A rather small National Park is the Petrified Forest National Park close to the interstate I-40 between Flagstaff and Albuquerque, New Mexico. The attractions there are the petrified wood and the different colors of the surrounding desert. It's probably most interesting for geologists but also fascinating for rest of us to see the wood, but FEEL the stone. The Visitor Center has a nice exhibition which explains the creation of the petrified wood.
But don't expect to see any petrified forests as the name might suggest, it's simply a collection of pieces of petrified logs of those trees...

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