Thursday, February 23, 2017

South Mesa

Great Kiva of Casa Rinconada
4 miles loop, 500 feet elevation gain
Difficulty: Easy-moderate, a short segment of rock scrambling necessary
Access: Poor dirt road to Chaco Culture NHP; Chaco Culture NHP entrance fee required, self-issue backcountry permit required

South Mesa is perhaps the least frequented of all the backcountry trails in New Mexico's Chaco Culture National Historical Park, which preserves the landscape at the heart of the Ancestral Pueblo civilization in the American Southwest. As Chaco Canyon is already a park that's a bit off the beaten path, South Mesa sees very few hikers. This hike has fewer archaeologically important sites than the nearby hikes to Penasco Blanco, Pueblo Alto, and Pueblo Bonito and Chetro Ketl, but it has the best views of the San Juan Basin of any hike in the park and offers close up looks at an unexcavated Chaco great house and the largest kiva in Chaco Canyon. Besides visiting the great house of Tsin Kletsin and the villages and great kiva of Casa Rinconada, the hike also passes through the more traditional Southwestern scenery in the box canyons along the trail.

There's a short stretch of scrambling on this hike in which you must climb through a crevice between two rocks. Most hikers in reasonable shape and have some rock scrambling experience will find this segment of the hike to be doable.

If you plan to hike this trail, I advise that you pick up the Backcountry Trail Guide at the Chaco Culture NHP visitor center, which gives detailed descriptions of the sites of archaeological interest along this hike as well as on the Pueblo Alto, Penasco Blanco, and Wijiji Trails; it's well worth its $2 price.

I hiked to South Mesa during the second day of my two day stay at Chaco Canyon. The park is a three hour drive from Albuquerque; the easiest way to reach it is to take US 550 northwest from Bernalillo, turning left at Road 7900 just past the Red Mesa gas stop a few miles before reaching Nageezi. Signs directed me to the park from US 550, taking me first down a nice paved road (Road 7900) and then down a decent gravel road (Road 7950) that then turned into a bumpy, washboarded dirt road that required driving through a wash. During dry weather, the road is probably doable for most vehicles, though it is not an easy drive; if water in the wash is high, the park may be inaccessible. The road became paved again at the park entrance; I turned right for the Park Loop Road just past the visitor center and followed the one-way road past the turnoffs for Pueblo Bonito and Penasco Blanco to the parking lot for Casa Rinconada. I parked here, filled out a self-issue backcountry permit, and started my hike.

Two trails branch out from the parking lot, different branches of a short loop hike through Casa Rinconada. I started by taking the trail to the left, which led to a number of former villages inhabited by the Ancestral Pueblo people. Unlike the other famous archaeological sites in Chaco Canyon, Casa Rinconada is not a great house: this site consists of a few villages and a massive great kiva. The great kiva lies along the return trip; on my way out, I checked out the villages. One of the most easily apparent features of these villages was that their walls were constructed to the same degree of sturdiness as the walls of the great houses: comparatively, these walls were quite thin. While contemporary scholarship on Chaco Canyon holds that the great houses of the canyon had relatively small populations and did not serve as cities, the canyon population of the Ancestral Pueblo is still estimated to have been between three and ten thousand, mostly in villages such as the ones at Casa Rinconada.

One of the villages at Casa Rinconada
Casa Rinconada
Each of the three villages contained a number of rectangular rooms; each also contained kivas. At one of the sites, it appeared that perhaps three layers of kivas had been built atop each other over time.

The third village lay at the foot of the south wall of the canyon. At this village, the South Mesa Trail branched off from the Casa Rinconada Trail; I left the wide path through Casa Rinconada and followed the South Mesa Trail as it immediately began an uphill climb. After making an initial switchback, the trail arrived at the foot of a rock wall; the trail followed a narrow crevice between two rocks to surmount this obstacle. This section required some rock scrambling; the space in the crevice is quite small so I'm not sure that everyone can make it through easily.

