Dreams of Summer and Southwest Travels: Grand Stories Exposed in a Canyon

No one place on Earth can ever tell the whole story of the Earth. But there are lots of places that tell part of the story. That's the fact that makes geology one of the most fascinating sciences there is. It's an incredible detective story that must be pieced together from disparate bits and fragments that must be correlated and organized into a coherent narrative. Some places tell more of the story than others, and some places do it in a fashion that is awe-inspiring. Grand Canyon is one of those places. It is one of the greatest places on the entire planet to teach the basic principles of geology. The geology is in your face, exposed perfectly, largely free of soil and vegetation, and yet the canyon is still a place of mystery and unsolved questions.

We are in the depths of winter this week, so I've been traveling back through the photo archives for a look at warmer times, our field studies trip to the Colorado Plateau last summer. We spent two days on the South Rim of Grand Canyon, which barely gave us time to scratch the surface of the fascinating place.

For me, a nice moment came while staring into the depths of the canyon from Lipan Point. The view, seen in the first picture, reveals a labyrinth of tributary canyons, but the Colorado River is visible in the center of the photo. I zoomed in (photo two). What's remarkable about this one spot is that it is one of very few flat open areas on the floor of the Grand Canyon. It's called the Unkar Delta, and I have wonderful memories of an exploration there two years ago.

The "delta" (really kind of an alluvial fan) formed as debris poured onto the canyon floor from Unkar Creek. It is one of the few arable spots in the depths of the canyon, and the Ancestral Puebloan people utilized the soils to grow food there for more than three hundred years, from about 850 to 1200 AD. We stopped there during my one and only rafting trip down the Colorado River 813 years later in 2013. I wrote about the spot in my blog series "Into the Great Unknown". It was around 112 degrees as I explored the ruins that dot the delta, while the rafters scouted Unkar Rapid. The rapid is one of the first of the big rapids one encounters in the canyon, rated as high as 7 out of 10 on the difficulty scale (we made it through without incident other than getting wet, which was a relief in the sweltering heat).

The deep maroon color of the canyon walls at Unkar Delta reveals an interesting period of the Earth's history. The rock is part of a layer called the Dox Formation, which was deposited in estuaries, tidal flats, and deltas during the Mesoproterozoic era, just over 1.1 billion years ago. The rock is mostly composed of easily eroded shale and siltstone, which explains the open aspect of this part of the canyon. The Dox also contains fossils.

Life existed on Earth a billion years ago, but it was only of the simplest forms, algae and bacteria. The algae grew on pebbles in tidal flats, and as the tides ebbed and flowed, mud stuck to the algae-covered surfaces eventually forming layered structures called stromatolites. The stromatolites seen in parts of the Dox formation are among the oldest fossils found in the American west.

The Dox is part of a larger sequence of tilted layers in the Grand Canyon called the Grand Canyon Supergroup. The Supergroup is upwards of 12,000 feet thick, more than twice the depth of the canyon itself. How do the rocks fit in the canyon? They've been tilted and subsequently eroded. The exposures can be followed for a number of miles along the river in the depths of the canyon, but they have otherwise been covered by 4,000 feet of later (Paleozoic) sediments deposited between 540 and 250 million years ago. The rocks are fascinating to study, but the only way to do it is to hike to the bottom of the canyon, or raft the river (I've had the privilege of doing both). They can easily be seen from viewpoints in the eastern part of the canyon on both the north and south rims.

The Grand Canyon region exposes more than sedimentary rocks. There are numerous faults and folds throughout, including the unique monoclines, folds that are draped over step faults. One can be seen as the dark ridge in the middle of the photograph below.  Volcanism is a part of the story of the Grand Canyon as well. The peaks on the skyline in the same picture are the San Francisco Peaks, a group of cinder cones and a very large stratovolcano. Humphreys Peak, the high point on the rim, is the highest mountain in Arizona at 12,633 feet (3,851 meters). Prior to extensive erosion, the peaks may have exceeded 16,000 feet. The origin of the this massive volcano is somewhat enigmatic. The volcanic field is youngest on the eastern side, suggesting a possible origin as a hot spot in the mantle.

