Hike Back in Time at Petrified Forest National Park

Scenery while hiking cross-country through the Flattops.

For me, trying to understand geological time is a bit like trying to fit a square peg into a round hole. It takes some serious reshaping before the pieces start to fall into place.

When I met up with Dorenda and Matt Walters, my hiking guides at Petrified Forest National Park, little did I know, just how much mental craftwork I was in forโ€”225 million yearsโ€™ worth! That is how much life history exists in the parkโ€”a seriously mind-boggling sum.

A Long, Long, Long Time Ago

Before setting out on our hike, Dorenda and Matt Walters arranged for a tour of the parkโ€™s museum collections. Matt Smith, curator and paleontologist, led us on this venture. 

To start, Matt Smith shared a โ€œmental-gymnasticโ€ he uses to try and get his mind around the 225-million-year history:

“T. rex died 66 million years ago,โ€ he explained. โ€œHis oldest cousin lived during the Triassic in (what is now) the Petrified Forest 220-225 million years ago. We are looking at more time between T. rex and the oldest dinosaur and T. rex and us. T. rex is closer to the iPad than its earliest ancestor.โ€

This is the timeframe we are working withโ€”almost four times the amount of time it takes to go from dinosaurs to humans. So, as you can imagine, back then, the Earth was a completely different place.

โ€œThis planet was on the other side of the galaxy,โ€ described Matt Smith. The continents were united into one supercontinentโ€”Pangea.  It was the dawn of the dinosaurs. Mammals were just getting started. And flowering plants had not even shown up yet. 

In other words, it was a long, long, long time ago.  

The Box

After his brief introduction to time, Matt Smith led us into the Museum Demonstration Lab, or “the box,” as he called itโ€”a small white room with windows and desks facing outside that allows visitors to glimpse in the โ€œbehind the scenes workโ€ paleontologists do at Petrified Forest. 

โ€œFossils are our jam,โ€ said Matt Smith, before introducing us to the roomโ€™s current occupantsโ€”a metoposaur skull and a phytosaur skull. Each sat on separate desks facing the window, cradled inside their plaster jackets.

Metoposaur

The metoposaurโ€™s fossil skull was roughly triangular and flat or, as Matt Smith put it, โ€œshaped like a toilet seat.โ€

Overall, metoposaurs were large amphibians, โ€œup to 10 feetโ€ in length, with rough textured skin similar to the bone underneath, and a body plan like a modern-day crocodile, only stouter.

As carnivorous feeders, metoposaurs would sit on river bottoms, โ€œopen up their mouths like a bass and feed off whatever came into their mouth,โ€ said Matt Smith.

He pointed to a deeper trench hidden in the texturing of the fossil. He explained how this trench was part of a lateral line system, like fish have. This system would have allowed metoposaurs to sense their prey, even in the murkiest of waters by detecting changes in pressure or electrical pulses.

Metoposaurs were โ€œcommon everywhere up until the end of the Triassic,โ€ said Matt Smith

Matt Smith standing next to the metoposaur skull in “the box.”

Phytosaur

The phytosaur skull had an even more unusual shape. It looked a bit like an alligator but with a very long snout, and nostrils toward the back of the head, instead of the front.

Phytosaurs were huge, maybe โ€œ25-30 feet long,โ€ with long tails and sharp teeth; again, with the body plan of a crocodile. โ€œThey were fish eating specialists,โ€ said Matt Smith, โ€œCrocodile-like 80 million years before crocs.โ€

He went on, โ€œThey donโ€™t have common ancestry (with crocodiles) โ€ฆ these guys turned โ€˜crocodileโ€™ by stretching out their premaxilla.โ€ Crocodiles, on the other hand, stretch out everything in the snout. That is why a phytosaur has nostrils at the back of the head and crocodiles the front.

Crocodiles and phytosaurs are an example of convergent evolutionโ€”similar environments, resulting in similar structures on totally separate locations and timelines.  When a body plan works, it works!

The phytosaurs are one of several archosaurs that are found at Petrified Forest. Phytosaurs are not dinosaurs and exist on a separate branch of the archosaur family tree. They are a group of reptiles that includes dinosaurs as well as modern birds and crocodiles. Phytosaurs are one of many Triassic archosaurs found in the park. The only two living archosaur groups are crocodilians and birds.

Matt Smith with the phytosaur skull in “the box.”

A Curved Femur

After our visit to โ€œthe box,โ€ Matt Smith brought us into the collection rooms. Lined with metal cabinets, the collection room contains hundreds of catalogued artifacts and specimens found in the park.

The first set of specimens Matt Smith introduced us to were fossils from an azendohsaurid reptile.

โ€œThis animal wasnโ€™t known in North America,โ€ Matt Smith explained, until 2014 when a weird vertebra, discovered in a loan return, piqued the interest of park staff. Before long, a fossil site filled with azendohsaur fossils was discovered, and 40 different field jackets with specimens were collected.

