Lesson: Archaeological Grid Lines

 

Objectives:

Review of Cartesian Coordinate System

 

Materials:

·        The Piedmont Site overhead and worksheet

·        The Grid Sheet

·        Copy of The Piedmont site with grid sheet over it.

·        Artifact Location Record

 

Setting the Stage:

Have the students imagine they are a team of archaeologists who have found an archaeological site. Artifacts—including projectile points, pottery sherds, and stone flakes--are scattered on the surface of the ground. They want to make a map of the site. How might they accurately record the location of the artifacts? Have the students brainstorm ideas.

 

Procedure:

1. Provide Background information on grid line use in archeology.

 

2. Project the map of "The Piedmont Site" and explain this is a site they have found in central North Carolina. Overlay a transparency of "The Grid Sheet" and align it to the site by matching the site datum points. Explain that they, as archaeologists, will record exact places where artifacts are found. Share background information about the importance of gridding a site for current and future study.

 

3. Pass out copies of The Piedmont Site with the grid overlay as students get into teams of 3.

Note: A simplified alternative to the above procedure is to have students overlay "The Grid Sheet" to "The Piedmont Site" and

hold them up to the light. "The Grid Sheet" already has named squares.

 

4. Distribute to each team the "Artifact Location Record." On it, students will record the grid unit designation and count and name the artifacts in each grid unit. If no artifacts are found in the unit, students should put "0." If an artifact is on a grid line, the student must choose which grid square to record it in. An artifact cannot be recorded in more than one square. One student counts the Flakes, one student counts the Sherds, and the third counts the Points. After the students record the artifacts found in each one write the exact location of each artifact found. (Example: (3.3,8.2) or (5.2,3.8)

 

 

5. Following the procedure of scientific inquiry ask:

• What do you notice about the distribution of the potsherds? (Note your observations.)
• Why is there a concentration of potsherds in part of the site? (List some inferences.)

     Choose one inference and formulate a hypothesis from it. Describe how the hypothesis might be tested. Here is an example: There are a lot of potsherds in one location. We might infer a pottery vessel broke here. If all of the sherds have similar attributes and fit together, then we could accept the hypothesis that a vessel broke in this location. What other reason could explain the concentration of sherds? The students will not be able to actually test the hypothesis without access to the artifacts. This exercise is designed to have them think like archaeologists. Conduct a similar inquiry using the stone flakes or other artifacts.

 

 Evaluation

Students turn in their completed "Artifact Location Record" for evaluation.

 

Closure

Summarize the importance of why archaeologists grid archaeological sites to assist with accurate recording and making inferences from data, now and in the future.

 

Background Information

Once a site has been dug (or in the case of sites with no depth, the surface artifacts have been collected), it is gone forever and can never be replaced with another just like it. Because sites are destroyed during collection or excavation processes, archaeologists record them in detail to preserve the context of all the artifacts and structures. Archaeologists in the future can study an excavated site only if good notes and maps are made.

 

One way archaeologists preserve context on paper is through the use of the rectangular grid, or Cartesian coordinate system. The first step in the excavation process is to establish a grid. A site datum is set at an arbitrarily chosen location and is designated as (0,0). Two perpendicular axes or lines intersecting at the site datum are then established and a rectangular grid is superimposed over the entire site. Each square on the ground is marked with numbered stakes in the corners, so that each square or grid unit has a unique "name" referred to by its coordinates. The coordinates indicate the distance of a given point

north, south, east, or west from the site datum.

 

Once the grid is established, all artifacts and structures are measured and recorded using the system. Before excavation actually begins, all artifacts visible on the surface are collected and their locations on the grid are recorded. As the excavation proceeds, materials found under the surface are similarly recorded and collected. When the archaeologist returns to the laboratory, the maps and the data recorded in the field can be used to make inferences about past events and the lifeways of the site's inhabitants. If the exact location of each artifact transported back to the laboratory is known, then the object can be tied to its

context within the site.