Principles of Excavation

What is Archaeology?

• A subdiscipline of anthropology. Anthropology is the study of humankind.
• Archaeology is the study of the human past through material remains.
• Material remains are collectively referred to as the archaeological record. This includes artifacts (e.g., stone tools, ceramic vessels); features (e.g., housepits, hearths); and ecofacts (e.g., animal bones, plant remains).
• Archaeologists have three main goals:

1. Reconstruct Culture History: understand the distribution of archaeological remains through time and space.
2. Reconstruct Past Lifeways: determine past behavior through material remains.
3. Explain the Process of Culture Change: understand how and why cultures change through time.

• Artifacts: portable objects whose form has been created or modified by human activity (e.g., projectile points, pottery vessels). Artifacts retain their appearance after the archaeologist takes them from the ground.
• Features: non-portable artifacts that cannot be removed from the ground without altering or destroying their original form (e.g., housepits, burials, hearths).
• Ecofacts: non-artifactual material remains that are not directly created or modified by human activity but have cultural relevance and provide information about past human behavior (e.g., animal bones, sediment, pollen).
• Sites: spatial clusters of artifacts, features, and ecofacts. Sites identify where humans have occupied the landscape (e.g., Birch Creek, Stonehenge).
• Regions: the largest definable spatial clusters of archaeological data. Regions can be a geographical, ecological, or cultural concept. Definition of a region allows the archaeologist to investigate a wider range of past activities that extend beyond a single site (e.g., Great Basin, Columbia Plateau, Southwest).

• Archaeologists use the deductive scientific approach.
• Form a Hypothesis: Ask a question that can be tested through observation.
• Test the Hypothesis: Collect data through observation.
• Accept or Reject the Hypothesis based on collected data.
• A research design is a systematic plan that ensures that archaeological research is organized, efficient, and valid.
• Seven Steps of an Archaeological Research Design:

1. Formulation of Research: Defining a research problem. Background research is usually conducted to refine the research problem. Defining a research problem also indicates where to look for archaeological data and what types of data to collect.
2. Implementation of Research: Involves all arrangements necessary to conduct fieldwork. These types of arrangements can include obtaining permission to carry out field research, raising funds to finance the research, acquiring equipment and supplies, and recruiting staff members and excavators.
3. Data Acquisition: Acquiring archaeological data.
1. Archaeological Reconnaissance: locating and identifying archaeological sites.
2. Surface Survey: recording as much as possible about sites without excavation. This often includes photography, mapping, probing, and surface collection of artifacts.
3. Excavation: uncovering and recording a buried archaeological site.
4. Data Processing: Collected archaeological material must be processed in the field. Data processing involves cleaning, numbering, cataloging, drawing, photographing, and taking notes of the archaeological data.
5. Data Analysis: Data analysis is usually conducted in a permanent laboratory after fieldwork is completed. Some types of data analyses include:
1. Artifacts: classification, technology, function.
2. Chronology: age determination through absolute and relative dating techniques.
3. Faunal Remains: identification of animal species.
4. Floral Remains: identification of plant species.
5. Geological Analysis: sediment analysis.
6. Data Interpretation: The synthesis of all the results of data collection, processing, and analysis in an attempt to answer the original research question. Interpretation enables the archaeologist to reconstruct and explain the past.
7. Publication of Results: The data, data analysis, and interpretation are published. Publication allows the research and its results to be used and retested by other people.

• The archaeologist must know her or his location in three-dimensional space in reference to a known point.
• Horizontal Provenience: Site datum and site grid.
• Datum: The site datum is a known location in three-dimensional space that serves as a reference point for all horizontal and vertical measurements taken at the site. The datum is a known point in three-dimensional space, but it is entirely arbitrary.
• Grid: The site grid is laid out in reference to the datum. When referring to grid units, the coordinates of the SW corner of the unit are used.
• Total Station (a.k.a. EDM, transit, theodolite, the instrument): A total station is a survey instrument that can measure horizontal and vertical angles, slope, and horizontal and vertical distances. The total station is another piece of equipment that archaeologists use to know their position in three-dimensional space. Measurements recorded by the total station will produce an x, y, and z value. The x-value represents the northing, the y-value represents the easting, and the z-value represents the elevation.
• Birch Creek Site Datum and Grid
• The site datum at Birch Creek is located to the south of the housepit block. The coordinates of the site datum are N1000 E1000.
• All units are referred to with a northing and an easting coordinate, and all measure 1 meter square.
• Units located to the north of datum have a northing greater than 1000, and units located to the south of datum have a northing less than 1000.
• Units located to the west of datum have an easting less than 1000, and units located to the east of datum have an easting greater than 1000.
• Vertical Provenience
• Vertical measurements will also use the site datum as a reference point.
• The elevation of the site datum in three-dimensional space is z=1000.
• All levels will be recorded in reference to the datum point, but a few steps are needed to get the elevations.
• During excavation, a laser level will be used to take vertical depth measurements in the excavation unit.
• The laser level sends out a signal that creates an invisible horizontal plane across the site. The excavator will slide the laser level up and down the pole in order to locate the laser level signal.
• When the receptor is close to being inline with the horizontal plane it will beep repeatedly. When the receptor is directly inline with the laser signal it will make a constant ringing sound. Using the measurements on the laser level rod, a 3-meter tape is used to measure the depth of the unit below the laser level.
• Each morning after the EDM is set up, a shot will be taken of the laser level. The elevation of the laser level will be used to determine the depth of the excavation level below the site datum.
• Example 1
• Excavation level is 75-80 cm below the laser level.
• The elevation of the laser level is z=1001.15. The laser level is 1.15 meters, or 115 cm, above datum.
• Subtract the depths of the excavation unit (75-80 cm) from the elevation of the laser level (115 cm).
• The depth of the level is 40-35 cm above datum.
• Datum has an elevation of 1000; add the new values (40-35 cm) to the elevation of datum.
• The excavated level elevation is z=1000.40-1000.35.
• Example 2
• Excavation level is 150-155 cm below the laser level.
• The elevation of the laser level is z=1001.15. The laser level is 1.15 meters, or 115 cm, above datum.
• Subtract the elevation of the laser level (115 cm) from the depth of the excavation level (150-155 cm).
• The depth of the level is 35-40 cm below datum.
• Datum has an elevation of 1000; subtract the new values (35-40 cm) from the datum elevation.
• The excavated level elevation is z=999.65-999.60.

