View source for Earth:Calymmian

{{short description|First period of the Mesoproterozoic Era}}
{{Infobox geologic timespan
| name                         = Calymmian
| color                        = Calymmian
| top_bar                      = all time
| time_start                   = 1600
| time_end                     = 1400
| image_map                    = 1590 Ma.png
| caption_map                  = Paleoglobe of the Earth at the start of the Calymmian, c. 1590 Ma
| image_outcrop                =
| caption_outcrop              =
| image_art                    =
| caption_art                  =
<!--Chronology-->  
| timeline                     = Calymmian
<!--Etymology-->
| name_formality               = Formal
| name_accept_date             =
| alternate_spellings          =
| synonym1                     =
| synonym1_coined              =
| synonym2                     =
| synonym2_coined              =
| synonym3                     =
| synonym3_coined              =
| nicknames                    =
| former_names                 =
| proposed_names               =
<!--Usage Information--> 
| celestial_body               = earth
| usage                        = Global ([[Organization:International Commission on Stratigraphy|ICS]])
| timescales_used              = ICS Time Scale
<!--Definition-->
| chrono_unit                  = Period
| strat_unit                   = System
| proposed_by                  =
| timespan_formality           = Formal
| lower_boundary_def           = Defined chronometrically
| lower_gssa_accept_date       = 1991<ref name=Plumb1991>{{cite journal |last=Plumb |first=K. A. |date=June 1, 1991 |title=New Precambrian time scale |journal=Episodes |doi=10.18814/epiiugs/1991/v14i2/005 |volume=14 |issue=2 |pages=139–140|doi-access=free }}</ref>
| upper_boundary_def           = Defined chronometrically
| upper_gssa_accept_date       = 1991<ref name=Plumb1991/>
<!--Atmospheric and Climatic Data-->
| o2                           =
| co2                          =
| temp                         =
| sea_level                    =
}}
The '''Calymmian Period''' (from {{lang-grc|κάλυμμα|kálymma}}, meaning "cover") is the first geologic period in the [[Earth:Mesoproterozoic|Mesoproterozoic]] [[Earth:Era (geology)|Era]] and lasted from {{Period start|Calymmian}} Mya to {{Period start|Ectasian}} Mya (million years ago). Instead of being based on [[Earth:Stratigraphy|stratigraphy]], these dates are defined [[Physics:Absolute dating|chronometrically]].

The period is characterised by expansion of existing platform covers, or by new [[Earth:Continental shelf|platform]]s on recently [[Earth:Craton|craton]]ized [[Earth:Basement (geology)|basement]]s.

The [[Earth:Supercontinent|supercontinent]] [[Earth:Columbia (supercontinent)|Columbia]] started to break up during the Calymmian some 1500 Mya.

The [[Biology:Volyn biota|Volyn biota]] have been dated to 1500 Mya.

==See also==
*{{annotated link|Earth:Boring Billion}}
*{{annotated link|Earth:Jotnian}}

==References==
*{{cite web|title=Calymmian Period |work=GeoWhen Database |url=http://www.stratigraphy.org/geowhen/stages/Calymmian.html |access-date=January 5, 2006 |archive-url=https://web.archive.org/web/20060512210318/http://www.stratigraphy.org/geowhen/stages/Calymmian.html |archive-date=May 12, 2006 |url-status=dead }}
*{{cite journal | author=James G. Ogg | title=Status on Divisions of the International Geologic Time Scale | journal=Lethaia | year=2004 | volume=37 | issue= 2| pages=183–199 | doi=10.1080/00241160410006492 }}

{{reflist}}


[[Category:Mesoproterozoic]]
[[Category:Geological periods]]



{{Sourceattribution|Calymmian}}