Rock surface micro−roughness, Schmidt hammer rebound and weathering rind thickness within LIA Skálafellsjökull foreland, SE Iceland

Abstract

Abstract : Glacially abraded basaltic rock surfaces found within a Little Ice Age (LIA) fore− land of Skálafellsjökull (SE Iceland) were studied at eight sites of different age applying different weathering indices. They include surface micro−roughness parameters measured with the Handysurf E35−B electronic profilometer - a new tool in geomorphology, Schmidt hammer rebound (R−values) and weathering rind thickness. Values of these indices obtained from study sites exposed to subaerial weathering for more than ca. 80 years are significantly different than those from younger moraines closer to the glacier snout. Despite a wide scatter of readings within each study site, there is a significant correlation between the ages and the values of the indices. It is concluded that the micro−roughness parameters provided by the Handysurf E35−B profilometer, Schmidt hammer R−values and weathering rind thickness are robust indices of rock surface deterioration rate in short time−scales. There is mounting evidence that rock surface undergoes relatively rapid weathering during first decades since deglaciation.