This is going to be a slightly different post... about lithics!
What are lithics? Well, they are tools made from stone dating back thousands of years. These tools can be as big as your forearm, or as small as your little finger. Some were used as arrow heads, spear heads, or knives, and show notches that were used to help bind them to handles and arrow shafts. Others were large enough to not need a handle, and the cutting edge is only on one side.
Check out this handy chart of lithics from the southeastern United States (Anderson, Smallwood, Miller 2015)!
These include points, such as arrow heads and spear tips, as well as scrapers, which are, well, tools used for scraping and cutting. Lithics are what is left when the wood and sinew handles have long rotted away.
Like anything, it takes a little practice to train your eye as to what is a man-made chip at the edge of a stone and what was created by chance (or by farming equipment). The tell tale signs are going to be the ripple and the bulb.
The curve of a flake will look almost leaf-like, with a smooth bump on one side. That bump called the bulb, and it is created by the impact of a chipping tool on a piece of treated stone. This chipping is called "napping."
Stones which were suitable for tools were usually heat-treated. The heat would harden the rock so that it could be fine-tuned into a more useful point or edge. By shaping them with many small and precise hits, the kintetic energy is dispelled outward from the point of impact. One of the other distinguishing features of lithics, is the ripple. The repeated impact made by napping a stone will send shockwaves through the material, creating a ripple as well as a bulb. These impacts are the easiest way to identify a lithic from a rock that was shaped naturally.
In the field, fragments are often all that is left of lithics in areas where construction had come through the area. Finding pieces with ripples but no major bulb, and vice versa, is common. When a rock is broken by being run over, or cracked by excavation equipment, the break does not create bulbs and ripples. This is because that break is created by a large tool, as opposed to a small and precise area of impact.
Further reading:
Anderson, David & Smallwood, Ashley & Miller, D. (2015). Pleistocene Human Settlement in the Southeastern United States: Current Evidence and Future Directions. PaleoAmerica. 1. 7-51. 10.1179/2055556314Z.00000000012.
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