Sedimentologic and geomorphic variations in storm-generated alluvial fans, Howgill Fells, northwest England

Wells, Stephen; Harvey, Adrian

doi:10.1130/0016-7606(1987)98<182:sagvis>2.0.co;2

Cited by 248 publications

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“…Ces cônes de déjection résultent d'écoulements torrentiels en nappe, d'écoulements hyperconcentrés ou d'écoulements intermédiaires entre les deux premiers types (Lafortune et al, 2006). En règle générale, les cônes formés par ces types de dépôts se forment rapidement lors d'orages violents (Harvey, 1986 ;Blair, 1987 ;Wells et Harvey, 1987 ;Ballantyne et Whittington, 1999 ;Blair, 1999 Location of the Lake Guillaume-Delisle area and of the two study sites. Place names mentioned in the text are also indicated.…”

Section: Région Et Sites D'étudeunclassified

Émersion des terres et développement des sols bien drainés au lac Guillaume-Delisle, Québec subarctique

Lafortune

Filion

Hétu

2007

gpq

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Dans la région du lac Guillaume-Delisle, au Québec subarctique, des cônes de déjection d’âge et d’altitude variables se sont déposés tout au cours de l’Holocène sur des plages soulevées, offrant ainsi la possibilité d’étudier une chronoséquence holocène de sols. Le cadre temporel a été établi par la datation radiocarbone de 38 horizons organiques enfouis et la mise à jour de la courbe d’émersion des terres pour la région. L’émersion se serait effectuée selon un taux moyen de 5,6 m/siècle entre 8500 et 4500 années cal. BP et de 1,2 m/siècle après 4500 années cal. BP. Les analyses morphologiques et chimiques ont montré que les sols et paléosols subarctiques sableux, bien drainés et soustraits à l’influence des combes à neige, sont formés principalement par l’accumulation dans l’horizon B de matière organique humifiée combinée à de l’aluminium et du fer (podzolisation). L’enrichissement de l’horizon B en fer et en aluminium se fait lentement en suivant une fonction linéaire. La durée de pédogenèse requise pour obtenir le seuil minimal (Fep+Alp) de 0,4 % pour l’horizon Bf fixé par le Système canadien de classification des sols serait d’environ 12 400 années. Bien que théorique, cette durée indique à quel point les conditions nécessaires à la formation des podzols sont difficiles à réunir dans les sols subarctiques où la végétation demeure basse et le couvert nival peu épais.In the Lake Guillaume-Delisle area, alluvial fans of various ages and elevations were deposited throughout the Holocene over raised beach deposits, which allowed the studying of a subarctic soil chronosequence. The temporal framework is based on 38 14C dates obtained from buried organic soil horizons, and on an update of the Lake Guillaume-Delisle emersion curve. Postglacial uplift due to glacio-isostatic rebound occurred at a mean rate of 5.6 m/century from 8500 to 4500 cal. yr BP, and of 1.2 m/century after 4500 cal. yr BP. Soil morphology and chemistry showed that well-drained sandy soil and paleosoil development, when not influenced by late-lying snowpatches and snowmelt, is characterized by B horizons having a dominant accumulation product of amorphous material composed mainly of humified organic matter combined with Al and Fe (podzolisation). However, pedogenic development is weak and would take about 12 400 years to reach the minimum values of (Fep+Alp) ≥0,4% required for meeting the criteria of a Bf horizon in the Canadian system of soil classification, according to a linear function. Although theoretical, this value indicates that conditions required for Podzol formation are hard to reach in subarctic soils with low vegetation and thin snow cover

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Section: Région Et Sites D'étudeunclassified

Émersion des terres et développement des sols bien drainés au lac Guillaume-Delisle, Québec subarctique

Lafortune

Filion

Hétu

2007

gpq

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“…Given material to transport from steeplands and sufficient water for transport, alluvial fan deposition has been attributed to a wide variety of climatic conditions. From a slope stability perspective, the observation that infrequent, high-intensity storms trigger widespread erosion by overland flow and landsliding is well established in a variety of environments (Katzer et al, 1976;Caine, 1980;Wells and Harvey, 1987;Cannon, 1988;Montgomery et al, 2000). Furthermore, research has demonstrated that sediment aggrades on alluvial fans during extreme events, including hurricanes, under wet and cool climate regimes (Pierce and Scott, 1982;Kochel and Johnson, 1984;Ritter et al, 1995Ritter et al, , 2000.…”

Section: Connectivity Between Hillslope Fluvial and Alluvial Fan Prmentioning

confidence: 99%

Holocene landscape response to seasonality of storms in the Mojave Desert

Miller

Schmidt

Mahan

et al. 2010

Quaternary International

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Rene, "Holocene landscape response to seasonality of storms in the Mojave Desert" (2010 Periods of alluvial fan aggradation across the Mojave Desert are 14-9 cal ka and 6-3 cal ka. This timing largely correlates to times of increased sea-surface temperatures in the Gulf of California and enhanced warm-season monsoons. This correlation suggests that sustained alluvial fan aggradation may be driven by intense summer-season storms. These data suggest that the close proximity of the Mojave Desert to the Pacific Ocean and the Gulf of California promotes a partitioning of landscape-process responses to climate forcings that vary with seasonality of the dominant storms. Coolseason Pacific frontal storms cause river flow, ephemeral lakes, and fan incision, whereas periods of intense warm-season storms cause hillslope erosion and alluvial fan aggradation. The proposed landscape-process partitioning has important implications for hazard mitigation given that climate change may increase sea-surface temperatures in the Gulf of California, which indirectly could increase future alluvial fan aggradation.

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“…The importance of sheetflood processes as opposed to channelized fluvial processes has been recognized on desert alluvial fans (Blair & McPherson 1994a), and there is growing recognition of the distinctions within massflow processes between true debris-flow processes and those associated with hyperconcentrated flows (Wells & Harvey 1987;Blair & McPherson 1994a Kostaschuk et al 1986), it is realized that distinct fan surface gradients result from different depositional processes, but the concept of a specific 'slope gap' (Blair & McPherson 1994b) between alluvial fan and river gradients has since been demonstrated to have been flawed (Kim 1995;McCarthy & Candle 1995;Harvey 2002c;Saito & Oguchi 2005). To some extent Blair & McPherson's (1994a) classification of alluvial-fan styles, based on process combinations, reinforces the traditional concept of 'wet fans and dry fans' (Schumm 1977); however, the application of that concept to a climatic association with humid and arid climates, respectively, is clearly oversimplistic.…”

Section: Processes On Alluvial Fansmentioning

confidence: 99%

“…Scales may range from small debris cones (<50 m in length: e.g. Wells & Harvey 1987;Brazier et al 1988;Harvey & Wells 2003) to fluvially dominated megafans (up to 60 km in length: Gohain & Parkash 1990). Alluvial fans, although common in desert mountain regions (Harvey 1997), may occur in any climatic environment, in arctic (e.g.…”

mentioning

confidence: 99%

Alluvial fans: geomorphology, sedimentology, dynamics — introduction. A review of alluvial-fan research

Harvey

Mather

Stokes

2005

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Sedimentologic and geomorphic variations in storm-generated alluvial fans, Howgill Fells, northwest England

Cited by 248 publications

References 0 publications

Émersion des terres et développement des sols bien drainés au lac Guillaume-Delisle, Québec subarctique

Émersion des terres et développement des sols bien drainés au lac Guillaume-Delisle, Québec subarctique

Holocene landscape response to seasonality of storms in the Mojave Desert

Alluvial fans: geomorphology, sedimentology, dynamics — introduction. A review of alluvial-fan research

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