The 93,533-acre Petrified Forest National Park contains an abundance of petrified logs. Most of the brilliantly colored trees are prone, and many are in fragments. The early dinosaurs once roamed the area, and numerous fossil bones and fossil plants have been discovered in the park. About 225 million years ago the trees grew in the highlands to the west and southwest of this once swampy section. Geologists currently believe that streams flowing into the basin from these highlands carried dead logs and buried them in sediments rich in volcanic ash. Silica slowly impregnated the logs until they became virtually solid stone. Iron oxide and other minerals stained the silica to produce rainbow colors. Later the region was uplifted and erosion exposed part of the logs; many remain buried to depths of 300 feet. There are five areas with heavy concentrations of pertrified wood in the park; Blue Mesa, Jasper Forest, Crystal Forest and Black Forest.
