Controls on the rates and products of particle attrition by bed-load collisions

Abstract. River rocks round through the process of impact attrition, whereby energetic collisions during bed-load transport induce chipping grain surface. This is also important for bedrock erosion. Although previous work has shown that energy, lithology, and shape are controlling factors attrition rates, functional dependence among these quantities not settled. Here we examine using a double-pendulum apparatus generates controlled between two grains under conditions relevant transport. We determine size distributions (GSDs) products. Two experimental results appear to support treatments erosion as brittle fracture: (i) mass loss proportional kinetic this proportionality function previously identified material properties; (ii) attrition-product GSDs well described by Weibull distribution. Chipping from development shallow surface-parallel cracks, distinct bulk fragmentation occurs at higher energies. suggest Hertzian fracture dominant mechanism identify an initial phase rapid in which independent energy effect associated with removal very sharp corners. The apparent universality both curves requires further investigation. Nonetheless, findings useful interpreting contribution in-stream downstream fining production sand resulting river pebbles.