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I'm interested in the limiting factors on the height of mountains. There is a very good explanation at https://www.quora.com/How-tall-can-a-mountain-become-on-Earth-Neil-deGrasse-Tyson-says-Mount-Everest-is-about-as-tall-as-a-mountain-on-Earth-can-grow-%E2%80%9D-but-Mauna-Kea-is-significantly-taller-about-15-than-Everest

The actual lithospheric limit to mountain height averages about half the height of Everest, which is why Fourteeners are so famous in Colorado. Mountains that exceed this limit have local geologic circumstances that make their height possible, e.g. stronger or denser rocks. In the case of Everest and the Himalayas, you have a geologic situation that is very rare in Earth history. The Indian plate is ramming into the Eurasian plate with such force that instead of just wrinkling the crust on either side into mountain ranges it has actually succeeded in lifting the Eurasian plate up on top. So the Himalayas have double the thickness of the average continental plate, thus double the mountain height that would be considered "normal".

That seems to make perfect sense, providing a logical explanation for why the Himalayas and Rockies are both the height they are.

But what about the Andes? Chimborazo 6268 m, Cotopaxi 5897 m, Aconcagua 6962 m, all considerably higher than the 14,000 feet (4270 m) suggested to be the normal limit. And this is not a case of two continental plates colliding. It's a continental plate and an oceanic plate, so the explanation that applies to the Himalayas cannot apply here.

How do the Andes manage to be as tall as they are?

rwallace
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  • Does this answer your question? How high can a mountain possibly get? –  May 13 '21 at 19:25
  • @Universal_learner No. That derives an order of magnitude estimate from the basic properties of the materials, but says nothing about the quoted argument regarding particular mountain ranges, or why the Andes appear to be an exception. – rwallace May 13 '21 at 19:32
  • @Earthworm I don't know where the Quora poster got it from, but I got it from the Quora post. The argument made by that post, sounds plausible, but I'm not a geologist; is it actually incorrect? And I would definitely like to know how the situation differs when mountains are above a subduction zone. – rwallace May 13 '21 at 20:23
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    https://doi.org/10.1126/science.1148615 – Gimelist May 14 '21 at 05:09
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    I believe the mentioned limit is not a thing. Looks like subduction of the Nazca Plate is not uniform, flat subduction in the center as well as steep subduction north and south, as marked by surface volcanism, play a role. –  May 14 '21 at 14:00
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    Even a plume may be involved https://www.sciencedirect.com/science/article/abs/pii/S1342937X17301211. "She keeps me hot. Like a boiling pot". The earth of course ! :-) –  May 14 '21 at 17:39
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    @Gimelist's link as full text: http://geomorphology.sese.asu.edu/Papers/Garzione_etal_Science2008.pdf Note it is about the central part of the Andes. –  May 16 '21 at 14:08
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    I do not understand who is saying what, but the original lectures from deGrasse Tyson can be found here: http://www.infocobuild.com/education/learn-through-videos/astronomy/my-favorite-universe.html – EarlGrey May 19 '21 at 08:42

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