It seems like the headline should be "Why Aren't Mountains Higher?" If I'm reading it right, once mountains hit an certain height, the erosion increases unpredictably, meaning height is reduced beyond what is expected.
I theorize that there are two factors: First glaciers are efficient at gnawing at mountains, and second rock is brittle therefore mountains tend to set in the timespans of millenia even if there are no landslides. The second one might be the one that is unpredictable.
In Switzerland there's a tiny town, Brinzauls, which is setting as a whole together with the slope it sits on about three or six feet a year, because in the depth of a few hundred feet there's water flowing through the cracks of the bedrock. There are plans to bore a tunnel along the water-carrying stratum to drain it to stop the movement downwards.
This is just an example of one of the many things that might happen to crop down mountains.
The setting movement is unpredictable because it also depends on the climate. In oceanic climates water could quite literally be dissolving mountains from below.
It would be really interesting to feed a csv with all of the various attributes into an ML algorithm and see if there are any statistical patterns.
I bet a lot of the 'noise' could be accounted for by the meteorology of the surrounding area. It's interesting that all of the worlds highest peaks are fairly close to the equator. Of course, they are all in the same mountain range, which leaves more variables to rule out.
"The researchers analyzed samples from a broad range of mountain landscapes across the tropics, including Venezuela, Brazil, Guatemala, Costa Rica and Taiwan, controlling for rock type and climate conditions to assess parallel comparisons. They found that after mountains reach a certain elevation, channels between mountains suddenly become extremely sensitive to subtle changes in their inclines, thereby limiting the height of the mountains above. They added data from hundreds of mountain ranges worldwide and found they followed a similar pattern: the height, or relief, of the landscape is capped after crossing a threshold driven by channel steepness."
Could someone walk through this pattern in simplified English? I'm not making heads nor tails of the article.
In short, glaciation & associated erosion grows significantly more aggressive with altitude, creating a sort of asymptotic limit to the height of a mountain.
"The researchers looked at samples from a big number of mountain landscapes [...], comparing their rock types and climate conditions. They found that once mountains pass a specific height, the channels [they mean the area between mountain peaks/ridgelines, basically the path e.g. a glacier "rides" on] become very sensitive to even the smallest changes in their steepness, and that limits the heights of the mountains around them. After adding more data from hundreds of mountain ranges, they could confirm this pattern, that mountain height is limited once its channel's steepness crosses a certain value."
Not sure if I understood "mountain channel" correctly, I don't know much about geology, please correct me if I'm wrong.
EDIT: Think I got "channel" correct though, there's e.g. the English Channel, if you imagine it without water, England and France could be seen like mountains.
I seem to remember reading somewhere recently - and, annoyingly, I can't find it so have no idea whether it was a "reputable" source - that gravity itself imposes a hard limit on the maximum height of mountains. I guess it makes sense given that the larger a mass in space is, the more gravity forces it into a spherical configuration. Still, happy to be told I'm wrong.
Probably not correct since the earth is pear shaped not spherical, and the size of mountains are quite small relative to the earth's curvature. However from the article erosion of mountains seems to be impacted by water, limiting height, so on a smaller similar planet by material and water composition it would stand to reason that force of water given the same mass would be less so perhaps mountains would erode more slowly relative to continental drift and therefore be higher.
> Probably not correct since the earth is pear shaped not spherical […]
What!? What kind of pears are you eating? Do you mean “Egg Shaped”?
EDIT: I think I found the answer myself [1]; @OnlineCourage is probably referring to Seckel or Comice pears. All my life I have eaten either Concorde, Barlett or Bosc pears, but I just remembered that I also found Asian pears in many Chinese supermarkets. OP’s comment freaked out a little bit thinking they see Earth as a Concorde pear.
I was reading about extraterrestrial mountains once, and what I retained was that there aren't any mountains on other planets/moons that are really amazingly higher than earth. By which I would infer that water erosion probably isn't the overwhelming limiting factor.
"The highest mountain on Mars is also the highest mountain and volcano in the entire solar system. It is called Olympus Mons and is 16 miles (24 kilometers) high which makes it about three times higher than Mt. Everest"
My knowlege is old, but iirc I think the reason for Martian mountains being (potentially) higher than earth is the the rock is physically stronger due to lower water content. On earth, the water that eventually makes its way into rocks reduces it's strength, but, on Mars, the relative lack of water makes the rocks physically stronger.
1. You're telling me what I mean by "really amazingly higher"? Well, you don't get to do that. In my opinion, the scarp/cliff around Olympus Mons doesn't count, and disregarding that, it's less than 40% higher than from Mauna Kea/Loa to the seafloor. Frankly, a mountain would have to be well over double earth's highest base-to-peak to be "really amazing" to me. Ten times would really be "really amazing".
2. There's a Wikipedia page on the subject of tallest mountains in the solar system and it says the current leader is (probably) Rheasilvia on Vesta.
Yes, mountains and continents sink into the mantle due to their weight.
Although I can't access the paywalled article, I believe they show it's related to "channel steepness", which is caused by river erosion - perhaps implying mountains could be higher where there are no rivers?
You mean where there is no rain? I’m not sure if there are any terrestrial mountains that don’t get significant precipitation on geological time scales because the topography of mountains themselves causes precipitation of moisture passing over them.
Ice itself is a potent eroder of mountains, but with regard to aridity, both the northern Himalayas and parts of the Chilean/Argentinian Andes are in arid regions - though not arid enough for them to be ice-free, at least for now.
They can have caves and such. Granite and I believe also sandstone tends to be totally solid, but limestone tends to form extensive cave networks from water seeping through the rock. Basalt can also have caves from anciet magma chambers but I don't think those usually lend themselves to human exploration.
Surely covered in the article (paywalled) or literature, but sounds similar to a critical angle of reposehttps://wikipedia.org/wiki/Angle_of_repose where a pile of sand subsides if too steep.
Not applicable to hard rock (non-granular), but a river bank profile with erosion due to flow granular particles, may behave as if granular.
The question is why are they so high if there are limiting factors previously not fully accounted for within the current models. The folks from the Electric Universe paradigm have an alternative model that can explain some of the features "standard" geology may struggle with. I think this might be a good example of one of those.
"How could the process of fossilization [of sand dunes into mountains] be imagined? A dune of loose conglomerate can not simply sink into the earth, be transformed by penetrating liquid magma, and come back to the surface as rock, while the typical dune structure and shape is maintained. The process of fossilization must therefore take place at the surface and it must happen quickly. This is where electricity comes into play. On one hand there is the possibility of melting and solidification, when electricity is introduced through the top of the mountain. On the other hand, it may be a direct electrical conversion. Experiments [Steinbacher 2011, 586] have shown that it is entirely possible to transform dust and soil electrically into different types of rocks. The process first melts the material mixture. Then crystals of different size and composition form. Upon further exposure to electricity, they begin to melt itself. Essential parameters are the composition of the material, current and voltage, and the exposure time."
> The process of fossilization must therefore take place at the surface and it must happen quickly.
> Essential parameters are the composition of the material, current and voltage, and the exposure time.
Is this all trying to say that mountains are just fossilized sand? That is certainly a .. novel... theory of geology.
Fossilization of organic matter generally takes about 10k years, give or take. Fossil is a word that tends to encompass a lot of things though, so it depends.
Still, the amps that you'd have to pump through a dune to get it all to melt/solidify would be astonishing. Think a constant lightening bolt for years on end. Most sands are insulators afterall.
