'Armchair archaeology' in Afghanistan: The possibilities and pitfalls

Lecture transcript

David Thomas, 9 May 2013

Adrienne Leith: Tonight we are in the second of our series. These lectures are co‑hosted by the University of Melbourne and Museum Victoria as part of the major Touring Hall exhibition. Tonight's lecture, called "Armchair Archaeology in Afghanistan," will be presented by Dr. David Thomas, and it would seem many of you already know him.

David read his undergraduate degree in archaeology and anthropology at Cambridge, and then completed a Master of Science in computing and archaeology at the University of Southampton. He undertook his research for his PhD entitled "The Ebb and Flow of an Empire" ‑‑ I think I'm going to mispronounce this ‑‑ "The Ghurid Polity of Central Afghanistan in the 12th and 13th Centuries" at La Trobe University.

In between those studies, David has held research appointments on several archaeological projects in the Near East, and has spent a total of over four years digging in what he calls exotic locations such as Libya, Syria, Turkmenistan, and Afghanistan. He has authored and contributed to numerous archaeological publications and is a bit of a media star. He's appeared on radio and television talking about his ASAGE project, which means Archaeological Sites of Afghanistan in Google Earth, which we're going to hear all about tonight.

David is an honorary research associate at La Trobe University and currently works for Ochre Imprints, which is a leading archaeological consultancy here in Melbourne. He says he has a tendency to stare at satellite images in his spare time. Please join me in welcoming Dr. David Thomas to the stage.

David Thomas: Thank you very much, Adrienne. In case my boss is here tonight, I don't do it during work hours.

A few years ago, I was interviewed by Red Symons for his "Breakfast" show on ABC Radio. One of the first questions he asked me was, "David, are you fat?" This might seem as quite a strange introduction, but not untypical of Red Symons. The reason he asked that was, we can do so much from our computers.

These days, we can shop online, we can watch movies and listen to music, and we can play virtual reality games. Here am I, seeming to do virtual archaeology. He was worried that we're getting detached from reality and that we're just becoming tied to our desks. The timing of his call was quite ironic because I was actually down a hole at the Old Melbourne Gaol, digging.

I guess I'd like to start off by reassuring you that I do still get my hands dirty. In fact, digging is the best part of my job. I get a real buzz from finding something that nobody else has seen for hundreds or thousands of years. But, as times and technology move forward, archaeologists need to be smarter about what we do.

First thing, digging is very destructive. It's also quite expensive. It generates huge amounts of information, sometimes not necessarily the right sort of information we're interested in. We need to be trying to find out as much as we can about archaeological sites before we actually stick a shovel in the ground. That's where the satellite images come in. It's one way of sussing out a place before you actually visit it.

The other thing that I'd like to reassure you is that I don't have an armchair. Hopefully, at the end of the talk tonight, you'll get a better understanding of what I do do when I look at satellite images. I'll go through a bit of the history of aerial archaeology, then I'll look at the four sites that form this magnificent exhibition. For that bit, I'll actually do a live demonstration using Google Earth. Fingers crossed, the gremlins behave.

After that, then I'll look at some of the other places in Afghanistan that I've both worked at and then studied using Google Earth and satellite imagery. The last one, the lost minaret of Sakhar is a bit of a scoop because that's only come to life in the last couple of weeks.

Even though archaeologists study the past, we like to think we're cutting edge, that we're using the latest technology and techniques. Very often, what we are doing has its basis in pioneering work decades and even hundreds of years ago.

One of the things that we use when we look at sites from above is different patterns of growth in vegetation. For example, if there's a buried wall, the soil on top of it will be thinner than other places, so the soil will dry out and the plants won't grow as well there compared to where there's a ditch or a pit, where the moisture can act as a reservoir. We look for so‑called crop marks.

This quote could have easily been written in the last decade, but what's interesting about it is, Monsieur Louvet was writing nearly 400 years ago. Nothing is new.

We need to turn the clock forward, though, for about 250 years before archaeologists started actually thinking of using aerial images. Part of the problem was the limited technology for getting up in the air. Although there was a plan to use balloons to photograph this site in India, it didn't happen.

Soon afterwards, people did start taking photographs, such as ones of monuments of Stonehenge in England, but it wasn't until World War I that aerial archaeology took off, so to speak. That was through the work of both Germans as well as British pilots and French pilots who were flying numerous sorties over Europe and particularly the Middle East.

