Headed into the Back of Beyond (Again)

I had hoped to finish our blog journey through the most dangerous plate boundary, but there was just too little time between real-world trips. The next journey is taking me and nearly two dozen students on a trip through time, both geological and anthropological. Our combined geology and archaeology class is exploring the fascinating landscapes of the Ancestral Pueblo people and other groups of the southwestern United States.

Archaeologists learning geology, and geologists learning archaeology. It's a symbiotic educational relationship that enriches students of both disciplines. We've done this trip a number of times, and it seems to get better every time.

This summer equinox picture of Fajada Butte at Chaco Canyon is emblematic of our trip, as we see Cretaceous sedimentary rocks of the Mesa Verde Group making up the cliffs and slopes. In the foreground, a small ruin from the people who lived on this land for more than a thousand years as a distinct culture. They then abandoned the region and 700 years later, a different group of people started to build roads again, with an asphaltic covering material (and mechanical air conditioning in their dwellings).

And all of the students are willing to dabble a bit in biology as well, especially when the object of their attention is so colorful.

Geotripper is going to be hit and miss for the next few weeks. I look forward to sharing our adventures in a few weeks!

The Abandoned Lands...A Journey Through the Colorado Plateau: The Rise and Fall of Empires, Part 3

An empire ended...

We've been following a route through the Colorado Plateau through what I've been calling the Abandoned Lands. It is a journey through some spectacular geology, but it is a journey that reveals some illuminating anthropology as well. We started at the end of a long journey of a people as they found homes along the Rio Grande River and its tributaries (Acoma and Taos), and then explored the dwellings that formed the midpoint of their migration ( Bandelier National Monument). In the last post of the series we had reached their starting point, at Chaco Canyon in northwest New Mexico.

For three hundred years, Chaco Canyon was the spiritual and economic center of the Ancestral Pueblo Universe. And then it was abandoned. Not with an ultimate battle against more powerful invaders, but with a whimper, a decline that took a number of years. Buildings weren't burned down (for the most part), but were cleaned out and sometimes sealed. It was an abandonment driven by the inability of the land to provide enough in the way of basic needs: water, crops and lumber. 

There was little timber in the region to start with, but they used vast amounts of conifer trees that had been hauled fifty miles or more. As the pueblos grew and the need for wood increased, the Ancestral Puebloans constructed roads to facilitate the importation from distant forests.

Casa Rinconada with Cliff House Sandstone and slopes of Menefee Formation.

The region probably never allowed for much in the way of agricultural production. In the desert climate, crops were always a marginal proposition. The people of Chaco imported maize from far-flung locations over distances of twenty or thirty miles.

An unexcavated ruin at Pueblo del Arroyo partially exposed by gullying.

Water was  also a challenge. There were no permanent rivers, and few springs. The problem was made worse by poor treatment of the soils which led to gully development that lowered the area's water table. Crops could be imported and so could wood. Water was another matter.

An unexcavated ruin near Pueblo del Arroyo, with Cliff House Sandstone in the distance.

A fifty year drought began around 1130 AD. It was the beginning of the end. Some of the outlying villages were abandoned first, and as the drought deepened, the main Great Houses were left behind as well. The area became the domain of ghosts and lost spirits (if your imagination is imaginative enough to hear their whispers).

What can we learn? Probably not that much. I mostly think about metropolitan centers like Las Vegas and Phoenix which are totally dependent on the importation of water over distances of hundreds of miles. They depend on energy and food imports from hundreds or even thousands of miles away. We can say that modern technology will continue to support the resource needs of millions of people, but what happens when the petroleum stocks start to run low (despite high prices, worldwide production of oil has remained flat for 6-7 years). And we are in the midst of a disturbing drought that climate scientists think will be the norm for decades to come. Are we thinking about the kinds of choices that must be made?

In the last post we explored Pueblo Bonito, one of the most completely excavated ruins at Chaco. The pictures today are from Pueblo del Arroyo and Casa Rinconada, which have large sections still buried beneath the sand. Modern archaeology recognizes that methods of analysis will improve in future years, and as such we need to leave some of the sites undisturbed. It also provides to visitors like myself a sense of mystery. What still lies hidden???

Three kivas built over the centuries on top of each other.

An empire ended...

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.

The Abandoned Lands...A Journey Through the Colorado Plateau: The Cosmos and Mystery at Chaco

“ After sleeping through a hundred million centuries we have finally opened our eyes on a sumptuous planet, sparkling with color, bountiful with life. Within decades we must close our eyes again. Isn’t it a noble, an enlightened way of spending our brief time in the sun, to work at understanding the universe and how we have come to wake up in it? This is how I answer when I am asked—as I am surprisingly often—why I bother to get up in the mornings.”
― Richard Dawkins

Night is a special time...yet in normal life we tend to hold the night at bay, to drive it away with light, whether in our own rooms, or with the glow of vast cities, or with a fire if we are stuck in the back of beyond somewhere.

