Researchers have concluded that Stillbay people prepared the silcrete stone out of which they made their stone tools with preheating in human made fire to increase its workability.
12.
Fine-grained stone such as silcrete and quartz make up a large percentage of Howiesons Poort artifacts than in both earlier and later Middle Stone Age cultures.
13.
Groundwater silcretes typically formed in more localised, topographically lower settings such as valley bottoms and slopes, whereas pedogenic silcrete tended to form extensive sheets over very large areas.
14.
In South Africa at Pinnacle Point researchers have determined that two types of silcrete tools were developed between 60, 000 and 80, 000 years ago and used the heat treatment technique.
15.
Elsewhere, beekite has been compared to silcrete, indicating a break in sedimentation, where it occurs as encrustations on clasts of carbonate rock in the Palaeocene alluvial fan deposits of central Anatolia.
16.
The evidence includes some combination of carbonized roots and rootlets, rhizoliths, illuvial clay cutans, silcrete-like silica cements, and the leaching and alteration of the sandy sediments by weathering and plants.
17.
Experiments involved slowly heating silcrete stones to ~ 350 �C . Thermoluminescence confirmed that all stones analysed ( limited to 26 in number due this being a destructive process ) had been heated to this temperature.
18.
The peoples of the African Middle Stone Age ( MSA ) showed a preference for silcrete tools, sourcing the material from up to 200 km to use in place of more accessible quartz and quartzite.
19.
It can sometimes be found in dry and rocky watercourses, but is most often found in clusters on rocky jump-ups and colluvial slopes of rocky mesas with weathered silcrete rocks and loamy soils.
20.
Formation in this are from the Permian : Boniches, Alcotas, an unconformity followed by Hoz de Gallo Conglomerate, this is capped by sandstone and silcrete at another unconformity marking the end of the Permian.
