Despite what is shown in movies and on TV, most archaeological finds are not golden treasures or priceless pieces of antiquity. Most are items that were used on a regular basis and then discarded due to wear, damage, or loss. This chapter introduces you to the types of materials archaeologists frequently uncover and the settings in which these materials are most often found.
We tend to think of archaeologists as primarily studying objects made by humans (artifacts), but there is much more to archaeological investigations. Archaeologists are most concerned with context—how an artifact or other type of archaeological data was found in relation to everything else at the archaeological site. A site is a distinct clustering of artifacts in a location that demonstrates human activity, and the number of artifacts needed to qualify a location as a site varies based on the context and, at times, excavation funding. An artifact’s context includes its provenience, exactly where the object was found (horizontally and vertically) in the site; its association in terms of its relationship and positioning with other objects; and the matrix of natural materials such as sediments surrounding and enclosing the object in place. When a site is looted or excavated by amateurs, the context of the artifact is lost even if the artifact is left behind. Excavation strips the site of much of its most important information, components that tell a fuller story of the object and the site, leaving behind an item with no story left to tell. Ideally, items found during an excavation are left in situ, which is Latin for “still,” meaning they are in their original place of deposition. This is why archaeologists tell you to leave any item you find, especially on public land, untouched no matter how tempting it is to pick it up, look at it, and put it in your pocket to show your archaeology professor!
As previously discussed, artifacts are objects that were used, modified, or made by people. They are also defined as portable and could have been carried by humans from place to place. Common examples of archaeological artifacts are projectile points (arrowheads), ceramic pots, baskets, nails, and glass bottles. Of course, there is a natural preference for complete artifacts since many objects at sites were discarded and were broken before being found, entering the archaeological record because they were thrown in the trash. As a discipline, however, archaeology must analyze all types of artifacts to get the most complete picture of human occupation and behavior. It is also easy to miss single-use artifacts such as a rock used to pound a tent stake in place because no one packed a hammer or mallet. Archaeologists spend much of their time thinking about and analyzing artifacts because the items were made or used by humans and correlate directly to human behavior. Thus, many features of artifacts can be analyzed, such as the material from which they were made, their artistic or functional style, and their design. Archaeologists also create typologies, which provide a way to understand how an artifact such as a pot changed over time in shape, form, and use. Typologies also provide useful estimates of the period in which the artifacts were made.
Besides artifacts, archaeological sites provide ecofacts: organic and environmental remains such as animal bones, plant remains, and soils that occur at archaeological sites but were not made, modified, or used by humans. Ecofacts can reveal much about human behavior. For example, plant and animal remains can allow archaeologists to reconstruct the environment when humans lived there, effectively telling researchers what types of plants or animals would have been available for humans to use. Another type of object found at sites is a manuport, which is an object brought to the site by humans but not modified by them. For example, an unusual stone material known for its excellent heating properties could be found in a hearth or fire pit. A feature is an artifact such as a hearth, storage pit, midden (trash pile), house, or other structure that is not portable. Together, all of these pieces of evidence observed at and collected from an archeological site make up an assemblage.
Archaeological sites, which are reflections of human behavior and activities, come in many varieties. At the most basic level, they can be broken down into open sites and natural shelter sites. An open site is one that had no protection from the elements while natural shelter sites such as caves and rock overhangs provide protection from the elements. A cave is technically defined as an opening in a cliff or rock face that is deeper than it is wide, setting it apart from a rock shelter, which is typically a shallow rock overhang or cliff. Site type provides important information for archaeologists. It indicates the likely function of the site and allows archaeologists to predict the types of artifacts and ecofacts likely to be uncovered. An open site, for example, will rarely contain well-preserved perishable artifacts or features because of damage from wind, rain, heat, and cold. Caves, on other hand, are excellent places to find preserved perishable items such as wooden artifacts and basketry.
Archaeologists also pay attention to the potential functions of a site—how the site was used by humans. Naturally, an important function of many sites is habitation; artifacts are concentrated where people lived for more than a few days or weeks. Sites of short-term habitation such as encampments typically offer few archaeological remains simply because of the short time humans were there. Sites where food was acquired and, in particular, processed are important parts of the archaeological record. They include processing sites where humans prepared plants or animals for consumption, such as animal kill sites and butchering sites; storage sites where items such as grains were kept for long periods of time; hunting blinds and traps humans used to catch and kill animals; and agricultural sites where humans cultivated crops for food and other uses.
Archaeologists are interested in many other types of sites as well, including quarries where humans harvested stones for tools and building and lithic scatters (sometimes at quarries) where they made and repaired stone tools, which are called lithics. Other sites provide information about human cultures and uses of symbolism, such as rock art sites at which humans painted pictographs, carved or etched petrogylphs, and scraped rocks and the soil to make geoglyphs. Cemeteries also yield important information about a people, even without exhuming the bodies. Finally, more recent excavations dealing with historic archaeology have focused on travel routes such as historic and prehistoric trails identified by shallow linear depressions over the ground and rock faces. Industrial and commercial sites are also an important part of historic archaeology and have a profound impact on our understating of economies of the past.
Context at a site is critical to understanding the archaeological data fully. Archaeologists need to understand the types of artifacts and sites they encounter, how such remains can enter the archaeological record, and what can happen to them after they are deposited by humans. The study of what happens to archaeological remains after burial or deposition is called taphonomy. Taphonomy is important because it is likely that buried and deposited objects are not in situ when uncovered by archaeologists. Determining who or what could have caused the item to move from its original depositional location to the current location is important to understanding the complex contextual information presented at the site. For example, a plow in a field could churn the soil, disturbing an unknown archaeological site and redistributing the artifacts. This type of action, caused deliberately or accidentally by human activities, is called a cultural formation process. Natural events, such as a wind storms, floods, volcanic eruptions, and even the effects of plant roots and animal burrowing, are called natural formation processes. When archaeologists understand what forces and events could have had an impact on the position of archaeological remains, they are better equipped to answer questions about whether marks on a bone came from animal gnawing or are signs of early human tool use and whether a collection of artifacts was deposited haphazardly or was affected by a mudslide.
Archaeological excavation is the systematic and controlled process of digging at a site to recover and record evidence of past human activity. It is a destructive process, so it is done with meticulous care, involving careful documentation of finds and their context through notes, maps, and photographs to answer specific questions about history. It may surprise you to learn that, while the techniques used to interpret particular types of materials came about separately over time, the processes of excavation and interpretation of broader contexts for those materials (archaeological theory) has changed a great deal over the last two centuries.
Changing Frames of Interpretation
It seems that people have always been curious about cultures of the past, but not all of those efforts were purely scientific. Evidence of the evolution of techniques for studying the past goes back at least as far as New Kingdom Egypt when officials preserved monuments from the Old Kingdom. King Nabonidus of Babylon dug into the temples of his predecessors in search of objects belonging to earlier time periods, which we call antiquities. What today would be called pothunting or looting—digging up items for their value rather than as part of a scientific endeavor—was a widespread and accepted practice used for thousands of years to acquire antiques and relics for personal collections.
These excavations began to take on some elements of scientific study as people who were specifically interested in the past began to excavate sites to learn more about past cultures and peoples, but the scientific method was not employed. Such early projects included excavations in 1709 at the ancient Roman town of Herculaneum, where artifacts were collected but not analyzed. Generally, historians excavating sites at the time found it difficult to conceive of times and peoples such as the ancient Greeks, Romans, and Egyptians. Some of what we consider to be great historical sites, such as Stonehenge, were attributed to the work of elves, trolls, and witches.