Now, all these specimens stood in front of usโ€”organized and packed into a short metal cabinet with wheels.  Matt Smith pulled open the first drawer. Dozens of tiny femora (upper leg bones), broken from the weight of time, lay arranged in small, labeled boxes.

Matt Smith pointed to one of these fossils with a slight bend in it. โ€œThis curve is due to natural disease like rickets,โ€ he remarked.

Other drawers contained other parts. All put together,the azendohsaur was about the size of a medium dog โ€œwith a long neck and sprawling leg posture,โ€ described Matt Smith.

Azendohsaurid reptile fossils in a drawer.
The curved femur.

Modern Dinosaurs

Next Matt Smith directed our attention to a much larger metal cabinet. โ€œBirds. We have a lot of birds,โ€ he exclaimed as he opened the cabinet and pulled out a drawer. And there they were lined up in a rowโ€”dozens of taxidermy birds, from the Northern Flicker to Common Ravens. Matt Smith picked up one of the specimens, a Saw-whet owlโ€”a bird never-before-seen at the park. That is until it was found recently on park grounds, having died of unknown causes.

Now you might be wondering, โ€œwhy save a bunch of dead birds anyway?โ€

Well, museum collections are like information investment accounts. The value of the specimens when first catalogued might seem small, but over time, with changes in technology and new scientific questions, a greater value is realized.

As Matt Smith put it, pointing to the tray of birds, โ€œHopefully, these will help answer questions in the future.โ€

In addition to modern-day bird specimens, a 220-million-year-old dinosaur fossil was found in the parkโ€”the ancestor to modern-day birds. โ€œWe have had dinosaurs here longer than anywhere else in North America,โ€ Matt Smith stated. โ€œAnd we have proof.โ€

Drawer of varied bird specimens.

People

Closing the bird specimen cabinet, Matt Smith directed us to another similar non-descript case.

Inside was a collection of pottery arranged carefully on pull out trays.  The vessels were a variety of shapes and colors, each one carefully decorated.

โ€œPeople have also been walking around the forest for a long time,โ€ said Matt Smiht. Though not as staggering as the dynasty of archosaur life, human history in the park goes back 13,000 years. 

And they are still around today. There are “37 tribes on the land,” he states, referring to the number of tribes that are affiliated with the parklands.

Among the artifacts in the collection were examples of Adamana Brown-style pottery, a form of pottery dating back to around 250 BCE. These early brown and gray ceramic pieces date back to a time when pit house villages sprung up and seasonal farming was a focus.

Later, from 650-950 CE the ceramics changed from plain brown and gray to decorative black-on-white designs and corrugated pieces, a style associated with pueblo development. Then from 950 to 1300 CE ceramics diversified even more, with black-on-red and polychrome examples showing up in the Petrified Forest archeological records.

Many of these forms stood on attention against the stark gray industrial cabinetry.

Drawer of varied pottery.

A Legacy

Matt Smith pointed out a piece that was yellow and brownโ€”a Hopi-style ceramic.  โ€œThis one is probably 400 to 500 years old,โ€ He said, โ€œfired at a slightly higher temperature,โ€ than the black and white pieces.

He went on to explain how this style of pottery was almost completely lost. He pointed to another piece from the 1960s by Fannie Nampeyoโ€”โ€œthe last one who knew how to pot in this style.โ€ Fanny Nampeyo learned from her mother before her, also called Nampeyo, who revitalized the ancient Hopi style in the 1890s. Without the Nampeyo legacy it is possible the Hopi pottery tradition would have been lost.

Turkey Feet or Lung Fish

Before Matt Smith shut the cabinet, a small piece of corrugated pottery caught my eye. Decorated with simple lines that resembled chicken feet, I asked Matt Smith to tell me more about it.

โ€œThis is cool to me,โ€ enthused Matt Smith referring to the markings. โ€œOne archeologist thought they were turkey feetโ€ he said, but the number of talons does not add up.

โ€œIt is not a common design element,โ€ Matt Smith said, while he doubled back to another cabinet behind us and began rummaging around, so โ€œI have my own theory.โ€ He pulled out a small fossil that looked a bit like webbed feetโ€” โ€œlungfish teeth,โ€ Matt Smith exclaimed. He went onto explain how lungfish teeth are common Triassic fossils found in the park and have often been found associated with prehistoric structures.

Could these mystery markings be paying homage to lungfish teeth fossils? We just donโ€™t know.  

Lungfish teeth fossils.

Type Cabinet

We had been at it about 30 minutes, when Matt Smith took us to the creme de la crรจme of the museum collectionโ€””the type cabinet.โ€

โ€œIn natural science, you have got holotypes, explained Matt Smith. โ€œThey are the sampleโ€”skin, skeleton, genetic material, fossilโ€”that was used to describe a new species. They are the archetype of that animal.โ€ Every other specimen found must be measured against existing holotypes in order to determine if a species is new or not.

