Columbia Archaeology Program Guide to Field Methodologies

A GUIDE TO ARCHAEOLOGICAL FILED METHODOLOGIES

CONTENTS A. B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. Q. R.

Site Numbering Measurements Grid Basics Elevations Soil Descriptions Photography Recording Conventions Sampling Survey Shovel Test Pits Excavation Maps and Drawings Screening Conventions Field Bag Procedures Handling artifacts in the Field Identifying Excavated Materials in the Field Keeping Artifacts Wet or Dry Public Archaeology

A.

SITE NUMBERING

The trinomial site numbering system was developed by the River Basin Surveys of the Smithsonian Institution and is the standard used for all archaeological sites in the United States. The site number consists of three parts. The first two digits refer to the state and are numbered alphabetically (e.g. 38 = South Carolina). Since the system was developed before Alaska and Hawaii were states, these states are out of sequence and appear at the end. The second part is a two-letter county abbreviation (e.g. RD = Richland County), which is always written in capitals. The third part is the site number. Site numbers are assigned sequentially in the order in which they are identified (e.g. the Mann-Simons site was the 1,083 site identified in Richland County). Site numbers do not indicate if a site was excavated, only that it was identified as an archaeological site. In South Carolina, site numbers are assigned by the South Carolina Institute of Archaeology and Anthropology, a joint department between the University of South Carolina and the State of South Carolina.

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B.

MEASUREMENTS

All archaeological measurements, both for grid and elevations, are made using an engineer’s scale of feet, tenths, and hundredths. When measuring architectural features (e.g. structures, post molds, etc.), measurements should also be made in feet and inches because of the cultural relevance of these dimensions. Because of potential errors, it is not acceptable to use metric measurements and then convert them.

C.

GRID BASICS

The site grid is established in order to record the location of STPs, excavation units, and as an aid in mapping.

Laying out the gird begins with identifying a single point on the site known as the datum. A grid line running north to south is established off of this point, identifying the northing coordinate. An intersecting grid line is established 90 degrees east to west off of this line, identifying the easting coordinate. Coordinates are designated in terms of their north/east location relative to the datum point and are written as N________ E________. The first number is always the north point and the second number is always the east point, separated by a space. North values increase to the north and east values increase to the east.

An arbitrary datum and grid system was established for the 1998 excavations, which we continue to use to ensure comparability of data between projects and field seasons. The grid system at the site is oriented to the Columbia street system, which is 14°-24’ west of magnetic north. To avoid confusion, north is always referred to as ‘grid North’ (abbreviated ‘gN’) on all maps, notes, forms, etc. The permanent datum at the site consists of a three-foot length of ½ inch rebar driven flush with the ground near the Marion Street sidewalk. This datum point was assigned an arbitrary coordinate of N500 E500 and an elevation of 100 feet. This ensures that we never have negative numbers, since the site boundaries are less than 500 feet in any direction from the datum point. A good way to remember which way is north is to remember that the tall apartment building is north of the site.

Temporary datum points are established at the site as needed, since not all areas of the site are visible from the permanent datum point. Each datum is given an official name, such as ‘Temp Datum A1’ and, along with its horizontal and vertical coordinates, recorded in the master survey book. The datum point from which the new temporary datum is established should also be recorded. That way, if measurements are consistently off, we can better determine where the error is coming from. Temporary datum points are generally spikes driven nearly flush with the ground. A length of colored flagging tape is tied directly below the head of the spike and labeled with a Sharpie. The label should list the name of the datum, horizontal coordinates and elevation. A pin flag should be placed near the datum point to help ensure that the nail can be found again and reduce the likelihood of it being stepped on.

D.

ELEVATIONS

Elevations are expressed, as are other measurements, in feet, tenths and hundredths. Elevation readings are done by transit and/or string lines. For each discrete provenience, elevations are recorded on the provenience form (see example) and must include the datum point from which the measurement was taken. Opening and closing elevations must be recorded for all layers and features. When recording elevations for layers within excavation units, measurements are taken near the northeast, northwest, southeast, and southwest corners, as well as the approximate center of the unit. In addition to the provenience form, all elevations should be recorded on any maps you draw. Take extra readings for the plan drawing when you need to show an irregular surface or feature. If elevations are taken not

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related to excavation (e.g. mapping site boundaries), these should be recorded in the master survey log as well as on any documents being produced, e.g. maps. Check your numbers! Do your readings make sense given previous or nearby readings?

E.

