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Title
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The Use of Geophysical Survey in Archaeology
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Author
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Horsley, Timothy J.
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Research Area
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Methods of Research
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Topic
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Research Methods ‐ Quantitative
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Abstract
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This essay aims to introduce readers to geophysical methods that are currently employed to help archaeologists study the past. Geophysical techniques exploit differences between the physical properties of buried remains and the natural soil to allow their detection and characterization without—or in advance of—digging. When successfully applied, they have the potential to dramatically enhance archaeological investigations by providing a map of buried remains that can (i) help to assess an area for its archaeological potential; (ii) guide subsequent excavation; or (iii) be used as a tool to define and test research questions in their own right. Given the relatively rapid and noninvasive nature of these methods, it is possible to examine entire sites and landscapes, in some instances detecting features as small as individual post holes. While these techniques are routinely integrated into archaeological investigations in some parts of the world, their potential in many areas is only starting to be realized. It is expected that we will see continued growth in the number of surveys being conducted, as well as in the sizes of areas encompassed and in the range of their archaeological application.
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Identifier
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etrds0356
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extracted text
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The Use of Geophysical Survey in
Archaeology
TIMOTHY J. HORSLEY
Abstract
This essay aims to introduce readers to geophysical methods that are currently
employed to help archaeologists study the past. Geophysical techniques exploit
differences between the physical properties of buried remains and the natural soil
to allow their detection and characterization without—or in advance of—digging.
When successfully applied, they have the potential to dramatically enhance
archaeological investigations by providing a map of buried remains that can (i) help
to assess an area for its archaeological potential; (ii) guide subsequent excavation;
or (iii) be used as a tool to define and test research questions in their own right.
Given the relatively rapid and noninvasive nature of these methods, it is possible
to examine entire sites and landscapes, in some instances detecting features as
small as individual post holes. While these techniques are routinely integrated
into archaeological investigations in some parts of the world, their potential in
many areas is only starting to be realized. It is expected that we will see continued
growth in the number of surveys being conducted, as well as in the sizes of areas
encompassed and in the range of their archaeological application.
This essay will briefly introduce the major geophysical techniques and types of
buried features that may be detected. Recent developments in various aspects of the
discipline are then summarized, before discussing ways in which the results may be
applied more broadly in future archaeological and anthropological investigations.
INTRODUCTION
In the last few decades, geophysical survey—sometimes referred to as
shallow geophysics or remote sensing—has become increasingly established as
a routine part of archaeological investigations around the world (Clark, 1990;
Gaffney and Gater, 2003; Johnson, 2006; Linford, 2006; Scollar et al., 1990;
Weymouth, 1986). This term refers to a suite of noninvasive, ground-based
techniques that measure a physical property at or just above the ground
surface to discover and map a range of buried archaeological remains.
Geophysical survey is therefore distinct from investigations that employ geochemical analyses or airborne and satellite based remote sensing equipment,
Emerging Trends in the Social and Behavioral Sciences. Edited by Robert Scott and Stephen Kosslyn.
© 2015 John Wiley & Sons, Inc. ISBN 978-1-118-90077-2.
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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES
although the various datasets these other methods produce are often complementary.
Geophysical techniques can be used to detect and characterize buried
cultural remains without excavation. Features such as walls and pits can
usually be located, but in general it is not possible to detect artifacts, such
as pots or coins. The results are often used in advance of archaeological
excavation, sometimes alongside it, or occasionally instead of such invasive
testing. Thus, they can be an invaluable tool for assisting a range of archaeological investigations. Not only do geophysical surveys help to target
specific features for excavation, but also they may be used to examine and
map entire sites and landscapes at a level of detail that could not be achieved
using more traditional archaeological methods. In this way, the data they
generate can be used to investigate the use of space and the relationships
between sites and the natural and cultural landscapes in which they are
situated.
