You can see the shape of the pueblo if you know what to look for. The mounds that were once hulking adobe buildings of two or three stories stretch across the field and if you look the right way you can see the shape of what were once huge public plazas, bordered by long roomblocks that could have housed hundreds, maybe thousands of people. Inside the plazas are circular depressions, kivas where people performed religious ceremonies six hundred years ago when this place was one of the largest settlements north of Mexico, long before my own ancestors came to this continent.

I hold up an aerial photograph of the site, handed out by the archaeologist who's giving my class a tour, and match where we are in the rippling landscape compared to the much clearer view from above. I pick out the corner of a plaza and a circular anomaly in the photograph that must be that depression to my left: a kiva, certainly, judging by its size and shape.

This is the fourth pueblo we've visited on our weekend field trip, and now my eyes know how to read them. I can see not just the shapes of buildings and holy spaces around me but also the looter's holes dug by people more recently in search of artifacts to sell. The land is owned and protected by the state, but the barbed wire fence and the signs warning people not to steal clearly aren't enough. Our class has just learned how to identify and date glazeware ceramics, but there are none to be found here, even though this site is from a time and area where those ceramics should predominate. Glazeware is shiny and impressive and interesting, and so all that remains are the plainer biscuit wares and gray wares. The neighbors of the site have reported people hopping the fence, wandering through the ancient town, and leaving with plastic grocery bags full of potsherds, the fragments of jars and bowls that someone made and broke and threw away as trash six centuries ago. They're invaluable treasure to us and to the people who steal them: little pieces of another world that's no longer part of this one.

When our tour guide mentions the looters, all of us shake our heads. As students of archaeology, we believe that the true value of the artifacts here lies in the information they can tell us, which we can only fully decipher when we know the context in which they were found. In an artifact's provenience, recorded in all the coordinates and maps and notes that we take when we excavate, we can gain more of the story of the people who left them behind than the object alone, divorced from its context, could ever give us.

Despite all the looting over the years, thousands of potsherds remain on the surface and many more must be buried just under our feet. Every few steps I can't stop myself from bending down to pick up and admire the rim of an ancient bowl or a jar fragment with a particularly interesting pattern drawn in black paint. The black and white designs on the biscuit ware can be quite beautiful and sophisticated; perhaps it's their lack of sparkle compared to the glazeware than has spared them. I pick them up, sometimes showing them to my classmates, and set them back where I found them. Every tour we've had this summer has come with the same warning not to take or to move, and I myself learned that piece of etiquette long ago.

Looters and students of archaeology aren't the only ones visiting these sites. Pueblo people return as well, to leave offerings and perform ceremonies or just to look at the ruins of the places their ancestors built, now collapsed and melted into nothing but wrinkles in the earth's surface, covered in dry brush, surrounded by barbed wire, waiting as year by year more tiny pieces of its history are stolen. To those pilgrims these sites aren't mere repositories of information or of treasure. Many Pueblo people see these ancestral sites as holy places that shouldn't be disturbed.

Perhaps the looters just want to feel connected to the past, the same way I feel connected when I close my eyes and picture this place not as an empty field of mounds, but as a bustling town: plazas full of children and dogs surrounded by the long roomblocks, their adobe walls neatly plastered and painted. Perhaps someone was cooking over an open fire and their hand slipped; a clay pot shattered; the geometric pattern of shiny greenish glaze paint was broken into a hundred pieces of something incomplete but still eye-catching. Just litter until it became old enough and strange enough to be worth picking up.

Finally, one of my classmates calls out that she found glazeware. It's not a piece of a vessel's rim, so it's nothing we can practice dating, but still we pass it around and admire the way it catches the fading evening sunlight. Eventually it's returned to the hand of the student who spotted it and she places it in the little socket left in the soil when she pulled it out, exactly as she found it except with the painted side down, so it won't catch the light next time someone walks across these mounds.

In the sixties, a small part of this pueblo was excavated by a field school like ours, from our own university. Our tour guide chuckles as he describes photos he saw of college students in short jeans cut-offs, the men shirtless and the women in bikini tops digging through this site. A few of those students became great archaeologists themselves; I recognize a name as the writer of one of my textbooks.

Then our tour guide becomes more serious, describing how the professor who lead the field school never analyzed their findings, never published any of it. The journals of the students lie unread on some dusty shelf in a museum's collections.

The excavators had been collecting artifacts into paper bags, labeled carefully to record where each piece of pottery or stone tool or ornament or butchered animal bone was found. According to our tour guide, at the end of one season they loaded everything into the bed of a pick-up truck. Summer is the best season for excavation, but it's also the time of the monsoons. The truck drove back through a storm that darkened the sky and dumped rain on the parched desert and on the truck, seriously damaging the paper bags and all the information they held. When it arrived at its destination, all that was left was a mess of soggy brown paper and the artifacts, far from home with nothing to say where they came from or who pulled them out of the ground.

The field school only excavated a small portion of the pueblo. Some of my classmates express a desire to make a master's thesis or PhD project of going through what's left of the field school's collection and notes, to decipher what can be deciphered and save the knowledge that was taken but never understood, never shared. At the same time, we imagine how amazing it would be to excavate more of the site, start from scratch and do it right this time. Of course, as we all learned in our very first Intro to Archaeology class, our science is unique because it's inherently destructive and so can never be replicated. No one can go back and right all of what was done wrong in that early excavation.

