Other Names: pseudo-quartzite, billy, shin-breaker, gibber, gannister etc.
Silcrete is a silica-rich (greater than 85%) duricrust that forms as a result of low temperature silification of a weathered regolith, bedrock and/or
sediments. It forms at or near the surface and often contains plant stem and root casts.
Generally silcrete forms in hot arid environments where infrequent waterlogging causes silica to dissolve and be redeposited to cement soil grains together.
It can also be associated with basaltic vulcanism.
It often becomes a resistant caprock up to several meters thick on the top of mesas, buttes and ridges, having first formed in low areas, the surrounding land
is weathered away and lowered. This is termed an 'inverted landscape', the rocks of low valleys becoming the high areas.
Although chemically and physically similar to chert, meta-quartzite and some other rocks silcrete has a different origin.
Silcrete weathers spheroidally to produce boulders and angular fragments.
Distribution in Australia: Found extensively throughout inland Australia (ground water and pedogenic silcrete) and east of the Great Dividing Range (sub-basaltic silcrete)
Uses: Fine grained silcrete was used by Aboriginal people in the manufacture of stone tools. It is difficult to work into a desired shape and was often heat treated
by prolonged baking in a high temperature fire to improve its workability. Silcrete was a tradable commodity.
Sources: Encyc Britanica, (http://www.britannica.com/EBchecked/topic/544043/silcrete)
Wikipedia, (http://en.wikipedia.org/wiki/Silcrete)
Australia, A Land Before Time, (http://austhrutime.com/silcrete.htm)


Silcrete is a silica-rich (greater than 85%) duricrust that forms as a result of low temperature silification of a weathered regolith, bedrock and/or
sediments. It forms at or near the surface and often contains plant stem and root casts.
Generally silcrete forms in hot arid environments where infrequent waterlogging causes silica to dissolve and be redeposited to cement soil grains together.
It can also be associated with basaltic vulcanism.
It often becomes a resistant caprock up to several meters thick on the top of mesas, buttes and ridges, having first formed in low areas, the surrounding land
is weathered away and lowered. This is termed an 'inverted landscape', the rocks of low valleys becoming the high areas.
Although chemically and physically similar to chert, meta-quartzite and some other rocks silcrete has a different origin.
Silcrete weathers spheroidally to produce boulders and angular fragments.
Distribution in Australia: Found extensively throughout inland Australia (ground water and pedogenic silcrete) and east of the Great Dividing Range (sub-basaltic silcrete)
Uses: Fine grained silcrete was used by Aboriginal people in the manufacture of stone tools. It is difficult to work into a desired shape and was often heat treated
by prolonged baking in a high temperature fire to improve its workability. Silcrete was a tradable commodity.
Sources: Encyc Britanica, (http://www.britannica.com/EBchecked/topic/544043/silcrete)
Wikipedia, (http://en.wikipedia.org/wiki/Silcrete)
Australia, A Land Before Time, (http://austhrutime.com/silcrete.htm)


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