Coastal shell middens of the Abydos coastal plain, Western Australia.

Abstract

Middens and mounds dominated by Anadara granosa began to be formed on the Abydos Coastal Plain sometime between 4400 and 5300 calibrated years before present, and while mounds appear to have ceased forming some 1800-1600 years ago, middens continued to form until the early twentieth century or later. In some cases, the earliest of these middens and shell mounds formed on top of older middens from which Anadara granosa is totally absent, and in which Terebralia spp. (while occurring in relatively low concentrations) is the dominant shell species. Anadara granosa dominated middens (sensu lato) occur in a variety of forms across the landscape, including large shell mounds, earth mounds (or mounded shell middens), lenses of shell eroding out of well-developed dunes, and undifferentiated surface shell scatters. The large number of middens which occur throughout the region from the mid Holocene, and the volume of shell represented by these sites, point to the occurrence of significant economic and social changes from the mid to late Holocene. The Abydos Coastal Plain experienced increasing aridity, and, as a result, increased resource stress during the mid-Holocene. We suggest that the large, single species Anadara granosa middens were occupied during regular periods when large groups of Aboriginal people undertook ceremonial activities after the wet season, when resources were abundant. Changes apparent in the archaeological record, including the occurrence of large numbers of Anaclara granosa dominated middens and shell mounds, increased establishment of archaeological sites and increased complexity and distance of exchange systems, came about as a result of social, economic and logistical restructuring. This in turn was the result of the effects of resource stress on local Aboriginal people over the course of the mid to late Holocene.

Keywords: Archaeology, shell middens, Abydos Plain, Pilbara, Anadara granosa

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The mid-Holocene appearance of large, single species Anadara granosa shell middens and the shift from mudwhelk to bivalve-dominated assemblages in rockshelter and open site deposits in north Western Australia has been well documented, although details of the timing and meaning of such shifts have not yet been clarified. This paper draws on the results of excavations undertaken by the authors on the Abydos Plain in the northern Pilbara coast to clarify the timing of such shifts, and proposes that the appearance of such sites in the archaeological record results from a series of changes in economic scheduling, resource availability, social organisation and mobility. Our interpretation of these data suggests that the large, single species Anadara granosa middens were occupied during regular, annual periods when large groups of Aboriginal people lived in a semi-sedentary fashion immediately after the wet season, when resources were abundant and ceremonial activities were undertaken. This explanation has implications for the interpretation of single species bivalve dominated shell middens throughout north Western Australia.

Previous archaeological research in the coastal Pilbara

Pleistocene occupation of the north Western Australian coast was established by Morse (1993, 1999), whose excavations at Mandu Mandu Creek rockshelter in Cape Range National Park revealed an occupation sequence dating back some 30,000 years. The oldest dated archaeological sites on the Western Australian coast are presently Jansz and C99 rockshelters, located approximately 50 km north of Mandu Mandu Creek, with occupational sequences dating to 35,000BP and 34,000BP respectively (Przywolnik 2005). The oldest shell midden on the north Western Australian coast is presently Wooroora midden, which has been assigned a radiocarbon date of 7810 [+ or -] 110BP (Kendrick and Morse 1982).