The "Fingers" of Zion: Another Quiet Corner of a Crowded National Park

My last few posts have been about finding some quiet corners in one of our busier national parks, the one at Zion Canyon. Sometimes one finds solitude by following popular trails at less popular hours, or by following where the trams go (but not where they stop). One can also explore a number of roads in isolated corners, including the Lava Point Overlook, and today's destination in the Kolob Canyons section of the park. I didn't make it there last month, but paid a visit a couple of years ago.

The Kolob Canyons are a northwest outlier of the park, accessed from Interstate 15 between the towns of St. George and Cedar City. There is a small visitor center just off the freeway, and a five mile long road that winds over the ridge to a series of overlooks and trailheads.

The cliffs are composed of the same beautiful Navajo Sandstone that forms the cliffs of Zion Canyon, but here they form a 2,000 foot high escarpment with a series of incised canyons, sometimes called the Kolob Fingers. The escarpment is there because of the presence of a major fault that forms the boundary between the Colorado Plateau and the Basin and Range Province, the Hurricane Fault.

The Kolob Canyons are considerably higher in elevation than the main canyon at Zion, and are proportionally greener as a result. The creeks that carved the canyons were smaller, but several form beautiful alcoves and slot canyons. Trails lead out in several directions, most notably at Taylor and LaVerkin Creeks.

A few of the canyons haven't cut down very far at all, leaving behind hanging valleys, and under the right conditions, high waterfalls. There was just the smallest trickle the day I was there.

There are actually two fault systems in the immediate vicinity. The more recent Hurricane Fault was caused by tensional stress as western North America moved northwest away from the rest of the continent. But during the late Cretaceous, the region was being compressed by subduction zone activity from the west. The Taylor Creek Thrust Fault formed at that time. It's exposed near the road in several places.

One of my future wishes is to explore some of the backcountry destinations of Zion National Park; there are gigantic arches and strange and wonderful slot canyons like the Subway to explore. One of the great adventures is to walk the entire length of the Narrows of the Virgin River. I haven't yet had that privilege...

The Kolob Canyons are of a character completely different than the main park at Zion Canyon, both in scenery, and in solitude. If you ever are traveling I-15 towards Cedar City, don't miss it!

Our journey this past June was almost over, but a few wonders still awaited us, out there in the Basin and Range and over Tioga Pass. Watch for the next post!

A Land of Strange Standing Stones, and an Odd Connection to the Grand Canyon

There are a lot of strange landscapes on the Colorado Plateau and otherworldly scenes. Some are famous enough as to not surprise first time visitors, such as the spires and hoodoos at Bryce Canyon National Park. But others are hidden, strung along gravel roads far off the beaten track. Seeing them for the first time comes as a shock. These rocks just aren't "normal". 

The largest single park in the Colorado Plateau region is also one of the least familiar. Really, how many of you have heard of Grand Staircase-Escalante National Monument? It covers a huge swath of land north of Grand Canyon and Glen Canyon National Recreational Area, west of Capitol Reef National Park, and south of Bryce Canyon. It was controversial in its birth, as have been most of our National Monuments, but it is indeed worthy of protection. We are only just beginning to discover the treasures that lie within its borders.

Our journey on this day would take us from Glen Canyon Dam to Bryce Canyon National Park via Cottonwood Wash Road, a gravel track that runs for thirty miles along the East Kaibab Monocline, known here as the Cockscomb.

Part of the Cockscomb (East Kaibab Monocline) courtesy of Google Earth

A monocline is a step-like fold, flat on either side and flexing in the middle. Such folds often develop where fault moves beneath horizontal sedimentary layers. The Cockscomb is an extraordinary example of one of these features, with a vertical separation of nearly a mile (erosion has leveled off much of the uplifted rock, so the actual elevation change across the fold is much less). The fold is also very long. It extends for 150 miles and actually forms the eastern edge of the Kaibab Plateau where the Colorado River turns west to form the deepest part of the Grand Canyon. It formed during the Laramide Orogeny in Late Cretaceous-Early Paleogene time.

From Wikipedia

The rocks within the monocline have been twisted so much that the layers are vertical. They have also been attenuated (stretched) so that some of the layers are thinned out. The rocks have been brecciated (crushed) to some extent, which provides a probable explanation for the strange towers and pinnacles found here and there along Cottonwood Wash Road. Groundwater following the fractures would have left mineral deposits that had the effect of reinforcing and cementing some of the most deformed rocks. Erosion removed the surrounding softer rocks leaving behind the towers and spires.

