The geomorphology of the south-western and central Lake District, England is used to reconstruct the mountain palaeoglaciology pertaining to the Lateglacial and Younger Dryas. Limitations to previous ice-mass reconstructions and consequent palaeoclimatic inferences include: (i) the use of static (steady-state) glacier reconstructions, (ii) the assumption of a single-stage Younger Dryas advance, (iii) greatly varying ice-volume estimates, (iv) inexplicable spatial variations in ELA (Equilibrium Line Altitude), and (v) a lack of robust extent chronology. Here we present geomorphological mapping based on aerial photography and the NextMap Britain Digital Elevation Model, checked by ground survey. Former glacier extents were inferred and ELAs were calculated using the Balance Ratio method of Osmaston. Independently, a time-dependant 2-D ice-flow model was forced by a regional ELA history that was scaled to the GRIP record. This provided a dynamic reconstruction of a mountain ice field that allowed for non-steady-state glacier evolution. Fluctuations in climate during the Younger Dryas resulted in multiple glacial advance positions that show agreement with the location of mapped moraines, and may further explain some of the ELA variations found in previous local and static reconstructions. Modelling based on the GRIP record predicts three phases: an initial maximum extent, a middle minor advance or stillstand, and a pronounced but less extensive final advance. The comparisons find that the reconstructions derived from geomorphological evidence are effective representations of steady-state glacier geometries, but we do propose different extents for some glaciers and, in particular, a large former glacier in Upper Eskdale.

The glacial geomorphology of the south-west Lake District has been mapped over 98 km 2 using 1:10,000 aerial photography, Google Earth images and a high resolution digital elevation model (NEXTMap). The area is subdivided into two map sheets (eastern and western) and includes Upper Eskdale, the Langdales, the valleys surrounding Wastwater and the neighbouring valley of Ennerdale. The maps include 9 surficial geology units in addition to the various geomorphological features. Suites of arcuate moraine ridges record the sequential retreat of topographically-controlled glaciers. Flutings, which may relate to radial outflow of ice from the central fells during the Late Devensian, are also present. 'Paraglacially modified sediments and scree' is the largest of the map units, reflecting the extensive occurrence of ancient and present-day hillslope processes in the region. More recent palaeo-glaciological reconstructions of the Younger Dryas (12.7 -11.5 ka BP) ice extent in the Lake District remain spatially restricted, with many covering only small areas of the Lake District. Furthermore, these reconstructions suggest substantially different ice configurations. In particular, the south-west Lake District remains a key area of uncertainty. We use the geomorphological maps presented in this paper to produce new reconstructions of Younger Dryas ice extent in the south-west Lake District. We combine this with previously published reconstructions from across the whole Lake District to provide a complete regional Younger Dryas ice reconstruction.

This paper presents a new map of the glacial geomorphology of ∼ 800,000 km 2 of north-west Canada. The mapped area includes parts of Northwest Territories and Nunavut which were covered by the Laurentide Ice Sheet during the Late Wisconsinan glaciation. It has been hypothesized that ice streaming occurred here during this time and the area has also been identified as a potential drainage pathway of glacial Lake Agassiz. Mapping was carried out remotely using a range of spaceborne imagery with varying spatial resolutions, including Landsat ETM+, ASTER and SRTM. Aerial photography was also used in areas where cloud obscured the Landsat imagery. The map records 94,780 individual landforms including moraines, eskers, large meltwater channels and lineations. Highly elongate bedforms with convergent flow traces and abrupt lateral margins are abundant throughout the mapped area and most likely represent former zones of streaming flow. Numerous eskers can be traced for tens of kilometres and are found both parallel and sub-parallel to abundant lineations. Moraine ridges are also identified which mark Late Wisconsinan ice margin positions and a series of smaller ridges are also identified within areas of hummocky topography. The map is intended to form the basis of a regional ice sheet reconstruction from the Last Glacial Maximum through to deglaciation, which we suggest is likely to involve marked changes in the spatial and temporal activity of ice streams.

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