Introduction: How do we Think about Backdirt?

“There was chaos in this work. There was chaos. Take, for example, where they put the dirt they took out. Because to them, there was no problem where the dirt went. You know what I mean? When they take sand out. You know? They don’t care much where it goes.” -Ahmed el-Bedul, 2015

Ahmed is a Jordanian Bedouin who has lived his entire life in the area of Petra. When we had this conversation, he had worked on many archaeological excavations and had seen how much strategy went into other aspects of the research design and the approach to excavation. But where to place the excavated soil, in his experience, was something that archaeologists didn’t care about, hadn’t thought through, resulting in “chaos.”

Ahmed was far from the only resident of Petra to complain about the placement of backdirt and spoil heaps. Others mentioned, too, the difficulty for future excavations when meters-deep piles of soil were piled on top of still-buried sites. I (Allison Mickel) heard critiques of archaeologists who placed backdirt in wadis (valleys) and riverbeds where it would be washed away, eliminating any possibility of re-excavation or revisitation. And for some interviewees, they simply experienced the piles as unsightly—eyesores that archaeologists who only came seasonally could leave behind and ignore but which the local community members had to look at and live with every day (see also Mickel 2020).

For me (Christina Luke), there are technical experts who work and live near the archaeological site of Kaymakçı in western Türkiye. They are part of the excavation team, and they often ask for the backdirt for their house gardens and agricultural fields because it is “pure,” without stones, and “old,” so implicitly “better.” At Kaymakçı, excavations take place between May and July, and excavated soil is sifted context-by-context, and earthen features form adjacent to the trenches. When excavations close (usually in late July), the soil is transferred to a designated zone. At this time, the soil can’t be reclaimed for agricultural use because it is slated for future (re)use as backfill. The extreme winds that whip the Kaymakçı ridge make reconstruction of mudbrick walls and other superstructures untenable. Preliminary concepts for site-presentation include multi-sensorial installations embedding community-artistic approaches with eco-performance that will complement digital imaging (e.g., virtual and/or augmented reality). To realize this option, open trenches will need to be sealed, likely with backdirt to responsibly backfill, and then mirror the architectural grid on the face of the landscape (compare Neve 1987, 1998). This approach differs significantly from other regional earthworks of archaeological backdirt, such as at Sardis (1910–1914; see Butler 1922; Luke and Çelik 2023) and at Karnıyarık Tepe (Hanfmann 1972, 149–155; Luke 2019, 175).

To both of us, it was striking to encounter so much concern, emotion, and thought among local stakeholders about backdirt compared to the paucity of discussion on the topic in the archaeological literature. There are offhand mentions scattered throughout various site reports and publications, of course, and several researchers have investigated what can still be learned from previously excavated contexts. From looters' pits (Powers and Swift 1984) to material from construction projects (Alvey Scott and Buchanan 2015) to archaeological dumps from earlier excavations (de Beeck 2006), particular case studies have shown that spoil heaps and dumps often contain artifacts with the potential to shed light on the past. Research on backdirt, such as Quitmeyer’s (2004) experiments with screen sizes and faunal assemblages and Wright and colleagues' (2021) use of XRF to examine the geochemistry of spoil heaps, has informed archaeological methods and research design. Discussions of conservation best practices, meanwhile, have debated the sustainability and desirability of backfilling sites as a conservation strategy (e.g., Agnew et al. 2004; Cooke 2007). Backdirt also shows up in discussions of community engagement and student education, where previously excavated soil provides an opportunity for newcomers to practice archaeological methods without damaging stratigraphic contexts (e.g., Moshenska, Canós-Donnay, and Fernández Fernández 2019; Sert 2014).

These individual uses and case studies with backdirt, however, have not coalesced into a coherent literature. It is clear that archaeology is in need of, on the one hand, a theory of backdirt and, on the other, a best practices of backdirt. That’s what this pair of special issues sets out to establish—or at least to begin.

The conversation around backdirt is so nascent that archaeologists do not even agree on what we should call the soil that we remove from archaeological sites or what the stakes are for this terminology. When we released the call for papers for this special issue series entitled “On Backdirt,” we received reminders from archaeologists in the United Kingdom and Australia who cautioned us that “backdirt” is an American term, and “backfill” would be more common nomenclature on their projects. Others wrote to us and asked if “spoil” or “spoil heaps” were what we were really asking about. Yes, we replied, we are interested in all of it—whatever you call it. But it is worth noting that Lingle and Seifert, in this issue, distinguish between the meaning of “backfill” and “spoil heaps,” noting that excavated soil piled outside of a trench constitutes a spoil heap and can only become backfill when it is replaced—backfilled—back into the site. It is exactly this sort of attunement to meaning, context, and precision that we hope to introduce to discussions of backdirt. No more throwaway terms for this once-throwaway material.

