Soil-sediment-configurations on slopes of Central and Western Crete (Greece) and their implications for late Holocene morphodynamics and pedogenesis – A conceptual approach

Abstract

Geomorphological processes and soil formation in slope positions within the Mediterranean area have been in the focus of research for a long time. Many of the surface-near soil-sediment-configurations in the Mediterranean area have been termed soils and have been interpreted as typical (zonal) Mediterranean reddish-brown soils (RMS) of Terra Rossa type associated with clay illuviation as main pedological process. However, there has been an extensive scientific debate which (late) Holocene geomorphological and pedological processes in fact dominate current soil-sediment-configurations, especially before the background of a long-lasting history of intense human land use impacts.In the present study, we present field evidence as well as analytical data for a number of representative soil-sediment-profiles located in a variety of geological, geomorphological and climatic settings in central and western Crete (Greece). We have grouped the profiles in three schematic geomorphological categories in order to provide a geomorphological instead of a pedological context for their interpretation and comparison. Based on geochemical, mineralogical, geophysical and micromorphological evidence we could show that in most of the studied profiles, (late) Holocene pedogenesis is comparatively weak, except for bioturbation in combination with surprisingly high TOC-contents. Discontinuities within profiles are the result of geomorphological processes and the corresponding deposition of clearly distinguishable parent materials (substrates) rather than pedologic processes resulting in the in-situ differentiation of soil horizons. Furthermore, characteristic and ubiquitous peaks in grain size distribution within the clay and silt grain size fractions could be identified and are most likely related to long-range dust inputs. Whether the weak degree of recent pedogenesis is due to the long-lasting history of intense land use or rather due to the (naturally) high intensity of geomorphological processes and sediment relocation remains one of the main open questions raised by the results of this study.