SOIL DESCRIPTIONS

Accurate and detailed soil descriptions are vital for linking the stratigraphy between excavation units and for allowing future researchers to effectively assess the context of the artifacts and to understand the excavations. Each soil being described must be from a freshly cut surface and must be moist. It must be described using a Munsell soil color chart and will include the color name, hue, value and chroma. Descriptions must also include a texture description. Soils are seldom only one color but usually a mixture of colors and textures. The mottling present in a soil must be described in the same way and must include an estimate, expressed as a percentage, of how much mottling is present.

It is important to know what materials (e.g. gravel, brick, charcoal, etc.) are contained in the soil and the frequency of these must be estimated. All of these elements need to be put into a standard format. The first soil described is the dominate soil type/color. For example: Dark yellowish brown (10YR4/4) sandy loam, mottled with 20% yellowish brown (10YR5/6) clay loam, 5% gravel, 2% brick, <1% charcoal.

Please see Gregory Vogel’s “Handbook of Soil Description” for a detailed description of soil analysis.

F.

PHOTOGRAPHY

Photographic documentation of all phases of archaeological investigation is essential. Subjects to be recorded include general views of the site, work in progress and detailed record shots. Any provenience where features or uneven layers are showing needs to be photographed. For comparison purposes, stratum photos should be taken from the south whenever lighting or physical conditions permit. If this does not show important details clearly, do an additional shot from another side. After a unit has been completely excavated, a photograph of the profile must be taken.

Photograph the profile as nearly level and square-on as possible. If it is impossible to photograph the entire profile with one exposure, take more than one shot and overlap them. All excavated features are to be photographed in detail before excavation, during excavation, and after excavation. Each record photograph must include a trowel (oriented with the point to the north) or north arrow and a scale. Clean the unit for photo with a sharp trowel (no foot prints or loose dirt). Photos are taken before doing soil descriptions, taking elevations, and drawings. Photographs show much more detail if taken on a cloudy day or in artificially contrived indirect lighting (e.g. shading with plastic sheeting). To enhance color contrast, you can dampen the area with a hand sprayer filled with water.

It is important to maintain a detailed photographic log, which includes the photo number (sequential numbering), the date the photograph was taken, the area and orientation of the shot, the subject matter (e.g. “top of Feature 6F, post mold”), the negative or slide number, and if any filters were used. The photographic record is as vital to understanding the site as the paper records and a complete set of slides and negatives need to be curated with the other records. To maintain consistency, one individual will be designated as site record photographer. You are encouraged to bring your own camera to record your work and take photographs of the site.

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G.

RECORDING CONVENTIONS

The need to provide for future research opportunities at the site and use of the materials requires not only careful attention to recording the data but also how it is recorded. Note taking is one of the most important things you do as an archaeologist. You will often spend more time taking notes and drawing maps than actually digging. Your notes must be legible, concise, and informative. Donâ&#x20AC;&#x2122;t assume that future archaeologists who read your notes will know what your assumptions were unless you clearly explain them. Recording your impressions and initial interpretations are just as important. You are not just digging, but constantly interpreting what you find and modifying your strategy based on these interpretations. No one will ever know the unit you are working in better than you.

The record keeping system used at the Mann-Simons site is form based in order to assure similar data being recorded for each excavation unit. Most important of these forms are the 1) provenience sheet, 2) stratum register, 3) field photograph log, and 4) artifact control card. Examples of the forms are discussed in other sections. All of the forms need to be copied on acid-free, bond paper and completed in pencil. The standard drawing material is a prepared tracing paper, 15 in. by 16 in., with a blue line grid of 10 squares to the inch. All stratum, feature, and profile drawings are to be done at a scale of 1 in. = 1/2 ft., while full site maps are done at a scale of either 1 in. = 10 ft. or 1 in. = 20 ft. Drawings are to be completed only with a mechanical pencil using a 0.5mm lead.

H.

SAMPLING

Sampling acts as a measure of the validity of inferences, where inference depends on the sample observations being representative of the entire sampling area (the bounded area under investigation). Sampling is about inferring from a portion of an archaeological site to the whole of the site, it is not about inferring from the sample to past human behavior. There are two broad ways in which an area may be sampled; the first is through non-probabilistic (contextual) sampling, while the second is probabilistic (statistical) sampling. The emphasis of non-probabilistic sampling is usually on the presence or absence of attributes, materials, features, or sites. Non-probabilistic sampling is non-comparative, in that there is no statistical means of comparing two groups of samples. Probabilistic sampling is designed to generate samples that are statistically representative and comparative. This generally means creating a random sample which can be done in four ways: simple random sample, systematic random sample, systematic unaligned sample, and stratified random sample (Fagan and DeCorse 2005).

