the south fork is an tributary of the little cacapon. the south fork is formed at its headwater in a hollow towards the southeastern end of stony mountain along south fork of little cacapon road (county route 12) between the communities of kirby and ruckman. from its source, the south fork flows northeast toward bell hollow, where it meets us route 50 and turns north through frye's flat towards frenchburg. the south fork continues north under us route 50, where it immediately joins with the north fork to form the little cacapon river alongside little cacapon river road (county route 50/9).