by Sarah Parcak
In the fields surrounding the city, many suggestions of structures show up beneath the surface as crop marks. Some lines indicate earlier field boundaries from modern times, while others trace out structures with the same size and shape as the clear features in the satellite imagery. I spoke to farmers from surrounding villages and the town of San el Hagar, and all described in detail the mud-brick structures they encountered while digging, as well as the dense ceramic debris.
In the 1960s, a decade from which we have good CORONA satellite imagery, Tanis seems to have been about 50 percent larger than today. Modern agriculture has cut into much of the lower-lying site to the north and east, and San el Hagar has grown by 500 percent. We have also lost the evidence of the ancient relic watercourses to the east and south.
The site would have looked quite different 200 years ago, during the Napoleonic expedition. The Description de l’Égypte, the expedition’s 23-volume report, was published between 1809 and 1829 and included a detailed survey of the entire country. This extraordinary volume can now be found online.33 In the online map of Tanis, the site appears to be twice as large, although that is only a rough estimate.
It might help if we imagined the landscape surrounding Tanis 3,000 years ago, in which many smaller sites formed a network of villages and estates supporting the capital. During the yearly inundation of the Nile, the main city became a large island surrounded by smaller islets. We will not know the extent of this network until archaeologists carry out a campaign of coring and noninvasive surveys around Tanis, which will take years to complete.
The Bigger Picture
Understanding the nature and extent of Tanis and its wider community has major implications for the study of Egypt and of the Near East, where we see the earliest foundations of modern city living. For the first time, having established a map for Egypt’s largest and most continuously occupied capital city, our satellite work fills in a big missing puzzle piece. But when we look closer, we see other puzzles to solve. We can create all the hypotheses we want about the spatial construction of the settlement and the nature of urban life at this specific capital, but to go further will take careful excavation.
We archaeologists have made so many assumptions about major sites around the world. The more satellite technology advances, the more we find out how little we know. My team and I got WorldView-3 satellite imagery recently, with .3-meter data and an even farther reach into the middle-infrared part of the light spectrum, and we can see twice as many structures at Tanis as in the WorldView-2 data.
For instance, when we originally analyzed the house that the French team excavated with what we had available, one small interior room showed up. Using the more powerful WorldView-3 data, with a higher resolution, lots of smaller rooms appeared there, and in all the houses of Tanis. Hundreds of houses and structures appear across the site, in parts of our original data that we assumed were blank. We’re now busy doing a 3-D reconstruction of the new houses at Tanis, which will help bring even more life to the site.
But no one data set catches everything. The usual rules of times of year, or maybe drought versus an unusually rainy spell, apply. Those palaces in the original imagery that allowed us to imagine the daily lives of royalty 3,000 years ago are completely empty in the higher-resolution WorldView-3 data. Once again, the season the imagery was taken, and the weather, have played their parts; the newest imagery seems to be from a slightly drier time of year.
Just to keep us guessing, additional phases of architecture in the central city we hadn’t seen before do pop out in the new data set. After seeing the differences between old and new, we want to test data of varying resolutions from different seasons. That will take time. And now we have WorldView-4 imagery to test34 and dozens of new Tanis images. Our headpiece of Ra is multifaceted and not as easy to use as the one that Indy just had to stick on a pole of the right length.
At the very least, this more powerful imagery helps archaeologists choose more carefully and productively where to excavate. With the improving quality of the data, we can write far better grant proposals—or increasingly, do better pitches to private donors—to show with a high degree of accuracy what we’ll be focusing on during our field seasons. Being able to say, “This season, the team will excavate two elite and two poorer houses at Tanis, to compare living conditions and access to both food and materials in a wealthy city,” and then show the exact outlines of the chosen houses … well, that’s convincing to any interested party.
A Clearer View of Modern Cities and Their Future
Cities like Tanis give us insights into our own societies, and make us wonder what crumbling remains of our own cities will be left for future archaeologists to excavate. It’s hubris to think our society will survive in perpetuity. Look at Tanis now, and just imagine telling a Tanite of 1000 BC that the city’s entire footprint would be lost.
Our cities will evolve alongside our concept of what makes a city and what about it is worth keeping. As I write this, many cities across the United States are experiencing a revival, from Detroit to Nashville to Birmingham, but we do not yet know why. Maybe it’s the under-40s returning to urban centers to start their own businesses, or the craft brew movement that kick-starts redevelopment in the most unlikely of places. Maybe it’s outside investment. When we do unravel this organic process, the potential for cities once thought to be irredeemable is limitless.
But our rural towns are now crumbling instead, and society is debating whether to save them or let us become a nation of cities. Big questions, and we can get the framework for answering them by diving into our deep human history.
* * *
My Hollywood fairy tale came full circle, from discovering an ancient city on our now-ancient VHS player, to seeing the same city come to life for real on my laptop with a godlike eye from the heavens. I’ve learned that the power of understanding the past in new ways is ultimately a balance between figuring out how to use new technologies and coming up with better questions to push the technology to its limits. Sometimes it works, sometimes it doesn’t, and that’s okay.
