Future Continental drift, OERDIN!!!

[Odin]

The Yellowstone tread gave me the Idea for this thread, how will the continents move in the future. I have heard many conlflicting ideas. here is my ideas:

North America: rotates clockwise, California moves up the coast, continent starts to move generally SW, Greenland rotates counter-clockwise and moves NW.

South America: moves NW, continues to subduct Nazca plate, crashes into S. Mexico forming mountains.

Eurasia: rotates counter-clockwise, moves SE, collides with N. America and forms mountains

[Nubclear]

Originally posted by Odin
Eurasia: rotates counter-clockwise, moves SE, collides with N. America and forms mountains

I dread to think what will happen....

[mrmitchell]

Question: Would an endless rain of nuclear holocaust seriously effect any of the geologic factors that shape the world?

[Odin]

OOPS, DP, Ming, erase this thread, go the the other copy guys.

[Oerdin]

The Yellowstone tread gave me the Idea for this thread, how will the continents move in the future. I have heard many conlflicting ideas. here is my ideas:

North America: rotates clockwise, California moves up the coast, continent starts to move generally SW, Greenland rotates counter-clockwise and moves NW.

South America: moves NW, continues to subduct Nazca plate, crashes into S. Mexico forming mountains.

Eurasia: rotates counter-clockwise, moves SE, collides with N. America and forms mountains, India finishes penitration of Eurasia.

Africa: Moves N, collides with Eurasia, Mediterrainean Sea closes, Alps grow enourmously, E. Africa rifts from continent and closes the Arabian sea, Red Sea expands to form new ocean basin.

Australia: moves N at fast clip, eventually collides with NW Asia, forming mountains

Antarctica: ???

Have you ever heard of a German mathematician named Euler? He came up with a way to compute "Euler poles" which allow us to figure out how flat objects rotate on the surface of a sphere. Without that we would be hard pressed to computer the exact tectonic movements of the Earth's many plates.

Now, why are contents moving? To understand the why you have to know that the Earth's crust is broken up into Oceanic crust, which is relatively thin and dense (because it is "mafic" i.e. it contains a large proportion of metals especially iron and aluminum), where as the continental crust is relatively thick and low density (that's because it is "felsic" or contains much more silicates (SiO4) and much less metals). Because the contential crust is so much less dense it ends up "floating" upon the Earth's mantle (the subdivision of the earth directly below the crust) and when the continental crust crashes into the oceanic crust it almost always ends up with the oceanic crust sinking beneath the continental crust (how fast it sinks depends on the oceanic crust's temperature; the colder the faster it sinks) and we call this subduction. The opposite of subduction is spreading and spreading occurs when the earth’s crust is stressed so much that giant cracks appear; at these cracking points magma wells up and new crust is formed.

So which direction are each of the continents going today? 100 million years ago North America & Europe formed the continent of Laurentia, however, North America rifted (that means broke off of) Europe and began moving westward. Rifting of contents normally occurs when the continental landmass is so large that it acts like an insolating blanket and heat builds up underneath the continent. North America has been heading westward ever since and it is just now beginning to crash into Siberia (the eastern most part of Siberia is actually on the North American plate). 63 million years ago South America, Africa, Antarctica, the Indian subcontinent, and Australia formed Gondwanaland which is essentially the southern part of Pangea (Pangea was formed when Laurentia and Gondwanaland briefly merged together). Gondwanaland broke up with India rapidly heading northeast (where it eventually hit Asia and formed the Himalayas) while slowly rotating counter clock wise, South America rifted off of Africa heading westward, Africa is very slowly heading northward (thus closing off the straight of Gibraltar and eventually crashing into Europe), Antarctica is rotating slowly clock wise almost exactly around the south pole, and Australia rifted off of Antarica and is now rapidly (Australia is moving the fastest of any continent) northward. Asia forms a special case because it is the youngest of all the continents. Asia is actually an acresionary mass of volcanic arches and old island chains.

[Nubclear]

Care to draw us a really crude map, Oerdin?

[Oerdin]

Originally posted by Odin
California moves up the coast,

California is acutrally on two different plates. All of the land west of the San Andreas fault is on the Pacific plate (an oceanic plate) while everything east of the San Andreas fault is part of the North American plate. The Pacific plate is slowly moving northward relative to the North America plate so that's why we have the right lateral movement along the San Andreas fault.

Interestingly enough there used to be a continous subduction zone from Alaska all the way to central America complete with volcanos and Earthquake zones. About 25 million years ago the spreading center off the California coast got subducted and this "triple junction" is what ended up setting up the strike slip fault system which charactorizes California today (though subduction still occures from Northern California to Alaska and from Central Mexico to Central America).