Why did those early excavators attribute their finds to mythological creatures and not to humans? Largely because of their limited frames of reference and perspectives, their paradigms,which guided their research. During this early period of archaeology, researchers and the general public in Western Europe and the United States believed that the Bible was a literal, historical document. Consequently, they understood that humans did not exist before Biblical times (in which Adam and Eve were the first humans), restricting human history to approximately 4,000 years. Anything discovered that appeared to be incongruent with this strict interpretation of the Bible, such as “primitive-looking” stone tools and structures, was attributed to non-human sources.
Scientists, however, began to challenge those beliefs with research and data. Geologists, biologists, and botanists discovered evidence that showed that humans had existed far longer than had been interpreted from the Bible. Scientists were also challenging other literal Biblical translations and were drawing new conclusions. Their evidence accumulated, culminating in Charles Darwin’s work on evolution via natural selection, which described how species had changed over time. This became established as part of the realm of science and general public knowledge. Darwin’s work fundamentally changed the study of biology and human history. Researchers tried applying his premises to other fields, including the study of human civilizations. Herbert Spencer, E.B. Tylor, and William Henry Morgan independently applied Darwin’s principles to the study of civilizations across the globe, developing approaches that collectively became known as Progressive Social Evolutionary Theory (PSET), in which human civilizations were seen as points on a continuum and as having progressed in a linear fashion along this continuum from savagery to barbarism and, ultimately, to enlightened, civilized society. It was assumed that all cultures had originally been primitive and were in the process of becoming more civilized—more evolved. These theorists placed cultures along the continuum using particular diagnostic characteristics that included adoption of agriculture, development of a writing system, tool technologies that relied on metallurgy, and belief systems focused on a single god. Proceeding along the continuum (toward civilization) indicated how “developed” a culture was. We know today just how incorrect this was.
Perhaps it is not surprising that the traits of civilized society essentially described the Western European culture of the theorists and developments made possible by the environmental conditions in those areas. Metallurgy, for example, was possible because Western Europe was endowed with many natural ores. However, the data they collected did not always fit the model. They labeled many early cultures such as the Maya, Aztecs, Incas, and North American tribes as having “devolved”—moved backward on the continuum—because they found evidence that those cultures had possessed “civilized” traits at one time but no longer did.
These and other challenges to the PSET framework were initially ignored, particularly because a large body of research, such as work by Danish archaeologists Christian Thomsen and J.J.A. Worsaae, seemed to support it. Independently, Thomsen and Worsaae had noted that artifacts found in layers in bogs, burials, and village trash collections called middens were deposited in a sequence: stone artifacts at the bottom oldest level, followed by bronze artifacts in the middle level, and iron artifacts in the top youngest level. This ordering of cultural developments became known as the three-age system, and it worked well in places in which early peoples used all three materials over time to make various tools. However, in other parts of the world, such as Africa and North America, people did not use those tool technologies in the same sequence, and some didn’t use one or more of the technologies at all. Many of the historians and researchers at the time chose simply to ignore this problem and even forced the data to fit the theory.
The problems associated with the three-age system and PSET were not addressed by North American theorists and researchers until Franz Boas, now known as the father of American anthropology, rejected theorizing from incomplete data sets and developed what is known as the classificatory-historicalparadigm (sometimes called Historical Particularism).Boas demanded that anthropology be conducted in a scientific manner. Therefore, theories could be developed only after precisely collecting, classifying, and analyzing artifacts. He argued that too little was known about the diversity of human cultures—past and present—and that PSET had been formulated too early and was based on too little actual evidence. Boas and others established collection of data as the fundamental task of anthropology (rather than applying a particular explanatory theory), marking the point at which archaeology became a fully scientific endeavor. This new paradigm recognized that observation must be the first step to inform the scientific method since it allows one to formulate relevant questions to pursue in subsequent steps. Theory does not start the process of scientific inquiry but rather comes out of extensive study of the natural world. Boas and his successors realized that the anthropological technique of ethnography, which involved careful observation of living peoples and their cultures, could be applied to cultures of the past via archaeology.
Boas also realized that little time was left to study traditional Native American cultures before colonization, genocide, and realization of America’s ideals of Manifest Destiny destroyed many of them. The effects of these processes were already under way. Native American populations were rapidly declining in number, being forcibly moved from their ancestral lands, and experiencing massive cultural upheaval. This motivated Boas and others to focus on Native American cultures and to collect every conceivable type of anthropological data and artifact—a true holistic study.
Their extensive research and data collection identified broad adaptive patterns shared by various cultures in regions such as the Plains, Southwest, California, and Northeast. The cultural traits of the groups in these regions were not identical but they were broadly similar. In California, for example, pottery was common, and most groups hunted and gathered their food rather than cultivating agriculture. In some cases, the regions were further subdivided when broad patterns warranted it. The Great Basin in the Southwest, for example, was subdivided into three cultural groups—the Paiute, Shoshone, and Ute. Though culture areas sometimes involve overlaps and do not describe the various cultures perfectly, they are still used today to help archaeologists better understand and compare Native American cultures and ways of life.
Within the classificatory-historical paradigm, archaeologists worked with data from these cultural areas to develop chronologies and spatial orderings of artifacts, a culture history, specific to each region. For example, W.C. McKern developed the Midwestern Taxonomic System, an artifact sequence for cultural sites in the Midwest. These chronological works were important since, at the time, there were few methods for dating artifacts and, consequently, the archaeological sites from which they came.
Prior to the 1960s, the pendulum of archaeological research had swung from one extreme to the other, at least in the United States. Early work in archaeology had viewed archaeological data through an evolutionary lens and tried to fit the three-age system that worked so well in Europe to data from North America. However, anthropologists such as Franz Boas began to realize that the three-age system and PSET did not fit the cultures of North America in general and Native American archaeology in particular. In response, they developed the classificatory-historical paradigm for archaeological research, which emphasized gathering data and conducting research over applying established theories. This new paradigm worked well and provided archaeologists with vast amounts of comparative data, but it was somewhat limiting as gathering data and analyzing artifacts did not give archaeologists the opportunity to explore broader human behavioral patterns.
Frustrated by the limits of the classificatory-historical paradigm, archaeologists began to introduce a third paradigm, processual archaeology, in the 1960s. They wanted to examine human behavior more broadly rather than just recover artifacts, so the primary idea underlying processual archaeology is that artifacts and data can be used to explain the past, not just describe it. At the same time, new technologies such as computing and absolute dating techniques were providing researchers with new kinds of data and analytical capabilities that simply did not exist before.
Lewis Binford, an American archaeologist who is often cited as the father of processual archaeology, advocated for the importance of theory using a new technique, ethnoarchaeology, which applies ethnographic techniques used by cultural anthropologists when comparing living peoples to the archaeological record. This approach relies on ethnographic analogy, or interpreting the archaeological record based on similarities observed in ethnographically described cultures. Binford, for example, accompanied Inuit hunters and studied the debris they left behind at hunting stands. He then used that contemporary data to predict what Inuit hunting stands of the past would have looked like and to interpret hunting artifacts found in Inuit excavations.
