Imperial College London
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DrDylanRood

Faculty of Engineering, Department of Earth Science & Engineering

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 7461d.rood

 
 
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Location

 

4.43Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Pacheco:2020:10.3389/feart.2020.00372,
author = {Pacheco, M and Plattner, AM and Stock, GM and Rood, DH and Pluhar, CJ},
doi = {10.3389/feart.2020.00372},
journal = {Frontiers in Earth Science},
pages = {1--12},
title = {Surface exposure dating and geophysical tomography of the royal arches meadow rock avalanche, Yosemite Valley, California},
url = {http://dx.doi.org/10.3389/feart.2020.00372},
volume = {8},
year = {2020}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Since the retreat of glaciers after the Last Glacial Maximum, rock avalanches haveoccurred intermittently in Yosemite Valley, California. We investigated the distal portionof the oldest of these, the Royal Arches Meadow rock avalanche, which has beenpartially buried by sediment aggradation. Cosmogenic 10Be exposure ages of boulderswithin the deposit indicate that the rock avalanche occurred at 16.1 ± 0.3 ka, immediatelyafter deglaciation and thus prior to most aggradation. The interface between the rockavalanche deposit and the underlying glaciofluvial sediments therefore provides anelevation marker of the valley floor at the time of deposition. To identify the elevationof this interface, we collected eight Ground Penetrating Radar (GPR) and five ElectricalResistivity Tomography (ERT) profiles across the rock avalanche. Both methods aresensitive to contrasts between the granitic avalanche deposit and the underlyingsediments. By constraining ERT inversions with GPR interfaces that are continuousacross the profiles, we identified a single interface, interpreted as the basal contact of therock avalanche, that separates resistive material from conductive material underneath.The elevation of this approximately horizontal interface is between 1,206 and 1,209m, roughly 10 m below the modern ground surface, indicating ≈ 10 m of sedimentaggradation since deglaciation. Based on topographic expression and depth to thiscontact, we determined a minimum volume estimate of between 8.1 × 105 m3 and9.7 × 105 m3, nearly three times larger than what would be estimated from surfaceexpression alone. Our findings allow reconstruction of the sedimentation history ofYosemite Valley, inform hazard and risk assessment, and confirm that geophysicalmethods are valuable tools for three-dimensional investigations of rock avalanches,particularly those buried by younger sediments.
AU  - Pacheco,M
AU  - Plattner,AM
AU  - Stock,GM
AU  - Rood,DH
AU  - Pluhar,CJ
DO  - 10.3389/feart.2020.00372
EP  - 12
PY  - 2020///
SN  - 2296-6463
SP  - 1
TI  - Surface exposure dating and geophysical tomography of the royal arches meadow rock avalanche, Yosemite Valley, California
T2  - Frontiers in Earth Science
UR  - http://dx.doi.org/10.3389/feart.2020.00372
UR  - https://www.frontiersin.org/articles/10.3389/feart.2020.00372/full
UR  - http://hdl.handle.net/10044/1/83277
VL  - 8
ER  -
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