Implications of Soils in Archaeological Contexts along the Mediterranean Coast, Israel for Paleoenvironments and Basic Pedology.
Alexander Tsatskin, Zinman Institute of Archaeology University of Haifa, Mount Carmel, Haifa, 31905, Israel
The initial pedological studies in the Israeli coastal plain (Dan et al., 1968/1969) established that 1) red loamy hamra soils (Rhodoxeralfs) are associated with clayey swell/shrink grumusols (Vertisols) within catenas, and 2) the structure and evolution of catena are defined by a geomorphic pattern and the age of bedrocks. Rhodoxeralf/Vertisol catenas normally form on older surfaces, including Pleistocene lithified coastal dune ridges (kurkar), and sporadically contain Palaeolithic artifacts (Ronen 1977). In sandy dune fields Holocene regosols with Neolithic artifacts through Early Islamic sherds are found. Recent studies focus on instrumental dating, primarily IRTL and OSTL on feldspars and quartz sand, that places near-surface hamra/kurkar sequences in the time interval of ca. 100 ky and more. Refined absolute geochronology techniques are indispensable in local chrono-stratigraphic models, however the amount of controversies is still significant to enable unequivocal comparison with a global Pleistocene pattern. It is argued that integrated and updated soil studies in the archaeologically related sites are of primary significance for both paleoenvironmental reconstructions and pedologic theory. New studies have shown that the diversity of Rhodoxeralf/Vertisol catenas in terms of polygenesis and chronology is stronger than previously thought. For example, observations around the Epipalaeolithic sites (ca. 17-20 ky ago) at the outlet of Hadera stream showed that paleosols are basically cumulative/compound and include several soils probably formed on different substrates. However, the differentiation of separate pedological phases is basically obscured. These complex soils contain artifacts from Mousterian through Neolithic. Within and around archaeological sites soils also vary according to different degrees of paleohuman impact. The orientation of artifacts is not necessarily horizontal indicating their later displacement in the course of both bioturbation processes and more complex pedogeomorphic processes of restructuring, characteristic for Vertisols. Micromorphology, SEM/EDS and magnetic studies (low- and high-frequency low-field magnetic susceptibility, high field susceptibility, remanent magnetization etc) allow us to detail the morphological observations. Generally, Rhodoxeralfs are magnetically enhanced if rich in clay fraction, while Vertisols albeit more clayey, show lower values of magnetic properties. In many cases Vertisols overlie Rhodoxeralfs rendering a characteristic curve of magnetic properties. The identification of nano-sized magnetite, maghemite, hematite and goethite, proves their pedogenic accumulation irrespective to the mode of dust additions at the time of soil functioning, and probably genetic association with Fe-smectites. Complex micromorphological fabrics (Stoops, 1994) suggest juxtaposition of individual diagnostic features. Although clay coatings, Fe/Mn and calcitic pedofeatures are basically recognizable, albeit showing the evidence of aging and change, the very fact of their occasional juxtaposition calls for a careful interpretation. It is suggested that detailed studies of soils/paleosols in archaeological contexts not only shed light on on-site history in regard with environmental change and human activity, but contribute also to our understanding of modern soil transformations under accelerated man-induced impact. In this sense, the concept of metapedogenesis (Yaalon and Yaron 1966) seems applicable also to archaeologically related soils and paleosols and includes the following implications: ·More realistic evaluation of response times of relevant for modern practices soil attributes on the basis of the datasets from archaeologically related site. ·Assessment of technogenic impacts on the basis of enhanced magnetic susceptibility needs to take into account its high pristine values in terra-rossa and hamra. ·Refinement of regional archaeo-paleopedology via process-oriented approach and site classification in regard with paleosurface accretion and/or denudation. ·Execution of reciprocal soil/archaeological control over geochronological dating. KEYWORDS: archaeology, soil micromorphology, Mediterranean, metapedogenesis