Motherboard reports:

Scientists can reconstruct incredible details about bygone eras in Earth’s history using fossils, rocks, and other clues preserved in its crust. But sometimes, the absence of geological records is just as telling as their presence.

The Great Unconformity, a missing chunk of time that appears in rocks across the world, is the ultimate example of this phenomenon. This giant lapse in Earth’s memory exceeds one billion years in some places, resulting in 550 million-year-old rocks sitting atop ancient layers that date back 1.7 billion years, with no trace of the many lost epochs in between.

For over a century, scientists have debated the cause of this immense geological blackout, which erased a huge chunk of the Neoproterozoic era. Two main explanations have emerged, which are not mutually exclusive: One suggests that tectonic activity associated with the assembly and breakup of the supercontinent Rodinia created the Unconformity, while another points to erosion from widespread glaciation during our planet’s “Snowball Earth” phase some 700 million years ago.

Now, a team led by Kalin McDannell, a postdoctoral researcher in earth sciences at Dartmouth College, has presented new evidence that glaciers were the main force that carved out this mysterious gap in time. [Continue reading…]