Eoliths
An eolith is not an artefact. Eoliths are stones fractured by natural processes, which can resemble deliberately-fashioned tools. These eoliths show the range of stone-flaking that can occur naturally.
In deliberate tool-making, a stone is shaped by striking it near the edge, breaking off a flake. The edge of the stone must be acute-angled—measuring 90 degrees or less—and the flintknapper delivers the flake-detaching blow behind a lump or ridge on the stone’s face. But natural stones often have acute-angled edges, and when natural processes cause stones to hit each other forcefully, flakes can be broken off. This most often occurs in tumbled river gravels and beaches, or by rocks bouncing off each other as they roll down steep slopes. Eoliths can show some features of purposeful tool manufacture.
Archaeologists are trained to identify purposeful toolmaking when stone-flaking features are highly patterned, as seen on the scars on cores, or the attributes of flakes deliberately struck from cores. The patterning is obvious for complex stone tools, but sometimes the patterns produced in random rock-tumbling can mimic simple stone tools. Because of this, early antiquarians and archaeologists sometimes mistook naturally-flaked stones from stone tools deliberately produced by people, and the vociferous argument over whether they were natural or cultural objects obsessed researchers for decades in the early 1900s. Some of the first controlled experiments in stone-flaking were designed to distinguish between eoliths and the deliberate stone-flaking by our earliest ancestors.