Since the focus of processual archaeology was on theoretical interpretations of data, several theoretical approaches developed over time that made explicit the connection between the specifics of archaeological data and the broad theoretical applications. Middle range theory (MRT), for example, was based on the idea that linking archaeological data to theories is a matter of linking artifacts made by people to the behaviors that created the artifacts. American archaeologist Kent Flannery advocated use of systems theory, which was designed to help researchers see the complex whole as a series of smaller subsystems that could be pulled apart and analyzed independently along with the whole. Ultimately, these theories were deemed to be unnecessarily complicated and unworkable with actual data. Once again, broad theoretical applications were found to be suitable only in some situations and to be too broad to have general scientific value.
Processual archaeology was not scrapped despite failing to meet many of its lofty goals. Quite the opposite; it is still actively used today. Processual archaeology’s lasting contribution is its use of data and scientific methods to support theoretical applications and analysis, and some of the theoretical approaches proposed, such as predictive human behavioral models, continue to be used in evolutionary ecology to predict and interpret past human behavior. These models, common in economic analyses, use data to identify optimal human behavioral patterns: which food items to include in their diets, patches in which to forage, how far to travel to hunt, etc. The resulting description of optimal behavior does not necessarily reflect what past humans did but does predicts the choices humans would have made if they could rationally optimize their choices. Surprisingly, some of the most interesting results occur when the model predictions do not match the archaeological data. For example, California archaeologists have used this approach to understand why acorns, which were a time-intensive, low-calorie food source, were widely used by many of California’s Native American groups. Those groups were not acting “optimally,” but the sheer abundance of acorns combined with declines in “more optimal” food sources made acorns a practical “best” solution.
The most common optimal behavior models used in archaeology today are diet breadth (also called prey choice), which predicts what humans should have included in their diets in given areas based on how long it would have taken to find a food item and prepare it for consumption relative to the food’s caloric return; patch choice, which evaluates how productive a given environment would have been and predicts how long a group would have stayed in one area before moving on; and central place foraging, which predicts how much of an animal would have been brought back to the group’s home base given the distance to that base (the longer the distance, the less animal brought back).
Many archaeologists viewed processual archaeology as having limited value, and beginning in the late 1970s, in the midst of the feminist and postmodern movements in other disciplines, began formulating a new approach called post-processual archaeology. This paradigm stressed the potential for multiple interpretations of the archaeological record and recognized that every interpretation is affected to some degree by researchers’ biases. Its proponents argued that something as complex as human behavior could not be investigated by testing hypotheses. Instead, their goal was to obtain as broad a perspective of the past as possible by interpreting the data from various vantage points and trying to see the artifacts and data from an “insider’s” perspective (emic). The post-processual paradigm also placed a greater emphasis on obtaining information about a culture’s religion, symbolism, world view, and iconography from the archaeological record. Post-processual archaeology brought a stronger focus on the role of women, children, and minorities in the past because it encouraged archaeologists to analyze data that previously would have been ignored.
Today, both processual and post-processual paradigms are used in archaeology. This is a unique situation since, in the past, new paradigms replaced old ones. These two paradigms are quite different and, typically, college and university archaeology faculties rely on only one of the paradigms. It is rare for a faculty to be composed of researchers who use different paradigms. The same data can be analyzed from each of these vastly different perspectives to bring distinct interpretations to the data.
Archaeological Techniques
In archaeology, the first step in conducting field research is to do a survey of an area that has the potential to reveal surface artifacts or cultural debris. Surveys can be done by simply walking across a field, or they may involve using various technologies, such as drones or Google Earth, to search for unusual topography and potential structures that would be difficult to see from the ground. Cultural artifacts that are found may become the basis for an archaeological excavation of the site. A random sampling of excavation units or test pits can determine a site’s potential based on the quantity of cultural materials found. GPS coordinates are often collected for each piece of cultural debris, along with notes on specific plants and animal found at the site, which can be indicators of potential natural resources. Features such as trails, roads, and house pits are documented and included in a full set of field notes. Government agencies have different protocols about what constitutes an archaeological site; the standard in many areas is six cultural objects found in close proximity to one another.
When preparing a site for excavation, archaeologists will map the entire area and divide the site into square sections using a grid system, which involves roping off measured squares over the surface of the site. This grid system enables archaeologists to document and map all artifacts and features as they are found in situ (in the original location). All objects and features uncovered are assigned catalog or accession numbers, which are written on labels and attached to the artifacts. These labels are especially important if artifacts are removed from the site.
Mapping, Statistics, Geographic Information Systems (GIS), and Remote Sensing
It is worth stepping aside before discussing materials in relation to one another to better understand how archaeologists begin by determining those relationships. In archaeology, relationships range from global and regional (such as the trade of artefacts or the geologic makeup of a region inhabited) all the way down to microscopic ecofacts (pollen or food residues on tiniest chips of pottery).
Somewhere in-between, the blending of traditional mapping with modern technology has resulted in the emergence of Geographic Information Systems (GIS) and Geographic Information Science (GIScience). The GIS focuses more on the software and hardware used, while GIScience focuses more on the applications of those technologies to scientific disciplines. For simplicity, this chapter will use GIS as a generic term to refer to both the systems and science. GIS is not a single method, concept, or program. Instead it is a way of organizing, displaying, and analyzing data that has some type of geospatial component. This interdisciplinary science has been applied to fields from cultural anthropology to urban planning, wildlife management to mining, and economics to anthropology, among others. In today’s world, GIS is often intimately tied with Remote Sensing (RS), which is a set of methods that allows for the collection of data without anyone being physically present at a location and without needing to directly observe the objects being studied.
Pedestrian surveys are a cornerstone of archaeology, relying on teams of archaeologists and volunteers who walk sites in specific patterns by lining up approximately two meters apart at one end of an area and slowly scanning the ground for artifacts, pausing to examine finds, record GPS coordinates, and complete standardized "tag and bag" forms with date, location, identifier, and contextual information, though spacing varies by research design, ground cover, and project logistics—CRM projects on tight budgets may use 10-to-20-meter spacing depending on state requirements, while well-funded excavations at known protected sites maintain the two-meter rule since finding important artifacts is more certain. Pedestrian surveys are often accompanied by systematic shovel test pits (STPs) arranged in grid patterns over surveyed areas, where excavation tools dig test holes typically 30-to-50 centimeters in diameter and up to one meter deep (adjusted based on site specifics and artifact age), with screens sifting excavated material to catch small artifacts and systematically assess where further excavation is needed, though CRM contexts may use STPs in areas with ground cover obscuring pedestrian surveys or where legally required, while skipping them in low-probability areas to save time or where conditions like exposed bedrock or recent lava flows prevent digging. Mapping is essential for archaeologists who must interpret cartographers' maps and create their own, beginning by determining orientation through north arrows or compass roses, then understanding scale—the ratio showing how much the world has been reduced to fit the image, such as 1 centimeter on a map representing 100 meters in reality.
Rough hand maps made during surveys help archaeologists envision site activity and are digitized through photos or computer applications, though these sketches are typically rough and not to scale since few archaeologists are artists, making them vital for field notes but requiring technology to produce accurate, presentable versions. Once survey and STP data are collected and artifacts curated, archaeologists convert pen-and-paper records into digital spreadsheets eventually compiling them into databases with data entered in specific columns in numeric format for compatibility with other programs, though many archaeologists now skip conversion by recording data directly in the field using applications or specialized mobile apps that organize information into columns and rows.