A simple random sample is a totally random sample selected from the entire area under investigation. Usually, the area under investigation is divided into a series of equally-sized squares and numbered sequentially. A random number table is then used to select the sample based on the proposed sample size expressed as a percentage. A systematic random sample is where the first unit is selected randomly, but all other units are selected in relation to this first unit (e.g. we might select every fifth unit based on the location of the first unit). A systematic unaligned sample is when an area is divided into equal, large blocks and then within each block a smaller one is selected at random. A stratified random sample stratifies the target area into classes; each considered an independent area in which a random sample is taken. Class definition can be arbitrary or based on difference (e.g. environmental zones or functional/activity areas) (Fagan and DeCorse 2005). The advantage of this method is that it ensures that all areas are sampled from and is the sampling method most often employed at the Mann-Simons site.

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I.

SURVEY

Field work is to be regarded as comprising three phases: 1) survey followed by 2) testing followed by 3) excavation.

Archaeological survey is a reconnaissance of land surfaces for evidence of prehistoric or historic occupation. This manual is not the place to discuss the many complexities of survey sampling design, matters that are confronted and refined in the course of research design development. In brief, there are two types of survey strategy, the reconnaissance survey and the intensive survey. The goal of reconnaissance survey is to gain initial field-based estimates of the archaeological record, and to determine the most appropriate survey techniques for the region of study. The goal of intensive survey is to systematically sample the target area, and generally falls under three categories: pedestrian survey, sub-surface survey, and remote sensing. A pedestrian survey involves a systematic walk over the target area, usually carried out along transects, visually looking for archaeological materials or their indicators. A sub-surface survey involves the digging of test holes (usually shovel test pits, discussed in the next section), screening the dirt, and recording the stratigraphy and artifacts. Remote sensing uses non-invasive instruments, such as grand penetrating radar or electrical resistivity meters, to reveal deviations from the homogeneity of the soil matrix.

J.

SHOVEL TEST PITS

Shove test pits (STP) are small-scale excavations dug with shovels at regular intervals across a site. Each STP is labeled based on the North and East coordinate on the grid. They are designed to be quick tests of the subsurface area of a site. STPs are dug as square 1x1 foot holes (large enough to observe stratigraphy and materials as well as get the shovel in as you dig deeper) with a square-mouthed shovel. These will be dug using natural levels. STPs are recorded on a form designed specifically for this type of testing. One (1) form is used for the digging of each STP regardless of the number of levels. The form asks you to record the STP number (assigned by a supervisor), date of excavation, horizontal location, opening and closing elevations, a brief description of the soil, if photographs were taken, and comments regarding types of artifacts found. If no artifacts are found, please note this. The form also asks you to draw a profile map of the shovel test in the graphing section provided and to note the orientation of the drawing. An artifact control card (discussed in another section), the top of which is filled out completely in the field, is placed in a small plastic bag which is then placed within each artifact bag. This artifact control card will subsequently be used to record by whom and when artifacts are washed, sorted, and cataloged. We need to distinguish between STPs and Units, so if you are digging an STP, please be sure to record this on all cards and forms, using the designation ‘STP’.

K.

EXCAVATION

Units are dug as distinct areas of excavation, usually placed after testing has revealed features or areas of interest.

These are done in 5 ft. by 5 ft. square units in an effort to maximize spatial distribution data. Each unit has an identification number in addition to the coordinates of the site grid. Unit identification numbers are identified sequentially in the field. These numbers are assigned by a supervisor and recorded on the master site map and the stratum register. A unit’s designation is its southwest corner coordinates, written N______ E______. Corners of the unit will be marked with spikes. At the southwest corner, a length of colored flagging tape is tied directly below the head of the spike and labeled with a Sharpie. The label should list the unit’s identification number and grid coordinates (e.g. ‘Sq. 6, N445 E580’, where ‘6’ is the unit’s identification number). If you are ever unsure of your unit’s identification number, check the master site map.

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Unit Layout The actual layout of the excavation unit requires the setting of two grid points with the transit, representing corners of the 5x5 foot square. One of these two points should always be the southwest corner. The excavation unit can then be triangulated from those points (see page 20 of “Archaeological Surveying and Mapping” for a description of how to triangulate a unit). The southwest corner must be set with 4-inch nails or spikes, but other corners are set with duplex or forming nails. Pound the nails in until only a quarter of an inch sticks up. Brightly colored string is used to define the unit. Tie the string onto one nail, then wrap once around each of the next three nails. Now you can pound the nails flush with the ground.

