Pressure flaking is a retouching technique that was used by prehistoric toolmakers to shape stone tips. They pressed the narrow end of a tool close to the edge of a piece they were working on to create rectangular, parallel marks; these are considered the hallmark of pressure flaking. This technique allowed them to more finely control the final shape and thinness of the tool edge than direct percussion could, and yielded sharp, thin, V-shaped tips with straight edges. The earliest evidence for p[...]

via Toolmaking technique 55,000 years older than we thought