Archaeological Analysis

When the last excavated trench is backfilled with dirt and when survey is completed for another season, one is left with only the records, drawings, photographs, and cultural material to make sense of what everything means. The processing and interpretation of those material remains, in conjunction with the records, is the essential final step in completing the picture of past human activities occurring in an area over time. Artifacts, ecofacts, and features say little themselves, but researchers can make meaningful inferences about these when they are studied closely and in detail. Analysis is the examination, description, classification, and identification of that material, as well as consideration of its broader meaning. As will be seen in this section, data analysis is a vital part of fieldwork at Isthmia and a necessary preparatory step to making interpretations about past human activities.

Processing

(Figure 9.1) Remains of the pottery dumpEvery season, archaeological projects recover great quantities of artifacts, ecofacts, features, and other cultural and environmental matter that must be processed and managed in an efficient and systematic manner (Figure 9.1). In a multi-year excavation project such as the one at Isthmia, hundreds of thousands of objects and other cultural material fill the storage sheds and museum. Processing is the management of that archaeological material, beginning with decisions about how much to sample and ending with cleaning, sorting (preliminary analysis), inventory, and storage. It is the means by which researchers cope with the significant quantities of artifacts recovered annually and thereby stands as a preliminary step leading up to analysis.

Processing decisions begin with the research design and the goals tailored for each project. As we have seen in our discussion of excavation and survey, most projects employ sampling strategies that seriously reduce the amount of matter brought back for analysis. In the excavations at Isthmia, this involves sifting only a percentage of the dirt from each stratum and discarding the rest; sieving soil through wire mesh also reduces the number of total artifacts since smaller objects are not preserved. Systematic survey in the Eastern Korinthia necessarily samples since walkers are often arrayed 10 or more meters apart, a total visual coverage rarely more than 20%. Moreover, using EKAS' ChronoType system, only representative objects are flagged, avoiding redundancy and diminishing the work required of the Processing Team. Unlike the Isthmia excavations, the EKAS project removes few artifacts from the field and this saves enormous amounts of time in processing back at the Excavation House. Thus, OSU's processing and analysis techniques are tailored to the specific projects: the EKAS project employs a non-collection strategy and so all processing takes place in the field, while the excavations at Isthmia process material at the site as well as at the Excavation House.

Cleaning:

(Figure 9.2) Worker cleaning ceramic pieces.Before any analysis takes place, artifacts must be cleaned either on-site or back at the project's headquarters (Figure 9.2). Soils and sediments build up on objects through time to form thin layers of "encrustation" which cloud the exterior surface of the artifacts. Even when the objects are not taken back to a laboratory, a washing is often necessary to elucidate the exterior surface, which is important in analyzing and dating the artifact. The washing is done simply with water and brush, or, if the encrustation is too hard and cemented, the artifacts are soaked in a weak mixture of hydrochloric acid and water. This acid bath will certainly remove most of the crust (and the artifact itself, if soaked too long or not rinsed thoroughly). After the wash, artifacts are allowed to dry overnight (or longer if necessary). While they are being washed, and at every step in the recording process, great care must be taken that the artifacts do not get mixed up and that they retain their association with their archaeological context is maintained.

Cleaning artifacts is an important but time-consuming task in every archaeological project, and it is essential that a team keep up, lest an overwhelming amount of processing be left for the end of the season. At Isthmia, assigned crew members wash hundreds of new objects at the end of every day. The other real concern in this process is that the artifacts will lose their provenience, through strong winds or careless artifact handling. Attempting to reassign artifacts to their context is risky business; wrongly assigning the artifact contaminates the collection of another provenience.

Sorting:

(Figure 9.3) Sorting of the material into broadly distinct classes.Artifact cleaning is usually followed with a preliminary sorting of the material into broadly distinct classes: ceramic, stone, bone, coins, architecture, and other (Figure 9.3). When the material is dry, the artifact classes from the same Lot are bagged together, all the bags from the same context being stored in a larger box. Information about the archaeological context and excavation date is written on the outside of the bags and boxes, as well as on tags which are placed inside the bags; this reduces the risk that that the context will be lost during the processing or storage.

Inventory:

Some artifacts may be selected for inventory, which involves "naming" the object. Artifacts are assigned unique numbers by which they are referred in subsequent analysis and discussion. In some areas (e.g., North America), where artifacts are comparatively fewer, it may be feasible to inventory all or most objects recovered in survey or excavation. However, in Mediterranean areas, where artifacts are overwhelming in numbers, researchers select objects considered important and unique, or well preserved and representative of similar objects. Inventory, then, is a way of processing and managing all that material. Although the Eastern Korinthia Survey project rarely inventories objects (as we have seen, artifacts are rarely removed from the field), the Excavation House and museum at Isthmia are filled with inventoried objects from years of excavation. In the series of reports of the excavations at Isthmia, the inventory number has given researchers a convenient way to refer to artifacts by name.

