How Archaeologists Know Where To Dig

How do archaeologists know where to dig? It’s a common question we get. In this post, you will find the YouTube video explaining how we decide where to dig and a full video transcript (with relevant references and links).

YouTube Video

YouTube Video Transcript

Here, you will find the complete transcript of the video in the previous section with hyperlinked references/citations.

Introduction

 [00:00:00] One of the most common questions archeologists get is how do you know where to dig? It’s a really great question, and the answer might surprise you. Usually, we target archeological sites to dig, but there are exceptions to that, which I’ll explain later. Hi, I’m Dr. Smiti Nathan, and I’m an archaeologist.

In this video, we’re going to explore how archaeologists know where to dig, so let’s get into it.

Local Knowledge

Generally, archaeologists want to dig archaeological sites, and a big part of knowing where to dig is knowing where archaeological sites are located. To find archaeological site locations, we use a few different methods.

Sometimes when we’re working in an area, locals tell us about places their elders might have told them about or there might be town lore about ancient settlements nearby. Sometimes this local knowledge can be really accurate and useful when trying to find archaeological sites. So one of the oldest ways archeologists located sites was through talking to people.

Now local knowledge has been a big part of my field work.

In 2013, we were conducting archaeological survey in Oman, and we were introduced to two elderly Omani brothers who told us there were  a lot of [00:01:00] old places in the Wadi Valley behind their house.

The brothers wanted to make sure that these areas and places were not forgotten, so they contacted the local office of the Ministry of Heritage and Tourism, and that’s how we eventually met the brothers.

Turns out there was a super important site in that area.

It actually turned out to be the first known example in Arabia of a production site for this super important material known as soft stone and I’ll link more information if you want to learn more about soft stone and the discovery process of finding that site and its importance.

This is just one example of how local knowledge has helped us locate important archaeological sites. However, it’s important to note that local knowledge has been taken advantage of in the past.

This ranges from not acknowledging local knowledge and the contributions it plays to site discovery to straight-up stealing artifacts to move them to “safer locations.”

There are movements to integrate local knowledge into the fundamental design of archaeological work, and building trust is key to that.

It’s a work in progress.

Archival and Historical Records

Now, archival and historical records may also contain [00:02:00] clues about the locations of archaeological sites, especially old maps.

A team of archaeologists in New Orleans, Louisiana, and the U.S. used old maps to identify potential archaeological sites. They did this by digitizing the historical maps and overlaying them on highly detailed modern images of the city. And this gave the archaeologists a unique reference for finding archaeological deposits.

Sometimes local knowledge or old maps might be hard to come by, so we turned to other techniques to help us locate archaeological sites.

Ground Survey

 One of the most common ways is the technique called ground survey.

 To conduct a ground survey, archaeologists just walk across an area and look on the ground for artifacts. And artifacts could be things like ceramics, glass, stone tools, or a plethora of other things. High concentrations of artifacts could signal an archaeological site might be underground or nearby.

Other clues like the remnants of stone walls or stone foundations may also directly indicate the presence of an archaeological site.

When archaeologists are designing a ground survey, we’re usually thinking about two things.

  1. The first is scale. So, how large of an [00:03:00] area do we want to cover?
  2. And the second is strategy. So, how do we want to go about surveying that area?

The answer to both these questions have an impact on what we might find and where we might eventually choose to dig.

Scale and strategy were crucial in my own research. Our team wanted to know if there were more unrecorded archaeological sites in northern Oman.

Since we had limited time and money, we made some key decisions.

In terms of scale, we decided to cover a hundred square kilometer area. And in terms of strategy, we decided to systematically survey a random 5 percent of that area. We were able to locate and record 52 sites in that random 5%. Of course, we made time to find sites through other methods, like talking to people, which led us to areas outside that random 5%.

Our ground survey helped us locate archaeological sites, some of which we decided to excavate.

If you’re interested in learning more about our survey work or ground surveys in general, I’ll have some information linked below.

Additional Ground Survey Reference:

  • Molyneaux, B.L., 2005. Archaeological Survey, in Handbook of Archaeological Methods, eds. H.D.. Maschner & C. Chippindale. Lanham, MD: Altamira Press, 106–32.
  • Ted Banning’s Archaeology Survey video

Remote Sensing

Another method of finding sites is through a technique called remote sensing. 

Remote sensing encompasses multiple different methods and technologies, typically relying on some [00:04:00] kind of device to capture data about what’s going on, on or under the ground.

These methods provide a way for archeologists to peek into or on the ground without digging, and it’s a useful way of finding sites without disturbing them.

GPR

One of the most commonly used remote sensing techniques is called Ground Penetrating Radar, or GPR. 

GPR works by using a machine that looks kind of like a lawnmower to send pulses or energy into the ground. These pulses pass right through non solid material, like sand, but reflect back up when they encounter solid objects, like rocks or bricks, which are referred to as anomalies.

The reflection patterns create highly detailed maps showing where those anomalies are in the ground. Now, if the GPR shows anomalies in a particular shape, like a rectangle, that could be an indication of something like a buried house foundation.

For example, at an ancient Roman site in northeastern Italy,  archaeologists have used GPR as a noninvasive way to map a 3,000-year-old harbor. Using the GPR data, these researchers decided where to conduct excavations based on the most promising areas they [00:05:00] identified.

Magnetometry

Another remote sensing technique is magnetometry.

 Using magnetometry, archaeologists can detect materials containing iron. If this sounds like metal detecting to you, there is a difference. Magnetometry is different from metal detecting because it only detects ferrous materials or materials containing iron.

A magnetometer can detect subtle differences in the composition of features as compared to the surrounding soil. So this means that magnetometers can detect archaeological features like ditches, herds, or pits. Basically places where humans have changed the soil chemistry in some way, for example by lighting a fire.

