Revision History

A study published in Science in April 2026 presents evidence that the Colorado River, which disappeared from the geological record for roughly 5 million years, spent that time pooling into a massive lake in the Bidahochi basin of northern Arizona before spilling over to carve the Grand Canyon. The findings, based on detrital zircon geochronology and fossil analysis, revive a long-debated lake spillover hypothesis — though prominent geologists dispute whether the lake was large enough to trigger such an event.