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Petrified wood

In geology, petrifaction, petrification or silicification is the process by which organic material is converted into stone by impregnation with silica. It is a rare form of fossilization. Petrified wood is the most well known result of this process, but all organisms from bacteria to vertebrates can be petrified.

[edit] Process

A major ingredient in the cell walls of wood is cellulose. Under certain conditions, the silica binds to the cellulose; when it crystallizes, it preserves the microscopic structure of wood even after the cellulose is gone.

Petrification is not the same as permineralization. Permineralized animal or vegetable remains have their original pore space infilled with minerals. In petrification, while the pore space is infilled with minerals, the original material of the organism is also replaced with minerals.^[1]

In the grammar of architecture, the word petrification is often used when discussing the development of sacred structures, such as temples, mainly with reference to developments in the Greek world. During the Archaic (please see Archaic Greece) and early Classical periods (about the 6th and early 5th centuries BCE), the architectural forms of the earliest temples had solidified and the Doric (see Classical order) emerged as the predominant element. A widely accepted theory in classical studies is that the earliest temple structures were of wood and the great forms, or elements of architectural style, were codified and rather permanent by the time we see the Archaic emergent and established. It was during this period, at different times and places in the Greek world, that the use of dressed and polished stone replaced the wood in these early temples, but the forms and shapes of the old wooden styles were retained, just as if the wooden structures had turned to stone, thus the designation petrification for this process.

This careful preservation of the primitive wooden appearance in the stone fabric of the newer buildings was scrupulously observed and this suggests that it may have been dictated by religion rather than aesthetics, although the exact reasons are now lost in the mists of antiquity. And not everyone within the great reach of Mediterranean civilization made this transition. The Etruscans in Italy were, from their earliest period, greatly influenced by their contact with Greek culture and religion, but they retained their wooden temples (with some exceptions) until their culture was completely absorbed into the Roman world, with the great wooden Temple of Jupiter (see Temple of Jupiter (Capitoline Hill) on the Capitol in Rome itself being a good example. Nor was it the lack of knowledge of stone working on their part that prevented them from making the transition from timber to dressed stone.

[edit] In fiction

In fiction, petrifaction refers to turning living beings into stone. This is based on the legend of Medusa (people would turn to stone when they look at her) and has been adapted into many role-playing games.

[edit] See also

• For a list of sites of major collections of petrified materials, see Petrified wood.
• The Rhynie chert, A famous early petrified ecosystem
• Taphonomy - ways that fossilisation can happen

[edit] References

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