Small Scale Glacial Erosion Forms and their Possible Relation to Post-Glacial Weathering

ABSTRACT

The paper describes several types of small scale forms on the stoss side of a roche moutonnée surface, recently exposed in a gravel pit in the Fjärås bräcka complex, SW Sweden. The forms were filled with weathered rock debris. When excavated, they showed a striking resemblance to forms generally accepted to be shaped by glacial/glaciofluvial erosion. In addition to these forms there were irregular cavities for instance smoothly rounded throughs and irregular rough surfaces resembling those claimed to be preglacial weathering forms. In spite of the few observations made, many small scale glacial erosion forms are likely to be the result of a three-step process i.e. glacial pressure deformation of the bedrock, subsequent weathering of the deformed rock, and finally excavation of the deformed rock by exogenic processes. Further on it seems probable that many rough surfaces of the type described in the paper are the result of glacial pressure deformation and subsequent weathering.