Holotypes

Matt Smith showed us a few of the holotypes housed in their museum collections. โ€œsome are pretty miserable, said Matt Smith, โ€œa single tooth or clawโ€ might define an entire species. One holotype that Matt showed us was Vancleavea campi, a species of reptile that may have lived more than 11 million years during the Triassic. โ€œCovered with armorโ€ฆ it isnโ€™t related to anything alive todayโ€ฆโ€ said Matt Smithโ€”it was essentially โ€œbulletproof.โ€

Of course, the challenge with modern-day holotypes is often ethically obtaining a specimen in the first place, especially when the species is rare. To get around this, people often must be creative and very patient. For example, Matt Smith told me about how scientists found a new species of iguana on the Galapagos Islands about 10 years ago. In order to obtain the holotype, they had to find a living iguana that they felt would work, put an RFID chip in it, and sit back and wait for nature to take its course. I believe they are still waiting to this day.

A drawer of holotypes, including Vancleavea campi.

Mussels

Matt Smith also showed us a diversity of Triassic freshwater mussels holotypes. Modern freshwater mussels are โ€œmore diverse than anywhere else in the world in North America,โ€ said Matt Smith. But they are in trouble. โ€œThese are going extinct faster than any other group of animals in the U.S.,โ€ Matt Smith explained, despite the fact that they are โ€œevil geniusesโ€ according to Matt Smith, able to disperse their young by smuggling a ride on migrating fish.

Collection of mussel holotypes

Plants

Matt Smith also showed us some plant fossils, among them fossil trees. There are โ€œ14 species of trees in the park,โ€ according to Matt Smith. However, despite their abundance working with plant fossils is difficult. โ€œPlants never die in one placeโ€ฆ they die in parts,โ€ said Matt Smith. You arenโ€™t going to find a complete plant body like you might for an animal. Thus, a plant holotype requires some closer examination. The tree holotypes Matt Smith showed us during our tour were thin sectioned specimens, in order to see the grain of the wood.

The type cabinet looked pretty similar to others we had seen with the exception that it was on wheels. Why? In the case of an emergency, wheels provide a quick getaway. โ€œ77 species would be lost if we didnโ€™t have this,โ€ stated Matt Smith.

Drawer of plant holotypes.

Whatโ€™s the Point?

And on that note, Matt Smith took us around the corner to the back of the collection room we were in. We walked past some furniture built by the CCC (Civilian Conservation Corps) in the 1930sโ€”another layer of human history at the parkโ€”and over to a final cabinet filled with artifacts.

The final cabinet we visited that day was filled with small clear packages of artifacts, each filed in equally small boxes. Shells from the Gulf of Mexico, pipestone from Wyoming, obsidian from Flagstaff, turquoise from New Mexico and, of course, petrified woodโ€”each artifact shaped by human hands– telling the story of human migration and technological change in the area.

Matt Smith pulled out several points and talked about their various uses. Like the pottery, Petrified Forest National Park hold a record of points/tools dating back 13,000 years from โ€œClovis through Folsom, basket maker, and Puebloan.โ€

Matt Smith described a place in the park, a playa, where some points and a lot of chunks of material (lithic scatter) have been found. โ€œThere are petrified wood depositsโ€ฆ and a little rise,โ€ said Matt Smith.  The playa would have been filled with water 13,000 years ago, so it would have been the perfect place to both hunt and make points for hunting.

One of many points Matt Smith showed the group.

The Lab

The final stop on our whirl-wind tour was the paleontology lab, so we stepped outside and made our way across the park campus. Before long, Matt Smith ushered us into another non-descript building.

โ€œSo, this is the Prep Lab,โ€ Matt Smith exclaimed. โ€œMost of what we do in here is paleontologyโ€ฆ we do basic conservation work for non-paleontological stuffโ€ฆ but we do the whole shebang for fossils–from the grave to the cradle.โ€

Gumby and Reynaldo

Looking around the room, it looked a lot like any other well-lit lab space, but with a couple rather large fossils sitting out in their plaster casts on lab benches.

 โ€œThis is Gumby, a phytosaur skull,โ€ said Matt Smith. The fossil was in disrepairโ€”the back end of Gumby lay in a plaster jacket in two pieces. Apparently, Gumby got its name because it is bendy, but also likes to break; so, after two or three breaks, the staff decided to create a mold of it. Matt Smith told me that the plan is to use casts from Gumby and several other individuals to create a replica of a phytosaur skull for display. He showed me a partial cast of a phytosaur jaw made from two fossils cobbled together.

Matt with a cast of a phytosaur fossil.

