Isijikelezi-langa sethu saguqulelwa phantsi kwiminyaka eyi-84 yezigidi eyadlulayo xa iidayinaso zazihamba emhlabeni. Ngokuchanekileyo, into ebizwa ngokuba yi-real pole shift yenzeke, ekwazi ukutshintsha ukuthambekela komzimba wezulu ngokubhekiselele kwi-axis yayo kwaye ibangele "ukugungqa". Kukho izifundo ezithile ezingqina oko umhlaba unokuthe nca kwiaxis yawo kwaye oku kunokubangela iingxaki ezinzulu kuluntu kunye nobomi njengoko sisazi.
Ngesi sizathu, siza kunikezela eli nqaku ukukuxelela ukuba uMhlaba unokujika njani kwi-axis yawo kwaye zeziphi iziphumo onokuthi ube nazo.
Umhlaba unokuthe nca kwi-axis yawo
Ukutshintsha kwepali yokwenyani kwenzeka xa iipali zomhlaba ezisemantla nasezantsi zitshintsha ngokuphawulekayo, nto leyo ebangela ukuba uqweqwe oluqinileyo lujike lube kulwelo olungasentla olukhusela umbindi. Ayizange ichaphazeleke intsimi yamagnetic okanye ubomi emhlabeni, kodwa ilitye elisusiweyo labhala ukuphazamiseka ngendlela yedatha ye-paleomagnetic.
“Khawube nomfanekiso-ngqondweni wakho ujonge uMhlaba ukwisibhakabhaka,” uchaza uJoe Kirschvink, isazi senzululwazi ngokwakheka komhlaba kwiZiko leTekhnoloji laseTokyo eJapan, kunye nomnye wababhali. "Inyani yepolar drift inika umbono wokuba iplanethi ijongeka kwicala elinye, xa eyona nto yenzekayo kukuba umphezulu wamatye (ingubo eqinileyo kunye noqweqwe) ujikeleza ngaphezulu kwengubo yolwelo kwaye ujikeleze umbindi wangaphandle" .
"Amatye amaninzi abhala ukuqhelaniswa kwendawo yamagnetic yendawo njengoko ayenzile, efana nendlela yokurekhoda umculo," iziko lachaza kwingxelo. Ngokomzekelo, iikristale zemagnetite ezincinci ezizenzayo iimagnetosomes zinceda iibhaktheriya ezahlukahlukeneyo ukuba ziziqhelanise kwaye zilungelelanise ngokuchanekileyo nezibonda zemagnethi. Njengoko amatye aqina, abanjwa kwaye enza "iinaliti zekhampasi ezincinci," ebonisa ukuba yayiphi ipali kunye nendlela eyayihamba ngayo ngexesha leCretaceous.
Kwakhona, le ngxelo yamandla kazibuthe isenza sazi ukuba ilitye likude kangakanani na ukusuka emphethweni: kumntla we-hemisphere, ukuba uthe nkqo ngokugqibeleleyo, oko kuthetha ukuba kwipali, ngelixa lithe tye, elibeka kwi-ikhweyitha. Utshintsho kwi-orientation yeeleya ezihambelana nexesha elifanayo kuya kubonisa ukuba iplanethi "iyagubha" kwi-axis yayo.
Izifundo malunga nokuba umhlaba unako ukugoba kwi-axis yawo
Ukuze afumane iimpawu zesi siganeko, omnye umbhali, uNjingalwazi uRoss Mitchell weZiko leGeology and Geophysics eBeijing, eTshayina, wakhumbula indawo egqibeleleyo awayihlalutyayo xa wayengumfundi. Eli liChibi iApiro, kwiintaba zeApennine, kumbindi weItali, apho ilitye lekalika lenziwa kanye kanye ngelo xesha babenomdla wokuphanda: phakathi kwe-1 kunye ne-65,5 yezigidi zeminyaka eyadlulayo, umhla oqikelelweyo wokuphela kweedayinaso.
Iqhutywa yinyani yepolar wander hypothesis, idatha eqokelelwe kwi-limestone yase-Italiya icebisa ukuba uMhlaba uthambekele malunga ne-12 degrees ngaphambi kokuba uzilungise. Emva kokuthamba, okanye "ukuguqa", iplanethi yethu yatshintsha indlela kwaye ekugqibeleni yazoba i-arc ephantse ibe yi-25 °, ababhali bayichaza "njenge-fill offset" kunye ne "cosmic yo-yo" ehlala malunga nezigidi ezi-5 zeminyaka.