Statistical analyses are essential for most archaeological work, ranging from identifying surface feature differences to detecting artifact frequency changes, and can involve simple counting or advanced calculations like t-tests and ANOVAs, with spreadsheet programs handling the mathematics. Common statistical programs include IBM's SPSS (affordable for students at around $80/year but expensive for professionals at $100/month as of 2024) and its free open-source alternative PSPP, which offers similar graphical interfaces and coding options while promoting research equity, as well as R programming language with RStudio's GUI for running statistical tests, though it requires coding knowledge.
After entering data into spreadsheets and running necessary statistics, archaeologists import data into Geographic Information Systems (GIS) software—typically ArcGIS (the paid industry standard) or QGIS (the free open-source alternative)—in .csv or other spreadsheet formats, then use tools to convert raw data, often GPS coordinates from pedestrian surveys or STPs, into displayable layers that overlay data onto backgrounds for visual inspection. Archaeologists create multiple maps through cartography to display information differently for various audiences and highlight specific findings, such as showing survey paths on one map and artifact counts per STP on another. Beyond creating maps, GIS programs are powerful tools used throughout the archaeological process for planning pedestrian surveys, creating buffers around features like houses or roads, analyzing topography to predict artifact locations, and conducting data analysis and peer review, with modern applications now closely integrated with aircraft and remote sensing technologies.
GIS programs rely on GPS satellites that provide meter-level accuracy for public use (approximately 5 meters on consumer devices) and millimeter precision with specialized systems, though accuracy is better in countries like the United States with government program ties but reduced in remote areas and the Global South due to fewer satellites. NASA and USGS's Landsat program (ninth iteration launched September 2021) offers publicly available imagery with 900-square-meter pixel resolution useful for surveying large areas but insufficient for identifying structures due to atmospheric distortions that bend light and prevent high-resolution satellite imagery. Aerial photography from airplanes and helicopters, used by archaeologists for site mapping and discoveries like Peru's Nazca lines, offers superior resolution at lower cost, with USGS's EROS archive providing 1-meter to 15-centimeter pixel resolution for the continental United States, though limited by charter costs and airport distances.
The past 20 years have seen the rise of Unmanned Aerial Vehicles (UAVs or drones), which consume significantly less fuel than airplanes—many running only on batteries—enabling cheaper, more frequent imaging tailored to specific concerns, with the FAA's "Part 107" pilot license allowing anyone over 16 to fly UAVs professionally and gather their own imagery. The ability to target specific field sites multiple times across multiple days allows archaeologists to gain aerial imaging benefits without satellite launch or airplane charter costs, with weather being less of a concern, and detailed data collections combined with GIS and remote sensing software create detailed maps, 3D models, and virtual reality experiences like the Vanderbilt Initiative for Interdisciplinary Geospatial Research's Andean archaeological sites, which uses data from researchers via the Geospatial Platform for Andean Culture, History, and Archaeology. Remote sensing techniques use electromagnetic waves, sound waves, electrical fields, magnetic fields, or seismic waves to detect objects beyond human senses, including sonar (SOund Navigation And Ranging) developed for ship navigation that sends sound wave "pings" and listens for echoes to calculate distance and detect motion through doppler shift, helping archaeologists find sunken ships and buildings from the surface using Remotely Operated Vehicles (ROVs) equipped with sonar and radar to map the ocean floor.
Radar (RAdio Detection And Ranging) uses radio waves bouncing off objects to detect size, position, and motion through doppler shift, familiar from traffic speed detection and weather monitoring, with ground-penetrating radar (GPR) allowing archaeologists to image beneath dirt or solid rock without digging by using radio waves that move through soil but reflect off larger objects, saving time and energy by revealing exactly where to dig. LiDAR (Light Detection And Ranging) works similarly by sending laser pulses toward objects and measuring reflection time to determine distance, with thousands of detections creating three-dimensional environmental maps offering increased speed and precision due to light's much shorter wavelength than sound (LiDAR ~900-1,050 nanometers versus sonar ~1.5 centimeters to 1.5 meters), extensively used to discover sites in otherwise inaccessible places. Archaeologists use publicly available NASA and USGS satellite data like Landsat 9's 11 bands capturing specific electromagnetic spectrum segments (including thermal imaging) to detect landscape features, combining bands into true-color images (representing human vision) or false-color images (showing invisible wavelengths) that highlight specific objects like Maya ruins covered by jungle, with the Normalized Difference Vegetation Index (NDVI) measuring plant health and uncovering ancient Mesoamerican cities. On-site nondestructive techniques include Acoustic Reflectance (sending sound waves through dirt with sensors at regular intervals to create three-dimensional views), Electrical Resistivity Imaging (measuring how easily electricity passes through materials via electrodes placed at regular intervals), and magnetometry, which uses magnetometers to sense magnetic fields generated by artifacts like iron nails or steel swords measured in Gauss (G), creating three-dimensional images or detecting indirect evidence like fasteners to infer locations of wooden objects, though archaeologists must predict site materials since vegetation can hinder ground-penetrating techniques and sites from pre-iron periods lack magnetic fields for magnetometry detection.
Digitizing archaeological sites and data is becoming increasingly necessary for archaeologists. In the past, data may come from pedestrian surveys, shovel test pits, or full-sale excavations which simultaneously provide data and destroy the site we are studying. Modern techniques like remote sensing, acoustic reflectance, and magnetometry help archaeologists gather data and target excavations for specific purposes. UAVs help us further target remote sensing and LiDAR to build extremely detailed 3D models of sites prior to and during excavation. Once collected, data are then entered into digital format and analyzed using statistical programs. This helps archaeologists quantify sites and perform in-depth research within single sites and across multiple sites and geographic scales (from villages to continents). From there, data are put into a GIS program to create maps, identify features, and use advanced statistics to identify features that aren’t otherwise visible. These approaches are increasingly important in our digital world, as models are frequently made available to other researchers and to the general public—a vital component to both public outreach and to preserving cultural heritage.
Primary & Secondary Contexts
While remote sensing and mapping can assist excavation (and, in some cases, may be the only data available for a site that is somehow inaccessable), excavation remains the primary source of archaeological data. Excavation is a slow process. Archaeologists work with trowels and even toothbrushes to carefully remove earth from around fragile bone and other artifacts. Soil samples may be collected to conduct pollen studies. Ecofacts—objects of natural origins, such as seeds, shells, or animal bones—found at a site may be examined by other specialists, such as zooarchaeologists, who study animal remains, or archaeobotanists, who specialize in the analysis of floral (plant) remains with an interest in the historical relationships between plants and people over time.
Every cultural and natural object and feature is fully documented in the field notes, with its exact placement and coordinates recorded on a map using the grid system as a guide. These coordinates represent an object’s primary context. If uncovered objects are moved before documentation takes place, the archaeologist will lose the archaeological context of that object and its associated data. Archaeological context is the key foundation of archaeological principles and practice. In order to understand the significance and even age of artifacts, features, and ecofacts, one needs to know their context and association with other objects as they were found in situ. Objects that have been removed from their primary context are said to be in a secondary context.
Careful and proper documentation is vitally important. This information becomes part of the archaeological record and guides and contributes to future research and analysis.
