SOIL & SEDIMENT MINERALOGY OF THE POKROVNIK SITE, DALMATIA, CROATIA: EVIDENCE FROM XRD ANALYSIS

High-resolution mineralogical characterization of the Pokrovnik site confirms the fertile soils of this Early-Middle Neolithic settlement formed from foreign volcanic material rather than local carbonate bedrock. The Pokrovnik site is under continuing investigation by the Early Farming in Dalmatia Project, an interdisciplinary effort toward understanding the origins of European agriculture. Previous geoarchaeological work at this site and the Middle Neolithic Danilo Bitinj site suggests the site landforms were blanketed with foreign volcanic material. In this well-developed karst landscape, soils formed from such ejecta would be deeper, better developed, and more fertile than the terres roses and rendzinas typical of the region.

X-ray diffraction analysis of soil profiles from four on-site archaeological excavation trenches and nine off-site locales clearly supports this theory. The on-site soils show an overall relative increase in felsic silicate content and decrease in carbonate content with depth. Within a 2m-deep site profile, calcite is conspicuously absent from two separate, distinct deposits composed of quartz, feldspar, muscovite, and montmorillonite. These deposits most likely represent the site soil parent, although they have been altered since deposition by pedogenic processes. We hope that further investigation of these materials will reveal more specifically the nature of these deposits and, thereby the source of the soils' long use-life. In contrast the off-site soils, which surround the site within the valley bottom, show increasing relative calcite content with depth, as would be expected of a soil with a carbonate bedrock parent.

We also plan to characterize carbonate soil clasts and bedrock samples from these on- and off-site profiles. Such analyses will inform the relationship between clasts found within the soil and the underlying bedrock, as well as the chemical interaction between both classes of rock and the soil fine fraction. Understanding these relationships at Pokrovnik will further both our understanding of Danilo Bitinj site soils and our evaluation of the possibility of the co-location of Neolithic settlement and volcanic ejecta deposits in Central Dalmatia.