Ubuso beplanethi yethu abuyona i-monolithic; inamabhulokhi aqinile abizwa ngokuthi ama-slabs. Zonke izinguquko ezingapheli - ukuzamazama komhlaba, ukuqhuma kwentaba-mlilo, ukwehla nokwenyuka kwezindawo zomhlaba ngamunye - kwenzeka ngenxa yama-tectonics - ukuhamba kwamapuleti e-lithospheric.
U-Alfred Wegener wayengowokuqala ukubeka phambili umbono wokukhukhuleka kwezindawo zomhlaba ezihlukile ezihlobene komunye nomunye ngonyaka we-1930 wekhulu elidlule. Uveze ukuthi ngenxa yokuhlangana okungaguquguquki kwezingcezu eziminyene ze-lithosphere, amazwekazi akhiwa eMhlabeni. Isayensi yathola isiqinisekiso samazwi akhe kuphela ngo-1960, ngemuva kocwaningo lwaphansi lolwandle, lapho izinguquko ezinjalo ebusweni beplanethi zalotshwa ngososayensi bezilwandle nezazi zokwakheka komhlaba.
Ama-tectonics anamuhla
Ngalesi sikhathi ngokuhamba kwesikhathi, ubuso beplanethi buhlukaniswe baba amapuleti amakhulu ayi-8 we-lithospheric namabhulokhi ayishumi nambili. Lapho izindawo ezinkulu ze-lithosphere zihlukana ngezindlela ezahlukahlukene, okuqukethwe kwengubo yeplanethi kuqhuma kuqhume, kuphole, kwakheke phansi koLwandle Lomhlaba, bese kuqhubeka nokusunduza amabhlogo ezwekazi ahlukane.
Uma amapuleti edudulana, kwenzeka izinhlekelele zomhlaba, ezihambisana nokucwiliswa kwengxenye yebhulokhi engezansi engubeni. Ngokuvamile, ngezansi ipuleti lasolwandle, okuqukethwe kwalo okulungiswa ngaphansi kwethonya lamazinga okushisa aphakeme, abe yingxenye yengubo. Kulokhu, izinhlayiya ezilula zodaba zithunyelwa emiphethweni yezintaba-mlilo, ezisindayo zihlala, zicwila ezansi kwengubo evuthayo yeplanethi, zikhangwa umongo wayo.
Lapho kushayisana amapuleti ezwekazi, kwakhiwa izakhiwo zezintaba. Umuntu angabona into efanayo ne-ice drift, lapho iziqeshana ezinkulu zamanzi afriziwe zihamba phezu komunye nomunye, zidilika futhi zephuka. Yile ndlela cishe ezakhiwe ngayo zonke izintaba emhlabeni, ngokwesibonelo, iHimalaya kanye ne-Alps, iPamir kanye ne-Andes.
Isayensi yanamuhla ibalwe ijubane elilinganisiwe lokuhamba kwamazwekazi ngokuhlobene:
- IYurophu ihlehla eNyakatho Melika ngesilinganiso samasentimitha ama-5 ngonyaka;
- I-Australia “ibalekela” iSouth Pole ngamasentimitha ayi-15 njalo ezinyangeni eziyi-12.
Amapuleti asolwandle ashukumisayo ashesha kakhulu, angaphambi kwamazwekazi ngezikhathi eziyi-7.
Ngenxa yocwaningo olwenziwe ososayensi, kwavela isibikezelo sokuhamba kwesikhathi esizayo kwamapuleti e-lithospheric, lapho kuzonyamalala khona uLwandle iMedithera, iBay of Biscay izovalwa, kanti i-Australia izoba yingxenye yezwekazi lase-Eurasia.
