In summary, a picture o f obsidian use during Lapita/post-Lapita times can be obtained by examination o f assemblages at Kohin Cave, Father's Water, Mouk, Peli Louson and upper levels at Pamwak. The ubiquitous presence o f obsidian in these localities shows that from mid Holocene times obsidian was being regularly moved to both inland and coastal localities on Manus. Indeed, obsidian appears to have been so readily available that even in campsites such as Kohin, where lithic tool production was apparently a relatively minor activity, obsidian was used in preference to local stone. The absence o f a bipolar technique in Lapita or post-Lapita assemblages demonstrates that very small cores were not used in flake production. Obsidian was
The chronological increase in flake size observed between Pleistocene/early Holocene and mid/upper Holocene assemblages at Pamwak is also apparent between Lapita and post-Lapita periods at Kohin and Mouk, although not as marked. This is suggestive that obsidian was more easily accessed by the inhabitants o f these localities after approximately 2500 BP. Whether or not this is a regional pattern awaits further investigation o f sites with occupation spanning Lapita and post-Lapita periods. Synchronic variation in flake size, and hence obsidian availability, is most strongly exhibited between sites on southern Manus and Mouk. At Mouk flakes tend to be larger in both Lapita and post-Lapita assemblages in comparison with contemporaneous Manus assemblages. The obvious explanation for this is that site proximity to source deposits was a major determinant o f the extent to which obsidian was conserved. The inhabitants o f Mouk may have always possessed easier access than the Manus Islanders to obsidian from the neighbouring Pam Islands and Lou. Again, more fieldwork is required to determine whether this is a regional pattern differentiating Manus from the southern islands.
Elongate flakes constitute less than 10% o f pieces in all flake assemblages, with the exception o f the Lapita levels o f Kohin where around 15% o f flakes are elongate. The Kohin assemblage is an interesting case because it represents the only Lapita assemblage so far recorded which possesses a significant proportion o f blade-like flakes. The picture for Lapita flaked lithic technology in Melanesia generally is one o f the production o f undiagnostic flakes (Allen and Bell 1988). I do not see the proportionally large number o f elongate flakes at Kohin as representing a technological innovation accompanying the appearance o f pottery. This is for two reasons. First, elongate and blade-like flakes are present, albeit in small proportions, in Pleistocene and early Holocene contexts at Pamwak (Chapter 4), and second Lapita levels at Mouk contain no elongate flakes.
The stratigraphic location o f retouched microblades at Kohin and Mouk suggests that this flake type is limited to the post-Lapita period. Providing a more secure date for the appearance o f microblades is not possible on present data, but on the basis o f radiocarbon dates for the upper three layers o f Kohin an estimate o f within the last 2000 years may not be far off the mark. The earliest date for retouched blade (point) manufacture on Lou falls around this time (Chapter 3). Obvious technological similarities exist between the production o f microblades and elongate flakes. Possibilities for a direct developmental relationship are discussed in Chapter 8.
Compositional analysis o f obsidian revealed that a regional shift in source use took place in the upper Holocene. The Pam Islands were the major obsidian source during the mid Holocene but by 3500 BP Lou had emerged as equally important. The 5026- 4554 BP date for the Peli Louson obsidian assemblage with its dominance o f Pam Islands material suggests that the increasing use o f Lou obsidian occurred after this time, which fits the general picture for Pamwak (Chapter 4). Unfortunately none o f the sites discussed in this chapter has an unbroken sequence unambiguously spanning pre-Lapita and Lapita periods. Obsidian from Layer 10 at Kohin, which radiocarbon estimates indicate could represent a pre-ceramic midden, has obsidian from both Lou and the Pam Islands (Appendix B). However, sherds were also found in the midden, so if this is to be interpreted as a pre-Lapita deposit then a degree o f mixing with overlying deposits will also have to be accepted. Although the information presented in this chapter for an increase in the use o f Lou obsidian corroborates the picture from Pamwak, we are still not in a position to state whether this occurred with the onset o f the Lapita phenomenon or is associated with other totally unrelated factors, such as the formation o f new obsidian deposits on Lou. This question must be a priority for any future research on obsidian use in the Admiralties.
Inter-locality variability is evident within this broad pattern o f changing source use. At Kohin there is an increase in the importance o f Lou obsidian between Lapita and post-Lapita periods, while the post-Lapita Father's Water assemblage is almost entirely composed o f Lou obsidian. A trend to the late dominance o f Lou obsidian is also evident from the results o f work by Ambrose and colleagues (Ambrose et al. 1981:15) on material from the northern island o f Hus. However, at Pamwak and Mouk the Pam Islands remain an equally important source over the last 2500-2000 years. Although it may be unwise to draw fine distinctions on the relative importance o f obsidian sources given the proportionally small number o f pieces analysed from these localities, the results do tend to suggest that by the post-Lapita period different groups were favouring the utilisation o f particular sources.
CONCLUDING REMARKS
This chapter has examined upper Holocene obsidian use at rockshelters on Manus, and open sites on Los Negros and Mouk. Although this does not by any means provide a full picture o f obsidian use in this region o f the Admiralties, it does reveal change took place in source exploitation and flake production. This evidence corroborates that obtained for Pamwak. The picture is one o f a dramatic increase in the use o f Lou obsidian in the period circa 5000-3500 BP, subsequent post-Lapita dependence on this source in at least some localities, and the appearance o f prismatic blade technology in post-Lapita times. This and the preceding chapter have therefore presented a broad portrayal o f chronological variation in obsidian use since the late Pleistocene. In Part Three of this thesis I narrow the focus to an examination of change in obsidian blade production on Lou over the last 2000 years. This discussion will be undertaken within the context o f the development o f craft specialisation.