The Abandoned Lands...A Journey Through the Colorado Plateau: Surviving in the Great Rift

I've been doing this journey through the Abandoned Lands sort of backward...the places we've been exploring, like Acoma, and today's location in Taos aren't abandoned at all. And we aren't even on the Colorado Plateau at this point. We are actually traveling through the Rio Grande Rift, a giant tear in the crust of the Earth that extends from southern Colorado to Texas and Mexico.

It's backwards because what I have been calling the abandoned land, the Colorado Plateau, was deserted by the Ancestral Pueblo people in the 1200s. The pueblos we are visiting, like Acoma, Cochiti, and Taos, are the places to which the Ancestral Pueblans migrated, and still live today. So we're telling the end of the story before the beginning and the middle. But we will be back on the Colorado Plateau soon enough, and sometimes it helps to know how the story ends before we deal with the beginning. It helps us to understand why things are the way they are today.

Taos Pueblo is one of the single most photographed buildings in North America. Along with Acoma and Old Oraibi, it is among the oldest continuously inhabited villages in the country. It has a spectacular setting, tucked on a high plain between the Sangre de Cristo Mountains and the Rio Grande River. It's not on the Rio Grande River, like most of the other New Mexican pueblos. It's not hard to see why...

The process of forming a rift valley involves tens of thousands of feet of faulting and thinning of the crust. The release of pressure on the underlying mantle allows partial melting and the formation of basaltic lavas that can follow the fault lines to the surface, forming voluminous lava flows. In the vicinity of Taos, the lavas blocked the Rio Grande, but rivers aren't intimidated by lava flows; they cut right through. The Rio Grande Gorge near Taos is no place for a village. There isn't enough flat land for building or growing.

So Taos Pueblo was built at the foot of the Sangre de Cristo Mountains, the southern extension of the Rocky Mountains. A creek flows from Blue Lake, high on the slopes of Wheeler Peak, and flows down into the Rio Grande. Called the Rio Pueblo de Taos or Red Willow Creek, it provided dependable water for the village. That's it in the picture below. The lake and the creek are sacred to the people of Taos Pueblo.

One of the most emblematic battles that ever took place at Taos Pueblo involved the federal government, but didn't involve guns and bows. Instead, it involved lawyers and senators. The creation story of the Taos people points to Blue Lake as their place of origin. It was part of their history and spiritual journey. But in 1906 the federal government took over administration of the lake, adding it to Carson National Forest. The people of Taos expected to have access to their sacred lands, but the forest service had different ideas, opening the region to "multiple-use": ranching, mining and recreation. The pueblo began a campaign to get their lands back. It took a shamefully long time, but in 1970 President Nixon signed legislation returning Blue Lake to the Taos Pueblo.

Things were not always peaceful in the pueblo at Taos. One of the clues is the San Geronimo mission church which is probably the second most photographed building in the country. It was built all the way back in...1850. 1850? That's not so long ago in a town with a 900 year history.

Pecos Pueblo, the subject of our last post, was at a geographical choke-point, and as such was directly involved in wars and battles for much of their existence. The ongoing conflicts took their toll and in 1838 Pecos was abandoned. Taos was farther to the north and could pick and choose their battles. They were major players in the 1680 Pueblo Revolt, and resisted the return of the Spaniards twelve years later. Things were apparently mostly peaceful for the next century or so, but things changed with the Mexican-American War in 1846. The United States laid claim to New Mexico, and the Taos Pueblo resisted the new government, along with Mexican nationals living in nearby Taos.

The battle did not go well for the defenders, and in the end a large number of them took refuge in the San Geronimo mission church behind a heavy wood door and thick adobe walls. The U.S. forces tried axes on the door and failed, so they rolled in a cannon. In a few hours the battle was over and around 150 people were dead. The ruins of the church still stand (below), surrounded by the Pueblo cemetery. The new San Geronimo church was built in a new location.

The Taos Pueblo is among the most conservative of the New Mexico pueblos, and around 150 people follow the traditional ways, living in the old village with no running water or electricity. It is a fascinating place to visit

Time Almost Not Beyond Imagining: Recent Volcanism on the Colorado Plateau Pt. 3

Top picture of the Valle Grande by Garry Hayes. Bottom image of the Valles Caldera courtesy of the New Mexico Bureau of Geology and Mineral Resources.

