Birth of Earth

[EndLightEnd]

Geologyrocks, according to the sea floor map, how is it exactly that India moved independently from the east coast of Africa all the way up to south Asia, across an oceanic trench, to crash into asia to form the mountains which cannot be explained ANY other way (according to plate tectonics)?

Im confused how a continent can move across a trench which is responsible for the pushing.

When did India “crash” into Eurasia, while the southern continents were a further 2000 miles to the south? That’s where the southern continents were 50 million years ago. Or while 4 continents were at the South Pole did India independently voyage north for 2500 miles? All by itself?

And speaking of physics … physics say every action has an equal and opposite re-action, well we have established it’s the oceanic plate that moves. The continental India is the body of the thing. Think of it like a Volkswagen Beatle crashing into a truck. No matter how that truck crumples … it’s nothing compared to how crushed the Volkswagen would be.

The same thing is true of India. India would be one vast mountain range … it’s not.
the Eurasian mountains are far too gigantic and extensive to be crumpled by puny India.

Look closer. Examine the north of India. This is an impacting body. Yet, the top of it is extensive flatland. So flat, in fact, that it looks almost stretched out. How can this be an impacting body?

 

[EndLightEnd]

Look how South America fits perfectly into Africa. Easy enough to recognize . They said that a child could see it. But here’s the thing.

If you settle South America to Africa, in the north there is a 25 degree split between the two. They do not fit! If you try to fit downward coasts, there is a 25 degree split at the top.

There is only one way these two continents will fit together properly.

If you make a globe 50% smaller … and re-curve these two continents on to that globe…

They fit perfectly!

 

[geologyrocks]

Geologyrocks, according to the sea floor map, how is it exactly that India moved independently from the east coast of Africa all the way up to south Asia, across an oceanic trench, to crash into asia to form the mountains which cannot be explained ANY other way (according to plate tectonics)?

Im confused how a continent can move across a trench which is responsible for the pushing.

When did India “crash” into Eurasia, while the southern continents were a further 2000 miles to the south? That’s where the southern continents were 50 million years ago. Or while 4 continents were at the South Pole did India independently voyage north for 2500 miles? All by itself?

And speaking of physics … physics say every action has an equal and opposite re-action, well we have established it’s the oceanic plate that moves. The continental India is the body of the thing. Think of it like a Volkswagen Beatle crashing into a truck. No matter how that truck crumples … it’s nothing compared to how crushed the Volkswagen would be.

The same thing is true of India. India would be one vast mountain range … it’s not.
the Eurasian mountains are far too gigantic and extensive to be crumpled by puny India.

Look closer. Examine the north of India. This is an impacting body. Yet, the top of it is extensive flatland. So flat, in fact, that it looks almost stretched out. How can this be an impacting body?

I'm assuming that you accept then that there are mountain ranges older than 200 Ma then?

To move onto your next point then...

A few things for you to consider when carrying out plat reconstructions (this applies to your next post also). First, plates do not simply translate (i.e. it's not a linear motion) - their motion is a rotation around an Euler pole (have a google for this). Second, it's not the visible bit of continent that forms the "continental plate" only - it's the continental shelf too.

When applying these to India, the second point is the most important. Se this reconstruction: http://www.scotese.com/0652d.htm
See how big the northern continental shelf is on India? That's now the Himalayas. At the same time, you do not simply crumple "upwards", if you see what I mean. There are sedimentary basins associated with continental collisions - the fore and back-arc basins. The fore-arc basin for the Himalayas is now filled with sediment from the Himalayas - hence it's very flat. This is now Bangladesh. The sediment pile here is so think it's metamorphic rocks at the bottom of the pile...Saying all this, India is pretty mountainous!

Looking at the sea-floor map (http://www.ngdc.noaa.gov/mgg/image/crustageposter.gif), do you see those two very long transform faults running north-south in the Indian ocean? That's the evidence that India moved quickly northwards from Antarctica

As I recommended in earlier posts - go and read up on this. Global Tectonics by Keary and Vine is a good start. All of what you ask is explained in textbooks for undergrad level...

 

[geologyrocks]

Look how South America fits perfectly into Africa. Easy enough to recognize . They said that a child could see it. But here’s the thing.

If you settle South America to Africa, in the north there is a 25 degree split between the two. They do not fit! If you try to fit downward coasts, there is a 25 degree split at the top.

There is only one way these two continents will fit together properly.

If you make a globe 50% smaller … and re-curve these two continents on to that globe…

They fit perfectly!

Look up Euler Pole rotation and make sure you use the continental shelf margin, not the coastline...

Also remember, the Atlantic did not open at the same time. The central Atlantic was first, then the south Atlantic, finally the north Atlantic opened about 65Ma...

 

[OilIsMastery]

For Pangea, in the UK at least, we have the Variscan Orogeny. This is most visible in Devon causing some spectacular folds: http://www.geologyrocks.co.uk/images/cheveron_folding_2

Clearly, the further back in time you go, the less evidence there is for past events, but there is evidence for past mountain building - even that when Pangea formed.

Pangea is a myth. Wegener was right about continental drift but wrong about constant size Earth.

There was a supercontinent on a smaller Earth 200 million years ago but there was no Panthalassa or Tethys Ocean. Can you imagine how ridiculous that planet would look?

 

[EndLightEnd]

A few things for you to consider when carrying out plat reconstructions (this applies to your next post also). First, plates do not simply translate (i.e. it's not a linear motion) - their motion is a rotation around an Euler pole (have a google for this). Second, it's not the visible bit of continent that forms the "continental plate" only - it's the continental shelf too.

So how did India move across the spreading zone between africa (where india used to be) and where it is now?

 

[D H]

What makes you think it did?

