Archaeological mitigation in the Perth metropolitan ...

ARCHAEOLOGICAL MITIGATION IN THE PERTH METROPOLITAN REGION Sandra Bowdler, Lynda Strawbridge and Madge Schwede

We describe here recent efforts to structure the management of archaeological sites in the Perth metropditan area, and some suggestions on future mitigation work based on recent and ongoing research. The ideas outlined here arise from several sources. One is a report on the management of Aboriginal sites in the Perth metropolitan region (Strawbridge 1988), commissioned by the Department of Aboriginal Sites of the Western Australian Museum and funded by a National Estate Grant. Another is Schwede's PhD research on the prehistory of the Helena River valley. The other sources of information are a series of mitigation exercises, particularly those involving testpitting, carried out as consultancies in the Perth metropolitan region. Many sites of traditional historical significance to Aboriginal people are known in the Perth metropolitan region, and Aboriginal people often have a view on archaeological sites. These issues are canvassed in Strawbridge's (1988) report, and we regard them as important. It should be borne in mind that management recommendations based only on scientific values may not be sufficient. The Strawbridge report embodies the results of an ethnographic survey carried out separately from the archaeological survey, and makes detailed recommendations regarding specific sites, and also appropriateproceduresfor consultation with Aboriginal people. In this paper, we concern ourselves with archaeological sites and their scientific values only. The archaeological aspect of the Strawbridge (1988) report was made possible because of Hallam's long-term project of research on the Swan Coastal Plain. This project has produced a very considerable data base of site location information based on a systematic program of survey and recording (Hallam 1972, 1977, 1987). The existence of this information made possible assessments of both individual sites and regions in terms of archaeological significance and management needs. One of the problems for archaeologists in the Perth metropolitan region is the consistent lack of good stratified sites. This has been verified not only by a considerable amount of mitigation work, but also by recent purposive efforts by post-graduate students (Schwede, Anderson) to locate such sites. Very few rockshelters are known, and none seem to contain

archaeological deposits. The Orchestra Shell Cave is the only one known, and its archaeological evidence is sparse (Hallam 1974). A cave at Yanchep contained a number of human skeletons, but their archaeological status is far from clear (Crawford 1987?). All other archaeological sites in the region are open sites, of which a few are stratified. Ironically, one of these is the oldest site known in Australia, namely, Upper Swan, fated to 38,000 years BP (Pearce and Barbetti 1981). Some doubts have been expressed as to the authenticity of this claim (Alien l989), but it can be pointed out that some confirmation was obtained from the Helena River site, dated to 29,000 years BP (Schwede 1983). The context of these sites will be discussed further below. Over 600 sites have been recorded. The situation for the Perth metropolitan region therefore is one of a plethora of fragile open sites in a region of continuous development. The Aboriginal Heritage Act (WA) 1972-80 makes it an offence to disturb an Aboriginal site unless authorization to do so has been given by the Trustees of the WA Museum under Section 18. The problem, as addressed by the Strawbridge (1988) report, was to identify how such sites could be assessed, to ensure that sites of significance could be best preserved, and to ensure that all concerned could meet their obligations under the Act without continuous wasteful reduplication of effort. The methods, conclusions and recommendations of the report with respect to archaeological sites are, in summary, as follows.

THE STRAWBRIDGE REPORT Strawbridge (1988) describes the aims and results of Hallam's Swan Area Archaeological Survey, and summarises the main kinds of site found within the Perth metropditan region. She also proposes a series of archaeological research questions which still remain to be addressed. They relate to the themes of site formation processes, site distribution and environmental changes, and stone tool technological change, and follow on from the concerns addressed by Hallam: What processes have acted upon the formation and distribution of Aboriginal sites on the Swan coastal plain?

22 Archaeological Mitigation

Why do so many sites lack evidence of accumulation of deposit? Is this purely the result of urban development or have changing climatic conditions destabilised and degraded any such accumulation? What does the apparent site distribution indicate, and to what degree is it skewed by concentrated urban development? What does the age of the wetland areas imply about the age of clearly associated sites?

metropditan region) and an 'Area B' (Fi.1). The survey for archaeological sites in Area A has been intensive and all accessible areas have been examined. Some parts were not accessible, such as the Swanbourne Army Barracks. Many of the sites in Area A are of significance and could require further investigation, but it is unlikely that any major sites have not been recorded. The survey of Area B however has been far from comprehensive, and it is presumed that many sites within it have not been recorded.

