Umhlaba uneminyaka emingaki?
Context:Isikali sesikhathi sokuma komhlaba siyindlela yokumelela isikhathi esijulile esisekelwe ezenzakalweni ezenzeka kuwo wonke umlando woMhlaba, isikhathi esiyiminyaka engaba ngu-4.54 ± 0.05 Ga (iminyaka eyizigidi eziyizinkulungwane ezingu-4.54). Lihlela ngokulandelana kwezikhathi izingqimba, futhi kamuva nesikhathi, ngokubheka izinguquko eziyisisekelo ku-stratigraphy ezihambisana nezenzakalo ezinkulu zokwakheka komhlaba noma ze-paleontological. Isibonelo, isenzakalo sokushabalala kweCretaceous<unk>Paleogene, sibonisa umkhawulo ophansi wePaleogene System / Period futhi ngaleyo ndlela umngcele phakathi kweCretaceous nePaleogene Systems / Periods. Ngokuhlukaniswa ngaphambi kwe-Cryogenian, izincazelo zemingcele yezinombolo ezingahleliwe (Global Standard Stratigraphic Ages, GSSAs) zisetshenziselwa ukuhlukanisa isikhathi sokuma komhlaba. Kuye kwenziwa iziphakamiso zokuvumelanisa kangcono lezi zingxenye namarekhodi amatshe.
Umhlaba uneminyaka engaba yizigidi eziyizinkulungwane ezingu-4,54 ubudala.