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: Migrations, Calderas, and the Middle of the Story at Bandelier

My ancestors migrated. My great-grandfather's family was struggling to survive in the hill country of Kentucky, and with eight hungry children it wasn't easy. In the early 1900s they heard of farmlands and jobs in the Indian Territories north of Texas, the land that would soon be known as Oklahoma. They arrived, and although life was still hard, the family thrived.

After a generation, things began to change. There were a series of drought years, and the Great Depression added to a hard existence. There were the horrific dust storms, and in 1936 a tornado destroyed my grandfather's house, nearly killing him. But they hung on. They found jobs here and there, and always kept up a vegetable garden in their spare hours. They canned food when they could, and sold fresh vegetables off their wagon in town.

World War II was well underway when the family made a momentous decision. Relatives in California said that things were better out there, and that they should move west. The family sold most of their things, loaded up their car, drove through New Mexico, and got as far as Kingman, Arizona before their transmission failed. The repairs took six days and nearly all their money, but they labored on, traveling at night through the Mojave Desert and arriving the next morning in the Central Valley. We're still here several generations later.

Reading about the journeys of the Ancestral Puebloans made me think of my own family history. How intolerable did things have to become to cause a person, a family or a village to give up and move on? Something happened on the Colorado Plateau that caused entire societies to abandon the region. Many of the displaced groups headed southeast, presumably because of stories of more secure water supplies along with relatively unpopulated but arable lands near the Rio Grande River.

I've been telling the story backwards. I've had a couple of posts about the pueblos at Acoma, Pecos and Taos where the Ancestral Puebloans ended up and are thriving today. Today's post is about the middle of their journey, a place that was a population center for several centuries, but which was ultimately abandoned as the inhabitants moved down into the Rio Grande Valley. It is Frijoles Creek on the flanks of the Jemez Caldera which is preserved as part of Bandelier National Monument.

Bandelier has one of the stranger geologic settings of any archaeological park. The walls of the canyon are full of holes, not unlike a giant chunk of swiss cheese. We had seen a place like this on the first morning of our trip, at Hole in the Wall in the Mojave Desert. It resulted from differential erosion of a thick layer of rhyolite tuff. Here at Bandelier, the origin is the same, only from rocks much younger.

It was less than 1.2 million years ago that a vast eruption blanketed the region with a thick layer of hot ash, more than a hundred cubic miles worth. The source of this incredible explosion was a vent to the northwest. The erosion was so huge that the crust collapsed into a vast hole 12 miles across. The Jemez (or Valles) Caldera, as it is called, is one of the three active supervolcanoes in the United States. Yellowstone is the best known, with the California's Long Valley Caldera at Mammoth Lakes being the other. The ash at Bandelier is soft, but readily forms cliffs, so the inhabitants of Frijoles Canyon took the holes and enlarged many of them into rooms. Other rooms were built out from the cliffs, reinforced by logs embedded in the ash.

People have lived in Frijoles Canyon off and on for several thousand years, but the majority of the structures and villages were constructed after 1150 AD, when the Colorado Plateau was beginning to be depopulated. The villages at Bandelier were abandoned by the middle of the 1500s as the Puebloans moved closer to the Rio Grande River. Their descendants live on in the present-day pueblos.

The canyon is a fascinating place to explore. The large village of Tyuonyi is easily accessed from the visitor center. A huge excavated kiva can be viewed next to the village. The most spectacular ruins are those which are scattered along the base of the cliffs for a long distance up the canyon. A trail winds up and through the ruins, and ladders provide access to some of the cavern openings.

The trail provides a look at details of the rhyolite tuff as well. In shaded corners, plants have gained a roothold...

 ...including this tree that I can barely believe was alive.

 If you suffer from acrophobia, I will definitely not recommend the trail to the Alcove House (below).

It is 140 feet above the canyon, and is reached by a series of ladders. If you don't mind the exposure, the payoff is pretty amazing. The Alcove House was a dwelling with 22 rooms and a kiva, which has been reconstructed. The alcove provides a marvelous view up the canyon (check out the first picture in this post).

Bandelier was ravaged by two disastrous fires in 2000 and 2011. The most recent fire burned 60% of the park. Although the visitor center area did not burn, the area upstream did, and the slopes have lost the vegetation that would prevent flashfloods from developing. The floods have wreaked havoc on  the park, with trails and bridges being repeatedly washed out, while parking and picnic areas have been inundated. Private cars are currently being parked just outside the park and shuttles provide access. The park has a campground on the plateau above the canyon (including group sites).

