Major gap in Earth's rock record likely due to tectonics—not glaciers

The Great Unconformity is a major gap in Earth's geologic record. The missing layer between Precambrian and Cambrian rocks represents a gap of around a billion years of history. Among much debate surrounding the cause of the gap, a new study, published in the Proceedings of the National Academy of Sciences, indicates that the timing of the erosion leading to the Great Unconformity aligns with the assembly of the Columbia supercontinent, and that glaciation only contributed minimally.