Calymmian
| Calymmian | |
|---|---|
Period | |
| Stratigraphic unit | System |
| Time span formality | Formal |
| Lower boundary definition | Defined chronometrically |
| Lower GSSA ratified | 1991[1] |
| Upper boundary definition | Defined chronometrically |
| Upper GSSA ratified | 1991[1] |
The Calymmian Period (from
Mya to 1400 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically
.
The period is characterised by expansion of existing
.The supercontinent Columbia started to break during the Calymmian some 1500 Mya.
See also
- Boring Billion – Earth history, 1.8 to 0.8 billion years ago
- Jotnian – Oldest known sediments in the Baltic area that have not been subject to metamorphism
References
- "Calymmian 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. .
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