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Stream capture and the geomorphic evolution of the Linville Gorge in the southern Appalachians, USA
Geomorphology ( IF 3.9 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.geomorph.2020.107360
Bradley Johnson

Abstract The Linville River, in the Blue Ridge of North Carolina, flows across the Blue Ridge Escarpment and through Linville Gorge, a unique topographic feature within the southern Appalachians. The upper portion of the drainage effectively shifts the Eastern Continental Divide away from the escarpment crest. This shift is similar to other locations along the escarpment where streams flowing towards the Piedmont have captured drainage area from low-relief streams that drain towards the west. Here, we examine the upper Linville River for evidence of drainage captures that would have shifted drainage area away from the Toe River and into the Linville River. We used LiDAR data to reconstruct stream profiles for possible drainage pathways and examined cobble deposits near the headwaters of the North Toe River. Within those deposits on the west side of the Linville River, we found quartzite cobbles that must have been sourced from bedrock exposed only on the east side of the modern Linville River. This indicates that portions of the Linville Valley above Linville Falls historically drained to the west into the North Toe River. Headward erosion above Linville Falls resulted in downcutting and multiple stream captures. These captures more than tripled the drainage area of the Linville River, which would have significantly increased discharge downstream. This increase in discharge likely drove the geomorphic evolution of the modern Linville Gorge including resultant downcutting and associated hillslope processes and helps to explain the prominence of Linville Gorge.

中文翻译:

美国阿巴拉契亚山脉南部林维尔峡谷的溪流捕获和地貌演化

摘要 位于北卡罗来纳州蓝岭的林维尔河穿过蓝岭悬崖,流经林维尔峡谷,这是阿巴拉契亚山脉南部独特的地形特征。排水系统的上部有效地将东部大陆分水岭从悬崖顶移开。这种转变与悬崖沿线的其他位置相似,流向山麓的溪流从向西流淌的低地势溪流占据了流域。在这里,我们检查了 Linville 河上游的排水捕获证据,这些捕获可能会将流域从 Toe 河转移到 Linville 河中。我们使用激光雷达数据重建可能的排水路径的河流剖面,并检查了北脚趾河源头附近的鹅卵石沉积物。在林维尔河西侧的这些沉积物中,我们发现了石英岩鹅卵石,它们一定来自仅在现代林维尔河东侧暴露的基岩。这表明林维尔瀑布上方的林维尔山谷部分历史上向西排入北脚趾河。林维尔瀑布上方的上游侵蚀导致下切和多条河流捕获。这些捕获量使林维尔河的流域面积增加了两倍多,这将显着增加下游的排放量。这种流量的增加可能推动了现代林维尔峡谷的地貌演化,包括由此产生的下切和相关的山坡过程,并有助于解释林维尔峡谷的突出地位。我们发现石英岩鹅卵石一定来自仅暴露在现代林维尔河东侧的基岩。这表明林维尔瀑布上方的林维尔山谷部分历史上向西排入北脚趾河。林维尔瀑布上方的上游侵蚀导致下切和多条河流捕获。这些捕获量使林维尔河的流域面积增加了两倍多,这将显着增加下游的排放量。这种流量的增加可能推动了现代林维尔峡谷的地貌演化,包括由此产生的下切和相关的山坡过程,并有助于解释林维尔峡谷的突出地位。我们发现石英岩鹅卵石一定来自仅暴露在现代林维尔河东侧的基岩。这表明林维尔瀑布上方的林维尔山谷部分历史上向西排入北脚趾河。林维尔瀑布上方的上游侵蚀导致下切和多条河流捕获。这些捕获量使林维尔河的流域面积增加了两倍多,这将显着增加下游的排放量。这种流量的增加可能推动了现代林维尔峡谷的地貌演化,包括由此产生的下切和相关的山坡过程,并有助于解释林维尔峡谷的突出地位。这表明林维尔瀑布上方的林维尔山谷部分历史上向西排入北脚趾河。林维尔瀑布上方的上游侵蚀导致下切和多条河流捕获。这些捕获量使林维尔河的流域面积增加了两倍多,这将显着增加下游的排放量。这种流量的增加可能推动了现代林维尔峡谷的地貌演变,包括由此产生的下切和相关的山坡过程,并有助于解释林维尔峡谷的突出地位。这表明林维尔瀑布上方的林维尔山谷部分历史上向西排入北脚趾河。林维尔瀑布上方的上游侵蚀导致下切和多条河流捕获。这些捕获量使林维尔河的流域面积增加了两倍多,这将显着增加下游的排放量。这种流量的增加可能推动了现代林维尔峡谷的地貌演化,包括由此产生的下切和相关的山坡过程,并有助于解释林维尔峡谷的突出地位。
更新日期:2020-11-01
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