This dig site in Vindolanda, England has yielded thousands of artifacts left behind by Roman occupiers in the years 85 – 370 CE. (credit: “Digging Archaeology 4” by Son of Groucho/flickr, CC BY 2.0)
Archaeological Dating Methods
Establishing the age of cultural objects is an important element of archaeological research. Determining the age of both a site and the artifacts found within is key to understanding how human cultures developed and changed over time. Other areas of science, such as paleontology and geology, also use dating techniques to understand animal and plant species in the ancient past and how the earth and animal species evolved over time.
The earliest dating methods utilized the principles of relative dating, developed in geology. Observing exposed cliffsides in canyons, geologists noted layers of different types of stone that they called strata (stratum in the singular). They hypothesized that the strata at the bottom were older than the strata higher up; this became known as the law of superposition. According to the law of superposition, not just geological layers but also the objects found within them can be assigned relative ages based on the assumption that objects in deeper layers are older than objects in layers above. The application of the law of superposition to archaeological fieldwork is sometimes called stratigraphic superposition. This method assumes that any cultural or natural artifact that is found within a stratum, or that cuts across two or more strata in a cross-cutting relationship, is younger than the stratum itself, as each layer would have taken a long time to form and, unless disturbed, would have remained stable for a very long time. Examples of forces that might cause disturbances in strata include natural forces such as volcanos or floods and the intervention of humans, animals, or plants.
The law of superposition was first proposed in 1669 by the Danish scientist Nicolas Steno. Some of the first applications of this law by scholars provided ages for megafauna (large animals, most commonly mammals) and dinosaur bones based on their positions in the earth. It was determined that the mammalian megafauna and the dinosaur bones had been deposited tens of thousands of years apart, with the dinosaur remains being much older. These first indications of the true age of fossil remains suggested a revolutionary new understanding of the scale of geological time.
It was eventually determined that if a specific set and sequence of strata is noted in several sites and over a large enough area, it can be assumed that the ages will be the same for the same strata at different locations in the area. This insight enabled geologists and archaeologists to use the structures of soils and rocks to date phenomena noted throughout a region based on their relative positions. Archaeologists call this method archaeological stratification, and they look for stratified layers of artifacts to determine human cultural contexts. Stratigraphic layers found below cultural layers provide a basis for determining age, with layers above assumed to be more recent than those below.
According to the principle of superposition objects found at deeper layers (called stratum) are older than those found above. In this illustration, the pottery fragments in Stratum E can be assumed to be older than the shell buttons found in Stratum C. The objects nearest the surface (aluminum can, plastic bottle) are obviously most recent. (CC BY 4.0; Rice University & OpenStax)
Another method of dating utilized by archaeologists relies on typological sequences. This method compares created objects to other objects of similar appearance with the goal of determining how they are related. This method is employed by many subdisciplines of archaeology to understand the relationships between common objects. For example, typological sequencing is often conducted on spearpoints created by Indigenous peoples by comparing the types of points found at different locations and analyzing how they changed over time based on their relative positions in an archaeological site.
Another form of typological sequencing involves the process of seriation. Seriation is a relative dating method in which artifacts are placed in chronological order once they are determined to be of the same culture. English Egyptologist, Flinders Petrie introduced seriation in the 19th century. He developed the method to date burials he was uncovering that contained no evidence of their dates and could not be sequenced through stratigraphy. To address the problem, he developed a system of dating layers based on pottery (see the figure below).
Petrie’s Egyptian pottery seriation method is built upon the observation that styles change with time. Petrie arranged pottery artifacts into similar groups based on stylistic features and placed them along a relative timeline based on these features. (credit: “Evolution of Egyptian prehistoric pottery styles, from Naqada I to Naqada II and Naqada III” by W. M. Flinders Petrie and A. C. Mace/Wikimedia Commons, Public Domain)
Typological sequences of pottery, stone tools, and other objects that survive in archaeological sites are not only used to provide dating estimates. They can also reveal much about changes in culture, social structure, and worldviews over time. For example, there are significant changes in stratigraphy during the agricultural age, or Neolithic period, at around 12,000 BCE. These changes include the appearance of tended soils, pollens that indicate the cultivation of specific plants, evidence of more sedentary living patterns, and the increased use of pottery as the storage of food and grain became increasingly important. Archaeological evidence also shows a growing population and the development of a more complex cultural and economic system, which involved ownership of cattle and land and the beginning of trade. Trade activities can be determined when pottery types associated with one site appear in other nearby or distant locations. Recognizing the connections between objects used in trade can shed light on possible economic and political interrelationships between neighboring communities and settlements.
Chronometric dating methods, also known as absolute dating methods, are methods of dating that rely on chemical or physical analysis of the properties of archaeological objects. Using chronometric methods, archaeologists can date objects to a range that is more precise than can be achieved via relative dating methods. Radiocarbon dating, which uses the radioactive isotope carbon-14 (14C), is the most common method used to date organic materials. Once a living organism dies, the carbon within it begins to decay at a known rate. The amount of the remaining residual carbon can be measured to determine, within a margin of error of 50 years, when the organism died. The method is only valid for samples of organic tissue between 300 and 50,000 years old. To ensure accuracy, objects collected for testing are promptly sealed in nonporous containers so that no atmospheric organic substances, such as dust, pollen, or bacteria, can impact the results.
Dating systems that measure the atomic decay of uranium or the decay of potassium into argon are used to date nonorganic materials such as rocks. The rates of decay of radioactive materials are known and can be measured. The radioactive decay clock begins when the elements are first created, and this decay can be measured to determine when the objects were created and/or used in the past. Volcanic materials are particularly useful for dating sites because volcanoes deposit lava and ash over wide areas, and all the material from an eruption will have a similar chemical signature. Once the ash is dated, cultural materials can also be dated based on their position relative to the ash deposit.
The technique of dendrochronology relies on measuring tree rings to determine the age of ancient structures or dwellings that are made of wood. Tree rings develop annually and vary in width depending on the quantity of nutrients and water available in a specific year. Cross dating is accomplished by matching patterns of wide and narrow rings between core samples taken from similar trees in different locations. This information can then be applied to date archaeological remains that contain wood, such as posts and beams. Dendrochronology has been used at the Pueblo Bonita archaeological site in Chaco Canyon, New Mexico, to help date house structures that were occupied by the Pueblo people between 800 and 1150 CE. The Laboratory of Tree-Ring Research, based in Tucson, is the world’s oldest dendrochronology lab.
The most effective approach for dating archaeological objects is to apply a variety of dating techniques, which allows the archaeologist to triangulate or correlate data. Correlating multiple methods of dating provides strong evidence for the specific time period of an archaeological site.
The Archaeological Process
The archaeological process is a generalized series of steps or tasks an archaeologist takes to develop, conduct, and complete archaeological projects, but the archaeological process is not a one-size-fits-all set of rules that can simply be applied to any archaeological project. Because each project is unique and has its own goals, requirements, and challenges, not every aspect of the archaeological process is required for all projects (though some steps are more important than others and will always be part of any project). The archaeological process is fluid. The steps in an archaeological project may not proceed in a simple, linear fashion. In many cases, the steps of the archaeological process and the order in which they occur depend on the context the project has arisen from as well as available time and money, ethical concerns, relevant laws and required permits, the needs and concerns of other people, institutional and financial delays, and more. Additionally, sometimes certain steps of the archaeological process will bleed into or become intertwined with others.
Most importantly, excavation is an important piece of the overall puzzle of archaeology, but it isn't all archaeologists do. And archaeology isn't just about digging things up!