Our authors offer and operationalize various thoughtful definitions for excavation soil throughout this pair of issues. Pijpers begins his reflection with the definition of “Back Dirt” from the Archaeological Institute of America: “The excavated, discarded material (sediment, dirt) from a site that has generally been sifted for artifacts and is presumed to be of no further archaeological significance. This material may later be used to refill test pits, an action referred to as ‘back filling’” (Archaeological Institute of America 2024). Krupa and Thomas, however, critique this very definition, questioning the phrase “of no further archaeological significance.” … “Significance for whom?” they ask. Indeed, their paper and many others in this set of issues illustrate that backdirt is indeed of much archaeological significance—because of what it contains, what it can do, what it can teach, and what it means.

For Weber, whose paper addresses the potential dangers that backdirt can contain, her definition centers on the backdirt that remains on the archaeological site rather than being dispersed or repurposed. In her analysis, backdirt is “by definition the sediment that is removed from excavation units and backfilled later,” building into the definition the proximity to the archaeological site. Meanwhile, Carvalho—focused on what can be learned about past excavations from backdirt—puts forth a definition that contains past decisions and chosen methodologies inside of it: “the soil that is removed and set aside during the excavation process, being screened—or not—through a fine mesh in order to recover any artifacts or ecofacts that may be present.”

Other authors define backdirt beyond the material, with Hanson and Fladd calling backdirt “a choice.” They are especially interested in the decisions made about when investigation ceases, and frame backdirt as “a choice that is rooted in and guided by the historically- and culturally-situated contexts and motives of research and researchers.” Rivera-Prince and Morales urge a shift from thinking about “backdirt” as static to “backdirting” as a process, saying: “Backdirt is not just a passive, static substance at the end of the excavation process. Backdirt is active in creating a place that is different from before, and a place that will continue to exist in the landscape and enter new relationships. Backdirts not only have a role in making places, but are part of the continued production of places, and the continued narrative of different places’ histories.”

Embedded in all of these definitions is the critical dilemma of backdirt: with most artifacts removed but itself an artifact of the excavation process, it exists between nature and culture, between past decisions and future purposes, dangers, or significance. It is no longer stratified, inviting questions about its “usefulness” to archaeology—taunting the researcher to make a decision about its finality, to leave it behind. But wait: it may still contain artifacts, or retrievable information, or material properties useful to conservation, or spiritual importance. And there it sits, usually piled on or near the archaeological site, demanding decisions to be made or, at least, for bodies to keep moving, moving around it as the pile grows.

In this collection of papers, we refuse the binary of stratified significance versus the supposed no-further-significance of backdirt by instead raising a series of questions about what backdirt does and can do. Questions like:

What does backdirt hide? Krupa and Thomas, for example, point out that “cremated remains can be extremely difficult to extract from soils due to their friable and brittle state,” and Weber details the limitations of site monitoring technologies to detect various hazards and contaminants in previously excavated soils. Shiff’s examination of Tel Burnat shows how sifting methods and new discoveries in backdirt can lend historical conclusions both scientific and popular weight, hiding their contemporary political influences and contingencies.

What does backdirt reveal? In Chaco Canyon, Hanson and Fladd suggest that “backdirt can continue to reveal the priorities that structured the original excavations that are often left unstated.” Sawerthal points to the thousands of small finds recovered from the Temple Mount Sifting Project—though of course, like Shiff, there are political claims being made through these finds. And Rivera-Prince and Morales offer a virtual list of things that backdirt reveals: “cultural and temporal values manufactured by archaeologists that reflect when they worked,” “archaeologically relevant stratigraphy,” and “the narrative of a site’s history.”

