Micromorphology and site formation at Die Kelders Cave I, South Africa

The deposits of Die Kelders I were previously described and studied by Tank ard & Schweitzer (1974, 1976) from the standpoint of classical granulometri c analysis of sand from a coastal cave in order to infer the geological his tory of the cave and its environs. This paper supplements these earlier wor ks by taking a more holistic approach toward site formation processes by in cluding investigation of the biogenic and anthropogenic influences on the c ave deposits and history. The study employs the technique of soil micromorp hology, which is the study of resin-impregnated, undisturbed blocks of sedi ment and petrographic thin sections, in which sediments from all areas of t he cave were examined. The study showed that diagenesis of the deposits in the eastern areas of the excavation resulted in decalcification, which in t urn brought about slumping and compaction. Equivalent stratigraphic layers exposed in the western and central areas were only mildly decalcified and c onsequently, these sediments contain limestone rock fall and relatively abu ndant marine and terrestrial mollusks, the: latter not dissimilar to the La te Stone Age (LSA) midden which covers these deposits. Thus, in spite of lo wered and more distant shorelines, marine resources were exploited during M iddle Stone Age (MSA) times. Observations from these calcareous units also clearly demonstrates that previously recognized "occupational horizons" (e. g. Layers 6, 8 and 10) can be resolved micromorphologically into several ep hemeral events, such as buming/ fire, redistribution of ashes by wind and w ater, and non-deposition; the latter is shown by phosphatic alteration of s ediments exposed on former surfaces and accumulation of guano, or the prese nce of millimeter-thick truncation surfaces below which aeolian dust infilt rated. Both field and microscopic observations illustrate that the deposits in caves are highly variable from wall to center, and that excavations sho uld not be localized in just one microenvironment of the cave site. (C) 200 0 Academic Press.