Archaeology from Space

by Sarah Parcak

  Beyond the Delta lies the barrenness of the Western Desert, which is the gateway into the Sahara. Here, 9 million square kilometers have witnessed countless changes in climate, from wet to semiarid to dry and back again. It spans 10 countries, with large areas too inaccessible to explore, so the best way to search for its hidden treasures is from space. Unless you happen to be a camel, in which case, go for it.

  An ongoing project in southwestern Libya led by David Mattingly and Martin Sterry from the University of Leicester has located more than 180 cemeteries and 158 new settlements amid the sand. Using high-resolution satellite imagery, drones, and photos taken from kites, the project has led to new insights about the Garamantes, a so-called lost civilization that flourished from 300 BC to 500 AD.49 The team’s efforts in Libya and Tunisia have revealed thousands of other forts, settlements, roads, and cultivated areas, showing the true scale of occupation in the region.

  Sites Under Fire

  As we sail along the coastlines of Israel, Lebanon, and Turkey, you’re seeing the landscapes of the other great remote sensing revolution in the world. While Central America is leading the charge for the use of LIDAR, archaeologists in the Middle East have found sites at a jaw-dropping scale.50 We’ve barely begun the archaeological interpretation of all this new data. In 23,000 square kilometers of northeastern Syria alone, a Harvard University team looked at lower-resolution satellite imagery and digital elevation models using data sets from several different seasons and detected 14,000 archaeological sites.51 Given the ongoing conflicts in Syria, parts of Iraq, and Afghanistan, remote sensing has been an invaluable way for archaeologists to continue their mapping work.

  In Afghanistan, David Thomas of La Trobe University in Australia has focused on the use of Google Earth for site mapping and planning. In 2008, he noted that only 7 percent of Afghanistan—46,000 square kilometers—had high-resolution Google Earth coverage. In that small area, archaeologists knew of about 250 sites, but only 33 of them had detailed architectural plans; the countrywide database stands at only 1,300 sites at present.52

  Working in a country like Afghanistan carries major risks. Thomas described one incident in 2005 where his team’s chartered plane didn’t show up when they were trying to get back to Kabul. They had to drive all the way back, a distance of nearly 500 kilometers, and nearly crashed into an artillery canon casually left in the dark outside one village, in the middle of the road. When he asked the airline why the plane didn’t show up, they told him, “Stuff happens.”53 Stuff is not the word I would use here.

  His team looked at 45 medieval sites, only 8 of which had available plans, and used satellite imagery to draw their above-surface features. They discovered 451 additional sites, which included campsites, dams, enclosures, dwellings, and hamlets, giving a site density of 0.32 sites per square kilometer in the Registan Desert region alone. Afghanistan has a total area of 653,000 square kilometers; if the entire country was occupied to the same extent, there could be more than 209,000 additional sites.

  This is not surprising. The country is at the crossroads of East and West, valued by conquerors, ancient and modern.54 Ongoing work at the University of Chicago’s Afghan Heritage Mapping Project has discovered numerous new settlements, caravan rest houses, and relic river channels, tripling the number of known sites.55

  We can follow those caravans west to Jordan, a country roughly one-eighth the size of Afghanistan, but with an equally rich history. Here, we see the work done over the past three decades by David Kennedy of the University of Western Australia and Robert Bewley of the University of Oxford, using tens of thousands of aerial photographs.56 In an area of western Jordan, where only 8,680 sites were known to the Jordanian Department of Antiquities, they found more than 25,000. At their estimates, 100,000 sites could be there.57

  With high-resolution Google Earth imagery now covering almost all of Jordan, Kennedy and Bewley are continuing their efforts via the Endangered Archaeology in the Middle East and North Africa project. Based at Oxford, this project aims to map the ongoing threats to sites across the region.58 The MEGA-Jordan website,59 supported by the Department of Antiquities, has a database of more than 27,000 known sites,60 meaning a site density of 0.3 sites per square kilometer. And that’s just the known sites.

