What would be the conditions of a planet for it to, over the years, form an extreme amount of mountains all across the planet. Not like a ball of spikes, just extremely mountainous.

I still want this planet to be stable and inhabitable by the time humanity inhabits it. So it can't be constantly wreaked by massive Earthquakes or such after a few billion year period after the planets formation.

How would these two traits be able to come to be, scientifically.

  • 3
    $\begingroup$ Hi, Zoey. Mountains come about from high tectonic movement, vulcanism, and meteor impacts. Tectonics require vast periods of time. Volcanoes can build an island in a day. Meteors are basically instantaneous. Do you have a specific question to ask? Why do you need to rationalize mountains on your world? Please remember (a) you're only allowed to ask one question and (b) if you can imagine a book as an answer (which is the case here), your question is out of scope on the site. See the help center for more info. $\endgroup$
    – JBH
    Feb 25 at 18:09
  • $\begingroup$ I meant more so what traits can be put together to make it more mountainous than usual. Like tectonic activity sure, but what specific aspects of tectonic activity can be altered, like plate size or such, can make it form a bunch of mountains over the early years of the planet. And the reason for needing to rationalize it is I like having explanations for these things in order to make the world more in-depth and well constructed. $\endgroup$
    – Zoey
    Feb 25 at 18:33
  • $\begingroup$ @Zoey why not just ask “If I have many small tectonic plates fractured across my planet, what general conditions are needed to cause them to shift and cover the globe with mountain ranges?” That’s one question. $\endgroup$
    – Vogon Poet
    Feb 25 at 22:15
  • $\begingroup$ There would be lakes and plains. I just want it to be far more mountainous than Earth. Maybe most of it would be mountains with occasional plains or bodies of water. Thinking around Earth size mountains, if it is possible to be extremely mountainous and still have large mountains. $\endgroup$
    – Zoey
    Feb 25 at 22:19
  • $\begingroup$ @VogonPoet But I know that having them be too small would lead to the mountains just being tiny and barely count as mountains. $\endgroup$
    – Zoey
    Feb 25 at 22:20

4 Answers 4


Take what works and tweak it slightly

Earth already has vast mountanous areas such as the Andes, the Alps, and the Himalayas, without being an unlivable hellscape of earthquakes and volcanism. So make your planet very Earth-like with just three adjustments.

Lower gravity

Mountains sink into the ground very slowly over the course of millions of years due to gravity. It also determines their maximum height. If it's lower, then they would sink slower and be taller. You can change the gravity very slightly, so that your world remains as Earth-like as possible.

Thinner atmosphere

The atmosphere of a planet erodes its mountains, so having a thinner one means erosion would be slower. Again, you can change it slightly, so that your world is Earth-like.

More continental fragments

You can have your continent be made up of several smaller plates, rather than a single big one. Similar to how the Indian continental plate pushes north into the Asiatic plate, creating the Himalayan mountains and the Tibetan plateau.


A history of many asteroids

During its formation and in its younger eras the planet was bombarded by many large asteroids, leading to many cracks in the crust and lots of tectonic plates due to the beaten up crust.


Gravitational assistance

Your planet orbits a gas giant. The gravitational forces from the gas giant influences the planet to have more intense mantle flows and volcanic activity, leading to more mountains by virtue of a greater amount of tectonic plates moving and colliding, but also more mountains due to a higher amount of volcanic activity leading to more volcanoes that lead to more tall volcanic islands and mountainous volcanically active regions such as yellowstone.


You want large amounts of internal heat to drive volcanism and crustal movement, coupled with low gravity so that mountains don't get squished back down again.

There's a random-chance way to handle that, and a much-more-likely way to handle that. The random-chance option is that you have a small world (not larger than Earth, Mars size would be good--note that Mars actually does have enormous mountains!) that just happens to have formed with an abnormally large quantity of radioactive materials in the core, so that it remains hot much, much longer than a world of that size "ought" to.

The more realistic option is to make your world a Mars-to-Earth sized moon of a gas giant in a very close orbit with orbital resonances with several other large moons that maintain orbital eccentricity, such that there is continuous tidal heating. That's the situation with Io, which is in fact quite mountainous due to being the most volcanically active body in the solar system. If it were larger (between Mars and Earth in size), with a thicker crust to support plate tectonics, it could be significantly more so.

  • $\begingroup$ I can try that, have it formerly be the moon to a gas giant and somehow have been knocked out of orbit and came to orbit the star. Also the thing with radioactive materials would help me further develop another planet that does have very high amounts of radioactive material. Thanks. $\endgroup$
    – Zoey
    Feb 27 at 2:08
  • $\begingroup$ That is a world of continuous earthquakes, also that ratio of radioactives in the core is going to mean a truly unhealthy level of ionising radiation on the surface as well. $\endgroup$
    – Ash
    Feb 28 at 10:37
  • $\begingroup$ @Ash If you want mountain building, quakes come with the territory. And what counts as "unhealthy" radiation depends on the species doing the counting--and note that rock and water are very good rad shields, so dangerous environments would hardly be universal. $\endgroup$ Feb 28 at 16:33
  • $\begingroup$ @LoganR.Kearsley Continuous earthquakes is a rather different thing to the occasional shaking that goes with mountain building on Earth, also the OP specifically vetoed it as a condition of the question. As for the level of radiation the question says "humanity", and the main radioactive element in the crust is going to be Radium, as it is on Earth, which means Radon gas spreading radiation everywhere. On the plus side there will be huge reserves of crustal helium if they want to use airships. $\endgroup$
    – Ash
    Mar 4 at 22:46

It's a water world.

A world of vast, deep, oceans will have mountainous terrain where it has solid ground at all. The only land that will rise above the waves will be mountain ridges and volcanic island chains. The weather on such a world will include vast storms that dump metres of rain where they run into high ground eroding the mountains and enriching the seas.

  • $\begingroup$ Well, that wouldn't fit my plans in the slightest, and actively contradicts my ideas of what it would be like. Is there any other way that would make it have more dry land? I don't want it to be that it is only inhabitable at the mountains, just for it to be more far mountainous than Earth. Preferably with little water. $\endgroup$
    – Zoey
    Feb 26 at 16:31
  • $\begingroup$ @Zoey Not if you want low earthquake activity, to have a lot of dry land and most of it be mountainous you're talking about a very geologically active world, that means a lot of upheaval and volcanism. Or a dead world hammered by impacts. $\endgroup$
    – Ash
    Feb 28 at 10:33

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