Like GPR, magnetometry produces maps showing potential anomalies.

I personally have a warm place in my heart for magnetometry because it was the first remote sensing technique I learned at my first field school in Hungary. On that project helped identify potential ancient houses, which excavation later helped confirm.

Zooming Out

This idea of examining an area using ground survey or devices like magnetometers and GPRs, this mental model can also be [00:06:00] applied to other things like images taken from airplanes, helicopters, drones, or satellites to see patterns on or in the ground that could indicate an archaeological site is present. This can be a really useful method because zooming out a bit, like a few hundred feet in the air, can help us see patterns from a different perspective.

LIDAR

 LIDAR, which is an acronym for Light Detection and Ranging, is a nondestructive, zoomed out way to help us find archaeological sites.

This technology uses a similar premise to GPR, but from the air.

LIDAR uses laser beams to create super detailed topographical maps. Using these maps, archaeologists can find unique features th at may indicate the presence of the site. LiDAR is popular in areas with thick forests or jungles because the lasers can beam right throug h the vegetation and reveal the ground below.

LiDAR has been used by archaeologists across the world. 

For example, in Northwest Cambodia, archaeologists use LiDAR map the sprawling medieval city of Angkor and discovered previously unknown temple complexes. My friend Ioana has also used LiDAR when [00:07:00] working on a project at the UNESCO World Heritage Site of Nan Modal, which is the largest archaeological site in Micronesia. Here, LiDAR helped reveal the remains of a huge cultivation system that supported feeding people as well as cultural and economic practices. 

LIDAR has also been extensively used in Central America to document Maya. In fact, LiDAR helped archaeologists discover the 3,000-year-old Aguada Fenix site in Tabasco, Mexico, which is the oldest known Maya city. The archaeologist who discovered the site actually did so accidentally. He was looking at LIDAR data collected by the Mexican government and noticed an anomaly, which turned out to be the Aguada Fenix site.

When it comes to remote sensing, we’re actually using a lot more automated detection analyses to help us locate archaeological sites. This means that in addition to poring over images ourselves, we’re doing things like programming codes, implementing deep learning techniques, and of course, harnessing AI. All of this helps us analyze and detect archaeological sites from these images.

This enables us to find more sites, which gives us more potential [00:08:00] places that we could possibly dig at.

Salvage Archaeology

Remember in the video when I mentioned, “Usually we target archeological sites to dig, but there are exceptions to that, which I’ll explain later.”

Archaeologists may excavate areas that are facing a potential threat, and this is often referred to as salvage archaeology. In the United States, construction companies are legally obligated to hire cultural resource management, or CRM archaeologists, to conduct excavations before the construction of a building to see if there are any sites that will be damaged.

Many countries across the world have similar heritage protection legislation, and conduct salvage archaeology projects.

In U. S. National Parks, archaeologists frequently conduct salvage archaeology projects. For example, at Chaco Canyon National Historical Park, archaeologists have recovered dozens of sites as part of salvage excavations. Some of these sites are up to 8,000 years old and contain over 15,000 artifacts.

Archaeologists may also excavate areas and sites that have been damaged or are at risk of being damaged. This could be due to climate and weather events like flooding, erosion, or even landslides.

For example, in 2017, a team of researchers affiliated with the Society [00:09:00] of Black archeologists conducted surveys to assess damage to African diaspora sites across the island of St. Croix in the wake of hurricanes, Irma and Maria. As part of this project, these archeologists established standardized measures to assess damage to sites after natural disasters.

In salvage archaeology, archaeologists often conduct smaller scale excavations like shovel tests or test units.

The goal here is to take a small peek underground to see if there is a site present and if it warrants further excavation.

This technique of test excavations isn’t limited to salvage archaeology, and actually other archaeological projects like academic archaeological projects might employ this technique too.

Outro

So how do archaeologists know where to dig? Well, as we’ve learned, there are a lot of answers to that question. Generally, we’re digging at archaeological sites and no matter what, we want to find out as much as we can about an area or site before we actually start excavating.

Sometimes archaeologists spent years gathering data through many different methods before [00:10:00] deciding eventually where to dig.

In other cases, archaeologists are told where to dig to see if there’s an archaeological site present.

 Sometimes we might, sometimes we must immediately excavate a site to prevent it from being destroyed or just to capture as much information we can before it’s lost.

Something to keep in mind is that even if an archaeologist locates an archaeological site, we may decide not to excavate it. Excavation is inherently destructive. Once you dig an area, you can never go back and re-excavate the same spot. Also, it costs time, money, and energy to dig. Because of this, archeologists have to be really careful, and we have to make sure we’re excavating according to scientific and ethical standards.

Now, if you’re interested in learning more about some of the things that we dig up, check out this video here on one of the most prevalent archeological artifacts.

Thank you for joining me, and I’ll see in the next one. Bye.

Additional References

How do archaeologists know where to dig?

How Archaeologists Know Where to Dig | Discover Magazine

How Do Archeologists Work? (U.S. National Park Service) 

How do archaeologists find sites? | Bone Broke 

Credits

Anya Gruber: Co-Producer, Researcher, Scriptwriter

Noor Hanania: Lead Video Editor

Smiti Nathan: Director, Co-Producer, Support Video Editor

Ioana A. Dumitru and Michael Harrower consulted on certain aspects of this video.


If you enjoyed this post, check out my channel and other videos.

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Smiti Nathan

I’m an archaeologist that travels around the world for both work and pleasure. I have a penchant for exploring ancient and modern places and the people, plants, and foods entangled in them. I write about archaeology, travel, and productivity.

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