evidence: - Inspired during field work in South Australia's Flinders Ranges, geoscientists have proposed that all-time low volcanic carbon dioxide emissions triggered a 57-million-year-long global 'Sturtian' ice age. [...] "We now think we have cracked the mystery: historically low volcanic carbon dioxide emissions, aided by weathering of a large pile of volcanic rocks in what is now Canada; a process that absorbs atmospheric carbon dioxide." [...] They soon realised that the start of the Sturtian ice age precisely correlates with an all-time low in volcanic CO2 emissions. In addition, the CO2 outflux remained relatively low for the entire duration of the ice age.