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A nice picture for "how mountains formed" on Earth is due to the motion of tectonic plates. As the plates crash together, mountains may get "pushed upwards". However, a quick look at a map of the tectonic plates on Earth will show that there are some clear examples of significant mountain ranges which do not lie along the tectonic plates. I noticed the Ural mountains first, but even the Appalachian mountains don't appear to be associated with a particular pair of tectonic plates.

Nevertheless, Wikipedia tells me that the Ural mountains formed by the collision of the Laraussa and Kazakhstania continents - so why is there not a plate boundary underneath the Ural mountains?

EDIT: Here are few links with tectonic plate maps, demonstrating that there is no known division between plates at the location of the Ural mountains. Of course, I can't independently verify these, I'm just relying on consistency of unknown sources.

https://www.thoughtco.com/map-of-tectonic-plates-and-their-boundaries-1441098 https://pubs.usgs.gov/gip/99/pdf/gip99_ppt.pdf https://www.learner.org/interactives/dynamicearth/tectonicsmap/ https://earthobservatory.nasa.gov/Features/Tectonics/

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  • $\begingroup$ This is something you could easily look up on google. $\endgroup$ – Eevee Mar 2 '18 at 18:07
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    $\begingroup$ @Imtherealsanic: Wikipedia says what I alluded to in the question: "They were formed during the Uralian orogeny due to the collision of the eastern edge of the supercontinent Laurussia with the young and rheologically weak continent of Kazakhstania," This is the statement I do not understand, and I would like an expert to explain it to me. There is no tectonic boundary there on the maps that I've found. $\endgroup$ – cduston Mar 3 '18 at 15:16
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    $\begingroup$ I am aware of the timescales involved - how could two landmasses move on a single continental plate? While tectonic plates move over the mantle, are there "landmasses" that move on top of the plates (somehow?). Or has the boundary between these two "landmasses" (plates?) been erased over time? $\endgroup$ – cduston Mar 3 '18 at 15:36
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    $\begingroup$ My understanding is that the landmasses are connected to the plates, which is why the wikipedia explanation confuses me; how can two landmasses collide to cause the creation of the Urals if there is no division between the plates at the location of the Urals? I've edited the original question to include links to the maps I am referring to. $\endgroup$ – cduston Mar 3 '18 at 22:01
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    $\begingroup$ (What I mean by "erased") Is it possible that two plates collided and did indeed create the Ural mountains, but then "fused" together to create a single plate - probably what is now called the Euroasian plate. $\endgroup$ – cduston Mar 3 '18 at 22:04
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The Ural mountains are one of the oldest mountain ranges on Earth. They started forming about 300 Ma ago by the subduction of the oceanic crust once attached to the Kazakhstania plate under the ancient Laurussia continent. A subduction process that finished about 240 Ma ago.

The tectonic plates are far from fixed, some of them disappear over time other new ones can form, they can move, merge and split. The ones involved in the formation of the Ural mountains are not currently considered tectonic plates by themselves, they are part of the Eurasian plate now.

To understand the scale and magnitud of the changes in the tectonic configuration I strongly recommend you to carefully look at the wonderful animation produced by Christopher Scotese, as part of the PALEOMAP Project. To find the answer to your question, I would recommend you to pay special attention starting on minute 3:10, by following the area that I've highlighted with red lines in the following screenshot of that video: enter image description here

You will see that 416 Ma ago and before there was an active subduction boundary there inside the red polygon. So mountains were getting formed, the ocean in front of that boundary closed-up and disappear about ~240 Ma ago, giving the final push for the formation of a mountain range, that, if you follow it carefully, corresponds to the Ural mountains we know today.

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    $\begingroup$ oh man I wish that video had a narrator to explain the line color and point out significant events - but it's great, and a perfect answer. $\endgroup$ – cduston Mar 4 '18 at 0:15

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