Isikhathi se-Quaternary

Kokuthunyelwe kwangaphambilini sihlaziye ukuthi kusebenza kanjani isikhathi sokuma komhlaba futhi ibuyekeze izehlakalo ezibaluleke kakhulu ezenzeka ku- Isikhathi seMesozoic futhi ku I-Precambrian Aeon. Namuhla sibuyela ku i-Cenozoic Era lapho sizohlaziya khona ukuthi kwenzekani ku isikhathi se-Quaternary. Lesi yisikhathi sokugcina se-Cenozoic Era futhi sihlanganisa izinkathi ezimbili "zesimanje" kakhulu, iPleistocene neHolocene.

Ngabe uyafuna ukwazi izehlakalo ezibaluleke kakhulu ezenzeke kulesi sikhathi? Qhubeka ufunde ngoba sikutshela konke.

Ukufika kweqhwa nendoda

Ngemuva kokudlula kwezigidi zeminyaka, sisondela kulokho obekuyikho "namuhla". KuQuaternary, okuyi yaqala eminyakeni eyizigidi ezingama-2,59 edlule, yisikhathi esiphila kuso namuhla. IQuaternary ayibandakanyi iPleistocene neHolocene kuphela, kepha nokuvumelana lapho kwenziwa okutholakele mayelana nezinguquko ezenzeka emhlabeni, kungafakwa inkathi yeGelasian. Ngalesi sikhathi kube nezinguquko ezibaluleke kakhulu empilweni emhlabeni, isimo sezulu nolwandle ngenxa yeziqephu zeminyaka yeqhwa.

Izikhathi ezimbili zeQuaternary yiPleistocene neHolocene. IPleistocene yinde kakhulu futhi ihlanganisa izinguzunga zeqhwa ezingamakhulu namakhulu eminyaka. Kuyaziwa njenge Isikhathi seqhwa. Ukuya esikhathini sakamuva kakhulu sineHolocene, ebhekwa njengengxenye yangemva kweqhwa futhi yilokho esinakho namuhla.

Lapho kukhulunywa ngePleistocene, abantu abaningi bakhuluma ngayo "Iminyaka yomuntu" selokhu uhlobo loHomo lwaqala ukuvela ngalesi sikhathi. Sekuvele lapho eHolocene, umuntu angathuthukisa impilo ehlelwe ngamaqembu ezenhlalo futhi ebizwa ngempucuko.

Izici ze-Pleistocene

Siqala ngokuchaza iQuaternary ngenkathi yayo yokuqala. Iminyaka eyizigidi ezingama-2,59 edlule inika indlela ukuqala kwePleistocene ephela eminyakeni eyi-12.000 eyedlule. Ngalesi sikhathi iqhwa lasakazeka ngesimo seqhwa kuze kube zithatha ngaphezu kwengxenye yesine yomhlaba. Iqhwa lafinyelela ezindaweni ezingakaze zifinyelelwe ngaphambili. Futhi ngukuthi uma sikhuluma nge-glaciation noma i-ice age, okucatshangwa ukuthi umhlaba wonke umbozwe yiqhwa, kubandakanya nezilwandle. Lokhu akufani nalokhu. Cishe ama-25% womhlaba wonke ovalwe yiqhwa akujwayelekile ngendlela emangalisayo.

Ngenxa yenani elikhulu leqhwa emhlabeni, izinga lolwandle lehle lafika kumamitha ayi-100 futhi impilo emhlabeni kwakufanele ivumelane nezimo ezintsha zemvelo noma inyamalale. Ezindaweni lapho kwakungekho khona iqhwa, cishe zonke izitshalo nezilwane ezazifana ngesikhathi esifanayo (Pliocene).

Kwakukhona ezinkulu izinhlelo zeqhwa zisakazeke ezindaweni ezinamakhaza nezinamaqhwa. Owokuqala kwakuyiqhwa leqhwa eScandinavia elalinweba eningizimu nasempumalanga kuyo yonke inyakatho yeJalimane nasentshonalanga yeRussia. Ifike eBritish Isles, ngakho-ke ungacabanga ubukhulu balelo qhwa.

Ngakolunye uhlangothi, sithola nolunye uhlelo olukhulu lweqhwa olusendaweni yonke yeSiberia. Olunye uhlelo lweqhwa lwasakazeka ukusuka eCanada kuya e-United States. Zonke lezi zakhiwo zeqhwa, ngemuva kokuguquguquka kwazo nokwakheka kwazo, kwaveza ukwakheka kweqhwa esingakubona namhlanje kuzo zonke lezi zindawo.

