Dear all,
We are very pleased to announce the next Landscapes Live online seminar of the fall 2021 block by Abigail Langston (Kansas State University) that will occur on Thursday October 21st at 4pm CEST / 2 pm GMT / 7 am PST / 10 am EDT on:
"Beyond lithologic control of bedrock valley width: Characterizing the role of persistent valley cover in bedrock valley width development with examples from the field and the flume" (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). Register in advance for this meeting: https://wvu.zoom.us/meeting/register/tJwuf-2rpz0tGtJTUsz8Ft8vXXKMjjnxka_k (after registering, you should receive a confirmation email containing information about joining the meeting).
- 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: Research progress on lateral bedrock erosion, the first step in bedrock valley widening, lags far behind that of vertical incision. Lateral erosion has only recently received focused research. The second step of valley widening, the evacuation of collapsed bedrock material away from the valley wall, has been previously underappreciated as a control on bedrock valley widening rates. Recently, two end members of valley width development were identified (Langston and Temme, 2019). These end members are characterized by the persistence vs. mobility of collapsed bedrock wall material. In the two end members, collapsed material either 1) protects the valley wall and halts continued lateral valley widening or 2) is relatively rapidly transported away, allowing uninterrupted valley widening. Earlier work suggests that these two end members are at least as important as lithology in controlling valley width (Langston and Temme, 2019); however, this conceptual model of bedrock valley development is almost completely uncharacterized.I will present data from three studies that begin to explore processes of wide bedrock valley development. I will present findings from the first set of flume experiments focused on evaluating the conditions necessary to create wide bedrock valleys. The main takeaways from this set of flume experiments were that valley widening can be easily perturbed and shift to rapid vertical incision and that sediment on the bed is necessary but insufficient for the development of wide bedrock valleys. I will then discuss results from a field study of a small bedrock stream in northeast Kansas as an example of how lateral bedrock erosion and valley widening are linked (Marcotte et al., 2021). We measured rapid lateral erosion (in excess of 15 cm/year) in limestone and shale bedrock and observed several cases of bedrock bank collapse into the stream bed that were characteristic of the valley widening end members. The third stop will be the Buffalo River in northwest Arkansas, which is an ideal field site for characterizing valley widening end members. Distinct lithologies give rise to both wide and narrow bedrock valleys along our study reach, but bedrock "hardness" does not explain the differences in valley width. I will present data from this new project that characterizes collapsed wall material in wide and narrow bedrock valleys and the ability of the river to transport this collapsed material. Parameters that can be measured or estimated from field sites may provide a new metric for characterizing valley widening end members.