  The World’s Most-Mapped Countries

  We’ll continue east, stopping off in Rome for some gelato and pasta. Time to stretch our sea legs—we’ve traveled some 60,000 kilometers!

  Italy is basically one gigantic archaeological site, since people have occupied its landscapes intensively for thousands of years. Led by Rosa Coluzzi and Rosa Lasaponara of the Istituto di Metodologie per l’Analisi Ambientale, a team there used LIDAR to discover a medieval village in southern Italy, revealing buried structures61 and mapping ancient river channels in the Apulia region.62 Also, multispectral and aerial photographs combined with ground-based remote sensing helped reveal a detailed outline of the Roman city of Altinum near the Venice Lagoon.63

  Europe has a long tradition of using remotely sensed data sets, and many archaeologists there were early adopters of satellite imagery. But despite large areas of Europe being so well mapped, we keep getting surprises like new hillforts, Roman villas, and medieval churches.

  As we head through the Mediterranean and north, we’re nearing the end of our journey.

  If we were to say that the Brits love maps and mapping, that would be a wee understatement: the United Kingdom is one of the most well-mapped countries in the world, and it even forces its London cabbie-wannabes to memorize and take tests on the “Knowledge,” more than 25,000 street names and 20,000 places of interest, plus 320 routes between all those locations.64 It takes three to four years to pass.

  It’s unsurprising that the United Kingdom has more than 190,000 listed archaeological sites,65 and for a country of 243,000 square kilometers, that is a lot of sites. And there is more to map—try 17 kilometers of Roman roads in Lancashire.66 LIDAR data is now available across a large part of the country, going back to 2008, and ranges in resolution from 25 centimeters to 2 meters. The availability of those data sets sheds new light on known sites and is already changing British archaeology. In the summer of 2018, due to unusually low rain levels, crop marks appeared by the bushel in fields across the country, prompting archaeologists to launch drones to capture the ephemeral hints before they disappeared again.67

  Across the Channel in Belgium, similar efforts with LIDAR have revealed a potential Iron Age hillfort as well as Celtic field-and-barrow complexes beneath forests. The technology has allowed the team from the Flanders Heritage Agency to combine management for wildlife with ancient feature preservation.68

  Underwater Archaeology

  On our return voyage across the Atlantic to New York, look down into the depths of the ocean. I’d be missing our eighth continent if I did not point out underwater archaeology and its great potential. While satellites cannot see through deeper water because of the reflection of light off its surface and the water’s movement, cutting-edge applications of remote-sensing underwater technologies are making progress. I’ve heard estimates from specialists of three million shipwrecks remaining to be discovered globally. Given the challenges of searching deeper waters for wrecks and sites submerged as the result of earthquakes or higher water levels, satellites and drones might be our most cost-effective tool for finding all sorts of underwater features.

  Google Earth is a simple but valuable tool, with imagery taken during low tides capturing a 1,000-year-old stone fish trap off the coast of Wales.69 NASA scientists have already shown how free, lower-resolution Landsat-8 imagery can reveal shipwrecks in coastal waters by identifying sediment plumes, streamers of sand and dirt from the sea bottom pushed to its surface by the movement of currents over submerged objects.70 Drones are now being deployed to help find shipwrecks beneath the surface of Lake Huron in the northern United States.71

  Since that kind of imagery is only able to capture features close to coasts, ocean dr
ones like the OpenROV,72 a briefcase-sized machine that anyone can purchase and use, will contribute much to archaeological discovery and shipwreck mapping. In the future, additional spectral bands in satellite imagery might improve mapping below the surface of oceans and lakes. I volunteer first for any related survey work in the Greek islands. You all know it will be a huge sacrifice for me.

  So What Is Left to Find?

  Let’s rephrase the question posed at the beginning of the chapter: Can we suggest the total number of sites left for us to discover globally? Such a guesstimate could fuel a new generation of explorers and new developments in archaeological technologies.

  Here goes. From broad-scale discoveries in previously unmapped parts of Asia, to new LIDAR data sets revealing features in already well-mapped countries, we’ve seen just how much is being discovered at present. And those are just the larger-sized features visible through remote sensing, not the small-scale sites that are still the domain of the sharp-eyed on foot.

