja Karikāla ko diya jaata hai. Yeh ab bhi paani ko canals mein mod-ta hai jo Kaveri delta ki sinchaai karti hain.

Delta

Jab nadi aakhir mein kisi samundar ya jheel mein pahunchti hai, to woh achaanak dheemi ho jaati hai aur door upstream se laayi silt gira deti hai. Layer-dar-layer yeh deposits ek neecha, pankhe jaisa ya triangle jaisa plain banaate hain jise delta kehte hain. Nadi kai chhote channels mein bat jaati hai, jinhe distributaries kehte hain, jo uske upar se ghoomte hue samundar tak jaate hain (Fig. 2.9). India ka east coast deltas se bhara hai: Ganga–Brahmaputra, Mahanadi, Godavari, Krishna aur Kaveri ke deltas.

Crores log deltas par kyun rehte hain? Sabse pehle khaana: Kaveri delta ko Tamil Nadu ka rice bowl kehte hain, aur Ganga–Brahmaputra delta mein chawal aur jute ugta hai. Jahan nadi ka paani samundar se milta hai, wahan machhliyaan, kekde aur jhinge khoob palte hain. Naavein channels ke saath saamaan le jaati hain, isliye market towns aur ports badhte hain. Iski keemat hai risk: zameen neechi aur samtal hai, isliye nadi ki baadh, storm surges aur cyclones tezi se iske upar phail sakte hain.

2.3.2 Waves aur currents

Waves aur currents din-raat paani ko coast ki taraf dhakelte rehte hain. Jahan woh sand aur kankad girate hain wahan beaches banaate hain; jahan woh rock par hamla karte hain wahan use anokhi shapes mein kaat dete hain. (Waves aur currents ko khud tum apni textbook ke Part 2 mein padhoge.)

Jahan waves ki energy kam hoti hai, jaise bays mein aur halki dhalaan wale kinaaron par, wahan woh apne saath laaya sand aur shingle gira deti hain. Yeh deposit beach hai, aur har tide aur current ise thoda badal deta hai. Kinaare ke saath chalne wale currents sand ko kheench kar lamba sand bar bhi bana sakte hain, jo kabhi-kabhi ek lagoon ko gher leta hai. Aisa hi ek bar Odisha ki Chilika lake ko Bay of Bengal se alag karta hai. Chennai ka Marina aur Puri aur Goa ke beaches visitors ko kheenchte hain aur hotels, stalls aur fishing communities ko sahaara dete hain. Yeh natural shock absorbers ka kaam bhi karte hain jo storm waves ki taakat gharon tak pahunchne se pehle hi jhel lete hain.

Ek pathreele headland (samundar mein niklti zameen) ko hazaaron saalon tak follow karo (Fig. 2.10). Sand aur pattharon se lais waves uske sire ke paas ek kamzor jod dhoondhti hain aur use khokhla karke sea cave bana deti hain. Jab dono taraf se khokhla hote-hote woh aar-paar khul jaata hai, to headland mein sea arch ban jaata hai. Ek din arch ki chhat gir jaati hai, aur samundar wala sira ek akele sea stack ki tarah bach jaata hai. Is beech main headland kat kar ek teekhi sea cliff ban jaata hai, jaise Kerala mein Varkala ki laal cliffs. Peeche chhoota samtal pathreela farsh, jise har tide dhota hai, wave-cut platform hai.

Yeh features tourists ko kheenchte hain: Andaman Islands mein Shaheed Dweep par Natural Bridge naam ka rock arch ek example hai. Saath hi, girti cliffs aur sikudte beaches coastal roads aur gaanvon ke liye khatra hain, isliye coast ke kuch hisson ko bachaav ke liye sea walls, tetrapods ya lagaaye gaye mangroves ki zaroorat hoti hai.

