Silcrete
Encyclopedia
Silcrete is an indurated soil
duricrust
formed when silica is dissolved and resolidifies as a cement. It is a hard and resistant material, and though different in origin and nature, appears similar to quartzite
. It is common in the arid regions of Australia
, often forming the resistant cap rock on features like breakaway
s.
In Australia, silcrete was widely used by Aboriginal people for stone tool manufacture, and as such, it was a tradeable commodity, and silcrete tools can be found in areas that have no silcrete groundmass at all, similar to the European use of flint
. Tools made out of silcrete are difficult to make with flintknapping techniques. This has led some researchers to conclude that silcrete may have been heated to aid with creating proper flakes prior to knapping. This process may have been the first use of so called pyrotechnology by early mankind.
http://www.scientificamerican.com/article.cfm?id=cooked-results-modern-toolmaker
In Africa, researchers have determined that two types of silcrete tools were developed between 60,000 and 80,000 years ago.
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
duricrust
Duricrust
Duricrust is a hard layer on or near the surface of soil. Duricrusts can range in thickness from a few millimeters or centimeters to several meters....
formed when silica is dissolved and resolidifies as a cement. It is a hard and resistant material, and though different in origin and nature, appears similar to quartzite
Quartzite
Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink...
. It is common in the arid regions of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, often forming the resistant cap rock on features like breakaway
Butte
A butte is a conspicuous isolated hill with steep, often vertical sides and a small, relatively flat top; it is smaller than mesas, plateaus, and table landform tables. In some regions, such as the north central and northwestern United States, the word is used for any hill...
s.
In Australia, silcrete was widely used by Aboriginal people for stone tool manufacture, and as such, it was a tradeable commodity, and silcrete tools can be found in areas that have no silcrete groundmass at all, similar to the European use of flint
Flint
Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark grey, black, green, white, or brown in colour, and...
. Tools made out of silcrete are difficult to make with flintknapping techniques. This has led some researchers to conclude that silcrete may have been heated to aid with creating proper flakes prior to knapping. This process may have been the first use of so called pyrotechnology by early mankind.
http://www.scientificamerican.com/article.cfm?id=cooked-results-modern-toolmaker
In Africa, researchers have determined that two types of silcrete tools were developed between 60,000 and 80,000 years ago.