Excavation Methods There are a number of general excavation techniques, the most common being shovel scraping (i.e. ‘schnitting’) and troweling. With practice, shovel scraping is an efficient method for removing dirt quickly without sacrificing data integrity. To shovel scrape, the excavator holds a sharpened flat-mouthed shovel so the blade will cut though a thin slice of dirt. During shovel scraping, the surface should be kept level: do not dig deeply into one area and then bring the other areas to that depth, as you are likely to miss layer transitions and disturb artifacts. Instead, a thin layer at a time should be removed across the entire unit. It is important to pay attention to the feel the dirt and listen to the sound of the scrape. Never scrape right up to the edge of the unit’s wall – leave several inches of buffer so you will not accidentally cut into the wall.

Troweling is the ideal method for creating a clean, level surface for photography, mapping, identifying features, and working around fragile artifacts. The angle of the trowel relative to the surface is critical for creating a clean surface and not smearing the dirt. The idea behind the trowel, as with shovel scraping, is to cut though a thin slice of dirt.

You do not want to use your trowel as a shovel and dig the dirt out. Nor do you want to scrape the surface. A good way to think about troweling is to imagine you are shaving the surface of the unit—in the same way you would not drag a razor blade perpendicularly across your skin, you don’t want to drag the trowel perpendicularly across the surface of the unit. It is important that you maintain a sharp, flat edge on your trowel. Good trowel work is essential for archaeology. The development of trowelling techniques is a primary goal of the field school.

Maintain a level floor as you dig so you can more easily see features and soil changes. Working one quadrant at a time may help you pinpoint artifact concentrations. Artifacts and rocks embedded in the surface of the stratum below the one just dug should be left in place – they belong to the level below. Similarly, be sure to leave all but the smallest artifacts in place until they are completely exposed. Keep profiles (walls) straight and clean as you dig, and watch for spots that are dry and likely to collapse. When excavation of a layer is complete, the floors and walls should be troweled down so that any features and new layers can be seen, drawn, and photographed. Take care not to back into profiles (walls) or gouge them with a shovel handle or bucket. Also, don’t stand or sit on the edges of the units – they crumble easily.

Stratigraphic Excavation Each stratum and feature will be dug separately. All excavation is to be conducted by natural stratigraphic layers. All strata are excavated in the reverse order in which they were laid down. The last stratum deposited must be the first excavated. It is particularly important that all intrusions be excavated first before the strata or features which they intrude. Strata and features are distinguished by differences in color, texture, compactness, inclusions of rock, gravel,

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cinders, charcoal, coal, etc. Recognizing stratum transitions and features takes practice, so check with a supervisor whenever you feel something should be designated as a feature or a new stratum.

Each unique provenience (e.g. stratum, interface, feature, etc.) is assigned a separate and unique provenience designation and gets its own provenience form. This will consist of the number of the square in which it occurs and a letter specific to that provenience. Provenience designations are assigned in the order in which they are encountered, e.g. if the unit number is 6, then the first layer is 6A, the next 6B, if a feature is next encountered, it would be 6C, and so on. If provenience assignments use up the entire alphabet, double letters are assigned, such as AA, BB, CC, etc. Because of their confusion with other letters or numbers when written on small artifacts, the letters I, O, Q, U, V, and Z are not used for provenience designations.

For each provenience letter assigned, three records need to be created or updated: 1) the stratum register, 2) a provenience sheet, and 3) an artifact control card (one for each bag of artifacts). A stratum register must be kept for each 5 ft. by 5 ft. square. The short title for a provenience must either be descriptive of the function of the feature (e.g. post hole) or descriptive (e.g. ‘Level 1’, ‘Circular Intrusion’, ‘Charcoal Lens’, etc.). The short title is also recorded on the provenience sheet, the artifact bag, and on the artifact control card. Start filling in the appropriate forms before you dig, including opening elevations, datum, and soil descriptions. Short titles are assigned by a supervisor.

The most important record is the provenience sheet. A separate provenience sheet must be filled out for each letter assigned in the stratum register. The provenience sheet asks you to record the site number (38RD1083), the project name (Mann-Simons), the area (unit identification number), the provenience letter, the date of excavation, the horizontal location (southwest corner of the square), and the opening and closing elevations. The upper right hand corner has a place for a location sketch and should be used to show all of the features in the square at that level. The feature being excavated should be shaded on the drawing. North should be the top of the sketch, and a north arrow should be drawn to indicate such. The stratigraphic definition of the provenience should be filled out completely and accurately (see ‘Soil Description’ section).

