Has Anything Changed? The Current Roleof Archaeo-geophysics in Australian Archaeological Research and Cultural Heritage Management

Abstract

In 2012, Australian Archaeology published the paper entitled ‘Review of Geophysical Applications in Australian Archaeology’. The goals of the article were to examine the history of archaeo-geophysics in Australian archaeological research and cultural heritage management (CHM) and consider what factors may have prevented these methods from being utilised in many archaeological investigations to date. It concluded that considerations such as cost, time, instrument availability and lack of theoretical knowledge contributed to the limited uptake of these techniques. This paper also offered suggestions on how geophysical applications were used internationally and whether there was potential for their more extensive use in Australian archaeology. Ten years have passed since this review. Since then, there has been a major increase in the uptake of geophysics in Australian archaeology and CHM. This paper discusses these changes and improvements, and what new opportunities have emerged since 2012. This includes a significant increase in the availability of training in archaeo-geophysics in Australian universities, a deeper engagement with Indigenous communities and the increased availability of equipment.

1 Introduction

The global development of archaeological prospection in Europe and North America has been documented in numerous publications (which are referenced in detail in this edited volume). The initial focus of archaeo-geophysics was primarily on locating material culture items over limited survey areas. Technological advances have allowed for faster data acquisition at the landscape-scale, making it useful for a wider range of research and cultural heritage management projects (Campana & Piro, 2009; Johnson, 2006). The discipline is now moving in a new direction, one that focuses on a more holistic understanding of archaeological sites which includes a consideration of landscape as well as archaeological features and their physical properties. This new approach demands a more nuanced approach to data interpretation and the development of a more rigorous understanding of the relationship between soil properties and geophysical measurements (Cuenca-Garcia et al., 2018). Geophysics is now universally recognised as a cost-effective way to examine the landscape’s topographical, geological, and cultural characteristics. The standard geophysical methods commonly used in archaeological prospection are electrical resistance, electromagnetic conductivity, magnetometry, ground-penetrating radar (GPR) and magnetic susceptibility; all work as tools to map, locate and produce images of subsurface cultural and geological material (Clark, 1996; Gaffney & Gater, 2003; Johnson, 2006).

Despite the demonstrated potential of geophysical techniques to contribute to answering archaeological questions, the growth and development have been considerably slower in Australia than elsewhere. A detailed discussion of the history of geophysics in Australian archaeology has been provided by Lowe (2012) and the aim in this paper is to not present repeated information. Studies discussed therein demonstrated the effectiveness of geophysical methods in the Australian context and considered why these techniques have not been more widely adopted by the Australian archaeological community. In Australia, the most commonly used instruments are GPR and magnetic gradiometry due to their fast, practical nature in site mapping, their popularity with Indigenous communities and GPR’s ability to map in three dimensions. The most common use of geophysical methods has historically been the location of unmarked graves, commonly in collaboration with community or Indigenous groups (Bladon et al., 2011; Brown et al., 2002; Kemp et al., 2014; Long & von Strokirch, 2003; Lowe et al., 2014; Marshallsay et al., 2012; Moffat et al., 2016, 2020a; Powell, 2010; Sutton & Conyers, 2013; Wallis et al., 2008).

In this paper, we consider how Australian archaeo-geophysics has changed over the last 10 years, highlighting a dramatic increase in the use of geophysical techniques and an increasing focus on the integration of geological information into data interpretation and closer collaboration with Indigenous communities. Several new geophysical applications have become popular including a range of techniques that have been applied to a variety of site types in both research and CHM contexts. This includes rockshelters (Barker et al., 2017; David et al., 2017a, b; James et al., 2017; Lowe et al., 2014, 2016, 2018b, 2020; Wesley et al., 2018), shell middens and shell mounds (Kenady et al., 2018a, b; Rosendahl et al., 2014), stone arrangements and rock quarries (Westaway et al., 2021), shipwrecks (Fowler & McKinnon, 2012; Roberts et al., 2017; Simyrdanis et al., 2018, 2019), submerged Indigenous sites (Benjamin et al., 2020; Wiseman et al., 2020), earth mounds (Ross et al., 2019) and historic sites (Lowe et al., 2018a, 2020; McKinnon et al., 2013), along with a continued interest in mapping cemeteries, both Indigenous and non-Indigenous (Bladon et al., 2011; Kurpiel et al., 2019; Lowe & Law, 2022; Lowe et al., 2014; Marshallsay et al., 2012; Moffat et al., 2016, 2020b; Roberts et al., 2021; Sutton & Conyers, 2013).

