Australia: The Land Where Time Began

A biography of the Australian continent 

Juunkan-2

This is a large cavernous Rockshelter 50 m west of Juunkan-1. At this site there are 2 chambers that face to the south; a large western chamber that has very deep sediment and a roof that is at a cathedral-like height, and an eastern chamber that is lesser, smaller and largely not protected and with a floor of bare rock. The main chamber is 10 m wide and 10 m deep and its height at the dripline is 8 m. In the main chamber there are 3 general areas; in the western side, a scoured, rocky area there some plants where a hole in the roof has allowed some rain to enter, a main central area in which a large roof fall has resulted in the accumulation of extensive sediment, and at the eastern rear of the site, a raised area where bedrock is higher than in other areas, and where sediment accumulation is at its least.

A single 1 x 1 m test pit was excavated in 2008, as in the case of Juunkan-1. There were a total of 21, 5 cm spits excavated that concluded at about 1.05 m beneath the surface, where further excavation was prevented by large amounts of roof fall. Within the deposit were 5 stratigraphic units, which were largely related to changes in the weathering and minerals of the ironstone. There were 5 hearths recovered, and flaked stone at high frequency and animal bones were also recovered.

Dates of 470 ± 40 BP were determined for spits 2, 12 and 17 (Beta-247330) (540-490 cal. yr. BP), 16,160 ± 80 BP (Beta-247331) (19,490-19,080 ca. yr. BP) and 20,090 ±100 BP (Beta-247332). AMS techniques were used to obtain the lowest date of 20,090 BP and are derived from a depth of 85 cm beneath the surface. Neither the level of the lowest artefact nor a basal date for the site is represented by this date for the site. Slack et al. suggest the deposit at Juunkan-2 could be up to 0.5 m deeper than the excavations.

At this site 272 flaked stone artefacts were recovered from the test pit excavation. Spit 16 of the excavation was the only spit in which there were no artefacts, with spit 18 (at 90 cm depth) being the lowest recorded age determination of 20,090 BP. Unmodified flakes (95.2 %) dominate the assemblage, with a few flakes (4.4 %) and even few cores (0.4 %). The main raw materials used for the retouched artefacts are chert (n = 8), ironstone (n = 4).

The flaked stone assemblage was discarded at a low rate, though the rate remained steady throughout the occupation period, and then at spit 4, about 5,000 BP the discard rate increased fourfold. There doesn’t appear to have been a hiatus in occupation or sedimentation at the site before, during or after the LGM, though it is limited by the sample size.

The assemblage is shown by the analysis of the richness and diversity of artefacts of raw material that the assemblage is comprised of 5 different stone types; ironstone, chert, quartz, chalcedony and siltstone. The assemblage was dominated by chert and quartz (55.9 % and 29 %), lesser amounts of ironstone (13.6 %), chalcedony (1.1 %) and siltstone (0.4 %). Slack et al. point out that it is interesting that in the lower spits ironstone is as dominant a raw material as chert and quartz until the massive increase in discard rates that occurred from about 5,000 BP onwards. At about 19,000 BP in spit 14 the first retouch in the assemblage is encountered, sharply peaking at about 7,000 BP in spit 5, the time at which the first evidence of backing is found.

Dominance of complete flakes (81.9 %) (n = 222),  is shown by the fragmentation rate of flakes, with much lower quantities of broken flakes – distal account for 7.7 % (n = 2), proximal for 5.2 % (n = 14) and medial for 4.1 % (n = 11). Until split 3 at about 4,000 BP the ratio broken to unbroken flakes is very low by which time the complete flakes account for 65.2 % (n = 43) and broken flakes account for 34.8 % (n = 23). Slack et al suggest it is probably the result of treadage, with the proposal that the shelter was used more intensively at this time during the Mid-Holocene El Niño arid phase that was experienced in Northern Australia.

