by Colleen Boyle – CART Archaeological Technician
Recording field notes is one of the most important things archaeologists do in the field. Field notes often represent the final record of what was excavated, as archaeological excavation is an inherently destructive process. Along with written descriptions of what archaeologist’s find and see, visual records, such as photographs and scale drawings, are equally important. The process of drawing or mapping is a clear and precise way to accurately record an area such as a test unit or feature in a way that gives the archaeologist more control than a photograph alone. Photos can be a great tool to quickly record a lot of visual data in the field but they can be blurry, washed out from the sun, or tilted at a strange angle. Drawn maps allow the archaeologist to create a representation that records exactly what they see in the field.
The process of mapping a test unit is often simple, although sometimes it can be much more complex. Here at CART our archaeologists use a scale in centimeters since we measure our test units by the meter. We use the squares of a grid on a piece of graph paper to represent a certain measurement on the ground. The area that each square represents varies depending on the scale being used. A 1×1 meter test unit fits easily onto the page where one inch of graph paper represents 20 centimeters along the test unit. By assigning points within test unit, shapes of the features like soil stains and stones can be drawn accurately. There are two main types of drawings done in the field: planviews and profiles.
A planview drawing is essentially a to-scale image of what the area such as a test unit looks like from above. A planview drawing is similar to a roadmap, showing the horizontal boundaries of things often within a particular test unit or feature. When the soil at the base of the excavation contains subtle color and texture changes the best way to record this is through drawings and lots of notes about what you see! Photos aren’t the best tool to show depth or changes in elevation or soil texture within the unit, but drawings allow for those sorts of differences to be added with a key so that others can understand what is being represented.
Planviews can also be utilized in larger scale drawing or something more complex like a stone foundation or a brick floor. When a large feature like a cellar is found, the group of test units surrounding that feature can become too large to use a camera to record it. When this happens a planview is created to accurately map the feature in a way that would be very difficult to obtain via a photograph. Sometimes there are test units that contain lots of rocks or bricks making a more complex image, planviews are one of the best ways to ensure that the measurements are recorded correctly.
Note the north arrow and the scale. Cardinal directions, scale, project, site and location information are vital to every map.
The second type of drawing is called a profile. A profile follows the same idea as a planveiw drawing, only think of a profile like a face of a building, it is a map that shows the layering within a test unit’s walls. These walls can be just as important as the base of a test unit because profiles are the best way to show the stratigraphy an archaeologist encountered while excavating a unit. The process of mapping a profile is similar to that of a planview, but vertical as well as horizontal measurements are recorded. Subtle soils changes, plowscars, pit features, or types of soils staining indicating depth can be seen in the walls of a test unit. Vertical measurements are taken by measuring down from a known elevation or datum. At CART this is usually done using a line level and a chaining pin.
Other important elements to these map types include the key and soil color description. Just as in any map a key is very important to understanding the different elements being represented within the drawing. Things like bricks, stones, tree roots, elevation change, soil inclusions like charcoal, and layer changes are often seen in these drawings. In some situations, artifact location is very important. The artifact or artifacts will be left in place to be mapped so that its exact location can be noted. Soil colors are also necessary to understand stratigraphy and are usually a main focus of profile drawings. Archaeologists will use the Munsell soil color chart to try and match what they are seeing to a previously assigned code and color description, this way there is a standardized list of color names hopefully eliminating any confusion or misinterpretation through mapping.