The provenience form also asks you to record any features associated the provenience. This is very important. If the provenience sheet is for a stratum, list all of the features encountered at the top of that particular stratum. If the provenience sheet is for a feature, under ‘Feature Association’ write “top of feature _____ at top of stratum _____”.

For example, “top of Feature 6C (post mold) at top of stratum 6B (Level 2)”. In the field it may seem redundant and unnecessary to spell this out, but it is very useful for recreating the depositional sequence once back in the lab.

Additionally, list any diagnostic or unusual artifacts (if nothing is collected, say so), and describe your observations, interpretations, and impressions, e.g. hypotheses about feature type, possible relationships between features, differences in soils, general observations, etc. You cannot say too much in your notes—the most mundane field observations are often the most important (and elusive) details during interpretation. Note with a check mark on the appropriate line if photographs were taken or any maps drawn. Finally, record the initials of all individuals involved in excavation as well as the initials of the recorder.

Feature Excavation Features are physical and immovable aspects of a site, such as post holes, fence lines, and foundation walls. Features, unlike artifacts, are not removable from the site and therefore must be excavated and recorded meticulously. Typical feature excavation proceeds as follows. After carefully cleaning the feature and surrounding area with a trowel and taking the necessary photographs, a cross-section line is established along the long axis of the feature. Elevations are

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taken and a plan view map of the feature is drawn. Work then proceeds by carefully excavating one half of the feature. Next, photograph and draw the cross-section (profile) of the feature using a string line (discussed in section ‘M’). The other half of the feature is then excavated, photographs taken, and a new plan view drawing completed.

The artifacts and material recovered from the two halves are kept as separate proveniences.

L.

MAPS AND DRAWINGS

Two types of drawings are typically made at an archaeological site: plan view drawings and profile drawings. As previously stated, the standard drawing material is a prepared tracing paper, 15 in. by 16 in., with a blue line grid of 10 squares to the inch. All plan view and profile drawings are to be done at a scale of 1 in. = 1/2 ft. (i.e. each small square on the paper = 1/2 inch), while full site maps are done at a scale of either 1 in. = 10 ft. or 1 in. = 20 ft.

Drawings are to be completed with a mechanical pencil using a 0.5mm lead.

Profile drawings are made of the strata observed in the walls of each square. A sample profile drawing is found in the ‘Examples of Forms” section. The number of walls to be drawn depends on the stratigraphy unique to that square. In general, the profile of the north wall is drawn, but if the strata appear differently in other walls then those walls are drawn as well. Title information appears in the upper right corner. The grid points, between which the section is drawn, are shown and the edge of the actual face exposed is indicated. Each stratum and feature is labeled according to its official provenience designation (e.g. 6C, 6F, etc.).

Profile drawings are most easily done with two people, one to take the measurements and one to do the drawing.

Equipment you will need includes: graphing paper, pencil, a ruler, two nails connected with a 5+ foot piece of string, a string line level, two tape measures (one metal and one folding rule is best), and a trowel.

The datum line represents a level string line of known elevation. To set up a string line, place the two nails in the ground on either side of the square flush with the profile to be drawn. Make sure the sting line connecting the nails is tight. Hang the line level from the string in the center and gradually adjust the height of the nails on either side until the sting is level. The elevation of the string line is made using the transit. Be sure to draw and label the string line on the map. All vertical measurements will be made from this string line. It is critical that the measurer have her eye level with the string when reading measurements.

A tape stretched between the square’s grid points (corner nails) enables horizontal distances along the section to be measured. Descriptions of the strata observed and drawn are given beneath the drawing. Generally, the zero end of the tape is centered over the head of the corner nail to your left. Begin with the ground surface, floor surface, and the walls, followed next by the individual strata. Once all the strata are drawn, draw and label inclusions within strata, for example, mottling, artifacts, rocks, brick, charcoal, mortar, roots, gravel, etc. Try to draw the general shape for larger inclusions, and use standard map symbols for all others (see example). Be sure to provide a key on your drawing.

Refer to an existing map or ask a supervisor when in doubt.

Profile drawings for features are produced in the same manner as unit profiles. After completely excavating one half of the feature (see ‘Feature Excavation’ section), establish a string line by placing two nails connected by a string in the ground on either side of the feature in line with your feature bisection line flush with the profile.

