Historic Archaeology is the study of people who lived during the past 200 years or so by looking at the artifacts they left behind. An artifact is anything made or used by people. An artifact can be anything from a 10,000 year old stone tool, to the pop can you recycled after yesterday's lunch.
Just as you need a licence to drive a car, Archaeologists have to get a licence before they can dig (or excavate) a site. Each licence is good for one site and one year. When she gets a licence, an Archaeologist agrees to write a site report, telling the world what she found on the site.
Once the Archaeologist has received the archaeological licence, she is ready to survey the site. Surveying is a lot like taking a huge piece of graph paper and placing it down over the site. The graph is called a site grid. By digging on a site grid, you can be sure that all of the squares or units on the site are the same size.
The next step is to remove the sod and topsoil, which is usually the modern grass level. Sod is removed with shovels by digging up the soil in narrow and shallow strips. Shovel shining is removing the topsoil by skimming the surface with the shovel blade, taking a thin layer of soil off the surface.
Now the excavation is ready to begin. Sites are dug in square units. The size of the unit is usually decided by the Archaeologist. Special attention is paid to layers and features.
Believe it or not, the ground is arranged in layers, kind of like a layer cake. When you find a layer in your unit, it will usually cover the whole floor of your unit. You can tell when you've reached a new layer when the colour of the soil, or its make-up (texture) changes. Archaeologists dig with trowels, exactly like those used by a bricklayer but smaller (20 cm. or 9 inches long). A feature is an artifact that is too large to move. A feature might be anything from a filled in pit to a foundation wall or floor.
Dirt is sifted through a screen to make sure no artifacts were missed while digging. Artifacts found in each layer are bagged separately from the ones found in the layer(s) above and below it. Detailed notes, photos, and maybe even videos are taken about everything that is done or found on the site while digging.
If you find a feature while you're digging, you will have to draw a top (topographical) plan of it. A top plan is a drawing that gives you a bird's eye view of the feature. It is drawn to scale, which means that it is measured as it is drawn, and shrunk down to fit on a piece of graph paper. A good scale for a top plan is for 10 cm on the ground to equal 1 cm (or one square) on the graph paper. The feature is then dug out separately from the layer(s) around it. Artifacts found inside the feature are kept in a separate bag from the ones found in the layer(s) around it. Once the feature has been dug out, you have to draw a cross section of it. A cross section is a drawing that looks as if you've cut the feature in half. It tells the Archaeologist what shape it was, and possibly, how it was created and destroyed. A cross section is also drawn to scale.
A unit is usually dug until you find subsoil. Subsoil is different in each area, but it is usually a hard clay or sand. Subsoil is sterile, which means there are no artifacts in it. Sometimes, if you are lucky, you might find some non-European features in the subsoil. These are features made by First Nations (often Iroquoians in Toronto), more than 300 years ago. Once you find subsoil in your unit and you are sure it is sterile, you can draw a profile of the unit. A profile is a drawing of the walls of your unit showing the layers (and features) you found as you were digging. A profile is also drawn to scale.
Once the profiles have been drawn and photographed, you can backfill the unit. When you backfill, you are filling in the unit so that the area can be returned to the way it was before you started digging.
Artifacts and notes are taken back to the lab for analysis. It is in the lab that the Archaeologist looks at all of the information found in the field and tries to piece it all together. Analyzing a site is like putting together thousands of small pieces of a huge puzzle to see what it looks like. Once the puzzle has been put together, the Archaeologist tells what she thinks it means in the site report.