Underneath the garden

On quite a lot of old maps, including the one I placed on the blog, you can see a Mill Race on the map, running parallel to the river, on 'my' side. A mill race is basically a divertion of a natural waterway for hydropower purposes; the idea is that you build a weir, divert the water into a narrow channel so it speeds up, and which then powers a waterwheel. Behind the waterwheel you let your mill race drain back into the waterway it came from. There was no sign anymore of the weir in the river, at least not that I had seen; I had assumed the mill race was gone too. Until I went swimming in the river. And saw a tunnel go underneath my garden. I went back to get boots, trousers, gloves and my helmet to have a look. It was the mill race! It was easily high enough to stand for about five meters. After that, it gets too low to even crawl underneath, at least for a few tens of centimeters. It goes in two directions, even! I didn't see that on any map. It looks like both branches get a bit higher after the initial tight bit!

I had no idea my garden is hollow! I think there may be more lurking underneath. Somewhere landward of the mill race as indicated on the map, small holes appear in my lawn, that look like the topsoil is falling through gaps between the slate it is lying on. Maybe that's the branch going off to the left! Luckily the mill race looks structurally sound. It's quite exciting to have my garden straight on top of such industrial heritage!

 

A black hole! What's this? 

 

Above it is my garden

 

What it looks like on the inside

 

Looking out 

 

The mill race (or rather, by the looks of it, only the above-ground part of it) on the map. My house (and that of the neighbour - they're connected) is the J-shaped one to the left of the slate yard