The most abundant traces of human occupation in the Namib Desert are stone artefacts. These are easily recognised as isolated finds and as surface scatters on the gravel plains of the Namib. Stone artefacts were made by removing flakes from a selected core, or block of raw material, using precise blows that leave unmistakeable evidence of human manufacture. Similar breakage patterns very rarely occur in nature. Over time, methods of artefact production became more sophisticated and the different techniques of flaking provide some indication of age. Other artefacts include metal items and objects obtained through trade such as glass beads, porcelain etc as these are a helpful indication of age.