🪨 NEW: Layers of rock usually stack in order from oldest to youngest, but on several continents a span of hundreds of millions of years is missing, a gap called the 'Great Unconformity.'
New modeling indicates slow mantle motion lifted three ancient continents, and 'Snowball #Earth' ice sheets then scoured their surfaces bare before the land sank and new sediment was laid down.
#geology #erosion #glaciers #mantle #rocks #grandcanyon #cambrian #fossils #science #planet #history #supercomputers