If those wetlands areas were not present when the sea level was lower, what was the pattern and intensity of occupation of the Swan coastal plain and what does this suggest about sites in the different geomorphic zones? Why is the number of sites on the Bassendean Sands formation so high compared to the other zones? How far can the amount of artefact material present at sites be taken as an indication of population changes? To what extent might technological innovations produce changes in the amount of artefact debris produced? Which sites might contain further archaeological material in a clear sequence and with dateable samples to support or dispute the existing scheme of technological changes? If the supply of fossiliferous chert found on sites was lost when the sea level rose, can we detect technological changes in assemblages as a result of the decline of this stone resource? The importance of researchquestions is emphasised in the report in the fdlowing words: Research should be monitored. Where research into the cultural resource involves excavation of a deposit or will disrupt the resource in any other way, it is important that this should contribute further information to an understanding of the nature of the resource than has already been gained by previous research, and that it involves a planned research framework ... The existence of a regional research framework enables data to be cdlected in such a way that it contributes to current research questions, thus increasing the usefulness of such data (Strawbridge 1988:22). We return to the question of excavation below. The Swan Area Archaeological Survey (Hallam 1972, 1977, 1987) d M e d the Perth metropolitan region into an 'Area A' (covering most of the more central

Figwe l

Perth metropolitan region

All sites were mapped, both archaeological and ethnographic. The series of maps produced to accompany the report show the location of all known Aboriginal sites at the time of preparation, and constitute an important planning tool in itself. A computer analysis was carried out of 567 archaeological occupation sites for which sufficient information was recorded. These are all open sites represented by a surface scatter of stone artefacts. Information used in the analysis induded which geomorphic zone each site occurred in, the nearest water source, artefact assemblage data, possibility of subsurface deposits being present, size, condition, distance from coast and so on. Sites were also

Bowdler, Strawbridge and Schwede 23

classified according to the phase to which they were assigned by the Swan Area Survey, and were grouped into size classes based on the estimated density and total number of artefacts. This analysis is presented in the report in a series of tables and graphs. Geomorphic Zone

Number Of Recorded Archaeological Sit-

Quindalup Dunes Cottesloe Limestone Karrakatta Sands Bassendean Sands Alluvial Deposits Foothills Darling Range Total

Table 1

613

Archaeological occupation sites by geomorphic zone (from west top, to east -bottom) in the Perth metropolitan region

-

We will discuss here in moredetail the attribution of sites to geomorphic zones. These data are presented in Table 1, and in this instance include all known archaeological sites, not just those included in the computer analysis. The Quindalup Dunes, Karrakatta Sands and Bassendean Sands are dune systems of increasing age, so that the Bassendean Sands are the oldest and most heavily leached. Chains of lakes and swamp lands occur along the eastern margin of this zone towards the foothills of the Darling Range. This abundance of resources may account for the large number of sites in this zone. The Alluvial Deposits are also associated with water sources, as they consist (as the name suggests) of alluvium carried from the range and foothills by rivers and streams, and deposited along their lower reaches. This formation includes the Upper Swan and Helena River sites. Number

%

Sites with little further research potential

Isolated artefacts

29

5.1

Sites already destroyed

123

21.7

Sites partially disturbed, no research potential

188

Sites partially disturbed, some useful data

14

Sites wtth further research potential (including historical significance)

213

Tabk 2 Sites included in analysis of significance assessment

The report assesses all known archaeological sites in terms of their potential for research, and on this basis assigns them to classes within two categories Fable 2). On the one hand are sites with little further research potential, including isolated artefacts, sites already disturbed by development, sites partially disturbed but not of significant research potential, sites partially disturbed which may retain some useful data. On the other hand, there are sites with further research potential; these are all sites which have suffered little or no disturbance, some of which occur in geomorphic zones with low numbers of known sites, some of which have insufficient information recorded to determine their status, and which overall provide a representative sample of archaeological sites in the metropolitan region. A special category of sites of significance in the history of research in the region is recommended for preservation; these comprise Walyunga (Darling Ranges; Pearce 1978); Upper Swan (Alluvial Deposits; Pearce and Barbetti 1981) and Orchestra Shell Cave (Cottesloe Limestone; Hallam 1974). In this way, all recorded archaeological sites are assigned to a category to which specific recommendations apply. The report discusses the Perth metropolitan region planning scheme, which came into effect in 1963, and its strategies and administration. The principal strategy involved defines four urban corridors of development. The responsibility for dealing with most applications for development in the first instance resides with local government authorities. The report therefore discusses the four corridors in turn, and within each, the number of archaeological and ethnographic sites known within the boundaries of each local authority is described. The report makes recommendations in terms of both areas of land and of specific sites. These recommendations are generally. procedural, in that they identrfy what actions would be most appropriate in a given situation relative to a given area of land. The first recommendation is based upon the fact that, in general, any part of the Perth metropolitan region falling within Area A as defined in the report has been intensively surveyed for archaeological sites, apart from those areas previously inaccessible (defined inthe report). Even if any small sites remain unrecorded in Area A, they will inevitably have been disturbed. It is therefore recommended that further survey for archaeological sites in Area A is not necessary. Much of Area B, the remainder of the Perth metropolitan region, has not been systematically surveyed. The report describes which parts of Area B have been surveyed, and recommends that further survey of these regions is not necessary. All other parts of Area B should be surveyed prior to development. The report makes further recommendations with respect to land and sites in several categories:

