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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Local topography and erosion rate control regolith thickness along a ridgeline in the Sierra Nevada, California
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Local topography and erosion rate control regolith thickness along a ridgeline in the Sierra Nevada, California

机译：加利福尼亚内华达山脉沿山脊线的局部地形和侵蚀速率控制go石厚度

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摘要

The ridgelines of mountain ranges are a source of geomorphic information unadulterated by the arrival of sediment from upslope. Studies along ridgecrests, therefore, can help identify and isolate the controls on important regolith properties such as thickness and texture. A 1.5km section of ridgeline in the Sierra Nevada (CA) with a tenfold decrease in erosion rate (inferred from ridgetop convexity) provided an opportunity to conduct a high-resolution survey of regolith properties and investigate their controls. We found that regolith along the most quickly eroding section of the ridge was the rockiest and had the lowest clay concentrations. Furthermore, a general increase in regolith thickness with a slowing of erosion rate was accompanied by an increase in biomass, changes in vegetation community, broader ridgeline profiles, and an apparent increase in total available moisture. The greatest source of variation in regolith thickness at the 10-100m scale, however, was the local topography along the ridgeline, with the deepest regolith in the saddles and the thinnest on the knobs. Because regolith in the saddles had higher surface soil moisture than the knobs, we conclude that the hydrological conditions primarily driven by local topography (i.e. rapid vs. slow drainage and water-storage potential) provide the fundamental controls on regolith thickness through feedbacks incorporating physical weathering by the biota and chemical weathering. Moreover, because the ridgeline saddles are the uppermost extensions of first-order valleys, we propose that the fluvial network affects regolith properties in the furthest reaches of the watershed. Copyright (c) 2015 John Wiley & Sons, Ltd.
机译：山脉的山脊线是地貌信息的来源，不受上坡沉积物到达的影响。因此，对山脊的研究可以帮助识别和隔离对重灰岩特性（例如厚度和质地）的控制。内华达山脉（CA）的山脊线长1.5公里，侵蚀速率下降了十倍（由山脊凸度推断），这为进行高岭土属性的高分辨率调查和研究其控制提供了机会。我们发现，沿山脊侵蚀最迅速的部分的重新碎石最坚硬，黏土浓度最低。此外，随着侵蚀速率的降低，硬石膏厚度普遍增加，同时生物量增加，植被群落发生变化，山脊轮廓更宽，总可用水分明显增加。然而，在10-100m范围内，背go石厚度变化的最大来源是沿山脊线的局部地形，鞍座中的背go石最深，旋钮上最薄。由于马鞍中的go石具有比旋钮更高的表层土壤湿度，因此我们得出结论，主要由局部地形驱动的水文条件（即快速排水与缓慢排水和蓄水潜力）通过结合物理风化的反馈提供了对go石厚度的基本控制。受生物区系和化学风化作用。此外，由于山脊线鞍是一阶河谷的最高延伸，我们建议河流网络影响该流域最远区域的re石性质。版权所有（c）2015 John Wiley＆Sons，Ltd.

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