Rodinia: Perbedaan revisi

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Other cratons such as the Kalahari (southern Africa), the Congo (west-central Africa), and the San Francisco (southeastern South America), appear to have been separate from the rest of Rodinia.
Rodinia's landmass was probably centered south of the [[ekuator]].<ref>{{cite web | url = | title = Rodinia | publisher = Palaeos | accessdate = 2006-03-10}}</ref> Because Earth was at that time experiencing the [[Cryogenian]] period of [[glaciation]], and temperatures were at least as cool as today, substantial areas of Rodinia may have been covered by [[glacier]]s or the southern [[polar ice cap]]. The interior of the continent, being so distant from the temperature-moderating effects of the ocean, was probably seasonally extremely cold (see [[continental climate]]). It was surrounded by the [[superocean]] geologists are calling [[Mirovia]] (from ''mir'', the Russian word for "globe").
Cold temperatures may have been exaggerated during the early stages of continental rifting. [[Geothermal heating]] peaks in crust about to be rifted; and since warmer rocks are less [[Density|dense]], the crustal rocks rise up relative to their surroundings. This rising creates areas of higher altitude, where the air is cooler and ice is less likely to melt with changes in season, and it may explain the evidence of abundant glaciation in the [[Ediacaran]] period.<ref name="mcmenamin">{{cite book | last = McMenamin | first = Mark A. | coauthors = Dianna L. McMenamin | title = The Emergence of Animals | origdate = 1990-01-15 | id = ISBN 0-231-06647-3 | chapter = The Rifting of Rodina}}</ref>
The eventual rifting of the continents created new oceans, and [[seafloor spreading]], which produces warmer less-dense rock, probably increased sea level by displacing ocean water. The result was a greater number of shallower oceans.
The [[evaporation]] from these oceans may have increased rainfall, which, in turn, increased the weathering of exposed rock. By inputting data on [[Δ18O|the ratio of stable isotopes <sup>18</sup>O:<sup>16</sup>O]] into computer models, it has been shown that in conjunction with quick-weathering of [[volcanic rock]], this increased rainfall may have reduced [[greenhouse gas]] levels to below the threshold required to trigger the period of extreme glaciation known as [[Snowball Earth]].<ref>{{cite journal | last = Donnadieu | first = Yannick | coauthors = Yves Goddéris, Gilles Ramstein, Anne Nédélec, Joseph Meert | year = 2004 | month = March | title = A 'snowball Earth' climate triggered by continental break-up through changes in runoff | journal = Nature | volume = 428 | pages = 303–306 | doi = 10.1038/nature02408}}</ref>
All of this [[Plate tectonics|tectonic]] activity also introduced into the marine environment biologically important nutrients, which may have played an important role in the development of the earliest animals.
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