24 Archaeological Mitigation

Firstly, areas of land requiring examination in the short term are defined. These are areas considered likely, on the basis of recorded site analysis, to contain sites, and which are also subject to development in the near future. Secondly, archaeological sites which require examination in the short term are identified. These are sites which appear to contain data relevant to research which are threatened by development activities in the near future. Thirdly, undeveloped areas of land which are likely to containarchaeological sites and which are likely to provide good opportunities for management and preservation of a sample of archaeological sites are identified. Fourthly, an overall sample of known sites representative of the range of sites in the Perth metropolitan region is identified for management and preservation. Finally, recommendations concerning ethnographic sites are made, based on the findings of the ethnographic survey embodying consultation with relevant Aboriginal people. The report concludes with an outline of management considerations, and suggested guidelines and procedures for developers. It is expected that local government authorities, government departments, companies, consultants, and other groups or individualswishing to develop any land within the Perth metropolitan region, would consult the Strawbridge report and its accompanying maps in addition to consulting with Aboriginal groups to ascertain what action is appropriate to discharge their responsibilitieswith respect to Aboriginal sites, before making an application with respect to such sites.

Test-pits in the Perth Metropolitan Region One of the issues which the report does not discuss in detail is the issue of test-pitting archaeological sites in the Perth metropolitan region. Sufficient test-pits (Table 3) have now been excavated in archaeological sites on Bassendean Sands to warrant the conclusion that any more would be a complete waste of time and money.

Rsannndean Sands Alluvial Dt~posits COttesloe Limestone Karrakatta Sands Darling Range foothills

As noted above, there are very few stratified archaeological sites in this region. Orchestra Shell Cave (in Cottesloe Limestone) is the only known rockshelterl cave site with stratified archaeological deposits. With respect to open sites, only three to f i e are known with any kind of stratigraphic integrity, and these are not all straightforward cases. Upper Swan (known locally as Upper Swan Bridge) (Pearce and Barbetti 1981) and the Helena River site (Schwede 1983) both consist of stone artefacts and scattered charcoal stratified within Alluvial Deposits, which are of Pleistocene age. It is argued that radiocarbon dating of charcoal samples shows occupation at Upper Swan ca 38,000 years ago, and at Helena River, between 2100 years BP and 29,000 years BP The association of charcoal and artefacts, and the stratigraphic integrity of these sites, must be conceded to be open to argument. Mitigation work was carried out in 1985 on sites also located in Alluvial deposits in the Swan Valley at Millendon (Schwede 1985). Test-pits were dug at three sites, of which one was thought to be in deposits similar to those of Upper Swan. Artefacts were again associated with scattered charcoal dated to ca 8000 years Be but there were problems here both with the dating and with the interpretation of the sediments. These sites are clearly problematical, but it is also obvious that sites occurring in the Swan River Alluvial Deposits have the potentialfor archaeological research significance. A site at Walyunga (Pearce 1978) has produced what appears to be a perfectly coherent occupational sequence spanning the last 8000 years. This site appears to have considerable stratigraphic integrity, although not perhaps as much as has been implicitly claimed. It is unique in its geomorphic context, as it is located in a sand dune which is part of the Yoganup formation, comprising fossil shoreline sands on the Ridge Hill Shelf.

All other sites which have been test-pitted in the Perth metropolitan region occur on Bassendean Sands (Table 3; Anderson 1983; Brown 1983a, 1983b, 1983~, 1983d; Pearce 1979; Schwede 1984b; Strawbridge

Bowdler, Strawbridge and Schwede 25

1984; Strawbridge and Veth 1989). Only one of these has been dated, at North Lake, to m 2200 years BP (Pearce 197937);little other information is available. In general, these sites haveall been considerablydisturbed. Anderson (1983) recognised that the Bassendean dune system consisted of a stable core with a superficial moble layer of continually reworking sands within which artefads may have been deposited over a long time, but which became completely mixed on one level due to continual deflation. Schwede (1984a, 1984b) has also high-lighted the role of European farming practices in disturbing these sites ever further

