Technology for Archaeology: Latest Updates to the Explorer's Toolbox

When Dr. John (Jock) McAndrews (a botanist and geologist by training) tried to prove the theory that a comet crashed into North America 12,900 years ago, changing the lifestyle of humans forever, he didn’t reach for a trowel. The senior curator emeritus, at the Royal Ontario Museum, recruited a team of students and set out to examine every mastodon tusk he could find. He was looking for evidence, underneath the microscope, that comet debris had splashed extra-terrestrial debris on these creatures. As Heritage Key reported in September, he found two mastodon tusks that have evidence of this.

Dr. McAndrews story is no longer atypical. Archaeology has become a multi-disciplinary activity that uses a bewildering away of technologies. Botanists analyze plant remains at ancient sites, physical anthropologists use CSI-like techniques to examine human remains and physicists use geophysical methods to examine archaeological sites before they are even dug up. Virtual Reality is of growing importance. Archaeologists - and Heritage Key - are using the tool to reconstruct ancient sites to help us understand the ancient world.

The array of technologies, and related specialists, being used to study the ancient past is immense. I doubt very much that any writer could list all the techniques being used today in a single article - there are just so many. In this article I’m going to try to give you an overview of some of the most popular techniques, along with lots of related links to explore.

Peering under the Ground: GPR, Electrical Resistivity Survey, Metal Detecting and Gradiometer survey

There are a wide-range of technologies that allow archaeologists to study a site without even digging it up.

Ground Penetrating Radar is a popular one. It uses radio waves to map out a picture the structures, and layers of soil, beneath the surface. Using this technology a team of technical experts and archaeologists can even construct a rough 3-D image. 

GPR is a popular way to examine burial mounds in North America,  where ethical considerations and legislation prevent archaeologists from digging. At Fort McCoy, a military base, GPR was employed to determine if several mounds on the site contained actual burials (It appears doubtful that they actually do).

Another method is electrical resistivity survey. It’s a relatively cheap method that measures the resistance to electric current of different layers in the ground. Archaeological remains may have lower or higher resistance than the soil around them. This will allow the remains to be picked up.

At Fort York, in Toronto Canada, University of Toronto archaeologists used it to search for structures, such as fortification walls, underneath the present-day fort. I used it myself on one such exercise and we were able to detect historic period structures without putting a shovel in the ground.

Metal detectors are commonly used to find metal treasures such as coin hoards. That being said this method doesn’t tell you much about a site, except that there is metal underneath a certain spot. 

A more informative method is Gradiometer survey. This method uses two magnetic sensors (magnetometers), to detect anomalies in the magnetic field of the surrounding area. This may indicate the presence of magnetized material, such as iron. These were used at Gallinazo Group to search for archaeological remains.

Getting a Birds-eye View: Google, NASA and LANDSAT Images

Even in the days before satellite photos archaeologists recognized the value of getting a birds-eye view of their site. They would hire planes to take aerial photographs, as at Nazca, or borrow aerial photos shot for other purposes (eg, for military recon).

If they were unable to get any photos they may also have tried climbing a hill or even putting a ladder beside a truck. Anything just to get a birds-eye perspective of a site.

Today archaeologists have much more choice. Google Earth provides free satellite photographs. The lower resolution shots are generally not too useful for archaeology, but the higher res ones are. In Afghanistan, an area that is off-limits to western archaeologists for safety reasons, researchers can detect sites by looking over this free satellite data.

Google Earth isn`t the only source of data. Private companies still offer satellite data (usually for a fee), and NASA produces numerous satellite shots that are useful for archaeologists. These satellite shots can often be customized to look for specific things. For example, LANDSAT photos can be used to look for water sources that may have been used in ancient times. Archaeologists Sarah Parcak and Gregory Mumford used them to search for archaeological sites in the Sinai desert.

Mapping out a Site: GIS and GPS

Once upon a time maps were produced entirely by hand. Archaeologists would have to note, in painstaking detail, the features on a site, its location, and the adjacent topography.

Some of these maps, despite the absence of computer technology, were extraordinarily detailed, a testament to the now dying art of hand-drawn cartography. Others, like a 1950 map of Gallinazo Group, are “sketchy” and need to be re-drawn using modern techniques.

Today GIS has become the main tool with which sites are mapped. Artefacts, structures and topographic information can all be entered into a computer database. This database can then be turned into a highly detailed map, with which archaeologists can conduct a wide range of analysis.

For example, an archaeologist can tell where people were living in different time-frames, by comparing artefacts to the structures on site. They can then take information and compare this to the natural resources available and the landscape, and figure out how people were surviving.

