I was hiking in my local mountain chain yesterday and got to wondering about what determines the height of mountains. Is there some sort of natural geological maximum elevation mountains can reach?
And along the same lines, during geological history, would there have been mountains that were higher than the Himalayas are now?
This site claims 10 km (about 33,000 feet) as the ceiling, and uses a lot of math to determine that number, but I don’t know how good this analysis really is.
I can’t find a reference now, but I’ve read that the central pangean mountains
Now represented by some very modest mountain ranges, like the Appalachians, were the highest the world has seen. (But have worn down over the ages.)
@QtM If the site is correct, Mauna Kea is pushing the limit because it is 10,203 meters from base to peak, not just the part that got its head above water.
It helps, though, that most of it is underwater. Stone doesn’t float, but it’s still at least somewhat buoyant.
If they get too high they could possibly flip over in the ocean? I know there was some concern in the past about Guam possibly flipping over, due to massive build up there.
I have read that our politicians are closely monitoring that situation. I’d leave the matter in their capable hands.
My understanding is that some soft limits are determined by isostasy, and that if a mountain extends upwards, it has to have a “root” that extends downwards into the crust, and there is a limit to how deep that root can go before it melts at the bottom.
Mountains can still rise above that level if some process is actively pushing them up, but that puts a long-term soft limit.
I’ve heard something similar for the island of Tenerife. It is composed of three different undersea mountains fused together, and possibly some part of it could collapse into the sea. But I might have the wrong Canary island in mind. I would think that there’s just a massive avalanche, not sure what you mean by ‘flipping over’.
In theory, if god made it with the correct materials when he blinked the universe into existence it could extend up into orbit, a natural space elevator.
I’m quite confused. Are you trying to mock people who mock your religious beliefs by mocking religious beliefs yourself? Are you a metamocker?
The Guam bit is a reference to a politician some years back who was worried about the island capsizing if it had too much weight on it. Islands don’t actually work that way.
Not sure about Guam, but if this XKCD poster is accurate, than the ratio of Mauna Kea’s height to width is such that it can’t “fall over”; it’s already lying down. I’d be surprised if other islands had height/width ratios that posed a risk of the entire island toppling over.
The actual Guam remark by Hank Johnson was this:
His remark was preceded by a discussion of the length and width of the island (as a measure of land area), but no mention of altitude or local sea depth - and it was followed by remarks about enviromental degradation. He was not actually addressing the geological instability of the island; rather, it was a facetious commentary regarding a large influx of US military personnel, their dependents, and construction workers. However, because of his lack of any comedic cues while he was speaking, everyone took his remark at face value.
La Palma is the one usually cited. In depth discussion about the mega tsunami possibility at this AGU blog post: Understanding the La Palma mega-landslide hypothesis: part 1 - The Landslide Blog - AGU Blogosphere
The author doesn’t believe in the hypothesis, but nevertheless lays out the evidence for it pro and con.
Thanks. When I heard about this it sounded kind of hokey. It sounded like half the island would just sink into the ocean leaving the other half standing.
Feynman mentions this limit in passing at the 48 minute mark of this interview video. Any excuse to show people that video ;).
On a related note, I’ve always wondered why Earth seems to have such runty mountains; it’s my understanding that many of the other rocky bodies of the solar system - Mars, some of the moons of Jupiter, and possibly Venus - have mountains that make ours look like molehills. I know that’s true for Mars, which is smaller than Earth. I might be wrong on the premise, too, since the only ones I’m sure are huge mountains are on Mars - maybe wherever I heard that other planets/moons also have huge mountains was wrong?
Watch the video clip I posted :).
The mountains are higher because those bodies are smaller than the earth. Lower gravity means that the rock can support a larger mountain before collapsing.
I don’t know how much of a difference it makes but they all have lower gravity than Earth. Erosion is different too: the moon has no wind or rain, Mars has less than we do, and AFAIK Venus doesn’t have frost shattering.
Gravity is the biggest factor. The strength of the materials doesn’t change that much, but the forces on a more massive planet are much higher.