Dhau 150 xyoo dhau los, cov hlau nplaum North Ncej tau yooj yim taug kev 685 mais hla qaum teb Canada Tab sis tam sim no nws tau sib tw 25 mais ib xyoos mus rau sab qaum teb hnub poob. Qhov no tuaj yeem yog lub cim qhia tias peb tab tom yuav ntsib qee yam uas tib neeg tsis tau pom dua ua ntej: qhov sib nqus polar flip.
Thaum twg yog tus ncej kawg ntxeev ntawm lub ntiaj teb?
Magnetic Pole Reversals
Lub sij hawm ncua sij hawm ntawm kev thim rov qab tau hloov pauv dav, tab sis nruab nrab kwv yees li 300,000 xyoo, nrog qhov kawg tshwm sim kwv yees 780,000 xyoo dhau los.
Txoj kev thim rov qab yog dab tsi?
Los ntawm magnetic reversal, los yog 'flip', peb txhais tau tias tus txheej txheem uas tus ncej qaum teb hloov mus rau sab qab teb thiab tus ncej qab teb dhau los ua tus ncej qaum teb.
Puas yog sab qaum teb thiab sab qab teb hloov?
Cov kws tshawb fawb tau paub ntev tias lub ntiaj teb lub tshav pob hlau nplaum hloov pauv, nrog rau sab qaum teb thiab sab qab teb hloov chaw. Qhov kawg paub rov qab - uas yog ib ntus thiab technically hu ua "Laschamps excursion" - tshwm sim 41,000–42,000 xyoo dhau los.
Ntev npaum li cas tus ncej thim rov qab?
Kev kwv yees feem ntau rau lub sijhawm hloov pauv hloov pauv yog nruab nrab ntawm 1, 000 thiab 10, 000 xyoo, tab sis qee qhov kev kwv yees sai li tib neeg lub neej. Cov kev tshawb fawb ntawm 16.7 lab-xyoo lava ntws ntawm Steens Roob, Oregon, qhia tias lub ntiaj teb cov hlau nplaum muaj peev xwm hloov tau ntawm tus nqi txog li 6 degrees ib hnub twg.
