Lesson # 4: Mock Excavations
Grades 5 - 8.by Justin Miller/CAP Staff
Overview
Students will practice excavation, note-taking skills, and analysis of artifacts and features in stratified soils at a simulated site.
Objectives/Skills
Students will:
- Carefully excavate soils to uncover features and artifacts.
- Take descriptive notes about features and artifacts.
- Make accurate drawings from direct observation.
- Take accurate measurements of observed.
- Sort and classify found artifacts.
- Draw conclusions about function of features and artifacts.
- Constructed Unit Boxes
- 1-2 buckets (1-5 gallon) per unit box. (for soil transport, storage, sitting, etc.) 5 gallon buckets are one of the archaeologist's best friends!
- 2 measuring tapes (3-5 meter)
- 2 trowels and dustpans per unit (or 1 per digging student)
- 1 sheet of graph paper, ruler, clipboard, and pencil per unit
- 1 level form per level, per unit
- Personal notebooks/journals to record thoughts and ideas
- Optional equipment: gloves, foam knee cushions, whisk brooms, camera for documentation, garden sprayer tank (for soil preparation), 8x8' soil tamper
Preparation
- Choose a large, open area in which to set up the excavation boxes.
- Prepare a sketch of the "site." on graph paper. Choose either a prehistoric or historic site (or both if you are ambitious) and decide which features you will include. The key to a good simulation is creating believable features. Scattering artifacts creates a simple treasure hunt and does not provide the opportunity to discover a rich martix of form, function, context, complex observation, analysis and spacial relevance that a feature or series of related features provides. You can go a step further and try to recreate part of a real site. If you can find a site-map of a professionally excavated and documented site with a scale, that will work. Sketching the features in higher detail is also recommended. If you can aquire more detailed maps of a real feature, you can use that. Not only will it help you in the creation of the feature, but you can use the drawing as a reference for students after they uncover the feature. Sometimes excavation can be a destructive process.
- When the site is sketched, choose where the units will intersect. Having used graph paper, drawing in the units' locations should be easy. Remember units are 1x1 meters (~3x3ft).
- Lay down the "sub-soil" first, using a tamper and/or a sprayer to compress and pack it down. To maintain visible and texture differences between the soil levels, it's best to use sand or a sand mixture for the sub-soil. It may take a few sessions of spraying and tamping to achieve a natural soil feel. 5-8 centimeters are recommended.
- Using your drawings, create any of the feaures that will intrude into the subsoil. Hearths, storage pits, privies, wells, and foundations all usually intrude into older soil horizons.
- Start laying down the next soil horizon, placing any artifacts in the soil as you build it up. Make sure to fill in and around your features and pack it tightly. Try using a darker loam for the next soil horizon to help differentiate it from the sub-soil. 3-5 centimeters are ideal for the upper soil level.
- Using a sprayer, evenly add water to the soil, and tamp it down as before. Multiple tampings may be necessary.
- Repeat the last 2 steps if you wish to create a third soil level, again making sure to use a soil with a different color and texture. Two horizons are usually more than enough for a group for a one-day session.
- Cover with a plastic sheet or tarp. This will keep the soils from drying out and loosening up. Leaving it overnight will allow the soils' moisture to diffuse as well, making for a less muddy experience.
Step by step in photos...
Create a base of "sub-soil" with light-colored sand. Having a different color and texture helps excavators to identify the different strata.
Make a 3-6 cm base of sand and tamp it down. Using a sprayer helps to settle the sand particles and makes for a more believable soil matrix.
Start your feature construction by digging out a little of the subsoil. This feature will be a hearth, or fire-pit.
Place your artifacts and materials in the depression, and make sure to keep things nice and packed-tight.
When you are done creating the feature, make sure some soil gets packed in and around the items to ensure it's stable and solid.
A pattern of smaller features can tell a bigger story. This feature will be a section of a long house.The structural posts were driven into the ground and eventually rotted or burned, creating circular stains in the soil.