I've written about Bandelier a few times before when I was working on "Time Beyond Imagining". Check out this post, and this one.

Monday Geo-picture: Bandelier National Monument

Monday geo-pictures (for busy geo-bloggers; what a great idea, Georneys)...here is another scene from the southwest, this time at Bandelier National Monument. The monument preserves ancient pueblo cliff dwellings and villages which are fascinating in and of themselves, but the scene is made even more interesting because of the geological setting. Bandelier sits on the flank of the gigantic Jemez (Valles) caldera, which covered the region with red-hot ash around 1.15 million years ago. The pueblo people found the ash cliffs easier to excavate than sandstone, and numerous holes pockmark the cliffs representing the rear rooms of the dwellings.

The kiva in this photo required a 140 foot climb to reach (mostly on ladders). It takes some imagination to understand the effort undertaken to live in such an inaccessible place.

Time Beyond Imagining - Where did the Ancient Enemy Go?

Bandelier National Monument on the flanks of the Jemez (Valles) Caldera is a fascinating place to observe Pleistocene geology, being the site of a massive rhyolite eruption only 1.15 million years ago (back to geologic time instead of human time; so much for yesterday's post on deep time...). Subsequent erosion carved canyons into the slopes of the volcanic edifice that later provided arable environments when humans arrived in the region within the last 10,000 years. Their construction of these dwellings in Frijoles Canyon provides a piece to an interesting puzzle.

Part of the mystique of the Colorado Plateau has to do with the disappearance of the Anasazi People ("Ancient Enemy" in the Navajo language. I know that name is out of vogue, but bear with me on this). A number of reasons have been advanced to explain why essentially the entire region was depopulated about the end of the 1200's. They point to a disastrous 25-year drought, soil and resource depletion, religious influences, invasions and warfare. For years it was standard procedure to promote this deep mystery of "where did all the people go, and why?" I haven't read the book in years, but even Louis L'Amour got in on it with Haunted Mesa, where I guess they disappeared into some different dimension or something (I didn't think it was one of his better efforts...).

Not being an anthropologist, I am perfectly satisfied with the idea of the stress of a drought as the root cause of the migrations out of the region. Making a living on the plateau has always been a dicey proposition, and it still is today. Big cities like Phoenix, Salt Lake City, Albuquerque and Las Vegas flank the plateau country, but few towns thrive in the midst: Flagstaff, Moab, Farmington, Cortez, and a few others, totaling a few hundred thousand people at most. Water is a limiting factor, and even today with all the technology we have for pulling water up and out of rivers and from underground, most towns on the plateau barely have enough. Water for use by the 4 million yearly tourists at Grand Canyon is captured at a spring on Bright Angel Creek deep in the canyon, and pumped up 5,000 feet to both rims.

There is, in fact, a tremendous amount of water available on the Colorado Plateau. The Colorado River offers something like 10-15 million acre-feet each year, even in the dry ones. But where is the river? Across most of the plateau, the Colorado flows through deep canyons, far from any kind of arable lands. Today, to make use of the water, we've had to construct giant monstrosities of dams and reservoirs to capture the water, and a huge network of canals and pipelines to distribute the water to where we have chosen for it to go. That technology wasn't available 700 years ago.

If you were a community of people living on the edge, depending on the yearly rains that simply weren't coming, the choice boils down to migrating elsewhere or starving. A prolonged drought would have serious consequences: crops would fail, hunger would be widespread, soil erosion would commence, and in an such an environment, one could understand that a fight for survival might mean a fight with others for limited resources. Religious beliefs would certainly play a part, since the gods would be presumed to be angry, and they would need to be placated to bring back the rain.

As to the "where" part of the question, that is somewhat less of a mystery. They moved to where dependable water supplies could be found. For some communities, these were the mesas that nowadays form the Hopi Reservation. Some of the towns there have been occupied continuously since the 1100's. Others headed south and east into the Rio Grande River country where two dozen different puebloan groups continue to live today. The Acoma and Taos pueblos have been continuously occupied for around 1,000 years, and the village at Bandelier was constructed about 1150 AD.

The term "Anasazi", mentioned before as meaning "ancient enemies" by the Navajo, has no precise meaning. The haunts of the people now called "Ancestral Puebloans" on the Colorado Plateau had been abandoned by the time the Navajo people arrived in the region.

