Traditional history, beginning around 3000 bce, depends on dateable written records. The expanded scope of big history (13.8 byr) requires new understandings of time. Following the work of J. T. Fraser, I explore the underlying temporalities of big history. To Fraser’s atemporality and eotemporality, which govern the history of galaxy, star, and planet formation, I add petrotemporaliity which governs three processes—in the freezing of time in mineralized fossils, the chronological structuring of geohistory from stratified rock, and the slow unwinding of time through the decay of radioactive isotopes—and genotemporality which bypasses the vagaries of species transition and extinction, utilizing instead the incorporation of viral dna within the human genome and its continuity of umwelt to construct a big history of life that connects the earliest life forms with humans. I conclude that the possibility of constructing a big history depends on these underlying temporalities.