Multi-scale geomorphologic expressions of outcrop lithology in rocky intertidal habitats in Central-Northern California

Substratum geology is fundamental in shaping rocky shore morphology. Specific lithologies have various responses to wave action, tectonic features (e.g. fractures, faults) and sedimentary structures (e.g. bedding), creating distinctive multi-scale weathering profiles. By digitally capturing substrata surface morphology, it becomes possible to fingerprint individual rock types. This study presents results of multi-scale terrestrial laser scanning surveys from 10 rocky intertidal outcrops from central to northern California, representing the most common igneous, sedimentary, and metamorphic units along the coast. Analysis of surface morphology from 3D data using two surface roughness parameters and geological measurements made in situ support the hypothesis that surface properties can change significantly with changing scale, each rock type having distinct surface characteristics which are similar to comparable lithologies exposed at different locations. These distinct characteristics act as signatures within the rock, making the morphology predictable for outcrops along the California coast.