Past human activities that have altered the natural arrangement of buried
soils and sediments may give rise to detectable geophysical anomalies. When
correctly interpreted, these anomalies reveal the presence of their causative
features. In this way, it can be possible to identify buried remains ranging
from individual features to entire sites and landscapes without disrupting
the ground.
Geophysical methods therefore offer archaeologists another tool to help
study the past, both by helping to situate excavations to obtain cultural material for identifying who occupied a site, for how long, and when, but also
as a powerful research tool in its own right. These two goals are not mutually exclusive: the results from geophysical survey and excavation assist and
inform each other to further enhance the understanding of both and develop
new hypotheses for testing.
Analysis of geophysical results is often assisted by data treatment and processing to enhance archaeological responses, and the data can then be integrated with other forms of data using a GIS to aid interpretation and help
situate the findings. Since these methods are not detecting buried features
directly, but rather geophysical anomalies that require interpretation, a successful survey is related to many factors, including the type of archaeological
remains present, the natural ground conditions (soil, geology, etc.), and the
particular geophysical method(s) being employed, as well as experience in
applying and interpreting the results.
Current advances in this field relate to the techniques and methodologies
for data collection, processing and interpretation, but also to ways in which
geophysical surveys can be applied to help us learn about the past.
The Use of Geophysical Survey in Archaeology
3
FOUNDATIONAL RESEARCH
A number of geophysical techniques can be employed for archaeological
prospection. Each method exploits variations in a particular physical
property associated with subsurface conditions and has been developed
to respond to the subtle changes associated with buried archaeological
features (such as structural remains, hearths, pits, and post holes), and
anthropogenic deposits (such as midden deposits—refuse associated with
human occupation). Other features that can be detected include agricultural
disturbances (e.g., plowing), pedological and geological changes (e.g., lenses
of differing material and bedrock), and geomorphological features (e.g.,
palaeochannels).
For a buried feature to be detectable there must be a physical contrast
between it and the surrounding natural soil or sediment; if no contrast exists
the feature will essentially be invisible. The success of a particular technique
is therefore dependent on the physical properties of the feature itself, local
conditions, (such as soil type and depth, parent material, etc.), as well as an
ability to correctly interpret the data. Since no single method will be able
to detect every trace of human activity at every site, it is important that the
appropriate method(s) is employed. In recent years, a number of books and
articles have been written about the geophysical techniques employed in
archaeology, and only an overview of the major techniques is provided here.
This is followed by a brief introduction to typical field methodologies, and
approaches for data treatment, processing and visualization. The reader is
advised to look to the citations provided at the end of each section for more
detailed descriptions, historical development, case studies, and additional
references.
COMMON GEOPHYSICAL TECHNIQUES IN ARCHAEOLOGY
The most commonly applied geophysical method in archaeological investigations around the world is magnetometry. This method can detect a wide
range of features in many environments and, due to its speed, portability,
and relative ease of interpretation, is frequently used as the first or only survey method. Different types and configurations of magnetometer are available, but each instrument measures subtle variations in the Earth’s magnetic
field. Human activities that have altered the natural distribution of weakly
magnetic iron oxides in the soil (e.g., digging), or converted them into more
magnetic forms (e.g., through burning), can result in contrasts in magnetic
susceptibility (MS) that result in local distortions in the geomagnetic field. MS
is a measure of how readily a material is magnetized when placed in a magnetic field, a property that is determined by its composition—in particular the
types and concentrations of iron minerals present. In this way, pits, ditches,
4
EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES
house basins, hearths, and sometimes post holes can be detected on account
of slight variations in MS. Buried remains associated with kilns and furnaces
that have been exposed to high temperatures can possess an intense permanent magnetization, as can bricks, tiles, and also some igneous and metamorphic rocks. Many of these archaeological features produce characteristic
magnetic anomalies that can allow their identification. [Further details on
this technique may be found in Aspinall, Gaffney, and Schmidt (2008), Clark
(1990), Gaffney and Gater (2003), Kvamme (2006b), and Linford (2006).]
