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Author Topic: Can a cavern be cleared out?  (Read 1728 times)

OmahaMH

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Can a cavern be cleared out?
« on: November 12, 2018, 02:29:41 pm »

I always discover caverns and dig around them because the nasties inside would devour my hapless, military-less (I haven't quite traipsed into that part of the game yet) dwarves without much effort.  I know this because it has happened in previous fun games.

If I do build a military and train them and send them down there, is it possible to clear the cavern out such that it will be safe for worker dwarves to come down and grab plants, and minerals, and build things there, or will new baddies constantly come in from the open edges of the map or spontaneously appear?
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Bumber

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Re: Can a cavern be cleared out?
« Reply #1 on: November 12, 2018, 04:24:46 pm »

A new wave will show up as soon as the old one is killed off.

Using cage traps and throwing them in a pit should prevent new waves for the rest of the season.
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Astrid

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Re: Can a cavern be cleared out?
« Reply #2 on: November 12, 2018, 05:23:40 pm »

If you keep ready stoneblock pile near the target of desire and watch the local fauna (there are benign ones) and take a look at the local topogaphy of that cavern you might sometimes be able
to wall of huge parts of the cavern for your own use simple by placing 3-5 short walls at strategic locations. Be warned tho. Missing gaps is easy.
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PatrikLundell

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Re: Can a cavern be cleared out?
« Reply #3 on: November 12, 2018, 05:57:58 pm »

It IS possible to wall off cavern, though. When done (correctly), a cavern is completely safe (well, as safe as any part of a fortress).

The way I do it:
- When the cavern is breached (by digging up/down stairs), plug the breach immediately by building an Up (only) stair two levels above the breach (for some reason it can't be built at the breaching level). Dorfs can build this Up stair standing on the building tile.
- Prepare for cavern entry by building an airlock with a bait door and a number of cage traps in it. An "airlock" is a space between two raising drawbridges, each controlled by a lever. The outer one (closer to the cavern) should be one tile away from the cavern so a miner has to remove a single tile to open up the passage. The door can be locked to delay critters trying to enter sufficiently long for the drawbridge levers to be pulled (and it's a good idea to test that the drawbridges and levers are constructed correctly before opening up the cavern access...).
- Wait until the critters visible are of a reasonable benign type (such as elk birds or rutherers). Station your militia (which in my case typically is the dorf who was assigned the spare embark axe, with no training or other equipment) by your airlock and designate the access tile to be mined away (I give it priority 1 to get it done reasonably promptly). Once the access is free (or before that, actually), make a burrow that covers the whole embark except the cavern you're breaching and set it as a civilian alert burrow which you activate. This stops every dorf and his uncle from rushing into the cavern to haul those EXTREMELY VALUABLE old bones to the refuse and corpse stockpiles. Move your militia around the cavern by setting up new stations as more of the cavern is revealed. This way you should be able to explore it. Withdraw if you see nasties, or when the cavern has been explored. Station your militia inside of the airlock and close the outer drawbridge.
- Wait (it may take years if the timing is bad) until you get a new batch of benign critters entering the cavern. As you've explored it, you'll see everything in it (except Gremlins, but they're rare and not particularly dangerous). The latest critter to enter the embark is listed at the top of the Units/Other screen, so by checking that screen you can see when a fresh group has entered.
- Once you finally have a benign group in the cavern, open up the cavern (no civ alert [and you did remove the old one when done, right]), send your wood cutter(s) to cut trees in the cavern, with priority to clear the edges (so you can build there). Select a number of sections along the edge for an "exterior" (I use 4 of those, one on each side) where you build a wall one tile in from the edge so a single tile space exists between the wall and the outside. Any critters entering there will be stuck there and stay around until they leave (except FBs, which stay until killed by other FBs). These walls are built from the wood of the trees cut, and I typically select as long a stretch as possible that's as low as possible. If the stretch is higher than a single Z level, build a ramp to allow you to get up on top of the wall to build a wall above the gap created (i.e. flush with the edge), and if it's more than two Z levels, build Up stairs on top of the lower wall to reach higher (I try to space those 3 tiles apart). Build Up/Down stairs on top of the Up stairs and continue until you reach the roof, and build your wall, level by level (I assume you know how to build high walls).
I don't actually do exactly this, but build "outer" drawbridges in preparation for airlocks to those sections (don't forget to place an Up stair above the bridge to plug the hole if more than two Z levels, and a floor if 2).
- You'll typically can't build a complete section before the critter group leaves, so once it's due to leave (I use the groups for the other caverns and the surface as estimates of when it's due), activate the cavern civ alert to withdraw your builders and wood cutters, raise the outer airlock drawbridge, and wait for a new building opportunity.
- Once your first section is done, there's a chance an entering group enters on the outside of the section, and if so, it's reasonably safe to file out into the cavern to continue working ("reasonably safe", because FBs can arrive at any time, and savage biomes allows for two concurrent groups). Once all sections are done, there's a good chance entering critters end up in one of those, allowing you to work on the next phase, which is to cover up the rest of the edge. Build walls flush with the edge (on every Z level), until the whole edge is covered by walls or exterior spaces (typically over multiple sessions). Once done, everything is "inside".
- If there are cavern lakes that extend to the edge. magma has to be used to obsidianize them, which is a pain, but possible. Trees in cavern lakes can be removed by firing ballista bolts at them.
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Grand Sage

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Re: Can a cavern be cleared out?
« Reply #4 on: November 15, 2018, 12:12:00 pm »

couldn't you also hunt down the "nasties" until they go extinct? much like normal wildlife?
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PatrikLundell

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Re: Can a cavern be cleared out?
« Reply #5 on: November 15, 2018, 12:44:44 pm »

couldn't you also hunt down the "nasties" until they go extinct? much like normal wildlife?
In theory, yes (and definitely with hacking). However, reanimating biomes that "convert" caverns into teeming messes of reanimated critters that rapidly recruit newcomers do not seem to stop new recruits from arriving.
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Bumber

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Re: Can a cavern be cleared out?
« Reply #6 on: November 16, 2018, 12:39:42 am »

couldn't you also hunt down the "nasties" until they go extinct? much like normal wildlife?
Probably not in a reasonable time frame. Walling off the edges of the map would be quicker.
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Reading his name would trigger it. Thinking of him would trigger it. No other circumstances would trigger it- it was strictly related to the concept of Bill Clinton entering the conscious mind.

THE xTROLL FUR SOCKx RUSE WAS A........... DISTACTION        the carp HAVE the wagon

A wizard has turned you into a wagon. This was inevitable (Y/y)?

Ertosi

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Re: Can a cavern be cleared out?
« Reply #7 on: December 31, 2018, 02:55:54 am »

Walling everything off is my preferred choice as well. Patrik well covered most of the suggestions I was going to make on how to do it safely. I highly suggest setting up airlocks as he mentioned.

Cage traps are very useful for keeping your dorfs safe; before my caverns were fully tamed I scattered them everywhere and would lead trouble towards them.

Once everything is walled off and safe, consider adding a few other features.
  • I had an underground river in mine so had to set up a way to block off water access. Even without that, consider setting up a good drainage system in case you run into flooding issues down the road. Cage traps still worked great vs pond grabbers and cave crocs.
  • Consider adding a good sized air lock (with drawbridges) along one of your main cavern walls. Line it with cage traps as well as a bridge smasher, in case of getting something truly nasty. Then leave the outer bridge open. This will let you catch valuable cavern livestock which you could slaughter or keep for breeding programs.
  • Fully tamed caverns are fantastic as pasture land for cave grazers. Set up a few different large pens and move livestock around to prevent any overgrazing.
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