Research

Earth Surface Processes Laboratory

University of Oregon

A sample of on-going projects...

Bedrock channel incision of Holocene lava flows

In the Oregon Cascade Range, spring-dominated river channels traverse lava flows of varying age, incising bedrock at rates that vary with slope and bedrock (i.e., lava flow) properties. We use airborne LiDAR and detailed field observations to quantify channel downcutting and document the mechanics of incision.

Modeling landscape evolution and sediment production with high-resolution topographic data

We use airborne LiDAR data to quantify the rates and mechanisms of sediment transport on hillslopes. Processes driving this movement include landslides, overland flow, soil creep via bioturbation, post-fire dry ravel (bouncing, rolling, and sliding of particles), and others. These investigations have implications for the evolution of mountainous terrain as well as land management policy.

For a 2006 GSA talk video, follow this link

Documenting patterns of paleo-landslide style and deformation history using statistical analysis of airborne laser altimetry data: New Zealand and Northern California.

Hillslopes in most mountainous landscapes are prone to large bedrock landslides. It is difficult to constrain whether pre-historic episodes of slope instability reflect seismic activity, wet climatic periods, increased rates of channel incision, or other mechanisms. Detailed morphologic mapping of paleo-landslides using airborne lidar data reveals a rich suite of surface forms that can be quantified using various statistical analyses. Most generally, recent failures exhibit fresh scarps and deformation features that become increasingly subdued with time. By calibrating our statistical analyses with field-based data constraining landslide age, we hope to generate maps illustrating the timing and style of slope failure across entire drainage basins.

Ben Mackey webpage

Quantifying the biological contribution to soil production and transport

Geomorphologists have long suspected that biotic processes may play a significant role in the weathering of bedrock and transport of soil, little evidence exists to support this notion. We are using a suite of tools, including: ground-penetrating radar, airborne LiDAR, geochemical tracers, and biological analyses, to document and quantify biological influences on hillslope processses. In particular, we are investigating the role of tree-driven bioturbation as a soil production mechanism in steep-forested landscapes.

Post-fire erosion geomorphic response

Fire fundamentally alters landscape function. Fires often trigger a suite of geomorphic processes that transmit high sediment yields to nearby streams, degrading aquatic habitat and endangering human life.  Preliminary data in the Oregon Coast Range suggest transport by dry ravel dominates geomorphic response to the extent that the soil mantle is preferentially stripped revealing wide swaths of bedrock. Using LiDAR data, we plan to develop predictive models for mapping the location and magnitude of sediment delivery following fire events.  In addition, we will use our models to reconcile millennial-scale fluctuations in sediment delivery with long-term fire frequency records documented from lake cores. These studies will enable us to quantitatively link modern process rates with fluctuations revealed in sedimentary deposits.

Soils as a reflection of landscape adjustment

The development of soils depends on climatic and tectonic processes as well as time. In an erosional landscape, soil properties vary with topographic position as well as local baselevel control. We are using traditional and new techniques to quantify the variability of soil properties as a reflection of drainage capture, differential uplift, and deep-seated landsliding. Collaboration with Peter Almond (Lincoln University).

AGU Poster from 2008 Annual Meeting