ON THE PRESENTATION OF LAYERING IN PERIGLACIAL SLOPE DEPOSITS

Methods are discussed that appear suitable for more precisely subdividing periglacial slope deposits and their material composition beyond the level of field observation. The study area is the Bavarian Forest region and its surroundings in eastern Bavaria. As a first step significant information concerning layer changes and material characteristics is derived from grain-size distribution. For methodological reasons a further mathematical abstraction in the sense of layering coefficients is not feasible, however. Heavy mineral spectra allow the distinction of layers with eolian influence from the loess-free layers and point out material relationships. In addition they characterize the degree of weathering of both the periglacial deposits and the underlying bedrock. The Laacher See tephra as a means of dating is unfortunately absent in the study area. Principal and trace elements of the fine soil fraction are sensitive indicators of material change. The study of pedogenic oxides of various fractions reveal that the substrate of the periglacial slope deposits is composed of material modified by soil-forming processes prior to sedimentation. This is especially true for the middle layer, the analysis and origin of which stand at the center of this contribution. X-ray diffraction analysis of the clay fraction helps differentiate pedogenic transformations and sedimentary characteristics. It equally supplies evidence of considerable eolian influx of clay and silt in the main and the middle layer. The diagnostic characteristics of the individual layers are presented; peculiarities of the middle layer as well as divergencies from the criteria found in the literature are discussed.