Sediment mobility and the resulting erosion of bedrock are the primary controls on surface denudation and landscape evolution in humid subtropical environments. This study investigates the movement of coarse sediment grains in Cheaha Creek, a step-pool headwater stream located in the tectonically passive Talladega Mountains of northeastern Alabama. The frequency and magnitude of stream discharges large enough to mobilize sediment grains ranging from fine sands to large boulders are analyzed in this research. Results indicate that depending on the size and orientation of surrounding sediment grains, coarse gravel to large cobbles are potentially mobile at 1.5 year recurrence interval flows, and the 4.5 to 8.5 year flows have the potential to mobilize small to large boulders. These findings suggest that coarse sediment grains are mobile on relatively short timescales and the opportunity for bedrock erosion and resulting landscape denudation in the Talladega Mountains occurs frequently in the current climatic regime.