Argh, having a bit of aquifer difficulty. Despite the embark screen not listing any, I found a whole bunch of tiny random ones all over the grassy half of my map - where I've been trying to level the land and dig out a new river and moat. You'd think this would be helpful, but the aquifer levels are higher than where I want to level the land down to. And since I'm concerned about making thhe area look nice, I'm not content to simply wall off the offending areas or go around. So I've been digging them out in the winters, then leaving just an ice wall around the direct aquifer tiles... then in the spring, sending in engravers to rush against the water and smooth them off, later draining them out with pumps. It's taken... well, it's winter of the eighth year currently, so almost nine, doing about one level a year and starting a few years in. Fortunately I think I'm on the last level now before I'm happy, but dear christ that took a while.
I'm thinking that to get the natural grassy look back to these new stony layers, I'll flood them to make them muddy and then build and destroy farm plots to get furrowed loam. Dunno if furrowed loam tiles will start to grow grass, trees, and shrubs again if outside, but no harm in trying. I'll prefer furrowed loam to rock on the visualizars, anyhow.