Okungenani okwamanje, ukuphela kweplanethi okukhona kuyo impilo. Kuyinto nje ibanga elifanele ukusuka elangeni ukuze kube namanzi asesimweni soketshezi kanye nezinga lokushisa elanele ngokwanele ukuba likhule izigidi zezitshalo nezilwane. Umhlaba.
Uneminyaka emingaka? Uhambo lwakhe lokuba yilokhu ayikho manje belulude kakhulu futhi lugcwele ingozi. Isikhala esingaphandle akuyona indawo ephephile. Kepha, Uyini umhlaba womhlaba futhi ubalwe kanjani?
Uneminyaka emingaki uMhlaba?
Noma ingekho inombolo eqondile, iplanethi yethu yaziwa cishe ineminyaka eyizigidi eziyizinkulungwane ezine nengxenye ubudala. Izazi zokuma komhlaba nezazi ze-geophysicist ziye zakwazi ukubala iminyaka ngokukala izinga izakhi ze-uranium yensimbi ekhipha imisebe ezibola ngayo zibe umthofu. Futhi, besebenzisa amasu okuthandana nge-radiometric, baye banquma iminyaka yama-meteorite, efana neyoMhlaba neNyanga.
Amaminerali amadala kakhulu aziwayo yi-zirconium evela endaweni yaseJack Hills eNtshonalanga Australia. Kulinganiselwa ukuthi baneminyaka engama-4.404 wezigidi ubudala. Ama-meteorite amadala kakhulu atholakala kusistimu yelanga, okungukuthi, ukufakwa kwe-calcium-aluminium-rich, aneminyaka eyizigidi ezingama-4.567. Lokhu kusho ukuthi I-Solar System yaqala ukwakha eminyakeni eyizigidi eziyizinkulungwane ezingu-4.567 edlule.
I-hypothesis eyodwa ithi uMhlaba waqala ukwakheka ngemuva nje kokuthi ama-meteorite enzile, kepha okwamanje akukwazi ukukhomba ubudala bawo ngqo.
Imibono yokuqala
Isikhathi eside bekucatshangwa ukuthi iplanethi ibilokhu ikhona kuze kube phakade, kuze kube yilapho izazi zemvelo ziqala ukuqonda izinguquko ezahlukahlukene iplanethi eyazenza lapho zihlola izingqimba zayo. U-Nicolas Steno ube ngomunye wabokuqala ababona ukuxhumana phakathi kwezinsalela zezinsalela kanye ne-strata eshiwo ngenhla. Cishe ngo-1790, isazi semvelo saseBrithani uWilliam Smith sacabanga ukuthi uma izingqimba ezimbili zamadwala ezitholakala ezindaweni ezihlukene zinezinsalela ezifanayo, kungenzeka ukuthi zombili izingqimba zavela enkathini efanayo. Ngemva kweminyaka, umshana wakhe, uJohn Phillips, wabala esebenzisa lezi zindlela ukuthi iminyaka yoMhlaba yayingaba yiminyaka eyizigidi ezingu-96.
Isazi semvelo uMikhail Lomonosov wacabanga ukuthi uMhlaba wakha ngokuzimela kuwo wonke umhlaba, eminyakeni eyizinkulungwane ezingamakhulu ambalwa edlule. Ngo-1779, isazi semvelo saseFrance u-Comte Du Buffon senza isilingo: wakha imbulunga encane ukwakheka kwayo kwakufana neplanethi yase ikala izinga lokupholisa kwayo. Ngakho, walinganisela ubudala bomhlaba cishe eminyakeni eyizinkulungwane ezingu-75.
Nokho, Kwaze kwaba ngo-1830 lapho isazi sokuma komhlaba okuthiwa uCharles Lyell sasikisela ukuthi iplanethi ishintsha njalo. Nakuba lokhu kungase kubonakale kungokwemvelo futhi kunengqondo ngokuphelele kithi namuhla, ngaleso sikhathi kwakuyinkolelo-mbono entsha kakhulu, ngoba babecabanga ukuthi iplanethi yinto emile, eyashintsha kuphela ngezinhlekelele zemvelo.
Izibalo
Umzimba we Ngo-1862, uWilliam Thomson waseGlasgow washicilela uchungechunge lwezibalo olwalinganisela ubudala bomhlaba wethu ukuba bube phakathi kwezigidi ezingu-24 nezingu-400 zeminyaka. U-Lord Kelvin, njengoba ayezobizwa kanjalo kamuva, wathatha ngokuthi uMhlaba wakheka njengebhola letshe elincibilikisiwe, futhi wabala isikhathi esisithathayo ukuze inqubo yokupholisa ifinyelele izinga lokushisa elivamile lamanje (14ºC). Naphezu kwakho konke, izazi zokuma komhlaba zazingaqinisekanga ngokuphelele ukuthi le nkolelo-mbono yayiyiqiniso.
UCharles Darwin, owafunda izincwadi zikaLyell, waphakamisa inkolelo-mbono yakhe yokuzikhethela kwemvelo, inqubo okwakudingeka ngayo uchungechunge lwezinguquko ezintweni eziphilayo futhi, yiqiniso, isikhathi sokuba zenzeke. Ngakho-ke, wacabanga ukuthi iminyaka eyizigidi ezingu-400 kwakuyinkathi eyanele.
