The Landscapes into Rock conference held in London this past week had four main themes. For more general information about the event, see my previous posts.
The first conference theme was "The Erosional Engine". The session was chaired by Alex Whittaker (Imperial College London) and Andrew Carter (Birkbeck College London) and focused on geomorphology, erosion, sediment flux, burial/exhumation histories. The theme had eight contributions in the form of presentations and two keynote speakers: Niels Hovius from University of Cambridge and Kelin Whipple from University of Arizona. Several posters were also on display.
One of the highlights for me was the talk by Paul Bierman et al (University of Vermont) on their synthesis of the ten-year research in erosion and sediment rates using cosmogenic nuclides, with one big takeaway being the fact that bedrock erosion rates (measured from outcrop along ridgelines) are slower than basin-scale erosion rates inferred from fluvial sediment; the latter integrates processes active across the entire landscapes. Interesting also was the positive correlation between tectonic setting/activity and erosion rates and the documentation of using cosmogenic nuclides as tracers to study processes over 10 to 10^5 years timescale.
The keynote address by Niels Hovius on weathering, erosion and sediment transfer in Taiwan, was another highlight, with a valuable insight into the fact that to get a better understanding of weathering and erosion it is more useful to look at the dynamic forces acting upon a landscape (tectonics, erosion, climate), rather than at the static proxies such as topography or landscape. Both Niels and Paul referred to mountains as being “big piles of sand”, which stirred a big debate during the discussion sessions.
Kelin Whipple’s keynote talk on tectonic and climatic control on erosion rates made some excellent points: at steady state conditions, tectonic is the major control on erosion (not climate). For non-steady state conditions, some generalizations arise regarding the ability to distinguish between the tectonic or climatic forcing, with erosion rates increasing gradually in response to tectonic forcing, versus erosion rates increasing immediately in response to climate forcing.