In Petrified Forest, Arizona, trunks are divided into large chunks with surprisingly sharp faces. One could imagine the passage of a chainsaw. However, these trees are no longer ordinary wood: organic matter has given way, during their fossilization, to a structure mainly composed of quartz.
The trunks were buried in sediment more than two hundred million years ago. The lack of oxygen slowed their decomposition, while minerals penetrated their cellular structure and crystallized. Impurities, especially related to iron or manganese, explain some of their colors.
Quartz is hard, but brittle. When the layers that contained the trunks were subjected to constraints, they were able to break like glass sticks. The visible cuts do not show a logging: they show what happens to a tree when, becoming stone, it can no longer bend like wood.
What we know
Documented mineral processes and fractures; no instantaneous transformation.
To go to the source
References consulted on 3 October 2026. Linked pages may be in another language.
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