Willandra Lakes revisited: environmental framework for human occupation

Abstract

AbstractThe story of the Willandra Lakes is also the story of those ancient people who lived there. The landforms, sediments and soils provide the environmental framework within which the patterns of human occupation must be interpreted. The original stratigraphic system involved just two units, the Mungo and Zanci. Two additional units are now defined; one incorporating complexities between Mungo and Zanci, the Arumpo Unit, and a second to acknowledge the reality of a lake full phase near 18ka cal., postdating Zanci aridity of the last glacial maximum. This new unit is defined from Lake Mulurulu as the Mulurulu Unit.Improved facies analysis from data involving lake sediments, freshwater quartz beach sands (QBSs) and lake‐dry pelletal clay dunes (PCDs) helps refine the sequence of environmental changes. Revision of radiocarbon chronologies with conversion to calendar years, and additional dates (radiocarbon, luminescence, amino acid racemisation) permit new age definitions of major environmental changes and human‐land interactions.Following a lake‐full phase (Lower Mungo time) from before about 55ka cal., a phase of PCD accumulation is dated to near 40ka cal. defining an early stage of hydrologic stress. Progressive water level oscillations continued (Arumpo time) culminating in major drying with deflation and extension of regional dune building over large areas of the Murray Basin near 20ka cal. (Zanci time). Freshwater returned temporarily to the Willandra lakes about 18–19ka cal.Throughout the period 25–19ka cal. spanning the glacial maximum, the apparent absence of fish and unionid mussels may reflect major temperature depression corresponding also to the period of maximum aridity. The ecological stress experienced at this time had an immense impact on the landscape, plants and especially larger animals, requiring new adaptive responses from human occupants. Early grinding techniques, pre‐dating evidence of seed grinding, are suggested.Reconstruction of the sedimentary sequence at the main archaeological site at Joulni reveals a pre‐Mungo unit deep in the sequence of a system developed by barrier construction isolating the Joulni Plain from the main lake. Analogous conditions at Lake Victoria today mirror development of the Joulni archaeological site. Oldest artefacts occurring within this un‐named unit are dated beyond 45ka cal.Human occupation on the lakeshore barrier system at Lake Mungo involved aquatic harvesting (fish and shellfish) associated with human burials before the onset of PCD deposition, pre‐40ka‐cal. The association here of the complex burial ritual (Mungo III) involving anointing with ochre at this time presents one of the dramatic mysteries of ancient human cultural development. In death, the story of that person illuminates our understanding of those ancient occupants and the Ice Age environments that supported them.