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0001176Dwarf FortressCave-inspublic2010-04-14 19:012011-03-30 10:26
Treason 
 
normalminorhave not tried
newopen 
0.31.03 
 
0001176: Ice Cave-ins for water in Glaciers producing odd results.
So I was following the old method of creating water for my dwarfs in a glacier (dug down 40 levels, couldn't hit any sort of cavern) by digging out and causing a cave in below the lowest Ice level.

My pattern was such:

Top z-level: ---------------
              -+++++++++++++-
              -+-----------+-
              -+-----------+-
              -+-----------+-
              -+++++++++++++-
              ---------------
- = cleared ground
+ = Channels

The two z-levels of ice below this were created in the same pattern. I dug out two z-levels below this to capture as much water as possible. Upon dropping the whole thing, I now have the lowest (2 levels below the freezing line) filled with ice, the level above with water, then a level of ice and water along the outer rim of ice, which has become an ice wall..above that I have a free hanging ring of ice walls with the very center now empty space..and at the very top level I had dug out, there are now amazingly floating chunks of ice.

The only thing I can think of (if this is really working as intended) is that the resulting water splashed up and reformed into ice in the process, though I am confused as to how the lowest level of the dug out cistern is ice..but the level above it is melted water..and the level above that (now at the z-level where you have dug through the ice and hit rock) is ice with an ice wall rim.

Either way, it has produced massive amounts of FPS and computing slow down, when not paused.
Embark on a glacier with 4 z-levels of ice.
Dig down from the surface and mine out an area you intend to drop.
Dig out the outer edges of it (leaving the center intact, of course) all the way down until you hit rock as the floor.
Dig out two levels below that, using channels.
Go back up and cut free the ice block. Watch resulting cave in.
No tags attached.
related to 0001932confirmed Footkerchief Ice over water cave-in produces blocks of rock and "Unknown" 
Issue History
2010-04-14 19:01TreasonNew Issue
2010-04-14 20:39FootkerchiefNote Added: 0003609
2010-04-14 20:39FootkerchiefIssue Monitored: Footkerchief
2010-05-06 14:56FootkerchiefNote Added: 0006313
2010-05-06 14:56FootkerchiefNote Edited: 0006313bug_revision_view_page.php?bugnote_id=0006313#r2362
2011-03-30 10:26FootkerchiefRelationship addedrelated to 0001932

Notes
(0003609)
Footkerchief   
2010-04-14 20:39   
Do you happen to have a save from before the cave-in? It would be helpful for reproducing this. Also, your diagram unfortunately didn't work out -- try uploading a screenshot instead: http://tinypic.com/ [^]
(0006313)
Footkerchief   
2010-05-06 14:56   
Any chance of getting the save I described?