Questions about caves, cave ins, and palisades.

[Entropoly]

-Are cave ins indestructible or just of a random hardness?
-Are caves and the world map above 1-1 ratio with each other, or does going underground 'shrink' the distance it takes to walk from one place to another?
-Can a cave in destroy a palisade, and does that cause a chain reaction break if so?
-Can a cave in destroy a nearby mining support, and if that mining support is destroyed by a cave in does it cause another cave in?
-Can a cave in destroy a mine hole?
-Can a mining support block a mine hole from being built in that area? (would be a cool feature, but I assume no)
-If you cave in an area around a cave entrance's 'unbreakable block' zone, do those new blocks become unbreakable?
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[min_the_fair]

Cavein boulders are destroyable - you can't mine them or chip them, only destroy.
The world has a 1:1 ratio

...

Someone did cause a cavein in the unbreakable area and the blocks did become impossible to mine, blocking the cave. I cba to look for the thread again but I think the general idea was, that this might be fixed by Loftar at some point. So I don't recommend doing this in an attempt to deliberately block a cave.

[Entropoly]

Just tested a mine support cave-in in a cave next to a palisaded cave entrance. No cave-in happened at all, so either something stopped it (which it says a cave-in always happens) or you just can't cave-in in the cave entrance area?