Home > Areas of Specialisation > Ground Penetrating Radar in Archaeology

Ground Penetrating Radar in Archaeology

By: Grahame Johnston - Updated: 7 Oct 2012 | comments*Discuss
Ground-penetrating Radar Gpr Excavation

Ground-penetrating radar (abbreviated as GPR) is a technique used in geophysics to collect and record information about the earth’s subsurface. Archaeologists have employed this technical procedure for many years and it is also common in other scientific fields such as geology, environmental studies, and even engineering.

Archaeological geophysics involves a manner of collecting data that permits the field archaeologist to learn about and map underlying archaeological features otherwise impossible to discern using traditional field methods. Archaeologists take advantage of the physical and chemical changes within the ground relative to the presence or absence of subterranean items. Using highly sensitive instruments the specialist technician can measure, map, and interpret the data signals, received by the GPR system, into useful information.

Purpose of Ground Penetrating Radar

Generated GPR maps provide primary data that is used to direct the establishment of excavation sites or to identify sensitive areas containing cultural remains, such as burial sites, that would be better left untouched and therefore the information can guide archaeologists to avoid disturbing these locations.

The greatest advantage of ground penetrating radar methods is that they gather an immense amount of information about the near-surface in a totally non-invasive, non-destructive way, permitting large sites with concealed remains to be viewed and analysed efficiently yet accurately, while also protecting and preserving them.

The GPR Technique

The ground-penetrating radar technique involves transmitting high frequency electromagnetic (EM) pulses from a surface sender into the ground. If the EM waves strike an object they will be bounced back to the surface. The time elapsed between the pulse being sent and it being received back will provide evidence of depth. The wave’s angle of reflectance from buried materials or soil changes in the ground is measured by GPR’s sensitive antenna and interpreted by the operator. This process is enhanced when hundreds of reflections are measured and recorded by antennas that are operated in a close criss-cross grid scheme to create a three-dimensional interpretation of the soil, sediment, and feature changes under the surface.

All sedimentary strata and buried artefacts in the ground have peculiar physical and chemical properties that influence the velocity of the EM energy spread, importantly, electrical conductivity and magnetic permeability. Differences or variations of the returned wave energy are indicative of underlying archaeological features such as architecture or artefacts. However, if the archaeological features are composed of near similar material as the matrix, or they have identical physical and chemical properties, then the lack of discernable variation will render the objects ‘invisible’ to GPR equipment.

While small EM sending antennas can be hand held and ‘walked’ across an archaeological site many larger units are usually placed directly on the ground and moved by being fitted onto a non-metallic sled arrangement and pulled in a long, straight line. Antennas that are located too high above the ground will not work effectively as their energy waves will fail to penetrate the ground, as most will be reflected back from the ground surface.

An Invaluable Exploratory Tool

Archaeologists can detect ancient roads, house floors, architectural features such as walls, midden, and wells; geophysical features such as riverbeds; and even smaller objects such as tools and other artefacts. Strong reflections produce distinct black bands on the display instruments, while moderate reflections produce grey bands. It may take a GPR archaeologist many years to become proficient at ‘decoding’ the recorded display information. Once perfected, the procedure of using ground-penetrating radar before or during archaeological excavation has proven to be an invaluable exploratory tool.

You might also like...
Share Your Story, Join the Discussion or Seek Advice..
Why not be the first to leave a comment for discussion, ask for advice or share your story...

If you'd like to ask a question one of our experts (workload permitting) or a helpful reader hopfully can help you... We also love comments and interesting stories

(never shown)
(never shown)
(never shown)
(never shown)
Enter word:
Latest Comments
  • praveen
    Re: Academic Qualifications to Be An Archaeologist
    Sir I am going to finish my BE degree in mechanical engineering.I like to study archeology. if it possible…
    30 November 2016
  • ArchaeologyExpert
    Re: Dating Techniques In Archaeology
    coprop - Your Question:I have a gold ring which I believe is ancient but also important!There are many factors why I think…
    23 November 2016
  • coprop
    Re: Dating Techniques In Archaeology
    I have a gold ring which I believe is ancient but also important! There are many factors why I think it's genuine! The way…
    22 November 2016
  • coprop
    Re: Being Aware of Fake Archaeological Artefacts
    Not all eBay rings and jewelery are fake! But there are still ways you can tell them apart! A genuine ring…
    21 November 2016
  • jackers
    Re: Pottery Experts
    Does anyone here know about muesum copy classical period 450 b.c pieces? Ive been told although a copy they can be very valuable. I can't find…
    21 November 2016
  • alkebulan
    Re: Academic Qualifications to Be An Archaeologist
    Im on the verge on applying for uni I want to persue a career in archeology, any recommendation before I do…
    19 November 2016
  • Dylan
    Re: The Bone Expert
    Hi I would really appreciate your help, I have found what I believe is a tooth that belonged to an animal in my dolmio sauce, they have…
    14 November 2016
  • ArchaeologyExpert
    Re: Be a Volunteer Archaeologist
    Aries - Your Question:Hello, I am currently working as a trainee in an Environmental Consultancy company for over a year now, I…
    4 November 2016
  • Aries
    Re: Be a Volunteer Archaeologist
    Hello, I am currently working as a trainee in an Environmental Consultancy company for over a year now, I graduated as BA…
    3 November 2016
  • James
    Re: Etched Vase: How to Discover its Origins?
    Respected Sir, What methods and techniques were available to date artifacts as well as ancient civilizations…
    30 October 2016
Further Reading...
Our Most Popular...
Add to my Yahoo!
Add to Google
Stumble this
Add to Twitter
Add To Facebook
RSS feed
You should seek independent professional advice before acting upon any information on the ArchaeologyExpert website. Please read our Disclaimer.