During my exploration of Arizona, during December of 2010, I found myself on the Northeastern part of Arizona. I was only 2 hours east of Flagstaff, (on I 40), when I had the opportunity to drive through the Petrified Forest National Park.

The Petrified Forest National Park holds the largest and most beautifully preserved collection of petrified wood ever found. Here, the slow process of fossilization has turned large trees into solid stone.

Some 225 million years ago, these trees were part of an ancient forest, which was home to giant fish-eating amphibians, large reptiles, and early dinosaurs. After falling, the trees were washed downstream onto a flood plain at this location in northeast Arizona, and subsequently buried by silt and volcanic ash.

Imaged above, despite a raid burial, most of the trees would still have slowly decomposed if not for the volcanic ash in the above Chinle’s river mud. When the silica-charged water from the above ash, permeated the buired logs, chemical reactions with organic material caused the silica to precipitate out. Microscopic crystals of quartz called Chert solidified in all of the pore space of the trees’ cells, preserving the cell walls in a matrix of stone. This process is called permineralization. The trace elements of iron, manganese, and other elements in the ash, pigmented the Chert in a myriad shades of red, yellow, blue, purple, and black. Such varicolored Chert is known as Agate.

As mentioned above, many of these trees rotted away, but the ones that survived were transformed into the beautiful fossilized logs that I’m viewing in 2010. Dissolved silica from the volcanic ash slowly filled or replaced the cell walls, crystallizing the trees into mineral quartz.

Pictured above, the petrified process was often so precise that it preserved every detail of the log surface and, occasionally, the internal cell structures. Iron rich minerals combined with quartz during the petrification process, to give the trees a brilliant rainbow of colors.

Today, fossilized logs lie strewn across the clay hills and exposed in cliff faces, (pictured above).

Pictured above, the petrified trees are hard and brittle and break easily when they are subjected to stress.

The Petrified Forest also contains many fine examples of rock art which early people carved on the surfaces of boulders, canyon walls, and rock shelters, (picture above). The range of images is staggering; human forms, feet and handprints, birds, lizards, snakes, bats, coyotes, bear paws, bird tracks, cloven hooves, and cougars, (pictured below).

These petroglyphs may commemorated important events, mark clan boundaries, document natural events such as the summer solstice, and some may even be doodles.

The heavily-eroded badland hills of the Painted Desert have a multi-layered effect because their soil contains a kaleidoscope of red, orange, pink, blue, white, lavender and gray minerals. In the northern part of “The Petrified Forest National Park”, it’s a feast for the eyes, especially toward sunset when the colors shine at their most spectacular.

The Painted Desert is part of the Chinle Formation, which comprises soft sandstone sediments from the floor of an extinct water body dating back 225 million years. The rate at which the sediments were deposited determined the concentrations of iron and aluminum minerals in each layer–hence the colors. Slowly deposited soils turned red, orange, and pink, while rapidly deposited soil containing less oxygen created blue, gray, and lavender hues.

The Painted Desert, is an arid land, sparsely vegetated with flat topped mesas and buttes standing out from the hills. Pictured above, is a vantage point along the rim that gives a sweeping view of the December landscape of northern Petrified Forest National Park.