 

[geologyrocks]

So how did India move across the spreading zone between africa (where india used to be) and where it is now?

It didn't. I'm not sure where you're getting the idea it did!? It was moved by the spreading ridge:
http://www.scotese.com/indianim.htm

 

[EndLightEnd]

If it were one time connected to Africa it would have been on the OTHER side of the spreading ridge your claiming pushed it into asia. This can be seen by looking at a map of the sea floor.

 

[OilIsMastery]

If subduction exists, exactly what has been subducted and where? What fictional continents have been subducted?

 

[D H]

If it were one time connected to Africa it would have been on the OTHER side of the spreading ridge your claiming pushed it into asia. This can be seen by looking at a map of the sea floor.

Wrong. The rift zone that separates India from Africa has not always existed. That rift zone split India from Africa; it formed when India and Africa were connected.

The exact same thing is happening today in the East African Rift Valley and the Baikal Rift Zone.

 

[geologyrocks]

If it were one time connected to Africa it would have been on the OTHER side of the spreading ridge your claiming pushed it into asia. This can be seen by looking at a map of the sea floor.

Then you're looking at a different map to the one you posted! The spreading ridge between India and Africa would push them apart. Which is exactly what happened. Did you watch the animation I posted? It's very clear there!

 

[Trippy]

If subduction exists, exactly what has been subducted and where? What fictional continents have been subducted?

You've already had this explained to you several times now - continental crust doesn't tend to get subducted (easily) because the oceanic crust is denser, so it's easier for the oceanic crust to slide under the continental crust (also, the oceani crust is thinner - one might say that when a vehicle hits a person above their center of mass, that the person is subducted under the car, a poor analogy in many respects, but never the less).

 

[Trippy]

Pangea is a myth. Wegener was right about continental drift but wrong about constant size Earth.

There was a supercontinent on a smaller Earth 200 million years ago but there was no Panthalassa or Tethys Ocean. Can you imagine how ridiculous that planet would look?

And of course you can explain the presence of Oceanic crust as much as 6 times older than this that has been preserved as parts of continents?

 

[Trippy]

Look how South America fits perfectly into Africa. Easy enough to recognize . They said that a child could see it. But here’s the thing.

If you settle South America to Africa, in the north there is a 25 degree split between the two. They do not fit! If you try to fit downward coasts, there is a 25 degree split at the top.

There is only one way these two continents will fit together properly.

If you make a globe 50% smaller … and re-curve these two continents on to that globe…

They fit perfectly!

You mean quite aside from the fact that because of the way these things work, the plates effectively rotate when they move (something to do with sliding around the surface of a sphere) - a statement that's born out by the GPS measurements, which I have posted a map of elsewhere, which indicate that North America is in fact rotating significantly, so if you rotate, and then translate North America, it fits.

This is also born out by your own map, which, if you look at it, indicates that the oceanic crust off North America is older than the oceanice crust off South America.

 

[OilIsMastery]

You've already had this explained to you several times now - continental crust doesn't tend to get subducted (easily) because the oceanic crust is denser, so it's easier for the oceanic crust to slide under the continental crust (also, the oceani crust is thinner - one might say that when a vehicle hits a person above their center of mass, that the person is subducted under the car, a poor analogy in many respects, but never the less).

You didn't answer either question. What mythical continents are you saying were subducted and where were they subducted? Mu?

 

[geologyrocks]

If subduction exists, exactly what has been subducted and where?

Oceanic crust is subducted. Even in continental/continental collisions, it's the oceanic plate that is subducted until the two continental plates actually collide.

Current zones are around the Pacific ring (all up the coast of South America, North America, Bearing Straits, and down the coast of Asia, PNG and New Zealand), a small zone in the Caribbean, between Africa and Europe, between India and Asia, are the main ones.

These are ocean/ocean, ocean/continental and continental/continental collisions and show different features.

Past zones (that I know of!) can be observed in details near the England/Scotland border - this is Silurian/Ordovician in age. There are others, but my knowledge of them is limited.

What fictional continents have been subducted?

None. Continents are eroded into the ocean basins. The sediments are then subducted or they become part of the accretionary wedge observed at many subduction trenches. This is also when ophiolites are formed too.

 

[OilIsMastery]

Current zones are around the Pacific ring (all up the coast of South America, North America, Bearing Straits, and down the coast of Asia, PNG and New Zealand), a small zone in the Caribbean, between Africa and Europe, between India and Asia, are the main ones.

Unfortunately for plate tectonics it's impossible that the Ring of Fire is subducting because it's actually spreading at the East Pacific Rise. Do you know how to tell time?

 

[geologyrocks]

Unfortunately for plate tectonics it's impossible that the Ring of Fire is subducting because it's actually spreading at the East Pacific Rise. Do you know how to tell time?

Personal insults aside...

Not sure what your point is? The EPR is a spreading ridge, whilst the subduction goes on around the edge. Some parts of the spreading ridge have been subducted. This formed the San Andres fault (as the complex motions associated with the subduction of the ridge lead to a conservation margin along that region) - this is a complex situation. As I've suggest previously, Keary and Vine's Global Tectonics has some more info on this.

http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/Maps/map_plate_tectonics_world.html

On the map linked to above the EPR transforms into the San Andres, before coming back into a spreading ridge in the North East of the USA - the ridge between was subducted. It's a lot more complex than my simple 20 word explanation, but we spend an entire 2 hour practical on this where I teach, so it's hardly surprising I can't put the idea across in a short forum post...

 

[OilIsMastery]

The EPR is a spreading ridge, whilst the subduction goes on around the edge. Some parts of the spreading ridge have been subducted.

Is the Nazca plate spreading or subducting? You can't have it both ways.