• Triangulation is a technique that enables archaeologists to lay out grid units using a pre-established baseline. Triangulation will be used to set up new excavation units at the Birch Creek Site.
• The Pythagorean Theorem states that the sum of the squares of the legs of a right triangle is equal to the square of the hypotenuse. There is a table of commonly used triangulation values on your cheat sheet.
• To create a 1-meter-square unit, 2 points must be known on the baseline that are 1 meter apart.
• Use two separate tape measures: one tape will be used to measure a distance of 1.00 meters, and the second tape will be used to measure a distance of 1.414 meters.
• Two people will hold the ends of the tapes on the two points on the baseline; a third person will extend both tapes to intersect the 1.00 m and 1.414 m marks.
• The position where the two measurements intersect becomes the location of the third corner of the unit. The same steps are used to position the fourth corner of the unit.
• Be sure to double-check the position of the nails, both side-to-side and diagonally.

• Archaeologists do not excavate each unit in its entirety, and excavation proceeds by systematic levels or depth intervals.
• Four different methods include:

1. Natural or Stratigraphic Levels: Excavation reverses the natural order of deposition at a site by proceeding downwards one stratum at a time. Soil color, texture, and content are used to define different depositional levels.
2. Contoured Arbitrary Levels: The archaeologist picks an arbitrary depth (5 cm, 10 cm, etc.) to which the entire unit is excavated, paralleling the natural slope of the ground surface.
3. Simple Arbitrary Levels: Levels are defined by arbitrary depths below datum. When a level is completed, all four corners and the center of the unit will be the same depth below datum.
4. Combined Natural and Arbitrary Levels. Using both natural and arbitrary levels can be a flexible and practical method depending on the stratigraphic levels present in the unit.

• A Constant Volume Sample (CVS) will be taken for every level excavated at the site. A CVS enables archaeologists to find tiny artifacts (e.g., flakes, fish bones, seeds) that would normally pass through the 1/8-inch mesh used for screening.

• The most common archaeological tool is a mason's trowel.
• Troweling permits maximum recovery of in situ finds and probably does the least damage to fragile items.
• Troweling, combined with the complete screening of all backdirt through an 1/8-inch mesh screen, is a careful and precise excavation method.
• General Excavation Guidelines:
• When you encounter something in digging, STOP! Do not remove the object, but carefully excavate around it looking for possible associated materials.
• Keep your unit walls vertical and corners at a true 90 degrees.
• Do not remove artifacts from sidewalls. If the artifact is not removed during the removal of a level, leave the artifact in the wall.
• When troweling, keep the trowel edge at a low angle to the ground. This helps to prevent gouging the floor of your unit.
• Keep the floor of your unit as level as possible when excavating.
• Keep your unit clean. Avoid large piles of backdirt; it is difficult to see what is happening in your unit if too much backdirt accumulates at the bottom.

• Sifting excavated earth through screens enables the archaeologist to recover many materials that might otherwise be overlooked (e.g., tiny flakes, animal bones).
• All backdirt will be screened. Screens of 1/8-inch mesh will be used at the Birch Creek Site.
• Don't dump out the material in your screen until we are confident that you know how to identify artifacts.

• Because the archaeological record is destroyed through excavation, it is extremely important that detailed notes are taken throughout the excavation process.
• General Note-Taking Guidelines:
• Do not avoid recording information because of unfamiliarity, laziness, bad weather, etc.
• Be honest in note-taking. Don't be ashamed of admitting to, and noting, mistakes or inadequacies in your previous work. It is better to record mistakes and learn from them than to let errors accumulate.
• Take the time to keep all notes complete and up to date. Take notes throughout the day, and at a minimum include in your notes all the information recorded on level forms. Don't be afraid to include your own ideas about what might be going on at the site.
• Be accurate, consistent, and specific in your observations. Use "25 cm" instead of "20-30 cm"; use descriptive terms consistently and specifically; don't guess at measurements.
• Keep your records, drawings, and labels neat, clean, and legible. People will be using the information you record.
• Plan View and Profile: Plan view maps and profile maps are an important part of the note-taking process. A plan view is a map of all significant features, artifacts, ecofacts, etc., drawn for each level of every excavation unit. Profile drawings are accurate vertical maps of the stratigraphy, artifacts, features, etc., exposed in the walls, or "profiles," of excavations.