โ€œAnd here is Reynaldo,โ€ said Matt Smith, โ€œheโ€™s a big sexy beast.โ€ Collected in 2016, Reynaldo has been an on again off again project for several years nowโ€” โ€œprobably three or four hundred hoursโ€ put into preparing the fossil, said Matt Smith but now โ€œit is really close.โ€ With a little more reconstruction of the faceโ€”and lots of glue and plasticโ€”the staff hopes to get him stabilized soon.

The reconstruction of Reynaldo.

The Small Stuff

As Matt Smith grumbled a bit about the frustrating nature of larger pieces like Reynaldo and Gumby, he directed the group toward the back corner and another shiny metal cabinet.

โ€œMy heart lies more with stuff like this,โ€ said Matt Smith as he pulled out a drawer and pulled out a small vial with a tiny fossil inside. โ€œAll these tiny little fossils to me are a lot more fascinatingโ€ฆ

I can prep them out in a day or two, and I can store a lot of them, and itโ€™s just way more rewarding if you ask me,โ€ he explained.

A drawer of small fossils.

Origin of Lizards

In order to study the small fossils, they are sent to another lab for a Micro-CT. This sort of imaging is like a regular CT scan, only more intense and the scan machine is much smaller, fitting on a desktop. The Micro-CT can get finer detail with micron-size slices of images captured. The information from the Micro-CT can then be used to print a blown-up plastic version of the fossil using a 3D printer.

Matt Smith held up an example of a 3D printed jaw of a reptile that had been enlarged from just 1 cm long to at least 10x its original size.

Matt Smith pointed to a ridge running along the skull. โ€œYou can see things like the tunnel running through thereโ€ฆโ€ he said. This type of detail is brought out through the printing process.

It also turns out the 3D printed jaw that Matt Smith was holding was from a Tuatara. Now found only in New Zealand, these creatures were common during the Triassic and beyond. They are like lizards, but with less flexible jaws and fused teeth that allow them to chomp down on and chew their prey. 

Finding Triassic Tuatara-like fossils in the park provides a useful link to the origins of lizards. โ€œLizards replace them,โ€ explained Matt Smith, โ€œIt was like this ecological arms race.โ€ Two reptile groups pitted against each other for survival. 

When you walk through the park today, all you see are lizards, but โ€œthey are here now because of this struggle that occurred 220 million years ago,โ€ said Matt Smith.

And with that, Matt Smith shooed us out to enjoy the rest of our day. We were just getting started.

3D print of Tuatara jaw.

Heading Back in Time

With my brain crammed full of information, it was finally time to head out into the park. We said our goodbyes to Matt Smith the paleontologist, and Dorenda, Matt Walters, and I, hopped in our cars to begin the 28-mile drive through Petrified National Forest Park.

Heading south, we drove past the Painted Desert and pulled off for a quick stop at the Blue Mesa Member of the Park to look at some petrified wood.

โ€œThe youngest part is 209 million year ago, up where we first started,โ€ explained Dorenda, โ€œin the Painted Desert with the red badlands.โ€ 

Now we were looking out at 217-million-year-old badlands of greys, blues, and greens. With puffy white clouds dancing across the otherwise expansive bright blue sky and casting shadows, the view was breathtaking. 

The view over the Blue Mesa badlands.

Keystone Arch

Hidden amongst the bentonite clay hills, were petrified logs of various sizes and shapeโ€”each also uniquely colored.

โ€œThe theme of this park is erosion, erosion, erosion,โ€ said Dorenda, as Matt Walters led us out into the colorful environment. It is through the action of water and wind that the petrified logs that the park is famous for are revealed over time. 

Matt and Dorenda stopped in front of one of these logs that arched its way from one side of a small gully to another.

โ€œThis is a really special petrified log,โ€ explained Dorenda, โ€œthis one is called Keystone Arch.โ€ Aptly namedโ€”the single log was several piecesโ€”held together by touch points between each piece. It was beautiful, but temporary structure. The process of erosion, already acting day-by-day to bring the arch down.

Keystone Arch.

Distinct Species

I asked Dorenda and Matt Walters if they knew what species of tree Keystone Arch was made from. They told me there was no way of knowing without looking at the cellular structure. Most of the tree species, with a few exceptions, are too difficult to identify without this level of detail. โ€œThere were over 1,000 species,โ€ explained Dorenda.

Of course, some are more commonly found in certain locations. The north end of the park is called โ€œthe Black Forest,โ€ for example, and the petrified wood there tends to be darker in color because of differences in fossilization.

โ€œIt is just like forests today,โ€ said Matt, โ€œdifferent trees in different areas.โ€

Petrification

Scattered around the base of Keystone Arch were several pieces of petrified wood of various sizes and colors. This, of course, begs the question: โ€œWhy is there so much petrified wood in the park?โ€

Dorenda explained that during the Triassic Period the Petrified Forest would have been on a large supercontinent called Pangea, very tropical, and very wetโ€”with many freshwater streams, swamps, and lakesโ€”and of course lots of trees, some over 200 feet tall.