Magnetic susceptibility may also be used as a prospection and analytical tool
in its own right. Measurements of soil MS, either on site or on samples taken
back to the laboratory, can reveal magnetic enhancement that may be correlated with human activity. This method can be used as a reconnaissance tool
to locate areas for further investigation, either across a landscape or down
boreholes, or as an interpretive tool during excavation or coring. In addition
to locating anthropogenic features, MS can be used to better understand both
site formation and post-depositional processes, and in environmental reconstruction. For more details see Dalan, 2006; 2008; and Gaffney & Gater, 2003.
Further details are provided in Conyers (2004, 2013); Conyers and Goodman (1997); Gaffney and Gater (2003); Goodman and Piro (2013); Leckebusch
(2003); and Linford (2006).
Earth resistance—also known as electrical resistance or resistivity—measures
the resistance of the ground to an applied electrical current, essentially providing a measure of the water content of buried soils and sediments. Past
activities that have altered the natural compaction and porosity of the soil,
(e.g., the digging and backfilling of pits and ditches, or the introduction of
stone or brick foundations), may have changed the resistivity of the soil and
therefore be detectable. In archaeology, measurements are most commonly
collected across an area to produce a horizontal map, although many workers use this method to investigate vertical sections through the ground (e.g.,
in electrical imaging and pseudosections). In each case, electrodes are required
to pass a current through the ground and take measurements; different electrode configurations and separation distances can be employed for different
purposes, such as investigating different depths. Interpretation of resistance
data can be complicated by natural variations in soil moisture due to topography, drainage, and even recent weather conditions. Further details and case
studies can be found in Clark, 1990; Gaffney & Gater, 2003; Linford, 2006;
Somers, 2006; and Schmidt 2013.
Electromagnetic induction methods, often simply referred to as EM or EMI,
can be used to simultaneously obtain information about both electrical conductivity (the inverse of resistivity) and magnetic susceptibility of the subsurface. This method, frequently employing so-called slingram devices, has
shown good correlation with earth resistance and magnetic surveys in many
The Use of Geophysical Survey in Archaeology
5
different environments and can detect many of the same features in a single
instrument without the need for electrical contact with the ground. However,
despite these obvious benefits, it has not been as widely adopted in archaeological investigations as the previously described techniques. One reason
for this may be that the readings obtained are the result of a complex combination of factors (including the size, shape, and orientation of the conducting object/feature), which can make interpreting the results difficult. As this
technique allows measurements of electrical conductivity without requiring
electrodes to make contact with the ground (unlike earth resistance), it may
be used over highly resistant materials such as sand. (Further details on this
method may be found in Bigman, 2012; Clay, 2006; Linford, 2006; Tabbagh,
1986; Thiesson et al., 2009.)
In the last decade, ground-penetrating radar (GPR)—also an electromagnetic method—has become much more frequently employed in archaeology
and has the potential to provide a greater degree of information about buried
features. In contrast with most other methods that produce two-dimensional
maps of anomalies, GPR provides a view of subsurface variations as a
slice through the ground, thereby allowing vertical relationships between
features to be assessed. Data collected along many closely spaced profiles
can be combined to produce a three-dimensional block of data, from which
horizontal time-slices can be extracted to reveal reflections at different
depths. The GPR antenna transmits pulses of electromagnetic energy that
are reflected back to a receiver whenever they encounter a change in
material. This method can be used to identify sub-horizontal features (e.g.,
floor surfaces and soil horizons), vertical features (e.g., trenches, walls),
and discrete features (e.g., pits, rocks and voids). In addition to the depth
information that this method may provide, it can also be used over floors
and therefore has potential within buildings. GPR time-slices can resemble
excavation plans from different depths and so are more easily understood
by nonspecialists than the vertical profiles, and animations that simulate
stripping away the soil offer an informative and eye-catching presentation
of the results. Further details are provided in Conyers (2004, 2013), Conyers
and Goodman (1997), Gaffney and Gater (2003), Goodmand and Piro (2013),
Leckebusch (2003), and Linford (2006).