Isthmia has a well-developed system for managing its finds. The inventory number is usually written directly onto the surface of the artifact, or when that is not possible or desirable, onto a tag attached to the object. The number contains three parts:

        TYPE OF OBJECT -- YEAR -- RUNNING NUMBER

The artifact is assigned to a specific "object type," a class of material ranging from pottery to coins to sculpture. At Isthmia, the following abbreviations exist:

        IA (Architecture)
        IC (Coins)
        IM (Miscellaneous: small finds, jewelry, etc.)
        IPB (Byzantine Pottery)
        IPG (Greek Pottery)
        IPL (Lamps)
        IPR (Roman Pottery)
        IS (Sculpture)
        IS (Inscriptions)

Artifacts are also designated by the last two digits of the year the object was discovered. Because there are usually multiple artifacts of the same type found in each field season, the artifact is also assigned an individual number that identifies the object within its class and year. The assigning of this specific "running number" is based on the order in which the object is inventoried. The following artifacts, for example, line the shelves of the Isthmia excavation house:

IPL 78-23       The 23rd lamp inventoried in 1978.
IPB 68-124     The 124th Byzantine sherd inventoried from 1968.
IS 93-1           The first piece of sculpture from 1993.
IC 90-4           The 4th coin from 1990.

An inventory card is filled out for each labeled object that includes additional information about the object. The archaeological context is noted along with references to appropriate field notebooks that discuss the original recovery in more detail. The condition, decoration, and dimensions of the object are described in great detail. A photograph of the object is glued to the card and the physical location of the object (e.g., in the excavation shed or the Isthmia archaeological museum) is also noted. The inventory cards are filed by year and stored in a cabinet at the Excavation House. This system allows researchers an effective way of locating specific objects among the thousands of artifacts which have been recovered through excavation and survey.

Artifacts

A basic concept that underlines archaeological analysis are the attributes of artifacts. Attributes are those physical characteristics of artifacts that make it possible to say anything meaningful about the artifacts themselves. Artifacts are sorted by similarities and differences in these attributes. Artifacts may be analyzed in terms of 1) surface attributes such as decoration and color, 2) attributes of form such as dimension, shape, and size, or 3) technological attributes such as the raw material. Each kind of artifact characteristic provides different information about past cultures. For example, the style of a stone spear point (e.g., where hafting or notching occurs on the point) may suggest a particular cultural tradition and the date of manufacture; the large size and shape may suggest the use of the spear point for big-game hunting; and the use of material such as obsidian might indicate trade connections with a particular place. It is the task of the archaeologist to decide what kind of information to analyze and data to collect.

(Figure 9.4) Lithics.The similarities in artifact attributes may be used to construct an artifact typology, the hierarchical arrangement and ordering of classes (types) of artifacts (Figure 9.4). For every kind of material (e.g., ceramic, stone), archaeologists can assign artifacts to types based on similar physical attributes such as shape, size, and decoration. Because the style of artifacts changes slowly over time, archaeologists can order the artifacts into sequences in which one artifact is related stylistically to another. Moreover, since these changes often represent developments in style over time, archeologists can create relative chronologies in which a stylistic development in an artifact type signifies a later point in time. When one type of pottery is discovered with diagnostic artifacts such as coins or inscriptions, or is related to a radiocarbon dated context, archaeologists can create absolute chronologies. Once these are established for a period and area, the discovery of certain artifact types at other sites can provide reliable dates for those sites.

Analysis of artifacts at Isthmia occurs at two levels. On the one hand, general information is recorded about the artifacts in each Lot. Artifacts are sorted, counted, and weighed by each chronological period (Prehistoric, Greek, Early Roman, Late Roman, Early Byzantine, Late Byzantine, Modern, and Undatable), material class (fine and coarse pottery, lamps, tiles, metal, glass, stone), and ChronoType (an object that is physically and chronologically unique). On the other hand, more specific descriptions and measurements are made for inventoried objects. This twofold system allows archaeologists to make inferences and comparisons about entire artifact groups, as well as specific artifacts, within each Lot.

Ceramics:

(Figure 9.5) Greek ceramics.Ceramics are the most common type of artifact found in Mediterranean archaeology since clay pots were usually the primary (and, oftentimes, only) means of storage, cooking, and transport during ancient times (Figure 9.5). Because well-baked clay breaks down slowly through time and pottery has little real reuse value (unlike metal and marble objects which were often used for construction or warfare), sherds survive abundantly in the archeological record. Moreover, ceramics are excellent indicators of cultural activity in the Mediterranean area. Since pottery is so abundant and excavation has traditionally dominated archaeology, tightly dated chronologies exist for many periods of ancient history and a potsherd may indicate a very restricted period of production. The analysis of ceramics then is a very important part of archaeological fieldwork.