What possibilities does backdirt prevent or foreclose? Some backdirt, simply by virtue of existing, can block further excavation or construction until it is moved (Sawerthal). For Howley, excavating at Sanam Temple, encountering the backdirt and past excavation decisions of Francis Llewellyn Griffith: “Our initial reaction to the traces of Griffith’s archaeological presence at the site was therefore one of negativity towards the seemingly irresponsible and destructive techniques of early 20th century a.d. archaeologists which, we believed, obscured our ability to reconstruct Sanam’s past.” And the backdirt explored in Weber’s contribution prevents certain excavation strategies or sifting methodologies—for instance, some ammunition-containing backdirt “that could possibly get stuck in the screening machine and explode.”

What possibilities does backdirt enable? While backdirt can be stubborn, it can also open up a “way for archaeologists to study themselves” (Carvalho) and “a network of relations” between past and present archaeologists (Howley). It can make possible claims to religious and political identity (Shiff; Sawerthal). And it enables novel strategies for conservation of fragile archaeological remains (Lingle and Seifert). Backdirt is as much a beginning as it is an ending.

How does backdirt modify the landscapes of archaeological sites? Backdirt, Rivera-Prince and Morales tell us, “is active in creating a place that is different from before, and a place that will continue to exist in the landscape and enter new relationships. Backdirts not only have a role in making places, but are part of the continued production of places, and the continued narrative of different places’ histories.” Rivera-Prince and Morales illustrate their point with case studies from Peru, discussing how visible cuts and dirt heaps call up memories and meanings for local community members. Lingle and Seifert suggest that existing as a “landscape feature” is one of two main roles that spoil heaps traditionally serve on archaeological sites—but invite us to consider how this soil can be used in the sort of cyclical maintenance that earthen heritage demands, has always demanded.

What does it mean to think of backdirt beyond a by-product of excavation? Can backdirt be a “resource [meriting] further methodological exploration as a material” for conservation (Lingle and Seifert)? Can we define backdirt as material culture, as human remains, as funerary object—indeed, as sacred (Krupa and Thomas)? Meanwhile, at the former Pioneer military base, the backdirt “proved not to be a byproduct, but a contested body that ‘acted up’ and thus became the reason for an unintended level of cooperation between various actors, an opportunity to successfully conduct a site investigation combined survey with EOD specialists, archaeologists and recycling management flanked by government institutions” (Weber).

How can we think of backdirt as data, as method, as result, as engagement? Several authors in this set of issues are invested in rethinking the ontological and temporal status of backdirt with regard to the archaeological research process. Perhaps backdirt can itself be a sort of documentation, for example—“a valuable and tangible record of a project’s decision making, guiding principles, and core question, including what should be excavated, recorded, collected, curated, and given additional analysis,” as Hanson and Fladd suggest. They offer, too, that other types of heritage practice (like museum deaccessioning or unpublished assemblages) could also be considered as “backdirt.” Howley raises backdirt’s ability to connect the past and the present, producing “echoes and parallels” across disparate time periods. And for Pijpers, employing a theoretical framework of “ecopoetics,” backdirt is primarily a sensory relationship between archaeologists and landscape. He refuses a cerebral distinction of backdirt as unimportant and instead sees “touching and excavating the dirt” as a way of “both being exposed to and implicated in a relation of ecopoetics to the Earth.” Backdirt, according to Pijpers, may be considered as “infrastructure,” stabilizing the landscape and the excavation process itself.

We have worked to organize the two issues that follow like a well-curated dual-sided album, leading the audience through a natural sequence in which each paper picks up on motifs of the prior. This first issue, “A Theory of Backdirt,” focuses primarily on theorizing backdirt, while the forthcoming second issue instead puts forward best practices of backdirt—though of course, in reality, theory and practice are not as discrete as this separation seems to suggest. We begin with our most theoretical contributions (Rivera-Prince and Morales; Carvalho; Pijpers), starting with Rivera-Prince and Morales’s paper, which offers an excellent literature review of backdirt. We then shift to papers that bring well-developed theoretical perspectives to bear on backdirt in specific places and particular times (Hanson and Fladd; Howley).

In the forthcoming issue, “A Practice of Backdirt,” we transition into case studies of backdirt—case studies which still offer theoretical guidance but which are perhaps more tangible in their discussions. These case studies center on backdirt as volatile—whether physically (Weber) or politically (Shiff; Sawerthal)—backdirt as sacred (Krupa and Thomas), and backdirt as a practical tool for heritage conservation (Lingle and Seifert). We conclude, in the end, with a reflection on shared possibilities, remaining limitations, and invitations to continue to think about the place of backdirt in archaeological practice around the world.