Eoarchean

In the geologic record the Eoarchean erathem /ˌiːoʊ.ɑrˈkiːən/ (also spelled Eoarchaean) and the Eoarchean era in the geologic timescale correspond to one another in the dual system of classification of rock strata laid down beginning 4,000 to 3,600 million years ago. The approximate abiotic origins of life (abiogenesis) have been dated to a time window from 3,900 to 3,500 million years ago when atmospheric pressure values ranged from ca. 100 bar to ca. 10 bar