Mapping practice

The basic mapping that is typically available as input for work at the ice-sheet scale comprises information at different levels of resolution. Eskers are generally marked on maps as individual landforms, whereas glacial lineations usually are marked in a generalized way emphasizing the orientation, to a lesser extent density, and only rarely the size of individual glacial lineations. Marginal moraines are likewise generalized, with discontinuous moraine belts or closely spaced ridges aggregated to generalized map symbols. Marginal meltwater channels represent a special problem, in that they are often of small size and occur in complex systems. Hence, they are often not represented on small-scale or overview maps. A proper analysis of deglaciation pattern based on channels will also require a detailed topographic rendition or digital terrain model to provide the necessary topographic context. The same holds true for glacial-lake shorelines in topographically complex terrain (Jansson, 2003). In reality, ice-sheet-scale inversion projects will to some extent rely on diverse mapping, with inherent differences in classification and cartographical principles. Any realistic inversion model will have to embrace a varying standard of map input and such differences have to be identified, carried through and compensated for in the entire reconstruction procedure.

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