Near Holbrook, Arizona – March 25, 2022
Progressing east and west, Interstate 40 divides Petrified Forest National Park into northern and southern sections. The interstate generally follows the path of historic U.S. Route 66, which connected the midwestern United States to the country’s west coast in the first half of the 20th century. Although Route 66 stretched more than 2,200 miles from Chicago to Los Angeles, Petrified Forest is the only national park with former segments of the historic highway within its boundaries. The area south of the interstate, much larger in size than the northern part, contains most of the petrified wood specimens in the park. The northern area, however, boasts incredible roadside vistas of the Painted Desert and a sizable national wilderness area. Nancy and I visited the northern part of the park in late March. Gunther stayed with Rusty in the Goddard, but Nancy and I would enjoy the dog’s company when we returned to the park the following day.
We briefly stopped in at the northern visitor center, which was undergoing significant renovation at the time, then proceeded to drive along a route that included a number of overlooks of Petrified Forest National Park.
I decided to use my 14mm wide-angle lens for taking pictures the day we visited the Painted Desert. I got it a couple of years ago to primarily take pictures of the night sky but thought its properties would help capture the feeling of the vast open landscapes of Petrified Forest National Park. There is a disadvantage to using this lens, though: it’s not automatic, so the aperture, ISO, and other settings all must be set manually. I’m no good at any of that. Many of the photos I took were over- or under-exposed, and I had to make manual adjustments using a couple of pieces of photo editing software.
Petrified Forest National Park contains only a small part of the Painted Desert, which stretches across almost 8,000 square miles of northeastern Arizona. The colorful rocks, primarily mudstone and sandstone, of this region are called the Chinle Formation. Deposited from 227 to 205 million years ago during the Late Triassic Period while most of the land area on Earth was on the single supercontinent Pangaea, the rocks have been buried, lifted, and eroded during Pangaea’s breakup and shift into today’s major continents.
During the Late Triassic Period, the land comprising Arizona’s Petrified Forest National Park was located just north of the equator and supported a much different environment (different enough, for example, to support a forest of 180-foot-tall trees that would later become petrified). As Pangaea divided, the land mass migrated north and the land itself underwent massive changes.
The Chinle Formation is itself divided into five members: Mesa Redondo, Blue Mesa, Sonsela, Petrified Forest, and Owl Rock. Each member represents a transition of the land from wet to dry environments over millions of years: the Mesa Redondo, the oldest layer and therefore the one underlying the rest of the formation, consists of red sandstone originally laid down 226 million years ago, and the youngest, Owl Rock, includes pink and orange mudstone at the top of the formation that was deposited 207 million years ago.
Older rock formations in the Painted Desert are at the bottom of the geologic column, and the layers of rock grow younger in age as the elevation increases. The colors of these rocks come from the iron they contain. Drier climates allow the minerals to become exposed to oxygen, causing the iron to rust and develop distinctive red, brown, and orange colors. When the climate is wet, moisture essentially covers the sediments and prevents their oxidation. Those layers are colored blue, gray, and purple.
Nancy and I took a short hike along the rim of the basin, and one of the highlights of that walk was a stop at the Painted Desert Inn, which was originally built as a respite for travelers on Route 66. The highway passed just a short distance south of the building, and a spur road brought visitors to the inn for refreshments.
The interior of the Painted Desert Inn now serves as a visitor center for the Painted Desert as well as a museum with artifacts from the inn’s heyday. It’s all very impressive and you’re going to have to take my word on that because none of the pictures I took inside turned out.
Despite my photographic foibles, we really enjoyed this first visit to Petrified Forest National Park. I grew up on the eastern plains of Colorado, and I know long, uninterrupted distances. They are nothing compared to what can be seen in northeastern Arizona.
We’d see more of the park, and a little bit of actual fossilized wood, the next day. (Actually, we’d see a lot of fossilized wood. So. Much. Fossilized. Wood.)