Fill each mold with a mix of charcoal and topsoil to make it readily visible as a feature.
Place some artifacts on the top of the soil level, but not in the post-molds. Artifact's are not commonly found inside the post-molds, but are often found in abundance on the inside of the structure their posts helped to support.
Whatever features you included in the lower levels, make sure to include a good level of topsoil. Seed this level with some artifacts they expect to find, and maybe some very recent artifacts, such as bottle caps, recent coins, or anything that would help drive home the idea of superposition, where the higher level is most recent.
Start your feature construction by digging out a little of the subsoil. This feature will be a hearth, or fire-pit.
Note
If excavation of soils at your location is possible, it may be possible to avoid construction of unit boxes and the use of entirely procured soil. It is encouraged that the boxes contain at least two strata of soils. Since it is possible that your site may have naturally stratified soils, you may be able to extract and separate them. To lay units out in this fashion you will need gutter spikes (large nails) and string to outline.
Core Procedure
- Students should write down observations of the surrounding area. They should write down any thoughts on what activities may have occurred at the site area in the past.
- Break the students up into groups, with 2-3 per unit being ideal. One student can screen while the other two trowel-scrape the soil. Novice excavators are prone to poking, gouging, chunking, and otherwise digging too deeply, too quickly. Trowels should be used to carefully scrape down through the soil over a wide area. Explain it as "pulling off the layers like sheets from a stack of paper" as opposed to taking it out in blocks.
- A student from each group should record the site name, unit number, group members' names, and date on the level form.
- Using the datum string, measuring tape and line level, each student should record the starting depths in each corner of the unit on the level form.
- As the students trowel down through the first level, they should put all found objects into one bag. A tag should be written out for each level/bag of artifacts.
- When students excavate to the levels of the prepared features, extra care should be taken to ensure the form and arrangement of the feature does not get scrambled. After features become visible and cleared by students, pictures can be taken, and a drawing should be completed in the box on the level form, oriented correctly to the page. Students should write in their notebooks what they think the feature is and what activites it arose from.
- After the top level of soil has mostly been scraped from the subsoil, students can end excavations. Artifacts are rarely found in the subsoils here in North America, as they usually correspond to the Pleistocene epoch, when few if any humans were living on this continent.
- Hopefully, the soils can be easily separated on the back-dirt pile for storage or re-use. You can put the soils in piles or buckets for storage. If you leave them outside over the course of a year, they will erode away, helping to level the surrounding area!
- Have the students pack up all the gear and collect notes and artifacts for discussion.
- Gather the groups together to discuss the findings. Have students compare their artifacts, describe the features they found and any conclusions they could draw from what they found about what went on at the site. If a projector, or a black or white board is available, showing your original site sketch might help students to draw more conclusions about the overall function of the site.
Additional Activities
- Have the students map in the site with a compass, protractor, ruler and graph paper, and a 50-100 meter tape measure. Standing at a datum point, use a compass and tape to identify points on the corner of each unit. Use the angle from the compass to find the angle and distance on the page with the protractor and ruler. Compare your own map with theirs to see how accurate (yours or theirs!).
- If you opted to lay the units into the ground, only put in two nails and have students use the Pythagorean Theorem to verify the missing corners.
- Have students find the volume of soil removed from a unit by using the formula: Volume=length x width x height.
- Have students measure and weigh artifacts and create a system for labeling and/or classifying them. (historic/prehistoric, artifact type, color, shape, material, etc.)
- Students can pick out their favorite artifact and make a detailed drawing in their notebook.
- Students can make an illustration of how they think the site looked when it was occupied.
- Have the groups record and graph (pie chart, graphs, etc.) the number of artifacts found in each unit of the site, or the number of each artiface type found.
- Create a statistical analysis of the site and find the mean number of artifacts found per unit, median number per unit, or mode of all units.