Analysis of ceramics at Isthmia begins with an initial sorting into broadly periodic (e.g., Roman), functional (e.g., fine ware), typological (e.g., pottery), morphological (e.g., rim sherd) classes for each lot. As discussed, all sherds are also grouped into ChronoTypes, a categorization that is both physically and chronologically distinct. For example, the ARS ChronoType represents African Red Slip pottery, a Late Roman fine ware produced from the third to seventh centuries AD. Potsherds are counted and weighed for each class and forms filled out recording these values. This is the end of the road for some of the potsherds, and they are redeposited in dusty storage boxes until a later day when some analyst has specific questions about the contents of the Lot. Pottery of this kind is called ³context pottery,² to separate it from the inventoried pottery.

Inventoried artifacts, however, are analyzed much more closely. The dimensions (height, length, thickness) of the sherd are measured in meters with metal tapes or calipers. These values give some indication of the form and function of the vessel. Generally speaking, thicker vessels were put to more utilitarian purposes than thin-walled vessels. Pithoi, for example, are thick, gigantic storage vessels that were most certainly used for storage and were often produced locally.

The fabric is the physical composition of the pottery and is described in terms of the clay, the color, and the temper. The clay may be fine, medium, or coarse, indicative of the source of the clay as well as vessel function (coarser jars generally put to heavier use). Color is measured using a Munsell color chart for the exterior, interior, and core surfaces. The lightness / darkness of color illuminates the atmosphere of the firing process, ceramic technology, and the source of clays. Temper is the filler material added to clay to prevent the pot from breaking during the firing process and to give it special characteristics. Potters used a great variety of temper for this purpose: grit (crushed crystalline rock), grog (crushed pottery), shell, and even some types of reeds and grasses. The temper type is noted, and the size (average and range) for each sherd is estimated. Generally, the analysis and determination of the clay, color, and temper indicate the function of the vessel and the sources of physical materials. If the vessel is locally produced, scientific analysis of the fabric may enable one to determine the exact clay bed from which the clay was extracted.

The decoration of ceramics is described and measured whenever possible. Decoration includes surface treatments such as painting, slips, glazes, wheel marks, incisions, and excisions. The decoration of the exterior surface indicates cultural values and may be used to date the pot stylistically. Examples of comparatively similar decorations and styles may be found from other excavated contexts, providing a date for the ceramic ware.

(Figure 9.6) RIm sherd.Rim sherds are analyzed in greater detail than normal body sherds since they generally provide better indication of the form and shape of the vessel (Figure 9.6). Rim stance is the position of the rim when oriented correctly. Rims flare outward, slope inward, or are simple and vertical. Moreover, the lip treatment (square, rounded, pointed) and the presence of rim thickening are also associated with certain styles and ChronoTypes. When rim sherds are oriented correctly and compared to a "diameter chart," it is possible to estimate the orifice diameter, the size of the vessel opening. Using all this information, archaeologists ascertain the vessel form, determining the shape and size of the whole pot from a single sherd or two.

Lithics:

Lithic artifacts are rarely found in excavations at Isthmia but are commonly discovered in the Eastern Korinthia Survey. Stone tools were more typical in prehistoric times but were sometimes used well into the classical period and even later. As in the Americas, prehistoric Europe developed standard techniques for knapping material into knives, blades, and projectile points. Local outcroppings of chert and flint were sought to craft weapons and tools. By holding "cores" of raw flint at certain angles and striking the flint block with another "hammer" stone, smaller "flakes" which were chipped away could be manipulated into tools. Today, these flintknapping processes are reflected in the cores, flakes, and tools left behind on the landscape. Indeed, the permanency of stone has meant that lithics are common finds in many survey projects.

The analysis of lithic artifacts is in some ways similar to that of pottery. Artifacts are sorted into various classes that reflect the process of manufacture or the function of the artifact; counts and weight are taken for these classes. At the basic level are the debitage remains: stone cores, large blocky flakes, thinner flakes, exhausted cores (where the cores have been worked so much that they are no longer useable), and thinning flakes (from the final steps of tool making). Oftentimes, flakes were utilized as tools or made into tools, apparent in their dulled or worked edges. All lithics are examined for this kind of utilization with microscope or magnifying glass.

Tools are objects that have been clearly modified by retouching with hammer stones, bones, or antler tine. This is apparent in the marks on the surface edges of the stone where small "trimming flakes" were removed to sharpen the edge. Tools worked on only one face of the stone are described as unifacial, while retouch on both sides is called bifacial. Stone tools exist in a variety of forms (knives, blades, bladelets, projectile points, and drills) and are analyzed in terms of dimension, styles, color, and material.

The dimensions of a tool may indicate technological capacities, modes of manufacture, or function. For example, spear points are associated with human activities such as hunting, warfare, and ritual; the size of a point may illuminate which activity is most likely.