The vast majority of archaeological work that takes place in the United States (and in many other countries) is a result of either 1) research projects (often conducted by archaeologists who work at universities or research institutions); or, more commonly, 2) cultural resource management (CRM) projects. Archaeological research projects, as with research projects in other scientific disciplines, begin with a question or a problem. The question or problem usually depends on the researcher’s interests and expertise. Some questions and problems are simple. For example, the question “What people or cultures lived in this area and when did they live here?” is commonly asked when minimal archaeological work has taken place in a particular area or region. This type of question must be answered before archaeologists can formulate other questions. Some research questions are more complex. A researcher may want to know, for instance, when a group of people became sedentary or how people at a particular settlement constructed a collective identity.
Beginning in the second half of the 20th century, an increasing number of archaeological projects were conducted under the umbrella of CRM archaeology. This was because of the increased need for infrastructure all over the world. As a result of this need, a formal effort was made to establish cultural resource laws to protect important places, landscapes, buildings, artifacts, and so on from destruction during these infrastructure projects. Today, most archaeological work performed throughout the world takes place as CRM projects.
Based on the details of the planned infrastructure project, CRM archaeologists develop a plan to identify, evaluate, protect, and excavate the sites and/or resources that includes an estimate of how much money will be needed to perform these tasks. Because they do not choose what kinds of sites or time periods they investigate, CRM archaeologists investigate all sites, artifacts, buildings, monuments, landscapes, and so on within the project area and parameters and should always strive to make thoughtful, accurate recommendations to the developers about how to best conserve, record, or mitigate archaeological remains.
Some projects are more accurately called salvage archaeology, also known as rescue archaeology. This is when archaeologists conduct archaeological work at a site that was partially destroyed or damaged or is about to be destroyed or damaged due to development, erosion or other natural processes, natural disasters and extreme weather events, civic and economic unrest, war, neglect, or looting. These projects are often necessary because not all CRM laws are created equal—some only protect certain kinds of archaeological and historical sites or sites on certain types of land. Additionally, laws are often not enforced due to limited time and resources. Even when CRM laws are enforced, the penalties for breaking these laws are not always severe enough to compel developers to comply with them. In the United States, for instance, CRM laws in some states do not protect archaeological sites on private property. Thus, landowners can legally destroy sites and do not have to pay for archaeological evaluation or excavation before they make changes on their property. Fortunately, most states have laws that protect human remains and sites with human remains, regardless of who owns the land.
Perhaps the most crucial (yet often overlooked) aspect of beginning an archaeological project is a discussion of ideas and possibilities with communities, individuals, and representatives who have an interest in or ties to the sites, objects, and time periods in question. In the United States, these communities and representatives include tribal historic preservation officers, historical societies or organizations, and communities or groups with ties to an archaeological site. Ideally, archaeologists should develop research questions and projects in collaboration with these communities and individuals so their interests, concerns, and interpretations are represented. Even CRM archaeologists, who generally do not choose where a project occurs or what sites are investigated, should actively reach out to interested parties, especially descendant communities, to inform them of the project and to get their perspective on what sites, objects, and landscapes are important to them and why. These discussions and collaborations should continue throughout all steps of the archaeological process, regardless of the order, to the extent that is possible.
Background Research
Background research is a crucial, time-consuming component of archaeology that accounts for the majority of archaeological work. Both CRM and research archaeologists must conduct thorough literature reviews covering the project area's geology, environment, flora and fauna, previous archaeological findings, site history, past excavations, property records, and landscape modifications. This information comes from diverse sources including archaeological reports, maps, census data, newspapers, and interviews with local residents or landowners. Research archaeologists additionally need to review scholarly literature on their specific topic—such as farming practices, tools, or plant domestication in a given region. Most importantly, all archaeologists must familiarize themselves with the culture, beliefs, history, and relevant scholarship of the groups they study, whether Indigenous peoples, African Americans, or other communities, as this contextual knowledge enables more informed interpretations and meaningful research questions.
Methods & Research Design
Archaeological methods encompass the procedures, techniques, and instruments used to complete projects, ranging from basic field methods like pedestrian surveys, shovel testing, and hand excavations to more specialized approaches like remote sensing with various techniques requiring specific knowledge, tools, and software. A research design formally outlines project goals, methods to achieve them, and underlying theories. For research projects, methods depend on the research questions—for example, studying settlement distribution requires surveys and diagnostic artifact collection, while diet changes necessitate excavations at food preparation sites. CRM projects use similar methods but vary by phase: Phase I involves literature reviews and surveys to identify sites, Phase II requires intensive testing like unit excavations, and Phase III may involve complete site excavation, with all phases including material analysis to evaluate site type, chronology, and significance.
Method selection depends on available funding, time constraints (such as during salvage excavations), and the principle of using the least destructive approach that still meets project goals—examining existing museum collections is preferable to new fieldwork, and limited test units are better than extensive excavations when adequate for answering research questions. Since the archaeological record is finite and excavations are destructive and expensive, archaeologists minimize site impact, though complete excavation may be necessary if a site faces destruction. Crucially, collaboration with descendant communities is essential when developing methods, as some places may be sacred or culturally significant to communities who prefer noninvasive techniques over excavation or alteration of these sites.
Background Data & Information
Funding is critical for all archaeological projects but obtained differently for CRM versus research work. CRM projects are typically funded by employers who select companies based on cost estimates, qualifications, and reputation, though this competitive bidding process can encourage low estimates that sometimes result in incomplete work. Research archaeologists, usually academics, must obtain outside funding primarily through grants from federal sources like the National Science Foundation and National Endowment for the Humanities (funded by taxpayers) or professional organizations like the Archaeological Institute of America and Wenner-Gren Foundation (funded by donations and fundraisers), making funding highly competitive since these organizations support global projects. The required funding amount depends on project goals and scale—small projects can seek less competitive local grants while large projects need major funding—and on the type of work involved, with excavations and specialized analyses being more expensive than surveys, requiring archaeologists to carefully budget for fieldwork, lab work, specialized tests like radiocarbon dating, material curation, and publication costs.
Obtaining permission is essential for all archaeological projects and typically occurs alongside securing funding. Archaeologists must understand and comply with cultural resource laws that protect archaeological materials and sites, applying for permits from government agencies by submitting project descriptions, timelines, methods, qualifications, and intended outcomes—a process that ensures quality control by limiting work to qualified professionals but can be lengthy, requiring early application. For projects on private land, archaeologists must obtain landowner permission, which may or may not require government permits depending on local laws but is always necessary and can be challenging since landowners range from enthusiastic supporters to openly hostile, making it crucial for archaeologists to build trust through friendly, patient relationship-building that demonstrates genuine interest in community well-being beyond just the archaeology. Lab-based projects similarly require permission from museums or collection curators, with more complex permit processes for destructive analyses like radiocarbon dating or DNA studies, and regardless of legal requirements, consultation with descendant communities about project goals, methods, and material handling is an ethical obligation for all archaeological work.
