The analysis of pottery and ceramics is an important aspect of both prehistoric and historical archaeology. The methods and techniques used in studying ceramics are diverse and many archaeologists specialise within this field.
Ceramics are considered good to excellent temporal markers in many diverse regions of the globe and useful for dating archaeological components and sites. Ceramics have been used to describe and document many aspects of culture which include settlement patterns, linguistics, trade, socio-political organization, and information / exchange networks.
The terms and definitions presented below are provided as a general reference useful in describing ceramic sherds and assemblages. Highlighted terms lead to more detailed definitions and /or illustrations of ceramic attributes.
Technological attributes are related to the manufacture of ceramic vessels. The selection of raw clays, preparation of paste, and firing all involve a complex series of decisions in order to successfully manufacture a useable vessel.
Clays are produced through two basic geological processes, either by: 1) the weathering of bedrock; or 2) the deposition of fine grained sediments in water. Clay particles measure less than 0.005 millimeters in diameter.
The clay matrix refers to both the clay and constituent materials. Raw clays often contain mineral and/or organic inclusions which must be removed or cleaned during vessel construction.
Ceramic paste refers to the prepared mass of clay that is transformed into a material used in the construction of pottery. Paste can be described as fine, medium, or coarse grained, but also in terms of porosity, quantity of temper, or organic material.
Holes drilled through the vessel wall to repair cracks. Holes would be drilled on either side of the crack and then laced with cordage. Examination of most punctations on Windsor (New England) pottery shows evidence of bi-conical drill marks.
Material added to a clay in the formation of vessels or other objects. Temper is added to clay in order to reduce rapid shrinkage and /or expansion during the firing process. Temper allows for a more even distribution of heat energy through the ceramic paste during firing and/or use of the vessel. Uneven heat distribution can result in cracking and failure during the manufacturing process.
A variety of materials can be used as ceramic temper such as crushed shell, sand, crushed stone, organic fibers, and crushed pottery.
Morphological attributes are related to the form and shape of a vessel.
The bottom of a vessel is referred to as the base. Portions of a base found at archaeological sites are known as basal sherds. Vessel bases occur in three basic forms: 1) conoidal (pointed), globular (rounded) or flat. Basal sherds are usually the thickest sherds from a vessel.
Body sherds typically lack morphological attributes and occur as either flat or slightly curved. The curvature of body sherds can serve as an indication of the general vessel shape.
Castellations provide relief to the vessel rim or opening. This practice often results in a series of ‘points’ around the rim and produces a squared, rather than round vessel opening. The manufacture of castellations on pottery is relatively uncommon.
Vessel collars are located below the rim and above the neck. When present, collars usually consist of thickened areas that provide extra relief to the vessel wall profile. Occaisionally, collars are used as decoration with the addition of nodes or lobes. Frilled collars have been noted on late Woodland pottery of the eastern United States.
The lip is the very edge tip of the vessel opening – all vessels by definition have a lip. Lip profiles (cross sections) can be angular, flattened (parallel to the base), rounded, squared (perpendicular to the axis of the rim wall), thickened (‘bevelled’) or thinned (‘peaked’).
Rims typically refer to the vessel opening. Rims are usually described in terms of their profile as either straight, inverted, or everted.
When present, necks are characterized by the degree of inflection or constriction in the overall vessel profile. Necks are located below the rim and above the shoulder. When present, neck sherds are relatively thin compared with sherd thickness on other parts of the vessel.
Vessel shoulders typically include the widest portion of the vessel.
The volume of a pottery vessel often is a product of the vessel function. Storage, cooking, and processing activities often require different kinds of containers. Sizes can range from very large vessels for storage to miniature containers for medicines or other precious materials.
surface treatment and stylistic attributes
The study of pottery decoration is one of the most widely reported aspects of ceramic analysis. Unlike stone or other materials found at prehistoric archaeological sites, pottery is easily formed and allows for a wide range of creative expressions. A variety of tools are used in the production of ceramics and execution of decoration.
In many regions of the world, archaeologists have noted that pottery decorations became standardized at different times during prehistory. In this respect, pottery decoration may have served as social markers or ethnic markers. At the same time, variability has been observed within types and traditions which can be used to describe social and political organization.
The terms presented below describe the basic methods and techniques used in the construction of pottery designs.
Brushing is characterized by a series of overlapping and uneven lines which often cover the entire exterior and/or interior surfaces. This form of surface treatment results from the use of a brush constructed from fiber, quills, stone, or shell. The brushing technique may have been used to create a surface bond between the coils used in pottery manufacture.
A method used to smooth a vessel surface. In burnishing a vessel, a smooth object like a stone is rubbed over a vessel surface. The result is a polished surface. This method also strengthens the surface bond of clay particles.
Cord marking is fairly common in the early ceramic horizons identified in most parts of the world. A cord marked surface is often highly textured and marked by overlapping rows of cord impressions. Under a low power microscope the individual cords and fibers used in cord manufacture can be observed. The cordage was usually woven from plant or animal materials and either wrapped around a paddle or a stick. Examinations of cord impressed ceramics can provide information regarding the manufacture of textiles, which are rarely found at prehistoric sites. The patterns of cord impressions are referred to as either ‘s’ twist or ‘z’ twist. Cord marking is found on decorated and undecorated pots. On decorated pots, the cord markings are often arranged into horizontal or vertical bands or zones. On undecorated vessels, cord marking may have been used to create a surface bond between clay coils as part of the manufacture process.
Like cord marking, fabric marked ceramics can provide important information regarding prehistoric textile technology. Unlike cord marking, this method uses sections of woven fabrics in the surface treatment rather than a single cord. Fabric marked ceramics are also referred to as net-marked.
Glazes consist of glassy or metallic chemicals which are painted onto a vessel surface. When fired, the chemicals in the glaze vitrify and create a glassy surface which strengthens the vessel body.
This method of decoration utilizes a sharp instrument such as a bone, shell, or stone tool. Incised decorations usually include rows or patterns of straight lines which are arranged into zones. Incised decoration can be determined microscopically by the characteristic ‘v-shaped’ valleys which result from using a sharp instrument.
Linear dentate stamping utilizes a tool resembling a comb, with a row of “teeth” or tines. Linear bands of stamps are usually arranged in bands or parallel rows around the circumference of the vessel. Linear dentate tools may be made from carved wood, chipped stone, bone, or antler.
Notching is usually found on vessel rims and/or collars. This form of decoration consists of a series of single incised or impressed lines.
Mineral and vegetal pigments can be used to create a variety of paints. In some parts of the world, painted decorations replaced incised or stamped decorations.
Rocker dentate stamping utilizes a toothed instrument similar to linear dentate. These two methods of decoration differ in terms of the orientation of the tool on the vessel surface. In rocker dentate designs, the tool is impressed and then pivoted at one end. The result is a ‘saw-toothed’ design.
single point dentate
Single point dentate decorations usually consist of a tool which is repeatedly pressed into the clay surface. Single point dentate tools can include finger-nails, reeds, and/or sticks or carved bone tools. Often, the single point dentate impression is repeated to create uneven bands or rows.
Shell edges are often used in pottery decoration. Shell stamping can be applied using linear or rocker dentate techniques.
Slip consists of extremely fine grained clay particles which are sorted out from the clay matrix by soaking in water. Slip is often applied to exterior and interior vessel surfaces as a method for strengthening the bonds between coils and also to create a smooth surface.
The smoothing of vessel surfaces can be achieved by wiping, burnishing or the application of slip.
“stamp and drag”
A method of shell impressed decoration in which the shell edge is impressed and then dragged. This method often obliterates the wavy line characteristic of shell stamping.