2 The Australian Context

As Lowe (2012) pointed out, several factors led to geophysical techniques being rarely used in Australian archaeology. Despite this, costs of instruments, time and adequate training are all issues that have seen improvement, as more universities and commercial companies are offering specialised teaching in this area, owning equipment, and providing geophysical services. However, as the practice has moved forward, other challenges have arisen (see Lowe et al., in press). Presently, one of the most significant issues is the nature of Australia’s ancient landscape. Australia has some of the oldest rocks and soils in the world, has not been widely glaciated during the Pleistocene and has extensive areas of mobile sediments in the arid and semi-arid zones. This has several important implications for a geophysical survey; (1) soils that are present are often complex palimpsests having formed over long periods, often over mineralised bedrock and (2) in areas with mobile sediments, erosion is extensive and archaeological material is often conflated by deflation. Such erosional systems do not typically exist in other parts of the world, such as Europe’s Palaeolithic or North America’s Holocene, making it more challenging to understand spatial patterning, adaptation, fire use and occupation intensity of Australia’s past (Holdaway et al., 2017). Therefore, preservation of the archaeological record can, in some cases, be ephemeral based on the geological location of sites and the local taphonomic processes. For example, combustion features—concentrations of heat-fractured rocks clustered together to form a campfire, are often found due to exposure from erosional processes and not in situ (Fanning et al., 2009; Moffat et al., 2008). Deflated landscapes such as this may serve as a detriment for adopting these techniques, particularly in areas that contain complex stratigraphy or depleted landscapes or where seasonal burning may have existed. Due to this, the distribution of many features within archaeological or culturally significant sites varies, making these features poorly understood in many environments.

Taphonomic processes also play a role in understanding sites and the early peopling of Australia and its associated environment. For example, the significant deep-time of continent-wide human occupation has been an ongoing debate in Australian archaeology. Most researchers now accept that Australia was first occupied at least 65,000 years ago (Clarkson et al., 2017). However, a major concern with the ages proposed for early human occupation of sites is based on luminescence dating of sediments rather than cultural materials directly, leaving many to question the association between dated sediments and human activity (e.g., Allen & O’Connell, 2003; Bowdler, 1990; O’Connell & Allen, 2004). In addition, high levels of weathering brought on by climatic changes, rain-splash erosion, bioturbation, and soil mixing are post-depositional disturbances that can contribute to the downward movement of artefacts and other preservation processes (Morley & Goldberg, 2016; O’Connell et al., 2018; Smith et al., 2020; Ward & Larcombe, 2021). Therefore, evaluating the structural integrity of old archaeological sites and the context in which these dated sediments is a critical step in the rigorous investigation of these sites.

Another challenge in Australian archaeo-geophysics is the lack of landscape-scale surveys that have become common in Europe due to the availability of multi-sensor instruments (i.e., Donati et al., 2017; Trinks et al., 2018). A notable exception to this is the detailed survey on an Irish mining settlement at Baker’s Flat (see Lowe et al., 2020), which has demonstrated the important contribution that large scale survey can make to Australian archaeology by mapping a detailed landscape of occupation and confirmed that Baker’s Flat was built in the style of a traditional Irish clachan (Fig. 1). Fortunately, a new National Facility for the 3D Imaging of the Near Surface has recently been funded at Flinders University that will make multi-sensor instruments available for free and provide training to Australian researchers, which we hope will lead to an increase in the use of geophysical techniques on a landscape scale.

Fig. 1

Large-scale magnetic gradiometer survey of the Irish settlement, Baker’s Flat in South Australia with black representing a positive magnetic gradient and white a negative gradient (a). Interpretations of Baker’s Flat site based on geophysical data, excavation, and oral history (b). Note the total hectares surveyed was 2.4 ha; however, the size of the Irish settlement is 60 ha. (Modified from Lowe et al., 2020: Figs. 6 and 14)

Another possible reason for under-utilisation that has also come up in North America, is the language and communication used in geophysical interpretation and presentation (Sunseri & Byram, 2017: 1401). As Sunseri and Byram (2017) pointed out, practitioners need to adjust their ways of thinking and descriptions when delivering results to communities and researchers from other disciplines. For example, the variability of a site, such as texture, form or composition of sediments, should be considered first before making interpretations on likely features or strata, all of which comes from detailed data processing (Sunseri & Byram, 2017). When these variables are considered, one can create careful and methodical ways to disseminate the data to ensure a more meaningful understanding of the results. The ‘shared languages’ of description built around geophysics could complement cultural heritage preservation and the ‘narrative building around archeological partnerships’, which could promote more community engagement and collaboration (Sunseri & Byram, 2017: 1421).