[Oerdin]

Originally posted by Comrade Tassadar
Care to draw us a really crude map, Oerdin?

Here's a map which shows Pangea and the physics of continential drift. Here's an excellent site which shows the position of the continents in differnt geologic ages so you can watch their movements as time progesses.

[DanS]

How fast is Africa heading toward Europe?

[Oerdin]

Originally posted by mrmitchell
Question: Would an endless rain of nuclear holocaust seriously effect any of the geologic factors that shape the world?

No, it would not. The reason being that the movement of the continents is powered by differences in density and no matter how much we nuked things the relative densities would stay the same.

[Oerdin]

Originally posted by DanS
How fast is Africa heading toward Europe?

If memory serves the northward rate is around 1.2 mm per year. Though I must confess that my tectonics text books are in Sacramento and I am currently in San Diego. To compare the northward rate of Australia is around 15mm per year. At a geologic time scale the continent of Australia is flying.

[Nubclear]

Looking at those maps.....

Australias going to freeze over

[Oerdin]

Australia is acutually heading north at this time. Though in the past it was much closer to the south pole. It's interesting that the world's marsupeals all leave in South America and Australia because the after Africa and India split off those two continents were connected via Antartica. South America has been polluted by animals from North America while Australia has remained pure.

(There are a few exceptions such as Dingo's, wild dogs, which were brought by humans.)

[Nubclear]

But the future maps say Australia is gonna be one with Antarctica

Are you saying it isn't true?

[Victor Galis]

Hmm... so 250 million years from now Pangea will be reformed.

[pchang]

How do you know it will be the last one? Won't it split up and then reform again in another 400 - 500 million years?

[Oerdin]

We have actually have four super continents in the history of the Earth and Pangea is only the most recent and most well known.

Tass: To my memory Australia rifted off of Antarctica and has been heading north ever since. It is stilling heading north as we speak and it is moving faster then any continent on Earth. Eventually it will crash into the Indonesian volcanic archipelago and perhaps even the Philippine archipelago.

[Oerdin]

Originally posted by pchang
How do you know it will be the last one? Won't it split up and then reform again in another 400 - 500 million years?

Megacontinents are a trade off. You see the Earth's surface only has so many places for a continent to go and this leads to continents slamming into one another. The thing is if continents get to large the heat builds up underneath them and this leads to rifting along with spreading.

[Harovan]

Wasn't Italy part of the African plate and the Alps a result of the clash of this plate with the European one?

And btw, the Northern supercontinent was called Laurasia and not Laurentia.

[Oerdin]

Italy is actually what we call a microplate. Meaning it is a small continetal mass which moves as it's own plate. Other microplates such as the mideastern plate and the Central American plate exist.

Laurasia and Laurentia are two different spellings for the same continent. It really depends upon who you speak to and where they are from as to which of the two names are used. In General Americans & Canadians use Laurentia while Europeans use Luarasia.

[Harovan]

Originally posted by Oerdin
Laurasia and Laurentia are two different spellings for the same continent. It really depends upon who you speak to and where they are from as to which of the two names are used. In General Americans & Canadians use Laurentia while Europeans use Luarasia.

Not sure if this is true. This source talks about both Laurasia (wrongly spelled Laurussia there) and Laurentia in a different context.

[Oerdin]

http://www.palaeos.com/Earth/Geography/Laurentia.htm

I'd really have to pull out my old college text books but there were a great many ancient continents which were created and then broken up.

[Gatekeeper]

Fascinating. Asia — which is home to some of humanity's *oldest* nations —*is, geographically, the *youngest* continent. Anyone sense a bit of irony here, or is it just me?

Gatekeeper

[Oerdin]

Most of China existed as a volcanic island arch in the tethese sea. A number of subplates docked in order to form the modern Asian content which is the youngest of the major continents.

P.S. I'm on my second bottle of Pinot Grigio so I hope people will understand any spelling errors.

[CerberusIV]

Supercontinents are believed to form on a regular cycle ~ 500Ma or so. The thought is that the Pacific Ocean is more or less permanent whilst the Atlantic will eventually close up again. Once the oceanic crust flooring the Atlantic gets cold enough it will start to sink beneath Europe/Africa and the Americas, the continents will start to move together again and the ocean will close up.

As the earth cools, the rate of tectonic drift is slowing down.

By the time anything noticeable happens none of us will be around. Of more immediate interest is the likelihood of a magnetic polarity reversal during the next few hundred years. That is going to be very interesting indeed!