Scramble through rock crevice
After climbing through the crevice, the trail made another switchbacks and came to the top of a layer of sandstone. From this vantage point, I could see much of Chaco Canyon and many of the great houses in the canyon. The villages and the great kiva of Casa Rinconada were visible close by and I could see the sprawling complexes at Pueblo Bonito, Chetro Ketl, and Pueblo del Arroyo on the north side of the canyon. The walls of New Alto were visible atop the north rim of the canyon and even Kin Kletso and Casa Chiquita were faintly distinguishable from the canyon's sandstone walls.

Casa Rinconada great kiva, Pueblo Bonito, and New Alto from South Mesa
From here on, the remainder of the ascent was fairly gentle. The trail headed south, gradually climbing in elevation through the saltbrush desert covering the mesa. Views of the canyon to the north constantly improved, with views that at one point stretched as far as Penasco Blanco on West Mesa, meaning that every Chaco great house save Hungo Pavi, Una Vida, and Wijiji were in the viewshed of this hike. As I climbed higher up the mesa, I entered a landscape dotted with junipers, one of the few places in the park with any trees. At one point, I had a particularly nice view down a small box canyon cut into South Mesa down into the main trunk of Chaco Canyon.

Box canyon on the north side of South Mesa
Soon, the trail entered a flat desert landscape of saltbrush, cacti, and Mormon tea. Gazing out in all directions, I could see the Chuskas, Jemez, and snowy La Plata Mountains on three horizons. Tsin Kletsin came into view, resting atop what seemed to be the highest point on the mesa.

Tsin Kletsin
A mile and a half from the trailhead, I came to Tsin Kletsin. Tsin Kletsin is one of the smaller great houses, with only 70 rooms and three kivas. Like many of the other great houses, Tsin Kletsin is built on an elevated mound. The site remains largely buried by the desert, with just a few McElmo style walls of large sandstone brick masonry marking its presence on South Mesa.

Tsin Kletsin
The view of the Sacred Landscape of the Ancestral Puebloans from Tsin Kletsin is as impressive, if not more so, than the great house itself. Much of the San Juan Basin is visible from here: the La Plata Mountains, part of Colorado's San Juan Mountains, make up the snowy ramparts of the northern horizon. These mountains lie even further north than Mesa Verde and likely formed the northern reaches of Chaco influence. The great house of New Alto was visible in the same direction as the La Plata Mountains. To the west were the Chuska and Carrizo Mountains, which lay on Navajo land in the state of Arizona; these mountains would have separated Chaco's influence from that of the Ancestral Pueblo culture at Canyon de Chelly. To the northwest, the very tip of the spire of Shiprock poked above the horizon: Shiprock is a massive monadnock, a volcanic remnant that soars out of the flat desert of the Four Corners. The Continental Divide, and thus the eastern bound of the San Juan Basin, lay between Chaco and the Jemez Mountains, which were visible on the eastern skyline.

La Plata Mountains in the distance, New Alto faintly visible in the foreground
The Ancestral Puebloans likely took advantage of the extraordinary viewshed from Tsin Kletsin, using the great house as a signaling post. Archaeologists have suggested that a multistory kiva at Tsin Kletsin may have been used for sending fire or smoke signals to great houses many miles away; it's possible that messages could have been relayed through this method from great house to great house, allowing nearly instanteous communication between Chaco and Ancestral Puebloan settlements as far away as Chimney Rock in Colorado. Tsin Kletsin's location was chosen in part to fall on a perfect meridian with Pueblo Bonito and Pueblo Alto, part of the obsession with north-south alignments in the Ancestral Pueblo culture.

Leaving Tsin Kletsin, I chose to follow the long route, 2.5 mile route back to make a loop, heading left at the trail intersection with the South Mesa Trail. The trail began to descend gradually through the saltbrush top of the mesa and came to some beautiful views of the vast expanse of the San Juan Basin to the south as the angle of descent on the mesa steepened. I also enjoyed views of the colorful sandstone cliffs along the south side of West Mesa.

