Mature intermediate-scale surface karst landforms in NW England and their relations to glacial erosion

Landform-derived limestone surface lowering rates in Northern England have been reassessed from conventional rates of 50 cm of surface lowering in 15 ka; rates of 5 to 15 cm in 15 ka are seen as more sensible. These revised, lower, rates allow clearer understanding of surface landforms in these and other British limestone areas. It has been thought that larger karst landforms, e.g. larger surface closed depressions of 20 m+ plan scale, are considerably older than the Late Devensian, possibly with pre-Quaternary aspects However, it is hard to demonstrate the same for smaller landforms, of the scale of c 1-3 m, as the conventional rates of solution supported their formation since the Devensian. The lower rates of solution, applicable to dry interfluve areas, allow these intermediate-sized karst landforms to contain survival components, and to be considerably older than post-Devensian. This paper examines sites with these mature karst landforms, and considers their common characteristics and influencing factors, including their relationship to ice scour patterns. The sites range from near sea-level to above 400 m altitude