The moorland area between the valleys, High Cup and Great Rundale is fairly flat with a number of tarns, large and small; the one in the image is un-named on OS maps despite its reasonable size. Backstone Edge lies behind the camera position and is simply the vague line of the break of steepness on the slope - there's no actual rock edge as would be understood from use of the word elsewhere, in The Peak District for example.
Uploaded to Geograph by Trevor Littlewood on 11 June 2015
Photo © Trevor Littlewood, 11 June 2015. Licensed for reuse under this Creative Commons licence