This article establishes approximate empirical relations for determining the minimum unit stream power, bed shear stress and mean flow velocity capable of moving cobbles and boulders on streambeds. The derived equations then are used to estimate the minimum paleoflows that could have transported the boulders of two ancient fluvial deposits in Sweden. The flow estimates are compared with those made by more conventional hydraulic methods. Bankfull flows also are estimated for one of the two deposits, using various hydraulic equations.