Crag and tails (BRITICE glacial landforms)

A crag is a rocky hill or mountain, generally isolated from other high ground. Crags are formed when a glacier or ice sheet passes over an area that contains a particularly resistant rock formation (often granite, a volcanic plug or some other volcanic structure). The force of the glacier erodes the surrounding softer material, leaving the rocky block protruding from the surrounding terrain. Frequently the crag serves as a partial shelter to softer material in the wake of the glacier, which remains as a gradual fan or ridge forming a tapered ramp (called the tail) up the leeward side of the crag. About: This layer comes from Britice version two, which is updated since 2004. The imprint of the last ice sheet on Britain and Ireland has been studied for over 100 years. During this time, scientists conducting fieldwork and mapping from satellite data and aerial photography produced geomorphological (landform) maps, documenting the distribution of landforms left behind by the ice sheet. We reviewed over 1,800 publications from the academic literature, British Geological Survey and Irish Geological Survey mapping. For more details, please refer to the Britice website: https://sheffield.ac.uk/geography-planning/research/geography/projects/britice崖壁（crag）指孤立于其他高地之外的岩质山丘或山地。崖壁的形成源于冰川或冰盖流经一处分布有高强度抗侵蚀岩层（多为花岗岩、火山颈或其他火山构造）的区域：冰川的侵蚀作用会剥离周边松软物质，使得岩块突兀留存于周遭地貌之中。通常，冰川消退后遗留在崖壁背风坡的松软物质会依托崖壁形成缓倾的扇状或脊状地形，其形态呈锥形缓坡，该结构被称为“尾部（tail）”。 本图层源自Britice V2版本，该数据集自2004年起持续更新。针对不列颠与爱尔兰地区末次冰盖的地貌痕迹，学界已开展了百余年的研究。在此期间，科学家通过野外实地考察、卫星数据与航空摄影制图，生成了地貌（地形）图，记录了冰盖消退后遗留地形的分布情况。研究团队梳理了来自学术文献、英国地质调查局与爱尔兰地质调查局的制图资料在内的1800余篇文献。如需了解更多细节，请访问Britice官方网站：https://sheffield.ac.uk/geography-planning/research/geography/projects/britice