I will probably get a bit of geographical argument about today's geological feature, as it might not really be considered part of the Colorado Plateau, and more a part of the Rio Grande Rift, but it is on the plateau side of the rift, and on my field trips to the plateau, it is an important stop. So there you go. I've been moving towards wrapping up my long running series of posts on geological history of the Colorado Plateau, and we are into the last few million years of plateau history. At 6 million years, the final parts of the Colorado River system were established and the main carving of the Grand Canyon had begun. Volcanism began in the Flagstaff region, with numerous cinder cones, lava domes, and a stratovolcano forming the San Francisco Peaks Volcanic Field. Further to the east, the crust was stretching and breaking the crust to form the deep trough of the Rio Grande Rift. Like the peaks near Flagstaff, the faulting of the rift provided an avenue for magma to reach the surface. Unlike the Flagstaff area, the volcanism manifested itself in a totally different and violent way. This is the Valles (or Jemez) Caldera of New Mexico.

Valle Grande in the midst of the caldera is a beautiful serene high altitude prairie surrounded by and containing numerous forested lava domes reaching elevations as high as 11,000 feet. The grasslands fill a crater-like depression 12 miles in diameter. The peaceful scene belies a catastrophic origin.

As America's first national park, Yellowstone gets a lot of press, historically for all the geysers and bison and stuff, but more recently because of documentaries about "supervolcanoes" on various science-related cable channels. I'm sure the film-makers would never stoop to broadcasting sensational stories about impending eruptions that would destroy life across a broad swath of the continent, but somehow people have gotten that impression. Just the same, Yellowstone in modern times has developed a reputation as a spectacular example of an active rhyolite caldera. What is not so widely recognized is that the continental United States has at least three active caldera systems: Yellowstone, Long Valley in California (Mammoth Lakes), and the Valles Caldera in New Mexico. And a major eruption from any one of them would be a true catastrophe on par with a asteroid impact. The good news is that such eruptions are rare, with hundreds of thousands of years of volcanic quiescence between major events.

Eruptions have been taking place in the vicinity of Valles Caldera for six million years. A major caldera formed in an eruption about 1.5 million years ago (the Toledo caldera), and then the eruption of the Valles Caldera destroyed the older caldera and formed the present depression about 1.15 million years ago. It is hard to imagine the scale of such events. The last eruption in the lower 48 states, that of Mt. St. Helens in 1980, produced about a quarter of a cubic mile of ash and lava. It killed four dozen people and devastated 150 square miles. One of the most famous eruptions in modern history, at Krakatoa in 1883, was the equivalent of 20 St. Helens eruptions, producing 5 cubic miles of ash. The eruption of the Valles Caldera produced just more than 60 cubic miles: the equivalent of 250 St. Helens. With so much material blown out from the magma chamber, the ground above could not remain stable, and it collapsed into the void. Ash from the eruption covered a multi state region; near the volcano it was so hot that as it landed it hardened into a solid rock, welded tuff.

In the millennia that followed, magma refilled the chamber and the center of the caldera rose several thousand feet. Smaller eruptions produced a number of lava domes, the most recent around 50-60,000 years ago, but the volcano is not dead. Magma still simmers deep in the crust under the caldera. Valles is now considered an ideal of example of a resurgent caldera.

During World War II, physicists first caused a nuclear chain reaction in Chicago but prudence dictated designing the atomic bomb in an isolated location. They chose the flank of Valles Caldera, and the Los Alamos National Laboratory was built on a potentially active volcano. Research continues there today, although the level of secrecy is somewhat less than it was; you can drive through town without being challenged by armed guards, although you may get irretrievably lost if you make a wrong turn on the confusing streets.

The caldera was a private ranch, but in recent years was given to the federal government and is now managed as a national preserve, which is kind of like a national park, but is supposed to be economically self-sustaining. Two other geologically significant parks are found on the flanks of the caldera: Bandelier National Monument, and Kasha-Katuwe Tent Rocks National Monument. They will be covered in subsequent posts.