Ubudala bomhlaba

Ubuncinane okwangoku, iplanethi kuphela apho kukho ubomi. Umgama nje ofanelekileyo ukusuka elangeni ukuze kubekho amanzi ngendlela engamanzi kunye neqondo lobushushu elanele ngokwaneleyo ukuba likhule izigidi zezityalo nezilwanyana. Umhlaba.

Ingaba umngakanani? Uhambo lwakhe lokuba yile nto ayiyo namhlanje lude kwaye luyingozi. Isithuba esingaphandle asiyondawo ikhuselekileyo. Kodwa, Yintoni ubudala bomhlaba kwaye ubalwe njani?

Mdala kangakanani uMhlaba?

Nangona kungekho nani lichanekileyo, Iplanethi yethu yaziwa ukuba ineminyaka emalunga neebhiliyoni ezi-4.500 ubudala. Izazi ngokuma komhlaba kunye nejogophysics ziye zakwazi ukubala iminyaka ngokulinganisa inqanaba apho izinto ze-uranium yentsimbi ebola ibola. Ngokusebenzisa ubuchwephetsha bokuthandana, bafumene ubudala beemeteorite, ezifanayo kumhlaba naseNyangeni.

Eyona minerali indala yaziwa ngokuba yi-zirconium evela kwingingqi yeJack Hills eNtshona Australia. Baqikelelwa ukuba babe zizigidi ezingama-4.404 ubudala. Ama-meteorite amadala afunyenwe kwinkqubo yelanga, oko kukuthi, i-calcium inclusion-rich inclusions, aneminyaka engama-4.567 yezigidi ubudala. Oku kuthetha ukuba i-Solar System yaqala ukwenza i-4.567 yezigidi zeminyaka eyadlulayo.

Olunye uluvo lokuba uMhlaba waqala ukubumba kwakamsinya emva kokuba imeteorite yenzile, kodwa akukabikho mfuneko yokwalatha ubudala bayo ngqo.

Iithiyori zokuqala

Kangangexesha elide bekucingelwa ukuba iplanethi ibilapha ngonaphakade, de izazi zendalo zaqala ukuqonda utshintsho olwahlukileyo olwenziwe yiplanethi ngokufunda ubume bayo. UNicolas Steno wayengomnye wabokuqala ukuqonda unxibelelwano phakathi kwentsalela yefosili kunye nolu luhlu sele lukhankanyiwe. Malunga ne-1790, isazi sendalo sase-Bhritane u-William Smith waqikelela ukuba ukuba ngamatye amabini kwiindawo ezahlukeneyo aqulathe amathambo afanayo, bekuyinto entle ukuba omabini la maleko avela ngexesha elinye. Kwiminyaka kamva umtshana wakhe, uJohn Phillips, wabala esebenzisa obu buchule ukuba ubudala boMhlaba buya kuba malunga neminyaka engama-96 ezigidi.

Ingcali yendalo uMikhail Lomonosov wayecinga ukuba uMhlaba ubuzimele ngaphandle kwendalo iphela, kumakhulu amawaka eminyaka eyadlulayo. Ngo-1779 isazi sendalo esingumFrentshi uComte Du Buffon wenza ulingelo: wenza iglobhu encinci enombhalo ofana nqwa nomhlaba, emva koko walinganisa ukuphola kwawo. Ke, uqikelele ubudala bomhlaba kwiminyaka engama-75 amawaka.

Nangona kunjalo, Kwakungekho ngo-1830 ukuba i-geologist egama linguCharles Lyell iphakamise ukuba iplanethi ihlala iguquka. Oku, nangona namhlanje kuyinto yendalo kwaye isengqiqweni ngokupheleleyo kuthi, ngelo xesha yayiyithiyori yenoveli, kuba babecinga ukuba iplanethi iyinto emileyo, ukuba itshintshe kuphela ngenxa yeentlekele zendalo.

Ukubala

Umzimba we IGlasgow William Thomson yapapashwa ngo-1862 uthotho lwezibalo eziqikelela ukuba ubudala beplanethi yethu buphakathi kwezigidi ezingama-24 nama-400 ezigidi zeminyaka. U-Lord Kelvin, owayezakubizwa kanjalo emva koko, wayecinga ukuba uMhlaba ubunjwe njengebhola yedwala elinyibilikisiweyo, kwaye wabala ixesha elithathiweyo kwinkqubo yokupholisa ukufikelela kubushushu obuphakathi (14 ° C). Ngaphandle kwayo yonke into, iijoloji zazingaqinisekanga ncam ukuba le hypothesis yayisemthethweni.

