Date: January 20, 2018
Mode of Travel: Hiking on Foot
Distance: 3.3 mile loop
Elevation Gain: 445 ft.
Rocks: Redwall Limestone, Naco/Supai Formation, Basalt

Judy had asked me to join her on a hike on one of her favorite trails today. Since the trail head is literally only a couple hundred yards from THAT Brewery, of course I agreed. We were going to make our usual loop, but some industrious people have added a new trail that turns our usual 2.8 mile loop into a 3.3 mile loop. We decided to check out the new trail, and toast it with a THAT Trail Ale afterwards.

The trail head rests on the top of a layer of limestone known as “Redwall Limestone.” This formation is shared with the Grand Canyon and goes by the same name in both places. It was formed in the Mississippian Period, about 350 million year ago. At that time, the Payson area was very flat and had subsided under a tropical sea. This allowed mud and the remains of dead sea creatures (shells, bones, etc) to settle on the sea floor. Later this slimy mud turned into limestone.

How do I know we are standing on the Redwall Limestone? From my four years of observation, I’ve found two ways to know I am hiking in the Redwall:

• Often the limestone has a green tint.
• Often the limestone has been broken into fragments and cemented back together again with a red rock known as terra rosa. 

At the trail head, the limestone does not look green, but you can find limestone fragments with terra rosa adhered to it, especially to the South of the trail head, but you can find some fragments only a couple hundred yards up the trail:

A little further up the trail, the Terra Rosa disappears, and we find only gray limestone, grey or red sandstone, or sandy limestone. We are now in the Naco/Supai group:

Which is it? Naco Formation or Supai Formation? My geology professor told me it is called the Naco Formation around Payson, but it was laid down at the same time as the Supai Formation of the Grand Canyon. Many of the layers in this formation are shared between here and the Grand Canyon. I’ll call it the Naco Formation from now on.

The Naco Formation was formed in the Pennsylvanian Period, or about 310 million years ago. After the Redwall Limestone had been laid down, the seas subsided (or the land rose) so that Payson was no longer submerged. A few million years later, the seas returned (or the land subsided) and Payson was again under water. This time, however, Payson was very near the coast and the sea advanced and retreated repeatedly over Payson. Sometimes sea sand was laid down, sometimes limestone. Other times when Payson was above sea level, sand dunes marched over the land depositing sandstone.

We are going to stay in the lower Naco Formation for the rest of the hike.

After about a quarter mile, we come to our first trail junction and we are going to ignore the trail on the left and continue straight. Eventually, we leave the cleared fire break and enter a wooded area and immediately cross a stream:

We rarely find water in this stream, but because of two inches of rain in the past two weeks, it was flowing pretty good today. Notice the rocks in the foreground. They are basalt. How did that get here? We are hiking in a limestone and sandstone formation. Another half mile up the trail we will see where it came from:

The Mogollon Rim overlooking Pine is capped with several layers of basalt. These are ancient lava flows from a volcano somewhere up on the Rim. I don’t know exactly where the volcano[s] are located or when they erupted, but it must not be more than a few million years ago. The flows of lava from the volcano[s] must have flowed south, flowing over the rim (that must have been a sight to see!), and spread out onto Horseshoe Mesa below.

As the face of the Mogollon Rim weathered and eroded, it undercut the basalt layers above, and they tumbled down the face, collecting in the streams and washes. Since basalt is considerably more resistant to weathering than limestone and sandstone, that is why it fills this stream bed we are walking up. The limestone and sandstone boulders that tumbled down here have long since crumbled and washed away leaving only boulders of basalt.

We will see a lot of basalt for the next mile or so. If you take a close look at some of the broken pieces you will notice that most have “bubbles” in them:

These “bubbles” are called vesicles. The lava that flowed from the volcano[s] atop the Rim had a lot of dissolved gas in it that were kept in the molten rock due to the great pressure on it. When the magma reached the surface, this pressure was released and the dissolved gasses (CO2, H2O, et. al.) expanded creating vesicles which were frozen in time when the lava cooled.

As a side note, it is interesting that the ancient Indians of this area found this vesicular basalt very suitable for making metates and manos for grinding their foodstuffs into meal.

We come to a four-way trail junction:

We have always turned left here on the Lower Pineview Trail, but today, we are trying the new trail (Pineview Trail #28) straight ahead hugging the stream. After climbing a couple hundred feet in the next quarter mile, the trail winds around to the west, re-entering the fire break, and affording wonderful views of Pine and the Mazatzal Mountains. Eventually it descends and joins the Lower Pineview Trail. We turn right at this junction.

Back down in the woods, we reach the junction with the Pine Canyon Trail #26. We turn left here:

This trail takes us back to the Pineview Trail, where we turn right and return to the trail head. It is now time to head over to THAT Brewery to celebrate another fine hike.

In January, 2015, my wife, Judy, and I moved to Payson. I had recently retired from a 36 year computer software career with Raytheon Company, and we planned to make Payson our retirement home.

Knowing that I would have to find activities to fill the forty hours that normally took up my week while I was employed, I made a list of several things I wanted to do in retirement. Learning Geology was near the top of that list (right after hiking).

I had been an avid hiker since my forties, and watching my foot placement on the rocky trails of Shenandoah National Park got me wondering about those rocks. What kind of rocks were they? How did they form? How old are they? How did they get here?

I bought a beginning Geology textbook and read it cover to cover. What I learned was that every rock tells a story! Some of those stories are quite interesting! Plus, every rock is an actor in a much larger story – the physical history of the Earth itself!

Once I got to Payson, I enrolled in the only two geology courses that Gila County Community College offers: “Physical Geology” and “Geology of Arizona”, both taught by Professor Carol Jones. I began paying attention to the rocks on my several hikes each week. I started marking observations on maps.

While hiking today, January 19, 2019, I decided to create a blog and begin recording my geological observations around Payson in both photos and words. Bear in mind, I am not a professional geologist. If you are, and you notice something I get wrong, please please please contact me so I can correct it.

As a professional geologist recently told me, “Payson is a geologist’s paradise”. It has some of the rock layers of the Grand Canyon. It has volcanoes. It has a seam where two continents accreted together. It has ancient sea floor. All of these rocks are laid bare by Payson’s semi-desert climate.

I hope you enjoy my observations.

Chuck Eby