Evilutionist wrote:Aineo wrote:Theories do abound concerning Pangea don't they? I have seen renderings with a solid mass of land and renderings that show portions of Pangea seperated by small creating more than one land mass.
The sites you linked to are meant to give the general populace an idea of what Pangea looked like and I think you should be careful about saying 'theories abound' about Pangea. Actually, there really is only one theory about Pangea and several hypotheses about its exact makeup. To the best of my knowledge there is no debate in the geological community about the fact that Pangea existed although there are slight deviations regarding its position at different times during its existence (see for example):
Irving, E (2004) The case for Pangea-B, and the intra-Pangean megashear, in Timescales of the Paleomagnetic Field, AGU Geophysical Monograph Series, v 145, p 13-28.
and
Van der Voo, R. and Torsvik, T.H., 2004, The quality of the European Permo-Triassic poles and its impact on Pangea reconstructions, in Timescales of the Paleomagnetic Field, AGU Geophysical Monograph Series, v 145, p 29-42.
The book is available here:
https://www.agu.org/cgi-bin/agubookstor ... EGM1454106
Here is an excerpt from the abstract of Irving's article:
In the mid-1950s it was discovered that paleopoles determined from rocks of Late Carboniferous through Triassic age from Europe and North America came into agreement after closure of the North Atlantic. By contrast, Australian paleopoles from rocks of the same geological systems, although they are brought closer when reassembled into the traditional Pangea configuration (Pangea A), still differed by 15/-20/. This anomaly has now been found throughout Gondwana and it is referred to, therefore, as the Intra-Pangea paleomagnetic (IPP) anomaly. It may have both general and subordinate local causes. Its general characteristics can be explained by placing Gondwana 3-4000 km further east and north with respect to Laurasia, without ocean between them. This is Pangea B. Between the Early and Late Triassic epochs Pangea B was transformed into Pangea A by dextral shear (Trans-Pangea megashear) following the line of the mid-Carboniferous Appalachian-Variscan orogenic belt. This caused rapid opening and extension westward of the NeoTethys Ocean. At first the megashear was thought to be mainly Triassic. Recent interpretations recognize ~3000 km of intra-Permian motion with lesser motion (~500 km) in the Triassic. The precise timing of the magashear is still uncertain.
Over the past three decades difficulties have been raised. The IPP anomaly has been explained by assuming that the geomagnetic field in the Late Carboniferous through Triassic had large, long-term, zonal octupole components, or by invoking reconstruction, inclination or dating errors, or errors in isolating original magnetizations. It is on grounds such as these, that critics have said that Pangea B is “implausible”, that it is “unlikely that Pangea B ever existed”, or that they do not favor “considering Pangea B -- seriously”. Paleomagnetic evidence for megashear has been described as “virtually absent”.
In the past several years, observations, especially from the western Mediterranean region, have removed these difficulties as currently stated. This is not to say that future difficulties will not be raised, but on the basis of present evidence, the ideas of Pangea B and the trans-Pangean megashear survive and are germane to discussions of end-Paleozoic geology.
This abstract illustrates the nature of the debate quite well, but you'll see it's not about IF Pangea existed. What's even more interesting is that Pangea is only the
most recent supercontinent. Geologists have now recognized at least 2 others preceding Pangea (and perhaps more). These are Rodinia that existed from ~1300 Myr to 750 Myr, "Columbia" or "Nuna" that existed around 1900 Myr and also Pannotia that existed fleetingly at the Precambrian-Cambrian boundary. Here are some images of each. They all broke up for the same reason, the buildup of heat beneath the continent. The continents act as a lid on the mantle and cause it to break apart (See Gurnis, 1988 reference below).
RODINIA (see also www.scotese.com)
PANNOTIA
see also:
Powell, C. McA. And Pisarevsky, S., 2002. Late Neoproterozoic assembly of East Gondwana, Geology, 30, 3-6.
COLUMBIA or NUNA
see:
Rogers, J.J.W. and Santosh, M., 2002. Configuration of Columbia, a Mesoproterozoic supercontinent, Gondwana Res., 5, 5-22.
Here is a cartoon image of how heat builds up under a supercontinental lid and also one of supercontinental breakup
BREAKUP
See: http://www.rci.rutgers.edu/~schlisch/vaex03.gif
Lid Photo
SUPERCONTINENTAL LID
See: http://gondwanaresearch.com/downwell2.jpg
Ref: See also:
Gurnis, M. 1988. Large-scale mantle convection and the aggregation and dispersal of supercontinents, Nature, 332, 695-699.
-E