アメリカ内務省のインスタグラム(usinterior) - 9月17日 00時21分

Walking between the rolling clay hills at Petrified Forest National Park in #Arizona, you can stumble onto a scene that looks like a lumberjack went mad. But this wasn't the work of an axe or saw. Over 200 million years ago, fallen trees washed into an ancient river system and were buried quickly enough that oxygen was cut off and decay slowed. Minerals, absorbed into the porous wood over thousands of years, crystallized and replaced the organic material forming what we call petrified wood. The crystals are hard and brittle, fracturing easily when subjected to stress. Over time, the still buried petrified trees broke like glass rods -- giving the appearance today of logs cut with a chainsaw. Photo @PetrifiedForestNPS by Jacob Holgerson, #NationalPark Service. #PetrifiedForest #science #usinterior

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• PetrifiedForestNPS