I had a good idea. But then it turned bad.
I captured some goblins with cage traps and thought I'd either do a cave in on them, or drop them into the cavern which hosts some four-horned humanoid made of solid salt and see what happens. Well, after a series of errors and miscalculations, I now have 4 goblins floating in space, and 3 goblins in traps sitting on top of a wall. How this came to be I really don't understand, but now my dwarves refuse to go near there to fix the problem.
On the lower level I have something like this:
sooooooo
fowffffo
fowffffo
fowffffo
sooooooo
Forgive me for using the wrong symbols. s = unmined stone, o = open space, w = constructed wall, f = floor. The goblins are running around on that floor. It is completely disconnected -except- for those walls. All of these tiles are open one level down, there are no lower level supports or walls etc.
Up one level it looks like this:
sssffsss
focooooo
focooooo
ffcooooo
sssffsss
c = goblin in a cage sitting on top of a constructed wall. The floor areas there are areas I cut out to try and get to that last floor tile. But the dwarves keep getting scared by the loose goblins below and running away. I think if I could channel it out, the top floor might cave in and knock the lower floor out. But as it stands my dwarves won't go near it. How it actually got to this point, considering this fact, is actually something of a mystery to me right now.
The level directly above this level is a cavern in which roams yet another forgotten beast, an earthworm with a hardened shell and mauve feathers or some such, as well as a couple armies of crundles. Not exactly safe territory for miners.
So, what can I do? I can try to get better screenshots to show it better but the basic thing is that the walls on which the goblins in cages are built seem to be anchoring the lower floor from falling away. My army is not capable of handling them, even if they could reach them. Will the goblins eventually die of thirst/hunger? It doesn't seem likely as it's been a while and they're showing no signs of tiring.