Fieldwork
Fieldwork, often called data collection, is where 'actual' excavation takes place. It is perhaps the most variable step in archaeology and typically takes the least time compared to other phases, though it receives the most public attention through documentaries and articles showcasing dramatic discoveries like identifying King Richard III's skeleton or detecting Maya architecture through remote sensing. While fieldwork captures public imagination and many archaeologists enjoy visiting new places, seeing artifacts, and reconstructing history as it emerges—despite real hazards like injuries, heat illness, wildlife encounters, and other dangers that must be addressed in research designs—this romantic view problematically overshadows fieldwork's true purpose of recovering information to interpret the past and the methodical, often mundane techniques involved like detailed context descriptions, mapping, photographing, soil analysis, and artifact bagging. Field schools, while important and often required for undergraduate archaeology students as training for jobs and professional development, can perpetuate the overemphasis on fieldwork at the expense of understanding that archaeology is a comprehensive process where fieldwork represents only a small portion, with equally important work occurring in libraries, labs, and museums.
Interpretation
Data processing, analysis (as in the previous chapter), and interpretation typically consume the most time in archaeology, with a realistic estimate of at least three months of work for every month spent in the field, though timing varies by project type and analytical methods required. Processing begins with washing, sorting, and labeling artifacts with contextual information like site name, feature, and level, then re-bagging them in curation-standard containers that meet legal requirements and storage facility standards—a seemingly tedious but educational task often assigned to beginning archaeologists in field schools to teach artifact identification and handling. Beyond artifacts, archaeologists must complete, verify, and digitize field notes, maps, and paperwork for backup and space efficiency, while other data types like remote sensing results, GIS data, and residue analysis must be organized, cleaned, and formatted into appropriate software or visual presentations. Analysis methods depend on project goals and research questions, with CRM projects typically requiring chronology determination through diagnostic artifact analysis (pottery, lithics) or absolute dating techniques like radiocarbon dating when diagnostic materials are absent, often sending samples to specialized labs, while research projects may involve more targeted analyses as specified in research designs and permits. Finally, interpretation addresses original research questions by blending theoretical approaches with collected data, often testing hypotheses—proposed explanations with if-then statements linking evidence to conclusions—though these hypotheses may not be explicitly stated in publications, archaeologists always interpret results by integrating questions, theory, and data to reconstruct and explain the past.
Curation & Dissemination
Curation—the cataloging, preserving, storing, and caring for archaeological collections and data—is one of archaeology's most important yet underappreciated and neglected steps, essential for making physical remains (artifacts, samples, paperwork, maps) and digital data (photographs, scanned documents, GIS data, 3D scans, geophysical data) available to researchers and the public for future study, displays, and education. Every archaeological project plan must include arrangements and funding for permanent curation before work begins, requiring archaeologists to contact curators at accredited facilities to confirm space availability and willingness to store estimated data volumes, comply with cultural resource laws that may mandate specific repositories, and create written agreements detailing parties involved, collection types, transfer dates, costs, and preparation standards like artifact washing, labeling, and digital formatting. Due to the curation crisis—an ever-growing shortage of storage space for properly maintaining archaeological collections—museums often reject "redundant" artifacts like fire-cracked rock, rubble, and unmodified stones that provide repetitive information without adding interpretive value, making it crucial for archaeologists to collaborate with curators early to understand facility policies and prepare collections appropriately for long-term storage.
Dissemination—sharing project results through reports, articles, presentations, and outreach—is one of archaeology's final and most crucial steps, representing the culmination of a project and fulfilling archaeologists' ethical obligation to share knowledge widely since nobody "owns" the past. CRM archaeologists typically publish legally required reports containing project results, site significance, and infrastructure recommendations that often become gray literature accessible mainly to other CRM professionals and employers, while research archaeologists publish in peer-reviewed journals and books addressing larger theoretical and methodological questions, with both groups presenting at professional conferences and sometimes contributing to textbooks. However, since these formats reach limited audiences and academic publications can be costly or difficult for the public to access—though open-source journals are improving accessibility—archaeologists must engage in broader outreach through public lectures at libraries and historical societies, school presentations, event booths, artifact identification events, site tours, museum displays, blogs, videos, social media posts, and interviews with radio, newspapers, and TV networks, though media interviews require careful, concise communication and proofreading to ensure accuracy. While public dissemination is vital, archaeologists must protect sites by withholding sensitive location information from public presentations, stripping location data from digital photos, and requesting reporters not disclose exact site locations to prevent looting, damage, or illegal investigations, prioritizing both public education and site preservation.
Excavating Archaeological Sites
This chapter has been a bit of a tease referring to excavation as much as it has but spending more time discussing remote sensing, context, the history of interpretations, and research design, but this is exactly because this is how archaeology is! The picture in our heads (which is cultural, by the way) of an archaeologist almost always has them digging—but this is just a tiny fraction of what an archaeologist does. That said, just because it is a tiny fraction of their time, does not mean it isn't an important part of archaeological science. Let's now take a look at the excavation strategies and techniques archaeologists do use when 'digging.'
xxx 303168 Archaeological excavation comes with three warnings:
As above, excavation is only a very small part of what practicing archaeologists actually do—and some archaeologists never go near a trowel. Background research, surveying, mapping, lab work, and analysis are all equally important components of the archaeological process.
When you excavate an archaeological site, you are destroying it. You can’t excavate the same ground twice—and this means that it is essential to carefully record everything that you do.
There are important ethical concerns about who has (or should have) authority over sites, artifacts, and landscapes of the past. This includes the power to make decisions about whether archaeological sites should be excavated—and if so, when, and by whom.
Excavation Strategy & Sampling
Excavations begin by carefully deciding where to dig based on research goals, available funding, time constraints, and legal/ethical concerns rather than digging haphazardly. Research goals drive excavation strategy—CRM excavations test site integrity and National Register eligibility on a small scale or involve full data recovery, whereas academic projects are guided by specific research questions like investigating subsistence strategies versus burial practices, with excavation locations chosen accordingly. Funding often limits excavation planning, with CRM companies balancing competitive bids against adequate resources to pay staff and follow proper research designs while facing pressure for quick, cheap completion, and academic archaeologists seeking grants from institutions, private organizations, federal sources, state/local governments, or developing field schools where student fees fund research. Time constraints affect both CRM archaeologists who must meet scheduled deadlines under developer pressure and academic archaeologists who typically work summers only between teaching semesters, often traveling internationally and navigating bureaucracy, resulting in intense field seasons with long days and minimal time off while spending the rest of the year preparing for potentially just a couple months of fieldwork. Legal and ethical considerations are crucial, requiring appropriate permits under laws that mandate coordination with State Historic Preservation Offices, Tribal Historic Preservation Offices, landowners, and other parties, with similar international requirements and protocols necessitating prolonged discussions and genuine consultation with local communities and descendant groups before any excavation begins.
Once archaeologists consider goals, funding, time, and legal/ethical factors, they select a sampling strategy, typically not excavating entire sites to preserve portions in situ for future researchers since excavation is destruction, beginning by mapping a grid to track features, unit placements, and spatial relationships using random (using random number generators for basic site information), stratified random (ensuring proportional coverage of different site sections like ritual versus domestic areas with random unit placement within each), systematic (excavating in consistent patterns for even coverage but potentially missing high-probability areas), or judgmental sampling (choosing specific dig locations to prioritize important areas but risking researcher bias), with most real-world strategies balancing these approaches, such as making judgmental decisions to excavate around mapped structures combined with stratified random sampling across different site sections. Excavation strategies also vary between vertical excavations—deep "telephone booth" style units useful for highlighting stratigraphy, seeing soil layers and occupation contexts in unit walls, reaching early time periods under deep deposits, and understanding chronology, though taking longer and providing only small occupation layer snapshots—and horizontal excavations designed to bring entire sections down to single occupation layers, showing how site parts related spatially and allowing researchers to follow walls or buildings in their entirety, though prioritizing one occupation over others by digging through and destroying later occupations to reach the target layer while potentially never reaching earlier ones.
