Arizona really had a lot to show us on this trip. Our last stop in this state was the Petrified Forest and Painted Dessert. Both can be seen in the same park although the painted dessert really stretches all the way back west to the grand canyon. The painted dessert was the name given to the land with these little foothills. Very pretty.
Of course, they come in monochrome too.
In the park is the remnants of a ancestral Puebloan people. Here is a summer solstice marker which marks the point when the days start to get shorter (usually June 20th in the Northern Hemisphere). They could tell when it was the solstice by looking at the shadow cast by another rock at about 9 am. If it pointed to the center of the spiral, they knew the days would start getting shorter.
Another group of petroglyphs; the meaning of which has been lost.
The petrified forest has a lot of wood laying around that has turned to stone. Now days they have strict laws that prohibit removing wood from the park but a lot of the best samples have been removed before the park was founded in 1906.
Petrified wood forms when wood is covered and hence isolated from oxygen. The lack of oxygen delays the decomposition process. The organic cells are then replaced with different types of minerals delivered by water trickling through them. Different minerals produce different colors. According to the pamphlet we got:
red/pink-Hematite, Fe2O3
yellow, brown, orange-goethite HFeO2 and Fe2O3
green-reduced iron, Fe
white-silica SiO2
black-carbon or pyrite (FeS2)
purple/blue-manganese dioxide MnO2
The bark looks especially real.
This is a picture of a petrified tree without any support underneath it. Concrete was placed underneath it in the early 1900s to prevent it from collapsing. Current park practices would have not allowed this.
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