We only went so far, as we did not wish to get our delicate lurcher-feet wet.
I'm slightly confused by this one, if I'm honest.
According to the Heritage Gateway, just ahead of Rosie is a 20th century shaft, which was ' wired by levels from no.2 Adit (to the NW)'. But I don't see how it can be connected to an adit that is to the NW, because the hill falls away so steeply: there is nothing to the North West except empty space: the closest mine is in the middle of the hill, Southward. (There is Holmbush Mine to the NW, but that is quite a long way away and a lot lower down.)
The way the valley is full of water makes it look much more like an adit (draining water out of the hill) rather than a shaft going down. Also, if this connects to a mine to the South, it seems odd if it's a 20th century shaft, because Kit Hill summit mine closed in 1864. Probably you need to be more intrepid than me to solve this one.
Here's a mystery wall instead. This is 'A rectangular shelter, built of split granite blocks open on the north side where it faces onto a stone working area. It is associated with the lower quarry on the north slope of Kit Hill.' It's now sheltering a collection of small, worried-looking trees and a lot of disturbingly altar-looking rectangular blocks of granite.
This is what's to the North West of that valley. Nice view of Bodmin Moor anyway.