Johan Kamminga

The formation of flakes

An understanding of the mechanics involved in flake formation provides an opportunity for deriving more behavioral information from flake and flake scar morphology. The mechanics of flake formation are directly relevant to the identification of prehistoric flaking techniques and stone tool use. In this paper we provide a model of flake formation that accounts for much of the variation in flake morphology. Flakes can form in a number of ways and despite popular belief they are not all of the conchoidal variety. The bending flake is common in use wear though it is often misidentified as a conchoidal flake. A third major type of flake, the compression flake, is a common product of bipolar impact. To account for the wide variation in flake morphology we follow a tripartite scheme of flake formation comprising initiation, propagation, and termination phases, within which different mechanisms can operate.

Mechanics of pre-industrial technology : an introduction to the mechanics of ancient and traditional material culture

List of figures List of tables Preface 1. Introduction 2. Basic mechanics 3. Fluids and solids 4. Machines 5. Structures 6. Stone tools 7. Projectiles 8. Land transport 9. Water transport 10. Musical instruments 11. Epilogue Appendixes References Index.

Finials on stone flakes

Abstract When a conchoidal flake is detached from a stone the fracture can either terminate at a small angle to the stones surface, creating a feather flake, or turn to end at rightangles, creating a hinge or step flake. If a crack turns towards the surface of the stone its path is unstable, and the crack often turns once again, to propagate parallel to the surface of the stone and form a retroflexion or an inflexion on the end of the flake. The retroflexion on the end of a hinge termination has long been recognized, but the inflexion, and its combination with a retroflexion to form a pseudo-bifurcation, has not. Recognition of these finials is important in use-wear analysis for the accurate identification of the various flake scar types and the determination of stone tool function.

When did Homo sapiens first reach Southeast Asia and Sahul

Anatomically modern humans (Homo sapiens, AMH) began spreading across Eurasia from Africa and adjacent Southwest Asia about 50,000–55,000 years ago (ca. 50–55 ka). Some have argued that human genetic, fossil, and archaeological data indicate one or more prior dispersals, possibly as early as 120 ka. A recently reported age estimate of 65 ka for Madjedbebe, an archaeological site in northern Sahul (Pleistocene Australia–New Guinea), if correct, offers what might be the strongest support yet presented for a pre–55-ka African AMH exodus. We review evidence for AMH arrival on an arc spanning South China through Sahul and then evaluate data from Madjedbebe. We find that an age estimate of >50 ka for this site is unlikely to be valid. While AMH may have moved far beyond Africa well before 50–55 ka, data from the region of interest offered in support of this idea are not compelling.