By: Paul S. Cilwa Viewed: 12/16/2017
Occurred: 7/10/2017
Topics/Keywords: #Arizona #PaintedDesert #PetrifiedForestNationalPark #Travel #USA Page Views: 350
Keith, Michael, Ella, and my son John visit Petrified Forest National Park just to take pictures.

Today was 'Prime Day', based on the fact that the date—7/10/2017—as a number (1102017), is a prime number. Even if one leaves out the century from the date, 11017 is also prime. Plus, the full date is a palindrome, as it reads the same forwards and backwards.

On such an auspicious day, my son John suggested that we pile in his truck and head for Petrified Forest. John is currently sharing a house with my ex, Michael. So Keith, Ella (our dog) and I drove there in the morning, since their house in Mesa was actually along our way.

We took a 2-hour detour to drive through Snowflake, where Michael and I first moved to Arizona in 1997. It had certainly built up a bit in the past 2 decades. But we didn't go that way to take photos. We simply wanted to enter the Petrified Forest National Park from the south entrance, which I remembered being closer to Snowflake than Holbrook. (It is not.)

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Our route also took us through Payson and up the Mogollon Rim escarpment. At the top, we stopped to give Ella a chance to stretch all four of her legs, while John took his new camera to the cliff to get some photos.

Paul S. Cilwa
Paul S. Cilwa

Ella was very excited to have a chance to meet another dog.

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As I wandered with Ella off the path, I found a burnt tree trunk. Was it struck by lightning? Cut down and stump burned for some reason? I have no idea but I found it interesting.

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Continuing on AZ route 260, we ran into a monsoon rain that was expected. We passed beneath it quickly, but the associated dramatic skies would stay with us the remainder of the trip.

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At the "Museum" just outside the South Gate (it's really just a gift shop; the real Museum is in the Park), there was an example (selling for thousands of dollars) of the kind of minerals sometimes found within petrified wood and other rocks.

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The Rainbow Museum within the Park includes a number of interconnected paved paths that wander among the richest exposure of petrified wood in the park. In addition to the wood, there are also awesome sights to see.

Paul S. Cilwa
Paul S. Cilwa
Paul S. Cilwa

Keith and Ella enjoyed the breeze, which kept the 92deg;F heat from being unbearable.

In real life, Ella was on-leash, as is (I assume) required in the park. Besides, I don't really trust her not to wander off, especially if she sees another dog. However, the leash really spoils the photo. So I removed it digitally.

Paul S. Cilwa

Did you ever see a dog enjoy a breeze more?

Paul S. Cilwa

At the highest point we had quite the view of the gently rolling hills beyond. 220 million years ago, this was a great river delta, similar to the Amazon but much larger. (In fact, no larger present-day or ancient river deltas have yet been found.)

Paul S. Cilwa
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While Ella didn't seem to appreciate the scenery, she loved being with us.

Paul S. Cilwa

Petrified wood is a fossil. It forms when plant material is buried by sediment and protected from decay due to oxygen and organisms. Then, groundwater rich in dissolved solids flows through the sediment, replacing the original plant material with silica, calcite, pyrite, or another inorganic material such as opal. The result is a fossil of the original woody material that often exhibits preserved details of the bark, wood, and cellular structures.

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Some specimens of petrified wood are such accurate preservations that people do not realize they are fossils until they pick them up and are shocked by their weight. These specimens with near-perfect preservation are unusual; however, specimens that exhibit clearly recognizable bark and woody structures are very common.

Paul S. Cilwa

In 1961, my family visited Arizona for the first time; and our trip included Petrified Forest National Park. Below we see my sister, Mary Joan, and my mom examing petrified wood at or near this very spot.

My mom was the most devout Catholic who ever lived. But she couldn't resist swiping a small piece and lying to the guard at the gate, who asked whether we'd taken anything. And, of course, she felt guilty about it the rest of her life.

Centuries of scouring flood waters washed out the arroyo, or gully, beneath this 110-foot petrified log to form Agate Bridge. The stone log, harder than the sandstone around it, resisted erosion and remained suspended as the softer rock beneath it washed away.

Conservationists felt this ages-old natural bridge needed architectural support and in 1911 erected masonry pillars beneath the log. In 1917 the present concrete span replaced the masonry work.

Current National Park Service philosophy allows the natural forces that create unusual features to continue. If discovered today, Agate Bridge would be left in its natural state. Eventually, the natural forces that created Agate Bridge will cause it to fall with or without its supports.

Paul S. Cilwa

In 1961, it was not forbidden to leave the paved path and climb down into the gulley, where this photo of Agate Bridge was taken.

I found the geology in the vicinity of Agate Bridge to be equally riveting.

Paul S. Cilwa
Paul S. Cilwa

As we continued North on the Park road, we hit our first stretch of Painted Desert beneath the lowering skies.

Paul S. Cilwa

The Park is home to many ravens, which traditionally are the "guardians of sacred places". They also help out by eating scraps of food dropped by careless tourists.

Paul S Cilwa
Paul S. Cilwa
Paul S. Cilwa
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Finally, north of I-40, the northernmost section of the Park provies scenic views of the most spectacular sections of the Painted Desert, which stretches from the eastern end of Grand Canyon National Park and Petrified Forest National Park.

Paul S. Cilwa

The Chinle Formation that makes up the "Painted Desert" was deposited over 200 million years ago during the Late Triassic Period. The colorful badland hills, flat-topped mesas, and sculptured buttes of the Painted Desert are primarily made up of the Chinle Formation, mainly fluvial (river related) deposits.

Paul S. Cilwa

The colorful layers in the Chinle Formation represent ancient soil horizons. The coloration is due to the presence of various minerals. While the red and green layers generally contain the same amount of iron and manganese, differences in color depend on the position of the groundwater table when the ancient soils were formed. In soils where the water table was high, a reducing environment existed due to a lack of oxygen in the sediments, giving the iron minerals in the soil a greenish or bluish hue. The reddish soils were formed where the water table fluctuated, allowing the iron minerals to oxidize (rust).

Paul S. Cilwa

Where the Bidahochi and Chinle Formations make contact is an unconformity. An unconformity represents missing rock layers which in turn represents missing time. The missing layers were eroded away during the period this area was underwater. It's like a geology textbook with missing pages. You can tell that a page is missing but you can't tell what was on them. The Chinle Formation was deposited over 200 million years ago but the Bidahochi Formation is only about 8 million years ago. The contact between the Bidahochi and Chinle Formations represents 192 million years of missing time!

Paul S. Cilwa

As we were about to leave, Ella startled a group of ravens who then hovered in the wind just a few feet above us, out of our (and, especially, Ella's) reach.

Paul S. Cilwa
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With the rain about to hit, we decided to bolt for the car. But not until John took a final photo of Ella, who wasn't nearly as concerned over being caught in the rain as we. (Arizona people love rain but seldom dance in it.)

John D Cilwa

Having already gotten a look at Snowflake, we took a more direct (and shorter by 2 hours) route back home. At John and Michael's, Keith, Ella and I transferred back into our own car and made it home 13 joyful hours after having left.

It has been, in fact, a very prime day.