Geomorphological mapping of glacial landforms from remotely sensed data: An evaluation of the principal data sources and an assessment of their quality

This paper presents the results of an experiment to compare glacial geomorphology mapped from remotely sensed imagery with 1 : 10,000-scale field mapping. The field mapping was validated against high resolution LiDAR imagery of an area glacierized during the Younger Dryas and found to provide an essentially reliable, if not complete, representation of the glacial geomorphology. The experiment consists of comparing the field mapping with digital elevation models (Shuttle Radar Topography Mission C-Band, Landmap, OS Panorama®, OS Profile®, NEXTMap) and satellite imagery (Landsat Thematic Mapper) of a 100-km2 region of central Scotland, north of Glasgow, that was last glaciated during the Last Glacial Maximum and during the Younger Dryas, respectively c. 14.5 and 11.5 cal. ka BP. For the purposes of this exercise, we concentrated on glacial lineaments (flutes, drumlins, and crag and tail), but attention was also given to moraine ridges and eskers. Qualitative and quantitative comparisons are performed and the results show that of the remotely sensed data sets, only NEXTMap Great Britain™ provided results that showed any approximation to the field mapping. OS Panorama® and OS Profile® provided very poor approximations, and the other methods fail to provide any information of value. Attention is given to the issues of scale and the differences between a small-scale detailed study, such as this experiment, in which a high resolution glacial geomorphological reconstruction is required, and the small-scale studies where the remote sensing techniques used here provide important evidence of regional significance when glaciers formed the largest elements of the landscape. The paper concludes with a consideration of protocols for future geomorphological mapping exercises, and outlines some of the requirements that must be adopted as these protocols are developed.