ABRASION, DISSOLUTION, AND THE EVOLUTION OF SCALLOPED FEATURES IN ROCKS

Cave passages contain rills, potholes, flutes, scallops, sediment deposits, cracked, and broken rocks. These features indicate erosion of bedrock by chemical and physical processes and can be interpreted to describe hydrological and mechanical conditions at the time of cave passage formation. Uniquely situated and shielded from further erosion by forces on earth’s surface, caves can preserve these features for long periods of time. The work presented here focuses primarily on scallops in bedrock walls of caves. Although scallops are not seen on all cave passage walls, they are common and thus receive much attention in speleological literature. Scalloped rocks in caves are frequently found near sediment deposits. The proximal association of these two features may suggest that sediment transport and water flow play a synergistic role in scallop formation. The combined contributions from abrasion and dissolution likely determine the size, shape, and frequency of scallops and thus influence the way we could analyze these features to interpret flow and sediment transport conditions present when the scallops formed. In this work, scalloped rocks and bedrock surfaces, along with sediment deposits and present-day water flow rates are used to characterize conditions in which scallops likely form. At each field site, structure from motion or lidar 3D reconstruction is used to create geometric representations of the scallop features and surrounding areas. Computational fluid dynamics and numerical models of water flow, dissolution, and sediment transport within the geometric representations are used to investigate the landscape evolution of caves and evaluate the relative contributions from abrasion and dissolution cave passage evolution.