Petrified Forest National Park

4/4/19

The Petrified Forest is the largest deposit of the mineralized remains of Mesozoic forests. The petrified logs in the park are fossilized tropical conifer trees and are over 200 million years old. They formed when dead trees became buried by river sediments then were infiltrated by silica from volcanic ash mixed with the sediments which recrystallized to quartz and replaced the organic material. The brilliant colors in the logs came from minerals. Pure quartz is white or clear; manganese oxides form blue, purple black and brown; iron oxides form yellow, red, orange, and brown. The park is over 140,000 acres and the park road is 28 miles long

Examples of Petrified Wood

The petrified trees are found around the forest in small and large pieces. Often the logs look like someone cut them, why? About 60 million years ago, forces of geology started the uplift of the Colorado Plateau. This area went from deeply buried to being uncovered and raised more than one mile above sea level. As a high point it is continuously eroding away, exposing old rocks and their fossils (including petrified trees). So the movement and erosion of the land is what caused the logs to break. And the inner surfaces were they have broken are flat becasue quartz snaps across the logs shortest area across.

Puerco Pueblo was built by the ancestral Puebloan people who occupied the area A.D. 1250-1380.

The hunter gatherer sites, thousands of petroglyphs and hundreds of pictographs and ruins are found in the forest. Petroglyphs in the Petrified forest illustrate a 10,000 year continuum of human land use.

Can I pee on the Petrified Tree?

Lunch in the forest.

Painted Desert. The colorful bands in the Chinle Formation (Upper Triassic continental geologic formation) give the desert it's name, have coloration due to the presence of minerals. The red and green layers have equal parts iron and manganese. the difference in color depends on the ground water table when the soil was formed. The greenish/bluish hue is where the water table was high and caused a lack of oxygen in the sediments. the reddish soils were formed where the water table fluctuated allowing oxidation, aka rust.