We occasionally get answers to our questions, from the brush of a trowel, a drop in a pipette, or a new, applied algorithm, but answers are momentary, like a cool breeze on a hot day in Tanis. All we can really do is hope we are digging in the right place.
6
A Grand Tour
On the streets of Birmingham, Alabama, one of my favorite things to do is to peer down street-repair holes. I should probably get a better hobby, but I love seeing the layered streets that have built up over time. A few stretches of cobblestones remain around our town, and walking there, I imagine horses, buggies, and the people from long ago. History lurks beneath our feet almost everywhere.
What we may not appreciate is the sheer number of sites, or even civilizations, lying beneath deserts and forests that archaeologists have not yet discovered. Finding a new feature on a site, or a new site altogether, is one thing, but now, using space archaeology we can find hundreds, thousands, or even tens of thousands of new sites and features.
This enormous scale is transforming archaeology so rapidly we have to formulate new questions to ask as we go. A century ago, or even 20 years ago, archaeologists could not have imagined the size of these data sets. Analysis of big data like this is itself quite a young field, but computer scientists are beginning to collaborate more closely with archaeologists to formulate mapping and modeling approaches.
Figuring Out What We Don’t Know
Also, we have no idea how much we have left to find. Archaeologists certainly consult inscriptions, ancient texts, and papyri for clues to lost palaces or the whereabouts of a king’s missing tomb. German archaeologist Heinrich Schliemann’s obsession with the Iliad from a young age, and his later search for the city of Troy, is probably the most famous example of discovery through the study of ancient literature. Determined to find the city, Schliemann began work at a site called Hissarlik in Turkey in 1871, obliterating many le
vels from later time periods in his excavations. Today, we know the site as Troy, and you can still see the massive Schliemann trench. But there are limits to what written sources can tell us.
We have tax records from Roman Egypt that list dozens of ancient town names, but the names of modern towns may not be similar enough to give any hints of where the old towns and cities might be. If it is so easy to lose a town important enough to appear on the tax rolls, good luck finding the smaller places that never ranked a mention. In fact, I am often asked how much from ancient Egypt is left to discover. This is an impossible question—my favorite kind.
If only 1 percent of Egypt’s wealthier tombs have been discovered, we can easily extrapolate this to all the poorer cemeteries, the settlements, vanished temples, industrial areas, quarries, and military outposts. And then just take that to the world, to unexplored and inaccessible lands in the Middle East, Africa, Central Asia, and the Far East. Consider the rainforests of Central and South America, the wilderness of Canada, the deserts of the American Southwest, and the Arctic plains. Millions of square kilometers currently lie beneath oceans, previously exposed during ice ages and covered over due to climate change or geological forces.1
What we do not know about the surface of our own planet is astounding, so we shouldn’t really be surprised when archaeologists make new discoveries every week—massive cemeteries, previously unknown ancient cities, or even proof that the Neanderthals created cave art.2
America’s Undiscovered Archaeology
We can start pretty close to home to get a sense of how much is out there in the rest of the world. Even the earliest European occupation of the United States is still not mapped fully. In 1540, Hernando de Soto and his band of conquistadors apparently explored all the way to North Carolina from their original landing spot in Florida,3 with some potential evidence uncovered in McRae, Georgia.4 Even today, the exact location of sites such as Mabila, where de Soto fought the legendary Chief Tuskaloosa somewhere in Alabama,5 is the stuff of mystery and near fisticuff-level debates at yearly conferences at the University of Alabama, so I’ve been told.
Only 350 years ago, the skyscraper forests of our cities were real, untamed forests. Prior to European colonization of North America, Indigenous occupation stretched back 18,000 years. Evidence from mitochondrial DNA suggests that there was just one migration into the Americas at that time, and that all modern Indigenous people are descendants of that original population.6 Known sites of human occupation so far are 14,000+ years old.7 Six hundred generations—that’s tens of millions of people—lived there before the first documented historical contact with Europeans in 1492.
Maps show original names and locations of these Indigenous groups, and others whose names have been lost. They reveal a well-traversed land.8 Some groups moved seasonally to hunting or fishing grounds, extending the reach, and potential traces, of their cultures.9 In Northern California, Siskiyou County alone has more than 10,000 sites,10 and the county is 1/26th the size of the state. Assuming similar site densities throughout California, that means there could be a quarter of a million known archaeological sites in that one state, and that means tens of millions of known sites in the United States.
In the United States today, there are 567 federally recognized Indigenous tribes, 229 of whom live in Alaska.11 Canada has 634 First Nations groups.12 Each of these countries is nearly 10 million square kilometers: not easy to search, with dense tree cover over 40 percent of the continent, mountainous landscapes, and areas covered by snow for many months of the year.13
From the 1700s onward, the western movement of settlers across the United States, and the following displacement of millions of Indigenous people, led to the destruction of countless native sites.14 Remote sensing is beginning to give us a sense of what was lost. In the Toolesboro Mounds National Historic Landmark in Iowa, archaeologists Melanie Riley and Joseph Tiffany, from the Georgia Department of Natural Resources and the Office of the State Archaeologist at the University of Iowa, embraced LIDAR to give them new perspectives. The Toolesboro team searched for a reported enclosure from the Middle Woodland culture of 200–300 AD, and traces of destroyed burial mounds.
