 Oldham 's topography is characterised by its rugged , elevated <unk> terrain . It has an area of 6 @.@ 91 square miles ( 17 @.@ 90 km2 ) . The geology of Oldham is represented by the <unk> <unk> and Coal Measures series of rocks . The River <unk> , flowing northwards , forms the boundary between Oldham on one side and Royton and Shaw and Crompton on the other . 