This combination of trees and water meant that many trees after death were toppled, as streams undercut their banks. These dead trees, often stripped of branches and bark, might then be transported downstream, collect in areas where water slows, and become buried in sediments where decay is inhibited.

โ€œThis area would have been a converging of waterways, and just a big damming of logs,โ€ explained Dorenda.

A piece of colorful petrified wood found near keystone arch.

Colored Stone

Blues, reds, oranges, yellows, purples, and blacksโ€”a palette of colors can be seen in each petrified log. The colors develop in the log next in the petrification process as mineral-rich groundwater travels through the logs. 

The petrified wood is mostly quartz minerals or silicon dioxide. For this reason, โ€œyou need silica for petrification,โ€ said Dorenda. In other words, you need volcanic material.  Since there is not much of a history of volcanism in the area, much of the material was blown in from the west during the Triassic.

โ€œSilica adheres to organic cells,โ€ Dorenda went on, so as the silica-rich water percolates down into the earth and reaches a buried log, it enters the wood and stops. The silica alters the wood into opal, replicating its features, and eventually transforming the wood into crystalline quartz over millions of years. 

And the colors? โ€œAs the silica solution goes through the earth it picks up minerals,โ€ Dorenda explained. Pure quartz is colorless. It is minerals like iron oxide or manganese that are responsible for the kaleidoscope of colors present in the stone.  According to Dorenda, iron oxides can create colors from yellow to red, even purple depending on the level of oxidation. Manganese creates dark woods from purple to jet black.

Some of the logs found in the Petrified Forest look a lot more like wood than stone. These logs, Dorenda explained, would have started to decay early on–creating inorganic cells that the silica dioxide wonโ€™t adhere toโ€”resulting in weaker, lighter permineralized logs. 

Matt and Dorenda had me hold a piece of each type of log in my hands so I could feel the difference in weight. Both felt heavy like stone, but the agatized stone was a bit heavier. โ€œOne cubic foot of agatized wood weights 160 lbs,โ€ said Matt.

At this point, Dorenda, Matt, and I navigated our way through the badlands and back to our cars to continue our journey through geological time.

Pieces of permineralized wood scattered on the ground.

The Flattops

I followed Matt and Dorenda further south into the park, before reaching a small pullout adjacent to โ€œThe Flattops.โ€ Here we met up with fossil preparator and paleontologist, Diana Boudreau, for the main eventโ€”a hike into the badlands.

After some quick hellos and grabbing our gear, we got moving right away.

I looked out onto the unmarked terrain. Like our earlier stop, there were flat topped mesas and rolling hillsโ€”only this time in shades of grey and red brown. Despite the similar feel of an alien landscape, this section of the park marks a different time frame from our early stop at Blue Mesaโ€”moving us forward in time to about 213 million years ago.

โ€œThe Blue Mesa region is mostly composed of the Sonsela Member. Here, we see the Flattops Beds of the Petrified Forest Member sitting just on top of Sonsela,โ€ remarked Diana as we descended from the road into the backcountry.

“The Flattops,” as seen from the road.

Older than Dinosaurs

Making our way cross-country, with Matt in the lead, I asked Diana to tell me more about the parkโ€™s geology.

โ€œSo, the whole park is Late Triassic in age,โ€ Diana began, and represents a range of time from 208 to 228 million years. โ€œThat is most of what is exposed here.โ€

Most of the fossils found in the park are not dinosaurโ€”a common misconception–she added. Instead, they are from a much older, larger group of reptiles called archosaurs. Distinguishable by differences in ankle and hip bones, archosaurs are the Triassic ancestors of many later lineages, including birds, crocodiles, and dinosaurs.

Geological Members

With the main fossil bearing members including the Blue Mesa, Sonsela, and Petrified Forest members, Diana continued.  Each member is distinct from the others based on certain traits, like depositional environment. 

โ€œWe will be crisscrossing between Sonsela and Petrified Forest,โ€ Diana remarkedโ€”moving between 216-million-year-old deposits of cross-bedded sandstone and 213-million-year-old mudstones and sandstones. Our footsteps dancing back and forth through time.

Cryptobiotic Soils

Matt set the pace, while Dorenda, Diana, and I followed closely behind. Watching our footsteps along the way. One of the first lessons for backcountry travel is to watch your step. Not only are there hazards to look out for, but crypotobiotic soils to protect.

A cryptobiotic soil is a dark soil crust that is formed by a suite of organisms, like fungi, lichen, bacteria, and algae, over long periods of time. These organisms are โ€œthe first biologic that grows in a sandy, arid environment,โ€ explained Dorenda and they build up the soil in such a way that it benefits plant life and prevents soil erosion.

However, one misstep and 50 years of microbial work can be completely dismantled. Dorenda and Matt pointed out some cryptobiotic soil growing near a plant. It looked a bit like moss growing on a rock, but darker.

All the wiser, we side stepped the growing mat and continued on our way.