  There are nearly 40 million square kilometers of habitable land on our planet. Just looking at larger-site densities per country, in areas that we have discussed above or those elsewhere, we get figures ranging from 0.3 sites to nearly 1 site per square kilometer, but that depends on how each individual country defines what constitutes a site. Even if we go with the lowest density of sites detectable from space published in larger area surveys and expand that to the globe, that’s 12 million potential sites.

  Extrapolating from this and from some of what I know will be announced in the next few years, I’ll go out on a limb:

  I believe there are more than 50 million unknown archaeological sites, from major settlements to small campsites, left to discover globally, above and below water. And that’s on the conservative end of my calculations.

  The scale and pace of discovery, and the big new questions it allows us to ask, put us firmly in an archaeological golden age. And it pales in comparison to what we could find with better sensors. Imagine the day when we have a space-based laser-mapping system like LIDAR, and we can map beneath all of the Earth’s vegetated areas.

  We’ve been recognizably human for around 13,800 generations, and 108 billion people may have lived in the last 50,000 years.73 That’s a lot of human activity to trace. With my estimate of 10 percent of the Earth’s surface already explored archaeologically, we still have close to roughly 36 million square kilometers of habitable area remaining,74 without counting shipwrecks or inundated sites under oceans, seas, lakes, and rivers. I could be horribly mistaken, by the way; the number of unknown sites could be far higher or far lower. I’m counting on one of you to prove me wrong.

  When we have a better sense of the global range and type of archaeological sites and can collect the data from their surfaces and below the ground, what we find will grant us access to new insights about how and why civilizations emerge, rise, collapse, and, with resilience, rise again.

  7

  Empires Fall

  Now that we’ve toured a world of archaeological discoveries, I know you’re jet-lagged. Let’s park ourselves at the Mena House Hotel for a while and enjoy a drink, gazing at the Giza pyramids that rise just beyond the hotel’s lavish gardens. Pull up a thick-cushioned chair to a low brass table. A waiter in a red tarboosh will take your order; I like an ice-cold hibiscus juice after a long day out—fresh, tart, and a little sweet.

  A View of the Past, and a Lesson for Our Future

  After 4,700 years and without their original limestone casing, the pyramids still command our gaze, even on a hazy day, from downtown Cairo some five miles away. They make us ask questions of ancient Egypt and of ourselves, including why pyramid building at such an immense scale stopped, and why Egyptian culture rose in the Old Kingdom, ultimately fell, and rose again in renaissance during the Middle Kingdom.

  We also wonder if anything from our own time will last through future millennia. Our impermanence is laid bare in the presence of the pyramids; they hold lessons for us today as we try to keep our footing in a world that seems ever more turbulent.

  When those monuments stood as gleaming white sentinels along the banks of the Nile, the Egyptians surely did not imagine the empty, eternal ruins they would eventually become. They were busy people, building, trading, plotting, learning, caught up in the everyday affairs of being human in a world of increasing complexity. Like us, they wrote on walls and obsessed over cats.

  After looking down and gathering insights from space, putting ourselves into the sandals of past people can give us a different perspective, especially as your seat in the Mena House bar looks out over the desert, where a vast cemetery hides a multitude of clues to ancient lives.

  Clues Woven into Stories

  From human remains, we can spin out a whole life, such as that of a poor girl from Tell Ibrahim Awad, a site in Egypt’s northeast Delta. We’ll call her Meryt, the beloved. We don’t have her real name, just the excavated bones of an adult woman. You never know what you’ll find beneath the ground, or the stories it will allow you to tell, especially after a few of the Mena House’s excellent G and Ts.

  * * *

  Meryt wound reed stems together, dangling her feet in the canal. Just another twist, and the reed boat’s prow would lock tight, ready for sailing. Or racing.

  “Hurry up, little sister! Ours are finished already!”

