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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >The topography of drumlins; assessing their long profile shape
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The topography of drumlins; assessing their long profile shape

机译：Drumlins的地形; 评估他们的长型形状

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The literature on drumlins is pervaded by the notion that their longitudinal profile is usually highly asymmetric with a stoss steeper end and a lee gentler end, and that this can be used to infer the palaeo ice flow direction. The idea is built up in many papers covering more than a century of research. However, most of the early published papers were qualitative in nature and more recent quantitative papers appear to challenge the ubiquity of the classical stoss-lee shape. Here the shape of the drumlin longitudinal profile of 29,238 drumlins in the British Isles has been analysed. Drumlins were grouped into flowsets for which a palaeo ice flow direction was inferred independently of the drumlin shape. Given such ice flow directions it was then possible to identify the upflow and downflow ends of each drumlin and to trace and extract its longitudinal profile. Results indicate that the highest point of the drumlin is usually found around half way along the profile. The mean slope angles at the stoss and lee ends were found to be very similar. Finally, the average profile built from all mapped drumlins appears almost symmetric. In conclusion, drumlin longitudinal profile is far from being the classically asymmetric shape widely reported in text-book descriptions. Drumlins are mostly symmetrical in shape with a very slight tendency towards the classical shape. Highly asymmetric drumlins do exist but are rare and with an almost equal numbers of drumlins that are the reverse of this. These findings are verified both at the entire population level and the flowset level. This demonstrates that the idealized stoss-lee shape of classically-asymmetric drumlins is not representative of the population and should be replaced with that of mostly symmetric bumps. Drumlin shape is not a good indicator of the palaeo ice flow direction.
机译：巧克力线上的文献被纵向轮廓通常具有高度不对称的洞穴，倾斜陡峭的末端和李温叶末端，并且这可以用于推断古冰流动方向。这个想法是在许多论文中建立的，涵盖了一个多世纪的研究。然而，大多数早期公布的论文都在自然界的性质中，最近的数量纸张似乎挑战了古典肥料形状的无处不在。在这里，已经分析了英国岛中29,238号牛头簇的滚动纵向轮廓的形状。 Drumlins被分组成散流，其可以独立于鼓形形状推断出古冰流方向。考虑到这种冰流方向，然后可以识别每个滚筒的上流和下流端并追踪并提取其纵向轮廓。结果表明，沿着轮廓的一半左右发现了鼓风的最高点。发现猪蹄和李端的平均斜角非常相似。最后，从所有映射的Dramlins建造的平均概要概况几乎看起来对称。总之，鼓形纵向轮廓远非是在文本书描述中广泛报道的经典的不对称形状。 Drumlins主要是对称的形状，朝向古典形状的倾向非常轻微。高度不对称的巧克力巧克力确实存在，但是罕见的，并且具有几乎相同的巧克力刀片，这是反向的。这些发现在整个人口级别和势力级别都验证。这表明经典非对称剑铃的理想化的猪蹄形状不是群体的代表，并且应该被大多数对称凸块所取代。 Drumlin Shape不是Palaeo冰流动方向的良好指标。

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