Iplanethi yethu yaphenduka yabheka phansi eminyakeni eyizigidi ezingu-84 edlule lapho ama-dinosaurs ehamba emhlabeni. Ngokuqondile, kwenzeka into ebizwa ngokuthi i-real pole shift, ekwazi ukuguqula ukuthambekela kwendikimba yasezulwini ngokuphathelene ne-axis yayo futhi ibangele "ukuzamazama". Kukhona ezinye izifundo eziqinisekisa lokho umhlaba ungagoqa eksisini yawo futhi lokhu kungabangela izinkinga ezinkulu esintwini kanye nempilo njengoba sikwazi.
Ngalesi sizathu, sizonikezela lesi sihloko ukuze sikutshele ukuthi umhlaba ungavula kanjani i-eksisi yawo nokuthi ungaba namiphi imiphumela.
Umhlaba ungagoqa eksisini yawo
Ukushintsha kwezigxobo kwangempela kwenzeka lapho izigxobo zomhlaba ezisenyakatho naseningizimu zishintsha kakhulu, okubangela uqweqwe oluqinile ukuthi lujibele oqwembeni olungaphezulu oluwuketshezi oluvikela umongo. Akuzange kuthinteke insimu kazibuthe noma ukuphila eMhlabeni, kodwa idwala elisusiwe laqopha ukuphazamiseka ngendlela yedatha ye-paleomagnetic.
“Zicabange ubuka uMhlaba usemkhathini,” kuchaza uJoe Kirschvink, isazi sokuma komhlaba e-Tokyo Institute of Technology eJapane, kanye nomunye wababhali. "Iqiniso le-polar drift linikeza umbono wokuthi iplanethi inyakaza ohlangothini olulodwa, lapho empeleni okwenzekayo ukuthi indawo enamatshe (ingubo eqinile noqweqwe) izungeza ngaphezu kwengubo ewuketshezi futhi izungeze umgogodla ongaphandle" .
"Ama-rock amaningi aqopha umumo womkhakha kazibuthe wendawo njengoba akhiwa, okufana nendlela umculo oqoshiwe," kuchaza isitatimende esitatimendeni. Isibonelo, amakristalu amancane e-magnetite akha ama-magnetosomes asiza amagciwane ahlukahlukene ukuthi aziqondise futhi aqondanise ngokunembile nezigxobo kazibuthe. Njengoba amadwala eqina, avaleleka futhi akhe "izinaliti zekhampasi ezincane," okubonisa ukuthi isigxobo sasikuphi nokuthi sasihamba kanjani ngesikhathi seCretaceous sekwephuzile.
Futhi, leli rekhodi lamandla kazibuthe lisenza sazi ukuthi idwala liqhele kangakanani onqenqemeni: enyakatho nenkabazwe, uma lime mpo ngokuphelele, kusho ukuthi lisesigxotsheni, kuyilapho uma livundlile, lokho kulibeka enkabazwe. Ushintsho ekumiseni kwezendlalelo ezihambisana nenkathi efanayo lungabonisa ukuthi iplanethi "iyazamazama" ku-eksisi yayo.
Izifundo zokuthi umhlaba ungakwazi yini ukuthinta ku-eksisi yawo
Ukuze athole izimpawu zalesi simo, omunye umlobi, uProfesa Ross Mitchell we-Institute of Geology and Geophysics eBeijing, eChina, wakhumbula indawo ekahle ayihlaziya lapho esengumfundi. Leli yiChibi i-Apiro, ezintabeni zase-Apennine, enkabeni ye-Italy, lapho kwakhiwa khona itshe le-limestone ngaleso sikhathi ababenesithakazelo sokuphenya: phakathi kweminyaka eyizigidi ezi-1 nezingama-65,5 edlule, usuku okuqagelwe ngalo lokushabalala kwama-dinosaur.
Iqhutshwa umbono wangempela we-polar wander, idatha eqoqwe ku-limestone yase-Italy iphakamisa ukuthi Umhlaba utsheke cishe ama-degree angu-12 ngaphambi kokuzilungisa wona. Ngemva kokutshekisa, noma "ukuguquguquka", iplanethi yethu yashintsha indlela futhi ekugcineni yadweba i-arc ecishe ibe ngu-25°, ababhali bayichaza ngokuthi "i-offset egcwele" kanye "ne-cosmic yo-yo" ethatha iminyaka eyizigidi ezi-5.