Uphando lwangaphambili lukhanyele ukuba kunokwenzeka ukuzulazula kwi-polar yokwenyani ekupheleni kwexesha le-Cretaceous, ukubheja kuzinzo lwe-axis yoMhlaba kwiminyaka eyi-100 yezigidi ezidlulileyo. "Ngaphandle kokuqokelela idatha eyaneleyo kwirekhodi yejoloji," ababhali bephepha baphawula. "Eso sesinye sezizathu ezibangela ukuba olu phononongo kunye nobutyebi bayo bedatha entle ye-paleomagnetic ihlaziye kakhulu," isazi se-geophysicist uRichard Gordon weYunivesithi yaseRice eHouston yongeza kwizimvo.
Ingcaciso yenzululwazi
Umhlaba yingqukuva enemaleko kunye nombindi wesinyithi oqinileyo ongaphakathi, umbindi wentsimbi engamanzi, kunye nengubo eqinileyo kunye noqweqwe olulawula umphezulu esihlala kuwo. Zonke zijikeleza njengomphezulu, kanye ngemini. Ngokuba Umbindi womhlaba wangaphandle ululwelo, ingubo eqinileyo kunye noqweqwe lunokutyibilika phezu kwawo. Izakhiwo ezixineneyo ngokwentelekiso, ezifana nokuthoba iipleyiti zolwandle kunye neentaba-mlilo ezinkulu njengeHawaii, zikhetha ukuba kufutshane ne-ikhweyitha.
Ngaphandle koku kufuduswa kwe-crustal, umhlaba wemagnethi womhlaba uveliswa yimisinga kwi-convective liquid metal Ni-Fe kumbindi wangaphandle. Kwizikali zexesha elide, ukuhamba kwengubo kunye noqweqwe olungaphezulu akuchaphazeli umbindi woMhlaba, kuba ezo maleko angaphezulu amatye abonakala elubala kumhlaba womhlaba. Endaweni yoko, iipateni zeconvection kulo mbindi wangaphandle zinyanzelwa ukuba zidane zijikeleze i-axis yomhlaba yokujikeleza, okuthetha ukuba ipateni ngokubanzi yomhlaba wemagnethi woMhlaba unokuqikelelwa, zisasazeke ngendlela efanayo ukuba iifayili zentsimbi zikrola kwiintonga ezincinci zemagneti.
Ke idatha inika ulwazi olugqwesileyo malunga nokujongwa kwejografi kwiipali ezisemantla nakumazantsi, kwaye ukuthambeka kunika umgama ukusuka kwiipali (ibala elithe nkqo lithetha ukuba ukwipali, indawo ethe tye ithetha ukuba uku-ikhweyitha). Amatye amaninzi arekhoda icala lemagnethi yendawo njengoko eyakheka, kanye njengomculo weerekhodi zeeteyiphu. Ngokomzekelo, iikristale ezincinci zemagnetite yamaminerali eziveliswa zezinye iibhaktheriya ngokwenene zihambelana iinaliti zekhampasi ezincinci kwaye zibambeke kwintlenga njengoko ilitye liqina. Le "fossil" umazibuthe ingasetyenziselwa ukulandelela apho i-axis yojikelezo ihambe khona xa kuthelekiswa noqweqwe loMhlaba.
"Khawufane ucinge ujonge eMhlabeni ukusuka kwindawo," kuchaza umbhali ofundayo uJoe Kirschwenk weTokyo Institute of Technology, apho i-ELSI isekelwe khona. "Inyani yepolar drift ijongeka ngathi uMhlaba ujonge kwicala elinye, xa eyona nto yenzekayo liqokobhe lamatye langaphandle lomhlaba (ingubo eqinileyo kunye noqweqwe) elijikeleza kumbindi wangaphandle wolwelo." I-polar drift yokwenyani yenzekile, kodwa Iingcali ze-Geologists ziyaqhubeka zixoxa ukuba ngaba ukujikeleza okukhulu kwengubo yoMhlaba kunye ne-crust kwenzeka kwixesha elidlulileyo.
Ndiyathemba ukuba ngolu lwazi unokufunda ngakumbi malunga nokuba uMhlaba unokuvula i-axis yawo.