The great advantage of looking at the Middle East from the air is, there's limited amount of vegetation and the preservation is generally quite good. Things tend to stick out of the desert. You have Flight Lieutenant Maitland, who published his work on the so‑called "works of the old men" of Arabia in 1927 in the very first issue of the journal "Antiquity." Even back then, people recognized the value of the technique.

Probably one of the greatest proponents of the discipline was Father Poidebard, a French priest who spent a couple of decades in the inter‑war years studying the Roman limes or the fortifications in the Middle East. That's Father Poidebard in the centre. This is one of the photographs that he took. This is a Roman castellum or fort out in northeastern Syria near Tell Brak. It's a beautiful image.

What's particularly useful is that when you compare it to the Google Earth image of the same place today, it's so much clearer. This partly because over the years, there's been a lot of agriculture activities in the area as population has grown and there's increasing pressure on archaeological sites and at Brak itself, the edges of the site have been nibbled away as farmers keep on encroaching. These old images are very useful for trying to delimit the sites in the past.

The technique is still used today. David Kennedy is in the University of Western Australia. He's flown all over western Jordan, taking thousands of photographs and discovering thousands and thousands of sites. Really important, really useful work.

Now, David's able to do this because he has very good relations with the Jordanian Air Force. It's more difficult to do this sort of survey, for example, in Israel or in Syria, where they're a bit more precious about national security. That's where satellite images start to come in, because, as the Americans and the Soviets realized quickly in the years of the Cold War after World War II, you don't need permission to photograph places if you're high enough up.

Particularly in the 1960s, 1970s, there was a whole series of American spy satellite images taken called the Corona series and others. I'll come back to them a little bit later. Into the 1980s, you get a few more legitimate sources of imagery such as QuickBird and Landsat. Landsat is freely available to anyone. QuickBird, you have to buy those.

The problem that this early satellite image we had was that (a) it was hard to get hold of, (b) it was expensive, and (c) you needed some pretty advanced expertise and equipment to manipulate the images. The reason that is, if you have a satellite directly above a place that is nice and flat, you get a relatively accurate photograph of what is on the ground. If you start taking oblique views from the side, particularly in mountainous terrain, it becomes a lot, lot harder. You really have to get ground control points that you know the precise coordinates of, and then twist and warp the satellite imagery.

These were major drawbacks for you and I and many archaeologists as well using satellite imagery, until about 2005, when Google Earth was launched. Google Earth is a virtual globe. It's like a mosaic or a patchwork of thousands and thousands of satellite images and high resolution aerial photographs that have been stitched together. Effectively, the boffins at Google Earth have done all the hard work for us, put the images in the right place, and away you go.

The great advantage of using Google Earth, as you'll see in a few minutes, is that it's very easy to use. Irwin Scollar as well as numerous other archaeologists recognized the importance of this development very, very quickly.

Here you can see the quite sort of stripy effect that having these images from many different sources has in the area. Google Earth is repeatedly updating its imagery, so today when you look at the Middle East, you'll find it's much more homogenous like this. They've used the same source of the satellite imagery taken on the same day, which has its advantages but also its disadvantages, as we'll see.

Google Earth has been phenomenally popular. As you can see, there are over a billion downloads in, what, eight years. It doesn't mean that a billion people have used it, of course. I think I've probably downloaded it about 20 times myself. But the general public has been able to use satellite imagery. This is reflected in the fact that there are 19,000 topics on the history bulletin board related to Google Earth, people who have just found something that they're interested in, or are sharing information with other people. There's a Scandinavian called Stefan Geens, who's described it as the democratization of satellite imagery.

Here we see Rome, where somebody has gone to great lengths of creating 3D reconstructions of the major buildings. If you click on each of these buildings, you'd pull up an image of the building and information about it. It's a fantastic educational resource as well as a great time waster.

The problems, though, are that in areas such as Merv in Turkmenistan, you have sometimes this mishmash of medium‑resolution and high‑resolution images. Here you can see the outline of Gyaur‑kala, which is a Bronze Age fortress, with the citadel here. That's very clear because these fortification walls are so huge, but there's very little detail in the middle.