Lastly, despite an increase in peer-reviewed literature and unpublished reports and the potential to inform CHM projects, there is still a limited number of archaeological sites studied (or even identified) for these methods to be applied to (Kurpiel et al., 2019). One reason for this is that the practice of archaeology is a relatively recent field in Australia. With the discipline only starting in the 1960s, the professionalism and expertise to identify and protect sites were low until about the 1980s (Smith & Burke, 2007: 5–8). Australia is also a very large continent, yet the population is relatively small for its size. This means that much of the continent has not been explored archaeologically since European colonisation, and areas that have been investigated today are primarily driven by infrastructure and mining development through CHM. Studies that are carried out in CHM are seldom reported outside peer-review literature or in social media, making it even more challenging to demonstrate its utility and, in some cases, test the methodology.

3 Changes in Geophysical Uptake in Australia

This increasing methodological breadth has been accompanied by a twofold change in approach; firstly, there has been an increased focus on using geophysical techniques to understand human behaviour rather than just locating archaeological sites as had initially been the primary goal (Lowe, 2012). Relevant to this is the increased deployment of laboratory techniques, such as magnetic susceptibility, to better understand features of geophysical anomalies. Meaningful interpretation of geophysical anomalies is currently a major limitation in archaeological prospection and why the Soil Science & Archaeo-Geophysics Alliance (SAGA) was developed (Cuenca-Garcia et al., 2018). The second change in approach has been an increased focus on assisting Indigenous communities with managing their cultural heritage, demonstrated by an increase in the use of minimally invasive studies undertaken with Indigenous community members as co-authors (see Lowe & Law, 2022; Lowe et al. 2018a, Moffat et al., 2008, 2016; Roberts et al., 2021; Ross et al., 2019; Westaway et al., 2021).

One significant development in Australian geophysical studies in the last decade is the foregrounding of hypotheses about human behaviour in research design, rather than focusing specifically on the mapping of geophysical anomalies. An example of this approach is including geophysical survey as an integral part of archaeological excavation of rockshelter sites. These studies use GPR or ERT to map the bedrock geometry and stratigraphic units allowing effective siting of excavation units and placing the excavation results within their broader geomorphic context. This work, which has been published for the Australian sites of Madjedbebe (Lowe et al., 2014), Gledswood (Lowe & Wallis, 2020), JSARN-124 site 3 (Barker et al., 2017), JSARN-113/23 (David et al., 2017a), Nawarla Gabarnmang (David et al., 2017b) and Dalakngalarr 1 (James et al., 2017). The use of geophysics in this context provides a much richer and more nuanced understanding of the archaeological record and facilitates the most effective investigation of these complex sites.

Recent laboratory advances see in Australian geophysical studies include sediment magnetic susceptibility and mineral magnetic characteristics supported by geochemistry and soil micromorphology Some of these studies have been used to determine human activity and the onset of human occupation via anthropogenic burning (Clarkson et al., 2017; Lowe et al., 2016, 2018b). Results show how magnetic enhancement in the shelter’s sediments can assist in understanding initial occupation in deeply stratified sites as the enhancement becomes stronger once people come to the area. Other studies using sediment magnetic susceptibility, sediment analyses and geochronology have shown that shell mounds were repeatedly visited and constructed during multiple phases of occupation than as one single event (Lambrides et al., 2020; Rosendahl et al., 2014; Twaddle et al., 2017). Sediment analysis has also helped in creating volume estimates of buried shell deposits using GPR signatures (Kenady et al., 2018a, b).

Sediment magnetic susceptibility studies have been especially popular in understanding rock shelter stratigraphy (Lowe & Wallis, 2020; Wesley et al., 2018). They provide information on the site formation processes of the archaeological setting, particularly enhanced magnetic values which distinguish anthropogenic from natural site formation processes. Interpretation of the geophysical measurements and soil properties of earth floors at a historical camp revealed that they were made from ant beds or termite mounds, a locally sourced and highly compact material which were the cause of the high-amplitude GPR reflections (Lowe et al., 2018a) (Fig. 2). Lastly, the mineral magnetic characteristics of local slag at the historical Irish settlement in South Australia were the cause of many positive magnetic variations at the site (Lowe et al., 2020).

