The river Don has a remarkable semicircular course. Rising in the Middle Grits, west of Dunford Bridge, at 1,500 feet above O.D., it flows eastwards to Penistone (700′), where it makes a bend to the south-east, quickly deepens its valley to 500′, and at Wortley breaks through the great watershed (1000′) of the Grenoside and Wharncliffe grits. It then receives the Little Don, the Ewden, and the Loxley, on its right bank, and falls into the valley of the Sheaf at Sheffield (150'). The Don then makes a rectangular bend to the north-east, following the old valley of the Sheaf to Conisborough, receiving the Rother on its right bank at Rotherham (87′) and the Dearne on its left bank at Denaby (45′). It then traverses the Magnesian Limestone escarpment in a fine gorge, and continues past Donoaster in a north-easterly direction to Thorne, where it bends northward towards the Aire. It has, however, been artificially diverted by the Dutch River to the Ouse at Goole.