A range of other methods are available that have had limited application
answering specific archaeological questions to date. These include seismic
methods (e.g., Goulty & Hudson, 1994; Ovenden, 1994; Vafidis et al., 2003),
microgravity (e.g., Linford, 1998), self-potential (e.g., Drahor, 2004), and
induced polarization (e.g., Shleifer, Weller, Schneider, and Junge, 2002). The
reader is advised to look to these references for further information.
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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES
FIELD METHODOLOGY
For the majority of the geophysical methods described above, measurements
are made at regular intervals within grids of squares established over the area
to be surveyed. The resolution of data collection will often be determined by
the expected feature dimensions, (features smaller than the sample interval
will be difficult or impossible to detect), as well as how much time is available for survey. Since many instruments do not have an integrated global
positioning system (GPS), (although this is changing—see below), the spatial
accuracy of measurements relies on the operator. Survey grids are usually
later tied into known features or real world coordinates using total station
instruments or GPS.
DATA PROCESSING, ANALYSIS AND VISUALIZATION
A number of dedicated software packages exist for the treatment and processing of geophysical data. Such post-processing is usually necessary to (i)
correct data collection defects such as incorrect line lengths or inconsistencies
in measurement location; and (ii) reduce natural or other unwanted background variations while enhancing anomalies of interest. Appropriate presentation and visualization of data is then essential for analysis and interpretation, with geographic information systems (GIS) frequently employed
to facilitate mapping with other sources of spatial data and presentation of
the results. Other areas of ongoing research in GPR data analysis relate to the
challenges of precise depth estimation (e.g. Leckebusch, 2007), and improving data interpretation (e.g. Bönige & Tronicke, 2010; Leckebusch, Weibel, &
Buhler, 2008; Schmidt & Tsetskhladze, 2013).
It should be stressed that these techniques detect geophysical anomalies
and not the subsurface features themselves, and therefore the data require
interpretation. This requires a certain degree of experience, both with the
instrumentation and also the types of archaeological sites and features in a
given region. As many different buried features, both natural and archaeological, can produce similar geophysical anomalies, interpretation frequently
draws on other lines of evidence, including excavation results from similar sites, and data from other sources, including multiple geophysical techniques. Targeted intrusive investigation to ground-truth the results may be
used to test and augment the interpretation.
CUTTING-EDGE WORK
Current research and development in the use of geophysical techniques
in archaeology can be divided into three main areas: instrumentation and
field methodology; data processing and visualization; and archaeological
The Use of Geophysical Survey in Archaeology
7
applications. Not only are these developments enhancing how, where,
and why these methods are used, but also the increased availability of
instruments is allowing more archaeologists the opportunity to incorporate
geophysical prospection into their investigations. This section draws on
recent publications by Gaffney (2008) and Conyers and Leckebusch (2010),
as well as articles appearing in journals such as Archaeological Prospection,
Archaeometry, and the newsletter of the International Society for Archaeological Prospection (see http://www.archprospection.org/newsletters).
INSTRUMENTATION AND FIELD METHODOLOGY
Many developments have taken place in geophysical instrumentation and
data collection strategies in recent years, particularly improvements in
instrument sensitivity and the ability to efficiently collect much denser data
sets than was previously possible. Such progress is enhancing both the
quantity and quality of data so that not only can more detailed maps be
obtained, but also it is now possible to confidently identify a greater number
of buried features than just a decade ago. A few specific advances in the
major techniques are described here, although this is far from exhaustive.
The most notable developments in magnetometers have been that of
increased sensitivity and the combining of multiple sensors within a single
system. High sensitivity magnetometers, (e.g., alkali-vapor instruments and
even more sensitive superconducting quantum interference device (SQUID)
magnetometers), have the potential to detect very subtle magnetic anomalies
associated with features such as small post holes and palisade trenches (e.g.,
David et al., 2004; Linford et al., 2007; Neubauer & Eder-Hinterleitner,
1997; Schultze et al., 2007; Sheng, Li, Dural, & Romalis, 2013). Although
the possibility for detecting smaller and deeper features is exciting, the full
potential of these increased sensitivity devices is only reached in conditions
where the background soil noise is low, such as on deep, homogeneous loess
soils, otherwise their benefits are lost.
