What is petrifaction? - Some facts

petrified wood

Petrifaction is the process in which materials such as wood become rock formations. This happens through a replacement of the original substance by minerals of various types. The best known examples are the Petrified Forests found in Arizona. These are classified as a kind of fossil.

The word petrifaction explains what has occurred. Petri- means "rock," and -faction refers to "make." Thus petrified wood becomes "rock made from wood."

Wood started petrifying millions of years ago when conifer trees lay decaying. Min­erals including silica, pyrites, and dolomites in water solution penetrated the cells of the wood. The minerals, separating from the water, left all spaces filled with solid rock. These logs have thus been preserved in forms very much as they originally appeared. Branches and leaves have, of course, disappeared.

These petrified logs are three and four feet in diameter and some are over 100 feet in length. Their colors run through grays and browns with variations of shading as well as patches and streaks brought about by various combinations of minerals.