Ucwaningo lwangaphambilini lwaphika ukuthi kungenzeka kube khona ukuzulazula kwe-polar kwangempela ekupheleni kwesikhathi se-Cretaceous, ukubheja ekuzinzeni kwe-eksisi Yomhlaba phakathi neminyaka eyizigidi eziyi-100 edlule, "ngaphandle kokuqoqa idatha eyanele evela kumarekhodi omhlaba," kuphawula ababhali baleli phepha. "Leso ngesinye sezizathu ezenza lolu cwaningo kanye nengcebo yalo yedatha enhle ye-paleomagnetic kuqabule," kusho isazi sesayensi yokwakheka komhlaba uRichard Gordon wase-Rice University e-Houston engeza kumazwana.
Incazelo yesayensi
Umhlaba uyindilinga enezingqimba onomgogodla oqinile wensimbi, umgogodla owuketshezi wensimbi, kanye nengubo eqinile noqweqwe olubusa indawo esihlala kuyo. Onke aphenduka njengesiqongo, kanye ngosuku. Ngoba Umnyombo wangaphandle womhlaba uwuketshezi, isiphuku esiqinile noqweqwe kungashelela phezu kwawo. Izakhiwo eziminyene uma kuqhathaniswa, njengokwehlisa amapuleti olwandle kanye nezintaba-mlilo ezinkulu ezifana nezaseHawaii, zincamela ukuba seduze nenkabazwe.
Naphezu kwalokhu kugudluzwa kwe-crustal, inkambu kazibuthe Yomhlaba ikhiqizwa imisinga ku-convective liquid metal Ni-Fe kunkambo yangaphandle. Ezikalini zesikhathi eside, ukunyakaza kwengubo noqweqwe olungaphezulu akuthinti umnyombo woMhlaba, ngoba lezo zingqimba zamatshe ezilele phezulu zisobala kumhlaba kazibuthe. Esikhundleni salokho, amaphethini e-convection kulo mnyombo wangaphandle aphoqeleka ukuthi adanse azungeze i-eksisi yokuzungeza yomhlaba, okusho ukuthi iphethini evamile yendawo kazibuthe yomhlaba iyabikezelwa, zisakazeka ngendlela efanayo naleyo amafayili ensimbi anqwabelana ngayo ezintini ezincane kazibuthe.
Ngakho-ke idatha inikeza ulwazi oluhle kakhulu mayelana nokuma kwendawo yezigxobo ezisenyakatho naseningizimu, futhi ukutsheka kunikeza ibanga ukusuka ezigxotsheni (inkundla eqondile isho ukuthi usezigxotsheni, indawo evundlile isho ukuthi usenkabazwe). Amadwala amaningi aqopha isiqondiso samandla kazibuthe wendawo njengoba akha, njengomculo oqoshiwe. Isibonelo, amakristalu amancane e-mineral magnetite akhiqizwa amanye amabhaktheriya empeleni ahambisana izinaliti zekhampasi ezincane futhi zivaleleke othulini njengoba idwala liqina. Le "fossil" kazibuthe ingasetshenziswa ukulandelela lapho i-eksisi yokuzungezisa isuke khona uma kuqhathaniswa noqweqwe loMhlaba.
“Cabanga ubuka uMhlaba usemkhathini,” kuchaza umlobi wocwaningo uJoe Kirschwenk weTokyo Institute of Technology, lapho i-ELSI izinze khona. "I-polar drift yangempela ibukeka sengathi uMhlaba utshekela ohlangothini olulodwa, lapho okwenzekayo ngempela igobolondo langaphandle elinamatshe lomhlaba (ingubo eqinile noqweqwe) elizungeza umnyombo wangaphandle owuketshezi." Ukukhukhuleka kweqiniso kwe-polar kwenzekile, kodwa Izazi zesayensi yokwakheka komhlaba ziyaqhubeka nokuphikisana ngokuthi ngabe ukuzungeza okukhulu kwengubo yoMhlaba noqweqwe lwenzeka yini esikhathini esidlule.
Ngethemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana nokuthi uMhlaba ungakwazi yini ukuvula i-eksisi yawo.