An actualistic taphonomic study exploring site formation in the submerged caves of Mount Gambier, South Australia

Abstract

Recent recovery of historic, non-human bone assemblages from two underwater karst caves in Mount Gambier, South Australia, have opened new avenues for understanding the deposition and early preservation of bone in these systems. To date, there have been limited taphonomic studies focusing on the depositional processes and burial environments of submerged caves, preventing a comprehensive understanding of site formation in these environments that flux between wet and dry conditions commonly linked to glacialinterglacial cycles. This work asks the question: can taphonomic analyses distinguish between animals deposited directly in wet cave environments versus those that experienced secondary submersion after decay, or cyclical submersion events? Taphonomy and early diagenesis of terrestrial underwater caves deposits are here studied through an observational, actualistic approach. Analysis of domesticates (e.g. cow, sheep) from Green Waterhole (collapsed doline) and Goulden’s Hole (sinkhole) provides an opportunity to investigate relatively recent taphonomic histories and associated changes to bone in the phreatic (wet) and vadose (dry) cave environments. These establish a benchmark and framework to assess archaeological and palaeontological deposits found in submerged caves. Using macroscopic (assemblage and surface), microscopic (histological), and radiometric (C14) approaches, this research provides a suite of bone modification signatures linked to phreatic environments in a chronological framework. Using a mixed method approach that investigates taphonomic patterns associated with groundwater, phreatic systems, and freshwater, our study provides baseline taphonomic data for other terrestrial and submerged sites in Australia and internationally. This study applies archaeological science to reconstruct environmental narratives of glacial and interglacial cycles directly from bone and fossil assemblages. © The Authors