Applications of Geological methodologies in archeological research have been rapidly increased around the world and developed as a new field known as Geo archaeology. The field Geo archaeology provides the knowledge and the skills to understand the site formation processes, human occupations and their activities. Particle size analysis, organic matter content and phosphate analysis of sediments are commonly used techniques in Geo archaeological studies. Sediments from an excavation carried out in Varana rock shelter no 5, which is a prehistoric site were analyzed by above mentioned Geo archeological methods to study stratigraphic of the sediment layers and prehistoric human occupation.

Varana rock shelter-no 5 is comparatively a small place found in cave complex at Varana temple premises, Sri Lanka. The rock shelter is made up of a granitoid boulder rest on the exposed outcrop of Ambagaspitiya granitoid body. Sediment deposit accumulated under the rock shelter is Autochthonus derived by detaching of rock fragments, mineral fragments and individuals grains from walls and roof of rock shelter. Particle size analysis and textural studies show that the sediments are clastic and coarse grained in texture. Dominant minerals of the clasts are quartz followed by feldspar.  According to the values of effective grain size, average grain size and cumulative coefficient, three litho stratigraphic units representing different environmental conditions can be identified. Top historic layer and bottom prehistoric layer contain finer fraction than that of middle post Mesolithic layer. Both Phosphates content (P_tot) and organic matter content of sediments are decreased downward. Though the P_tot is low, the positive correlation of P_tot with organic matter content and the densities of lithic tools and pottery assemblages indicate rate of human activities and the anthropogenic alterations of soil geochemistry. The lack of evidences of prehistoric hearths and low concentrations of P_tot may gives an idea that rock shelter had been used as an occasional temporary place during the prehistoric period.

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Pathmakumara Jayasingha¹, Raj Bandara², Gamini Adikari³, Arjuna Mahathanthila³

1. Research Laboratory, Central Cultural Fund, Sri Lanka

2. Department of Archeology, Sri Lanka

3. Postgraduate Institute of Archaeology, University of Kelaniya, Sri Lanka

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Tags: Excavation, Field Archaeology, Geo Archaeology, Varana Cave
Posted in Articles, Field Archaeology