Highlight articles

U–Th and 10Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia

Sediments produced by glaciers are transported by rivers and wind toward the ocean. During their journey, these sediments are weathered, and we know that this has an impact on climate. One key factor is time, but the duration of this journey is largely unknown. We were able to measure the average time that sediment spends only in the glacial area. This time is 100–200 kyr, which is long and allows a lot of processes to act on sediments during their journey.

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

The layer known as the critical zone extends from the tree tops to the groundwater. This zone varies globally as a function of land use, climate, and geology. Energy and materials input from the land surface downward impact the subsurface landscape of water, gas, weathered material, and biota – at the same time that differences at depth also impact the superficial landscape. Scientists are designing observatories to understand the critical zone and how it will evolve in the future.

Seismic monitoring of small alpine rockfalls – validity, precision and limitations

We use a seismometer network to detect and locate rockfalls, a key process shaping steep mountain landscapes. When tested against laser scan surveys, all seismically detected events could be located with an average deviation of 81 m. Seismic monitoring provides insight to the dynamics of individual rockfalls, which can be as small as 0.0053 m³. Thus, seismic methods provide unprecedented temporal, spatial and kinematic details about this important process.

Efficient retention of mud drives land building on the Mississippi Delta plain

Our work presents a novel method of measuring the capacity of deltaic landforms to trap and retain river-borne sediments, and we demonstrate that sediment retention is closely connected to sedimentary composition. Our results, supported by a unique high-resolution coring dataset in a major crevasse splay, show that finer sediments are a much larger component of the Mississippi Delta than is often acknowledged and that their abundance indicates exceptionally high rates of sediment retention.

Geomorphometric delineation of floodplains and terraces from objectively defined topographic thresholds

Floodplains and fluvial terraces can provide information about current and past river systems, helping to reveal how channels respond to changes in both climate and tectonics. We present a new method of identifying these features objectively from digital elevation models by analysing their slope and elevation compared to the modern river. We test our method in eight field sites, and find that it provides rapid and reliable extraction of floodplains and terraces across a range of landscapes.

Graffiti for science – erosion painting reveals spatially variable erosivity of sediment-laden flows

Spatial bedrock erosion data from stream channels are important for engineering issues and landscape evolution model assessment. However, acquiring such data is challenging and only few data sets exist. Detecting changes in repeated photographs of painted bedrock surfaces easily allows for semi-quantitative conclusions on the spatial distribution of sediment transport and its effects: abrasion on surfaces facing the streamflow and shielding of surfaces by abundant sediment.

Oxidation of sulfides and rapid weathering in recent landslides

Rapid dissolution of bedrock and regolith mobilised by landslides can be an important control on rates of overall chemical weathering in mountain ranges. In this study we analysed a number of landslides and rivers in Taiwan to better understand why this occurs. We find that sulfuric acid resulting from rapid oxidation of highly reactive sulfides in landslide deposits drives the intense weathering and can set catchment-scale solute budgets. This could be a CO₂source in fast-eroding mountains.

Gravel threshold of motion: a state function of sediment transport disequilibrium?

Accurately predicting gravel transport rates in mountain rivers is difficult because of feedbacks with channel morphology. River bed surfaces evolve during floods, influencing transport rates. I propose that the threshold of gravel motion is a state variable for channel reach evolution. I develop a new model to predict how transport thresholds evolve as a function of transport rate, and then use laboratory flume experiments to calibrate and validate the model.

Efficacy of bedrock erosion by subglacial water flow

In regions formerly, or currently, covered by glaciers, landscapes have largely been shaped by glaciers. Glaciers erode bedrock through three main mechanisms: abrasion, quarrying, and subglacial meltwater erosion (SME). The latter, however, remains enigmatic. We present the first numerical modelling study of bedrock erosion by subglacial water and find that SME is negligible compared to abrasion and quarrying across the glacier, but its localization can explain the formation of bedrock channels.

Grain sorting in the morphological active layer of a braided river physical model

A physical scale model of a gravel-bed braided river was used to measure vertical grain size sorting in the morphological active layer defined as the bed material between the maximum and minimum bed elevation. By normalizing active layer thickness and dividing into 10 sublayers we show that all grain sizes occur with almost equal frequency in all sublayers. Occurrence of patches and strings of coarser material relates to preservation of particular morphotextural features within the active layer.

News & press Highlight articles

Highlight articles

Information for

External links