2.3.3 Glaciers

Glacier barf ki ek nadi hai jo din mein kuch centimetre se kuch metre tak dhalaan se neeche sarakti hai. Apne bed se jami hui, yeh rock ke tukde ukhaad leti hai aur unhe sandpaper ki tarah use karke zameen ko ghisti hai. Glacial erosion yeh landforms banata hai (Fig. 2.11):

• U-shaped valley: ek puraani river valley jise barf ne khod kar chauda trough bana diya hai, jiska farsh samtal aur sides cliff jaisi hain.
• Cirque: pahaad ki dhalaan par oonchaai par armchair jaisa gaddha jahan glacier shuru hota hai; barf pighalne ke baad ismein aksar ek chhoti jheel hoti hai jise tarn kehte hain.
• Arête: jab do cirques ek hi pahaad ko ulti taraf se khaate hain, to unke beech sirf rock ki ek patli, nukeeli deewar bachti hai.
• Hanging valley: kisi chhote side glacier ki valley, jo gehri hui main valley se bahut upar latki reh jaati hai, aur aksar uske muhaane se ek waterfall girta hai.
• Fjord: glacial valley jo barf pighalne ke baad samundar mein doob jaati hai, aur samundar ki ek lambi, teekhi deewaron wali baanh ban jaati hai, jaise Norway aur New Zealand mein.

Glacier ko malbe se ladi ek dheemi conveyor belt ki tarah socho: rock, sand aur clay, jinhe milakar till kehte hain. Jahan bhi yeh apna load girata hai, wahan moraines (हिमोढ़) chhod jaata hai (Fig. 2.12). Valley ki deewaron se girta malba barf ke har kinaare ke saath ridges mein jama hota hai: yeh lateral moraines hain. Jab do glaciers milte hain, to unke chhoote hue kinaaron ki ridges ek saath beech mein ek medial moraine ban kar aage chalti hain. Aage ki taraf, jahan barf utni hi tezi se pighalti hai jitni tezi se aage badhti hai, belt sab kuch ek mudi hui terminal moraine mein gira deti hai. Barf ke jaane ke bahut baad bhi yeh dikhati hai ki glacier kabhi kahan tak pahuncha tha.

Glaciers India ke jame hue water banks hain: Gangotri glacier, jahan se Gaumukh par Bhagirathi nikalti hai, monsoon se pehle ke sookhe mahinon mein nadiyon ko behta rakhta hai. Pahaadon mein gaanv, baag aur khet puraani glacial valleys ke chaude farsh par phaile hain, aur moraines ke peeche ruki jheelein paani aur kabhi-kabhi bijli deti hain. Trekkers, climbers aur skiers cirques aur glacial valleys ki taraf kheenche chale aate hain, aur Norway mein jahaaz gehre, shaant fjords mein panaah lete hain.

2.3.4 Wind

Deserts mein, jahan zameen ko pakadne ke liye paani ya paudhe kam hote hain, wind sabse bada moortikaar ban jaati hai. Yeh dheeli dhool aur sand uthaati hai aur daanon ko sandblaster ki tarah rock par phenkti hai. Wind erosion yeh landforms banata hai (Fig. 2.13):

• Yardangs: ulti naav jaisi rock ridges, jo hawa ki taraf wale sire par bhothari aur hawa ki disha mein patli hoti jaati hain; unke aas-paas ki naram rock ghis kar hat chuki hai.
• Ventifacts: kankad aur bade patthar jinki hawa ki taraf wali sides udte sand ne ghis kar chikni aur sapaat kar di hain.
• Deflation hollows (blowouts): zameen mein gaddhe jo hawa ke dheeli sand aur dhool uda le jaane ke baad bachte hain. Agar koi gaddha water table tak gehra ho jaaye, to paani rista hai aur ek oasis ban jaata hai.
• Desert pavements: hawa baareek daane uda le jaati hai, aur jo kankad itne bhaari hain ki hil na sakein, woh ek kasi hui, sapaat layer mein jam jaate hain.

Jahan hawa dheemi hoti hai, wahan woh apni sand ko teelon aur ridges mein gira deti hai jinhe sand dunes kehte hain. Unki shape is par nirbhar karti hai ki sand kitni hai aur hawa kitni sthir hai (Fig. 2.14).

