Pottery often had multiple functions in the past and played an important role in human life.
Ceramics in the form of abundant sherds and occasional vessels are one of the more common archaeological materials to survive over the last 8,000 years or so.
Ceramic analysis then is a key part of many archaeological investigations, and the subject of this chapter.
Ceramic is a remarkable material.
Firing soft clay to create a hard ceramic was an important discovery permitting the invention of containers.
The earliest known use of fired clay is for small human and animal figurines dating from about 25,000 years ago in the Upper Paleolithic in Europe.
The first ceramic containers, actual pottery, appeared around 12,000 years ago in Japan and China.
There are many different kinds of pottery.
The kinds of clay used, the firing temperature, and other factors are influential.
Broken pieces of pottery (known as sherds) are largely indestructible and found at many archaeological sites.
Pottery is a useful material for archaeologists because it is made in a regular way according to cultural patterns.
Patterns of production help archaeologists to understand the technology, activities, and interaction of different groups of people.
Changes in pottery size, shape, color, and design over time also provide important chronological indicators.
Making Pottery
Collecting Raw Materials
The primary material used to make ceramics is clay.
The properties found in clay are essential for the production of pottery.
Pottery-making peoples usually collect clays from nearby natural sources, usually within a few kilometers of their residence.
Clay is any very fine-grained sediment, deposited in water and usually found in former lake or stream deposits.
Clay in the ground is usually moist and can be dug out of its source.
Preparing the Paste
Natural deposits of clay are rarely suitable for making ceramics.
A mix of clay and other materials called a paste is normally used to make pottery.
Temper is a non-plastic substance intentionally added to clay in order to reduce breakage caused by shrinkage and firing.
Prehistoric ceramics are typically about 70-80% clay and 20-30% temper.
The temper allows a more even distribution of heat during the firing process.
A variety of materials can and have been used as temper including sand, shell, volcanic ash, pulverized sherds (known as grog), bone, or rock, and even organic materials such as grass and other fibers.
Shaping the Vessel
There are three major techniques for forming pottery: using the hands, a mold, or a wheel.
The most common methods in the past were coiling by hand or throwing on a wheel.
Each technique leaves distinctive marks that can be identified.
Hand-made ceramics were commonly made in one of three ways, using either a coil, paddle-and-anvil, or slab technique.
In the coil method, long ropes of clay are rolled out and used to build up the walls of the vessel.
The paddle-and-anvil method involves the use of tools to shape a lump of paste into a vessel.
Another hand technique for making pottery involves rolling a slab of clay into a cylinder or fitting slabs of clay together to make a cube.
Molded ceramics are produced by pressing clay into prepared molds, carved in stone, wood, or made from ceramic.
In some cases, pottery vessels are made from two or more castings that must be joined together before firing.
Molded ceramics can also be made by pouring liquid clay into a mold.
The mold technique results in virtually identical products and allows them to be made quickly.
Wheel-thrown ceramics appear relatively late in time, around 3000 B.C. in Southwest Asia.
The method permits faster, more efficient production.
A lump of paste on a spinning potter's wheel can be turned into a ceramic vessel in a matter of minutes compared.
Decoration
There are many different ways to decorate the surface of ceramic vessels.
Most forms of decoration are applied to the soft clay of the vessel before firing.
Some techniques served to enhance the use of vessel.
Decoration also functioned to signal individual or group identity.
In some cultures, decorations were used to tell stories and record events, myths, and legends.
A common technique in many areas involved some form of impression or incision in the soft clay of the unfired pot.
Impressions were made with many different tools.
Cord-marked pottery is one of the more common types of decoration in the past and is found on every continent.
Incising involves cutting designs into the soft clay of the unfired vessel.
Lines could be carved into the clay with a sharp stick, bone or flint using a stab and drag technique.
Designs were also stamped or rocked into soft clay.
Another form of decoration involved adding clay to the outside of the vessel, a technique known as appliqué.
Slips and glazes involve coating the surface of the unfired vessel with a liquid clay or another mixture that leaves a thin layer on the pot.
Slips and glazes can be applied by dipping, brushing, or wiping.
Slips usually are added to change the color of the surface of the pot and perhaps to reduce permeability.
Glazes are mixtures of metallic chemicals or glass, brushed or washed onto the surface of a pot to produce a distinctive finish.
Firing a glaze produces a hard and shiny surface distinct from the original clay material.
The earliest use of glaze on pottery is found in China ca. 1500 B.C.
A resist is a technique involving the use of material to prevent a slip or glaze from covering a portion of a vessel.
A great range of colors and designs were painted on pottery in the past.
Firing
After the pot is thrown and decorated, it is allowed to dry for sometime to remove water and stiffen the shape before firing.
Temperatures required for hardening clay are around 800°C and higher.
Firing can be done in an open fire or a kiln.
A kiln is a specialized oven or furnace for firing pottery.
A wide variety of kilns have been used in the past.
Temperatures are more controlled and higher in a kiln than in an open fire.
One important distinction for kilns is open or closed.
Oxygen is continuously available in open kilns.
Open kilns reach temperatures around 900°C.
Closed kilns can reach temperatures up to 1000 °C or more.
Vitrification fuses the clays in the pottery and makes it waterproof.
Oxidizing atmospheres produce pottery with dark, black cores, while reducing atmospheres produce ceramics with lighter, reddish interiors.
Studying Pottery
Most of the pottery that archaeologists find is broken in pieces, or sherds.