UCharles Darwin, owayefunda imisebenzi kaLyell, wacebisa ithiyori yakhe yokhetho lwendalo, inkqubo apho uthotho lotshintsho kwizinto eziphilayo kwaye, ewe, ixesha lalifuneka ukuze zenzeke.. Ke ngoko, wayecinga ukuba iminyaka eyi-400 yezigidi ayonelanga.

Ngo-1856 ugqirha wamachiza waseJamani uHermann von Helmholt kwaye ngo-1892 isazi ngeenkwenkwezi saseKhanada uSimon Newcomb, wazibalisela ezabo izibalo. Eyokuqala yayineminyaka engama-22 yezigidi ubudala, kwaye eyesibini ili-18 lezigidi. Izazinzulu zifikile kula manani ngokubala ixesha ebeliza kulithatha ukuze iLanga liguquke liye kububanzi balo ngoku kunye nobunzulu ukusuka kwi-nebula yegesi kunye nothuli olwenziwe kulo.

Ukuphuhliswa kokuthandana kwe-radiometric

Namhlanje sinokufumana umbono wokuba amadala kunye neeminerali ezindala zibulela njani ukuthandana kwe-radiometric, ethi Yinkqubo eyaphuhliswa ngu-Arthur Holmes ekuqaleni kwenkulungwane yama-XNUMX kwaye esekwe kubungakanani besotopope ebizwa ngokuba ngutata kunye nesinye okanye inzala engaphezulu kwesiqingatha sobomi baziwa.

Ukuthandana kweRadiometric kwapapashwa okokuqala ngo-1907 nguBertran Boltwood kwaye namhlanje ingoyena mthombo wolwazi malunga nobudala bamatye, okanye iplanethi yoMhlaba uqobo. Kukho iindlela ezahlukeneyo zokuthandana, ezi zezi:

• Indlela yeCarbon 14: Iluncedo ekuboniseni inzululwazi ngezinto zakudala, i-anthropology, iklimatology, i-oceanography, isayensi yomhlaba kunye nejoloji yakutshanje.
• Indlela yePotassium-argon: isetyenziswe kwi-geology.
• Indlela yeRubidium-etrontium: isetyenziselwa ukuthandana kwamatye asemhlabeni akudala kunye ne-miestras yenyanga.
• Thorium 230 iindlela: esetyenziswa kwi-sediment yolwandle endala kakhulu ukuthandana.
• Iindlela zokukhokela: isetyenziswe kwi-geology.

Ngaloo ndlela, UHolmes wenza imilinganiselo kwiisampulu zelitye kwaye ngo-1911 wagqiba kwelokuba oyena mdala wayeneminyaka eyi-1600 yezigidi ubudala.. Kodwa ezi zibalo zazingathembakali. Kwiminyaka emibini kamva, kwapapashwa iziphumo ezibonisa ukuba izinto zazineesotopu, ezahlukileyo ngeendlela ezahlukeneyo. Ngama-30, ii-isotop zaboniswa ukuba zineenuclei ezenziwe ngamanani ahlukeneyo amaqhekeza angathathi hlangothi okanye i-neutron.

Umsebenzi kaHolmes wahoywa de kwaba li-1920s, xa ngo-1921 kwintlanganiso yaminyaka le yoMbutho WaseBritane Wokuqhubela Phambili Kwenzululwazi amalungu aqinisekisa ukuba iminyaka yeplanethi yayiyiminyaka yeebhiliyoni ezimbalwa, kwanokuba ukuthandana kwe-radiometric kwakuthembekile. Ngo-1927 wapapasha umsebenzi wakhe »The Age of the Earth, i-Introduction to Geological Ideas apho wabala khona ukuba yayiphakathi kweminyaka eyi-1600 kunye ne-3000 yezigidi ubudala.

Malunga no-1931 iNational Reserach Council, ye-National Academy of Science yase-United States, yonyula ikomiti eyakufumanisa ukuba uMhlaba mdala kangakanani. UHolmes, ongomnye wabantu abambalwa ababezazi iindlela zokuthandana nge-radiometric, wamenywa ukuba asebenze kwikomiti. Ingxelo abayivelisileyo yathi ukuthandana kwe-radiometric kuphela kwendlela enokuthenjwa enokusetyenziselwa ukumisela ukulandelelana kwamaxesha e-geologic.

Okokugqibela, i-CC Patterson yabala ubudala boMhlaba ngo-1956 isebenzisa isotopu yokuthandana kwe-uranium ekhokelela ekubolekeni kweetyathanga zeemeteorites.

Iplanethi yethu isenezigidi ezininzi zeminyaka yobomi phambi kwayo. Ukuba ekugqibeleni ithiyori yokuba iLanga "liya kuwuginya" umhlaba xa ujika waba yingxilimbela ebomvu, sinokuqiniseka ukuba isazakujikeleza inkosi yenkwenkwezi malunga neebhiliyoni ezintlanu zeminyaka.