I've been working on a sky fort (http://www.bay12forums.com/smf/index.php?topic=133968.0) lately, and as a byproduct of my skyfort research, I've discovered a new and extremely counter-intuitive technique for quickly creating a large shaft down to the SMR/magma sea.
Oddly enough, the fastest way to dig deep is to build a tower up to the ceiling, then build a ring of supports at sky level. No, seriously. Here, look at these pictures:
(http://i.imgur.com/iU2HjiR.png)
(http://i.imgur.com/dmgT0ti.png)
(http://i.imgur.com/lqkNaE1.png)
(http://i.imgur.com/Ujo6UNT.png)
The first two screenshots were taken just before closing the top of the two rings of supports. The next to were taken right after. Closing the ring evidently cuts off all support to the stuff inside the ring, unless that stuff is sitting on semi-molten rock, as in the lower ring (SMR appears to be the primary source of support).
Why I think this works:
There are two types of support in fortress mode, which I will call standard support and sky support.
- Semi-molten rock is the source of standard support. Based on dfhack testing, the SMR itself appears not to need support at all.
- A tile has standard support if it is either attached to semi-molten rock or attached to a tile with standard support.
- A tile has sky support if it is either attached to the sky or attached to the bottom of a tile with sky support.
- Now, here's the key: sky support overrides standard support. If a tile gains sky support, it no longer gives support to the tiles on any of its sides.
So, by building a ring-shaped tower up to sky level and attaching it to the sky with supports, you transmit sky support all the way down to the semi-molten rock, and everything inside that ring, no matter how deep, is now unsupported from the sides. It will cave in it there is no source of support inside the ring. If the ring is over the magma sea, all that rock will drop in and disappear. If it is not, you should be able to engineer the same effect by exposing the semi-molten rock inside that ring and removing the last bit of support.
Applications
- This has to be the easiest way to make a magma death pit, on most maps.
- You ought to be able to use the cave-in effect to totally flatten the caverns.
- Have you ever thought about collapsing your whole fort into the magma sea? The correct answer is yes.
- This technique would make building a magma piston (http://dwarffortresswiki.org/index.php/DF2012:Magma_piston) much easier.
- This would be an interesting way to breach a many-layer aquifer, although it won't actually stop the water flow.
- This ought to be the fastest way by far to do the often-started, seldom-if-ever-finished "mine out everything down to the semi-molten rock" megaproject.
Collapsing Semi-Molten Rock (Update 12/16/13)
As promised, here are pictures and instructions for caving in SMR. I did it on the map's edge, too, for extra difficulty points. Casting obsidian up there is a real bitch, but some savescumming trial runs, I got it to work.
Why mess with obsidian casting? Turns out you can't build supports withing 5 tiles of the map's edge, and as you probably knew, you can't build walls or fortifications there, either. Making things even more awkward, you can't build track stops on the top level (so using minecarts to move magma is virtually impossible), and you can't really use buckets of water (since dwarves won't empty a bucket onto the level they are standing on). Basically, your only option is to pump both magma and water up to the top level, then somehow control the flow so you only cast obsidian where you want it, since casting anywhere else will probably block you from casting on the intended tiles.
(http://i.imgur.com/JpWiMwp.png)
In the above picture, you see my casting rig just after successfully casting on all necessary tiles. It's a bit of a mess. The pump stacks were located in the lower right corner of the picture. Water went through the long pipe to the left side, magma took the short pipe to the right side.
The plan was to cast the right wall first by flooding the middle area with water to about 2/7 (using a bridge to block the water from entering the magma shaft), then "disabling" that bridge (see this thread (http://www.bay12forums.com/smf/index.php?topic=134331.0)), causing the magma to spill onto the water, casting a line of obsidian just to the left of the bridge. To do the left wall, I carved fortifications in the right wall to let the magma through, then did the same thing, except this time the magma filled up the middle area.
As you might guess from the picture, there was a lot of spillover in the middle area, and it did set a lot of the map on fire. It's not necessary to do it that way.
(http://i.imgur.com/LjqnBgj.png)
In each cavern, you need to build a structure to extend the sky support downward. Stairs are easiest. The structure shown extends upward to the cavern ceiling, and I built similar structures in all three caverns.
(http://i.imgur.com/YiVUMAm.png)
I built stairs underneath all SMR tiles I wanted to cave in. After building these stairs, removing any last support should be enough to bring down the whole column, SMR included.
(http://i.imgur.com/GEpPeOm.png)
(http://i.imgur.com/Nb7MsLH.png)
(http://i.imgur.com/96FjyRJ.png)
(http://i.imgur.com/DzTpuyE.png)
In the first shot, you can clearly see that the edge of the map, normally unminable, has collapsed. That edge has been permanently lowered by 5-10 z-levels. Unfortunately, it cannot be further collapsed, because the edge is unminable and it has caved in as far as it can go. An edge created over the magma sea could be totally destroyed, because the magma flow tiles would still swallow the cave-in.
