By Michelle C. Langley. Based on two articles from Australian Archaeology 75.
Archaeology has a long history. People have always speculated about the past and most cultures have origin stories about how they came to exist and why. However, archaeology—the undertaking of excavation and careful examination of artefacts to learn about the past—only began in the eighteenth and early nineteenth centuries when especially curious and adventurous researchers began to dig at some of the most famous ancient sites (such as Pompeii, Stonehenge and Troy). These early digs were far from the careful and scientific excavations that are undertaken today. Early researchers were primarily concerned with finding ‘exciting’ artefacts, burials, or buildings and didn’t consider the remaining (often broken or ‘boring’) ones, or even the context (where and how an artefact is found) in which they were found, worthy of study.
Now, archaeologists know that the context in which artefacts are found provides the most important information for learning about past peoples. Consequently, modern excavations take great care to record every aspect of the site being investigated. This careful recording is essential as excavation is a destructive process—artefacts are removed from their original location and their relationship with other artefacts and the site itself will be lost if not carefully recorded.
Similarly, determining how old an artefact is or what it is made from often requires that small pieces of the object are removed for analysis in various laboratory-based machines. These samples are often destroyed or altered during analysis. Thus, archaeologists are constantly looking to develop or integrate new technologies which minimise the impact (the damage) on the artefacts and sites which we study.
In the last decade, a multitude of new technologies have become available to researchers allowing them to undertake more sophisticated analyses in the field and minimise the impact on the archaeology. These technologies include iPads, digital surveying equipment which records each individual artefact in three-dimensional (3-D) space, portable microscopes, digital scanners which can photograph entire sites in 3D, and portable spectrographic units.
In Australian Archaeology 75, the results of two projects which used a particular technology to analyse artefacts—portable x-ray fluorescence (PXRF)—are presented.
In the first paper, Jillian Huntley discusses how PXRF can be used to analyse rock art in the field without need to take samples for latter examination in a laboratory. This portable machine can be set up in front of the painting which the researcher wants to study, and, by firing x-rays at the pigment (the paint) can identify what the pigment is made from (its chemical composition). When this information is compared to that of other pigments from other paintings and ochre sources in the surrounding landscape, it can then tell us where the materials used to make the paint were collected and, sometimes even tell us how they were prepared.
Using this technology, Jillian undertook analysis of two anthropomorphic motifs (human-like figures) painted on the walls of a rockshelter on the Woronora Plateau in the Illawarra region of New South Wales. Her results indicated that the pigment used to make these paintings were clay-based and locally sourced, meaning that the artist/s did not have to travel a great distance to collect the clay before making the paintings.
In the second paper, Grant Cochrane and colleagues used PXRF as part of their analysis of lithic (stone tool) artefacts from Arcadia Valley, central Queensland (Australia). Made from a type of stone called silcrete, a sample of 40 artefacts were analysed using PXRF in order to determine their geochemical composition. The results indicated that the stone may have come from more than one source, suggesting that the ancestors of the local Aboriginal people (the Karingbal) who lived in the region more than 2,000 years ago visited more than one quarry site to collect raw material for making their technology.
Knowing what materials (for example, ochre, clay or charcoal) were used to make paints used in rock art, or from which outcrop of stone tools were made, can tell us much about past peoples. For example, it can tell us how far people travelled to collect supplies to make their art and tools, or how far the raw materials or tools were transported away from where they were originally collected and/or made.
Knowing where raw materials originally come from, also allows archaeologists to investigate if certain materials were traded between groups and if they were considered ‘valuable’, through identifying how widely distributed they are as well as how much of each material was traded/transported and the types of artefacts made from it. This information, in turn, gives us insights into how neighbouring groups interacted with other many thousands of years ago.
These data obtained through the use of new technologies, together with information given by the traditional owners (the Indigenous Australians who have lived in the area for many thousands of years) allow archaeologists to build an understanding of the prehistory of Australia and its people.
For further information on the analysis of Australian rock art see:
Chippindale, C. and P.S.C. Taҫon 1998 The Archaeology of Rock Art. Cambridge: Cambridge University Press.
Flood, J. 1997 Rock Art of the Dreamtime. Sydney: Angus and Robertson.
Morwood, M.J. and D.R. Hobbs 2002 Visions from the Past: The Archaeology of Australian Aboriginal Art. Washington D.C.: Smithsonian Institution Press.
Whitley, D.S. 2005 Introduction to Rock Art Research. Walnut Creek: Left Coast Press.
For further information on the analysis of lithic artefacts see:
Hiscock, P. 2008 Archaeology of Ancient Australia. London: Routledge.
Holdaway, S. and N. Stone 2004 A Record in Stone: The Study of Australia’s Flaked Stone Artefacts. Melbourne: Museum Victoria.
Odell, G.H. 1996 Stone Tools: Theoretical Insights into Human Prehistory. New York: Plenum Press.
For further information on the use of PXRF to analysis artefacts see:
Shackley, M.S. 2011 An introduction to x-ray fluorescence (XRF) analysis in archaeology. In M.S. Shackley (ed.) X-Ray Fluorescence Spectrometry (XRF) in Geoarchaeology, pp.7-44. New York: Springer.