Ama-glaciations, izimbali nezilwane

Njengoba kungaqagelwa, izifunda ze-Arctic ne-Antarctic nazo zazimbozwe yiqhwa, njengezintaba eziningi emhlabeni wonke. Izinga leqhwa lehlele emazingeni angakaze abonwe namuhla. Njengoba ngishilo ngaphambili, zonke izenzo zezinguzunga zeqhwa nokuncibilika kwazo okulandelayo kungabonakala nanamuhla ezingxenyeni eziningi zomhlaba.

Kwakungekhona kuphela ukuthi kwakukhona i-glaciation eyodwa ngesikhathi sePleistocene, kepha kwakukhona abayisithupha. Phakathi kwazo ngakunye kwakukhona izikhathi lapho isimo sezulu sasifudumele ngandlela thile futhi neqhwa lehla futhi. Okwamanje, sithathwa njengenye yalezo zikhathi "zokuphumula" zeqhwa.

Ngokuqondene nezimbali nezilwane okwakufanele zivumelane nezindawo eziqhwa ngokuphelele, sathola ama-mammoths, ama-reindeer, izinyamazane ezinkulu namabhere asezindaweni eziphakeme. Izimila ezikule ndawo zazakhiwe ngokuphelele ngobulembu nobulembu. Kwakufana ngokuphelele ne-tundra yamanje. Ngezigaba ezahlukahlukene, ezinamazinga okushisa aphakeme nangaphezulu okumbozwe yiqhwa, angaphila amahhashi, izinsikazi ezinamazinyo amakhulu nobhejane.

Ezinye izinhlobo ezimbalwa zezilwane zizivumelanise kahle nezinguquko zezulu ukuze ziphile isikhathi eside. Sikhuluma nge-bison, i-elk, i-fox, ne-wildcat. Ezingxenyeni ezibandayo zaseNyakatho Melika, izinhlobo ezinjenge ikamela, i-yak, i-llama, i-tapir nehhashi. Ngesikhathi i-Pleistocene iphela, izinhlobo ezinkulu zezilwane ezincelisayo ezinjenge-mastodon, ingwe edume ngamazinyo ama-saber, nenyamazane enkulu kwase kuphelile ngayo yonke iplanethi.

Ukuziphendukela kwabantu kanye neHolocene

Manje sikhuluma ngokuvela komuntu lapho sinePaleolithic ePleistocene, lapho i- Homo habilis waqala ukubutha nokuzingela. Kamuva, Homo erectus ekugcineni wenza izikhali eziyinkimbinkimbi futhi wazingela ngamaqembu. I-Homo neanderthalensis kwakuyizinhlobo eziguqulelwe emakhazeni avele eminyakeni engama-230.000 eyedlule.

Siqhubeka nokuchaza inkathi yakamuva kakhulu yeQuaternary: iHolocene. Yilapho sikhona namhlanje. Kwaqala eminyakeni eyi-12.000 eyedlule futhi ukuhamba kwayo kokushintsha kwamazinga okushisa kwaqala isikhathi sokuncibilika emhlabeni wonke. Lokhu kuncibilika kubangele ukukhuphuka kolwandle ngamamitha angamashumi amathathu.  Kuthiwa lesi sikhathi esiphakathi kwezinhlanga ezithile singaphela enkathini entsha yeqhwa.

Kule minyaka eyi-12.000, ukuqothulwa kwezinto kuqhubekile futhi kusheshiswe kakhulu kule minyaka eyi-100 edlule ngokuba khona kwabantu nokuthuthukiswa kobuchwepheshe. Emhlabeni kube nokuqothulwa okungu-5 okukhulu. Ngalesi sizathu, ukubulawa kwabantu abaningi kangaka okubizwa ngakho namuhla kuyabizwa ukuqothulwa kwesithupha.

Impilo yokuzulazula yomuntu iphele ngokwakhiwa kwezolimo nemfuyo. Ukudoba futhi kwakuthanda kakhulu ukuthuthukiswa komuntu. Ekugcineni, iHolocene ivame ukufundwa kuze kusungulwe ukubhala, lapho lokho esikubiza ngokuthi uMlando kuqala ukufundwa.

Ngiyethemba lokhu okuthunyelwe kukwenze wazi kabanzi ngesikhathi sokugcina soMhlaba.