Pareidolia is the tendency of humans to build patterns out of randomness, seeing things that aren't really there: faces in clouds, and human or animal figures in rocks. Who does the rock below bring to mind?

The final rock in our little mini-tour of the Grand Staircase is Grosvenor Arch, which is really two arches, and which once was called Butler Arch until people on an expedition with the National Geographical Society decided to name it after their boss. They apparently had more pull with the Board of Geographic Names. It's not part of the monocline, but is instead at the boundary between two layers of different erosional resistance. The upper rock is a conglomerate equivalent to the early Cretaceous Cedar Mountain Formation, while the lower layer is the Henrieville Sandstone of Jurassic age. The largest opening is 152 feet high and 100 feet wide.

Lastly I have pictures of flowers. Despite the ongoing drought, there were some beautiful wildflowers blooming in one of the side canyons we explored. There were Evening Primroses...

...and some beautiful Sego Lilies, the state flower of Utah.

Tse' bighanilini and Hasdestwazi, "the place where water runs through rocks", and "spiral rock arches."

Glen Canyon was a beautiful, magical place that was unceremoniously flooded under the waters of Lake Powell (and I'm pretty sure John Wesley Powell would have been appalled that his name was given to the lake). Despite the gigantic eyesore of Glen Canyon Dam, there are some incredible places to explore in the immediate vicinity. One of them is Antelope Canyon, one of the Tribal Parks managed by the Navajo Nation. The two parts, upper and lower, of the canyon are called Tse' bighanilini, which means "the place where water runs through rocks", and Hasdestwazi, or "spiral rock arches."

Natural arch within Lower Antelope Canyon

Each of the canyons is worth a look. The upper canyon is justly famous for the noon hour beams of sunlight piercing the near total darkness of the deepest passages. It is also level from one end to the other. But it also requires a ride from town that includes an unbelievable race up a pure stretch of loose dune sand. And it is crowded, especially during the aforementioned noon hours when you might find yourself standing shoulder to shoulder with hundreds of other people. It's not a place for the claustrophobic.

On our recent tour, we opted for the lower canyon. It doesn't have the piercing beams of sunlight, and it is not level, requiring steps and ladders for access. But you don't have to be ferried up Mr. Toad's Wild Ride, and it tends to be far less crowded (in my three trips, anyway).

The tours of these incredibly beautiful works of nature begin beneath the shadow of the monstrous coal burning power plant just outside of Page. The coal mines are sixty miles away, but the energy infrastructure is here near Glen Canyon Dam. We were given a short safety lecture before walking down the end of the lower canyon.

It's hard to believe that such a treasure lies hidden in these folds of crossbedded Navajo Sandstone. The canyon is more than a hundred feet deep in most places, but only a few feet wide at the top. The guide politely asked us not to jump across the top of the canyon, prompting me to wonder what story was behind that rule...

Antelope Canyon drains an area of dozens of square miles, but the rushing waters of the occasional flash floods are forced to cross two ridges of Navajo Sandstone. The rock is cemented well enough to form vertical cliffs, but at the same time the sandstone is easily and quickly eroded by fast-moving sediment rich water. The result is an incredible labyrinth of looping and curving channels.

The natural curves of the canyon are accentuated by the crossbedding of the Navajo Sandstone. The Navajo formed as a gigantic sand dune sea that extended from Wyoming and Colorado to Nevada and eastern California. The crossbeds are the preserved slipfaces of the sand dunes. The dunes were present during the Jurassic Period, when dinosaurs wandered across what is now the southwest United States.

The narrow canyon can be dangerous. Storms that are dumping floodwaters upstream might not be visible from the parking lots. After a horrific tragedy in 1997 that caused the deaths of eleven people, rescue measures have been put into place, and tours aren't offered when rain threatens the headwaters region.

The canyon is full of abstract shapes and forms, and a photographer could wander for hours through the passageways (two hours to be exact, for an extra fee). Photography is allowed and encouraged by the guides, and they offer advice on shutter speeds and the like. It's been said that one can't take a bad picture here, but believe me, it's more than possible! The sharp contrast between light and dark wreaks havoc with photo framing. It challenging, but wonderful fun as well.

My favorite pictures occur where the sunlight is indirect and reflecting from above. The resulting yellow and golden hues are beautiful; the rocks seem to glow with inner light.

The texture and light are unique. If you are ever in Page, don't be afraid to put out the tour cost (between $20-35, with a $20 premium for those noontime tours in the upper canyon).

As is usual with my visits to the canyon, I have more pictures then I have words. Enjoy!

