How tall is the tallest possible mountain on Earth? Is Everest close to this limit, or could a mountain grow higher still? What about on land vs. underwater?
I can think of two factors that would limit the height of a mountain. First is the scalability of the strength of materials. If the mountain were to grow too big, it would not be able to support it’s own weight and crumble. Second would be the ability of the Earth’s crust to support the weight of the mountain. A mountain that were too heavy would sink into the ground, so to speak. I’m not a geologist so I wouldn’t begin to know how to put numbers to these and quantify a maximum height, nor if these ideas are even reasonable.
What other limiting factors would there be? Would the weight of water influence the height of an undersea mountain? I’m also guessing the rate of upthrust vs. the rate of erosion would limit how close a real-world mountain could get to the limit, but I don’t think it would come into play as far as the value of this hypothetical absolute tallest mountain.
I think more important than the strength of the materials is the material’s natural angle of fall, I can’t remember the term, but it just means that even if it crumbles, it’s still a mountain, just a really shallow slope.
Look at Olympus Mons on Mars. It’s pretty shallow slope but much higher than anything we have on Earth.
The spin of the Earth would limit the weight concentrated on one side of it, I think.
Mountains actually have “roots” that extend down into the mantle, and therefore are not entirely dependant upon the surrounding crust for support; they are also bouyed up by the mantle in the same way a ship is on the ocean. The size of these roots are generally proportional to the mountain itself, as they are the result of the same orogenic forces. When plates collide, as in the Himalayas, some material gets pushed upward (Everest, etc.) and some downward (the “root” of Everest, etc). I imagine a mountain’s height is limited only by the rate of erosion vs. rate of upthrust and the angle of repose for the material is it composed of. Theoretically, I suppose a mountain could keep getting taller as long as the plates pushing it up still had rock to shove together. Eventually, the root of the range might hit a denser layer, but I’m not sure what might happen then.
Science ficiton novelist Kim Stanley Robinson is not a solid scientific source, but he widely acknowledged for high levels of scientific accuracy in his works. In a short story that appears in The Martians, one of his characters claims that Olympus Mons is at the limit of the highest possible mountain that can exist on Mars, without collapsing under its own weight. Since Earth has stronger gravity than Mars, I would guess that the weight limit is lower here.
Of course the Indian subcontinent is still hurtling northward into Asia, pushing the Himalayas up by more than a foot per century. So all you need to do is hang out for a few eons and you’ll see how high a mountain can get.
I remember seeing a TV documentary that talke about the difference between mountains on Earth, and the much taller mountains on Venus. Scientists hypothesize (and have experimental evidence) that the chief factor is the humidity. Earth mountains get worn away by water, and the rock has more water content, so over geological time scales the substance of the mountain sort of melts. On Venus, with no appreciable humidity, mountains grow much higher, and they are much more angular.
I guess to really get the maximum theoretical height of an Earth mountain, you would have to find the maximum theoretical collision of tectonic plates. The larger the collision, the larger the mountain.
IIRC, the Himilayas are still growing.
And I guess, theoretically, the Earth’s climate could drastically change, and so eventually you could have Venus-style mountains on Earth.
Everyone always cites Everest as the tallest mountain in the world which is a mistake. Everest is the highest point on land on earth but it is not the tallest mountain.
The record for the tallest mountain in the world goes to Mauna Kea in Hawaii. At 13,795’ above sea level it doesn’t seem like it till you consider there is something like 16,000’ more of it below sea level. So, at ~40,000 feet tall it has Everest beat by a healthy 11,000 feet (give or take…I had a hard time getting a specific number for Mauna Kea’s height from the base but it definitely has Everest beat easily).
If you look at Olympus Mons it is staggeringly wide. Unlike an upthrust mountain (Everest) I am not sure there is a real limit to how big a volcano could get as it keeps building itself up as long as it keeps erupting. That said Mauna Kea is actually decreasing in height as it collapses (slowly) under its own weight and has not erupted to build itself up in something like 10,000 years.
My favorite sci-fi mountain is Fist-of-God from Larry Niven’s Ringworld. That mountain was so high it stuck up out of the atmosphere (which was a good thing as otherwise Ringworld’s atmosphere would have leaked out the hole).
As a general rule of thumb, if there exists a theoretical maximum for something, and you have a large sample of those things, it’s probably a safe bet that the largest of those things in your sample is pretty close to the maximum. And it happens that there is a theoretical maximum for mountains: Pile on too much mass, and it’ll sink faster than you can pile it on. Ergo, it is reasonable to deduce that Everest is probably close to the limit.
jawdirk, you’re probably thinking of Mars, not Venus. Neither one has much water, but Venus has sulfuric acid, which I would also imagine is fairly effective at erosion. Nor have I ever heard that Venus has mountains higher than Earth’s. Mars does definitely have higher mountains than does Earth, but that’s usually attributed to the lower surface gravity on Mars.
Mauna Kea is definitely taller than Everest but a good bit.
Mauna Loa is not as tall as Mauna Kea but it is more massive than either Everest or Mauna Kea. I get Mauna Loa at ~40,000 km[sup]3[/sup] (cite and Mt. Everest at ~37,295 km[sup]3[/sup] (cite [albeit not a very good cite I think but all I could find]).
Further Mt. Everest is still growing at a rate of 2.4 in/yr. (cite ). I am not sure if Mauna Loa is still growing as it is still pushing out lava (one of the most active volcanoes on earth) but I do not know if it sinks as fast as it grows now.
Where will it end? I have no clue but it would seem the limit is not met yet. Just because Mt. Everest is the highest above sea level today I do not think that necessarily indicates the limit by saying if we could have bigger mountains we’d see them. It does not follow because Everest has not been growing since the beginning of the earth. It has only been growing since India smacked into Asia. Thus the best chance for a really tall mountain has not had time to fulfill its promise yet.
Venus has plate active plate tectonics and thus is comparable to Earth, unlike Mars which is a dead planet. Venus is baked dry, and the moisture is more important geologically than the other constituents, according to the documentary I saw. Here it says that Earth has .02 % H2O, while Venus has .003%.
What if we measured Mt. Everest from the sea floor of the Indian Ocean to its peak?
Since we’re talking really, really big mountains here, neither one really seems to be all that big.