San Juan Basin
Soon, the trail came to the top of a wide box canyon. Here, the trail followed a Navajo sheepherder path as it descended from the top of the mesa to the gap separating the main body of South Mesa from the rocky fin that bound the box canyon to the west. The trail was not always well defined here, following cairns rather than an established path. Views of the San Juan Basin and both South and West Mesa were excellent throughout this segment of trail.

Box canyon on the west side of South Mesa
From the gap, the trail made a sharp switchback and dropped down to the canyon floor, exiting the box canyon from its mouth to the north. The box canyon portion of the hike was particularly scenic: sandstone cliffs hemmed in the canyon, with pretty alcoves formed by overhanging sandstone on the sides of South Mesa.

Once out of the box canyon, the single track trail from Tsin Kletsin joined a wide dirt road leading through South Gap back into Chaco Canyon. This dirt road parallels the roads that the Ancestral Puebloans built through South Gap from Pueblo Bonito. Current archaeological interpretations of Chaco Canyon's role as a regional ceremonial center might have meant that pilgrims to Chaco Canyon would have walked this same route through South Gap en route to the grandest great houses at Pueblo Bonito and Chetro Ketl.

South Gap
As I passed through South Gap, I saw Pueblo del Arroyo in the canyon itself. The dirt road made a wide right turn around the northwest edge of South Mesa after I passed through South Gap. After making the turn, Pueblo Bonito came into sight across the Chaco Wash and the great kiva of Casa Rinconada, built on an elevated mound, rose directly in front of the trail, still a few hundred yards away. I continued on this wide dirt trail until it reached the base of the Casa Rinconada kiva and rejoined the Casa Rinconada Trail. I turned left at this junction and followed the Casa Rinconada Trail up to the edge of the kiva.

The great kiva of Casa Rinconada is the largest kiva in Chaco Canyon at about 20 meters in diameter. It's unique in that it stands alone from any great house: the canyon's other great kivas are part of larger complexes at Pueblo Bonito and Chetro Ketl. Kivas, which are still used as ceremonial structures today by the modern Pueblo peoples, likely filled a ceremonial role for the Ancestral Puebloans as well. This kiva could have fit as many as 400 people, all under a massive roof made of wood and earth. Huge T-shaped doors bookend the kiva, with stairs leading up from the subterranean kiva's ground floor up to the elevation of the mound outside. The kiva's excellent condition is due more to reconstruction efforts than to some miracle of preservation.

Great kiva of Casa Rinconada
After circling this huge structure and appreciating the engineering knowledge and manpower necessary to construct it, I finished the last section of the Casa Rinconada Trail to return to the parking lot.

Wednesday, February 22, 2017

Penasco Blanco

Penasco Blanco rises above Chaco Canyon
8 miles round trip, 250 feet elevation gain
Difficulty: Moderate; potentially difficult/dangerous crossing of Chaco Wash may make trail impassable
Access: Poor dirt road to Chaco Culture NHP; Chaco Culture NHP entrance fee required, self-issue backcountry permit required

Between the ninth and thirteenth centuries, New Mexico's Chaco Canyon was the heart of a civilization built by the Ancestral Pueblo people. On the floor of this sandstone canyon, the people of Chaco developed architectural and engineering techniques to build multistory masonry great houses spanning acres, recorded astronomical events on the canyon walls, and conducted trade with settlements throughout the Southwest and with cultures based as far away as Central America. While the great houses of Pueblo Bonito and Chetro Ketl are likely the best known and most impressive of the canyon's many archaeological sites, many more great houses in various states of excavation and a pictoral record carved by the Ancestral Pueblo can be found on the trail to Penasco Blanco, the longest backcountry hike in Chaco Culture National Historical Park. The trail visits four great houses: Pueblo del Arroyo, Kin Kletso, Casa Chiquita, and Penasco Blanco. Some of the highlights of this hike, though, are the pictographs and petroglyphs: the segment along the Petroglyph Trail visits the most extensive collection of rock art in the canyon and the trail passes by the Supernova Pictograph, a depiction of the 1054 formation of the Crab Nebula.