The volcanoes are more easily explained in the western Grand Canyon, far away from the tourist haunts. Crustal stretching has caused extensional faults to form (normal faults), allowing magma to rise from the underlying magma. Some of the lava flows spilled over the rim into the canyon, forming gigantic lava dams that produced giant lakes that extended hundreds of miles upstream.

The Paleozoic rocks (541-251 million years) of the Grand Canyon are mostly horizontal layers, and include limestone, sandstone, siltstone, and shale recording the transgression and regression of shallow seas across the region. A mountain-building episode took place in the region around 300 million years ago. The bright red and brown sediments of the Supai Group record the erosion of the Ancestral Rocky Mountains, and deposition in floodplains and deltas in the Grand Canyon region.

The origin of the canyon itself, and the carving of the rocks by the Colorado River perhaps are the biggest mystery for those who study the geology of the region. The river carved the canyon, but it's not entirely clear which Colorado River did the work! Different parts of the river system formed at different times, some many tens of millions of years ago, and other parts only 4 million years ago. It's a complex story, far beyond the scope of this short post, but I highly recommend the book by Wayne Ranney on the subject, available here: https://www.grandcanyon.org/shop/online-store/geology/carving-grand-canyon-evidence-theories-and-mystery-2nd-edition-wayne.

We took a break at Desert View at the east end of the canyon, and headed down the highway. There was a lot more to the Colorado Plateau than the Grand Canyon, as spectacular as it is.

Want a Wilderness Experience in Zion Canyon? Go Where the Trams Go.

Not where they stop, mind you, but where the trams go. Zion National Park underwent a huge change in 1997 when the park service closed the upper canyon of Zion to private vehicles and instituted a system of free tramways. The change brought an end to my favorite activity of night hiking in the upper canyon, and it at first seemed inconvenient when dealing with large student groups. But it didn't take me long to deeply appreciate the changes that came about in the upper canyon as a result.

For one, the animals became far more easy to see. On summer days, every available parking spot and pullout along the road would be filled with people, and the animal life would simply hide out. Without the constant commotion, animals felt more comfortable being out, and the tram rides now offer chances to see rabbits, deer, coyotes, foxes, and turkeys, while the tram drivers report seeing other more rare animals like mountain lions and badgers.

My recent trip to Zion afforded me some extra time to explore some new places, and I took the opportunity. The day started with a normal tourist target, the Gateway to the Narrows and the Riverside Walk. It is pretty much the most popular walk in the park, and is well worth seeing, even if it is crowded.

Zion Canyon is relatively wide in the lower reaches because the layers beneath the Navajo Sandstone are easily eroded, undercutting the high cliffs and causing rockfalls. It's where the Virgin River flows entirely in Navajo that the canyon gets incredibly narrow and very deep, with vertical walls reaching 2,000 feet above the river. The Riverside Trail is a paved ADA accessible trail that follows the narrowing canyon, ending after a mile at the entrance to the Narrows, where no trails are possible, but people can explore miles upstream as long as they don't mind getting wet numerous times.

Lots of water enters Zion Canyon from cliffside springs, and the hanging gardens can be very colorful. The Columbines are some of my favorite flowers. Don't worry about the feeling that you are being watched. It's either a Mountain Lion, or one of the Rock Squirrels. I don't which one is more menacing...

The trail is just gorgeous. But if the crowds bother you, there is a neat little secret for finding seclusion in the midst of the very busy national park. Like I said, walk where the trams go. Not where they stop, but where they travel between stops. You can walk along the road, or in many places a foot path follows close to the river. A tram will pass every 10 or 15 minutes, but that will be it for the motorized noise. I had two more hours to play with so I decided to walk as far down the canyon as I could.

I first passed the empty parking lot at the Temple of Sinawava, the end of the paved highway. I remember so many harried efforts to find parking for four vans on trips in years past, with hundreds of people hanging about, unwilling to give up their precious parking spots. Today it was quiet, because the moment the tram pulls up, people get out and immediately disappear up the trail.

Walking down the road, I was immediately struck by how unfamiliar the canyon looked. Walking is slow, giving one a chance to look at cliffs from new angles and new perspectives. I never saw this sort of thing from a car window.

The cliffs seem to change character every few hundred yards, with some cliffs sheer and unbroken, and others broken up by jointing. The air was fresh and the canyon bottom was still cool as the morning sun had not yet reached the floor of the gorge.