Cryptobiotic soil found on the hike.

Human โ€œFootprintsโ€

As we hiked, our footprints marked our path across the desertโ€”a path that would later be washed away with the next rainfall. However, these were not the only signs of human presence during our walk.

Not too long after finding the cryptobiotic soil, we passed by a couple of pottery sherds โ€”archeological artifacts of human habitation hundreds of years oldโ€”the first of many.

One of the first pottery sherds we passed during our hike.

A while later, we came across a surveying โ€œbenchmarkโ€โ€”a point of reference for mapping. The date on the patinated copper surface read 1921โ€”100 years prior to our hike across the desert; placed by the U.S. General Land Office Survey before USGS existed. One-hundred years ago the park was newly established and the first phytosaur fossil found in the area was being described. 

These were early human โ€œfootprintsโ€โ€”impressions of a past that exists in clues and signs.

A survey marker, or benchmark from 1921.

Geology

For Diana, Matt, Dorenda, and I time passed quicklyโ€”both literally and figurativelyโ€”as we walked over the undulating hills.

At one point, Diana stopped abruptly. โ€œThis is a nice vantage point to talk about the geology here,โ€ she remarked.

Looking out to our left was a steep, eroding cliffside with horizontal bands of varying shades of brown. Diana directed our attention toward these bands. โ€œThis view shows a lot of the different flattops beds,โ€ she said pointing.

Diana then went on to describe each layer as a numbered unit starting with a section of sandstone at the top, followed by alternating layers of mudstone and sandstone. She explained how each deposit would have been laid down by a braided stream systemโ€”with sandy material deposited in the stream bed and more silty/muddy material along the banks.

The units we were looking at represented a time spanning about 1 million years from 213 to 212 million-years-ago. Starting with Petrified Forest Member Flattops beds at the top and the more rounded Sonsela Member at the base of the cliff. Each layer was thick, indicating a water rich environment over the 1 million years, but would have differed in the type of watery environment and the organisms that lived in that place at the time.

Diana pointing out the geological units.

Petrified Peat

As we continued hiking atop the Sonsela hills, Diana and I chatted, while Matt and Diana led the way, eventually stopping near what looked to me like a short fence made of solid rockโ€”a line of stone stuck out of the ground vertically. 

โ€œThis area here is what we called silcrete,โ€ said Dorenda. โ€œRemember when we talked about the petrified wood and we talked about those giant logs? And how as the water took its toll the branches and bark and everything would be gone?โ€ she asked me.

Well, according to Dorenda, silcrete is the result. Waterways collect all the partially decomposed wood bits in one place where they undergo the same process as the logs and are petrified.  โ€œIt is kind of like petrified peat,โ€ Dorenda stated.

Standing on End  

Of course, usually, silcrete is laid down in horizontal layers. The silcrete here was vertical. Making the spot a bit of a geological mystery, as there is no sign of faulting that might normally turn rock on end. 

โ€œIt is theorized that there was some sort of pressure that pushed it up through the sandstone, filling in the gaps,โ€ Dorenda told us.

โ€œYou will find silcrete through the whole park,โ€ said Matt, but vertical layers like this โ€œcan only be found in two places.โ€

Petrified peat, or silcrete, creating a vertical “fence.”

Wandering the Wilderness

After ample time spent taking pictures of the silcrete anomaly, the four of us continued our hike under blue, cloud-spotted skies.

With Matt Leading the way, Dorenda, Diana and I hung back and discussed a variety of topics from career choices to canyoneering, before the conversation shifted to the preservation of natural and ecological resources.

The Petrified Forest National Park was one of the first National Parks to have land set aside as designated wilderness in 1970. Wilderness is the highest form of protection public lands receiveโ€”restricting access to those on foot and limiting human impact. 

However, the Petrified Forest is unique in that it offers hikers and backpackers the opportunity to explore outside of a designated trail. In fact, it is encouraged, as there are no major trail systems in the park.

Of course, โ€œleave no traceโ€ principles still apply and often require extra consideration, especially in a place like Petrified Forest where archaeological artifacts and fossils are abundant. Even taking pictures requires special consideration to preserve the location of unique places that might draw crowds that may end up impacting the park negatively. Dorenda and Diana both expressed concerns about protecting artifacts and other special place locations. โ€œItโ€™s a weird line,โ€ said Dorenda, but an important one, not only for the resources being protected but often the safety of visitors to public lands as well.

Matt leading the way, leaving nothing but footprints.

An Eye

By this time, we were at least a couple of miles into the wilderness and the road where we started was a distant memory. Lost in the vastness of the wilderness (but not really lost thanks to our guide Matt), I asked Dorenda and Matt if they had any advice for those visiting the park, or any other natural place, for the first time.

Dorenda spoke first. โ€œTake the time to see the micro and macro view,โ€ she said. โ€œDo a 360,โ€ she suggested. She told me that she tends to keep her eyes to the ground. It takes deliberate effort to stop and look around.  But taking in both views will help you better appreciate all aspects of the park.