Here to the west, Sultan Kala is much more detailed. You can just about see the fortification wall coming down through here in the low‑resolution image, but obviously, if you want to try and trace canals and roads, this is the sort of image you want to be dealing with. Unfortunately, with Google Earth, you're never quite sure when they're going to be updating imagery. That's one of the failings.

The pros: it's free. You can pay $400 for a pro version, which is useful for a few people, but most people don't really need it. All you need is a high‑speed Internet connection. It's pretty easy to use. It's uncensored. There are Google Earth images of Guantanamo Bay, which an archaeologist has used to chart the expansion of the facility. This is one of the Americans' forward bases that they set up in the desert before the invasion of Afghanistan.

When you generate data relating to Google Earth, it's in very, very small file sizes, so I can send it to anyone around the world. Even if they have a slower Internet connection, they will receive the information very easily.

It's also safe. This is a couple images from working in Jam in central Afghanistan. It's a bit of a trek to get there, and when you are there, you have to be careful.

What are the disadvantages? Well, only certain types of sites are visible. Obviously, major fortifications and the large occupation mounds are very easy to see. Scatters of artifacts, you won't see at all. It would be unrealistic to think that we're getting a full representation of all the archaeological sites in the area, but it's useful nonetheless.

As I said, you've got no control over when an image becomes available or gets taken down, and also the quality of the image. It's less precise and capable than the proper GIS software. GIS is geographical information system software. We'll have a look at that later and see what you can do.

Now we're going to go and try using Google Earth. One of the interesting things about Google Earth is, when people open it up for the first time, very often they look at where they are. We have a whole world to explore and we need the security blanket of seeing where we are.

This is where we are. Now we're going to fly to Afghanistan. If you get travel sick, you might want to avert your eyes for a minute. The great advantage is, there's no jetlag.

Here we can see some of the sites that we'll be talking about. First of all, you have the four sites in the north-east of Afghanistan that form part of the exhibition, and then later I'll be talking to you about the World Heritage Site of Jam in the centre of Afghanistan, down in the Registan Desert where we did ASAGE research, Lashkari Bazar and Sakhar.

First of all, let's go to the oldest site in the exhibition. That is Tepe Fullol. As you can see there, it's not actually listed as Tepe Fullol, but a different name, Khush Tepe. This highlights some of the problems. If you don't have precise information to start off with, there are limits to what you can do.

Fortunately, there is a gazetteer of archaeological sites in Afghanistan that we can refer to. This was compiled by an Australian called Warwick Ball in 1982. It lists 1,200 archaeological sites. This description for Tepe Fullol, or Khush Tepe, is that it's a confluence of two river valleys to the southeast of the town of Fullol.

This coordinate here is on the top of a mountain. Here you're seeing the problems that, if you don't have very precise coordinates ‑‑ obviously, people working in the 1980s had limits to the accuracy of their data ‑‑ it can give us problems when we're trying to identify sites. If we assume that the site is within a broad area around that, we can zoom in further. Tepe Fullol should be somewhere down there.

The trouble is that the site is a small site. It's only 14 by 18 metres high, I think. It's pretty much like looking for a needle in a haystack when you've got a mountainous landscape like that. I know from looking at Warwick's plans and his maps in the gazetteer that it's somewhere around here at the confluence of this river valley and this one, but I can't identify it in the satellite image.

What I can do, though, I can create a place mark and give it a name. I can move it to where I think it is, roughly somewhere down here. We have the coordinates ‑‑ the latitude and longitude. I can either note these down and email them to Warwick as an update to the data he has for his gazetteer, or I can just export this data as a KMZ file. That way we can share information.

The most important information we get from this site in particular is a sense of its place in the landscape. It's a very mountainous area. Obviously, the river valleys are important and probably why it was situated in that place.

Let's go to Ai Khanum and see if we can find out a bit more about that site. Ai Khanum, as you know, is one of the great classical cities of central Asia. Again, it's at the confluence of two major rivers. It's naturally a well-defended place.

If we go in a bit closer, you can see various dents in the landscape there. You can see this upper town here and the lower town here. If we go in even closer, we'll be able to see a bit more of what looks like a wall coming along here. To a certain extent, we're guessing at what's there. We don't need to, because there are plans of the site.

