 The source of the river is on the slopes of Great Hill, just above the ruins known as "Pimm's", where the infant river is known as Calf Hey Brook.Calf Hey Brook is joined by another stream occasionally termed Roddlesworth - which rises beneath Cartridge Hill and runs past the ruins of "Hollinshead Hall" - beneath "Slipper Lowe".From there, it follows a northerly course through Roddlesworth Plantations, around the two reservoirs fed by the river and past Red Lees.