<p>A planet has been theorized that forms in a primordial disk of high carbon content. See <a href="https://en.wikipedia.org/wiki/Carbon_planet" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Carbon_planet</a>. This planet's crust would have a high hydrocarbon content and thus not be very "solid". However, such a planet might theoretically have volcanoes that erupt diamonds, so an alien could build there home out of diamond!</p>

<p>Another hypothetical planet is a waterworld or ocean planet. If there is indigenous life then the only "above water surface" would be composed of life (ie: mats of algae type material floating on the sea).</p>

<p>As far as mountains go, this is not a question of solid or not solid. A large superearth would likely not have much in the way of mountains because of the high gravity at the surface. It might be noted that with out plate tectonics, we wouldn't have mountains and the Earth could arguably be covered in a global ocean.</p>

CC BY-SA 3.0
2017-08-07T06:02:01.353Z
Mars & Venus don't seem to have plate tectonics, but do have mountains.
jamesqf
CC BY-SA 3.0
2017-08-15T14:38:12.243Z
Venus may have had plate tectonics at one time, but I agree that mountains can be of volcanic origin or impact. My argument is that sustained volcanic activity (once a planet has cooled significantly) would probably require plate tectonics. (I may be wrong here.) Then, I would argue that gravity and erosion (especially on a super-earth with a thick atmosphere) would wear away the mountains over the eons. Of course, a planet like Mars would have little erosion and weak gravity.
Jack R. Woods
CC BY-SA 3.0
2017-08-07T01:31:05.620Z
2017-08-07T01:31:05.620Z
Jack R. Woods
<p>Are there planets that lack mountains or have constrained availablilty of solids. For example a planet that has clay but not more solid stones like normal stones. The direct reason why I wonder is because I started to wonder if there existed planets where one would have to build less solid houses then at the earth due to the solids available if a person would build a house on that planet hypothetically spoken. It would be really nice with a detailed answer of what solids another planet would lack and how it constraints the housings that could be built on that planet in terms of solidness.</p>

CC BY-SA 3.0
2017-07-29T20:05:41.407Z
Perhaps better suited to the Astronomy site?  But trivially yes: the gas giants either have no solid surface, or it's so far down we can't see it.  Then some of the Galilean moons of Jupiter, like Europa, have surfaces of ice that are fairly smooth.  And if you go to Pluto, you can build with nitrogen ice :-)
jamesqf
CC BY-SA 3.0
2017-07-30T03:27:18.827Z
As for clays: (at least on earth) they form when solid rocks are exposed to surface conditions: low temperature and humidity.
Gimelist
<planetary-formation>
Mountains and solids on other planets
user1008293
# Mountains and solids on other planets

(Asked by: username_0 on 2017-07-29)

Are there planets that lack mountains or have constrained availablilty of solids. For example a planet that has clay but not more solid stones like normal stones. The direct reason why I wonder is because I started to wonder if there existed planets where one would have to build less solid houses then at the earth due to the solids available if a person would build a house on that planet hypothetically spoken. It would be really nice with a detailed answer of what solids another planet would lack and how it constraints the housings that could be built on that planet in terms of solidness.

**Tags:** planetary-formation

> **Comments:**
> **username_1**: Perhaps better suited to the Astronomy site?  But trivially yes: the gas giants either have no solid surface, or it's so far down we can't see it.  Then some of the Galilean moons of Jupiter, like Europa, have surfaces of ice that are fairly smooth.  And if you go to Pluto, you can build with nitrogen ice :-)  
> **username_2**: As for clays: (at least on earth) they form when solid rocks are exposed to surface conditions: low temperature and humidity.  

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## 1 answers

### Answer by username_3 on 2017-08-07. Score: 0 | Accepted answer

A planet has been theorized that forms in a primordial disk of high carbon content. See <https://en.wikipedia.org/wiki/Carbon_planet>. This planet's crust would have a high hydrocarbon content and thus not be very "solid". However, such a planet might theoretically have volcanoes that erupt diamonds, so an alien could build there home out of diamond!

Another hypothetical planet is a waterworld or ocean planet. If there is indigenous life then the only "above water surface" would be composed of life (ie: mats of algae type material floating on the sea).

As far as mountains go, this is not a question of solid or not solid. A large superearth would likely not have much in the way of mountains because of the high gravity at the surface. It might be noted that with out plate tectonics, we wouldn't have mountains and the Earth could arguably be covered in a global ocean.

> **Comments:**
> **username_1**: Mars & Venus don't seem to have plate tectonics, but do have mountains.  
> **username_3**: Venus may have had plate tectonics at one time, but I agree that mountains can be of volcanic origin or impact. My argument is that sustained volcanic activity (once a planet has cooled significantly) would probably require plate tectonics. (I may be wrong here.) Then, I would argue that gravity and erosion (especially on a super-earth with a thick atmosphere) would wear away the mountains over the eons. Of course, a planet like Mars would have little erosion and weak gravity.  

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