What we can do, if we simply go to Google and Google search for an Ai Khanum plan, it comes up with something like this. It would be really clever if we could put this on top of the satellite image. We can. If we go "Add image overlay," and we'll select. I saved it to the desktop earlier. There's our plan.

It's not quite where I want it to be and it's not at the right scale, but we can deal with that. Firstly, if we make it to transparent or more transparent, then that'll make it a lot easier to line it up with what's on the ground, so we'll make it about 50 percent transparent. Then we can spin it around like this, and we can start squeezing it to get it to the right scale. I can stretch it or squeeze it depending on what's appropriate. Now we'll start zooming in to try and get this a bit more accurate.

This is really an ideal site to practice on because you have such clear features with the high citadel and the walls. Now that we're getting it a bit closer to it in size, again, we can scale it. We can put it on top and rotate it around a bit more. We're starting to get it to the right size.

What's important about this is that once we do get it into the right size, we can start looking at the dents in the ground and making some more sense of them. Now when we zoom in, we can start to understand what we're seeing on the ground.

The centre of the site is the palace. It would be useful to mark that out. We're going to call this "palace" and start putting some dots there. I don't really want the centre of it to be obscured, so I'm going to make it outlined. I'll make the width, say, three. Now if I turn off the image, I can see that that's roughly in the right area. I can then edit that to define the edges of the palace a bit more accurately.

The reason this is useful is that Ai Khanum, like many other archaeological sites in Afghanistan, has been severely looted. If you look at this area down here, these pockmarks are the remains of robber holes. I've also got an image that I've linked to the site, which will give you a more graphic impression of the scale of the looting of the site. This isn't a couple of kids going in there with a sand bucket, this is on an industrial scale. That gives you a sense of the problems that cultural heritage management has in Afghanistan.

Here, looking obliquely, you also get a sense of the topography of this raised area in the lower town.

We'll now head to Tillya Tepe, which has some of the most spectacular finds. Tillya Tepe is a burial site, so we're not really expecting to find that much visible site in the satellite imagery. The original site dates to the Iron Age, and then the burials are later.

We can identify the site. We can also measure it by using the ruler. It tells us it's about 67 metres across. This is useful in the management of the archaeological remains and getting a sense of which period sites are bigger than others.

It's also useful to have a look at the surrounding area. This is where you spend hours and hours looking at satellite imagery. Close to Tillya Tepe is this thing here, which almost everyone would think, "That's not natural." You'd be right. It's actually a Hellenistic site called Emshi Tepe.

When you go in closer, you get a sense...You have these circular fortifications and then the town inside. Again, we can get a sense of how big it is by doing a quick measurement. We're looking at a site that's about 450-500 metres across. This is a big site dating back over 2,000 years. The reason I know it's Emshi Tepe is because I've looked up Warwick Ball's gazetteer and imported the data he has into Google Earth, which is quite easy to do.

Finally in this demonstration, we'll look at Begram. Begram, as many of you will know, is the site of an air base. There was actually a crash there last week. That's the air base and the fairly notorious prison associated with it. Fortunately, they haven't impacted upon the archaeological site, which is quite close up here. This is the one of the four sites that I have been to. We visited it in 2007.

The problem with Begram is that it was dug in the 1930s by the French. Since then, obviously, there's been a lot of overgrown vegetation on top. During the '80s and the '90s, it was a very strategic point in the war against the Soviets and then the civil war. What you see along here are foxholes and trenches that have been dug into the site when it was used a military base. When we visited the site, we pretty much had to stick to this path here because the rest of it is mined. That is a sobering thought when you're walking across the landscape.

What we weren't told when we were there is that there's actually another part to the site. We'll see why we weren't told about it in a minute. That's just up to the north. One of the great things about archaeological sites is that they were often built for strategic purposes. Those strategic values are still relevant today. Here you can see the mound at the crossing point close to the confluence of two rivers. This fortification in the past would have controlled access to the north and to the south.

When we start looking at older satellite imagery, we can use a very useful thing called the historic imagery. This allows us to flick through older images that have been put up back to 2004. You'll start to see that there are a few strange things going on on the top of the mound. When we go back a little bit earlier, those neatly arranged things are tanks.

This site has been used as military base. This is not uncommon at all in Afghanistan and elsewhere. It's one of the issues that we ran into when we were trying to do some fieldwork at Bala Hissar in Kabul in 2007 ‑‑ this conflict between issues of national security, strategy, and secrecy and archaeological sites.