For the second time in my three tours through the lower canyon, our guide offered some beautiful flute music in the deepest part of the canyon. Here's the video:

Then it was time to go. We climbed up the last ladder into the blinding sunlight.

Out in America's Never Never: A Tale of Two Towers (and a few more)

Agathla Peak north of Kayenta, Arizona

America's Never Never is full of strange and wonderful sights. We had left the forested Black Mesa and its rather depressing strip mines and headed east to the village of Kayenta on the Navajo Reservation, then turned north towards Utah. We had dropped several thousand feet and were traveling through a more barren landscape (the barrenness exacerbated by the ongoing drought).

Now, before I go much farther, I need to talk about childhood cartoons. I surely date myself severely when I note that my favorites were the Looney Tunes, especially Bugs Bunny, but there was a special place in my heart for Wile E. Coyote and that nefarious arrogant Roadrunner.  I had been to places like Joshua Tree National Park and the Mojave Desert, so I knew that no desert really looked at all like those cliffs and spires that Wile E. was always falling off of.

At least not until I reached the Navajo Country around Kayenta and Monument Valley. Suddenly I was standing not only in a Roadrunner cartoon, but John Wayne would be riding up any moment in a stagecoach. There really were towering spires in the desert!

I was pretty lucky in that my parents were the ones who originally introduced me to this country on our family vacations. I learned about these deserts in my childhood, but I was left with a lot of questions not readily answered. It wasn't until I became a geologist that I fully appreciated the processes and history that produced these incredible landscapes. And I've been bringing my students here ever since to show them that deserts aren't just cacti and sand dunes.

Agathla Peak just north of Kayenta

There are different kinds of "towers" in Navajo country produced by quite different processes. There is a great spot on Highway 163 about ten miles north of Kayenta to compare the two. To the east is Agathla Peak (or "El Capitan") standing some 1,300 feet over the highway (above). To the west stands Owl Rock (below).

Agathla is one of the more spectacular examples in the Navajo country of a volcanic neck or diatreme, the core of a deeply eroded volcano. Although the towering spire appears dark it is mostly composed of large chunks of sandstone that collapsed into the interior of the volcano after a violent explosive eruption. One can see dark dikes of basaltic-looking volcanic material; the rock is called minette, which is a relatively rare potassium-rich volcanic rock. The network of dikes protected the core of the volcano while the remainder was eroded away. The intrusion is just one of dozens covering an area of around 20,000 square kilometers around Four Corners called the Navajo Volcanic Field. Shiprock is perhaps the most familiar of these features.

Owl Rock, the tower on the other side of the highway,  is quite different. It is clearly layered, and the layers are horizontal. It is an erosional outlier of the same sequence of sandstone, siltstone and shale that can be found in many of the cliffs throughout the region. Sedimentary rocks are not known for producing towers and spires under "normal" conditions (read "characteristically humid conditions where most people live"). In the dry desert environment of the Colorado Plateau, resistant rocks such as lava flows or in this case quartz sandstone will form a protective cap that generally prevents the otherwise rapid erosion of the softer underlying sediments.

The tower is composed of Triassic and Jurassic-aged rocks of the Kayenta and Navajo Sandstone formations. Beneath the tower are the siltstone and clays of the Triassic Chinle Formation (or Group). The Chinle was laid down in floodplains and lakes in the earliest years of the dinosaurs. Distant volcanic eruptions (some near my own Sierra Nevada) laid down ash deposits that have oxidized into colorful red, brown, yellow, and lavender clay-rich strata. Some of the ash layers are famous for their petrified logs, most notably at Petrified Forest National Park in Arizona. We have seen logs in the vicinity of Agathla Peak and Owl Rock as well.

But what about the cliffs? How did they form?

The Navajo Sandstone is a solid rock but when it is stressed by regional deformation it tends to develop vertical fractures called joints. The Navajo may prevent the rapid erosion of the underlying shale layers, but the rocks do eventually get eaten away, undercutting the sandstone. The rock falls away along the joints in a process called cliff retreat. In this way a plateau shrinks to become a mesa, a mesa becomes a butte, and eventually only a spire remains.

It turns out that Owl Rock is simply a foreshadowing of the incredible sights ahead. As we passed into Utah we reached Monument Valley, a place where cliff retreat has produced a spectacular array of mesas, buttes and spires. The formations are different because we have crossed onto a deformed section of crust called the Monument Upwarp. We have reached rocks that are late Paleozoic in age (Permian), between around 250-300 million years.