Fig. 2

An isosurface rendering of the officer’s quarters ant bed floor with GPR transects A, B, and C (a). Reflection profiles for GPR transect A (Profile 030), B (Profile 038) and C (Profile 047) showing the ant bed floor (red line) (b). Coarse-grained particle size analyses show that ant bed floor and ant mound contained the highest fraction of coarser grains (c). Sediment profile of the excavated ant bed (red dashed lines) confirming the reflective planar surfaces (d). (Modified from Lowe et al. 2018a, b: Figs. 5 and 9)

Another meaningful change has been broadening geophysical approaches beyond a methodological focus on GPR and magnetic gradiometry particularly focused on the use of ERT (Ross et al., 2019; Simyrdanis et al., 2018, 2019). Here, ERT has predominantly been used for reconstructing palaeolandscapes associated with archaeological sites, mapping the stratigraphy of archaeological rockshelters, understanding earth mounds and for the 3D mapping of shipwrecks. This change has been brought about by the increased availability of this equipment, particularly due to an ERT equipment manufacturer (ZZ Resistivity) in Adelaide. The use of underwater ERT is a particularly exciting development as it has facilitated the 3D mapping of shipwrecks on the Murray River, which is the third-longest navigable river on the planet and was the inland artery of trade in colonial Australia (Bean, 1911) (Fig. 3a). From the launch of the first paddle-steamer Mary-Ann in 1853 until river trade was made redundant by railways in the early-twentieth century, the Murray River was the major means of transport for wool and station supplies for the booming pastoral industry, making it the most important trade route in colonial South Australia (Fig. 3b). This busy shipping trade has left a submerged record in the Murray River, with nearly 80 shipwrecks known to exist in just the part of the river within the South Australian border. This rich archaeological record has been the subject of several previous investigations (Kenderdine, 1993); however, has always been hampered by the low visibility of the water. As a result, 23% of known wrecks have never been found, and an additional 19% have never been the subject of detailed investigation. Detailed research on the Crowie barge at Morgan on the Murray River has demonstrated that ERT has an important role to play in mapping wrecks that are submerged and sub-bottom in 3D, particularly in situations where they may be too shallow to obtain good results with acoustic techniques (Simyrdanis et al., 2018, 2019) (Fig. 3c). This approach has great potential to be applied in other parts of Australia’s extensive network of inland rivers or in the littoral zone.

Fig. 3

ERT was used underwater to survey the wreck of the Crowie at Morgan on the Murray River. (a) Field survey procedure showing the draping of the ERT cable over the wreck between the river bank (right) and the centre of the river (left). (Image: This One Day Photography). (b) A picture of the Crowie on the stocks at Goolwa in 1911. (Image courtesy of the State Library of South Australia). (c) A 2D ERT profile through the Crowie wreck. (From Simyrdanis et al., 2019)

A final development, has been the substantial growth in Australian-based archaeological geophysicists applying their expertise on international sites including in Cambodia (Duke, 2021; Klassen et al., 2021; Lustig et al., 2018; Moffat et al., 2020a), the Caribbean (Giovas et al., 2019); Cyprus (Lowe et al., 2017), Greece (Donati et al., 2017; Papadopoulos et al., 2015; Sarris et al., 2018; Simon & Moffat, 2015; Simyrdanis et al., 2015), Indonesia (Calo et al., 2022; Maloney et al., 2022), Mongolia (Vella, 2018) (Fig. 4), South Africa (Armstrong et al., 2021; Herries & Fisher, 2008; Herries et al., 2008; Mackay et al., 2022), Papua New Guinea (David et al., 2008, 2009; Moffat et al., 2011), Syria (Casana et al., 2008) and Thailand (Duke et al., 2016). This trend probably reflects the greater availability of geophysical equipment in Australia compared to most countries in the region. However, it might also reflect the lower percentage of trained practitioners compared to the U.S. and Europe, as a majority of international projects were carried out by the author(s).