Whole vessels are rare and found largely in graves and other special situations.
Archaeologists use pottery sherds to gain as much information as possible about the vessels.
The three basic levels of analysis in ceramic studies are the visual identification of macroscopic features, the microscopic identification of petrographic characteristics, and instrumental identification of chemical characteristics.
The initial steps in analysis deal with sorting.
Archaeologists have developed ceramic typologies for most time periods and many places.
More detailed analyses of prehistoric pottery focus on form, function, and style.
In addition, ceramics provide substantial information on group interaction and social organization.
Initial Sorting
Archaeologists normally study pottery sherds.
The sherds from an excavation or survey are usually washed and sometimes numbered.
Sherds are then initially sorted using several criteria.
An important distinction is made between rim sherds and body sherds.
Rim sherds include part of the rim or mouth and can tell a lot about the vessel.
Rim sherds indicate how the pot was finished and how big the vessel was.
Rim pieces often are more heavily decorated than body sherds.
Body sherds are rimless pieces of the pot that are useful, but less informative.
A variety of terms are used to describe a pottery vessel in addition to rim and body.
The base of the pot provides a good indicator of the overall shape.
The shoulder of the vessel is the transition zone where the shape changes as the body ends and the neck begins.
The neck is the zone between the shoulder and the rim.
The collar is an area around the rim that is present only if additional clay has been added to this area to make it thicker.
Attributes of Form and Function
One of the goals of ceramic analysis is to reconstruct the size and shape, or form, of the original vessel.
This information can tell us about the possible function of the vessel and provide additional information on manufacture and style.
There are specific techniques for the analysis of the various elements of the vessel.
The diameter of the orifice is a good indicator of the overall size of the pot.
Pottery had many functions in the past—for storage, cooking, serving, drinking, straining, washing and other purposes.
These uses are important indicators of past human activity, but determination of the function of prehistoric pottery is often difficult.
Size and shape provide clues about the use of a vessel.
Context and the kinds of things found with it provide some of the best indications of how a container was used.
Other types of analysis can reveal further information about ceramics.
Residues on pottery are found in several forms and can reveal both use and contents.
Some indication of use can be seen in the wear and damage to a vessel.
An invisible residue can also be recovered in some cases from the interior clay of the pottery itself.
Science in Archaeology: What's Cooking?
Tybrind Vig is a remarkable underwater archaeological site in Denmark, dating from the Mesolithic period, approximately 4500 B.C.
Although the inhabitants were hunter-gatherers, they also made and used distinctive pointed-base pottery vessels.
Traces and residues from heating and cooking have been preserved on some of the pots.
Attributes of Style
Stylistic variation is important in archaeology for studying changes in artifacts over time and space.
Stylistic attributes in pottery are those characteristics that reflect choices that the potter made in production.
Design elements and decoration are most frequently the focus of analysis in archaeology.
One way to visualize stylistic variation is to consider a series of pottery vessels from a particular area and time span.
Patterns of style in ceramics can reflect identity, social organization, and ideology.
Style in pottery can reflect individual or group choices and these choices may be intentional or instinctive.
James Deetz (1930-2000) was one of the first archaeologists to try to connect ceramic styles with past social organization.
He focused on a large assemblage of pottery from three time periods at a large Arikara Indian site in South Dakota.
Deetz suggested that changes in style reflected changes in the social organization of the group that was influenced by European contact.
Archaeological Thinking: Iroquois Pottery
Robert Whallon recorded the presence or absence of several stylistic elements on prehistoric pottery from New York State.
This pottery came from a series of sites spanning a 400-year period that ended at approximately 1500 AD.
He found that social contact among villages likely decreased over time.
Provenience Studies
Another important kind of ceramic study involves the investigation of provenience or source of pottery.
Determination of the place of origin of ceramics allows researchers to understand various aspects of culture.
Several types of information can be used to investigate provenience.
The kind of temper, vessel shape, or design motif can sometimes provide clues as to place of origin.
Composition can be investigated by a number of methods.
Ceramic Petrography
Ceramic petrography is a useful microscopic technique to identify the physical composition of pottery sherds.
Example: Icehouse Bottom
Icehouse Bottom in Tennessee is a village settlement from the Hopewell period, dating to approximately AD 175.
The site contains a number of chert blades from a source in south-central Ohio, more than 250 miles away.
Petrographic studies of pottery from the site document other exchanges.
Ceramic Composition
The chemical composition of pottery is an important clue as to its provenience.
A variety of methods have been used to measure chemical composition.
Science in Archaeology: Salado Polychromes
Salado polychrome was the one of the most common types of pottery in the American Southwest between AD 1275-1450.
The style is distinguished by black and red designs painted on a white background.
There are three recognized groups of this Salado polychrome.
Both decorated and undecorated pottery was made and used in the Tonto Basin.
Undecorated pottery was made using the paddle-and-anvil technique and comprises about 75% of the pottery.
Decorated ceramics were made using the coil method and were then scraped and polished.
Ceramic human and bird effigies were also produced.
In addition to Salado polychrome, a variety of "foreign" pottery was found in the Tonto Basin.
There are two possible sources for the Salado polychromes.
The pottery could have been made in many different places.
The pottery could also have been centrally produced and exported long distances.
Mineral and chemical composition of the pottery was analyzed.
The early Salado polychromes were made elsewhere and brought into the Tonto Basin.
The later Salado pottery was made in the Tonto Basin and exchanged outward toward the west.