The Tell Madaba project made early use of this technology. They turned a 1993 surface survey of the modern day city into a map showing where pottery sherds were found. 

GPS (Global Positioning System) is another technology that is being used. It uses satellites to triangulate exact positions. Modern day versions are accurate to within a few meters. At Gallinazo Group, on the North Coast of Peru, researchers have been using the technology to create a detailed 3D map of the site. One of the mounds, V-59 (also known as Huaca Gallinazo) can be seen in the photo above.

Virtual Reality

Virtual Reality is emerging as a powerful tool in archaeological research and education. Heritage Key is home to King Tut Virtual, a site where you can walk around Tutankhamen’s simulated tomb and interact with others, and Stonehenge Virtual, in which you can visit the ancient site at different eras of its construction.

When being used for archaeological research, it's imperative that the models must be completely true to the archaeological data, which is harder than it looks.

When archaeologists and technicians create models, such as Virtual Qumran, they will agree on where certain features are. But there may be other aspects of a site that they don’t agree on (eg, how high does this wall go?)

VR allows archaeologists to test out different ideas. Dr. Robert Cargill used a series of 'data switches' to try out different ideas of what Qumran really looked like. By comparing the various interpretations virtually, archaeologists can come up with the one that is most likely. They can also ferret out interpretations that are not physically possible (eg, a wall can't go up this high because it would fall down).

3D Photography and Lasers: Scanning and LiDAR Scanning

It’s easy to take for granted the importance of photography when it comes to archaeology. A solid photographer, with good photographic equipment, can give you a detailed and stunning look at ancient artefacts. Just take a look at Sandro Vannini’s work on Heritage Key, or the thousands of amazing shots in our Flickr group.

3-D photography is a growing field (again check out more of Vannini’s work). It gives archaeologists and the general public a very detailed look at an artefact. The Royal Ontario Museum, in Toronto Canada, has 3-D images of several items from their collection.

Laser scanning is another emerging technology. A laser system, operated by a highly trained team, will take thousands of measurements of an ancient structure. Each measurement will have the exact location (relative to the other measurements), allowing for a very exact model of an ancient structure to be created.

The Scottish 10 project aims to create laser models of Scottish sites, including Antonine Wall and New Lanark, and researchers painstakingly mapped the catacombs of ancient Rome using 3D scanning techniques. Another example is a reconstruction of the Mayan site of Tikal. A photo from this project can be seen above.

LiDAR scanning is an airbourne technique that has been used by researchers trying to penetrate deep forest or jungle to map, for example, Maya structures in Belize, and has also been used in Giza.

Examining Human Remains: Stable Carbon Isotope, Forensic and DNA Analysis

The range of techniques that can now be used to analyze human remains is bewildering. Stable carbon isotope analysis is one such method. It looks at the different levels of carbon in the bone to determine what kind of diet a person was eating before they died.

At the site of Leptiminus, in Tunisia, researchers used this analysis to determine what people were eating at this site during Roman times. They found that they loved their Grouper, a kind of fish. On the other hand they didn’t eat much of the local fish sauce, despite the fact that the people were producing it for export!

Aside from determining what people eat, it’s also possible, using forensic techniques, to determine what diseases or medical conditions they had, such as Leprosy. Lesions on a person’s skulls, as well as teeth loss, have been used to diagnose ancient lepers.

DNA analysis is becoming increasingly popular. Mitochondrial DNA (from the mother), and Y DNA (from the father) has been used to plot out ancient migration patterns. Mutations occur in this DNA over time allowing scientists to chart when population movements took place. 

Another use of DNA analysis is in putting together lineages and, along with forensic techniques, this technique was put to full use in the investigation into the death of King Tut. 

Dating the Finds: C-14, Tree Rings and Thermoluminescence

Absolute dating has been an essential part of archaeology for nearly 50 years.

Carbon-14 dating was developed in the 1950s by a team led by Willard Libby, who would later go on to win the Nobel Prize in Chemistry for his work.

C-14 is found in organic matter, and it decays, with a half-life of about 5,730 years. Archaeologists can measure the amount of this substance left in an object and use it to get an approximate date.  This sounds simple, but each date must be calibrated because the amount of carbon-14 in the atmosphere varies by year.

The technique has been used to study human coprolites (faeces) and to re-date our earliest human ancestors.

Which brings us to tree ring dating – arguably the earliest absolute dating method used. Tree rings grow as long as the tree is alive. During times of robust growth the rings will be larger (wet, good years). On the other hand, during times of stress (dry, poor years) there will be little growth.

