Ubume Bomhlaba
Kwiminyaka engama khulu ezigidi eliqela, uMhlaba waqala ukuphola yaze ne celestial bombardment yehla, mhlawumbi kungenxa yokuba uninzi lwe bolides kwi solar system yayisele iwele phezu kwento okanye zaziphelile. Umphunga, icarbon dioxide kunye nezinye iigesi zaphuma kwiintanda eziqhumayo zomphezulu womhlaba zaze zaqala ukudala umoya (atmosphere). Imvula yaqala ukuna aze namalwandle aqala ukudama kwi crust enamatye yomhlaba. Amanzi phezu komhlaba ayesele ekhona kwiminyaka ezii bhiliyoni ezi 3.9 billion eyadlulayo.Ixesha le Archaean
Oku kukuqala kwexesha Archaean (elithetha kudala-dala ) kwaye yabakhona de yabayiminyaka eziibhiliyoni ezi 2.5 eyadlulayo. Ngelixesha, amabhanti alekeneyo amatye abizwa ngee Granite-Greenstone zadaleka, ziseka umandlalo walo lonke utshintsho lokumila komhlaba olwathi lwalandela. Owona mzekelo we crust yexesha le Archaean esagcinwe ngendlela , nesabonakalayo eMhlabeni ingafumaneka eMpumalanga kwidolophu yase Barbeton.Lendawo kulapho Granite-Greenstone strata zakudala-dala zaphethuka khona zavela ngaphezu komhlaba. Lamatye e ntabamlilo(volcanic) , abizwa nge komatiities, adaleka kwi ancient seabed phakathi kwe 3.6 kunye ne 3.2 billion yeminyaka ubudala. Ukubumbeka kwawo kubonisa ukuba ayedaleke ngethuba apho amaqondo obushushu kwi mantle ayethande ukubaphezulu kunalawo alemihla. Oku ke kubonisa ukuba uMhlaba uye uqhubeka ngokuphola ngokuye kuhamba izigidi zeminyaka.
Njengokuba le crust iya iqina, isilica-rich material (neyayimanzana kunomhlaba onyibilikileyo ngaphantsi komhlaba) yayithanda ukunyukela ngaphezulu ize iqokelelane ngaphezu kwe mantle. Kuba yayi ‘khaphu-khapu’ kune mantle kunye nomandlalo wolwandle. Lamatye azele yi silica ayengekho zange antywile aze ahlala edada ngaphezulu, aze ethubeni aya ebangqindilili ngokwaneleyo ukunyukela ngaphezu kwamanzi njenge ziqithi.
IiCratons
Ekuhambeni kwexesha , iziqithi ezitsha zaqhubeka nokudada phezu kwe tectonic plates, zimana zingqubana kwaye zidibana, de kwabe amaqhekeza omhlaba abe ayadaleka kwiindawo ezahlukeneyo zoMhlaba. Oludibaniselwano lubizwa ngee ‘micro-continents’. Ngaxeshanye, amatye avele phezu komhlaba aqala ukukhukuliseka ngumoya kunye namanzi ahambayo, kwaye amaqhekeza amatye abolileyo alahlelwa ecaleni phakathi komhlaba kunye nolwandle. Lamatye abumba i gravel conglomerates, amatye esanti kunye namatye odaka.Ilizwe kazi laqalisa ukubumbeka. Ukwenza lifutshane ibali elide, lamazwekazi ayendanda asekuqaleni aqhubeka nokukhula. Kuba ke ayengomelelanga ukogqitha umandlalo wolwandle, kwabanzima kakhulu ukuba antywiliseleke. Amanye amaceba alamazwekazi asala endanda kangangeminyaka ezi bhiliyoni ezi 3 ezilandelayo. Asenokuba ahlukana aphinda adibana amatyeli amaninzi, kodwa awazange atshabalale okanye onakale. Namhlanje, siwabiza lamasuntswana azinzileyo e-ancient crust njengee ‘cratons’.
I-Kaapvaal Craton
Enye yeecratons zokuqala ehlabathini yi Kaapvaal Craton, nesahleli kumbindi wMazantsi Afrika. Owona mlinganiselo wale craton awaziwa, kodwa uphando lubonise ukuba icala langase mpuma lo Mzantsi Afrika, elase ntshona eAustralia, India kunye ne Madagascar zonke zazidibene kweli lizwekwazi lakudala-dala. Ngokuhamba kweminyaka, iilayers ezintsha zamatye zakhwela phezu komandlalo we Granite-Greenstone ye craton, kwakunye nesibalo esincomekayo se minerali zaxabiso. I-Kaapvaal Craton nayo yabayi yindawo yexhwayelo ye Yontlitheko lwase VredefortUmandlalo wokuqala wamatye amatsha adaleka kwi Kaapvaal craton ibizwa ngokuba yi Dominion group. Iquka umandlalo oceke-ceke wamatye aludaka agubekayo yaze ngaphezulu kwabakho omnye umandlalo obukuqina wamatye igneous. Amatye aludaka-agubekayo enzeka xa amasuntswana amatye akhukulisekileyo ashiywe kwindawo entsha aze ethubeni ajike abelilitye, ngendlela ebizwa nge lithification. Amatye a-igneous, wona kwelawo icala, enzeka xa kubekho intaba mlilo (volcano) kwi mantle kunye ne crust engaphezulu, nalapho imagma ingena phakathi kweentanda kwi rust de iphole iqine. Ilava ephuphumela phezu komhlaba nayo ingenza amatye e-igneous.
Translated by Zizipho Silwana