Located in the Navajo and Apache counties of northwestern Arizona, the Petrified Forest National Park is characterized by large deposits of petrified wood. From small shards to massive fossilized trunks, they are the remnants of a prehistoric forest.
When a tree growing by the banks of a stream dies, it loses all its leaves, branches and bark. The river digs into the tree until the tree topples over and is carried downstream. Consequently, the tree gets stranded on a shore bank and gradually gets buried under sand and mud. This deep burial provides a seal around the bark against bacteria and oxygen. Instead the silica from the ground water seeping into the bark replaces organic matter with quartz crystals. Thus the log is now “petrified”. Here is a sample of petrified wood at the Petrified Forest National Park that has been polished.
The fossils excavated at the Petrified Forest National Park largely belong to the Late Triassic period, dating around 225 million years ago. The climate was tropical and there was abundant vegetation including ferns, horsetails, cycads and giant conifers. Early inhabitants included fish, clams, snails, crayfish, early reptiles and dinosaurs.
One example is a vertebrate fossil belonging to a phytosaur, an aquatic predator resembling modern day crocodiles. At a length of 4 feet, the below displayed phytosaur skull is the largest ever collected. This phytosaur may have measured 17 feet long and weighed around 2100 pounds.
In 1936, the University of California Berkeley reconstructed this Triassic landscape after a phytosaur skull was discovered with bite marks on its nose, possibly inflicted by another phytosaur.
The Blue Mesa drive at the Petrified Forest National Park covers 3.5 miles of variegated landscape. Shaped by wind and water, it is a hue of colors. Don’t forget to snap those photos!