Hopefully, that's given you a sense of what you can do with Google Earth. What have we been doing at other sites? Jam was Afghanistan's first World Heritage Site. I was lucky enough to work there in 2003 and 2005. One of the major reasons it was nominated was because of this magnificent minaret, which is over 65 metres high, and at the time was probably one of the tallest buildings of the world. It's beautifully decorated with turquoise tiles. The detail in the brickwork here includes verses from the Quran as well as geometric patterns.

Unfortunately, like Ai Khanum, these holes in the hillside behind the minaret are robber holes. The site was badly looted in the 1990s, in particular. One of the things we started to think about was, can we actually get a sense of how bad the looting's been? None of this information has been properly documented before. We can use this, hopefully, by combining satellite imagery and GPS coordinates.

We focused on a 50 metre wide part of the hillside, which stretches from the fortress down to the river. By walking up and down on very steep slopes, we discovered over 120 robber holes, amounting to at least 1,200 square metres of ground that had been destroyed. That's probably an underestimation because all the spoil from the robber holes is covering up other ones.

But the robber holes include important information. It showed that there are architectural remains in over 70 percent of them. They stretch all the way up the hillside. That gives us a sense that although the minaret looks as if it's isolated today, it was actually at the centre of a really important urban centre. We estimate, based on density of robber holes here and other looting that's gone on here, that there were at least 300 robber holes on this one side of the river.

I got thinking, what about further afield? By spending hours and hours staring at the high resolution satellite images and putting little stars on every single blister that I could see, I eventually came up with over 1,100 robber holes. I can't tell you the exact number because I kept on losing count.

It gives you a real sense of the destruction that's happened to the site, but also the extent of the site, because you don't dig robber holes unless you're finding something. Pretty much where there aren't robber holes, the chances are there wasn't a site.

This is important because if you contrast the map that we were then able to generate with the world heritage nomination document, the site is actually a lot smaller than was suggested in the nomination document. This is significant because if you've got limited resources, you don't want to be wasting your money and your resources protecting areas where there's nothing there.

It also means that the local people can do stuff in much more of the landscape than these protection zones, which were set up around the archaeology. This was real bone of contention with the local people. They felt that archaeology was getting precedence over their own needs for a bridge and for a road. Again, it's very important from a site management point of view.

When we saw the potential of using satellite images, I created a group called ASAGE. I got a lot of help from some students at La Trobe and from a member of the public called Geoff Smith, who volunteered to help us out as well.

Geoff Smith: Hi, Dave!

David: I thought I recognized you! [laughs]

That shows you the potential of using satellite imagery to reach out to interested members of the public. You can see here from Warwick Ball's information just what a drop‑off happens in the '80s and the '90s with field work. It just wasn't possible. Even in the 2000s, there's very little field work going on. If we can find new ways of studying sites and getting more information, we need to be doing that.

When I first started looking at Afghanistan, I realized that there is about 7 percent of the country covered by high resolution images. That doesn't sound very much, but its 47,000 square kilometres, which would take us more than a lifetime to look at in detail.

We were able to focus on certain areas, as we saw earlier. We looked in particular down in the south in the Registan Desert and Lashkari Bazar. When you zoom in and you overlay Warwick Ball's maps and the site data, I realized that there's this one site out in the middle of the desert, and there's nothing else around it. Everyone assumes nobody goes into the deserts. If people do, they're just nomads. The French explorer who discovered this site even found it difficult to persuade nomads to go in there.

You have large blanks on the map. People were just saying, "There's nothing there." We started to have a look there just because I didn't believe it. What we did, through very detailed work and very time consuming work that makes you go google‑eyed, we identified what were possible archaeological sites. We created about 1,800 place marks.

Then I sat down and I went through all of them. I threw out about 80 percent of them because I didn't think that they were solid enough to be confident that they were real archaeological sites. Then my colleague, Fiona Kidd in Sydney went through the ones that I'd picked out as being real ones and she threw out a few more, but what we got left with is still over 450 archaeological sites that we are very confident are real archaeological sites in an area where there was one previously. That gives you a sense of the potential for discovery using Google Earth.

