You must have heard about the Petrified Forest, of how trees from the prehistoric era fell and have become petrified.
Petrification is actually a natural phenomenon which happens to all trees as time goes by. Petrified wood forms when fallen trees are washed down a river and then buried under the many layers of mud, ash and other materials.
Because of being sealed completely the rotting wood becomes deprived of oxygen which is the important ingredient for decay.
As the organic tissues in wood start to break apart slowly, the gaps inside the tree are slowly filled with silica which is a material found in rocks.
Over millions of years, these crystalize inside the wood’s structure creating a stone-like material called petrified wood. Actually, to call wood “wood” at this point is already incorrect. Wood will take on the color of the minerals that have assimilated it.
If copper, chromium or cobalt has remained in the gaps, the wood will have a green-blue tinge. On the other hand, wood that has been penetrated by manganese can have a pink color.
So it would be safe to say that petrification can happen for millions of years. After all, petrified wood is the result of nature’s natural effects. But in reality, wood can be petrified quickly given the right environment.
Wood can petrify quickly
Contrary to belief, wood can actually petrify quickly and certainly less time than it takes for wood to decay in a given environment. Wood can be petrified using two techniques that use volcanic ash. This way, wood can decompose even in the presence of water and enriching the groundwater with silica.
The first process of petrification involves wood decaying in a hot, silica-rich environment. Every molecule of the wood will decompose and will be carried away afterward every molecule lost will be replaced by a molecule of silica. After the process is complete, the wood will become very hard and will change in color.
The mineral impurities in silica will bring about an array of beautiful colors in the final product. And because of the glorious result, the wood may be polished and it becomes a prized piece or a museum piece. Once silicification is complete, no organic material remains.
The light and dark portions of the tree’s growth rings may decay according to different rates, therefore, the tree rings may be preserved if the minerals change color over time. Most of the petrified trees found in the Petrified “Forest” of Arizona are preserved using this technique.
The second petrification technique is total infiltration of the porous wood using silica-rich water. The silica or calcite, or a combination of both will fill up all the pores to prevent complete decay of wood. This preserves individual cells and in many cases, the tree ring pattern can be seen.
The petrified trees found in Yellowstone Park were preserved at this manner with the lovely tree rings readily visible.
Laboratory tests show
We all know now that wood can petrify quickly and several laboratory experiments have found ways in to do this even mirroring natural settings.
For reference, check out Sigleo, 1978 “Organic Geochemistry of Silicified Wood,” Geochimica et Cosmochimica Acta, vol. 42, pp. 1397-1405, and Leo and Barghoorn, 1976, “Silicification of Wood,” Botanical Museum Leaflets, vol. 25, no. 1, Harvard University, 47 pp.
Apart from these wood can also be petrified in field settings as with one experiment where researchers dangled a block of wood inside an alkaline spring in Yellowstone Park. This is to find out what effect this hot, silica-rich environment would have in wood. In just a year, substantial petrification had occurred.
There is also a company that claims to petrify wood for commercial purposes. With these techniques, it is now clear that it does not take millions of years for petrification to happen given the right conditions.
Natural petrification of wood can occur for millions of years but this can speed up. There are new processes and techniques that have proven that you can petrify wood in just a year or so. You must simply provide the ideal environment for petrification to get started.