We could see a lake in the cavern, so we dug out an area next to it and attempted to flood it, causing the floor to muddy. Nothing grew there, just like the rest of the cavern. We converted the area into the main hall, filling it with workshops and stockpiles.
We had to slaughter the trusty buffalo which had got us here for food. And they were starving.
Onwards we pushed, until damp walls we discovered. We mined through above into another cuge cavern, this one with large trees and moss. No shrubs, but moss and fungus were what we needed.
We walled off an area and let the animals graze happily.
I oversaw the beginning of some facilities in the main hall, a bed each, a statue area, and more workshops and stockpiles. It was a mess but it was home, and would be until we had enough time and resources to dig proper rooms.
We began a farm, sheared and milked the animals, made some nest boxes for the birds, and secured the cavern areas with doors. We had food a plenty, the walls were teeming with minerals (highest minerals guys, but no flux.

) and we seemed safe.
What could possibly go wrong?
EDIT: Well we're fkd.
1 cavern has moss, trees and shrubs, one trees, one nothing.
The chicken and goose have unclaimed their nestboxes and refuse to reclaim them.
There's jobs and items lying around that nobody's doing/touching.
We got a hunter, dyer and wax worker as immigrants... ¬¬
Generally buggy and ugh.
Oh well!