The emerald green cottonwood trees provided a strong contrast to the reds and browns of the canyon walls, and all of it was reflected on the waters of the Virgin River. Even the sound of flowing cascades felt unfamiliar and strange, but it was delightful as well.

Zion has been compared to Yosemite, only it's red and without the glacial origin. Maybe. I like to see each park on its own terms. Zion is a beautiful and stunning canyon.

I noticed a park tram stopped in an unlabeled pullout. It turned out to be a ranger tour, and I found out about an attraction in the canyon that is not on any of the park maps. It's called Menu Falls, and it is a delightful small waterfall just a few yards from the road. There is even a trail and platform for viewing, but to get there you either have to walk like I did or take the ranger tour. The name derives from the fact that early menus at the park lodge had a picture of the falls on the cover.

I happened upon a park ranger with a spotting scope looking for California Condors. The birds were once very much on the verge of extinction, down to just 22 individuals in the 1980s, but with a captive breeding program, they are making a comeback. Today there are more than 400, with more than 200 returned to the wild. The numbers may be close to their pre-European contact population. They are truly a relict Pleistocene creature, though, and would have been far more numerous during the Ice Ages, when the larger megafauna like giant bison and wooly mammoths would have provided much more food.

I'm sorry to tease you with the picture though. It's actually a Turkey Vulture. The ranger hadn't seen any this season yet. The upper canyon is also a good place to watch for Peregrine Falcons.

Around the next bend, the Great White Throne came into view. One of the tallest cliffs in Zion, it rises 2,300 feet above the valley floor. No trails reach the summit.

Zion is not known for Ancestral Pueblan ruins, but they are there, in a few spots. I had always seen one briefly through the car and tram windows over the years, but this walk was the first chance I ever had to photograph it. It appears to be a single granary, but was on a pretty steep cliff, so I didn't investigate further.

I reached the Weeping Rock tram stop, and time had run out. I'm pretty sure that next time I get the chance, I'll be walking down canyon from there. Who knows what else there is to discover?

Out in America's Never Never: A Corner of the Navajo Nation Where the Ancient Ones Dwelt

One thing I love about blogging is the total freedom be distracted and leave projects unfinished. This is something I inadvertently did six months ago. I got distracted by a river trip down the Grand Canyon and four field trip classes to the Cascades, the Sierra, and the California Coast. But I'm back to try and finish a series on my other incredible trip this last year: a journey through America's Never Never with a group of my geology students. You can catch up with the earlier posts by clicking here.

As I said in the original post, the Never Never is a remote and largely inaccessible part of the Northern Territory and Queensland of Australia's Outback. To some, it is a place that one would "never, never" want to go (despite this neat-sounding trip). To some of those who live there, it is a place one would never, never want to leave.

There are many parallels between Australia's Outback and the American Southwest, especially the Colorado Plateau. Most of the local populations live on the margins of the region, and until recent decades many parts remained unexplored by people of European descent. To others it has been home for thousands of years. The lands are ancient, each part revealing a fascinating geological story. And so it is that I refer to the Colorado Plateau as America's Never Never.

When we last left off the story we had explored Antelope Canyon, a deep slot canyon near Page Arizona. It was late by the time we finished our tour so the sun had set long before we arrived at our next campsite at Navajo National Monument on the lands of the Navajo people.

It was hard to get a sense of the country we had reached in the dark of the night, but when the sun rose I set out across the plateau to get a view of the countryside. Navajo National Monument is actually composed of three different units several miles apart: Inscription House, Keet Seel, and our location, Betatakin. Each of the units protects the ruins of an ancient people, the Ancestral Puebloans (once called the Anasazi). They were the "ancient ones" who lived on this land before the Navajo arrived hundreds of years ago. They abandoned the region 700 years ago; Their descendents live on the Hopi Reservation and the pueblos of New Mexico.

The land is unique. It is a high plateau called the Shonto that reaches elevations of more than 7,000 feet, which is high enough to support a forest of juniper and pinyon pines. The cooler forested highland is a stark contrast to the mostly barren deserts that surround the uplift. The plateau exposes Triassic and Jurassic aged sedimentary rocks, primarily the Navajo Sandstone. The Navajo is a major scenery maker in the region, responsible for the incredible cliffs in such places as Zion and Capitol Reef National Parks. The main drainage of this part of the Shonto Plateau is Tsegi Canyon, a deep gorge with an intricate maze of side canyons. Alcoves in the deep canyons protect some of the most perfectly preserved cliff dwellings to be found anywhere.