Plan view (top down) drawings follow the same conventions as the profile drawings. Plan views are only drawn for stratums containing features or a significant pattern of artifacts. Begin by drawing the square to scale on your

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graphing paper. Be sure to orient your map correctly: north is always toward the top of the page. To ensure accuracy, we generally use the transit for plan view drawings. This usually requires three people: one to operate the transit and call out readings, one to hold the reflector/prism, and one person to do the drawing. You should establish beforehand the order in which the person doing the drawing wants the coordinates called out (e.g. north first and then east). In cases where it is impractical to use the transit, tapes will be established along one or more edges of the unit (similar to the profile drawing) and a separate tape is held horizontally. It is very easy to introduce error using this method, so please be careful that the tape is always square to the unit. If the unit is very deep, a plumb bob used in conjunction with the horizontal tape is needed to take accurate measurements.

M.

SCREENING CONVENTIONS

All excavations must follow the same screening method to maintain consistency and comparability. Screening is performed through 1/4 inch wire mesh on all dirt dug from both STPs and units. However, if a feature appears to be rich in organics or might have large numbers of small objects, screening the dirt through 1/8 inch wire mesh (window screen) is required. When screening, stop occasionally while shaking the screen to see if small items such as straight pins have ‘floated’ to the top. Never use your trowel, a block of wood, or any other object to push dirt through the screen. Rather, use your fingers to gently break apart dirt clods. Once the dirt is out of the screen, look over the screen’s contexts systematically for anything you may have missed. At the Mann-Simons site, we need to be cognizant of the lawns maintained by Columbia Housing Authority and the general aesthetics of the area. Do not create a new back-dirt pile without first checking with a supervisor. We would rather have one large pile of dirt instead of a series of small dirt piles all over the site. Remember that we are guests at the site.

N.

FIELD BAG PROCEDURES

To ensure that all bags are in a standard form, the same bag labeling format must be used. Bag labels should include in the upper left hand corner the site number, site name, grid coordinates, unit number/provenience letter, and stratum or feature short title. The lower left hand corner includes the date (expressed as DAY MONTH YEAR) and the initials(s) of the excavator(s) (see example).

We use polyethylene, ‘zip-lock’ type bags in the field and lab. Before using the bags, fill the label out completely and punch a few small holes in the bags to reduce the level of condensation. Small holes can be punched with the tip of a pencil, a small nail, or even a pin. If the holes are too large, artifacts might fall out or cause the bag to rip.

An artifact control card is placed within each bag. The artifact control card is used to track the movement of artifacts throughout the digging, washing, and sorting process. The top part of the card is filled out in the field, placed in a small manila envelope, and included in each stratum/feature bag. It is extremely important that this card be filled out accurately and completely. As the artifacts from a particular provenience are washed and sorted, the card is maintained with them. After the sorting process into artifact classes, the card is filed as a permanent record.

O.

HANDLING ARTIFACTS IN THE FIELD

As you find them, put the artifacts in the bags you prepared before digging/screening. Keep all objects made, altered, or used by humans. This includes modern materials like plastic and Styrofoam. The only exception to this rule is

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when you are digging/screening a stratum, in which case we do not save brick, mortar, plaster, cinders, slag, charcoal, or coal. Save only a small representative sample of these and be sure to record their presence and relative frequency (expressed as a percentage) on the provenience form. This is because in different ways, each of the four primary strata at the site has been disturbed. However, we do save all these materials from features. The general rule is: when in doubt, save it!

At a minimum, each discrete provenience will have two bags, one for metal objects and one for all other materials.

Very small items like beads and straight pins, and fragile, easily crushed materials like decayed glass, leather, cloth, egg shell, tin cans, etc. must be placed in a protective container, such as a small bag or film canister, before placing in the bag. We have many different sizes of bags available at the site. If more than one bag is made for a stratum or feature, each bag must be marked with an indication of the number of total bags, such as “1 of 5”, “2 of 5” etc. (written in the lower, right-hand side of the white writing block on the bag) and each must contain the full bag label.

General points to remember:

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Do not fill bags too full as they may tear and excess weight may cause objects to be damaged. In general, bags should not be more than half full.

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Do not pack large, heavy objects together with smaller, more fragile objects.

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Use the correct sized bag or container for the artifact(s). Very tight fits may lead to damage when the object is inserted and removed.

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Avoid placing/leaving artifact bags in direct sunlight. Sunlight promotes condensation in the bag and other damage caused by UV radiation.

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Do not place bags near walkways, etc. where they will be stepped on or crushed.

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Never place a freshly excavated artifact at the edge of the unit. They become easily forgotten, lost in the grass, or stepped on by others.

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Remember that artifacts always look more robust than they actually are, particularly metals.

Corrosion and dirt can obscure cracks, giving a false sense of stability. In some cases, the dirt may be all that is holding the object together. This is particularly true of tin cans. Treat all artifacts as if they are FRAGILE!

