GEOMORPHIC RECORDS OF LITHOSPHERIC PROCESSES: CASE STUDIES IN THE NORTH AND SOUTH AMERICAN CORDILLERA (Invited Presentation)

Topographic evolution is result of lithospheric processes that generate positive relief and the climatic driven processes that reduce it. In this talk, I provide a general overview of how landscapes and geomorphic landforms respond to and record lithospheric processes. We cover how and why some signals get shredded due to complexities within the geomorphic system while others remain in the landscape over long timescales. We provide specific examples of landscape signatures of rock-uplift patterns in central Idaho of the northern U.S. Cordillera and in southwestern Peru of the Andes. Both locations have large, deep canyons cutting terrain elevated by broad wavelength rock-uplift; yet the timing of these rock-uplift events are either poorly constrained or contentious. We focus on quantifying the geomorphic response of tributaries to mainstem canyon incision. We argue that this approach increases the robustness of interpreting geomorphic signatures in the landscape because the tributaries isolate single rock-types and climate, two factors that are often responsible for shredding tectonic signatures in topography. The magnitude of transient incision in these tributaries is related to the local rate of rock-uplift, rather than long wavelength patterns in rock uplift. By piecing together tributaries across these regions, we can constrain spatiotemporal patterns of rock-uplift and the geodynamic drivers responsible for surface uplift in these different orogens. Our work provides another example of how interdisciplinary approaches that connect the surface to deeper lithospheric and mantle processes help understand the dynamic Earth system interactions that shape the Earth’s surface.