Cryogenian
Geologic period
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The Cryogenian is a geologic period that lasted from 720 to 635 million years ago. It forms the second geologic period of the Neoproterozoic Era, preceded by the Tonian Period and followed by the Ediacaran.
The Cryogenian was a time of drastic... Wikipedia
Occurred: 720 million years ago - 635 million years ago
Era: Neoproterozoic
Lower boundary definition: Defined chronometrically with an interim calibrated age of c. 720 Ma. GSSP is in progress
Lower boundary GSSP candidate section(s): To be determined
Stratigraphic unit: System
Upper boundary definition: Worldwide distinct cap carbonates. Beginning of a distinctive pattern of secular changes in carbon isotopes
Upper boundary GSSP: Enorama Creek section, Flinders Ranges, South Australia; 31°19′53″S 138°38′00″E / 31.3314°S 138.6334°E