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Do not wash or try to clean artifacts in the field.

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Do not wrap artifacts in paper towels or use them to brush the dirt off artifacts. Paper towels contain acids that can be harmful to artifacts.

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If you encounter organic materials other than bone or shell (e.g. leather, textiles, wood, etc.), let your supervisor know immediately. It is important to keep organic materials in the same condition as they are found. Wetting, drying, and other environmental changes can lead to irreversible structural damage.

P.

IDENTIFYING EXCAVATED MATERIALS IN THE FIELD

[Sections ‘P’ and ‘Q’ are extracted, with minor modification, from the Society for Historical Archaeology Conservation FAQ]

When an artifact is freshly excavated, its appearance, weight, color, shape and even size may all give clues about the materials it is composed of, as well as the type of artifact it is. Below are some indicators that may help to identify excavated materials. It is important to remember that every artifact is unique. As artifacts decay in the ground their appearance may be altered, and this change is different for every type of site or burial environment.

Metals The colors of metal corrosion products are usually the most helpful feature in identifying different metals. On aerated sites:    

Iron--turns orange, red and brown and is often lumpy and misshapen.

Copper alloys--will be shades of green with brown, red and/or purple.

Lead and other white metals--will turn white/gray, brown and/or pinkish, may be fissured.

Silver--is often gray or blackened, alloys may be green and may be mistaken for copper.

On poorly oxygenated or anaerobic sites:    

Iron--often red but may quickly oxidize to orange, may have a fissured, wood-grain appearance.

Copper alloys-black, purple-black, some green products, or yellow metal exposed.

Silver--blackened.

Lead and other white metal--may be black.

Other features also provide clues. Lead or alloys containing lead are typically heavier than their appearance warrants, due to the higher density of lead compared to other metals. Iron is magnetic, so a simple magnet test may indicate the presence of iron or ferrous alloys.

Glass On aerated sites glass often appears iridescent and may contain layers of adhered insoluble salts mixed with soil and burial debris. It may be difficult to determine the original color of the glass, but the form, size and thickness of the glass may determine whether it is bottle, table or window glass. On anaerobic sites, glass may often appear unaltered, but may be worn slightly and covered in a thin layer of oxidation. Upon drying, damp glass may lose its saturated appearance and become more iridescent and opaque.

Ceramics It is usually easy to identify an artifact as a ceramic of some kind, but it may not be easy to identify the specific type without some cleaning or analysis. Ceramic features can sometimes be masked by soil, soluble and insoluble salt encrustations and staining from minerals in the soil or from nearby metals. It may be necessary to wait until cleaning has been undertaken before trying to identify ceramic types.

Bone, Ivory, Antler and other Bony Materials Bony materials tend to be creamy white materials, however they can be intentionally dyed a range of colors, from green to red to black, and in the burial environment may become stained by proximity to metals. Bone usually retains a harder surface than other organic materials. It can often be identified by the caniculi on the surface; these

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usually manifest themselves as small block dots where soil has filled small blood vessels or caniculi. If bone has been burnt a mottled effect may be apparent, with colors ranging from white to black evident. Antler has a characteristic rough grooved pattern and a core of spongy tissue. Artifacts made from antler often incorporate areas of the patterning. Ivory is difficult to distinguish from bone in field situations.

Organics (other than bony materials) Organic objects (such as wood, leather and textiles) survive primarily in waterlogged anaerobic conditions or in association with metals. They often appear blackened, soft and very spongy. Most of these materials will be recognizable, but details about the objects may be masked. However, information will be lost if cleaning is started before careful examination, preferably with a microscope. Wood can usually be identified by the grain visible on tangential or radial sections, and the concentric growth rings on cross-sections. Cracks will tend to form along the long axis, and radially out from the middle of round-wood. Highly degraded and rotted wood will crack across the grain, sometimes forming right angle intersections that break up into small rectangular or square chunks. Leather has a fibrous appearance and may show signs of delamination at the edges. Highly degraded leather in proximity to iron may look like powdery iron corrosion.

Textiles can often be identified by the weave pattern on the surface.

Q.

KEEPING ARTIFACTS WET OR DRY

When deciding whether to dry out a freshly excavated artifact or keep it damp, the answer is based on the real question, which is: What will do it the most harm: staying wet, or drying out? This can usually be decided based on the material class of the object, and the burial environment from which it came. The following table is offered as a general guide.

Material Class

In General

Ceramic (porous)

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Dry

Damp (subsurface soils)

Here you have to be worried about the If it's dry, leave it that effects of drying, way. versus the effects of moisture-driven corrosion or decay.