This trail is flat for most of the way, with all of the more difficult parts of the hike near its end. The hike can be difficult or dangerous and impassable if there is any water flowing in the Chaco Wash. Although the wash is dry for much of the year, rainstorms or snowmelt can create a temporary river and make access to Penasco Blanco inadvisable.

If you plan to hike this trail, I advise that you pick up the Backcountry Trail Guide at the Chaco Culture NHP visitor center, which gives detailed descriptions of the sites of archaeological interest along this hike as well as on the Pueblo Alto, South Mesa, and Wijiji Trails; it's well worth its $2 price.

I hiked to Penasco Blanco during the first of my two days at Chaco Canyon. The park is a three hour drive from Albuquerque; the easiest way to reach it is to take US 550 northwest from Bernalillo, turning left at Road 7900 just past the Red Mesa gas stop a few miles before reaching Nageezi. Signs directed me to the park from US 550, taking me first down a nice paved road (Road 7900) and then down a decent gravel road (Road 7950) that then turned into a bumpy, washboarded dirt road that required driving through a wash. During dry weather, the road is probably doable for most vehicles, though it is not an easy drive; if water in the wash is high, the park may be inaccessible. The road became paved again at the park entrance; I turned right for the Park Loop Road just past the visitor center and followed the one-way road out to the turnoff for the Pueblo Alto/Penasco Blanco Trailhead. Here, I turned right again and followed this spur road to the parking lot at its end.

I filled out a self-issue backcountry hiking permit before leaving the trailhead. Instead of heading directly off on the trail to Penasco Blanco, I chose to first visit Pueblo del Arroyo, a great house that lies right next to the trailhead parking area. A short gravel path led to the great house, then circled around and through the structure. Pueblo del Arroyo was built in sight of two other Chaco great houses, Pueblo Bonito and Kin Kletso, and had perhaps as many as 300 rooms, making it one of the larger great houses at Chaco. Its name translates to "village on the wash," which makes sense due to the great house's location adjacent to the Chaco Wash. Similar to Pueblo Bonito, the site has been fairly thoroughly excavated, meaning that much of the remaining structure is visible. Pueblo del Arroyo was built during the 11th century, well after the construction of Pueblo Bonito and Una Vida. If you're simply looking for a great house in decently well-preserved state with most features visible, you don't need to travel far from the trailhead: there are many more cleanly excavated kivas and rooms visible at Pueblo del Arroyo than at any other of the great houses along this hike.

Pueblo del Arroyo
After doing a walkthrough of Pueblo del Arroyo, I returned to the parking area and started down the wide road trail towards Kin Kletso. In a third of a mile, I came to Kin Kletso and did a quick walk around the structure. It's not possible to enter the great house of Kin Kletso, but some of the walls and elevated kivas remain in decent shape and can be seen from the boundary of the site. Additionally, the large sandstone blocks used in this McElmo masonry style building can be appreciated without a close-up approach. The name of the house means "yellow house" in the Navajo language.

Kin Kletso
At Kin Kletso, there is a fork between the Pueblo Alto and Penasco Blanco trails. I took the left fork that led along the valley floor towards Casa Chiquita and Penasco Blanco.The trail followed the base of the cliffs along the north side of the canyon, dipping briefly into an arroyo as it crossed a small wash, and passed a precariously balanced hoodoo on the north wall of the canyon.

Hoodoo along the trail
Just beyond the hoodoo, at the point where the trail left the side canyon and reentered the main canyon, I came to Casa Chiquita, about a mile from the trailhead. This small great house was largely unexcavated and didn't have many remaining features to explore. Like Kin Kletso, Casa Chiquita was built late during the period of Ancestral Pueblo habitation at Chaco: it was built during one of the most phases of construction at Chaco, which ended not too long before the canyon's great houses were abandoned altogether. It's likely that the great houses were built along the north side of the canyon to maximize the amount of solar energy received; Casa Chiquita is built rather precariously at the very foot of the cliffs along the north wall.