• Barchan dunes: naye chaand jaisi shape, jinke seeng hawa ki disha mein hote hain. Yeh wahan milte hain jahan sand zyada nahi hoti aur hawa ek hi disha mein chalti hai, jaise Thar ke kuch hisson mein.
• Longitudinal dunes: sand ki patli ridges jo kilometres tak hawa ki hi disha mein chalti hain.
• Star dunes: oonche dher jinki baahein kai taraf phaili hoti hain, kyunki hawa baar-baar disha badalti hai.
• Parabolic dunes: U ki tarah mude hue, jinki baahein hawa ki ulti taraf peeche rehti hain aur ghaas ya jhaadiyon se tiki hoti hain; sandy beaches ke peeche aam hain.

Desert mein paani tay karta hai ki log kahan rahenge: oases kheti, aaraam aur vyapaar ke hare islands ban jaate hain. Ghaas ya jhaadiyon se dhaka dune chalna band kar deta hai, aur aise dunes ki ek belt desert ko kheton ki taraf badhne se dheema karti hai. Coast ke saath dunes samundari hawa aur storm waves ki taakat ko gaanvon tak pahunchne se pehle tod dete hain. Tourists Jaisalmer ke paas Sam ke dunes mein oont ki sawaari karte hain aur camp lagaate hain, aur builders kabhi-kabhi apne kaam ke liye dune ki sand khodte hain.

2.3.5 Zameen ke neeche ka paani

Zameen mein samaane wala baarish ka paani nazar se door bhi kaam karta rehta hai. Limestone mein yeh khaas taur par taakatwar hai, kyunki thoda acidic paani daraaron ke saath rock ko dheere-dheere gholta hai. Iska nateeja hai karst topography, jiska naam Slovenia aur Italy ki border par Kras region ke naam par hai (Fig. 2.15).

• Caves: zameen ke neeche kamre aur raaste, kuch itne bade ki unmein ek building aa jaaye, jo wahan bachte hain jahan limestone ghul gaya ho.
• Stalactites: cave ki chhat se neeche latakte chune ke stambh, jo boond-boond se bante hain jab chhat se rista paani peeche chune ka thoda sa nishaan chhod deta hai.
• Stalagmites: cave ke farsh se upar badhte chune ke stambh, jahan boondein girti hain. Jab ek stalactite aur ek stalagmite badh kar mil jaate hain, to pillar banta hai.
• Sinkholes (dolines): surface par keep jaise gaddhe, jahan neeche ki rock ghul gayi ho ya cave ki chhat dhans gayi ho.
• Underground rivers: naale jo zameen mein gaayab ho jaate hain aur cave ke raaston se behte hain, kabhi-kabhi kai kilometres tak.

Karst ilaaka logon ke liye maayne rakhta hai. Iske jharne aur underground streams meethe paani ke keemti source hain. Andhra Pradesh ki Borra Caves aur Meghalaya ke lambe cave systems jaisi caves tourists, cavers aur geologists ko kheenchti hain. Kuch caves pooja ki jagahein hain. Jammu and Kashmir ki Amarnath cave mein teerthyaatri farsh se uthte barf ke ek stambh ki pooja karte hain: yeh jame hue paani ka stalagmite hai.

2.4 Landforms aur disasters

Zyaadatar landforms itne dheere badalte hain ki kisi ko pata hi nahi chalta. Lekin kabhi-kabhi badlaav minuton mein aata hai: pahaadi khisak jaati hai, barf ki slope toot jaati hai, pahaadi jheel phat jaati hai, ya dhool ki deewar poore town ko nigal leti hai. Inmein se har hazard ek khaas tarah ke landform se juda hai, isliye zameen ko samajhna hamein yeh andaaza lagaane mein madad karta hai ki yeh kahan aa sakte hain aur kaise taiyaari karein. Hazard tab disaster banta hai jab woh aise logon par girta hai jo uske raaste mein hain aur taiyaar nahi hain.

