I find the concept of folding a little fantastical

[Hall]

All the Geography/Geomorphology books I have come across with, simply write “Himalayas are fold mountains”, “folding is the warping of land due to tectonic motions”, “earth surface is like a dough which can be warped by compressing forces”. I mean, every time I fell on ground I never felt anything like a dough, but a hard, damage-causing rigid surface. I really don’t know why folding is never explained in detail, only folding landforms are described.

Can you please explain how does warping of earth’s crust occurs? Were the tough rocks of Himalayas like a dough?

 

[256bits]

So you took the analogy seriously.

earth surface is like a dough which can be warped by compressing forces

Under extreme pressure, 'hard rock' becomes plastic.

 

[BillTre]

So you took the analogy seriously.

Under extreme pressure, 'hard rock' becomes plastic.

Extreme pressure includes going deeper under ground.
Things also tend to be hotter there.

You might also want to note that these are slow motions compared to your impacts with the ground.
A fast rate of continental drift might be 16 cm/year. This is less than .5 mm/day. Most would tectonic movements would be slower.

The resulting compression of horizontal layers can result in folding.
There should not be any doubt that these iknds of movements and the resulting compressions occur. They have been observed.

 

[Hall]

There should not be any doubt that these iknds of movements and the resulting compressions occur. They have been observed.

Can you direct me to resources where I can read about those observations?

 

[Hall]

'hard rock' becomes plastic.

Thanks for using another textbook language :). Why do books refer the whole tectonic plates as rocks? Are Himalayas rocks? I mean, it is hard for me to imagine a rock bigger than this one

 

[Baluncore]

I mean, it is hard for me to imagine a rock bigger than this one

This rock is a little bigger, and that is only the bit that sticks out of the ground.
https://en.wikipedia.org/wiki/Uluru
Another bit of the same rock outcrops 25 km west of that.
https://en.wikipedia.org/wiki/Kata_Tjuta

 

[Hall]

This rock is a little bigger, and that is only the bit that sticks out of the ground.
https://en.wikipedia.org/wiki/Uluru
Another bit of the same rock outcrops 25 km west of that.
https://en.wikipedia.org/wiki/Kata_Tjuta

Thanks.

If that is only a bit sticking out of the ground, then is it a faulting or upliftment?

 

[Baluncore]

If that is only a bit sticking out of the ground, then is it a faulting or upliftment?

The rock sticks up out of a flat plain because the rock was unusually hard and had few cracks or joints. Over a very long time, the surrounding plain with many cracks and joints has been weathered and eroded. All the extra material has blown away in the wind or been washed down the rivers.

 

[pinball1970]

Thanks.

If that is only a bit sticking out of the ground, then is it a faulting or upliftment?

Some nice graphics in this link. https://www.nationalgeographic.com/...t-everest-can-grow-and-shrink-plate-tectonics

 

[BillTre]

Can you direct me to resources where I can read about those observations?

Here is a wikipedia article that probably addresses a lot of the issues you have.

 

[Mark44]

Why do books refer the whole tectonic plates as rocks? Are Himalayas rocks? I mean, it is hard for me to imagine a rock bigger than this one

Tectonic plates are made up of rock (not rocks, which are individual chunks of some bedrock). The Himalayas are made up in large part by limestone, a type of sedimentary rock that forms from the hard shells of sea creatures. The Himalayas also include igneous rock that is produced by volcanic activity, as well as metamorphic rock that is pre-existing rock that is altered by heat and pressure.

The rock in the picture you posted is a small part of a much larger bedrock layer. As already mentioned, softer rock is eroded away, leaving harder rock behind. Also, some types of rock, such as granite, is pretty hard, but can fracture, so large bodies of rock can become chunks like the one you see in the picture. If I had to guess, I'd say that the balancing rock is partially made up of sandstone of some type, based on the strata that appear in the rock and the one it's sitting on, but it looks like it has a cap of some darker rock on top. Perhaps the darker rock is something harder that protected much of the rock sitting below it, but wind appears to have eroded the base of the balanced rock to a thin supporting column.

 

[Tom.G]

You can probably find more information (or at least images) than you want at:
http://portal.gplates.org/

(I keep a link to the site on my desktop for the occassional neighbor that has never heard of such a crazy idea.)

Have Fun!
Tom

 

[snorkack]

Extreme pressure includes going deeper under ground.
Things also tend to be hotter there.

You might also want to note that these are slow motions compared to your impacts with the ground.
A fast rate of continental drift might be 16 cm/year. This is less than .5 mm/day. Most would tectonic movements would be slower.

The resulting compression of horizontal layers can result in folding.
There should not be any doubt that these iknds of movements and the resulting compressions occur. They have been observed.

Slower on average.
On 25th of April, 2015, Nepal moved south. Previously, Nepal moved south on 15th of January, 1934.
How much did Nepal move south in 30 seconds on 25th of April, 2015 compared to the total movement in the 81 years between 1934 and 2015?
Did Nepal fault on 25th of April, or did Nepal fold?

 

[Hall]

@Tom.G This has solved many doubts of mine.

The Himalayas ^^^ are not that high, it's I who is very small. Folding cause just a bit in increase of height, it is just that 8km is too much for me. The above image really explains folding than a whole book on it.

 

[Hall]

Next doubt: Are Himalayas on Indian plate or Eurasian plate? Are these two plates touching each other only on the crust or some high landforms on Eurasian plate is also touching something on Indian plate?

The doubt has quite its merit, because plates are not simply like this:

they have things on top of them, maybe like this

 

[BillTre]

What I have read is that the Indian plate has to some extent not simply subducted down when it ran into the Eurasian plate, but kind of slid under it, making a double thick layer of crust in some areas.
For reasons unknown to me.

 

[snorkack]

What I have read is that the Indian plate has to some extent not simply subducted down when it ran into the Eurasian plate, but kind of slid under it, making a double thick layer of crust in some areas.
For reasons unknown to me.

The reasons are quite simple. Continental plates are not easy to just destroy or subduct, so when they are pressed together, they fail by low angle thrust faulting.
The part I do not catch is how faulting turns into folding...
https://en.wikipedia.org/wiki/Glarus_thrust#/media/File:Glarus_Thrust_Fault_in_Switzerland_2018.jpg
Well, this is a frontal view of a thrust fault, not side view.
I am not sure if the middle Tschingelhörner are connected to a continuous thrust sheet behind them. The small teeth on the right surely aren´t?
When a big earthquake comes in Switzerland like the Nepal one of 2015, and the Glarus Thrust moves the upper unit of Tschingelhörner a few metres towards the viewer relative to the lower unit, how is it going to fold? I can see the thus formed overhang of the cliff collapsing in rockslides down the cliff and into the talus slope, but it would not be a fold.