Enduring legacy of toxic fans: Episodic redistribution of California gold mining debris
Michaerl Singer (University of St Andrews)
Friday 8th February at 16:00 in the East Quadrangle Lecture Theatre
Abstract: The interrelationships between hydrologically driven evolution of legacy landforms downstream of major mining districts and the contamination of lowland ecosystems are poorly understood over decadal to centennial timescales. Here we demonstrate that 19th Century gold mining anthropogenic fans, remaining within Sierra Nevada piedmont valleys of California, comprise a persistent yet episodic source of Hg to lowlands. We document: 1) a recent shift in fan evolution from rapid vertical channel entrenchment to pervasive lateral erosion of historical terraces, thus enabling entrainment of large volumes of Hg-laden sediment during erosion episodes; and 2) systematic internal redistribution and downstream progradation of fan sediment into the Central Valley, triggered by erosion of historical mining terraces during increasingly long, 10-year flood events. Each major flood evacuates <<1% of the total stored sediment in the Yuba Fan, and delivers huge Hg masses to sensitive lowlands, equivalent to ~10-30% of the entire post-mining Sierran Hg mass conveyed to the San Francisco Bay-Delta (SFBD). This process of protracted, but punctuated exhaustion of legacy sediment and associated Hg is likely to persist for >10⁴ years.It creates, within an immense swathe of river corridor well upstream of the SFBD, new contaminated floodplain surfaces primed for Hg methylation and augments/replenishes potential Hg sources to the SFBD. We conclude that anticipation, prediction, and management of toxic sediment delivery and corresponding risks to lowland ecology and human society depend on the morphodynamic stage of anthropogenic fan evolution, synergistically coupled to the increasing frequency and duration of extreme floods.
Military aircraft noise and the politics of spatial affect in Okinawa
Rupert Cox (University of Manchester)
Friday 15th February at 15:30 in the East Quadrangle Lecture Theatre
'Tek bad ting make laugh': the multiple materialities of Caribbean laughter
Pat Noxolo (University of Sheffield)
Friday 1st March at 15:30 in the East Quadrangle Lecture Theatre
Greening stone conservation? Linking biodiversity and cultural heritage conservation
Heather Viles (University of Oxford)
Friday 8th March at 16:00 in the East Quadrangle Lecture Theatre
Abstract: Do plants and other biota provide a threat or an opportunity for the conservation of historic sites such as Angkor Wat and Tintern Abbey? And, in turn, can sites protected for heritage reasons also contribute to global biodiversity conservation by providing a refuge for important, rare or threatened species? Recent research is starting to allow a more balanced assessment of the opportunities and risks of allowing biotic communities to grow on walls and buildings. Evidence from research on barnacles and algae on coastal defence structures, green algae on sandstone walls, ivy on historic walls and soft capping of ruins provides clear examples of both positive and negative roles of biota and how positive roles might be enhanced.
Heather Viles is Professor of Biogeomorphology and Heritage Conservation in the School of Geography and Environment at the University of Oxford, UK. She runs the Oxford Rock Breakdown Laboratory (OxRBL). Her research focuses on stone deterioration and conservation in the built environment, and on rock breakdown in extreme environments (including rocky coasts, deserts and on Mars). She enjoys working in interdisciplinary teams, and is currently involved in projects with ecologists, microbiologists, engineers, geologists, archaeologists, stone masons, and architectural conservators in collaboration with English Heritage, the British Museum, Proceq, Queens University Belfast, Lanzhou University, China and the University of the Witwatersrand, South Africa.
Extreme sedimentology: A giant meteorite impact in the Mesoproterozoic of NW Scotland
Mike Simms (National Museums Northern Ireland)
Friday 12th April at 16:00 in the East Quadrangle Lecture Theatre
Abstract: Many commonplace sedimentological processes or events can be observed in the field or reproduced in the laboratory. Others, such as tsunamis, are rare and unpredictable events where chance observations by non-specialists may be as important as years of research by experts. Still other events are so rare that they have never been witnessed by humans and can only be investigated long after, and so extreme that we are still far from understanding them in detail. One such ‘ extreme sedimentary event’ is found in the Mesoproterozoic Stoer Group of north-west Scotland, where the 5-10 metre thick Stac Fada Member is now generally recognised as an ejecta deposit from the hypervelocity impact of a kilometre-scale meteorite. Just a narrow elongate outcrop of the ejecta deposit survives today, but it exemplifies the extreme processes involved in the emplacement of impact ejecta. The Stac Fada Member is similar to previously documented impact ejecta deposits in some respects, but unique in others. The impact occurred into a heterogeneous landscape of basement (Lewisian) inliers and thick (km-scale) waterlogged fluvial sediments, which strongly influenced the nature and distribution of the ejecta deposit. Large-scale sedimentary structures within the Stac Fada Member suggest that its source – the impact crater - lay to the east of the Stoer Group outcrop. The presence of a deep gravity low beneath the Moine Thrust at Lairg, due east of the Stoer Group outcrop, suggests that the crater itself may still survive.
Eve of biomineralisation
Rachel Wood (School of Geosciences, University of Edinburgh)
Friday 10th May at 16:00 in the East Quadrangle Lecture Theatre
Interaction between basin hydrology, sediment transport and stream channel adjustment in a mountainous stream, Pisco River, Peru
Toufik Bekaddour (University of Bern)
Wed 15th May at 16:14 in the East Quadrangle 414