The fact that most recorded sites do in fact occur on Bassendean Sands presents problems both practical and intellectual. On the one hand, the number of sites which have now been tested convinces us that it is likely that they are all seriously disturbed, either by natural processes, farming and other European activities or (usually) both. On the other hand, the large number of sites on this formation may be due either to this continual process of erosion, which reveals them, or to a recent intensification of occupation (Strawbridgeand Veth 1989). The irony is that, because of reworking, these propositions cannot be directly tested by excavation. The most immediate management conclusion to be drawn is that there is little point in attempting further research on these sites, unless new methodologies,and new research questions, are developed. Further test-pitting of archaeological sites on the BassendeanSandsfor scientific purposes as part of mitigation measures are, we repeat, a waste of time and money. A more general conclusion may be drawn about the usefulness of an extensive archaeological data base in developing management strategies in an area such as this which is continually undergoing heavy development demands It is clear to us that such a data base needs to be organised into a suitable framework for consuttants and developers to make the best use of it. It is also clear that, unless consultants familiarise themselves with all appropriate previous work, of both a research and a mitigationnature, much redundant effort may beexpended Onthe other hand,adequate researchcombined with some attempt at synthesis in a management framework will combine to both minimise the effects of development and maximisethe efforts of archaedogists.

NOTE 1.

True at time of writing, and possibly still true.

REFERENCES Allen, J. 1989 When did humans first colonize Australia? Search 20: 14 9 4 3 Anderson, J. 1983 Test pits and supplementary survey at Perth krport , Western Australia. b p o r t to the Department of Housing and Construcbon, Perth

Brown, S. 1983a Beechboro-GosnellsCAH. Guildford Roadto Morley Drive. Test excavations at Aboriginal site no 50170. Report to Main Roads Department, Perth Brown, S. 1983b Fieddiffe-Bushmead Highway H19. Great Eastern Highway to Floe Highway. Test excavation at Aboriginal site no.W726. Report to the Main Roads Department, Perth Brown, S. 1 9 8 3 ~Beechbordjosnells C.AH. Newbum Road to Roe Highway, (Forestfield Railway Bridge). Test excavation at Aboriginal site no S1437. Report to Main Roads Department, Perth Brown, S. 1983d BeechborGosnells CAH. Newbum Road to Roe Highway (Forestfield Railway Bridge). Test excavation at Aboriginal site no S1336 Report to Main Roads Department, Perth Crawford, I.M. l98i? Draft report on Yonderup Cave, Yanchep,Western Australia. Report to the Department of Aboriginal Sites, Western Australian Museum, P e h Hallam, S.J. 1972 An archaeological survey of the Perth area, Western Australia: a progress report on art and artefacts, dates and demography. Australian Institute of Aboriginal Studier Newdetter 3(5):11-19 Hallam, S.J. 1974 Excavationsin the Orchestra Shell Cave, Wannerw, Western Australia. Part I - Ethnographic and environmental background. Part I1 - Archaeology. Archaedogy and Physlccll Anthropology in Oceania 9:66-84, 134-55 Hallam. S.J. 1 9 n Topographic archaeology and adifactual evidence. In R.V.S Wright (ed.), Stone T d s as Cultural Markers, pp.169-77. Australian lnstitute of Aboriginal Studies: Canberra Hallam. S.J. 1987 Coastal does not equal littoral. Australian Archaeology 25: 10-29 Pearce, R.H. 1978 Changes in the artefact assemblages during the last 8,000yearsat Walyunga,WesternAustralia. Journal ofthe Royal Society of Western Australia 61: 1-10 Pearce, R.H. 1979 Analysis of some Western Australian small tool assemblages. MA thesis, Universityof Western Australia, Perth Pearce, R.H. and M. Barbetti 1981 A 38,OOOyear old archaeological site at Upper Swan, Western Australia. Archaeology in Ocesnia 16.1734 Schwede, M.L. 1983 Supertrench - phase two: a reporton excavation results. In M. Smith (d.), Archaeology at ANZAAS 1983, pp.5242. Western Australian Museum: Perth Schwede. M. 1984a Lupinus, scatters and excavations: site formation in action. Paper presented at Australian Archaeological Association Annual Conference,Budeigh Heads, November 1984 Schwede, M. 1984b A report on archaeological excavations at Bennett Brook sites S1431 and S1940. Reportto DamesandMoore,Perth Schwede, M. 1985 Archaeological trial excavations of sites S1707, S1315 and S1319 at Brigadoon Country Estate, Millendon, Western Australia. Report to T.S. Martin and Associates, Perth Strawbridge, L 1984 Further test pitting and survey at Perth Airport, Western Australia. Report to the Department of Housing and Construction, Perth Strawbridge. L 1988 Aboriginal sites in the Perth metropolitan area: a management scheme. Report to the Department of Aboriginal Sites. Western Australian Museum, Perth Strawbridge. L. and P. Veth 1989 Report of testpits carried out at sites SCXH and S2466at Jane Brook, Perth Metropolitanarea. Western Australia. Report to G.R. Crimp and Partners. Perth.

Department of Archaeology University of Western Australia Nedlands WA 6009