The rings are organic, which means they can be carbon dated. Scientists can compare the date of the rings (by counting back) to the carbon in the measurements, to figure out how much C-14 was in the atmosphere at a particular time. This can be used to calibrate C-14 dates.

On some archaeological sites, where trees trunks are used for poles, or where tree rings are found in the same context as structures or artefacts, the rings can be used as a dating method in itself. You can count the rings back to the correct time.

Tree ring dates are also useful for climate reconstruction. For example a team of scientists working in New Mexico were able to correlate a period of poor tree growth (ca. 300-500 AD) with a period when the Anasazi population, in the Four Corners area of the southwest, was declining.

Another absolute dating method is Thermoluminescence. It is commonly used to date ceramic remains such as pots. All matter is bombarded by radiation on a regular basis, but when ceramics are fired, this energy is released, and then starts to build up again. Scientists can calculate the rate at which this energy is building up and use this to extrapolate a firing date for the pottery.

Analyzing Ceramics: Computer Assisted Grafting, GIS, X-ray Diffraction, Thin Slide Analysis and Raman Spectometry

You can learn a lot about a culture by looking at its pottery. For starters most cultures produce it en masse, since it’s needed to store material. Also it tends to survive well on sites.

In areas that had a large ancient settlement, an archaeologist, without digging, can literally walk across the terrain and find pottery remains on the ground.

Changes in the decoration on pots can tell us how culture is changing (are new people moving into a site?), foreign relations (where are these pieces from?), subsistence (are people are adopting a sedentary lifestyle?) and many other things. Analyzing ceramics is an important part of archaeological procedure and, as such, a range of technologies has popped up to help.

Believe it or not the first step archaeologists often take, when it comes to analyzing pottery, is to draw it by hand. Most archaeologists receive training in how to draw a pottery piece. It’s much cheaper than taking 3D photographs of all of them and many archaeologists will tell you that the drawing process forces them to examine, in pain-staking detail, the shape and decoration of their finds.

The high-tech part comes in after the sherds are drawn. Computer Assisted Drafting programs are often used to digitize these drawings, which in turn can be entered into a database. These can then be displayed on a GIS system.

At Tayinat, in southeast Turkey, pottery remains indicate that, around 1200 BC, a group of settlers came to the site from the Aegean. The pots they used are similar to those found in the Mycenaean civilization, as Professor Tim Harrison told Heritage Key.

There are many other high-tech means of pottery analysis. X-Ray diffraction technology can be used to determine what minerals the pottery has. The pottery is powdered and mounted on a slide. It is then bombarded with x-rays.

The x-ray image will give an idea as to how much of the radiation went through the pot, allowing researchers to determine what minerals it contains. This information is valuable since it can tell archaeologists what materials the pottery was made from. Is it from a local source? Or from clay that is located far away?

Another way to look at pottery is through thin slide analysis. This technique uses a thin section of pottery, only 0.03 millimetres wide, which is put under a microscope that emits light. The slide is thin enough that a scientist can get a basic understanding of the minerals on the material.

Raman spectrometry is another method. It uses a laser beam to analyze the composition of an artefact. The beam hits the artefact, and a photon is reflected back. You can tell what substance you’re looking at by analyzing the energy level of the photon.

Digging Flora and Fauna: DNA, GIS and Cat Mummies

Plant and animal remains are invaluable in trying to reconstruct what happened in the past. They can tell us about the diet that ancient people were eating, what species were being domesticated and which ones were being driven to extinction.

They are many methods to analyze these remains. DNA tests can be used to determine how they are changing genetically. Mapping wise they can be plotted out using GIS. They can also be put under a microscope to determine how their shape and form is changing.

On the plant site, these techniques have been used to determine how agriculture spread to the Great Lakes area. Archaeologists know that maize went from the American Southwest to the American South and then “spread up the Mississippi,” (as University of Toronto archaeologist David Smith said) reaching New York State by 1 AD and Ontario by 500 AD.

They know that, as it went north, maize adapted to the colder environment. The spread of this plant paved the way for the development of full-scale farming, which appeared in the Lower Great Lakes (Erie, Ontario and Huron) by 1000 AD. This in turn paved the way for permanent settlements which grew larger and more complicated.

On the animal side, cat mummies have been analyzed to determine how they lived and died. Contrary to popular belief many cats faced a sad end, being sacrificed at a young age.

Of course, the Archaeologist's technological toolbox is always evolving, with new techniques emerging all the time. This makes it an exciting time for the discipline, with our understanding of the world being blown open as never before.

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