The column is not swallowed by the eerie glowing pit. Instead, it sits on the bottom of the map. Since the bottom of the map is at two different levels in my site, and the column fell on the border between the two areas, the column was split slightly.
At this point, if you did not have too many layers of SMR, you can clear out the natural stone above it to create a large skylight in Hell.
(http://i.imgur.com/jT8r5GG.png)
(http://i.imgur.com/77CxhSc.png)
(http://i.imgur.com/0KtW4Md.png)
(http://i.imgur.com/Ktm2gW8.png)
Ok, I had to use dfhack to make it snow, but that's not the point. If you have a cold map, you can literally make Hell freeze over.
New result: You can use this technique to cave in the unminable tiles on the map's edge. The catch is, you can't build supports within 5 tiles of the edge of the map, so you would have to cast obsidian to make this happen.
(http://i.imgur.com/ygwy3CI.png)
savescumming trial runs, I got it to work.
Why mess with obsidian casting? Turns out you can't build supports withing 5 tiles of the map's edge, and as you probably knew, you can't build walls or fortifications there, either. Making things even more awkward, you can't build track stops on the top level (so using minecarts to move magma is virtually impossible), and you can't really use buckets of water (since dwarves won't empty a bucket onto the level they are standing on). Basically, your only option is to pump both magma and water up to the top level, then somehow control the flow so you only cast obsidian where you want it, since casting anywhere else will probably block you from casting on the intended tiles.
(http://i.imgur.com/JpWiMwp.png)
In the above picture, you see my casting rig just after successfully casting on all necessary tiles. It's a bit of a mess. The pump stacks were located in the lower right corner of the picture. Water went through the long pipe to the left side, magma took the short pipe to the right side.
The plan was to cast the right wall first by flooding the middle area with water to about 2/7 (using a bridge to block the water from entering the magma shaft), then "disabling" that bridge (see this thread (http://www.bay12forums.com/smf/index.php?topic=134331.0)), causing the magma to spill onto the water, casting a line of obsidian just to the left of the bridge. To do the left wall, I carved fortifications in the right wall to let the magma through, then did the same thing, except this time the magma filled up the middle area.
As you might guess from the picture, there was a lot of spillover in the middle area, and it did set a lot of the map on fire. It's not necessary to do it that way.
(http://i.imgur.com/LjqnBgj.png)
In each cavern, you need to build a structure to extend the sky support downward. Stairs are easiest. The structure shown extends upward to the cavern ceiling, and I built similar structures in all three caverns.
(http://i.imgur.com/YiVUMAm.png)
I built stairs underneath all SMR tiles I wanted to cave in. After building these stairs, removing any last support should be enough to bring down the whole column, SMR included.
(http://i.imgur.com/GEpPeOm.png)
(http://i.imgur.com/Nb7MsLH.png)
(http://i.imgur.com/96FjyRJ.png)
(http://i.imgur.com/DzTpuyE.png)
In the first shot, you can clearly see that the edge of the map, normally unminable, has collapsed. That edge has been permanently lowered by 5-10 z-levels. Unfortunately, it cannot be further collapsed, because the edge is unminable and it has caved in as far as it can go. An edge created over the magma sea could be totally destroyed, because the magma flow tiles would still swallow the cave-in.
The column is not swallowed by the eerie glowing pit. Instead, it sits on the bottom of the map. Since the bottom of the map is at two different levels in my site, and the column fell on the border between the two areas, the column was split slightly.
At this point, if you did not have too many layers of SMR, you can clear out the natural stone above it to create a large skylight in Hell.
(http://i.imgur.com/jT8r5GG.png)
(http://i.imgur.com/77CxhSc.png)
(http://i.imgur.com/0KtW4Md.png)
(http://i.imgur.com/Ktm2gW8.png)
Ok, I had to use dfhack to make it snow, but that's not the point. If you have a cold map, you can literally make Hell freeze over.
I just made an interesting discovery. Did I mention that if you cave-in SMR onto the lowest revealed layer of the map, then dig downward into the unrevealed layer below, it will create sand below the SMR? Well, if not, it's related to the material duplication glitch and triggered in the same way. What's really interesting is that that sand can be smoothed and engraved.
Is this useful? Not really. But at a certain point, mere wealth is not enough to display the power and prestige of dwarven civilization. Sure, it sounds great to say the streets are paved with gold, but once the novelty wears off, gold has become just another building material, and now your streets are all cold and slippery. No, the right way to display your power is to warp reality itself wherever possible. Invading Hell just to fill in a bottomless pit with unminable material, dig beneath the bottomless pit, then engrave the history of your fort on a material that can never be engraved? That's a display of dwarven power.
Edit: I say sand because that's what I got on my map, but if the soil layers are different on your map, you may get a different kind of soil.
(http://i.imgur.com/wwWg2Co.png)