The alcoves are especially striking. There are impermeable layers of shale and siltstone within the Kayenta formation which underlies the Navajo Sandstone. Groundwater seeps downward through the Navajo and then encounters an impermeable layer. The water is forced to flow sideways until it breaches the surface at the base of a Navajo cliff. The cement holding the sandstone together dissolves and an alcove begins to form. It gets larger as slabs fall from the arch-shaped cavern. The alcoves turned out to be ideal spots for constructing villages. They are dry, protected from the worst of the weather, often have seeps or springs as a secure water supply, and offer superb defensive positions.

Defense? From what or whom? The Ancestral Puebloans lived in the region for well over a thousand years, but did not build the defensible cliff dwellings until very close to the time of regional abandonment. It's ironic that the most iconic remains of their culture represented not the pinnacle of their success, but the harbinger of their doom. It has long been the subject of speculation as to why the Ancestral Puebloans left the Four Corners area (except for the Hopi who continue to live in the general area). The speculation centers on a horrific drought that gripped the region in the late 1200s. Persistent drought would have led to ongoing crop failures and soil loss (as wind blew away dry topsoil). Starvation would presumably have led in turn to raiding and warfare.

Anthropologists, archaeologists, and the descendants of the Ancestral Puebloans have differences of opinion as to the reasons for the abandonment, but drought and resource depletion must have played a role. The villages at Keet Seel and Betatakin (in the pictures above and below) look like their inhabitants simply walked away, and the buildings have persisted in their protective alcoves through the intervening centuries.

We like to think in our technological bubble that we are somehow immune from such problems, but the need for water and food is still fundamental, and we are once again seeing the story unfold in the Colorado Plateau region of persistent decades-long drought. The present drought has now lasted 14 years, not far off from the 25 year drought that forced the Ancestral Puebloans to leave. The big difference is that the population that depends on water from the Colorado River now numbers in the millions, not the thousands. We can draw water from elsewhere, but drought is gripping California as well. It is a worrisome time.

One cannot explore the villages of Navajo National Monument without taking a stiff hike and the presence of a ranger/guide (Inscription House is closed to all visitation), but a short trail winds across the plateau surface from the visitor center to an overlook hundreds of feet above Betatakin. The preservation of the village is truly astounding, given our sorry penchant for destruction of all things ancient. It's a fascinating place to visit.

Into the Great Unknown: In the Depths of Grand Canyon, There are Three More Grand Canyons...Checking out the Supergroup

It was now day six of my journey down the Colorado River through the Grand Canyon, a trip I've been calling Into the Great Unknown, in honor of John Wesley Powell and his crew, who first navigated the river in 1869. We had floated down 65 miles from Lee's Ferry, and had now worked our way through 4,000 feet of Paleozoic sedimentary rocks that told a story of transgressing seas, tropical reefs, the growth of mountain ranges in strange places, vast sand seas, and once again a transgressing sea. It is an incredible story encompassing 300 million years, but it turns out these layers are only a small part of the whole story of Grand Canyon.

On this day we reached the hidden depths of the canyon that reveal a sequence of rocks three times as thick as the Paleozoic section. These rocks record another 550 million years of history in the time prior to the Paleozoic Era.  The rocks are known collectively as the Grand Canyon Supergroup and they range in age from 1.25 billion years to 700 million years, part of the time period we call the Proterozoic Eon.

We set out from our camp at Carbon Creek and floated past exposures of the Dox Formation, which formed in river floodplains and coastal complexes. It is more than 1,000 feet thick.

Dark cliffs appeared on both sides of the river. We had reached the lava flows and intrusions of the Cardenas Lavas which were erupted just over a billion years ago on top of the Dox Formation.

How does one fit 12,000 feet of sediments and lava flows into the bottom 1,000 feet of the Grand Canyon? The rocks are tilted! In the picture below, the Tapeats Sandstone can be seen as a horizontal layer at the top of the cliff. Beneath the Tapeats are tilted layers of black Cardenas Lavas and reddish Dox Formation. The eroded surface that forms the boundary between the two sequences is called an angular unconformity. The next question might be "how did they get tilted?".

