GREAT BIG BOULDERS AND LANDSCAPE SELF-ORGANIZATION
Boulders are produced on hillslopes by landsliding, rockfall, and exhumation through the critical zone. On hillslopes dominated by local sediment transport, boulders affect hillslope soil production and transport processes such that the downslope boulder size distribution sets the form of steady-state hillslopes. Hillslopes dominated by nonlocal transport are less likely to exhibit boulder controls on hillslope morphology as boulders are rapidly transported to the hillslope toe. Downslope transport delivers boulders to rivers where the boulders act as large roughness elements that change flow hydraulics and the efficiency of erosion and sediment transport. Over longer timescales, rivers adjust their shape to enableerosion at the baselevel fall rate given their boulder size distribution. The delivery of boulders from hillslopes to channelsdrives channel-hillslope feedbacks that affect landscape evolution and steady-state form. Boulders cause geomorphic hazards that can be mitigated with an improved understanding of boulder production and mobility. Opportunities for future work primarily entail field-focused data collection across gradients in tectonics, climate, and lithology with the goal of understanding boulder dynamics as one component of landscape self-organization.