Obsidian biface made by flintknapper J. Jeffrey Flenniken in 1982.

J. Jeffrey Flenniken is an archaeologist and flintknapper based in the United States.  He was a student of Don Crabtree, and through the 1980s he taught the Washington State University flintknapping-based field school for students studying stone artefact analysis techniques.  Flenniken uses traditional tools—particularly soft hammerstones—in his replication studies.  He has used experimental flintknapping to research Folsom point manufacture, Great Basin projectile points, and pressure blades from eastern Siberia and Mesoamerica, among many other technologies.

Flenniken prefers using soft hammerstones to reduce stone into bifaces when replicating North American technologies.  The biface in this model was made during a flintknapping demonstration in 1982 at the University of New England in Australia.  The demonstration was filmed and is available here.