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0010746Dwarf FortressDwarf Mode -- Environmentpublic2018-05-03 10:332019-03-09 08:08
normalminorhave not tried
x86_64Microsoft Windows 10 Pro10.0.16299
0010746: Attempting to remove river tiles during winter via ramps can result in "empty" tiles which cannot be built on or moved through.
In order to remove "River" tiles and convert a semi-dried riverbed to farmland, I have been digging ramps during winter, removing the ice ramp (which restores the original River tile, but dry), and building constructed floors on the River tiles. Removing the construction then gives a normal soil tile.

However, while building my latest expansion, some of the removed ramps instead give a completely black tile (neither a River tile, an Ice floor, nor a soil floor). This tile is impassible to dwarves and cannot be built on, but appears "empty" when viewed from the Z-level above (in the
In this save: http://dffd.bay12games.com/file.php?id=13724, [^] there is a row of the tiles in the riverbed near the middle of the map, just south of the F1 zoom location. (From the F1 zoom, the tiles can be seen by their blue "two Z-levels above water" colouration.)

Removing the ramps to the right of these tiles has not replicated the bug, which suggests it may be related to an earlier investigation, but I will reupload a further save if I discover other tiles which can replicate the effect.
No tags attached.
duplicate of 0008400acknowledged Loci Removing natural upwards ramps from icy brook floor produced empty tiles 
Issue History
2018-05-03 10:33fishsiclesNew Issue
2018-05-03 10:40fishsiclesNote Added: 0038249
2018-05-04 22:48George_ChickensNote Added: 0038252
2019-03-09 08:08LociRelationship addedduplicate of 0008400
2019-03-09 08:08LociStatusnew => resolved
2019-03-09 08:08LociResolutionopen => duplicate
2019-03-09 08:08LociAssigned To => Loci

2018-05-03 10:40   
Updated the save with a slightly different version which can replicate the bug properly. I believe the bugged tiles result from ramps which formed through this process:

1.) During a previous winter, build a constructed floor over an ice tile.
2.) Remove this floor. This results in a permanent ice tile rather than the soil tile, I don't know if this is intended.
3.) Let water return to this tile and flow over it, freezing into an ice wall the next winter.
4.) Dig a ramp into the ice wall.
5.) Remove the ramp.

This produces the "empty" tile. The ramps which are eligible to reproduce the bug immediately in the save are on the left side of the excavated riverbed.
2018-05-04 22:48   
I can confirm, I had this problem while trying to dam a river.