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Article Excerpt
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).
Vinnicombe obtained radiocarbon ages from a series of fifteen test pits and three auger-sampled sites from a range of different geomorphic zones across the Burrup Peninsula for Woodside Petroleum in 1980-81 (1987). Materials from seven of the test pits and one of the augered samples have been dated, providing radiocarbon ages of between 6740 [+ or -] 130BP and 260 [+ or -] BP. These ages are associated with a number of different site types including shell middens, open campsites, a stone arrangement site and a rockshelter. Harris (1988) analysed the material from the Georges Valley site, which has three radiocarbon ages ranging between 4190 [+ or -] 100BP and 1360 [+ or -] 130BP. She noted significant differences between the sequences at Skew Valley and Georges Valley, where rocky platform mollusc species dominate the sequence, with an increase of mangrove mollusc species such as Terebralia sp. combined with the mid-littoral sand and mudflat species Anadara granosa after c.2500BP. Unlike Skew Valley, no microliths were excavated from Georges Valley. This difference in sequences at the two sites is noteworthy, given they are only about 10 km apart.
Veth and O'Brien (1986: 57) commented on the apparent lack of stratified archaeological midden sites on the Abydos Plain, with the exception of the Burrup Peninsula. They suggested that this absence was due to erosional processes rather than cultural ones, pointing to the erosion and periodic flooding which occurs in the region. Since this article was published, a number of stratified midden sites have been located on the Abydos Plain, although as Clune notes (2002: 65), in relatively low densities. Bradshaw undertook a series of excavations in the period 1992-94 to attempt to establish a regional sequence for a section of the coastal Pilbara from the Maitland River to Balla Balla. Radiocarbon ages obtained for these excavations range from 8520 [+ or -] 80BP to 1470 [+ or -] 50BP (Bradshaw 1995). These sites were predominately composed of Anadara granosa, and appear to replicate the Skew Valley type sequence of a change from Terebralia spp. to Anadara granosa after approximately 4000 years BP.
The Terebralia-Anadara type sequence in north Western Australia
Excavations by Lorblanchet at Skew Valley and Gum Tree Valley on the Burrup Peninsula in 1975-6 and 1984 established the Holocene type sequence for the region. Lorblanchet found that the basal layer of the midden at Skew Valley was composed primarily of the gastropod Terebralia spp., while the upper layers were composed predominately of the bivalve Anadara granosa (1992:40). The change in shell species dated to approximately 4000 years BP and was associated with the appearance of microliths in the deposit. Lorblanchet, who noted an association between engraving sites and shell middens, and whose work was primarily concerned with establishing a typological sequence for the rock art, also obtained a date of 18,510 [+ or -] 260BP from a large Syrinx aruanus shell found in association with rock engravings. However, the association between the shell and stone artefacts found at the site is tenuous (Clune 2002:64).
The sequence of change from a dominance of the mangrove gastropod Terebralia spp. in archaeological sites dating to the early Holocene to a dominance of the sand and mudflat adapted bivalve Anadara granosa in the mid-Holocene documented at Skew Valley has subsequently been found to occur in a range of north Western Australian coastal sites, including Noala 1 and Haynes Cave on the Monte Bello Islands (Veth 1994, 1995), Clarke's Cave, Anadara Mound and Not-so-Secret Shelter on the Burrup Peninsula (Bradshaw 1995:37), near Port Hedland at FMGP04-014 (Harrison, this issue), in archaeological sites at Shark Bay (Bowdler 1990a, 1990b) and Cape Range (Morse 1993, 1999, Przywolnik 2005), south of Shark Bay at the Zuytdorp site (cited in Przywolnik 2005:187), at Tubridgi Well near Onslow (Veitch and Warren 1992), and in the southwest Kimberley at the rockshelter sites of Koolan Shelter 2 and Widgingarri Shelter 1 (O'Connor 1999a).
The earliest Terebralia spp. date on the north Western Australian coast currently comes from Cape Range at Jansz rockshelter on the southern Pilbara coast and is 10,730BP (Przywolnik 2005), suggesting that the mangrove environments conducive to the growth of the gastropod developed during the terminal Pleistocene. It is useful at this point to draw a distinction between the regional divisions of the Carnarvon Coast, running north from the Murchison River to the Ashburton River, the Pilbara coast, from the Ashburton to the De Grey River, the Canning Coast, from the De Grey to Roebuck Bay, and the Kimberley coast, extending from Roebuck Bay to the Ord River (see Figure 1 after O'Connor 1999b). While Terebralia occurs in sites dated to c. 10,000BP on the Carnarvon Coast, it first occurs in archaeological sites in the...
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