The Stenian Period (/ˈstiːni.ən/ 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. The name derives from narrow polymetamorphic belts formed over this period. It is preceded by the Ectasian Period and followed by the Neoproterozoic era and the Tonian period.
| Stenian | ||
|---|---|---|
 Paleoglobe of Earth during the late Stenian, c. 1040 Ma[citation needed] | ||
| Chronology | ||
Events of the Stenian Period. Axis scale: millions of years ago. | ||
The supercontinent Rodinia assembled during the Stenian. It would last into the Tonian period before breaking up in the Cryogenian.
This period includes the formation of the Keweenawan Rift at about 1100 Mya.[5]
Fossils of the oldest known sexually reproducing organism, Bangiomorpha pubescens, first appeared in the Stenian.[1]
See also
- Boring Billion – Earth history, 1.8 to 0.8 billion years ago
- Riphean (stage) – stage in the geological timescale named after the Urals
Notes
References
- "Stenian Period". GeoWhen Database. Archived from the original on May 12, 2006. Retrieved January 5, 2006.
- James G. Ogg (2004). "Status on Divisions of the International Geologic Time Scale". Lethaia. 37 (2): 183–199. doi:10.1080/00241160410006492.