Fig. 4

GPR being used to map the stratigraphy of the Soyo site in Northern Mongolia by Dr. Bayarsaikhan Jamsranjav, as discussed in Vella (2018)

4 Discussion—What Has Changed?

Since the publication of Lowe (2012), numerous projects using geophysical methods have developed throughout Australia in both research and heritage management. These primarily include magnetic gradiometry and GPR, alongside an increased uptake of ERT and magnetic susceptibility, as discussed above. As mentioned, geophysics has been applied to various terrestrial and marine site types, including rockshelters, submerged landscapes, shell middens and shell mounds, historic sites, and cemeteries, both Indigenous and non-Indigenous and more recently, rock quarries. Such applications and datasets enhance the understanding of archaeological sites and landscape settings. Several Australian researchers were interested in geophysics, but as discussed in the review, they did not have many opportunities to use such techniques or collaborate with a skilled person in the methodology. Perhaps because of the review paper, followed by regional conference presentations, publications, invited guest lectures, and a few training courses within universities and Indigenous communities, there has been an increased uptake and interest in their use. As such, these projects manifested as examples of how these methods could be applied in Australia, forming a ‘web’ of collective research ideas that could be used to address important questions in archaeology and later to assist Indigenous communities in their heritage management (see Lowe & Law, 2022).

The aforementioned web was relatively small during 2011, with less than six professionally known geophysics practitioners in Australia. A key requirement in growing the discipline was to find a way that researchers and Indigenous and non-Indigenous heritage managers could become more familiar with the basic concepts and theory of archaeological geophysics and understand how it could fit into their research and cultural heritage initiatives. To start, presentations were given at school seminars and professional conferences such as the annual Australian Archaeological Association (AAA) in 2008 and 2011 to demonstrate that these applications were feasible in Australian research and publicise their potential. In addition, Flinders University offered a small two-day short course for 20 students as part of AAA 2008, which has now become a biannual 2-week graduate level field school (ARCH8808). This led to more research-driven projects utilising these methods at a variety of different site types while at the same time exploring their use in cultural heritage with commercial consulting companies. As other researchers became aware of the potential of geophysics on their sites, the opportunities transpired, and soon geophysical surveys were being conducted on some of the oldest known sites in Australia (Clarkson et al., 2017; David et al., 2017a, b; Lowe et al., 2016).

With help from colleagues advocating the use of near-surface geophysics within commercial consulting companies, the potential for geophysics grew even more prominent. Around this time, many geophysical surveys were being conducted for First Nations groups, specifically those interested in non-invasive ways to identify unmarked burials. Much of this uptake was related to the short courses offered by Flinders University but also the expertise of the practitioners in project planning. Results from several of these commercial projects were later presented at the AAA conference to highlight their potential and success outside research. Guest lectures at the University of Queensland for a Science in Archaeology course (ARCS2000) were held once a year with about 40 students per course since 2013, and a short course at James Cook University was offered in 2014 for about 25 undergraduate and graduate students, further creating awareness to students. In addition, a session dedicated to remote sensing technologies was offered annually at the AAA from 2013 onwards.

This has been paralleled by a considerable increase in the availability of geophysical equipment within archaeology departments in Australian universities and the inclusion of these techniques as part of undergraduate teaching in field methods courses. Nearly all archaeology programs now have some basic geophysical equipment, and a few have a world-class suite of equipment. Specialised topics in archaeo-geophysics remain rare (only Introductory Archaeological Geophysics at Flinders University) but most field methods courses now incorporate some training in geophysics as part of standard training in archaeology (Fig. 5). Additionally, the number of postgraduate students undertaking research in geophysical topics in archaeology has increased rapidly.

Fig. 5

Undergraduate Archaeological Field Methods students at Flinders University undergoing training in GPR, gradiometry and ERT data acquisition

These more holistic applications of geophysics, beyond traditional anomaly detection, have enhanced our understanding of archaeological sites and landscape settings and have demonstrated the need for such techniques to be evaluated for inclusion in Australia’s legislative and academic frameworks. Currently, in Australia, there is a growing number of cases brought under the Aboriginal and Torres Strait Islander Act 1984 by Aboriginal and Torres Strait groups on threatened cultural heritage sites since the destruction of Juukan Gorge, a 46,000-year-old rock shelter destroyed by a mining company in 2020 (Commonwealth of Australia, 2021). Many practitioners and First Nations groups feel that Indigenous people should be empowered to control their heritage, yet the government has failed to provide custodians with the necessary funding and training to do so. As a result, many are leaning towards archaeo-geophysics as part of the heritage assessment as they can be a more responsible and ethical means of site investigation, particularly for human remains (Sutton et al., 2021) or in situ preservation (Colwell, 2016).

