|Petrified wood is formed
by ancient trees which washed into a river system and
were buried quickly and deeply by massive amounts of sediment and
debris. Lacking oxygen to promote decomposition, the trees maintained
their form for centuries.
The petrified wood on this page
were photographed in Petrified Forest National Park.
As the trees lay buried, minerals such
as silica dissolved from volcanic ash, absorbed into the porous wood
over hundreds and thousands of years to eventually crystallize within
the cellular structure, replacing the organic material as it broke
down over time. This process can maintain much of the original detail
of the wood such as rings, cellular structure and wood grain. When the
process is complete, petrified wood is made up of almost solid quartz
weighing 200 pounds per cubic foot. The different colors are produced
by impurities in the quartz, such as iron, carbon, and manganese.