Old as… ?: Dating Archaeological Sites

Knowing the date of an archaeological site is one of the things that makes it most interesting – when were people here?

Two main types of dating are applied to archaeological sites when possible– relative and absolute dating. Relative dating puts sites or artifacts “in order” by simply determining if one event happened before or after another. A common example of relative dating in Alberta is by using Mazama Ash. About 7600 years ago, Alberta was blanketed in ash after the Mazama volcanic eruption. This ash is still sometimes found today in stratigraphic profiles, buried under other deposits of sediment. When this ash is encountered it can be used as a time marker. Anything below it is older than 7600 years and anything found above it is younger than 7600 years.

Example of a buried volcanic ash (also known as tephra) found during archaeological excavation. The ash is the lightest coloured layer in the profile, between 25 and 35 cm below the surface (between the 1 and 3 on the tape measure).

Relative dates can also be obtained using artifact styles. Projectile points are one of the most common types of artifacts used to relatively date sites. Spearpoints represent the oldest projectile point technology and indicate that the site falls within the “Early Prehistoric Period” (11,200-7,500 calendar years before present), dartpoints are representative of the “Middle Prehistoric Period” (7,500-1,350 calendar years before present) and arrowpoints represent the emergence of the use of bow and arrow in the “Late Prehistoric Period” (1,350-250 calendar years before present). Dates can be further refined within each general time period based on the spear, dart or arrow style.

Absolute dating is more specific than relative dating and provides a more exact date (with standard deviation) of when the site or artifact was used. There are several methods of absolute dating but one of the most common methods used by archaeologists is radiocarbon dating. Radiocarbon dating can be used on organic material such as bone or charcoal. A radiocarbon date can be obtained by measuring the amount of (more…)

Flint Knapping with the Archaeological Society of Alberta

The Archaeological Society of Alberta (ASA) is an amateur organization of over 400 members who are dedicated to promoting, protecting, and preserving Alberta’s heritage. The society regularly holds events that allow the public to actively experience archaeology in the province.

In March the Strathcona chapter of the ASA held a flint-knapping and tool-making workshop in Edmonton. The ASA workshop allowed members to get first-hand experience making the stone, or lithic, tools that are among the most common artifacts found in archaeological sites in Alberta. Prior to the arrival of metals with Europeans in North America, First Nations people created tools such as blades, knives, axes, and projectile points, by knapping stones. Knapping technology is not unique to Alberta, but was used by humans and our ancestors in all parts of the world beginning as early as 3.3 million years ago in Africa. Today many archaeologists practice knapping to better understand the material culture recovered from archaeological sites. Knapping is also a common hobby among archaeologists and non-archaeologists alike.

Creating Stone Tools

First, cores of lithic raw material are precisely broken using hammerstones (stones and antler) to produce large, flat flakes. At the workshop, participants knapped obsidian and dacite, two types of stone that are easy to use for beginners. When knapping, safety is always top priority. Striking stones such as obsidian produces tiny shards of the material, which tend to scatter and can easily cause injury. To prevent accidents, knappers use hand and eye protection, and always have plenty of bandages at the ready. The scattered waste flakes produced when knapping are called ‘debitage’ by archaeologists.

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ASA participants using hammerstones to produce lithic (stone) flakes and debitage.

Next, smaller flakes of stone can be worked into tools. Instead of striking the stone, smaller flakes can be removed by applying consistent force in a process called pressure flaking. In the picture below, a knapper is using a copper pressure flaker to work the edge of a projectile point.

Photo 2

A knapper using a copper pressure flaker to work the edge of a projectile point.

Finally, the knappers were able to haft their new tools onto wood or antler shafts and handles. The stone tools were affixed into the wooden handles using pine pitch, and then fastened using animal sinew and hide glue. In archaeological sites the organic shafts, handles, and fastening materials have usually decayed, leaving only the stone tools behind.

Photo 3

Some of the tools created at the ASA Flint Knapping workshop

Becoming a good knapper takes a lot of patience and practice, and it helps to have a good teacher. If you are interested in learning how to knap stone tools, there will be two knapping events in Alberta this year in July and September.

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Written by: Colleen Haukaas, Archaeological Permits & Digital Information Coordinator.