Ancient Mega-Cliff May Reveal Grand Canyon’s Pre-Canyon History

Scientists have identified a colossal cliff system that formed when the supercontinent Rodinia broke apart. This mega-cliff, now lost, would have exposed the core of the Grand Canyon nearly a billion years before the Colorado River began carving the canyon we see today. The discovery offers a plausible explanation for the long‑missing geological record in North America, suggesting that significant portions of the continent’s history were eroded or otherwise removed by this ancient landscape. The finding underscores how tectonic events can shape and obscure the geological record over deep time.