In addition, โ€œI think you develop an eye for things,โ€ she went on. Whatever you are looking for, whether it’s fossils, petroglyphs, or something else, if you learn what to look for you get better at finding it. Look for contrasts, different colors, textures, and size and that will help you

A Guide

Matt had a different take. โ€œIt is all being passed down,โ€ responded Matt. Learning about a place from others that know a lot more than you do can really help enrich your experience. 

โ€œWe had two mentors. They taught us a ton because they had to teach us the hikes,โ€ he continued.  โ€œWe were like kids in a candy store because we were learning so much.โ€

Taking it further, Matt recommends sharing what you learn. โ€œThe key this for us is to pass it onto people,โ€ he remarked.

Having spent more than half the day with Dorenda and Matt, I was able to see this key in action. And let me tell you, they are well practiced.

Candy store, Matt? More like Wonkaโ€™s Chocolate Factory!

Matt and Dorenda Walters leading the way.

Finding Fossils

One thing to know about Matt, is that when he slows down on a hike, it is time to look around.

It was getting near lunch time, and we had picked up the pace in an effort to make it to a lunch spot Matt and Dorenda suggested, so when Matt stopped abruptly, we knew there must be something interesting nearby.

Diana spotted it right awayโ€”a fossil! Laying on the dry desert floor was a small fossil of a bone, about the size and length of a snickers bar. It had a crackled texture and was broken in one place.

โ€œI think it is a phytosaur rib,โ€ said Matt.

Diana looked closely and agreed that โ€œit was the right size for a phytosaur.โ€ Definitely a long boneโ€”either โ€œa process from the vertebra or could be a rib,โ€ she said.

She picked it up and we looked closely at the fossil, pointing out the cellular structure visible in fossil bones before laying it back down.

I tried to imagine a large reptile sitting in a swamp waiting for its prey, but it only made me think of my own lunch waiting ahead of me.

A long bone fossil found during the hike.

Keep Looking

Continuing along we saw several more artifacts laying on the desert floorโ€”including a piece of a corrugated pot and another fragment of a vessel with a small hole in it.

Before long we had reached our lunch site, but we werenโ€™t โ€œallowedโ€ to eat just yet. Matt said that I would need to โ€œearn my keep first,โ€ as there was another artifact nearby and it was my job to spot it.

After several painful minutes of trying to spot what I thought would be pottery or a fossil, Matt guided my eyes to a faint figure inscribed onto a dark colored rockโ€”a rock I had been staring at for a good three minutes, at least.

Petroglyphs

The petroglyph in front of me was the impression of an animal of some sortโ€”carved into the dark desert varnish growing on a rock.  The image was fadedโ€”the result of time passedโ€”as the bacterial growth responsible for the varnish was starting to repopulate the etched-out areas.

โ€œThese are probably over 1000 years old,โ€ said Matt regarding the petroglyph.

Looking closely at the rock you could see small dimples formed the petroglyph impression. Matt explained that the petroglyphs would have been chiseled into the rock, probably using a tool made from petrified wood and a hammer stone.

Having โ€œearned by keep,โ€ we found some other stones to sit on and enjoyed a leisurely lunch basking in the warm desert sun.

Can you see the petroglyph?

Artifact Delights

After lunch, things really got moving, as we drew closer to a larger archaeological site in the area.

Diana spotted a small unionid bivalve shell, or mussel, from one of the many species common in the area.

Matt Walters also led us past a vertebra fossil and a collection of other fossilized bone fragments, as well as several fragments of broken pottery, before reaching the piece de resistanceโ€”the site of several ancient Puebloan pit houses. 

The mussel shell Diana found during the hike.

As Matt, Dorenda, Diana, and I neared what I later learned was a pit house village, we started seeing more pottery fragments, as well as several other archeological artifacts.

The pottery was of various colors and textures and used a variety of design elementsโ€”there were white and black pieces, fragments of grayware and corrugated pieces, as well as some decorative edges and unique shapes. Dorenda explained how some of the pottery would have been traded into the region, while other pieces were likely made by the local people.

Flakes from arrowhead and other tool-making also scattered the ground in colorful abundance. It was fun to pick out some favorite pieces to admire before moving to the next.

One of many pottery shards found during the hike.
`Flake of petrified wood found during our hike.

Pit House Village

The density of the pieces continued to increase as we neared a few mounds of rocky earthโ€”we had arrived at the pit houses. Matt Walters estimated that there were probably three dwellings in the area. And what a view! I guess the old adage โ€œlocation, location, locationโ€ฆโ€ is more ancient than I thought.

The pit houses themselves would have been built by stacking rock vertically and digging down into the earth. Then a roof would be fashioned out of whatever materials were available. There would have been a garden of squash, beans, and corn in the area and probably some storage pits as well. Though the pit houses were permanent dwellings, they were often only used seasonally.