As such, many practitioners have chosen these technologies because they view them as a responsible and ethical means of study in research and consulting and because of their popularity among Indigenous communities (Wadsworth et al., 2021; Warrick et al., 2021). Increasingly, we see a shift towards communities and community-based projects that focus on the use of archaeo-geophysics as part of their heritage management, leading to broader social, cultural, political, and economic impacts for local communities (e.g., Nelson, 2021; Wadsworth, 2019). One example is the geophysical investigations on an area of unmarked Aboriginal mass graves at the Old Cherbourg cemetery in Cherbourg, a town and locality of the Aboriginal Shire of Cherbourg, Queensland, Australia (Lowe & Law, 2022). Formally known as the Barambah Aboriginal Reserve and founded as an Aboriginal settlement in the early 1900s, the Cherbourg community was significantly affected by Spanish Influenza in 1919. At least 15% of the community died from the flu in 3 weeks (Briscoe, 1996). Because the deaths happened so quickly, many were interred in mass graves in areas away from the current Aboriginal community—an area never demarcated. In 2019, 100 years after the event, local Indigenous Elders sought out specialists to carry out non-invasive remote sensing to find the mass grave sites and verify the oral histories about them. It was hoped that the people buried there could receive recognition for their final resting place and have a proper memorial (e.g., plaque or marker).

Using GPR and magnetic gradiometry, in combination with oral histories from the Indigenous community Elders, at least three mass graves were identified (Fig. 6). In the New Cemetery, at least two mass graves were detected, and one mass grave was in the Old Cemetery based on GPR contrasts resulting from soil disturbances (Lowe & Law, 2022). In this example, the community worked together to ensure their values about burial places were respected (and preserved) and that knowledge of the events of the past could be remembered by the community today. According to Eric Law, a Wakka Wakka elder, “We’ve got to remember these people because they are part of our community and they’ll always be a part of our community” (Hegarty, 2019). More broadly, geophysics supported Indigenous aspirations around concepts such as ‘Truth Telling’ which focuses on Indigenous perspectives of colonialism and its impacts today to First Nations people (HCANZ, 2020). In this case, this ensures that Indigenous values about culturally sensitive places such as burials are safe-guarded, and the lives are not forgotten. It also reiterates specific past cultural events of Indigenous significance and their reconciliation efforts.

Fig. 6

Location of the two Cherbourg Cemeteries and the three Mass Graves (a). Overlay (depth 25–50 cm) of GPR amplitude slice map showing strong reflections relating to Mass Grave 3. Oral histories noted that a third mass grave was placed next to the ironbark tree (b). The location of two previously identified mass graves was found in a GPR survey conducted in 2012 (c). Note GPR data was not provided for the 2019 survey but a map showing the location of the unmarked and the two mass graves. Field inspection carried out with the community in 2019 confirmed the mass grave’s location

While this increasing engagement with Indigenous communities is laudable, a challenge remains in transferring geophysical skills and equipment to peoples working outside of academia. No Indigenous or other community groups in Australia currently own their own equipment or have the skills and experience to undertake their own surveys. Similarly, few commercial archaeological organisations use these methods routinely as part of their commercial practice and fewer own geophysical gear. Rather, geophysics is most often employed on more challenging projects, particularly those involving graves, by specialist practitioners. This means that the cost of geophysical methods remains high and is an obstacle to true community self-determination in their use. We hope that this situation has changed should the state of archaeo-geophysics “down under” be reviewed again 10 years hence.

Another major limitation on the use of geophysics to answer questions about the Australian archaeological record is the relatively limited engagement with soil and sediment analysis (except for soil magnetics) by Australian archaeologists. In contrast to the significant increase in the availability and use of geophysical equipment the availability of equipment for soil and sediment analysis in Australian archaeology departments remain limited and training in these areas remains uneven. While this analysis has historically been undertaken in earth science departments, we see great advantage in more closely integrating these methods within archaeology. This has been made more possible due to the rapidly decreasing cost and operational complexity of instruments such as portable x-ray fluorescence and benchtop scanning electron microscopes.

