environmental sciences research institute - University of Ulster

Geomorphological characteristics and significance of Late Quaternary paraglacial rock-slope
failures on Skiddaw Group terrain, Lake District, northwest England
Figure 2. Rock slope failure on Crag Fell, Lake District
Eight relict rock-slope failures have been investigated on Skiddaw Group terrain in the Lake District, northwest England.
Five of the failures are rockslides, one is a product of slope deformation, and two are compound features with evidence
for sliding and deformation in different sectors. Because none of the failures appear to have been overrun and modified
by glacier ice it is inferred that they all post-date the Last Glacial Maximum (c. 21,000 years Before Present). Slope stress
readjustments resulting from glacial and deglacial influences are considered to have weakened the slopes, and application
of the term paraglacial is appropriate. Permafrost aggradation and degradation, seismic activity and fluvial erosion are
among processes that may have contributed to failure at certain sites. The failures are significant as potential debris
sources during future ice advances, contributing to valley widening and cirque enlargement and, possibly, for acting as
sites of cirque initiation. Previously, Skiddaw Group rocks have been regarded as homogeneous and of limited resistance
to the weathering and erosion associated with Quaternary glacial, periglacial and fluvial processes. These characteristics
and processes have been used to explain the steep smooth slopes and rounded hills that dominate Skiddaw Group
terrain. Rock-slope failure has also helped shape this terrain and should be incorporated in future interpretations of
landscape development.
Peter Wilson
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