What type of sites were we finding? At the very basic level, campsites. Here we can see modern camps with the tents and the corrals. This staining in the ground is from the urine from the goats and the sheep. Next to them you can see these rectangular features and circular features, which are the tents and the corrals from older camps. Obviously these campsites are likely to be relatively recent, but they're starting to give us an idea of what to look at in the landscape and how to interpret it.

Then you can get cemeteries. Nomads, as we've seen earlier, tend to bury their dead on high places and in burial mounds. These tumuli are all part of a large cemetery with more important people having a little enclosure around their burial.

This is one of my favorites. This is from actually north-west of Afghanistan. It's probably a caravanserai, which is a way station, a roadside cafe. It's positioned there because you have a valley going off this way and this valley coming through here. Down at the bottom, you can see modern trenches that have been dug in on the promontory trying to control access at this key meeting point of route ways. Again, you see the lasting strategic value of sites.

What was really interesting when I started looking around for comparable plans was, I found this plan of a site in Iran dating to about 1400. It's virtually identical. This is what gives me confidence in saying this is probably an early / middle Islamic caravanserai.

Then you get more recent structures like this one, which is probably a farm house on the edge of cultivated areas. Here we get into a bit more enigmatic things, but I'm sure you can recognize down here there's some sort of mounded structure. The two bumps are probably towers from the fortified entranceway to this occupation mound.

The curious dots around it are the spoil heaps from digging underground water channels. These are throughout the Middle East and North Africa as well. They're known by different names, but essentially you dig down, you dig sideways. All the dirt you throw out on either side creates these holes and rings like donuts. When you start seeing these things, you know immediately what they are. They stretch for hundreds of kilometres in Iran. That's one of the things that members of the public get very excited about when they see these and they talk about aliens and all that sort of thing. Sorry, no. No aliens.

When you're in the desert, you see these linear features, which are probably dams to collect the rain. Of course, it does rain in deserts maybe once every 50 years. When it does, that's a great opportunity because there's grazing associated. Nomads will quickly go into there. In places like North Africa, they opportunistically sow in different areas, trying to guess where the rain is going to fall. If you control the water, you control the area.

This is where the Corona spy satellite images start coming into their own. The image on the right is the modern Google Earth image, where you could easily say, "These are just bulldozed features." But they appear in the 1965 Corona image, and they probably appear in earlier images as well.

I suspect that these are hand‑dug small reservoirs that people have been working on for hundreds if not thousands of years. They are not modern mechanically excavated features. There's a pretty good match. Using the image overlay that I showed you earlier, it's quite easy to take these spy satellite images and to swap them over and twist them a bit and say, "Yep, there's a good match here."

Then we have the site that first of all excited me about the area. Qal'a‑i Hauz, which is the Fortress of the Reservoir. It was discovered, as I mentioned, by a French explorer in 1971, I think, 1970. It was part of a large journey that he did through the desert. He doesn't really go into much detail about the site, and the photographs are very, very poor, but here it is, just sticking out the sand.

It was a real "wow" moment when I came across this. I thought, "This is amazing." You can see. You have the large rectangular reservoir beside it and these enigmatic features around it, which are probably hunting hides. We have historical reports that the Ghaznavid princes of the 11th century headed out into the desert hunting gazelle. This is probably one of the places where they had their base camp and then they'd head out hunting.

What we've been able to do is, by drawing over the satellite image, to create the first plans of these sites. This is really important because, as you saw earlier in one of the captions, so many of these sites have not been recorded in detail before. It's not ideal. It's not totally accurate, but it's better than nothing.

When we start looking at different types of sites, we get to see different distribution patterns. Here is the distribution of the karez, the underground water channels. They're only found north of the Arghandab River because that's where the hydrology and the geology allows this sort of feature.

When you start looking at the dams, there's more of a scatter of them through the desert, but they tend to be a bit more in the area just to the south of the river. When you look at the smaller reservoirs, they're clustered in this area because that's where most people would have gone, but there are also fairly major ones further south into the desert. You're looking about 75 kilometres distance from the river into the desert, so it's not a small trek.

If we move to the west, to the Ghaznavid capital of Lashkari Bazar. This site was excavated by the French in the 1940s and 1950. It stretches for seven and a half kilometres along the Helmand River. It's a huge, huge site. As you can imagine, with a shoestring budget, they weren't really able to do a lot of work there. Although they did some excellent excavations and mapping of some of the palaces, there are big gaps in what they were able to do.

