The Mesozoic and Me: The Roots of the Geological Love of My Life
Head of the Rocks Overlook into the Escalante River drainage. This is on the road between Escalante and Boulder, Utah
This is a view into the canyon system of the Escalante River. On this very spot, 39 years and 10 months earlier, I had my first geological awakening at the age of 17. The seeds to my lifelong love of geology had already been planted but, it was here, and on that day, that I could first see and understand the story that the rocks were telling. It was like a window to the ancient past had been opened for me. Earlier that Summer, I went on a week-long desert experience that was directed by Gary, a psychologist with the Nebo School district. He lived in my neighborhood and this week was a local church-related activity. He called it "Survival" and it certainly did have elements of a desert survival course. For me though, the "survival" part was just how to get drinks, snacks, and not die while going from swimming hole to swimming hole. All of this happened in the deep, shaded canyons that you can almost see in the landscape of this photograph. I spent the next three years of my life as an instructor in his program.
That summer would shape the rest of my life! It was that time, and in this place, that my education in geology began. I had three teachers on that day. There was Gary, who had read about the local geology, there was an information plaque that briefly described some features & concepts, and there was my fertile imagination. All three of them worked together to paint an image in my mind, of endless dunes in an ancient sand sea, or "erg", stretching out well beyond the horizon in every direction. This sand sea would be buried and lithify into the Navajo Sandstone Formation which fills nearly the entire view of the photo. Eventually, and from the East, the rising waters of an epicontinental sea, known to geologists as the "Jurassic, interior seaway", would eventually submerge the sand dunes with its warm waters and deposit the fossil-bearing mudstone that I was standing on.
Beneath the Navajo Sandstone, other layers of rock tell the story of this part of the continent through the Lower Jurassic and Triassic times. Above it, the rest of the Mesozoic is represented. This area, has some of the most complete record of the Mesozoic exposed anywhere on Earth and, for me, the Navajo is at its heart.
The Escalante River has become famous for its canyons cut into the Navajo Sandstone. Many of these are slot canyons. These narrow canyons are actually an entrenched river system. The river and its tributaries formed on a flat surface as a meandering system. Several million years ago, the crust in that region experienced uplift. As the crust rose, the river maintained its gradient, carving the canyons. Imagine lifting a stick of soft butter upwards past a warm knife. The effect would have some similarities.
To the southwest, in the vicinity of Zion National Park, the uplift was so great that the softer rocks which underlie the Navajo Sandstone were exposed. Incidentally, this is also where the Navajo is the thickest. The more rapid erosion of these older, softer rocks, undercut the Navajo allowing massive slabs of sandstone to shear off and fall away. This is why the cliffs at Zion are so steep.
That summer would shape the rest of my life! It was that time, and in this place, that my education in geology began. I had three teachers on that day. There was Gary, who had read about the local geology, there was an information plaque that briefly described some features & concepts, and there was my fertile imagination. All three of them worked together to paint an image in my mind, of endless dunes in an ancient sand sea, or "erg", stretching out well beyond the horizon in every direction. This sand sea would be buried and lithify into the Navajo Sandstone Formation which fills nearly the entire view of the photo. Eventually, and from the East, the rising waters of an epicontinental sea, known to geologists as the "Jurassic, interior seaway", would eventually submerge the sand dunes with its warm waters and deposit the fossil-bearing mudstone that I was standing on.
Beneath the Navajo Sandstone, other layers of rock tell the story of this part of the continent through the Lower Jurassic and Triassic times. Above it, the rest of the Mesozoic is represented. This area, has some of the most complete record of the Mesozoic exposed anywhere on Earth and, for me, the Navajo is at its heart.
The Escalante River has become famous for its canyons cut into the Navajo Sandstone. Many of these are slot canyons. These narrow canyons are actually an entrenched river system. The river and its tributaries formed on a flat surface as a meandering system. Several million years ago, the crust in that region experienced uplift. As the crust rose, the river maintained its gradient, carving the canyons. Imagine lifting a stick of soft butter upwards past a warm knife. The effect would have some similarities.
To the southwest, in the vicinity of Zion National Park, the uplift was so great that the softer rocks which underlie the Navajo Sandstone were exposed. Incidentally, this is also where the Navajo is the thickest. The more rapid erosion of these older, softer rocks, undercut the Navajo allowing massive slabs of sandstone to shear off and fall away. This is why the cliffs at Zion are so steep.
The Virgin River Gorge at Zion National Park is entrenched into the Navajo Sandstone.
Let's take a look at some of the more well known rock formations below the Navajo. These formations are all parts of the regional landform known as the Grand Staircase. Below the Navajo is the Kayenta Formation, which is underlain, in places by the Wingate Formation. Beneath the Wingate is the Chinle Formation and then the Shinarump conglomerate, which lies upon the Moenkopi Formation. All of these are Triassic rocks. I think that the whole stack of rocks shows up best at Capitol Reef National Park. You can click on the rock formation names above to link to pages which discuss them.
Triassic sequence of rocks at Capitol Reef National Park, Utah
My first real adventure in Utah's canyon country was to Capitol Reef National Park when I was 16 years old. My best friend and I went there for a road trip. Since then, I have returned to visit the Mesozoic rocks of Utah more that any other rocks anywhere. These rocks, and the scenery that they create, have become a major destination for tourists from all over the globe
