3 ms·

Layman curiosity about mountains (for fictional worldbuilding): Are they completely solid inside? Or can they be "porous" with natural caves or holes internal

• ip26 7y ago
  They can have caves and such. Granite and I believe also sandstone tends to be totally solid, but limestone tends to form extensive cave networks from water seeping through the rock. Basalt can also have caves from anciet magma chambers but I don't think those usually lend themselves to human exploration.