Moments later we had an answer: the rocks of the Grand Canyon Supergroup were tilted by major faults that formed when the North American continent was breaking away from Australia and Antarctica in latest Proterozoic time. We passed one of these major fault lines, the Butte Fault, near mile 66. The sedimentary layers have been dragged to a nearly vertical orientation (below).

The character of the canyon was changing once again (as I've mentioned previously, there is no single Grand Canyon; it was different every day and practically every hour). For nearly a week we had been in a deep gorge with vertical walls hundreds or thousands of feet high. Now the canyon was much wider and more open.

We saw one of the truly rare evidences of human activity from our vantage point on the river. In the picture below one can barely make out the Desert View Watchtower (just left of center on the rim). The tower is three or four stories high, and yet was barely visible among the high cliffs. The tower is one of the main tourist centers on the South Rim of Grand Canyon National Park. I thought of how many times I had stood at Desert View looking down and wondering what it would be like to float down the river. This week it was finally happening, after a wait of forty years!

We reached Tanner Rapid and pulled over to hike up to some petroglyphs on boulders that had tumbled down the slopes of the Dox Sandstone. The openness of the canyon was refreshingly different.

To many people, the canyon was not the "Great Unknown". It was their home.

I always wonder what was being said by the individuals who chipped these messages in the rock.

It was a hot day. I had the outdoor lead for the thermometer in the river and the indoor lead on the boat. 113 degrees! Yikes. We decided against a hike at lunch near Tanner for lack of shade. We went a bit farther down the river where we needed to scout Unkar Rapid.

The Unkar Delta was one of the largest settled areas along the Colorado River in Grand Canyon. The sites were occupied between 850 and 1200 AD, some 350 years! They were partly excavated in the late 1960s, and the park service has constructed a trail that visits many of the sites.

Despite the heat, I hiked the whole loop. It was hard to think of this barren area as a possible "home", but it was probable that the inhabitants moved higher up in the canyon in the hottest times of year (and conversely this would be far more comfortable a home in winter).

Meanwhile, the oarsmen were scouting Unkar Rapids (6 on a scale of 10). It looked rather ferocious, but these rafters know their craft, and the run was splashy and fun.

Ron in the other raft was pointing towards the North Rim. I looked up and saw for just a moment the arch of Angel's Window, a popular viewpoint on the Walhalla Plateau.

I've stood near Angel's Window many times, looking at the Colorado River framed in the arch (the picture below is from a trip in 2012). Look at the size of the people on the arch and consider how small they are from a river point of view! When Coronado's troops saw the Grand Canyon for the first time in 1540, they thought the river was only six feet across. They were only off by 200-300 feet! The Grand Canyon can have a huge effect on one's sense of scale.

We pulled into our camp at Upper Nevills. The river was wide and calm at the campsite, and there were nice rock ledges that made cleaning and laundry convenient. I also for the first time decided to actually test my personal flotation device and did a dunk in the river. At 52-53 degrees, the river was COLD! I commented in my journal that I was glad I hadn't been involuntarily dunked in the river yet (literary note: this sentence is an example of foreshadowing...).

Tomorrow was a big day. We were facing some of the monster rapids, including Hance (8), Sockdolager (7), and Grapevine (7). I hit the sack.

From Out of the Depths of the Grand Canyon...

Nankoweap granaries, built by the Ancestral Puebloans around 900 years ago

Well, I did it. I made the trip I've waited most of my life to do, and I had an incredible experience. The Grand Canyon is almost indescribable, although you know I'll try to do so over the next few weeks and months. There were something like 160 rapids, and I rafted 158 of them. I wasn't so lucky on the other two, and that will be a couple of the stories. I was unhurt, though, and today I am as happy as can be that I've finally been through the heart of the Grandest Canyon.

Redwall Cavern in Marble Canyon, Grand Canyon National Park

The Abandoned Lands...A Journey Through the Colorado Plateau: The Rise and Fall of Empires, Part 2

We had reached the heart of the Abandoned Lands, having done the journey somewhat in reverse, by first finding the descendants of the Ancestral Puebloans at their present day homes along the Rio Grande and other nearby regions (Acoma and Taos), and then checking out one of their 'intermediate' settlements at Bandelier National Monument. We had also seen one of their recently abandoned pueblos at Pecos.

