"Archaeology: Basic Field Methods" by R. Michael Stewart
10 min read
The following is a summarized version of Stewart's Archaeology: Basic Field Methods prepared for my Academic Cooperative course at Austin Community College and first field session in Belize (Summer 2011). For convenience, here is the book citation:
Stewart, R. Michael. (2002) Archaeology: Basic Field Methods. USA: Kendall/Hunt Publishing.
As of 2022, this textbook summary also links to examples from my field experience (2011-2014), where applicable.
What’s the Point? (pages ix-xii)
Fieldwork is flexible. Without flexibility, archaeologists would be unable to address the past and its people with a variety of questions in archaeological deposits. It is difficult to learn when and how techniques should be used and there is no book that an archaeologist can open to address challenges; only experience combined with knowledge from books can build a framework for solving problems and making decisions.
Chapter 1: Basic Definitions and Assumptions (pages 1-16)
Archaeology, defined, is the means of studying the human past by analyzing material evidence and its context by the means of fieldwork. The goals and purpose of archaeological studies vary depending on the interests and theoretical perspective of the researcher. Bruce Trigger said, “changing social conditions influence not only the questions archaeologists ask but also the answers that they are predisposed to find acceptable.” Archaeology encompasses the details of everyday life, chronological sequences of events, as well as dealing with social and political aspects of the people studied.
By documenting archaeological finds, unknown pasts can be discovered. Material evidence (artifacts, ecofacts, and human remains) help archaeologists define material culture, the physical environment of the archaeological deposits, and a record of physical and social life. Context can be spatial, chronological, and behavioral; each give meaning to the artifacts – what was used, why it was used, and how it was used. Sites are where artifacts are collected in order to reconstruct past lifeways. There are ethical concerns: how archaeologists should behave in the field and elsewhere. Archaeological deposits are finite resources that must be excavated with a scientific plan or research design.
Chapter 2: The Archaeological Record and the Recognition of Evidence (pages 17-35)
How the Archaeological Record is Formed
Archaeological record is material evidence, its context, and the processes responsible for their creation and present condition. Cultural and natural processes both form and transform archaeological record.
Cultural processes are human behaviors that alter or transform a pre-existing material and/or context.
Natural processes create or transform the physical world and are responsible altering and destroying archaeological deposits. Not everything is preserved; in some sites material evidence is preserved while in others destroyed.
The archaeological record does not directly reflect human behavior; archaeologists must translate it into behavior through objective interpretation of evidence.
Preservation is conditioned by mechanical, chemical, and biological weathering. Depending on what the artifacts are made of and how they were made, the nature of the depositional environment, and the nature of the postdepositional environment, some things preserve better than others.
Preservation is enhanced by intentional or quick burial and/or the removal of materials from exposed surfaces. Modern life also impacts archaeological record: any alteration to the environment and alter archaeological record.
Recognizing Archaeological Evidence
Archaeologists constantly face the question, “Is this an artifact?”
The archaeological framework for identifying evidence consists of: analogs with things in our own culture; documentary and pictorial records; knowledge of ethnography, ethnohistory, and ethnoarchaeology; cumulative achievements of archaeology; experimental archaeology; natural and material sciences; and evaluation of context and associations (Stewart, 25).
Determining if something is natural or modified by humans is critical for accurately reconstructing the past.
Landscapes can be useful in determining where archaeological sites may be located. Studying cultures in the area, before and currently, amplifies knowledge about past lives that may have been responsible for creating sites or alterations present in situ.
Chapter 3: Fieldwork – Motivations and Design (pages 37-54)
Fieldwork consists of archaeological survey, site testing, and investigations focused on the research questions that drove the project to its initiation.
Collecting research and proper training is essential to a project before going out into the field.
Discoveries may be accidental and not always planned. It is important to understand the significance of a find before intensifying efforts in fieldwork.
Cultural resource management studies encompass areas that may be affected, transformed, or destroyed if the area of a site is altered. Generally, these studies are put in place before construction projects.
In the United States (USA):
- The National Historic Preservation Act established the National Register of Historical Places which lists areas and objects that have cultural or design values. To be listed the resource must be classified as significant at the local, state, or national level (e.g., the petrified forest).
- State Historic Preservation Officers (SHPO) oversee the preservation and management of listed resources.
- Tribal Historic Preservation Officers (THPO) are responsible for Indian lands and the Advisory Council on Historic Preservation (ACHP) advises the President and Congress on preservation matters.
Fieldwork consists of identifying and locating archaeological resources via research design: developing hypotheses, determining what data is needed to answer the hypotheses and how to collect the data, analyzing and evaluating the data collected, and ultimately answering the hypotheses or developing new ones that require further investigation.
Budgets limit how much work can be done on a site, making sampling a very important element. Samples provide information about where sites may be so more effort is placed in those of high and medium probability levels. After identifying known elements (structures, land features, previous sites), samples may be taken by qualitative (intuition) or quantitative (statistical) samples, such as random grid units and stratified samples in order to address the areas of high and medium probability.
