Abstract

With homogeneous bedrock, dramatic climate gradients, and remnant surfaces that constrain their age, initial topography, and vertical motions relative to sea level, volcanic ocean islands provide an exceptional natural experiment in landscape evolution. Analyses traversing gradients in island climate and bedrock age have the potential to advance our understanding of climatic and tectonic influences on landscape evolution in a diverse range of continental settings. Yet, as net subsiding and boundary-dominated landmasses, islands are in some ways dissimilar to most continental landscapes, and the mechanisms of island vertical motion remain largely enigmatic. Island uplift and subsidence can provide important observational constraints on the rheology and dynamics of the Earth’s interior, in addition to setting the boundary conditions for the topographic, climatic, and biogeographic evolution of island landscapes. In this talk, I exploit steep climate gradients in the Hawaiian Islands to quantify controls on fluvial and coastal erosion, and I assess the contribution of lithosphere and mantle processes to surface deformation at ocean hotspots. Through physically-based modeling, analysis of topo-bathymetric and geochronologic data, and field measurements, I examine (1) the control of rainfall variability on long-term rates of bedrock river incision on the Hawaiian Island of Kaua’i, (2) the influence of wave power on bedrock coastal erosion in the Hawaiian Islands, and (3) the mechanisms that cause volcanic ocean islands to drown below sea level to form atolls and guyots. These analyses provide empirical support for hypothesized feedbacks between climate, tectonics, and topography, linking the evolution of the solid earth, hydrosphere, and biosphere.