At Monument Valley, the vertical sandstone cliffs are composed of the DeChelly Sandstone. A thin layer called the Shinarump Member of the Chinle Formation forms the top layer of many of the spires and buttes. The gentler slopes below the cliffs are the finer sediments of the Organ Rock Shale. The Permian Period was a time of reptiles, but not dinosaurs. The terrestrial environments were dominated by a group called the Therapsids, or "Mammal-like" Reptiles. These animals had a more vertical stance that distinguished them from the sprawling gait of other reptiles, and a number of other features that are mammalian in nature, including differentiated teeth. They gave rise to the mammals in Triassic time. The region has yielded up a number of specimens.

Monument Valley is a tribal park administered by the Navajo people. Many people (who don't know who John Wayne was) will know the place as the spot where Forrest Gump decided to stop running across America ("What are we supposed to do now?").

We had a lecture at the overlook and headed up the highway to a sight that was an absolute first for me, the Valley of the Gods. More on that in the next post!

Out in America's Never Never: Erg-onomics of a Desert Park

That's right, geologists can't help themselves. They like puns. This isn't a discussion of how to sit properly in a national park, or to hike without causing carpal tunnel syndrome in your toes. It's about sand, lots and lots of sand. Enough sand to cover as much as 625,000 square kilometers (about 240,000 square miles). My home state of California totals a little over 420,000 square kilometers, to give a bit of a comparison. Large "seas" of sand dunes are called ergs.

On our second day out in America's Never Never, we had reached Zion National Park in southern Utah. The park is justly famous for the sheer cliffs that tower over the valley floor, and for the beautiful scenery along the Virgin River. The scenery exists primarily because of one formation: the Jurassic aged Navajo Sandstone. The bold cliffs which sometimes have sheer drops of 2,000 feet (600 meters) are composed of cemented dune sands of an erg that once extended from southeastern California to Wyoming and Idaho. There are few if any places like it in the world today.

This vast amount of sand had to come from somewhere. Recent studies have demonstrated that it was probably eroded from the Appalachian Mountains and transported by rivers to the Midwest. The evidence is mineralogical, but it also makes sense because the eastern mountains were the only range in Jurassic time with enough elevation and extent to account for the approximately 60,000 to 140,000 cubic kilometers of sand (14,000-34,000 cubic miles). Some material may have come from the rising Sierra Nevada magmatic arc, but that range was small in comparison.

The Navajo Sandstone ranges in color from pure white to dark reddish-brown. Iron oxide minerals provide the color. Their presence may be related to petroleum that may have once existed in the unit (if it did, it would have been a resource to dwarf Saudi Arabia).

Zion National Park is just one of the spectacular exposures of the Navajo Sandstone to be found in the Colorado Plateau region (our stop in Valley of Fire also was in the same unit). It is in Zion that the greatest thickness of the unit is achieved, and the scenery is truly grand. A visit to the park should always include an exploration of the Narrows of the Virgin River, and if one is in good shape, a visit to Angels Landing or Observation Point is a great idea. If one is straining one's neck by looking up at the cliffs, a drive to Lava Point is in order. From the end of the gravel road, one can look down into the canyons from above.

Photo by Mrs. Geotripper

If you are having trouble imagining the sand dunes themselves, hop on over to nearby Coral Pink Sand Dunes State Park to the east of Zion National Park. We did, and had a great time looking at (and playing in) recycled Navajo Sandstone. The park has examples of several types of dunes, and has areas of active dune formation and migration as well as dunes that have been anchored by vegetation.

Photo by Mrs. Geotripper

Coral Pink Sand Dunes are far too limited in extent to be considered an erg (in the United States, only the Algodones Dunes of Southern California are considered to be of sufficient extent at 800 square kilometers). It is fascinating to think that the sand of which the dunes are composed once was carried in a Mississippian-sized river from a vast mountain range in the eastern United States, formed dunes in one of the largest sand seas ever to exist on the planet, was locked in solid rock for 200 million years, and only a few thousand years ago was released to bounce in the wind once again.

Photo by Mrs. Geotripper

Vagabonding Across the 39th Parallel: Sun and Rock in Arches National Park

Last summer we set out on a vagabonding journey that roughly followed the 39th Parallel across the western states of Nevada, Utah and Colorado. By vagabonding, I refer to the set of loose rules we followed to not plan more than a day or two in advance, and try to see as many new sights as we could see. We ultimately made it to Rocky Mountain National Park, and now after 10 days on the road, we were headed west, slowly returning home to California.  Our winding road brought us to the town of Moab, Utah, and Arches National Park. We were now on the Colorado Plateau, a vast area of the earth's crust that was stable for hundreds of millions of years, but in recent geologic time has been uplifted and deeply eroded by the Colorado River and her tributaries.