Chapter 4: Background Research (pages 55-84)
In order to start a project, background research must be done on the culture, the history, the environment, and previous land use in order to create a context for evaluating the significance of sites discovered.
Cultural and historical background consists of analyzing history of the area, maps, projects completed in the area, previously located sites, and any prehistoric and/or historic developments in the local, state, region, or nation depending on the extent of the project.
SHPO keeps a record of documents about any site surveys that were previously carried out; these can be significant if the project is an expansion of a previous one (e.g., a previous project revealed a prehistoric home on one side of a hill, maybe another home is on the other side of the hill).
It is important to know who has already worked in the area, what has been discovered, how and where sites have occurred, and if any of these sites have been classified as significant for the National Register.
Environmental data is useful in formulating expectations about what kind of rocks may be encountered in a project area, distinguishing man-made landscapes from natural geological processes, identifying useful types of rocks for the inhabitants of the area, where the useful rocks came from, and the locations of quarries, rock shelters and caves might exist in the project area.
Geological maps, aerial photos, topographic maps, and soil maps can help further the team’s knowledge of the project area. These resources can reveal what resources were used by past people, where clay is located for pottery, how deep excavations will need to be, determining the age of a site (stratigraphy and soil weathering), and even enable the reconstruction of paleoenvironments.
How the landscape was previously used is a factor that should not be overlooked. Landscapes transform over time, and if the land has been used for farming artifacts may have been moved from their original context.
It is important for an archaeologist to prepare for what may be encountered once in the field so interpretations are correct.
Chapter 5: Preparing for the Field (pages 85-99)
Preparation for field work includes field kits, dress, health and safety concerns, and field etiquette.
Field kits may have some or all of the following: trowel, ice pick, gloves, root clippers, knife, compass, ruler and/or tape measure, plumb bob, line level, hand lens, soil Field Guide, personal provisions, and a Fieldbook.
- A trowel, pointed and 4.5-5 inches long, is used to move and cut through sediments. Some archaeologists carry a variety of trowels to make different types of work easier.
- An ice pick or stiff wire is used as a probe to find where large artifacts may be located or to get a feel for the stratigraphic boundaries.
- A knife is a multipurpose tool: cutting, chopping, testing soil compaction, or sediment texture.
- Root clippers remove roots for excavating, photographs, and mapping.
- Gloves are necessary to minimize cuts, scrapes, and blisters, plus protect your hands from oils of poisonous plants.
- A compass is for context and maps; rulers/tape measures are for measuring units and the sizes of objects.
- A plumb bob keeps the walls of an excavation straight and maps horizontal locations of objects; a line level records depth.
- A field guide, such as a Munsell color chart, describes and classifies soil color and texture. A 10X hand lens is used for examining sediments and the edges of artifacts.
- Personal provisions should include all personal information, emergency contacts, health insurance, medications, and allergies.
- A fieldbook is a daily log of anything and everything done and things-to-do next. Clothing should be professional, comfortable, adequate for the climate, and inoffensive to communities you may be working with, plus ankle-high boots and brimmed hats (or hard hats if working in hazardous zones).
(NOTE/TODO: I have a picture of my field kit from my second Belize field session. It should be added here.)
Personal safety includes having a health and safety plan, plus possible training for on-site safety measures, such as CPR. Field hazards may be part of the existing environment (insect bites or poisonous plants), the working environment (injuries or labor strains), or living in the field (personal hygiene).
Field etiquette is acceptable behavior and communication to your team and visitors about what you are doing and why.
Chapter 6: Map, Surveying, and Mapmaking (pages 101-160)
Maps are essential for planning prior to fieldwork so that once in the field members of the team have knowledge regarding the natural landscape, the rocks, plants, and soils that may be present, and be able to recognize out of place things in the landscape that are a result of human behavior.
Topographic maps record elevations, the rise and fall of the landscape, and cultural features. The most common map scale is the USGS 7.5 minute quadrangle (1:24,000).
In a map, the name, a key, a scale, and topographic contour lines are displayed.
Coordinate and grid systems used by archaeologists include latitude, longitude, degrees and minutes, and the UTM grid.
Topographic map symbols include water, cultural features, land surface, vegetation, unsurveyed areas, major roads, urban area, and added features from aerial photographs.
Surveying and Mapmaking
Various instruments are used to determine direction, measure angles, and do surveying. These instruments include, but are not limited to, magnetic compasses, GPS, and theodolites.
Distances are measured in a variety of ways, such as by measured pace (e.g., 12 steps equals 1m).
A compass is used to locate and plot the position of an area, its diversion from true north and its orientation on a map. Stewart uses the example of a site next to a lake and the site’s 40° angle from the Buck Road and Fort Road intersection.