Magnetometer sensors of various types are frequently being combined to
produce multi-sensor arrays that can be mounted on a cart or sled, and either
pushed by hand or towed by vehicle. By incorporating real-time kinematic
GPS, and even inertial systems to correct for any offset of the GPS due to the
cart tilting, it is possible to collect a high density of measurements with excellent spatial accuracy. Not only can large areas of ground be covered without
the need to set out a survey grid, (around 1 hectare per hour with some systems), but also the incorporated GPS simultaneously provides a topographic
map of the survey area (Aspinall, Gaffney, and Conyers, 2008, pp. 181–184;
Gaffney, Gaffney, Cuttler, & Yorston, 2008; Schultze et al., 2008; Ullrich et al.,
2011).
8
EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES
In many regions, MS has traditionally been used in archaeological prospection as a reconnaissance tool or to help explain magnetometry results. However, as Dalan (2008) has demonstrated, this method has many significant
applications, including helping to understand the formation of features, sites
and landscapes, and identifying changes in land use over time. Dalan has also
developed down-hole MS sensors for the investigation of vertical variations
in magnetic properties, thereby enhancing the investigation of sites and features with complex stratigraphy, such as mounds (2006, 2008). Down-hole
MS measurements require 1 inch holes to be cored across an area and so is
more invasive than other methods, but this approach is minimal, cost effective, and can greatly enhance our understanding of vertical relationships.
In archaeological investigations, area earth resistance surveys have largely
been dominated by the twin-probe array, a specific configuration of the two
current and two potential electrodes (Aspinall & Lynam, 1970; Gaffney &
Gater, 2003; Schmidt, 2013; Somers, 2006); this is primarily for reasons of
speed and simplification of anomaly response compared with other configurations. In recent years, research with alternative arrays has demonstrated
that they may be better suited to particular situations, not least for their
use on cart systems where spiked wheels are employed as electrodes (e.g.,
Aspinall & Gaffney, 2001; Aspinall & Saunders, 2005; Dabas et al., 1994;
Schmidt, 2013; Walker et al., 2005). Such systems are opening up this method
to much larger survey areas, but require relatively flat, obstacle free areas
and, in the case of towed systems, locations where vehicles may be driven
across.
Investigations of vertical sections through the ground using resistivity
measurements are generally applied to specific questions about previously
known sites. Although still relatively uncommon in archaeology, this
approach has particular benefits over deeply buried and deeply stratified
sites such as settlement mounds and burial mounds where other methods
may be of limited use. Such an approach requires a dense network of
electrodes for data collection, followed by complex processing to topographically correct the data prior to inversion to allow the anomalies to be
visualized and then interpreted (Berge & Drahor, 2007, in Gaffney, 2008;
Schmidt, 2013).
GPR has changed dramatically in recent years, largely due to increases
in computing power and the development of dedicated processing software packages that allow visualization in different ways. The most
recent advances are occurring in instrumentation with the production of
multi-channel GPR systems. These combine multiple antennas and achieve
very dense spatial sampling, beyond what is practically possible by collecting many closely spaced traverses using traditional systems (Neubauer et al.,
2014; Novo, Dabas & Morelli, 2012; Trinks et al., 2010). The close spacing of
The Use of Geophysical Survey in Archaeology
9
multiple antennas, (i.e., <0.1 m), allows fractions of the wavelength to be
sampled, thereby producing true 3D data sets and consequently significantly
improve identification and interpretation of buried features. When mounted
on a vehicle and linked to a GPS, these new multi-antenna arrays can cover
around one hectare in a day.