Methods & Tools
Archaeological units—the areas dug for excavation—are usually square (typically 2×2 meters) to maintain excavation control and aid mapping, tied into the overall site grid and oriented to cardinal directions with carefully dug straight walls showing stratigraphic profiles that archaeologists protect intensely. The trowel, particularly the pointed Marshalltown masonry trowel inspiring brand loyalty among U.S. archaeologists, is the most important and symbolic tool, with field archaeologists maintaining sharpened personal trowels for years and using them for multiple purposes including cutting roots, while margin trowels with rectangular blades help shape unit corners. Other essential tools include compasses for orientation, measuring tapes to ensure correct unit size (using the Pythagorean theorem to verify 2.83-meter hypotenuses for proper right angles in 2×2-meter units), nails to mark corners wrapped with string to show wall boundaries, and datum strings with line levels hung to measure excavation depth and artifact locations.
Digging may begin with backhoes (when archaeological materials lie deep under plowed fields with monitors watching for unexpected finds), pickaxes (for compact soil), or sharpened flat-edged shovels to remove thick topsoil, then switching to hand tools once reaching archaeological levels—trowels scraping dirt into dustpans dumped into buckets, clippers cutting intrusive roots, brushes cleaning artifacts in situ, and specialized tools like bamboo implements for excavating bone without scratching. All excavated dirt passes through screens of varying sizes and styles—individual hand screens, two-person rocking sifting screens with ground legs, or larger table screens and tripod-hung screens for long-term excavations—with ¼-inch standard U.S. screen size allowing dirt through while catching most artifacts/ecofacts, though smaller ⅛-inch screens may sample for tiny items like fish bones that slip through standard screens.
Digging & Data Collection
Excavation proceeds in controlled levels using slow, scraping trowel motions to take down entire units evenly rather than creating uneven holes, pausing for notetaking, sketching maps, and separating artifacts/ecofacts by depth, with specific features like pits, hearths, or postholes excavated separately to keep context-specific items together for later dating analysis. When possible, artifacts remain in place until directly mapped on XY axes within the unit and measured for depth to understand relationships to other artifacts and site geology, though GPS coordinates may supplement mapping but lack necessary accuracy at archaeological scales in some regions.
Excavation follows either arbitrary 10-centimeter levels (useful when geology is unknown or soil lacks clear distinctions between occupations) or natural soil levels when clearly distinguishable layers help distinguish deposition events for better chronological control, with both techniques providing vertical control to track artifact origins and prevent mixing materials from different depths, while archaeologists maintain straight, clean unit walls to better identify stratigraphy crucial for determining chronology. After completing excavation and notetaking, excavators carefully backfill units to protect unexcavated site portions and avoid leaving fields full of holes. Throughout the process, careful notetaking is most important since excavation is never fully replicable—once soil and artifacts are removed, they cannot be replaced exactly as found, making archaeological excavation unique among sciences as it destroys the site, and without meticulous documentation at every stage, information is irretrievably lost.
Note-taking styles vary widely among archaeologists, with some recording excessive details including weather, mood, and meals that make important data difficult to find, while overly sparse notes frustrate researchers when needed information was never recorded, leading most excavations to use standardized forms or context sheets with spaces for essential information like site name, excavation date, unit number, level/feature number, depth and size, soil color and texture, artifact/ecofact/feature numbers and types, preliminary interpretations, and sketches. Good documentation also requires collecting quality images through photographs taken at regular intervals, supplemented by multispectral imaging or UAV aerial photos on some projects, and archaeological illustrators who record details invisible to cameras and create site or artifact reconstructions, though even non-artistic archaeologists must draw basic sketches including plot maps of unit floor levels, profile walls, and locations of features and in situ artifacts/ecofacts. The most important aspect of any excavated artifact is its provenience—how it relates to other artifacts, features, and local geology—as knowing where an artifact comes from is absolutely essential for interpreting its meaning during analysis.
After completing notes, excavators collect lithics, ceramics, metals, bone tools, other animal bone, human bone, and other human-made or used objects in paper or cloth bags carefully labeled by context to track provenance for lab analysis, along with burnt wood or carbon samples wrapped in aluminum foil without hand contact to prevent contamination for radiocarbon dating, and soil samples from relevant contexts for flotation or specialized analyses. Collection criteria depend on project design and local standards, with field identification sometimes difficult—objects appearing as lithic débitage may prove to be unmodified rocks after lab cleaning—making it better to err on caution since unmodified rocks can be discarded in labs but artifacts left behind are lost forever, though archaeologists must consider storage in high-quality curation facilities for future research despite facility shortages. However, some objects cannot or should not be collected if they're too large to move, part of structural features that would lose integrity if removed, better preserved in situ than in labs/repositories, or must remain in place according to local or descendant community wishes for spiritual or political reasons, particularly in mortuary or religious contexts, with all collection decisions requiring adherence to clear archaeological ethics standards throughout excavation.
Ethical Considerations
Archaeological ethics governed by standards like the Society for American Archaeology's Code of Ethics (covering stewardship, accountability, commercialization, public education, intellectual property, publication, preservation, training, and safe environments) establish archaeologists' responsibilities to colleagues, the archaeological record, descendant communities, and students during excavation. We will consider ethical considerations in more detail in the next chapter. For now, here is a high-level overview of what archaeologists must keep in mind during excavation.
Field sites must be physically safe—avoiding dangerously deep units, preventing falls and tool accidents, maintaining first aid kits with knowledge of nearest health facilities—while addressing environmental hazards like heatstroke, frostbite, allergies, animal attacks, snake/insect bites, bacteria, parasites, hazardous waste, and unexploded ordinances, but also must be free from sexual harassment, discrimination, and assault, which surveys reveal are unfortunately common problems for female scientists and people of color in field-based sciences including archaeology's predominantly white discipline.
Stewardship requires preserving and protecting the archaeological record from looters and commercial interests by excavating judiciously only when learning more than preservation would provide or when preservation is impossible due to development or climate events, leaving portions unexcavated for future researchers with new technologies and questions, avoiding public sharing of exact coordinates unless sites are protected, properly curating and storing excavated objects, and never providing price estimates or engaging in commercial artifact activities.
Accountability to descendant communities and stakeholders is essential, particularly regarding human remains or religious sites, requiring coordination and collaboration with community members and landowners beyond state/national legislation, respecting that some sites should never be excavated and certain protocols may be necessary—even such as preparing offerings for rituals performed by community specialists before excavation, similar to agricultural or construction "earth-breaking" ceremonies. Many indigenous communities recognize land and landscape features as living community beings.
Archaeologists must share findings first with descendant communities and stakeholders, then the broader public through peer-reviewed journals, popular magazines, blogs, documentaries, webpages, outreach events, and open educational resources to combat pseudoarchaeology and educate the public, making comprehensive field notes valuable only when published rather than stored privately.
Finally, training new archaeologists requires safe practice environments since sites cannot be re-excavated—such as burying fake "sites" on campus for students to practice unit setup, excavation, and artifact mapping—though actual archaeological field schools taught over summers provide invaluable hands-on learning opportunities while earning college credits.
