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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Aeolian activity at a giant sandstone weathering pit in arid south-central Utah
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Aeolian activity at a giant sandstone weathering pit in arid south-central Utah

机译：干旱的犹他州中南部一个巨大的砂岩风化坑中的风成活动

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摘要

Aeolian abrasional, depositional and deflational features indicate exceptionally strong Southwesterly winds in a giant sandstone weathering pit in Grand Staircase Escalante Monument, about 22 kill southeast of Escalante, Utah. The 60 ill wide, 5-20 m deep pit has developed near the Summit of a broad, barren 160-m-high dome on the Lower Jurassic Navajo Sandstone. Unlike other giant weathering pits (10-30 m diameter) in the region, the bedrock floor of this pit is undulatory, and there is a cylindrical, 10-m-high rock pedestal in the centre of the pit. An active dune surrounds the central pedestal and at times has as much as 8 m of local relief. The dune shifts considerably over brief (< 1 year) periods of time. Fine-grained (< 250 mu m) dunal sand on the pit floor is periodically removed by deflation, leaving coarser sand (> 250 mu m) trapped in the pit. Dunal sand is typically derived from external sources (other than the pit walls and floor). Centimetre to metre-scale abrasional features Such as grooves, flutes and dedos occur on the bedrock walls and floor of the pit. These dedos and other streamlined aeolian Sculpted host-rock features occur in clusters and typically form in the lee of iron concretions. The dedos are similar to the controversial stalked blueberries oil Mars. Above the western rim of the pit there is a 29-m-long, 5-m-wide aeolian groove with a fluted bedrock floor. A 1.2-km-long bedrock valley descends to the Southwest from the pit and groove, amplifying southwesterly winds. Data from hand-held anemometers Suggest that southwesterly winds call be accelerated 200-300 per cent or more by local topography. Copyright (C) 2008 John Wiley and Soils, Ltd.
机译：风沙的擦蚀，沉积和变形特征表明，在大楼梯埃斯卡兰特纪念碑的巨型砂岩风化坑中，西南风偏强，大约在犹他州埃斯卡兰特东南约有22人丧生。在下侏罗纪纳瓦霍砂岩上一个广阔的，贫瘠的，160米高的圆顶顶峰附近，已经形成了60个病态，深5-20 m的深坑。与该地区其他大型风化坑（直径10-30 m）不同，该坑的基岩层是起伏不定的，并且坑中心有一个圆柱形的10 m高的岩石基座。活跃的沙丘围绕着中央基座，有时会产生多达8 m的局部起伏。在短暂的（<1年）时间内，沙丘会发生很大的变化。定期通过放气清除坑底的细粒（<250微米）沙质沙，将较粗的沙子（> 250微米）留在坑中。沙石通常来自外部资源（坑壁和地面除外）。厘米至米级的磨损特征，例如基坑壁和底坑上会出现沟槽，凹槽和斜角。这些dedos和其他简化的风成风雕刻的岩体特征成簇出现，通常形成于铁凝结物的下层。这种酒与争议性的蓝莓油火星相似。矿井西缘上方有一条长29米，宽5米的风沙沟，基岩带槽。一个1.2公里长的基岩谷从坑洼处向下延伸至西南，放大了西南风。手持式风速计的数据表明，西南风在当地地形的作用下可加快200-300％或更多。版权所有（C）2008 John Wiley and Soils，Ltd.

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