GPR surveys frequently require detailed elevation measurements to
allow topographic correction of the data; for example, to allow horizontal
time-slices to be produced over features such as burial mounds (e.g., Goodman, Nishimura, & Rogers, 1995). Tilt correction is also being employed to
take into account the angle at which energy is being transmitted into the
ground on nonflat surfaces (Goodman, Nishimura, Hongo, & Niriaki, 2006).
As Gaffney (2008) noted, there is a need for more research in with EM
devices to better understand the complex relationship between instrumentation variables and the anomalies produced by archaeological features.
Recent papers reporting on new equipment address this and demonstrate
clear potential with these methods in many environments (e.g., Simpson
et al., 2009; Thiesson et al., 2009). It is expected that their use will become
more commonplace as more results are published.
The benefits of integrating all types of geophysical data with real-time
GPS are becoming more apparent. Not only is this an attractive option by
allowing workers to break free from pre-gridded survey areas and speed
up data collection, but it also assists integration of the results with many
other forms of data. Such an approach is not always possible (e.g., under
dense tree canopies), or may be too costly. While gridded surveys are more
time-consuming, they do ensure even coverage and sampling across an area,
although there are solutions to this.
Geophysical data are frequently shown to be more informative when multiple techniques are employed (e.g., Hesse, 1999). The solution to repeating
coverage of the same area with different methods is to combine many instruments on a single towed platform (e.g., Hill, Grossey, & Leech, 2004). Such
systems allow for even more rapid survey and survey at higher resolutions
than have been practical to date, as well as improvements in data fusion and
interpretation.
DATA PROCESSING, ANALYSIS AND VISUALIZATION
Over the last decade or so, there has been little change in the way that the
digital data sets from magnetometry and resistance have been processed.
GPR processing has seen more significant changes as computing power has
increased, first permitting the production of time-slices and today facilitating
real-time processing. Other areas of ongoing research in GPR data analysis
relate to the challenges of precise depth estimation (e.g. Leckebusch, 2007),
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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES
and improving data interpretation (e.g. Bönige & Tronicke, 2010; Leckebusch,
Weibel, & Buhler, 2008; Schmidt & Tsetskhladze, 2013).
As surveys are conducted at increasing resolutions and data-sets grow,
this is accompanied by an exponential rise in computing demands for
processing and visualization. Smaller, gridded areas can be processed block
by block, but the increased use of cart and multichannel GPR systems
produce very large datasets that are more efficiently dealt with as a whole,
and such an approach requires levels of processing power available on
“super-computers.” The management and archiving of increasingly large
datasets is also crucially important in a discipline where the vast majority of
geophysical data, interpretations and reports are digital. Advice on methods
for depositing and preserving such data are provided by Schmidt and
Ernenwein (2011).
Data fusion and visualization, especially from integrated multiple techniques, is another area of development. The use of GIS for both display and
analysis of geophysical data has advanced the integration of these methods
in archaeological investigation and assists interpretation. While simply overlaying maps of different data can provide a useful method of comparison,
the benefits of enhanced visualization and interpretation that are possible
when statistical approaches are employed to combine data from multiple
sources have been clearly demonstrated (e.g., Ernenwein, 2009; Kvamme,
2006b; Kvamme, 2006a; Neubauer & Eder-Hinterleitner, 1997; Watters, 2006).
APPLICATIONS OF GEOPHYSICAL DATA TO ARCHAEOLOGY AND ANTHROPOLOGY
Alongside new developments in hardware, software, and visualization, there
have been a number of exciting advances in the applications of geophysical
methods in archaeology. Recent papers highlight how geophysical survey
methods are uniquely placed to test archaeological and anthropological
hypotheses that might not be answered using traditional archaeological
methods (e.g., Conyers & Leckebusch, 2010; Horsley et al., 2014; Kvamme,
2003; Thompson et al., 2011). Large scale surveys conducted across entire
buried cities (see Gaffney et al., 2000, and examples in Johnson & Millet,
2013), and landscapes (e.g., Kvamme, 2003; Powlesland et al., 2006), have
utilized these methods to map and characterize buried archaeological
remains across huge areas without—or with limited—excavation. This is
allowing entire sites to be investigated and placed in the context of their
natural and cultural landscapes. It is now possible to study aspects such
as site size, content, structure and organization, and variations in these
across landscapes and regions. Thompson et al. (2011) have used geophysical
methods to investigate so-called persistent places, employing these methods
to study the use of space and landscapes, and changes over time. Their
The Use of Geophysical Survey in Archaeology
11
approach, which they term inquiry-based archaeogeophysics, is driven by
specific research questions that these techniques are well placed to answer.
