Sediments and landforms in an upland glaciated-valley landsystem: upper Ennerdale, English Lake District

The genesis of moraines associated with British glaciers of Younger Dryas age has proved controversial in recent years. A number of alternative hypotheses exist and, whilst it is generally accepted that such features are polygenetic in origin, some workers have argued that not all of the proposed mechanisms are valid. This paper seeks to explore these issues, using a case study from the English Lake District. A landsystems approach is adopted, integrating information at a variety of spatial scales to explain the development of the sediment-landform associations in upper Ennerdale. The evidence suggests that landform development resulted from a combination of icemarginal deposition and englacial thrusting. It is probable that thrusting resulted from flow compression against a reverse bedrock slope, combined with the confluence of ice from two separate source areas. It is argued that, whilst englacial thrust moraines may not be commonly associated with British Younger Dryas glaciers, under certain conditions englacial thrusting is an important process in landform development

Structural glaciology of Austre Brøggerbreen, northwest Svalbard

<p>Structural glaciological maps can be used to study the structural evolution and past dynamics of glaciers. The map described here documents the glacier-wide structural characteristics of Austre Brøggerbreen, a <i>c</i>. 12 km² predominantly cold-based valley glacier in northwest Svalbard. The structural map reveals that the glacier is dominated by deep-penetrating fractures that are now relict (crevasse traces). These structures indicate that, despite being relatively inactive at present, the glacier was once much more dynamic, presumably during its last advance in the Neoglacial (<i>c</i>. 1900 AD). Contemporary glacier structures (i.e. those that are actively forming) include primary stratification, longitudinal foliation and rare surface fracturing (crevasses and water-healed crevasses). Relict fracture sets become increasingly re-orientated and folded down-glacier as a result of ductile flow. Individual flow units show large differences in the evolution of structures, indicating that the flow units have been subject to different flow histories and dynamics. The map will also be useful for future change-detection studies on this rapidly receding glacier.</p