Does the story of the Ancestral Pueblo people on the Colorado Plateau have any relevance to our society today? Ya think? The southwestern part of the United States is in the midst of a historically unprecedented drought that is probably influenced in large part by global warming. There are serious concerns that Lake Powell and Lake Mead could conceivably go dry in a decade. The effects are being felt at Bandelier as well, although ecologists don't see the effects as all bad. Just the same, millions of people depend on the Colorado River. If the modeling is correct, we have some serious choices to make concerning water use in this arid region.

The first picture of the day shows Frijoles Canyon in Bandelier with the rim of the Valles Caldera on the horizon. The ruins in the main canyon include the unique cliff houses (second picture) carved directly out of the softer parts of the rhyolite (the linear pattern of holes is where timbers were inserted to hold up floors and roofs). Harder chunks of rhyolite were used to make the bricks that form the buildings in the village called Tyuonyi on the main nature trail at the monument (third picture).

School begins tomorrow! If blogs become a bit more irregular, you'll know why...

Time Almost Not Beyond Imagining: Recent Volcanism on the Colorado Plateau and Deep Time

1.15 million years ago, a massive explosion shook the New Mexico landscape, and some sixty cubic miles of ash shot into the atmosphere in a catastrophic rhyolite caldera eruption. The collapse of the magma chamber produced the Valles (Jemez) Caldera. Some of the ash traveled as far east as Iowa, but most of it was dumped on the flanks of the volcano in layers hundreds of feet thick. It was so hot upon landing that the material fused back together into a solid light-colored rock called welded tuff. Smaller eruptions followed, the most recent around 50,000 years ago. Erosion has been eating away at the margins of the caldera, forming a number of deep canyons (see this map of the caldera). One of these canyons is called Frijoles, the "Canyon of the Beans".

Tucked away in Frijoles Canyon one of the more interesting national monuments in the park system: Bandelier. It preserves the remains of an Ancestral Pueblo village that was built nearby and sometimes right into the welded tuff generated by the Jemez Caldera eruption. It is a fascinating place to explore. Although humans had passed through the region for portions of the previous 10,000 years, the village was built around 1150 AD and abandoned about 1600 AD.

A couple of divergent thoughts crossed my mind when I was considering a post on Bandelier National Monument. They had to do with deep time, and the wanderings of people. Wanderings takes up the next post. Here, I wanted to provide a bit of perspective about geologic time.

A thousand years seems a long time to the casual tourist wandering through these very ancient dwellings. We can feel a connection to these people sometimes as we look at the drawings they made on the rock, or the personal improvements in the living spaces in the rock rooms of the village built into the cliff. And yet they seem far removed by time. The year 1600 seems impossibly distant to our daily lives.

Still, there were (and actually still are) people in my life who were personally acquainted with Civil War veterans. And those veterans would have known people whose lives reached into the 1700's. Two or three degrees of separation...it isn't that far back is it? We can perhaps visualize that kind of time if we work at it.

But 1.15 million years? Even though we have actually covered 2 billion years in this series on the Colorado Plateau, I sometimes find even a million years difficult to comprehend. One million. One thousand thousand. The entire history of Bandelier's village, from construction to abandonment to tourist destination could be repeated 1,000 times to reach the time when the volcano exploded. And beyond that: the history would have to be repeated 65,000 times to reach the time when the dinosaurs disappeared, and more than 200,000 to reach the time when dinosaurs first appeared. And they appeared relatively late in Earth's history.

Deep time is one of the four great discoveries that mark the biggest advances of my science, that of geology: the others were the principles of uniformitarianism, evolution, and plate tectonics. The first two are largely credited to one man, James Hutton, and evolution is credited to Alfred Wallace and Charles Darwin, although others were involved. Plate tectonics was the discovery of dozens, even hundreds of researchers, although Alfred Wegener is given credit for kick-starting the idea though sheer stubbornness (I guess this should give the Alfreds of the world some hope!).

Bandelier National Monument is a fascinating and scenic place to wander. The top photo is of a kiva set in a high alcove in the upper canyon. Getting to it requires an acrophobic climb up some high ladders and narrow trails. The rocks of the canyon walls are full of holes caused by cavernous weathering of the relatively soft rock. Along the canyon floor, the Puebloans scraped and scooped out the rock to make their living spaces larger and more comfortable. I will have some more photos of the ruins in my next post. Camping and other facilities (mostly built by the CCC in the 1930's) are available.