Summary in Seconds The Great Unconformity is one of geology’s most intriguing mysteries: enormous spans of geological time are missing because vast quantities of rock were eroded away or never deposited. While scientists have often linked this erosion to the Snowball Earth glaciations of roughly 700 million years ago, new research from the North China Craton suggests that much of the story may be far older. By analyzing minerals that preserve clues about the temperature and depth history of ancient rocks, researchers found evidence that substantial uplift and erosion occurred between about 2.1 and 1.6 billion years ago, with much