Sites are documented with landmarks and GPS location.
UMT grid units are used to depict in which unit a site is located.
Transect lines are used to locate a general area for subsurface tests.
Grids and units are placed according to the site datum point by means of triangulation.
Plan maps and elevation for topographic maps are also part of the procedure.
At the end, a draft of survey data is constructed.
Chapter 7: Sediments, Soils, Stratigraphy, and Geomorphology (pages 161-204)
Geoarchaeology is the combination of studying soils, sediments, and the formation of landscapes.
Sediments reflect the color of parent material (Munsell Color Chart) based on hue (dominant spectral color), value (lightness or darkness), and chroma (strength of lightness/ darkness).
The size of grains is are graded with the Wentworth Grain Size Classification. Texture can be gravelly, cobbly, or stony.
Soil and sediment texture can be classified as sandy, loamy, silty, clay, or a combination of this four main textures. Consistence and stickiness is also characterized. Particle shape and orientation are also determined, and are sorted according to size.
Soil forms from a parent material and may receive additions that cause transformations: transfers (movement), translocations (movement and deposition in a soil column), and removals (extraction by soluble materials).
Color reflects the developmental process and texture reflects mechanical, chemical, and biological breakdown of materials.
Soil structure (how peds separate from each other) may be weak, moderate, or strong and described as granular, crumb, platy, blocky, subangular blocky, prismatic, or columnar.
Soil horizons are created by the processes that form soil: (i) O, organic matter, (ii) A, well-decomposed organic matter, (iii) E, mineral horizon zone of intense leeching, (iv), B, mineral horizon zone of illuviation, (v) C, unweathered and lacks characteristics of A and B horizon, and (vi) R, the bedrock.
Discontinuity is a break in the soil profile.
Stratigraphy is defined by the law of superposition (the highest is the youngest and the lowest is the oldest).
Geomorphology is the study of how landscapes are shaped.
Two features that result from shaping processes are flood plains (table 7.4) and slopes (table 7.5).
Samples are taken in consistent vertical increments. Soil must be interpreted based on the effects of climate, organisms, topography, and parent material.
The Harris Matrix is a way to organize stratum into a schematic diagram.
Chapter 8: Working on the Surface (pages 205-237)
Archaeological deposits are generally during the first step, surface survey.
Factors that can affect discovering artifacts include abundance, clustering, and obtrusiveness of artifacts, visibility and accessibility of the site.
Surface observations include topography, vegetation, drainage, sediment and soil color, above-ground construction, and artifacts.
There are multiple types of exposures and disturbances that can be looked for and examined; some of these are trails, areas of construction, and arid environments with little vegetation. Signs of deposits that were once-buried are: “tight spatial clustering of artifacts, human remains, and patterned soil discolorations.”
Field notes should include field observations (table 8.4), the activities performed, why they were performed, the field conditions they were performed under (can affect the reliability of survey results), the results produced, how the results were interpreted, the relevance of the survey to the research design, and how future action should follow.
All artifacts and samples collected are listed in a field specimen catalog (figure 8.29) and photographs of the methodological work recorded in a photo log (figure 8.32).
The location, size, and shape of surface features and recovered objects should be recorded with their provenience.
Remote sensing techniques (e.g., aerial photography, ground penetrating radar) have provided ways for non-invasive archaeology to grow. Now archaeologists do not have to expose a site until invasive archaeology is needed, therefore increasing the preservation of a site.
(NOTE/TODO: link remote sensing to Alaska project)
Chapter 9: Subsurface Investigations (pages 239-318)
Subsurface excavations require special excavation tools, such as digging tools (shovels), screening devices for dry screening (typically ¼ inch or ⅛ inch, size depends on the size of artifacts being recovered) or wet screening (break down sediments and soils), augers (drill into sediments for sample collections) and coring devices (vertical subsurface samples), and sometimes earth-moving machinery (e.g., backhoes, bulldozers, grandalls).
Unit dimensions are 1x1 meter, 5x5 meter, etc. The type of excavation determines unit size.
Excavations may be by natural strata, arbitrary levels in a natural strata, only by arbitrary levels, or by quadrants. Stratum and levels are labeled and reflected when recording provenience (e.g., site, unit number, stratum, level/quadrant/artifact).
First a unit is measured and elevation is recorded below datum (BD).
Materials recovered should never be mixed with different levels or contexts in the screen.
Artifacts should try to be located in situ before the screening so exact provenience can be recorded; once in the screen only the level in the unit is known.
Artifacts are plotted in a unit map (a mapping screen may be used for determining an exact location) that is scaled.
Before a new level is begun, the level is given a catalogue number for the next batch of field specimens.
Excavations are affected by the excavation size, depth, number of, and distribution of excavations.
Field records include provenience tags or cards, excavation level forms, an excavation summary form, feature level and summary forms, and the artifact collection. If a burial was discovered, a burial recording form is also submitted.
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