Success! They located the enclosure, eight mounds, perhaps a ninth, and two anomalies.15 The landscape in question is mainly forested, with only two visible mounds. It certainly shows you can’t judge a site by its tree cover, and certainly not the size or scale of archaeological sites by what is out in the open now.
Farther south, in the Everglades of Florida, where pine forests, sawgrass marshes, and dense mangroves make a standard archaeological foot survey nearly impossible, LIDAR helped archaeologists locate earthworks dating from 1000 to 1500 AD.16 Remote sensing’s potential for our understanding of the diversity and richness of native cultures is immense. Equally, our understanding of European expansion is rapidly opening up thanks to recent advances in drone imaging and more availability of low-cost or free LIDAR data from state agencies.
Such open-access LIDAR data from southern New England allowed archaeologists Katharine Johnson and William Ouimet to identify a number of previously unknown building foundations, farm enclosure walls, and old roads dating from the 18th century to the 1950s.17 This is an area mainly covered in forest today, which begs the question of how many thousands of other farms are out there.
Discoveries like this can enlighten dark times in our social history. While we have written accounts of slave-owning plantations, the archaeology on plantations in the United States is opening our eyes to the daily lives of slaves. In Maryland, LIDAR helped create 3-D maps of plantation sites at Tulip Hill and Wye Hall. New revelations included a potential terrace, embankment, slave quarters, and garden beds, though the archaeological team responsible has emphasized the need for test excavations to confirm those discoveries.18
All this, and yet archaeologists have completed surprisingly little remote sensing work in the United States and Canada, in comparison to the rest of the world. We’re learning so much as this changes.
All Aboard
We’ve probably only mapped about 10 percent of the Earth’s land surface for archaeological sites, and far less of the ocean floors. There’s still a lot to see, so let’s get a taste of the work being done globally, and explore the extraordinary scope of my colleagues’ wide-ranging discoveries abroad. I think you’ll soon share our field’s excitement for the future potential of space archaeology.
In the 1700s and 1800s, wealthy young people from Europe and America would embark on grand tours of the Mediterranean and the Middle East, marveling at the wonders of the ancient world and coming home inspired. We don’t need to limit ourselves, and we’ll travel in style, by luxury cruise liner, and by air. No dress code for dinner, but do wear something. Enjoy the boarding gin and tonic—for medicinal purposes, naturally.
Mapping the Maya
Sit back in your deck chair and relax, but not for too long! We’re heading to an area some might argue is the hotbed for remote archaeological discoveries, receiving the lion’s share of media coverage over the last few years, and rightly so: it’s not often you find tens of thousands of new features at well-known ancient sites. We’re sailing south, to Central America.
It is home to the Maya civilization, located in an area of over 300,000 square kilometers, 43 percent of which is covered with dense rainforest and other vegetation.19
Given the landscape in the area, archaeologists must use LIDAR data to look for sites, and they are racing against time. Alarmingly, deforestation plays a role in the destruction of archaeological sites, as well as the environment. We can track the trees that have been lost through illegal logging, the use of chemicals in farming, and drug production, but we have no idea of the number of ancient sites that have disappeared.
As you saw earlier, the LIDAR revolution began with the work of Diane and Arlen Chase in Belize. As part of the same study, the Chases used LIDAR to map a 9-square-kilometer area in west-central Mexico around a site called Angamuco,
which was built by Aztec rivals known as the Purépecha. Their findings showed a major urban settlement with hundreds of residential areas connected to monumental architecture.20 After those astonishing results, other Mayanists soon received funding for their own LIDAR mapping efforts.
With that, I invite you all to board helicopters for a bird’s-eye view of the stunning landscape the Maya occupied. On the way inland toward Guatemala, you fly over the rainforest in Belize. Looking down at the sea of green, you realize just why fieldwork there, in the company of jaguars and fer-de-lance vipers, is not for the faint of heart. I had the chance to work on the Belize Valley Archaeological Reconnaissance Project there as an undergraduate, and for two glorious weeks, I lived in the rainforest, helping to map cave systems used by the Maya for burials and ritual activities. Even walking through the buttress roots, vines, and creepers was a struggle.
As you enter Guatemalan airspace and approach Tikal, arguably the country’s most well-known site, limestone pyramids peek out from the canopy just like in the scene from Star Wars: The Empire Strikes Back, but with the beautiful addition of noisy scarlet macaws. The movie was filmed here, and the view is otherworldly. No imperial stormtroopers to worry about in reality, but the botflies, which lay maggots beneath your skin to chew out on hatching, are far more terrifying.
It’s hard to see anything except the monumental structures from above, and on the ground, the rest of the site is obscured by dense vegetation. In early 2018, a major announcement focused on the area. Using the largest LIDAR data set ever collected for archaeological research, a team of archaeologists analyzed more than 2,100 square kilometers in 10 distinct areas within the Maya Biosphere Reserve in Central America, targeting Tikal, Holmul, and other large Maya sites in Guatemala. To date, they have mapped more than 60,000 previously unknown buildings.21