Petrified Forest is a National Park where the largest concentration of petrified wood is found. Unlike Florissant where the stumps are found right where the trees were growing, these trees grew 225 million years ago in a vast forest on nearby mountains. They were washed away in a flood and buried in the bottom of a river. The silt that surrounded them gradually hardened into a rock. Then they slowly underwent a petrification process similar to the trees at Florissant. However, this wood is much more colorful than the wood at Florissant because in addition to silica, they contain minerals like iron and manganese that give them different hues.