Editing Cryogenian (section)

== Paleogeography ==
{{main|Rodinia#Geodynamics}}
Before the start of the Cryogenian, around 750 Ma, the [[cratons]] that made up the supercontinent [[Rodinia]] started to rift apart. The superocean [[Mirovia]] began to close while the superocean [[Panthalassa]] began to form. The cratons (possibly) later assembled into another supercontinent called [[Pannotia]], in the [[Ediacaran]].<ref>{{Cite journal |last1=Nance |first1=R. Damian |last2=Evans |first2=David A. D. |last3=Murphy |first3=J. Brendan |date=2022-09-01 |title=Pannotia: To be or not to be? |url=https://www.sciencedirect.com/science/article/pii/S0012825222002124 |journal=Earth-Science Reviews |volume=232 |pages=104128 |doi=10.1016/j.earscirev.2022.104128 |bibcode=2022ESRv..23204128N |issn=0012-8252|url-access=subscription }}</ref>

Eyles and Young state, "Most Neoproterozoic glacial deposits accumulated as glacially influenced marine strata along rifted continental margins or interiors."  Worldwide deposition of dolomite might have reduced atmospheric carbon dioxide.  The break up along the margins of [[Laurentia]] at about 750 [[Myr|Ma]] occurs at about the same time as the deposition of the Rapitan Group in North America, contemporaneously with the Sturtian in Australia.  A similar period of rifting at about 650 Ma occurred with the deposition of the Ice Brook Formation in North America, contemporaneously with the Marinoan in Australia.<ref name="Eyles-1994"/> The Sturtian and Marinoan are local divisions within the [[Adelaide Rift Complex]].<ref>{{Cite journal |last1=Haines |first1=Peter W. |last2=Turner |first2=Simon P. |last3=Kelley |first3=Simon P. |last4=Wartho |first4=Jo-Anne |last5=Sherlock |first5=Sarah C. |date=2004-11-15 |title=40Ar–39Ar dating of detrital muscovite in provenance investigations: a case study from the Adelaide Rift Complex, South Australia |url=https://www.sciencedirect.com/science/article/abs/pii/S0012821X04005230 |journal=Earth and Planetary Science Letters |volume=227 |issue=3 |pages=297–311 |doi=10.1016/j.epsl.2004.08.020 |issn=0012-821X|url-access=subscription }}</ref>