I was on a cycle ride, near Whittle Dene reservoirs, when I spied some concrete structures a hundred yards off the road. So I stopped and pushed the bike across a field to take a closer look. A typical bike ride for me involves riding slowly and stopping to take a look at things – particularly when going uphill.
The blocks (there are two of them but only one shown here) appear to act as weights to open and close a sluice system.
Olympus 35RC, Ilford HP5+ rated at EI400, and a yellow filter. Developed in HC110, Dilution E.

Something for future generations of archeologists to ponder no doubt! Nice image 🙂