2.4.1 Landslides

Landslide mein rock, soil aur malba achaanak slope se neeche khisak jaata hai. Slope tab tak apni jagah tiki rehti hai jab tak use pakadne wala friction use neeche kheenchne wali gravity se zyada taakatwar ho. Jo bhi cheez wazan badhaaye ya yeh pakad kam kare, woh santulan bigaad sakti hai.

• Zyada wazan, kam pakad: kai din ki tez baarish soil aur daraar wali rock mein samaa jaati hai, jisse slope bhaari aur andar se phisalan wali ho jaati hai. Band naaliyon mein ruka paani aur buildings ka bojh bhaar ko aur badhaate hain.
• Kam sahaara: road cuts, quarries aur mines, aur slope ke pair ko kaatti nadiyaan woh cheez hata deti hain jo use thaame rakhti hai; jungle kaatne se woh jadein hat jaati hain jo soil ko baandh kar rakhti hain.
• Achaanak jhatka: earthquakes, volcanic eruptions aur tez blasting bhi pehle se kamzor slope ko hila kar dheela kar sakte hain.
• Khatra sabse zyada un teekhi slopes par hai jo tooti hui ya gehraai tak gali hui rock se bani hon.

• Prone areas: Himalaya (Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, Darjeeling hills), North-East ke pahaad, aur Western Ghats aur Nilgiris (Kerala, Karnataka, Goa, Maharashtra, Tamil Nadu). Duniya bhar mein: teekhe, baarish wale regions jaise Andes, Nepal, Japan aur Philippines.
• Nuksaan kam karne ke tareeke: slopes ko risk ke hisaab se map karo aur sabse khatarnaak slopes par building mat banao; ped aur ghaas lagao; retaining walls aur sahi drains banao; jab baarish safe limit paar kare to warnings jaari karo.
• Example: 30 July 2024 ki subah-subah, bahut tez baarish ke baad, landslides ne Kerala ke Wayanad mein Mundakkai aur Chooralmala gaanvon ko dafna diya; 200 se zyada log maare gaye (state officials ke bataaye aankde, August 2024).

2.4.2 Avalanches

Avalanche barf ka ek bada dher hai, kabhi-kabhi barf ke tukdon aur rock ke saath mila hua, jo achaanak pahaad ki slope se tezi se neeche aata hai. Slope par barf layers mein jama hoti hai. Snowpack ko jhuke hue bistar par rakhe kambalon ke dher ki tarah socho: yeh tabhi tak tika rehta hai jab tak layers ke beech ka friction gravity ke kheenchaav se zyada ho.

• Kaaran: bojh tab badhta hai jab ek-do din mein bhaari barf girti hai, ya jab hawa kisi ridge ki ek taraf gehre dher jama kar deti hai. Layers ke beech ki pakad tab tootti hai jab pack mein koi kamzor, cheeni jaisi daanedaar layer dabi ho, ya jab garmi ke kuch din kuch barf ko gile keechad mein badal dein. Phir ek chhota jhatka, jaise earthquake, blast, skier, trekking party ya construction ka kaam, slab ko khiskaa sakta hai.
• Prone areas: Jammu and Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim aur Arunachal Pradesh ki oonchi slopes; duniya bhar mein Alps, Rockies aur Himalaya.
• Nuksaan kam karne ke tareeke: avalanche forecasts aur warnings; jaane-maane avalanche raaston par snow fences aur barriers; slopes par jungle; roads aur camps ko avalanche raaston se door rakhna aur bhaari barfbaari ke turant baad safar na karna.
• Example: 4 October 2022 ko Uttarakhand ke Uttarkashi district mein Draupadi ka Danda-II peak par ek avalanche mountaineering training team ko baha le gaya; 25 se zyada trainees aur instructors ki maut hui.

2.4.3 Glacial lake outburst floods

Jab glaciers peeche hatte hain, to pighla paani aksar aisi jheelon mein jama hota hai jinhe barf ya dheele moraine ka natural dam roke rakhta hai. Aisa dam tikne ke liye nahi bana hota. Agar woh toot jaaye, to jheel kuch hi ghanton mein khaali ho sakti hai, aur ek glacial lake outburst flood (हिमनद झील विस्फोट बाढ़) garajta hua valley mein neeche aata hai (Fig. 2.17).

