Prehistory Down Under: Archaeological Investigations of Submerged Aboriginal Sites at Lake Jasper, Western Australia
Dortch, Charles, Antiquity
Much of Australian prehistory lies under water. Although confined to the continent's extreme southwestern corner, field studies described in this report show that this submerged prehistoric component is very real, with numerous archaeological sites and former land surfaces awaiting investigation on the floors of Australia's lakes, rivers and estuaries, and on its submerged continental margins.
Since 1989 I have directed Western Australian Museum and volunteer divers investigating prehistoric sites on the floors of fresh-water lakes and estuaries in the extreme southwest of Western Australia. These underwater and related investigations, which have produced new kinds of archaeological evidence in settings largely ignored or given only cursory attention, complement the growing number of archaeological studies investigating Aboriginal subsistence and occupation patterns in this part of Western Australia dating back to the Late Pleistocene (Anderson 1984; Balme et al. 1978; Baynes et al. 1975; Bird 1985; Dix & Meagher 1976; Dortch 1979; 1984; 1991; in press; Dortch & Gardner 1976; Dortch & Hesp 1993; Dortch & Morse 1984; Dortch et al. 1984; Dortch 1994; Ferguson 1981; 1985; Hallam 1979; 1987; 1989; Lilley 1993; O'Connor et al. 1993; Pearce 1978; 1982; Pearce & Barbetti 1981; Schwede 1990; Smith 1982; 1993).
In southwestern Australia, first-hand accounts compiled mainly by early to mid 19th-century British colonists give direct insight into the traditional land-use patterns and subsistence activities of the Nyungar-speaking Aboriginal hunter-gatherer population. These ethnohistoric documents are invaluable sources of inference in the assessment of economic and other aspects of the prehistoric coastal occupation under investigation. Of particular relevance here is the information they provide about wetland/lacustrine subsistence, which ranks with fire drives for game, estuarine fishing and rhizome and tuber gathering as one of the key economic activities of the Nyungar population (Hallam 1975; 1989; Meagher 1974; Meagher & Ride 1979).
The Lake Jasper underwater site complex described in this paper is seen as only one component within a regional pattern of occupation and subsistence. Judging by the environmental diversity of this part of the Southern Ocean coast, and by what may be inferred from the regional ethnohistoric record, from Nyungar traditional knowledge and from archaeological site locations, southwestern hunter-gatherer economy was based on the exploitation of food and other resources from 'contiguous environmental zones' (Anderson 1984: 1); in the coastal area under study these are estuaries, inshore marine waters, lakes, wetlands and a wide variety of terrestrial habitats.
The Lake Jasper investigations
Lake Jasper is situated in a swampy corridor of coastal sandplain (elevation 20-40 m a.s.l.) between a low plateau (40-60 m a.s.l.) to the north, and, on its seaward side, an aeolian calcarenite ridge (150-195 m a.s.l.; [ILLUSTRATION FOR FIGURE 1 OMITTED]). Present at depths to 10 m on the 4 sq. km freshwater lake's floor [ILLUSTRATION FOR FIGURE 2 OMITTED] are extensive scatters of flaked stone artefacts, and in their growth positions numerous stumps of trees and grass trees (Xanthorrhoea sp.). I first identified several of the Lake Jasper prehistoric stone artefact scatters (sites 1-3: [ILLUSTRATION FOR FIGURE 2 OMITTED]) after severe 1988 drought conditions had lowered the lake's level, revealing artefact scatters and tree stumps on exposed parts of its floor, and in shallows less than 1 m deep. The following year a Western Australian Maritime Museum team of underwater archaeologists joined me for detailed recording of sites 2 and 3 in the lake's inshore waters (Dortch et al. 1990). In 1990 a mainly volunteer diving team recorded site 5 located on a shoal in the lake centre, and sites 8 and 9 in some of the lake's deeper parts (9-10 m), showing for the first time that most of the lake floor is a former land surface (Dortch & Godfrey 1990). …