The world I designed, while habitable and capable of hosting carbon based life is characterized by a considerable volcanic and seismic activity caused by the tidal heating of the gas giant it orbits.

Among the features that I would like the world to have there would be a system of natural caves spanning some areas of the planet, possibly big enough to contain their own secluded ecosystem similar to the Hang Son Doong caves in Vietnam but much bigger, numerous and extensive, with my aim being that they'd be capable of hosting even small settlements or even entire secluded civilizations inside them.

Would a world with the conditions that I described allow for such cave systems to exist? And if yes, would it facilitate or impede their formation?

For some additional information:

  • World mass: 0.7 earths
  • World Desnity: 1 Earth
  • Primary planet mass: 3 jupiters
  • Semi axis major: 2 moon-earth distances
  • Eccentricity: between 0.01 and 0.001
  • Land to sea ration: 60% water 40% land
  • Four major continents, a handful of minor ones and numerous islands
  • The climate would be generally tropical, meaning that erosion would be considerable

2 Answers 2


Your cave systems are burrows.

Burrow architecture, family composition and habitat characteristics of the largest social African mole-rat: the giant mole-rat constructs really giant burrow systems


Stuff turns over fast on your active planet. It takes much geologic time for caverns to naturally form. You dont have that long. Your cavern systems form fast because they are not natural.

There are big things that make these caves. These wormlike denizens of the deep earth are mineral eaters, and representatives of a much deeper ecosystem that overlaps a little bit with your surface world. Like sperm whales diving deep to feed in the dark undersea, your burrow makers sometimes visit the shallows, leaving caves and tunnels in their wake.

These rich fresh caves are quickly colonized from adjacent older tunnels. Vegetation including mineralovorous vegetation stabilize the walls. Herbivores and then carnivores move in.

Burrow caves also collapse on a regular basis as one would expect given the dynamic nature of your world. The caves on your world are not static ageless areas like the caves on our world. They are more like old growth forests - built by life, and prone to turnover and renewal from weather, fire and life.

  • $\begingroup$ Hmmm, very clever, having the caves build up over time thanks to critters capable of breaking through the rock and forming the structures instead of traditional methods. I like it. $\endgroup$ Jul 9, 2022 at 17:39

What you're talking about are solutional caves. This involves limestone. Limestone is the leftover shells of millions of years worth of ocean-going critters, crushed into solid rock formations. Tectonic activity then lifts that rock above the water table.

Limestone happens to be water soluble. The only reason it turned to stone was because it was saturated at the bottom of the ocean. Lifted above the ocean, rain water runs through tiny cracks, dissolving the surrounding rock, making caverns. More water can leak through the ceiling, and that's what makes stalagmites and stalactites.

So the two things you want for massive caves to be common are (a) a longer period when shelled life dominated the planet, creating larger veins of limestone (b) More geological activity, lofting the limestone above the water table

It sounds like you have the second one, so this shouldn't be hard to develop.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .