evidence: The research presents the latest findings in a debate over what caused the Earth's "Great Unconformity" -- a time gap in the geological record associated with the erosion of rock up to 3 miles thick in areas across the globe. [...] Research led by Keller in 2019 first proposed that widespread erosion by continental ice sheets during the Cryogenian glacial interval caused the loss of rock. This was based on geochemical proxies that suggested that large amounts of mass erosion matched with the Snowball Earth period. [...] "The underlying concept is pretty simple: Something removed a whole lot of rock, resulting in a whole lot of missing time," said Keller. "Our research demonstrates that only glacial erosion could be responsible at this scale."