We keep the night at bay, and in doing so we shrink our existence to the size of the room, the city, or the ring of light around the fire. What are we scared of? I guess throughout human history there was plenty to be scared of...animal attacks, attacks by rival humans, getting lost, and in modern days, muggings. But when I am out in the Colorado Plateau, the embracing the darkness is one of the most special experiences I can have.

Our trip through the Abandoned Lands had been on the road for a week, and for a multitude of reasons, I was exhausted by the end of the day and had not really spent much time looking at the night-time sky. We arrived at Chaco Culture National Historical Park and I made a point of the exploring the darkness. I sat and watched the stars sweeping across the sky, and made a brief effort at capturing a bit of the night in a photo (above). I guess it was pretty late because only one tent in the camp was still lit up.

The ancients gazed at the sky and invented patterns. If you know your stars, you've probably already figured out the constellation that fills the center of the photo (you can click it for a larger view). People invented stories to go with the images and the stories involved heroes and legends and eventually gods. At some point the gods became more important than understanding the lights themselves, and the skies began to lose their significance.

In the case of the night-time sky, religious explanations settled matters for most people, and they longer had any other reason to look to the heavens, except to keep times and seasons. I look at the sky and I can still see Scorpio (I outlined it in the picture below if you don't know the constellations well), but because of science, I have a lot more to see. I've learned that each of those points of light is  star like our sun, and that most of the stars out there probably have planets. The cloudy dim light that we call the Milky Way is made of so many stars our eyes cannot distinguish them. Other points of light out there are other galaxies beyond our own, made up of billions of more stars.  And there are billions of galaxies. The vastness of the Universe is far beyond our comprehension, but we want to comprehend, so we try to invent new ways to explore. That's the magic to me of science. I don't know what the future will bring on our human journey, but I try to imagine sometimes how quaint our ideas of the cosmos will seem to whoever follows us.

On the other hand, there are places that unsettle me. There are plenty of mysteries right here on planet Earth, and the night-time brings out all kinds of journeys of the mind. You are allowed to camp among some of the ruins at Chaco Canyon, allowed to sleep among the ghosts of centuries past.

I don't think of ghosts in the sense of spooky spirits and the like, but more the echos of past lives left behind in the ruins adjacent to our campsite. I was looking at pictures of my long-gone grandparents the other day, and I felt the same spiritual echos. Lives were lived and some legacy exists of their brief existence, those of the Ancestral Puebloans in their ruins and artifacts, and my grandparents in an emulsion film on photographic paper.

We also hear echos of the past because everything we are is a legacy of those who preceded us. The DNA in our cells is a genetic road map that leads through our parents, our grandparents, and all who came before. Our responses to the environment we live in today were shaped by those who survived in the past.

But our responses are also influenced by something unique in all of human history: scientific knowledge. We now know the causes of diseases; we understand chemical reactions and the predictions made by physics; we know of the history of the Earth and the history of our species far beyond the stories handed down by our ancestors. We have an inking of our true place in the cosmos in a way that no humans have ever been able perceive it before. I am thankful to be living in a day and age when the sum total of all human knowledge is available to us in a book, a laptop or a smartphone.

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It was a moonless night in Chaco this year. In previous years I've wandered along the road outside camp in the moonlight with a camera, as you can see in the photo above. I've also walked in the darkness at White House Ruins in Canyon de Chelly National Monument (below). Spooky? Not really. Mysterious? Absolutely. In the darkness you aren't just visiting or touring, you are experiencing a place more fully, as one notices the sounds and odors more keenly. Your eyes may not be able to see things clearly, but the mind is able to construct things that might be there, or might not.

It was June 20th, the summer solstice, the point in the year when the days are longest and the sun is highest in the northern sky. Along with the vernal and autumnal equinox, the solstice was one of the more important days of the year to the Ancestral Puebloans. At Chaco Canyon there are petroglyphs that record these moments, most memorably the Sun Dagger (I would love to say that I've seen it and have pictures, but it is off limits, having already been damaged by too much visitation). It seemed to me that not only did I want to experience the night, but I wanted to see the sunrise as well.


Whatever demons may exist in the darkness, they are chased away by the light...

The rays of the solstice sun reached Fajada Butte, and presumably at this moment, the Sun Dagger was pointing to the center of the spiral petroglyph. Camp was beginning to stir and equipment was being packed. We were going to explore what seems to have been the center of Ancestral Puebloan existence for hundreds of years.

A night-time pop quiz for you if you've made it this far: what the phase of the moon right now???