• Kaaran: garam hote climate mein glaciers sikudte hain aur unki jheelein gehri hoti hain, isliye dheele moraine dams ko zyada se zyada paani rokna padta hai. Cloudburst ya tez pighlaav jheel ko achaanak bhar sakta hai. Aur bura yeh ki glacier ka koi tukda, avalanche ya landslide jheel mein gir kar ek wave bahar dhakel sakta hai, aur earthquake khud dam mein daraar daal sakta hai.
• Prone areas: Sikkim, Himachal Pradesh, Uttarakhand, Ladakh aur Arunachal Pradesh ki glacial lakes; saath hi Nepal, Bhutan, Pakistan aur Andes.
• Nuksaan kam karne ke tareeke: satellites aur sensors se glacial lakes par nazar rakhna; neeche ki valleys mein sirens aur warning systems; khatarnaak jheelon ka kuch paani pipes ya channels se nikaal kar unka level kam karna; gharon, roads aur dams ko baadh ke raaste se door rakhna.
• Example: 3–4 October 2023 ki raat north Sikkim ki South Lhonak Lake phat gayi; Teesta mein aayi baadh ne ek bade hydroelectric project ka Chungthang dam aur neeche ke bridges aur towns tabaah kar diye, aur kai log maare gaye ya laapata ho gaye.

2.4.4 Dust storms

Dust storm mein tez hawaayein itni sookhi soil aur sand utha leti hain ki aasmaan bhoora ho jaata hai aur shaayad kuch metre se aage dikhe bhi nahi. North-west India mein aise toofaan aksar monsoon se pehle ke garam mahinon mein aate hain, kabhi-kabhi garaj aur bijli ke saath.

• Kaaran: hawa ko uthaane ke liye dheela, sookha material chahiye. Mahinon bina baarish ke topsoil sookh kar dhool ban jaati hai; fasal ke baad nange chhode gaye khet, zarurat se zyada chare gaye charaagaah aur kate hue ped use rokne ke liye kuch nahi chhodte; aur garmi ke thunderstorm se pehle aane wale hawa ke jhonke bahut tez ho sakte hain. Scientists ka andaaza hai ki garam climate aisi aur extreme ghatnaayein laayega.
• Prone areas: Rajasthan, Punjab, Haryana, western Uttar Pradesh aur Delhi; duniya bhar mein Sahara, West Asia, Central Asia aur Gobi.
• Nuksaan kam karne ke tareeke: shelterbelts ke roop mein pedon ki kataarein; ghaas jo sand dunes ko apni jagah rokti hai; zarurat se zyada charaai par control; weather warnings, taaki log ghar ke andar rahein aur kamzor deewaron, pedon aur bijli ke poles se door rahein.
• Example: 2–3 May 2018 ko Rajasthan aur Uttar Pradesh mein bhayankar dust storms aaye; 4 May tak authorities ne 100 se zyada maut gini, jinmein se kai girti deewaron, pedon aur poles se hui.

Thoda peeche hat kar dekho, to poora chapter ek rassa-kashi ban jaata hai. Ek taraf Earth ki andar ki garmi plates ko chalati hai, rock ko modti aur todti hai, aur lava bahaati hai: mountains, rift valleys, ridges aur trenches iska kaam hain. Doosri taraf Sun ki energy aur gravity paani, barf, wind aur waves ko chalati hain, jo oonchaaiyon ko ghis dete hain aur malbe ko plains, deltas, dunes aur beaches ke roop mein phaila dete hain. Har khet, town, road aur teerth ka raasta isi nateeje par tika hai. Yeh jaanna ki zameen kaise bani, aur woh kitni achaanak khisak sakti hai, uska samajhdaari se use karne aur us par surakshit rehne ka pehla kadam hai.