OP
Senior Member
Joined: May 2010
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The standard model of Pangaea is False?Imagine believing in a model of Earth, with one hemisphere being the continent of Pangaea and the opposite hemisphere being ocean.
Such an arrangement would be completely unbalanced with regards to the supposed spin axis of the time.
This model, that most believe in, is clearly fictional.
The Earth would spin erratically, and violently, until the spin axis lined up with the center of mass of Pangaea, which is somewhere in North-East Africa.
Small problem: There is no evidence that the rotational pole has ever been in North-East Africa.
Large problem: Before the spin axis can change, the mass of the equatorial bulge has to be redistributed to the new equator, i.e., billions of cubic kilometers of mass have to be moved to the new equatorial bulge and away from the old. This is no easy task and is the reason for the predicted violence of the change.
Some scientists have speculated that the stress caused by the spin axis moving toward a new balanced arrangement, caused the breakup of Pangaea.
However, most "scientists" quietly ignore this HUGE problem.
So, is the unbalanced nature of Pangaea really a problem for the model?
After composing the above I hunted for one of the references to scientists saying "that the stress caused by the spin axis moving toward a new balanced arrangement, caused the breakup of Pangaea." I couldn't be bothered typing out the whole section, so I just grabbed sentences here and there. The whole section does not read that well, so the isolated sentences won't either.
Don Anderson in his book "Theory of the Earth." writes;
"Page 70; Polar wander.
Because the Earth is a dynamic body, it is impossible to define a permanent internal reference frame....
The outer layers of the mantle, including the brittle lithosphere, do not fit properly on a reoriented Earth. Membrane stresses generated as plates move around the surface, or as the rotational bulge shifts, may be partly responsible for the breakup and dispersal of Pangea. In this scenario, true polar wandering and continental drift are intimately related. A long period of continental stability allows thermal and geoid anomalies to develop. A shift of the axis of rotation can cause plates to split....
Polar wandering can occur on two distinct time scales. In a slowly evolving mantle the rotation axis continuously adjusts to changes in the moments of inertia. This will continue to be the case as long as the major axis of inertia remains close to the rotation axis. If one of the other axes becomes larger, the rotation vector swings quickly to the new major axis....
The principal moments of inertia shown on a cusp catastrophe diagram. As the moments of inertia vary, due to convective processes in the interior, the pole will slowly wander unless the ratios of the moments x1, and x2, pass through unity, at which point a catastrophe will occur, leading to a rapid change in the rotation axis....
The interchange of moments of inertia, however, occurs more quickly, and a large-scale 90-degree shift can occur on a timescale limited only by the relaxation time of the rotational bulge.....
Thus, expanding the paradigm of continental drift and plate tectonics to include continental insulation and true-polar wandering may explain the paradoxes of synchronous global tectonic and magmatic activity, rapid breakup and dispersal of continents following long periods of continental stability,... (these are problems the average jock never hears about)
Curiously, Earth scientists have been more reluctant to accept the inevitability of true-polar wandering than to accept continental drift, even though the physics of the former is better understood. (the Earth scientists that refuse to accept polar wander know that it inevitably leads to a rejection of the official concept of Pangea)."
Don Anderson is a Professor (Emeritus) of Geophysics at the California Institute of Technology (Caltech).
At some point I will also start up a thread on this at my forum;
http://www.preearth.net/phpBB3/search.php?search_id=newposts
Last edited by preearth; 07/08/10 11:20 AM.
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