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Few modern sediment dispersal pathways predate the breakup of Pangea. This suggests that river lifespan can be controlled by continental assembly and dispersal cycles, with the longest-lived river systems present during supercontinent regimes. Based on the strikingly similar age spectra and Hf isotopic array extracted from Paleozoic to early Mesozoic sedimentary sequences from the Paleo-Tethyan margin basins, we argue that a long-lived supercontinental- scale system, with headwaters originating in Antarctica, flowed northward to finally debouch on the margin with the Paleo-Tethys Ocean. Channel-belt thickness scaling relationships, which provide an estimate of drainage area, support the notion that this was a supercontinental-scale system. Sediments were eroded from Proterozoic orogenic belts and flanked resistant kernels of Archean cratons. Remnants of this system, which can still be traced today as topographic lows, controlled post-breakup drainage patterns in Gondwanan fragments in Western Australia. We conclude that supercontinental regimes allow sediment dispersal systems to be long-lived, as they provide both an abundant sediment supply, due to erosion of large-scale, collision-related internal mountain systems, and a stable, large-scale configuration that lasts until breakup. [ABSTRACT FROM AUTHOR]

We used 10Be and 26Al to constrain the millennial-scale sediment and nuclide budget for a common, long-studied, but poorly understood landform in arid regions, the desert piedmont. We sampled the Chemehuevi Mountain piedmont, a complex multisurfaced landform in the Mojave Desert, western United States. The nuclide data indicate that sediment is produced more rapidly (1.1 × 105 kg·yr-1·.km-2) in steep mountain source basins than on the low-gradient pediment (4.0 × 104 kg·yr-1·km-2) or the intrapiedmont mountain range (2.5 × 104 kg·yr-1·km-2). However, the bulk of the sediment in transport is derived from erosion of the large abandoned alluvial surface (3.9 × 104 kg·yr-1·km-2). The combination of mass and nuclide budgeting suggests that sediment transport speeds decrease downslope from tens of meters per year in confined channels on the proximal pediment to decimeters per year in unconfined distributaries on distal wash surfaces. The sediment and nuclide budgeting approach we use is particularly valuable in arid regions where geomorphically significant events are infrequent and dating control is poor, thus confounding traditional sediment-budgeting techniques. [ABSTRACT FROM AUTHOR]

The article discusses the impact of large-magnitude sediment flows on the shape of landscapes. It references the study "Exhumation by Debris Flows in the 2013 Colorado Front Range Storm" by S. W. Anderson et al. published within the issue. It also compares the results of the study with other studies that compared net sediment transport from large debris-flow events and long-term erosion rates.