Looking down on the pit house site. What a view!

Pit House Treasures

The areas around the pit house ruins contained many more archaeological treasures. Dorenda showed me a rounded stone, about the size of a human hand. โ€œItโ€™s a hammerstone,โ€ she said. โ€œYou can tell it has been used because it has chips in it.โ€ The stone was heavy in my hands.

We also saw several large grindstones comprised of a large flat stone, called a metate, and a smooth stone with a shape suitable for grinding.  The metate was ground down and smoother with use.

We also saw several unique pottery pieces, some so fragile that we avoided picking them up, including a small piece that had a handle and looked a bit like a ladle.

A hammerstone
A grindstone.
One of several metate found during our hike.
Fragment of pottery with handle.

Weather or Not

After visiting the pit houses, we slowly curved our way back toward the cars. There were still plenty of artifacts to see, including several intact arrowheads and many more flakes of petrified wood.  Matt Walters led us around to all the fascinating finds as we hiked.

We passed by another petroglyph site, before heading into a canyon between two flat topped Mesas. Though dry as a bone at the time, Matt and Dorenda told Diana and I how once they had found the canyon impassable from flood waters. โ€œThis was a roaring river,โ€ said Dorenda. Though rain might not be frequent in the area, flash floods do occur.

The lasting influence of rain could also be seen on the canyon wallsโ€”gullys and rills marked the paths of past water events. There were also large holes at the base of some of the hillsides, created by the movement of water along paths inside the Earth that widened over time.

Looking up, the hills wore sandstone capsโ€”created by the weathering of the softer mudstone below.  Giving the place an overall hoodoo-like quality.

Sandstone caps on top of softer mudstone.

The CCC

We continued to follow the dry riverbed into the canyon. Large jumbles of rocks lined our path most of the way.As I considered these large fallen stones, Matt Walters slowed his pace again. Sitting amongst the rocks was a long piece of wood.

Matt Walters inquiredโ€” โ€œWho had a big impact on the park?โ€ He asked.

โ€œThe CCC,โ€ he said, after some deliberation.

According to Matt Walters, the Civilian Conservation Corps were in the park from July 1934 to 1938. The long piece of wood was an artifact of that time. โ€œThe CCC had a flagstone quarry,โ€ Matt explained, โ€œwe think this is part of the quarry.โ€

In addition to the quarry, the CCC built the Painted Desert Inn and dug a 16-mile irrigation system in one yearsโ€™ time.  With current regulations and protection for archeological and paleontological resources stricter, it took three years to replace that same waterline in 2016.  Matt Walters chuckled at the irony.

A long piece of wood.

My Own Eyes

Just a bit further down the wash, I had my own fun. Hidden amongst the rocks, I made my first solo fossil discoveryโ€”another freshwater bivalve shell lay on the ground.  I called out to the rest of the group to share in my triumph. Then I took a few pictures of the fossil shell before placing it back on the ground for another to find. 

 A Few More Petroglyphs

As the sun sunk a bit lower in the sky, we entered the last leg of our journey which brought us to a couple more incredible petroglyph sites.

At one site there were several large stones decorated with at least a dozen figures, ranging from bear claws of various shapes and sizes to what looks like a coyote. Human figures were also displayed on the slab that was probably about as long as I am tall. 

Petroglyphs covered several large slabs of rock at this site.

The last petroglyph site was a bit more of mystery. Here a large rock was marked with several dot-arrays, a couple of straight-lined figures, and a set of zig zags as a border. The whole display seemed to be conveying some sort of information, but what? 

Matt, Dorenda, Diana, and I all puzzled over it, offering hunches and second guesses as to its meaning, before moving on.

Petroglyph with mysterious message.

Stone Tree

Just before hitting the road and leaving behind our backcountry adventure, I noticed a lone piece of petrified wood sitting quietly on the brown, cracked Earth.

Perhaps I was developing โ€œan eyeโ€ for this unique desert environment because I felt drawn to it. So much so that I snapped a quick picture.

A few moments later, after goodbyes and well wishes, I was back in my car, driving the lonely road to my home for the night.

Last picture of the day.

A Snapshot

The picture of the log is the last one that I took that day. Looking at it now, I still feel its call. A call to a time before the dinosaursโ€”to swamps and rivers hidden in a now desert landscape. To a time where people lived in pit houses and hand-crafted stone tools and beautiful pottery. A call to modern-day adventures and new friends. And finally, a call to return to this place someday in the futureโ€”to remember, while discovering the past, all over again.

Dorenda and Matt Walters are long-time volunteers for Petrified Forest National Park, guiding park guests on fabulous cross-country hikes each weekend. Diana Boudreau is a paleontologist and fossil preparator at Petrified Forest National Park. Matt Smith is the long-time museum curator for Petrified Forest National Park.