The Archaeologists' Toolbox
Archaeologists have an array of tools at their disposal to use before, during, and after excavation. The tools we use depend on soil type, depth of stratum, and the fragility of the artifacts.
Before we begin digging, we lay out a grid system to determine the area of excavation. We use a transit, a survey tool you might see employed by construction workers on the side of the road. It has a small telescope-like eyepiece and is usually perched on top of a tripod. This particular tool gives us an indication of distance and elevation of certain points on the ground.
The most common excavation tool is the trowel. The trowel is used to slowly remove dirt and can keep the stratum level while excavating to see any new features that may appear in the soil. We use brushes, spoons, and dental picks when excavating smaller features. Dirt is scooped into dustpans and dumped in buckets or a wheelbarrow. We use shovels only when a stratum is very thick and there aren't many artifacts. Root clippers and saws are useful when roots intrude into a stratum and impede excavation.
|Jen brushes a badly decomposed rubble feature.|
Strings, tape measures, and line levels are used to record opening and closing elevations of each stratum during excavation. We take these elevations so we know the depth of a particular stratum and how thick it was. We also use the tape measures to map the area that will be excavated on the card that contains all the information about a particular level.
We use a Munsell book--a collection of color swatches with designated numbers and names--to identify the exact color of the soil to be excavated. This allows for relative consistency in recording soil color.
|Jen matches the color of the soil with one of the many shades of brown contained in the Munsell book.|
Dirt must be screened after it is removed from each square. It is either dry screened (we use both 3/8 and 1/4 inch mesh) or water screened (where 1/16 inch mesh is used). Dry screening is the process of putting the dirt directly into the screen and shaking out the dirt over a wheelbarrow. Artifacts are then taken out of the screen and bagged. Water screening is a way to save more of the objects from each layer. We place the dirt in a wooden trough and use a hose to spray it into two screens at the other end.
We separate the artifacts into 1/4- and 1/16-inch mesh. All the material in the screens is saved in bags and later sorted in the lab. We use water screening for strata thought to relate to the late-eighteenth century. We collect two bags of dirt from each layer for flotation (10 x 12 inch bag). Flotation recovers botanical remains such as seeds that would otherwise fall through the screen (see "Flotation 101") We also take soil samples and pollen/phytolith samples to be processed by specialized laboratories.
We map the newly exposed strata after excavation. We put tape measures along two edges of the square and run a third across the middle. We use a plumb bob to make accurate measurements of the points to be drawn in and a ruler to draw the map to a particular scale on a piece of graph paper. These maps are scanned into a computer and digitized (see "Mapping the Distillery Site"). We also take photos--black and white and color slides and digital images--of features before and after they're excavated.
Questions about the tools we use? Stop by the bulletin board!