I've been to Arches National Park a great many times, but almost always with a large group of students. A group necessitates some serious planning, and our trips usually include the same three places: a hike to Delicate Arch for the sunset, a hike to Double Arch, and a hike to Landscape Arch, the largest in the park (and probably in the world). On this particular day, our new experience was stopping and sitting at one of the less iconic viewpoints. Literally sitting, for a rather long time. We had a picnic dinner, and just experienced the desert while the sun set behind us. 

Before settling in, we made a quick circuit past the La Sal Mountains overlook and the Windows Section. The La Sal Mountains are outside of Arches National Park, but provide a spectacular backdrop to arches and fins that make up most of the scenery in the park. The mountains have an unusual origin. They are not quite volcanic in origin (although volcanoes almost surely existed here, but have been eroded away), but instead are formed of intrusive rock that reached shallow depths in the crust, wedging and bulging up the sedimentary layers that lay above the molten rock. The intrusions are called laccoliths. The mountains rise to 12,000 feet, and are often snow-covered, even in early summer.

The Windows Section contains several large arches, including Double Arch, made famous by the opening scenes of Indiana Jones and the Last Crusade. There is no deep cave up in the alcove, and no Coronado's Cross, though. Just a spectacular double arch. It's big; click on the photo below and look for the people walking under the arch.

The Windows Section is a good place to learn the stratigraphy of Arches National Park (see the picture below). There are three important sedimentary layers that are fundamental to the scenery, all Jurassic in age. The Navajo Sandstone is the preserved remains of a vast dune sea (an erg) that developed along the western edge of the supercontinent Pangea. It makes up much of the spectacular scenery at other parks like Zion and Capitol Reef, but is less visible in Arches. It makes up the lighter-colored layer at the base of the slope in the picture below.

The layers atop the Navajo Sandstone are two members of the Entrada Sandstone: the Dewey Bridge member and the Slickrock member. The Dewey Bridge formed in a tidal flat environment and has variable layers of siltstone and sandstone. It is easily eroded, which allows it to undercut the harder Slickrock member, causing the cliffs and fins in which the arches are developed. It often has a wavy "crinkled" aspect that has led some geologists to speculate that the layer was affected by the nearby impact of an asteroid at Upheaval Dome. The speculation is controversial, but the explanation appeals to me simply on the scale of grandeur and in thinking outside the box.

The cliffs at Arches are made of the Slickrock member of the Entrada Sandstone. The formation preserves sand dunes that developed along the coast of Pangea (much like the Navajo Sandstone). The arches form most often in the Slickrock member. I wrote about the formation of the arches in my series Time Beyond Imagining. Here is a short excerpt:

"The origin of the park's famous arches (there are hundreds) is tied to the salts of the Paradox Basin. The salt beds are thousands of feet thick, and when placed under pressure, can slowly flow upwards through the overlying rock, forming domes and anticlines (upward pointing folds). Over millions of years, erosion removed thousands of feet of overlying sediment, and the salt was close enough to the surface to be affected by groundwater: it was dissolved away. The tops of the folds collapsed inwards, and the Entrada Sandstone was fractured (jointing) into a series of parallel fins. A large northwest trending anticline crosses the park; most of the arches occur along the flanks of the anticline.

The top of the fins are exposed to the arid desert climate, where the rock dries quickly following the infrequent storms. At the base of the fins, where the rock is buried by soil and loose sand, the rock may stay moist much longer. This leads to the solution of the cement holding the sandstone together, and the fins start to weather from below. Eventually a small window may open up, and falling slabs of rock enlarge the opening."

The sun was sinking lower towards the horizon. We sat in the silence and ate our sandwiches; a few cars stopped briefly and people stepped out to see what we were looking at, but they were mostly in a hurry to be someplace else.

Arches is an elemental place, as most desert landscapes are. There is sunlight, and there is rock. Everything else is secondary, the plants, the animals, the people. If you are caught in the open on a hot summer day, the elements are perilous. Survival is a crapshoot. In our insulated existence, the crapshoot becomes a source of great beauty, especially as the sun sinks and the searing heat dissipates. The rocks glow, and then slowly fade to darkness.

Our minds see meaning in the random shapes of the rocks, and we make stories of their origin. Some stories involve myths and heroes, while others involve jointing and frost wedging. I enjoy both kinds. What do you see here?

The fire in the sky died away, and stars emerged in the darkness. We gathered our things and drove back into town.