  Meryt shouted to Teti to go ahead. Two years older, he’d want to win anyway, guiding the boat past papyrus thickets alive with birds, to where the bank shallowed and the king’s cows came to drink. “Meryt, now! Or I’ll come and stomp on it!”

  A distant thump: her oldest brother, Seneb, had hit him with something, but Teti was giggling.

  “If you do, I’ll bash you!” Meryt shouted back. Five years old or not, when they played stick battles, she could hold her own. She set the boat into the water’s quiet gurgle.

  Downstream, a tail-whisking sea of horns and glossy coats sploshed down the riverbank, prodded along by her father. She waved.

  “Boys, don’t let a crocodile eat her,” he called. “And don’t forget the fodder needs cutting. If you want us to trade for meat, you’ll help get it in.”

  “Yes, Father,” they groaned. Teti fished his boat out.

  “And you said it’d be good, having our own field.”

  Rolling his eyes, Seneb wrung the hem of his kilt.

  “So it’d be better to have nothing to sell to the estate?” Teti thought about it. Absently he rubbed his stomach as they set off, and Meryt wound her arm through his.

  Their house was nearby, through the royal pastureland, the date groves, and their small plot. Mud-brick houses staggered uphill from the town wall, out of reach of the annual floods. Several thousand neighbors jostled the temples and the governor’s enclosure.

  Seneb grabbed some fodder for the donkey snoozing in the stable built onto the house. Inside, Mother was preparing lunch. When Father came home, they sat together and ate bread and stewed vegetables.

  “Hotep, would you take Meryt with you to town?” Mother asked, smiling at Teti shoveling in the last beans. She glanced through into the only other room, at the loom’s shroud of half-woven linen, and Father nodded.

  Later, Meryt held tight to Father’s hand as they wound through narrow streets and up to the Nubian soldiers beside the governor’s gate. One waved at her, but kept to his post.

  “Taxes?” asked a scribe who saw them in.

  Inside the lush courtyard, Father leaned down to Meryt.

  “Stay here, darling, and don’t make a nuisance of yourself,” he whispered.

  Not a short man, he looked very small disappearing inside a house that rose three times taller than their own and spanned wider than their field. Meryt squatted down to watch scribes sitting cross-legged, their accounts stretched across their laps. Their kilt fabric was a costly weave that Mother had tried to teach her. But a man came out wearing linen so fine his belly button gaped from behind it like an empty mouth.

  He stood o
ver the scribes, and the gold-beaded collar across his chest flashed.

  “His Majesty is pleased with the year’s taxation. He will honor your Lord with a burial place at Saqqara.” A steward looked up, mid-correction of a junior’s addition.

  “Will he really, sir? Our province gives its humblest thanks.” But the steward did not get up, and soon turned back to the figures. Awkwardly, the dignitary paused, and then left with a nervous squint at the soldiers.

  “Come, Meryt!” Father reached down to hoist her into his arms. She laughed and bit into the cake he had placed in her hand. “A treat from the governor,” Father said, smiling. “Now, shall we see about racing your brothers’ boats?”

  The Prosperous Old Kingdom

  Meryt and her family start out in a time of relative peace and prosperity in the later Old Kingdom, around 2700–2200 BC. During that long sweep, we see overall growth and consolidation of state power, with kings ruling as gods from Memphis, just south of present-day Cairo,1 and overseeing the infrastructure necessary to unite the country’s people and resources.2 Egypt’s renowned bureaucracy develops, with scribes and administrators as well as architects and artisans becoming essential parts of Egypt’s societal fabric.

  Major pyramid building kicks off in Dynasty 4 with the Red Pyramid at Dashur, when King Sneferu (2615–2589 BC) completes what becomes the quintessential royal tomb design. For such megaprojects and rapid state growth, Egypt has to reach out: Sneferu sends numerous expeditions to Sinai for copper and turquoise, to Nubia for gold, and to Lebanon for cedarwood. Dynasty 5 (2498–2345 BC) looks even farther abroad, to places such as Punt, probably in Eritrea, where traders and emissaries collect gold, incense, and baboons.