Ironstone flakes dominated the assemblage until the Middle Holocene. According to Slack et al. these flakes were generally heavier and had a greater size range, especially between about 15,000 and 5,000 BP. Chert is the dominant raw material after 5,000 BP, with an average weight of the flakes much less than 1 g. It is generally the case that retouched flakes are heavier than unmodified flakes, and with ironstone the retouched flakes are generally significantly heavier.

Analysis of the amount of cortical surface remaining on the dorsal surface of the flake is said by Slack et al. to further support the relationships between the size of complete flakes and extent of their reduction. It is shown by this analysis that ironstone flakes are much more likely than chert to have more cortex, an indication that ironstone flakes have been reduced less than chert flakes. Also, chert and quartz flakes are much more likely than ironstone flakes to have smaller, more reduced platforms, as is evidenced by single and multiple flake scar platforms.

As well as the flaked stone, 857 animal bone fragments were found in the Juunkan-2 site, from a wide variety of species. There were small species such as native rats/mice, lizards and snakes, that made up the majority of the species recovered (61 %, NISP = 523). Medium-large macropods, kangaroos and wallabies, made up 30 % (NISP = 255), and the remainder of the assemblage comprised bird and fish fragments. Among the species identified are red kangaroo, common wallaroo, bandicoot, possum, pygmy possum, echidna, bettong, native mouse, rat, gecko, skink, small bird and fish, the bone fragments being recovered from almost all spits.

In the assemblage all the major skeletal elements are represented, and the fragments of long bone shafts contribute the highest number of fragments (NISP = 120).  There are however, differences in the frequency of elements between the smaller and larger species. Limb bones dominate elements from the smaller species and they are largely unfragmented, a large proportion being of complete skeletal elements. The teeth are most frequently occurring with vertebra being the next most frequents. Contrasting with this, bones from medium-large individuals are highly fragmented and there is a heavy weighting towards fragments of the long bone shaft. The relative paucity of lower limb elements of macropods can probably be accounted for by the fragments of long bone shafts. Teeth from macropods that are medium-large display a mixture of tooth wear stages which range from unworn to extremely worn suggests a mixture of young and old individuals.

Evidence of burning is displayed by 7 % (NISP = 61) of the assemblage, of which 1/3 have been calcined, which suggests they were deposited in fire for longer periods of time following defleshing. The burned bones are from a range of species, and were not confined to any single class of individual. As well as burning, evidence of tooth marks are present on 5 specimens, and 5 fragments recovered from spit 15 show possible cut marks, including the sacrum, pelvis and fragments of long bones of a kangaroo. The faunal assemblage has been shown by taphonomic analysis to represent a deposit that is in situ with rapid burials, because the bones are not weathered and the surfaces of the bones show no physical evidence of either aeolian or fluvial transport.

Slack et al. (2009) suggest faunal analysis at Juunkan-2 may provide important diachronic information about subsistence strategies in the region. Medium macropods, wallaroos, were more common at the beginning of the occupation, and towards the end of the occupation the large macropod (kangaroos) frequency increased, though the majority of species and distributions of skeletal elements appear to have remained consistent over time. As burned and calcined bone, when considered in conjunction of the evidence of hearths, suggests that people were responsible for some of the faunal accumulation, the presence of macropods is therefore considered to probably be a cultural accumulation rather than a natural accumulation. A primary human role in the accumulation is further suggested by the heavy fragmentation of the lower limb bones of macropods, as well as possible cut marks. Yet further evidence that people were involved in the accumulation of bone is the presence of bone from species that are less common such as echidna and fish. It is rare to find preserved faunal remains in rockshelters, and it is suggested that further faunal analysis could potentially contribute significant information with regard to the exploitation of species in the Pilbara for which there is severe shortage of published data.

Sources & Further reading

1. Slack, M., M. Fillios and R. Fullagar (2009). "Aboriginal Settlement during the LGM at Brockman, Pilbara Region, Western Australia." Archaeology in Oceania 44(S1): 32-39.