Complex sentence: The name of the geologic period refers to the very cold global climate of the Cryogenian: characteristic glacial deposits indicate that Earth suffered the most severe ice ages in its history during this period (Sturtian and Marinoan).
Split into simpler sentences: The name of the geologic period refers to the very cold global climate of the Cryogenian. Characteristic glacial deposits indicate that Earth suffered the most severe ice ages in its history during this period (Sturtian and Marinoan).