Long Logs Trail, Petrified Forest NP, Arizona - Paleontology and Fossils on Waymarking.com

200 million years ago, this area was covered with a tropical forest. In seasonal flooding, trees were washed away from the forest and accumulated in sandy river channels, where they were later buried by layers of gravely sand, rich in volcanic ash from volcanoes further to the west. The silica in the volcanic ash permineralized the buried logs. Over a long periode of time, all the wood was replaced with silica, colored with oxides of iron and manganese. Much later yet, the desert wind blew the sand away, leaving only the heavy silica deposits.

And so, something like this (below, left), turned into something like this (below, right).

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While there are interesting things to see everywhere in the park, we think the best specimen can be found along the Long Logs Trail in the southern part of the park. Here are our favorite examples.