Looking at the projects that have developed since 2012 verifies that a change is occurring and that these methods are being used much more frequently (Fig. 7) and on a wider range of topics within Australian archaeology. While many of the projects involve the author(s), it is evident that geophysical applications in archaeology are increasing, particularly as institutions, consultants, and local custodians learn about the advantages these techniques offer to archaeological research. From 2004 to 2009, publications had doubled for the first time since 1979, 30 years since the initial uptake of these technologies. While globally, training opportunities and geophysics popularity began in 1991 with the U.S. National Park Service course (DeVore, 1992), followed by the first issue of the journal Archaeological Prospection in 1994, this popularity was almost non-existent in Australia—only two peer-reviewed papers were published. Even with the first meeting of the International Society for Archaeological Prospection (ISAP) in 2003, which extended the network outside the U.K., the uptake was still low. However, the most notable change came from 2014 to 2019, where there was a shift in the advancement and acceptance of geophysics in Australia and an increase in contributors, much as what we saw in the U.S. and the U.K. (DeVore et al., 2018).

Fig. 7

Graph showing the number of published papers on geophysical surveys completed in Australian archaeology from 1975 until November 2021. Unpublished material has been omitted due to access availability. Note the significant increase in use in the mid-2000s

Interestingly, in the last 2 years (2020–2021), almost more publications have been generated than in the entire first three decades. Since 2000, there has been a 375% increase in peer-reviewed literature and a 175% increase since 2012. This is a positive outcome notwithstanding the limitations discussed in 2012 and the overall slow uptake. This also supports the initiative of SAGA and the desire to understand soil properties and the processes that affect the geophysical data—as the environmental setting of Australia plays a critical role in data acquisition and interpretation. This is evident in the last 10 years as shown in Fig. 8, where laboratory analyses combined with standard prospecting methods are now being used.

Fig. 8

Graph showing the number of published papers that involve standard archaeological prospecting and those studies that involve both standard and laboratory-based research in Australia

In summary, while challenges still exist today in Australia as well as worldwide in terms of archaeo-geophysics applications and uptake, there is still a slow, steady change in the uptake of digital technologies overall. Perhaps moving away from producing a “pretty picture” or finding things below the surface is what specialists need to do (or keep doing) when moving forward. One example might be to employ more of what Sunseri and Byram (2017) suggested in finding new shared languages for communicating our results to link their potential in interpretation with research design and testing more about what we see in environments that are heavily deflated. By providing suitable languages, researchers and practitioners might have more opportunities to consider the impacts of employing remote sensing technologies as a standard archaeological practice even more and use this information to find ways to address any archaeological challenges. This might ensure their use beyond specialists only, but one where ALL stakeholders have a role in the design, interpretation and output of geophysical investigations. Refining our understanding of the geophysical signatures and how they relate to the human modification of the environment is also a part of this and builds on the limitations discussed in this chapter. The more we aim to bridge the gap between soil properties, geophysics and archaeology, the more we will improve this discipline and its usage in the future.

5 Conclusion

Despite its slow uptake the use of geophysics in Australian archaeology is making an increasingly important contribution to research and CHM. Many of the limitations identified in 2012 no longer exist. However, other problems that need to be factored when moving forward to encourage the use and adaptability of these methods have been identified. In particular, geospatial technologies are an essential tool critical for understanding social and ecological processes and the relationship between people and their environment, especially as they support engagement with the data and management of digital humanities. They also offer another form of visualisation that communities are leaning more towards, given their minimally destructive nature and assistance in conserving heritage landscapes. Yet archaeologists with geospatial expertise are in short supply in Australia.

As geophysical practitioners, we need to continue demonstrating the utility of geophysics in Australia and elsewhere by identifying suitable methods at varying archaeological features and site types and differing depositional settings and reporting both positive and negative findings. Secondly, we should consider building a catalogue of geophysical anomaly types to compare to and help us understand areas where contrasts are questionable. This might assist us when we think about space and how this has been modified by cultural and natural processes—especially processes affected by erosion and degradation. Ground testing anomalies through minimally invasive processes such as soil coring and soil chemical analysis will allow us to understand the geophysical results, providing the ability to accurately interpret the information.

Lastly, we need to continue to work more towards Indigenous and applied archaeology projects driven by communities and where community members hold an active role in all decision-making processes. Workshops are one means by which communities and relevant stakeholders can learn about the methodology and how they can support upkeeping management strategies where applicable. It provides capacity building in the acquisition of new skills that can help Aboriginal communities gain a better sense of when they can apply geophysical approaches to site interpretation. Such knowledge-sharing enhances field searches and creates positive impacts on developing heritage management plans and recommendations at the community level.