I love that we visited this park around Halloween, because I always found the words “Petrified Wood” amusing. What’s it so scared of anyway? As it turns out, nothing. The trees all got stuck in a quagmire of silt and didn’t decompose because there was no oxygen. Then silica filled water leaked in and over time the biological components were replaced by stone. Okay, so that’s my very abridged and not-so-scientific version. If you would like to get a better story, go here: http://www.nps.gov/pefo/naturescience/index.htm
However, what is really amazing about this part, aside from the beautiful badlands and painted desert scenery, was the sheer number of pieces of petrified wood. They were large and small and in every direction and in all array of colors. Very cool stuff.