archeano Base of Archean Precambrian Supereon a2.2 Archaean Eoarchean Era Archaikum Archaikum Arcaico Arcaico Base of Proterozoic 太古宙 Paleoproterozoic Era Siderian Period Archean Eon Neoarchean Era Arkæisk Archean Archean Archejus Archaik Archaïcum Proterozoic Eon older bound -4000 Ma прхай Arhaikum Hadean Eon archaikum Mesoarchean Era Geologic Time Scale (2018) younger bound -2500 Ma Paleoarchean Era archaikum, prahory Archéen arkeikum 始生代 Arkeikum Arkeikum arhaik