(Figure 9.7) A piece of obsidian rock.Like pottery, the styles of tools change over time and where typologies of stone tools exist, it may be possible to use tools as a means of dating. This is especially true of projectile points, since the shape, curvature, and form of base are associated with particular traditions. When these are found on the landscape or in excavated contexts, they aid in providing dates for the use of the area.

Lithic material may indicate trade, long-distance connections, or the utilization of the local environment (Figure 9.7). For example, obsidian bladelets found during survey indicate trade connections with the island of Melos to the south of Greece, while some flints may be traced to local outcroppings. Moreover, distinctive forms and shapes are associated with certain activities. Knives and blades were certainly used for cutting; scrapers used for removing meat from hides; points for war and hunting. Finally, the microscopic examination of the residues left on the edges of stone tools will reveal the more specific activities to which the tool was applied.

Microanalysis: Analyzing Ecofacts

Artifacts are only one class of material that provides information about past human cultures. In order to gain a fuller understanding, archaeologists must also examine ecofacts, the environmental and organic remains that reveal past ecosystems, climate, and ancient diet. Floral (plant) and faunal (animal) remains are a necessary and significant part of archaeological analysis.

Floral Remains: Ancient plant residues are important indicators of changing plant environment, past climate, and plant cultivation, all of which reflect on past human behaviors. For these reasons, analysis of plant remains has become a significant aspect of excavation and survey. The study of pollen (called palynology) has become important especially for illuminating changing patterns of plant population in an area. Because plants are everywhere emitting pollen grains and because the outer shell (exine) is virtually indestructible under certain conditions (in moist, low oxygen atmospheres: marshes and peat bogs), the analysis of pollen is a reliable means of reconstructing past environments.

In archaeological excavation and regional survey, pollen is collected by extracting sediments through a technique known as coring. A hollow pipe, several meters long, is drilled deep into the bottom of a marsh or peat bog, and layers of sediments are extracted which contain pollen grains. When taken back to a lab, these sediment cores undergo a physical and geochemical analysis. Small samples are examined at set intervals and processed with an acid solution so that only the pollen grains remain. Because pollen grains are unique in shape, size, and physical appearance, specific plant genus (and in some cases, species) can be identified under the microscope. The pollen analyst then faces the daunting task of manually counting the total number of pollen grains for each genus. This information can then be used to create pollen sequences, which list percentages of pollen by type, and pollen diagrams, which show the changes of these percentages through time. All of this is used to illuminate local environment and vegetation changes, which can be tied to absolute dates through radiocarbon dating. It is then possible to make inferences about the responses of vegetation to climatic changes and the pressure of humans on the environment.

Plant data is also collected during excavation in a process known as flotation, or water sieving. Soil is dumped into a vat of water and materials are separated by density. Denser, heavy material such as minerals and artifacts, sinks to the bottom of the vat, while less dense organic remains float on the surface. After this floating material is skimmed off the water surface and allowed to dry, researchers manually sort the plant remains into a variety of categories: seeds and seed pods, wood fragments, charcoal, roots, shell, and miscellaneous material. This painstaking and tedious process requires a great deal of patience, as well as a certain level of skill in identifying the various kinds of material. However, the payoff is high in the information it provides about past environment. Like pollen, it may be possible with a microscope to identify specific plant species and genuses in the seeds, roots, wood, and charcoal remains; this information can be used to make inferences about plant cultivation, ecosystem, and diet.

Faunal Remains: Animal remains are important indicators of ancient diet, husbandry, and climate. In the flotation process described above, the heavier, denser material sinks to the bottom of the vat and this is "water sieved" through fine mesh. In many archaeological contexts, the tiny remains which are left when the silt and earth is washed away consist largely of animal (faunal) remains. Like plants, these can be sorted out by species and used to infer about ancient diet and local environment.

Changing quantities of microfaunal (small animal) remains, such as rodents, bats, birds, mollusks, and insects, may indicate climatic changes, since these animals are sensitive to shifting environmental patterns. Macrofaunal (large animal) remains indicate diet and husbandry in past cultures. Archaeologists can estimate the minimum number of animals of the same species present at a site by determining the number of unrepeated elements for each species. Some species can be linked with particular activities, like sheep and goats with pastoralism, deer and wild boar with hunting, and oxen with plowing. Moreover, faunal analysts can, by determination of the sex or age of the animal, make fuller statements about the nature of the use of the animal or the site. For example, a significantly greater number of younger deer may indicate a preference for skins rather than meat. Or the presence of certain animals may suggest the use of sites at particular seasons.

Finally, bones are examined under microscope and magnifying glass for evidence of modification. Bone which has been burned in a fire often turns a variety of colors (red to blue to black), and it is also possible to ascertain activities such as cooking, boiling, disarticulation, and butchering through the marks left on bone.

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