This is an author-produced, peer-reviewed version of this article. AbstractThe Middle Fork Salmon River watershed spans high-elevation mixed-conifer forests to lowerelevation shrub-steppe. In recent decades, runoff from severely burned hillslopes has generated large debris flows in steep tributary drainages. These flows incised alluvial fans along the mainstem river, where charcoal-rich debris-flow and sheetflood deposits preserve a record of latest Pleistocene to Holocene fires and geomorphic response. Through deposit sedimentology and 14 C dating of charcoal, we evaluate the processes and timing of fire-related sedimentation and the role of climate and vegetation change. Fire-related deposits compose ~66% of the total measured fan deposit thickness in more densely forested upper basins versus ~33% in shrubsteppe-dominated lower basins. Fires during the middle Holocene (~8000 -5000 cal yr BP) mostly resulted in sheetflood deposition, similar to modern events in lower basins. Decreased vegetation density during this generally warmer and drier period likely resulted in lowerseverity fires and more frequent but smaller fire-related sedimentation events. In contrast, thick fire-related debris-flow deposits of latest Pleistocene-early Holocene (~13,500-8000 cal yr BP) and late Holocene (< 4000 cal yr BP) age are inferred to represent higher-severity fires, though data in the former period are limited. Widespread fires occurred in both upper and lower basins within the Medieval Climatic Anomaly (1050-650 cal yr BP) and the early Little Ice Age ca. 550 cal yr BP. We conclude that a generally cooler late Holocene climate and a shift to denser lodgepole pine forests in upper basins by ~2500 cal yr BP provided fuel for severe fires during episodic droughts.

Cosmogenic 10Be concentrations in alluvial sediment are widely used to infer long-term, catchment-averaged erosion rates based on the assumption that the landscape is in mass-flux steady state. However, many landscapes are out of equilibrium over millennial time scales due to tectonic and climatic forcing. The Grand Staircase of the Colorado Plateau (North America) is a transient landscape, adjusting to base-level fall from the carving of the Grand Canyon, and is characterized by cliff-bench topography caused by differential erosion of lithologic units. The 10Be concentrations from 52 alluvial and colluvial samples, collected in nested fashion from five catchments, produced inferred erosion rates ranging from 20 to >3500 m/m.y. (or mm/k.y.). We attribute this high variance in part to lithologic-controlled steepness and hotspots of erosion related to cliff retreat along the White Cliffs (escarpment near Mt. Carmel Junction, Utah), as well as headward drainage expansion along the uppermost Pink Cliffs (escarpment within Bryce Canyon National Park). Results from the downslope Vermillion Cliffs (near Kanab) indicate lower erosion rates despite similar slope and rock types, suggesting knick-zone migration has passed that lower region of our study area. The 10Be concentrations measured along trunk streams systematically match local, subcatchment erosion rates, with muted influence from upstream sediment sources. This is consistent with intermittent sediment conveyance between cliff and bench terrain, with sediment storage and localized release associated with ephemeral arroyo systems in the region. Therefore, while detrital cosmogenic nuclide records in transient landscapes may not directly reflect upstream catchment-averaged erosion rates, 10Be inventories can provide insight into unsteady upslope-directed erosion and downslope-directed sediment conveyance in these dynamic landscapes.

In this paper a series of 7 salalen ligands based on an aminopyrrolidine backbone have been prepared and characterised. Several systems have been reduced to the salan ONNO type-ligand. All ligands have been complexed to Al III with Al-(1-7)Me, Al(2a)(OiPr) and Al(7a)Me being characterised by single-crystal X-ray diffraction. In general the Al III centres are best described as being in a trigonal bipyramidal geometry. The solution and solid-state structures are discussed. All complexes [a]

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