And anyway, now in a time when archaeologists in the United States consult with modern-day native people for approval of such projects, excavations of these big pueblos are few and far between.

Looking out at this lonely place, so empty and yet so full, I almost understand why the Pueblo people today might not want to see archaeologists tear another fraction of it apart. At the moment, I'm not sure I can imagine pushing a shovel into these mounds, or taking any more of its pieces away.

On weekdays, when we aren't out on field trips, our class is excavating a tiny two-room field house, a small structure used by farmers around the same time when people lived in the big pueblo we visited and others like it. The little ruin is perched on the edge of an arroyo that will soon swallow it, if not this monsoon season then the next or the one after that. Every artifact we take from the site we place in carefully labeled plastic bags, the kind of ziploc sturdy enough to be rated for curation. We take careful notes, record where the artifacts were found, draw maps of each stone in each tumbled down wall, take photos. Each of us keeps a journal of what we find each day and what we think it meant.

It's intoxicating. Each piece of six hundred-year-old garbage is magic. As I'm digging I try to remember that some long-dead person made each vessel, cooked or served or stored their food in it. Maybe their child, centuries since grown up and dead as well, broke it. They threw it out and forgot it and were forgotten themselves and now here I am holding it in my dirty hands. If we hadn't come along, the arroyo a few meters to the west would have washed all this away and crushed it to sand. I want to believe we're on a rescue mission to save the story of these people before nature destroys all trace of them.

Other times I remember that burial to some is not just death but also peace, a peace that I am disturbing. I have no way to know what those who lived here would have wanted.

Maybe it doesn't matter if the people who built this house would have wanted it left to crumble away. They're dead and gone, after all, and maybe our greater good and scientific mission should win out. I do truly believe that I am doing important work; we're contributing to a growing wealth of knowledge about our human heritage, about not just who these people were but who we all are. Each shovelful of dirt I move from the site, each number I carefully record, is for this sacred mission. I'm taking part in a communion with the whole human species and the way the world used to be. To me and my culture, far removed as it might be from theirs, I am honoring these people by helping the world remember what they built and what their lives were like. I like to think it's what they would have wanted, too.

When we've finished our excavation of the little field house, we have to backfill it—bury it again with all the dirt and rubble that we've removed. Backfilling is standard practice at the end of an archaeological excavation. The sites we dig are safer under the ground, where they're protected from further disturbance by weather and unwanted visitors. Preservation is best when the sites are hidden away under the sandy desert soil.

Before we start the backfill process, we leave a few recently minted coins on the field house's floor. If anyone else digs here they'll know that someone already excavated the site, and when.

Part of me wants to stay here and keep digging, to tear through the floors for any more pieces of the past we might have missed. That part of me thinks it's a shame to rebury it, where in all likelihood no one will see the knee-high remains of these walls again before the whole site tumbles into the arroyo that's already begun eroding it away.

Nevertheless, we replace the dirt and rubble, now empty of artifacts. Mostly empty, that is. As we are moving the huge pile of dirt back to where we took it from, we find a few artifacts that we overlooked somehow when we sifted bucket after bucket of soil through our screens during the excavation. One of the things we find in the backdirt is part of the mouth of a tiny vessel, a half-cylinder of thin clay painted on the outside with a red slip. Judging by the circumference of the fragment, the vessel when whole might have been about the size of a fist. Our professor says it was probably a seed jar. I wonder if the miniature pot might have been a child's toy. We put it and the handful of other missed artifacts into a plastic bag, all together although they could have come from any of the different areas we dug. We label the bag as unprovenienced; we have none of the precious context to go with it, none of the information that separates archaeology from looting. We're students; mistakes happen.

It takes us a day and a half to rebury the site. My back aches from filling buckets and carrying them from the pile of screened dirt back to the field house. My legs are covered with green bruises from bracing the buckets of dirt against my thigh as I lift them. My hands are torn from carrying the rough stones that used to be part of the field house's walls, which collapsed into meaningless rubble hundreds of years ago. I feel a moment of guilt, leaving the site empty of anything but a few overlooked sherds and the coins, which remind me of the coins the ancient Greeks buried their dead with to pay for passage to the afterlife. The field house is no more than a skeleton now.

Once the walls are fully buried, we toss the rest of the rubble into the arroyo, since leaving it on top of the mound might make it too conspicuous to passers-by. Of course, there's nothing left here for them to steal anyway.

We throw the remaining stones that were once walls into the arroyo, where the next monsoon flood will carry them far downstream, away from what's left of walls they were once one with. One day the rest of the skeleton of a house that we left behind will join them as the land crumbles away, little by little, under the rain that once gave life to the people who lived and farmed here. Because of us, this place won't be forgotten just yet.

My body, at least, bears witness to our work here in the physical penance it is paying for my intellectual pursuit. Perhaps this is the best way to share fellowship with these people and our human heritage; hard work, digging into the earth, gathering some kind of harvest.

As we drive away that last day, I'm not sure whether to be sad that no one will see this place again, or glad that it will finally be at peace.

Images provided courtesy of Ashley Jeanne Harris.