Ngo-1856, isazi sesayensi yesayensi yemvelo saseJalimane uHermann von Helmholt futhi ngo-1892, isazi sezinkanyezi saseCanada uSimon Newcomb banikeza izibalo zabo siqu. Eyokuqala yayineminyaka eyizigidi ezingu-22 ubudala, kanti eyesibili yayineminyaka eyizigidi ezingu-18 ubudala. Ososayensi babefike kulezi zibalo ngokubala isikhathi elalizosithatha ukuze iLanga liguquke ukuze lifinyelele ububanzi nobukhulu balo bamanje lisuka ku-nebula yegesi nothuli elakheka ngalo.
Ukuthuthukiswa kokuphola nge-radiometric
Njengamanje singaba nomqondo wokuthi amadwala namaminerali amadala kangakanani ngenxa yokuphola nge-radiometric, okuyi Kuyinqubo eyasungulwa ngu-Arthur Holmes ekuqaleni kwekhulu lama-20 futhi isekelwe esilinganisweni se-isotope ebizwa ngokuthi umzali kanye nenzalo eyodwa noma ngaphezulu ohafu-mpilo wabo owaziwayo.
Ukuqomisana kweRadiometric kwashicilelwa okokuqala ngonyaka we-1907 nguBertran Boltwood futhi namuhla kungumthombo omkhulu wolwazi mayelana neminyaka yamatshe, noma iplanethi yoMhlaba uqobo. Kunezindlela ezahlukahlukene zokuqomisana, okuyilezi:
- Indlela yeCarbon 14: Ilusizo ekuqomeni kwezemivubukulo, i-anthropology, i-climatology, i-oceanography, i-edaphology, ne-geology yakamuva.
- Indlela ye-Potassium-argon: isetshenziswa ku-geology.
- Indlela yeRubidium-etrontium: Isetshenziswa ekuqomeni amatshe asendulo asemhlabeni kanye namasampula enyanga.
- Izindlela zeThorium 230: esetshenziswa ezindlekweni zasolwandle ezindala kakhulu.
- Izindlela zokuhola: isetshenziswe ku-geology.
Ngakho, U-Holmes wenza izilinganiso kumasampula edwala futhi ngo-1911 waphetha ngokuthi endala yayineminyaka eyizigidi eziyizinkulungwane ezingu-1600 ubudala. Kodwa lezi zibalo zazingethembekile kakhulu. Eminyakeni emibili kamuva, imiphumela yashicilelwa ebonisa ukuthi ama-elementi anama-isotopes, okuyizinhlobonhlobo ezihlukene ezinobuningi obuhlukahlukene. Ngawo-30, kwaboniswa ukuthi ama-isotopes ane-nuclei eyakhiwe izinombolo ezihlukene zezinhlayiya ezingathathi hlangothi noma ama-neutron.
Umsebenzi kaHolmes wazitshwa kwaze kwaba ngawo-1920, lapho Ngo-1921 emhlanganweni waminyaka yonke we-British Association for the Advancement of Science, amalungu asungula ukuthi iminyaka yeplanethi yayiyiminyaka eyizigidi eziyizinkulungwane ezimbalwa, nokuthi ukuphola kwe-radiometric kwakuthembekile. Ngo-1927 washicilela incwadi yakhe ethi "The Age of the Earth, an Introduction to Geological Ideas lapho alinganisela khona ukuthi yayiphakathi kweminyaka eyi-1600 ne-3000 yezigidi ubudala.
Cishe ngo-1931, uMkhandlu Kazwelonke Wokucwaninga we-United States National Academy of Sciences waqoka ikomidi elizonquma ubudala boMhlaba. UHolmes, engomunye wabantu abambalwa abajwayelene namasu okuqomisana nge-radiometric, wamenywa ukuthi ajoyine ikomidi. Umbiko abawukhiqizayo wathi ukujola kwe-radiometric kwakuwukuphela kwendlela enokwethenjelwa engasetshenziswa ukuthola ukulandelana kwezikhathi ze-geologic.
Ekugcineni, u-CC Patterson wabala iminyaka yoMhlaba ngo-1956 esebenzisa i-isotope ye-uranium-lead decay chain of meteorites.
Iplanethi yethu isenezigidi eziningi zeminyaka yokuphila ngaphambi kwayo. Uma ekugcineni umbono wokuthi iLanga "lizogwinya" umhlaba lapho uphenduka umdondoshiya obomvu, singaqiniseka ukuthi usazungeza inkosi yenkanyezi cishe iminyaka eyizigidi eziyizinkulungwane ezinhlanu.
Kuyizinkolelo nje kuphela, kusaziwa ngokusobala ukuthi ngabe lolu lwazi luyiqiniso. Kepha yibo abasondelene neqiniso.
Isiphetho esibaluleke kunazo zonke besilahlekile, futhi lokho ukubalwa kweminyaka yomhlaba ngokusho kocwaningo lwakamuva olwenziwa yiCC Patterson ngo-1956 kusetshenziswa isotopu esivela ku-uranium lead lead chain of meteorites.