Determining rock surface micro-roughness and search for new method of relative dating of glacial landforms : a case study from Fláajökull (SE Iceland) and Biferten glacier (Swiss Alps) forefields

Micro-roughness was recorded on glacially abraded stones deposited since Little Ice Age by two glaciers: Fláajökull in SE Iceland (basalts) and Biferten glacier in Swiss Alps (limestones) in order to find indices of relative age of the glacial landforms. Micro-roughness of rock surfaces was analysed with use of Handysurf E35-B electronic profilometer which calculates following roughness parameters: Rz, Rzmax, Ra and Rsm. An increase in roughness parameters towards older moraines is observed in both forefields, however the change is more significant on limestone surfaces. Time-dependent surface deterioration is visible only within first decades of weathering of both types of rock, and further weathering does not cause increase in micro-roughness.