Willandra Lakes revisited: environmental framework for human occupation

Abstract

The 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 l8ka 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 l8-l9ka cal.Throughout the period 25-l9ka 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-40kaSchool of Earth Sciences, University of Melbourne, Parkville 3052. bowler@earthsci.unimelb.edu.au 120 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.

Dating the First Australians

“…While there is no doubt that some Lower Mungo sediments deeper than the burial are 60 ka, this is a maximum possible age and places no limit on how much later the burial pit was actually dug into the lunette. Similar remarks apply to the U/Th results on WLH-52 in Table 3, where there is no environmental information available and the apparent age corresponds to deposits underlying the Lower Mungo: the Golgol Unit (96-126 ka) in which no cultural material has been found (Bowler 1998;Bowler and Price 1998). The considerable uncertainty about the true age of all the Willandra skeletons suggest that none of the dates should be accepted at face value.…”

“…Large-scale archaeological excavations were carried out in the early 1970s near the south end of the Mungo lunette, penetrating more than 2 meters to sterile sands (Mulvaney 1974;Shawcross and Kaye 1980;Shawcross 1998). 14 C and TL dating results from the Willandra lakes have been recently reviewed (Bowler 1998;Bowler and Price 1998;Gillespie 1998). TL dating of heated sediments from under, and heat retainers within, hearths in the Mungo lunette overlap with calibrated 14 C dates on charcoal from the same fireplaces in the range 34 ± 3 ka (Barbetti and Polach 1973;Huxtable and Aitken 1977;Bell 1991).…”

Wind v water: Glacial maximum records from the Willandra Lakes

“…Study of the Willandra basins (Figures 1 and 2) involves reconstruction of their environmental history and its relationship to controlling climatic change. The various methods for data interpretation and hydrologic reconstruction have been discussed elsewhere (Bowler 1971(Bowler , 1998. In early evaluation, the history of the Willandra Lakes was summarised in terms of three major stratigraphic units, each related to a major cycle of hydrologic change.…”

“…The Zanci drying phase was directly related to the Last Glacial Maximum (LGM), the period of maximum ice extent in the Northern Hemisphere (Clark et al 2009), glacial ice on Kosciuszko (Barrows et al 2001) and lowest sea level (Lambeck and Chappell 2001). In later revisions, Bowler (1998) defined an Arumpo unit between Mungo and Zanci, and a final Mulurulu unit to account for evidence of late-stage filling especially in Lake Mulurulu. Coincident with the LGM (ca.…”

“…Questions of age, although of great importance, frequently remain difficult to assess because age estimates are constrained by limitations resulting from difficulties in field settings, and analytical constraints often with inevitably large errors (Bowler et al 1970;Gillespie 1997;Bowler 1998). The application of radiocarbon dating to organic carbon remains frequently failed to provide consistent and reliable results, whereas dating freshwater mussel-shell carbonate proved much more reliable (Bowler 1998;Gillespie 1998).…”