The forces that shape landscapes are characterized by variability from particle to basin scales. For example, stochastic disturbances on hillslopes and turbulent excursions in rivers mobilize particles, which then create and respond to topographic variation. Natural variations in flood discharge and sediment supply drive river kinematics, and the oscillations between accumulation and erosion control the signals preserved in stratigraphic records. Emerging work indicates that characterizing the causes and consequences of this inherent variability in geomorphic and sedimentary systems can yield first-order insights into the mechanics of surface processes and their deposits. This session welcomes diverse contributions that center variability and aim to demonstrate, characterize, and understand its role in governing surface processes and their depositional products. We encourage submissions that integrate theoretical, experimental, numerical, and field analyses to address stochastic and probabilistic elements of landscapes, sediment transport, and sedimentary records.