Recent work also illustrates how geophysical data are beginning to be
employed in far wider areas of archaeological research; examples include:
site prediction (e.g., Conyers, et al., 2008); and to assist with population
estimates (Barrier & Horsley, 2014).
Horsley et al. (2014) demonstrate how geophysical prospection methods
also have a role in helping to define new hypotheses and research questions
about sites. As the cited examples above illustrate, large scale geophysical
survey can significantly alter the understanding of a site by providing a more
complete picture of a site’s extent, use of space, and so on, as well as potentially revealing new and unexpected details. Conducting such a survey at
the onset of an archaeological investigation therefore assists in the creation
of new, site-specific research agendas. As these are addressed through excavation, ongoing collaboration between geophysicist and archaeologist both
informs and enhances the results of both data sets through feedback.
CONCLUSION
As archaeological geophysics becomes more routinely practiced on all
continents, the full potential of these noninvasive methods will continue
to expand. While it is likely that the major techniques described here will
continue to dominate archaeological surveys in the future, technological
developments in such areas as instrument sensitivity and multi-sensor
arrays will undoubtedly carry on into the future. The effectiveness of these
techniques for investigating large areas and assessing many aspects of the
use of space and will significantly change the way archaeology is practiced
in many geographic and research areas. Geophysical survey is just one
tool available to archaeologists, and integration with various other complementary data sets, especially from remote sensing, looks set to continue to
develop and improve our understanding of the past.
Interpretation of geophysical data remains of key importance, and while
higher densities of data collection from multiple instruments should improve
this step, the huge quantities of digital data bring with them their own challenges in management and presentation as meaningful archaeological information. As Neubauer et al. (2014) note, tools need to be developed to help
communication between prospection experts and archaeologists, but also for
data archiving and long-term maintenance. As geophysical methods become
better established around the world and more practitioners become familiar
with the types of information obtainable with these methods, it is how these
data are used to inform, enhance, and drive research agendas that are perhaps
the area with greatest impact in archaeological and anthropological research.
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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES
Surveys will continue to be most effective when undertaken by workers who
have a strong foundation in archaeological deposits and their associated geophysical anomalies, and who are experienced in the collection of such data.
While training and practical experience therefore remain an important part of
a successful outcome, collaborations are revealing how the data from these
techniques can be used to help answer archaeological and anthropological
questions far removed from simply locating features worthy of excavation.
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TIMOTHY J. HORSLEY SHORT BIOGRAPHY
Timothy J. Horsley has more than 17 years’ experience utilizing geophysical
prospection techniques at archaeological sites in many parts of the world. He
holds an MSc and PhD in Archaeological Prospection from the Department
of Archaeological Sciences, University of Bradford, UK, and has taught at
graduate and postgraduate levels in the United Kingdom and United States.
His PhD research took him to Iceland where he developed his specialism for
applying geophysical methods in challenging environmental conditions. He
has since collaborated on research projects throughout Europe, the Middle
East, Asia, and North and South America. Recent projects using geophysical
data range from mapping Bronze Age field systems in Greece, to searching
for fortifications from the War of 1812 in Baltimore, USA, to producing
population estimates for Mississippian settlements in the American Bottom.
Tim is a currently an Adjunct Assistant Professor at Northern Illinois
University and also runs his own business providing surveys, training and
consultancy to the public and private sectors.
The Use of Geophysical Survey in Archaeology
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