Stenian
Updated: Wikipedia source
The Stenian Period ( STEE-nee-ən, from Ancient Greek: στενός, romanized: stenós, meaning "narrow") is the final geologic period in the Mesoproterozoic Era and lasted from 1200 Mya to 1000 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically due to the scarcity of Precambrian fossils and lack of reliable zonation. It is preceded by the Ectasian Period and followed by the Neoproterozoic era and the Tonian period. The supercontinent Rodinia finished assembly during the Stenian, having started during the Ectasian. It would last into the Tonian period before breaking up in the Cryogenian. Rodinia was surrounded by the Mirovian ocean during this time. This closed many seas that formed from the breakup of Columbia.