Calymmian

The Calymmian Period (from Greek κάλυμμα (kálymma), meaning "cover") is the first geologic period in the Mesoproterozoic Era and lasted from 1600 Mya to 1400 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically.

Calymmian Period 1600–1400 million years ago PreꞒ Ꞓ O S D C P T J K Pg N

Paleoglobe of the Earth at the start of Calymmian

Events of the Calymmian -1600 — – -1580 — – -1560 — – -1540 — – -1520 — – -1500 — – -1480 — – -1460 — – -1440 — – -1420 — – -1400 — – P P Z M e s o p r o t e r o z o i c Statherian Calymmian Ectasian     ← Breakup of the supercontinent Columbia Events of the Calymmian Period. Axis scale: millions of years ago.

The period is characterised by expansion of existing platform covers, or by new platforms on recently cratonized basements.

The supercontinent Columbia started to break during the Calymmian some 1500 Mya.

See also

• Boring Billion – Between 1.8 and 0.8 billion years ago
• Jotnian – The 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. doi:10.1080/00241160410006492.