So...I have an interesting predicament.
If it's not obvious from the picture, that's an erupting volcano. I've seen magma overflow like this before, with the most notable example being a reclaimed worldgen fort where the magma forges slowly flooded, but I've never seen it at this scale. It's pouring out of the sides at a rapid pace and even splashing up onto the hill overlooking the volcano's caldera. The nearby mountains are also acting like a funnel, causing the lava to flow from the southeast corner all the way across the map of this 3 wide, 5 high embark, off the west border and into the northern valley, filling the dried murky pools with lava and setting all the trees on fire.
Here's the retracting bridge that seals the fort's original entrance, shortly before the lava blocked it off.
Here's what the lava did to the valley below. Note that some of the scattered red tiles here are actually red sand.
Needless to say this is interfering with my plans to capture and tame the local wildlife. Nothing dissuades curious elephants from investigating your cage traps quite like an encroaching wall of molten rock.
A bit of history on this fortress: Copperdrive (soon to be !!Copperdrive!!) was founded amidst the scorching hot mountains and tropical shrublands in the center of the world. With the stream to the north providing water and the volcano to the southeast supplying magma for forges, the dwarves of The Humble Town would have all they needed to carve out a living... once a certain delivery was made, that is. The fort was retired as soon as the dwarves had a working entrance, before so much as a farm had been built.
Hearing rumors of the new fort, the peregrine falcon man Udib Ironswords the Mountainous Gate of Risking, renowned evader of bogeymen and occasional adventurer when his wits failed him, was compelled to leave retirement and make his way south with a bag full of 1,000 singing metal coins, which had been minted at his overcrowded home fortress of Squashedmirrored from armor he'd salvaged from a nearby vault. Udib flew over elven ruin and restless sea, fought off goblins and giant bark scorpions and stared down the occasional timid unicorn. After three days of travel, he safely arrived at the new fortress of Copperdrive. There he dropped off the coins in the nearest stockpile, as they were to be the foundation of Copperdrive's economy (by which I mean I was going to melt them down one by one and reforge them into equipment for the budding military and maybe a weapon rack or two.) Udib then boasted of his great deeds to the local militia captain, Dakost Enjoylanced, and begged to become a soldier under her command. Dakost graciously accepted and Udib retired from the adventuring life into military service.
With the awaited delivery fulfilled, the dwarves unretired the fort and found that in the celebration following Udib's arrival, every barrel of ale and bag of sand had been overturned. Ilral Smithwilts also noticed during bookkeeping that the level of lava in the caldera was oddly high, but with the sudden concern over lack of booze none of the dwarves paid it much notice. The miner Stinthad Ragmaze began immediate construction on a tunnel to supply water to the fort, while Ilral made plans to carve a second tunnel to supply magma for the forging process once her bookkeeping was completed. By the time the former was nearing completion the latter proved redundant; the volcano had opted to deliver the lava of its own accord.
The fortress immediately went on high alert, and every dwarf and peregrine falcon man's location and activities were checked. Udib Ironswords the Mountainous Gate of Risking, experienced adventurer and slayer of dangerous beasts of all manner, had gotten himself stuck in a tree. (His flight capability still exists in fortress mode but does nothing for pathfinding.) Several of the dwarves were caught outside, wandering back and forth between the fortress and the nearby stream. But worst of all, Ilral Smithwilts had decided to take a nap by the stream, blissfully unaware of the approaching lava.
The local carpenter, Iton Booksilvers, grabbed an axe and bravely rushed out to cut Udib down. She cut through the trunk with deforesting speeds only a dwarf can achieve and the tree fell with a crash.. only for Udib to remain suspended in midair, flapping his wings indifferently. Irritated, Iton grabbed the fallen logs and started building a staircase with the intent to reach up and grab Udib, but as she was putting the finishing touches on it Udib felt a pang of thirst and flitted past, landing neatly on the ground below an exasperated Iton and proceeding to the stream for a drink.
Meanwhile, the miner Stinthad Ragmaze raced out to channel the final tile at the edge of the stream, the last step needed for the fortress's water supply. (Channeling out the last tile blocking the flow of magma or water from above is a step I take to ensure the miner's safety, ironically.) Once he completed his work Iton took over, grabbing the wood from her half-constructed staircase and using it to seal the hole. She then ordered the dwarves using the stream and Udib, especially Udib, to exclusively use the new well for their water. Unfortunately, no one could wake Ilral, so the dwarves retreated inside and prayed she would do so of her own accord before it was too late.
The dwarves huddled together inside their roughly chiseled new home as the lava advanced to seal them in. They waited as long as they could for Ilral, but the lava drew ever closer and still there was no sign of her. With a heavy heart, Rigoth Cloisteredpassions pulled the lever to seal the gate, but as he did so there was a shout from outside. “Wait!” Ilral bellowed, the heels of her shoes streaming black smoke as she raced over the lava flows towards the entrance. Rigoth opened the bridge once more and Ilral dashed in, racing to the bridge lever and yanking it as hard as she could. The gate closed with a crash, and moments later the hiss of lava was heard atop it, sealing the dwarves off from the outside world.