Radiocarbon dates from three Kaiadilt Aboriginal sites on the South Wellesley Islands, southern Gulf of Carpentaria, demonstrate occupation dating to c.1600 years ago. These results are at odds with published linguistic models for colonisation of the South Wellesley archipelago suggesting initial occupation in the last 1000 years, but are consonant with archaeological evidence for post-4200 BP occupation of islands across northern Australia, particularly in the last 2000 years.
Keywords: radiocarbon dates, island colonisation, Kaiadilt people, Kayardild language, Bentinck Island, Sweers Island
The ten islands of the South Wellesley archipelago are dominated by Bentinck Island (c.150 kin2), the country of Kaiadilt people (Figure 1). These islands were created between 8000 and 6500 BP with rising sea-levels, peaking at +2 m around 5000-6000 years ago (Nakada and Lambeck 1989; Reeves et al. 2007), and comprise ancient weathered laterites and recent estuarine, beach and dune deposits. A minimum open water crossing of 10 km between Bessie and Horseshoe Islands is required to reach Bentinck from the mainland at Point Parker, with limited intervisibility between Bentinck and the mainland. The geographical isolation of Bentinck Island has been cited as a major factor in the development of the distinctive biology, language and material culture of Kaiadilt people (Curtain et al. 1972; Curtain et al. 1966; Evans 1995, 2005; Memmott et al. 2006; Memmott et al. 2008; Simmons et al. 1962, 1964; Tindale 1962a, 1962b, 1977, 1981; Trigger 1987; White 1997).
Limited archaeological studies have been conducted in the southern Gulf of Carpentaria. On the adjacent mainland Robins et al. (1998) have reported radiocarbon dates for three sites dating between c.1200 and 200 years ago. For Mornington Island in the north, Memmott et al. (2006:38, 39) report dates of c.5000-5500 BP from Wurdukanhan on the Sandalwood River on the central north coast of Mornington Island. In the Sir Edward Pellew Group 250 km to the northwest of the Wellesleys, Sim and Wallis (2008) have documented occupation on Vanderlin Island extending from c.8000 years ago to the present with a major hiatus in occupation between 6700 and 4200 BP linked to the abandonment of the island after its creation and subsequent reoccupation.
Tindale (1963) recognised the archaeological potential of the Wellesley Islands, undertaking the first excavation in the region at Nyinyilki on the southeast corner of Bentinck Island. A 3' x 7' (91 cm x 213 cm) pit was excavated into the crest of the high sandy ridge separating the beach from Nyinyilki Lake:
The first 20 cm had shells, a 'nara shell knife, turtle bone. At 20 cm there was a piece of red ochre of a type exactly parallel with the one which one of the women was using in the camp to dust her thigh in the preparation of rope for the raft the men are making for me. The 20-30 cm band was sterile reddish sand, wind blown, except for one piece of ironstone sharp on one margin which probably was man transported. Below that 80 cm was the same sterile reddish sand (Tindale 1963:243,245).
Tindale (1977:251) also attempted to link archaeological finds on Bentinck Island to palaeogeography, speculating on a mid-to-early Holocene antiquity of some deposits:
the finding of a crude bifacial stone tool of mariwa type
... known to the islands as ['tjila'nand], which was in situ
in deposits which had been planed during the mid-Recent
high sea levels between about 6000 and 3800 BP and
subsequently exposed by lateral gully erosion.
No other excavations have been conducted on the South Wellesley Islands and the chronology of the southern Gulf region as a whole remains poorly resolved. Current chronologies for occupation of the South Wellesley Islands are based on linguistic analyses. Wellesley Islanders, along with their mainland neighbours, all speak closely-related languages classified as part of the Tangkic family forming a geographically contiguous language unit derived from a common ancestral language (Evans 1990, 1995, 2005). …