Isikhathi somlando womhlaba silinganiswa ngesilinganiso esikhethekile se-geochronological, esiqukethe izinkathi zokuma komhlaba kanye nezigidi zeminyaka. Zonke izinkomba ezisetafuleni zinobandlululo oluningi futhi zamukelwa ngokujwayelekile emphakathini wezesayensi ezingeni lomhlaba jikelele. Ngokuvamile, ubudala beplanethi yethu buhlehlela emuva eminyakeni engaba yizigidi eziyizinkulungwane ezingu-4,5-4,6. Amaminerali namadwala wokuthandana okunjalo awatholakali kwi-lithosphere, kepha iminyaka yoMhlaba yanqunywa ukwakheka kokuqala okutholakala ohlelweni lwelanga. Lezi yizinto eziqukethe i-aluminium ne-calcium etholakala e-Allende, i-meteorite endala kunazo zonke etholakala emhlabeni wethu.
Ithebula le-geochronological lamukelwa ngekhulu lokugcina. Kusivumela ukuthi sifunde umlando woMhlaba, kepha imininingwane etholakele isivumela ukuthi senze ukucabanga nokwenza okujwayelekile. Itafula luhlobo lokuhleleka kwemvelo komlando weplanethi.
Izimiso zokwakhiwa kwetafula le-geochronological
Izigaba zesikhathi esikhulu setafula Lomhlaba yilezi:
- u-eon;
- inkathi;
- isikhathi;
- inkathi;
- konyaka.
Umlando woMhlaba ugcwele imicimbi eyahlukahlukene. Isikhathi sokuphila kweplanethi sihlukaniswe ngezikhathi ezifana nePhanerozoic ne-Precambrian, lapho kuvela khona amadwala, bese kuzalwa izidalwa ezincane, kwakhiwa i-hydrosphere nomongo weplanethi. Ama-Supercontinents (Vaalbara, Colombia, Rodinia, Mirovia, Pannotia) avele kaningi futhi ahlukana. Ngaphezu kwalokho, kwakhiwa umkhathi, izintaba, amazwekazi, kwavela izinto eziphilayo ezahlukahlukene zafa. Isikhathi sezinhlekelele nokuqhekeka kweplanethi kwenzeka.
Ngokususelwa etafuleni le-geochronological, izilwane zokuqala ezinamaseli amaningi emhlabeni zavela eminyakeni eyizigidi ezingama-635 edlule, ama-dinosaurs - izigidi ezingama-252, nezilwane zesimanje - iminyaka eyizigidi ezingama-56. Ngokuqondene nabantu, izinkawu ezinkulu zokuqala zavela eminyakeni eyizigidi ezingama-33.9 edlule, nabantu banamuhla - eminyakeni eyizigidi ezingama-2,58 edlule. Kungenxa yokubukeka komuntu lapho kuqala khona isikhathi se-anthropogenic noma se-Quaternary, esiqhubeka kuze kube namuhla.
Siphila ngasiphi isikhathi manje
Uma sibonisa isimo sesimanje somhlaba ngokombono wetafula le-geochronological, manje-ke siyaphila:
- I-Phanerozoic eon;
- esikhathini seCenozoic;
- esikhathini anthropogenic;
- ngenkathi ye-Anthropocene.
Okwamanje, abantu bangezinye zezinto ezibalulekile esimisweni semvelo seplanethi yethu. Inhlalakahle yoMhlaba incike kithi. Ukuwohloka kwemvelo kanye nazo zonke izinhlobo zezinhlekelele kungaholela ekufeni hhayi kwabo bonke abantu, kepha nakwezinye izinto eziphilayo ze "planet blue".