Here you can see a photograph of this Ghurid period archway, which is on their plan there. There's a lot of blanks in between. When we started studying the satellite images, picking out small wall features and hollows that show up on different colors, we were able to create a much more detailed map of the town and fill in a lot of these gaps. The same applies for the rest of the site stretching to the north. This is weeks and weeks of work. Very slow work, but it bears results.

Finally, talking about the lost minaret of Sakhar. I guess this is the ultimate in armchair archaeology. In 2005, we tried to get to Sakhar. The minaret in Jam was only discovered in 1957 or publicized in the West in 1957, but there were reports of a 30 metre high minaret from that same period down about 75 kilometres to the southeast.

I bought a high‑resolution satellite image for this valley here around the coordinates in Warwick's gazetteer. I stared at it and I stared at it and I stared at it, and I could not see something that I was really sure was a minaret. We tried to go there, but the security situation just wasn't safe for us to go that far into the hills. Ever since then, I've been contacting people in the region saying, "If you're ever in the area of Sakhar, have a look for the minaret. Please, please."

Eventually, an Afghan called Fazal Ahmad sent through via a friend of mine in USAID this photograph of the minaret. It's not terribly impressive. It's actually in a different valley compared to the one where the coordinates are for the gazetteer, which partly explains why I couldn't find it. It shows you the benefit of having local knowledge.

Two weeks ago, this got posted on Facebook. There's a page by some Afghan journalists working in Ghor Province in the centre of the country. Normally they post photos of missing people. It's very poignant. When I was told to have a look at this, it suddenly jumped out at me. "This is the minaret of Sakhar!" There is a blown‑up version of the actual minaret from a different angle compared to the one that Fazal took.

The best parallel that comes to mind is this Seljuq minaret at Daulatabad in the northeast of Afghanistan. It's not an exact parallel, but some of the decoration is similar. It's clearly part of a tradition of medieval towers that had been built in the centre of Afghanistan in the 12th, 13th centuries. For me, this is a really exciting discovery. There's always been rumors about this minaret. There's been suggestions it was one of four attached to a palace, but we've never, ever seen an image of it. And here it is.

Hopefully, you'll have a sense now of what I do when I'm staring at the computer, wasting time. You'll see the potential of it, which is huge ‑‑ the potential for new discoveries to get to inaccessible areas. To monitor sites in particular is important where sites are under threat. This applies to Iraq and unfortunately to Syria these days as well.

The ease with which the data can be shared is breathtaking. It allows international collaboration. People like Geoff...I've never met Geoff. We just communicated by email. I said, "This is what I'm looking for. This is the area I want you to look." A couple weeks later, he'll send me through some placemarks. That's been fantastic.

It's a way of engaging with the general public. I think that's something that archaeologists don't do well enough. We tend to write scholarly articles. We get a bit sniffy about talking to the media or talking to the public. I think that's a major failing.

There are pitfalls. The GIGO principle, if you know computing: Garbage In, Garbage Out. If you get the wrong coordinates for a site or if the coordinates aren't accurate enough, then you're not going to find what you're looking for, but you might find something else.

You do need to ground‑truth, which means, ideally, going there or getting somebody who is there to have a look at what you've seen. I can be relatively confident about most of the things I see, but it's always good to get somebody on the ground to pick up a few pottery shards, which we might be able to date and to get extra information.

There's the threat that does this sort of research causes looting or encourages looting. It's something that you weigh up with your conscience. I don't think it does, because at the end of the day, a lot of these sites have been looted before Google Earth, and they will be looted again in the future whether we look at them or not. What we can try to do is tell people about them and say, "These sites are important. They are of international significance."

As you saw with the case of the minaret at Sakhar, the preservation of that minaret is very poor. If we can create some publicity about it and, hopefully, get some sort of engineer out there to try and find a way to stabilize it, then that will be a positive outcome. It shows the Afghan people that there are people around the world who are interested in helping them protect their own cultural heritage. I think that's one of the most important messages that this sort of research can send.

With that, I'll just say thank you very much to everyone who's helped me over the years with this research. Thank you.

Adrienne: Please put your hands together and thank Dr. David Thomas.

Transcription by CastingWords