The glacier–rock glacier mountain landsystem: an example from North Iceland

A valley floor rock glacier in Nautárdalur, eastern Tröllaskagi, northern Iceland, has been investigated since the 1970s. Adjacent valleys are also examined as mountain landsystems. The methodology identifies ‘landform elements’ (features evident on slopes) on transects that can be identified and mapped from Google Earth imagery. Transects can be compared to show similarities and differences between slopes and valleys and can be used to trace debris and ice/snow flow paths within landsystems. The paper confirms that a glacier ice core is present throughout the Nautárdalur rock glacier. Traces of glacier activity can be found in some neighbouring small valleys but where rock glaciers are not present. Previous field observations, when coupled to current Google Earth imagery, indicate glacier ice formation and deformation over the past 200 years. The quantities and timing of weathered debris from headwall cliffs were sufficient to partly cover small glaciers, thus forming rock glaciers in some, but not all, valleys. The landsystem and transect approach thus indicate glacier origins for the rock glaciers identified. No evidence for ‘permafrost creep’ in scree slopes that might produce valley-side rock glaciers has been found.冰岛北部特罗拉斯卡吉（Tröllaskagi）东部的瑙塔尔达卢尔（Nautárdalur）谷底岩石冰川自20世纪70年代起便已被纳入研究范畴。毗邻山谷亦以山地地貌系统为研究对象开展了考察。本研究方法通过谷歌地球（Google Earth）影像识别并绘制样带上的"地貌要素"（即坡面上可见的地貌特征）。可通过对比样带，揭示坡面与山谷间的异同，并追踪地貌系统内碎屑与冰/雪的运移路径。本研究证实，瑙塔尔达卢尔岩石冰川全域均存在冰川冰芯。部分未发育岩石冰川的邻近小型山谷中，仍可找到冰川活动痕迹。结合既往野外观测与当前谷歌地球影像，可推断出过去200年间冰川冰的形成与变形过程。源头崖壁风化碎屑的产出量与产出时机，足以部分覆盖小型冰川，进而在部分（而非全部）山谷中形成岩石冰川。综上，地貌系统与样带分析方法证明，本次识别的岩石冰川均起源于冰川作用。未在可能形成谷侧岩石冰川的碎石坡中发现"多年冻土蠕变"相关证据。