This polygon represents the lower half of Rivelin Valley. It is charaterised by woodland plantation in a steep valley. The woodland has increased in density over the course of the 20th century. Prior to this the area contained five water powered sites, the remains of which contribute to the significant legibility of the former character. Buildings survive at Mousehole Forge, elsewhere are visible remains of mill dams, weirs, goits and other structures. Several of the mills date from the early 17th century with the rest dating to the early 19th century. This area within this polygon forms a significant location for understanding water power and early post-medieval industry in Sheffield.