If it's dry, it's probably ok. But beware of wetcleaning porous ceramics from salty soils, as the water may dissolve, then reactivate crystallization that may degrade the ceramic.

Waterlogged: Fresh Water Here you have to be worried about the effects of drying, versus the effects of moisture-driven corrosion or decay.

Low-fired ceramics are weaker when damp than when dry.

Ceramics can be slowdried, but watch Similar to damp carefully for salt conditions crystallization which will damage ceramic body and surface treatments.

Waterlogged: Marine Here you have to be worried about the effects of dissolved salts that can physically damage porous materials, or drive corrosion processes. Never allow marine concretions to dry out, they are much easier to remove when wet.

Keep wet. Do not dry out until soluble salts have been removed by washing in purified water. Washing endpoint should be determined by using some dissolved solid measuring system. Slow-dry under controlled conditions.

Ceramic (vitreous)

They can stay dry.

As for vitreous As for vitreous ceramics ceramics See the appropriate See the appropriate ceramics class, either ceramics class, either porous or vitreous. porous or vitreous.

Stone Note that some stones Note that some stones are water-soluble. are water-soluble.

Determine the degree of decay and cellulary loss. It may be possible Keep it wet.

Leave it dry, and move to consolidate fragile Waterlogged "hard to a controlled materials in situ with tissues" must be humidity environment water based resins to treated very carefully Bone/ tooth/ (ca. 55%RH). Very aid in excavation. It to prevent cracking horn/ Ivory fragile materials may may be possible to and loss during be consolidated in situ slow-dry very carefully, drying. If possible, to aid in excavation. and move to a keep in a dark cool controlled humidity place to retard decay. environment (ca. 55% RH) Compromise between Compromise between the needs of the most the needs of the most Keep it wet. Drying sensitive material sensitive material out a composite object robust organic robust organic can be very tricky, as materials can tolerate materials can tolerate the treatments for Composite low RH (to about low RH (to about (metal/organic) organics and metals 30% RH) needed to 30% RH) needed to involve materials that reduce metal corrosion reduce metal corrosion may cause damage to rates, but the rate of rates, but the rate of both components.

RH decrease should RH decrease should not be abrupt. not be abrupt.

Glass

As for vitreous ceramics See the appropriate ceramics class, either porous or vitreous.

Note that some stones are water-soluble.

Most vitreous ceramic bodies (porcelain, stoneware) are not subject to crystalization Similar to damp pressures, but be conditions cautious with glazed or overpainted surfaces.

Slow-dry under controlled conditions.

As with damp materials, be cautious of overpaints or glazes that might be affected by salt crystallization.

Desalination is always a safe step.

Slow-dry under controlled conditions.

As for vitreous ceramics See the appropriate ceramics class, either porous or vitreous. Note that some stones are water-soluble.

Keep it wet. Waterlogged "hard tissues" from marine sites must be desalinated and treated very carefully to prevent shrinkage and loss during drying. If possible, keep in a dark cool place to retard decay.

Keep it wet. Drying out a composite object can be very tricky, as the treatments for organics and metals involve materials that may cause damage to both components.

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R.

PUBLIC ARCHAEOLOGY

Because we are excavating at an urban site visible to the public, sometimes we will have visitors. People will be curious about what you are doing, as many have probably never seen archaeology being done before. Keep in mind that whenever we are on the site, we represent the Columbia Archaeology Program. Community support and interest is vital to the success of the program.

It is very important that you answer visitors’ questions courteously, regardless if the questions seem somewhat simplistic. Positive visitor experiences are among the most effective forums we have for telling people about our research. Answer questions as best you can—remember, you know more about what is going on than they do. Try to relate the archaeology to the area being excavated and try to place the artifacts within a larger context (stress the project goals).

If a visitor asks to see artifacts (this is rare, but it happens), show a few examples, but discourage handling. Artifacts are dirty, possibly sharp, fragile, and easily lost if dropped. Consider yourself a steward: take care of the artifacts, but remember that they belong to everyone. Archaeology is more than just digging up stuff. Remind visitors of the work done in the lab (a good rule of thumb is 3-4 months in the lab for every month in the field). Archaeology has value for more than just the stuff we find—it provides valuable information about everyday life for those who once lived here.

Be aware that ‘relic hunters’, ‘bottle hunters’, and the like may (likely will) approach you and ask questions. Don’t snub them, but try not to give information that helps or encourages them (e.g., don’t tell them you found a silver coin at the site or an intact, rare bottle). Let people know that we rarely, IF EVER, find these items and that they are not what we are looking for through archaeology.

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