Knapping by the River

Preservation Archaeology Blog
Jorge Barceló, University of Arizona

(June 29, 2022)—Today [6/10/22] was my first day of experimental archaeology with Allen Denoyer, along with Aleesha and Tots. After a short, steep hike down to the San Francisco River, we sat on the bank and Allen began to show us the basics of flintknapping.

First, we selected our hammerstone and obsidian nodule from the Mule Creek source and looked for a good platform to strike the first flake. The best material for knapping a blade or point would contain a high level of silica, which is what makes up glass and creates sharp edges. Obsidian is volcanic glass.

Hammerstone and obsidian nodule resting on a leather pad that I used to prevent flakes from stabbing my leg and hand.
Hammerstone and obsidian nodule resting on a leather pad that I used to prevent flakes from stabbing my leg and hand.

Ideally, Allen explained, you want to strike on a point that is less than 90 degrees to start removing the cortex (outer layer of the cobble) to reveal the pristine black obsidian. Preparing a platform—the striking point for the hammerstone—is essential to getting good flakes across the core of the nodule. This is done by rubbing down the edges to dull it so it does not crush when struck. The key is to try to control the energy that is transferred from your arm into the nodule/flake, making a bulb of percussion that is seen as waves across the stone.

Allen Denoyer helping Aleesha, Tots, and me one-on-one to find and make good striking platforms.
Allen Denoyer helping Aleesha, Tots, and me one-on-one to find and make good striking platforms.

With a good platform to strike, you can flake off a nice thin piece that will be ready to start pressure flaking with an antler tine. Not every flake will come off perfectly, and many will have humps and ridges that can be taken down with a billet made from the base of an antler. Once the flake is thinned down enough, the billet is used to form the basic shape of the point by beveling the edge to ready it for pressure flaking. A tine made from the distal end of an antler is the ideal tool for removing small pressure flakes that create the final shape of the point. You can then use the tine to make a sharp and/or serrated edge.

This shows the platform on the tapered end and the waves of energy that went through the rock as it was struck.
This shows the platform on the tapered end and the waves of energy that went through the rock as it was struck.
An example of a good deep pressure flake that did not break (as they usually do) when struck off the face of the point.
An example of a good deep pressure flake that did not break (as they usually do) when struck off the face of the point.

After the point is finished, a notching tool—also made from antler—is used to create various styles of notching, such as corner or side, or a combination of both. The notcher can also be used on the edge to flake out even tinier flakes to achieve nice serrated edges.

Here is my point ready to be pressure-flaked.
Here is my point ready to be pressure-flaked.

Once the point is to shape, sharpened, and notched, it is ready to be hafted onto a shaft or handle using pine pitch or lack from creosote.

Here is the finished point among the debitage that resulted from the process of flintknapping.
Here is the finished point among the debitage that resulted from the process of flintknapping.
Here is my finished point on the core it came from. You can see how much material was removed to form it.
Here is my finished point on the core it came from. You can see how much material was removed to form it.

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