 Its upper course is called Whitestone Beck.The river's main tributaries are Muddypool and Ayside Beck, which converge above Cartmel.The river rises near High Cark in Newton Fell and the Whitestone Enclosure, and is soon fed by "Black Beck" (emanating from Fair Rigg south of Staveley-in-Cartmel) and "Ayside Pool" (rising above Ayside).