But now we had crossed the desert and had reached Chaco Culture National Historical Park, which for around 300 years constituted the center of the Ancestral Puebloan world. We had arrived on the evening of the summer solstice, and had experienced a kind of eerie night and beautiful solstice sunrise.

How do we know that Chaco was so important to the Ancestral Puebloans? Their descendants, for one, say so in their oral traditions. And then there is the sheer size of the complex at Chaco Canyon, something like fourteen major villages ("Great Houses") within a few square miles. There is the evidence of advance planning, as many of the building complexes are carefully aligned with the cardinal directions and astronomical and seasonal markers. And then there are the roads...

Source: http://en.wikipedia.org/wiki/File:San_Juan_Basin_Prehistoric_Roads.jpg

 

We have heard the expression that "all roads lead to Rome", but we don't usually associate roads with Native Americans. But if you look at the map above you can see that a system of straight roads led directly to the Chaco Canyon complex. The Puebloans cleared rocks and added berms in places, and when the roads encountered cliffs or other barriers, they built stairs (below). I don't think OSHA was consulted on this stairwell...

Below is a stretch of the Great North Road. The roads weren't for wheeled vehicles of course, but were instead pathways for pilgrims, and efficient routes for transporting supplies and materials, especially wood beams. The nearest forests were 40-50 miles away.

 And another set of steps...

The Great Houses also reveal their spiritual or political importance in the fact that they were not designed primarily for habitation. The complexes are huge, some with 700 rooms and originally standing four stories high, but not so many hearths for warmth, for instance (and winters are cold in this region despite the desert conditions). Wandering among the ruins, one can see the thinking of the planners and architects: this place was meant to engender a feeling of overwhelming power and awe in the visitor.

The major complexes at Chaco were built between around 850-1150 AD, and it is remarkable how well they have survived the elements for the last 900 years. These are not cliff dwellings, protected in alcoves and the like. They are out in the open and exposed to intense weathering from wind, ice and rain. Unlike many other unfortunate archaeological sites, Chaco Canyon today is in a remote location, so the buildings have not suffered as much the trepidations from vandals and early would-be "archaeologists". In addition, most of the complexes have never been excavated, and are thus protected beneath their own debris (having the walls exposed at the excavated ruins leads to rapid degradation; it is a cost associated with making a place interesting and educational to visit while trying to preserve the evidence of the past).

They had geological engineers in their midst, these Puebloans. Pueblo Bonito, the Great House we are touring in these pictures today, was tucked up against a cliff of the Cliff House Sandstone. The Cliff House Sandstone sits on top of a much weaker layer, the Menefee formation, and is often undercut by erosion so that large blocks of the sandstone will often tumble down the slopes into Chaco Canyon.

It was clear to the builders that a huge rock threatened the edge of the pueblo (we called the rock "Threatening Rock" in a fit of creativity). The Puebloans built a berm to try and stabilize the rock, and apparently they did a good job. It didn't collapse until 1941 (the pieces can be seen in the picture above).

Pueblo Bonito is a fascinating place to explore, being the most completely excavated of the Great Houses. It had 700 rooms, two great kivas, and a high outer wall that enclosed an area of two acres. The level of sophistication is such that no buildings in North America exceeded this complex in size until the 19th century.

It was uncomfortably hot wandering around the ruins on this particular day, which got me thinking about water at Chaco Canyon. There isn't any to speak of. The climate is very dry with an average rainfall of 8 or 9 inches. What did the Ancestral Puebloans do for water?

In the picture below, we can see the south wall of the complex...

One of the Great Kivas at Pueblo Bonito can be seen below. It was big enough that I couldn't fit the whole thing in a single shot. It took some major engineering to keep a ceiling over this space.

The wood used in the door beams and floors of the complex provided the means of dating the Chaco Canyon structures. Dendrochronology could be used to establish when the trees were cut down. The trees were not at all local; they came from mountains 50-70 miles away. Estimates are that 200,000 mature conifers were used in the construction of the Great Houses.

This has been just one of the fourteen Great Houses at Chaco Canyon. I'll look at a few others and deal with the question of why they were abandoned in the next post...and throw in some geology, too.