Sometimes stations along the main shaft have cellars..
L A Y E R S
Ice Mineshaft in a Better Caves cavern
A rare Mushroom Mineshaft!
An Acacia Mineshaft in a savanna biome
A normal oak mineshaft
An old miner's outpost. Maybe he's still in there?
Oak Mineshaft in a Better Caves cavern
Snowy Mineshaft with Quark, BOP, Terraforged, Better Caves, and more