Murtoos are recently discovered triangular-shaped subglacial landforms that form under warm-based ice and in association with significant subglacial meltwater flow. They appear in distinct fields and commonly occur in the area that was covered by the Fennoscandian Ice Sheet during glacial periods. Murtoos potentially represent a transition form from non-channelized to channelized subglacial drainage networks. In the present study, we analyse and classify murtoos and murtoo-related landforms in the Finnish area of the Fennoscandian Ice Sheet based on their characteristics and appearance in LiDAR-based digital elevations models. Combined with morphometric analyses, the observations suggest that five types of murtoos and murtoo-related landforms are common and widespread in Finland: (i) triangle-type murtoos (TTMs), (ii) chevron-type murtoos (CTMs), (iii) lobate-type murtoos (LTMs), (iv) murtoo-related ridges and escarpments (MREs), and (v) other murtoo-related polymorphous landforms (PMRs) that look like small mounds and ridges. The morphometric characteristics of the different types are described here in detail, and it is shown that they are spatially and geomorphologically related. In addition, we provide examples of murtoos other than the TTMs to demonstrate that different murtoo types and murtoo-related landforms are composed of similar sediments and architectural characteristics. The diversity of murtoo landforms and the transition between distinct murtoo types indicate rapid and complicated variations in the configuration of subglacial hydrology at different spatial and temporal scales. This study emphasizes the essential role of subglacial meltwater in the shaping of glacial landscapes and the redistribution of large volumes of sediments during the deglaciation of the Fennoscandian Ice Sheet.

中文翻译：

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Fennoscandian 冰盖芬兰地区 murtoos 和 murtoo 相关冰下地貌的多样性

Murtoos 是最近发现的三角形冰下地貌，形成于暖基冰下，并与重要的冰下融水流有关。它们出现在不同的领域，通常出现在冰川时期被芬诺斯坎德冰盖覆盖的区域。Murtoos 可能代表了从非渠道化到渠道化冰下排水网络的过渡形式。在本研究中，我们根据基于 LiDAR 的数字高程模型中的特征和外观，对芬诺斯坎迪亚冰盖芬兰地区的 murtoos 和 murtoo 相关地貌进行分析和分类。结合形态测量分析，观察结果表明五种类型的 murtoos 和 murtoo 相关地貌在芬兰很常见和普遍：(i) 三角型 murtoos (TTMs)，(ii) V 形 murtoos (CTMs)，(iii) 叶状 murtoos (LTM)，(iv) murtoo 相关的山脊和悬崖 (MRE)，以及 (v) 其他看起来像小土丘和山脊的 murtoo 相关多形地貌 (PMR)。这里详细描述了不同类型的形态特征，表明它们在空间和地貌上是相关的。此外，我们提供了除 TTM 之外的 murtoo 示例，以证明不同的 murtoo 类型和与 murtoo 相关的地貌由相似的沉积物和建筑特征组成。莫尔图地貌的多样性和不同莫尔图类型之间的转换表明不同时空尺度下冰下水文构型的快速而复杂的变化。