Dear all,
We are very pleased to announce the second Landscapes Live online seminar of the fall 2021 block by Doug Jerolmack (University of Pennsylvania) that will occur on Thursday September 23th at 4pm CEST / 2 pm GMT / 7 am PST / 10 am EDT on:
"Landscapes of Glass" (see abstract at the end of this message)
This seminar will be live on Zoom and open to anyone interested (with a limit of 300 participants). You can register in advance for this Zoom meeting here: https://huji.zoom.us/meeting/register/tZ0qf-ispjoqEtdU5d11u7_M5T16VFQ-O1q_ (after registering, you should receive a confirmation email containing information about joining the meeting).
- Thursday 30th September at 2 pm GMT/ 4 pm CEST: Andrew Christ, University of Vermont
- Thursday 07th October at 2 pm GMT/ 4 pm CEST: Cristián Escauriaza, Pontificia Universidad Catolica de Chile
- Thursday 21st October at 2 pm GMT/ 4 pm CEST: Abigail Langston, Kansas State University
- Thursday 28th October at 2 pm GMT/ 4 pm CEST: Sara Savi, Potsdam University
- Thursday 04th November at 2 pm GMT/ 4 pm CEST: Katharine Huntington, University of Washington
- Thursday 18th November at 2 pm GMT/ 4 pm CEST: Dirk Scherler, GFZ Potsdam
- Thursday 25th November at 2 pm GMT/ 4 pm CEST: Anne Bernhardt, Freie Universität Berlin
- Thursday 02nd December at 2 pm GMT/ 4 pm CEST: Sébastien Carretier, IRD and University of Toulouse
More information on these talks as well as the videos of previous talks are available on our website (https://www.landscapeslive.org/).
Landscapes Live is the EGU Geomorphology Division's virtual webinar series focused on sharing exciting geomorphology research throughout the international scientific community. Feel free to contact us if you have questions or suggestions: landscapesliveseminar@gmail.com
Best wishes,
The Landscapes Live team: Rebekah Harries, Michal Ben-Isreal, Pierre Valla, Philippe Steer, Steffi Tofelde, Charlie Shobe, Vivi Pedersen and Boris Gailleton
Abstract: If cooled sufficiently quickly, the disorder of a liquid can be "quenched" or locked in place; the resulting amorphous solid is glass. Although it appears to be solid on human timescales, glass continues to creep due to thermal vibrations at the molecular scale. Consider now a pile of sand; it too is a disordered system, but the grains are too massive for such thermal effects to be relevant. Yet, soils in nature relentlessly creep, on hillslopes below the angle of repose. The unchallenged dogma is that this creep is driven by churning of soil by (bio)physical disturbances, and diffusion models based on this premise underpin virtually all landscape evolution models (LEMs). River-bed sediments also creep, at flows below the threshold of motion, though this has received far less attention. In this talk I focus on recent work from my group and others that examines the origins of granular creep in hillslope and river systems, and the consequences of these findings for landscape dynamics. Our observations, arising from first-of-their-kind experiments and simulations, reveal surprises for both geologists and physicists. First, gravity-driven granular creep occurs with minimal disturbance, with rates and styles comparable to field observations. Second, this creep shares deep similarities with the behavior of glass, suggesting that mechanical disturbance in granular systems plays a role akin to thermal fluctuations in molecular systems. Third, fluid-driven creep in bed-load systems has similar behavior to gravity-driven hillslope creep. In both cases this creep acts to "harden" the bed, by compaction and the creation of structures that resist motion. Thus, sediment beds maintain a memory of their history of forcing, that dicates the threshold for landsliding (hillslopes) or entrainment (rivers). I wish that I could conclude with some new model or models that would incorporate these insights and improve LEMs. But we're just not there yet. We're still in the process of deconstructing old models with challenging observations of what grains do. My hopes, then, are the following: introduce new concepts and frameworks from glass physics that I find helpful for understanding landscapes; engage broader interest (from you!) in HOW landscapes accomplish their deformation; explain qualitative phenomenology of natural landscapes; and get insights from you on "translating" these findings to systems you may care about (or, at least care about more than a pile of sand).