Casa Chiquita
Leaving Casa Chiquita, the trail dipped into another small arroyo before returning to the main canyon. From this part of the trail, I was able to see the walls of Penasco Blanco, the destination of the hike, rising on the rim of the south side of the canyon.

Penasco Blanco viewed from floor of Chaco Canyon
The path past Casa Chiquita followed a Navajo wagon road later improved by Richard Wetherill, an amateur archaeologist who spent his later years in Chaco Canyon excavating the ruins here after earlier discovering Cliff Palace at Mesa Verde. Wetherill's tendency to sell artifacts that he collected to collectors rather than preserving them for future scientific study was a contributing factor to Congress's decision to pass the 1906 Antiquites Act, which gave the president broad powers to immediately protect landscapes of historical or scientific significance through a national monument designation. In 1907, Teddy Roosevelt declared Chaco Canyon a national monument, giving a measure of federal protection to a critical piece of American heritage.

Although the Ancestral Puebloans built the great houses of Chaco, they were long gone by the time European American explorers arrived in the area. Instead, the Navajo, a nomadic people related to the Athabaskans of Canada, migrated into the region around the sixteenth century. Early European forays in the area usually included Navajo guides, who relayed to them Navajo names for the land and its people. Anasazi, which was the previously common academic name for Ancestral Puebloans, was a Navajo word that meant "ancestors of our enemies," referring to their more recent clashes with the modern Pueblo people. In the mid-1860s, it appeared for a while that the Navajo would also lose their homelands in this region: during the middle of the Civil War, Colonel Kit Carson launched a fierce scorched earth campaign against the Navajos to uproot them from their lands. When the Navajo chose to go into hiding rather than surrender to the United States, Carson rampaged through the Four Corners, burning Navajo villages and destroying whatever food supplies and agricultural fields he found. In the spring of 1864, the Navajo surrendered to Carson and were led on the Long Walk of the Navajo, a brutal forced march through the deserts of Arizona and New Mexico to internment camps at Bosque Redondo, on the Great Plains in eastern New Mexico.

Conditions at Bosque Redondo were horrid, with the Navajo held on the same land as hostile Comanche and Apache peoples. By 1868, conditions were bad enough that even the US government recognized that the situation was unsustainable, and the Navajo were allotted 3.5 million acres and allowed to return to their homeland. Through this traumatic experience was born a sense of Navajo identity, an identity strong enough that the Navajo Nation today holds over 16 million acres, more than any other of the United States' indigenuous peoples.

Half a mile past Casa Chiquita, the trail branched into two parallel paths, with the Petroglyph Trail leading off to the right. I followed the Petroglyph Trail, which closely stuck to the base of the north wall for the next half mile, providing close up looks at the most extensive collection of petroglyphs in Chaco Canyon. I referred frequently to the Chaco Culture NHP Backcountry Trail Guide (available at the visitor center) to identify and learn about the rock art along this portion of trail. Many of the petroglyphs were fading into the rock, subject to centuries of weathering and erosion. One remarkably preserved petroglyph lay on the underside of an overhanging rock 35 feet above the canyon floor and showed a kachina.

Ancestral Puebloan Petroglyph
Most of the deeply-etched petroglyphs were left by the Ancestral Puebloans, who built the great houses of Chaco Canyon. However, there were also plenty of rock art left by later inhabitants and visitors. A few Navajo petroglyphs depicting battles on horseback were lightly etched into the stone with thin lines, contrasting with the more clearly imprinted Puebloan designs. One section of wall appeared to have been appropriated by European settlers as a visitor's log: here, names have been carved on the wall in English, with dates attributing them to visitors during the late nineteenth and early twentieth centuries. Some Navajo petroglyphs carved more recently show the influence of European expansion into the Southwest: one petroglyph appears to show train tracks.

Ancestral Puebloan Petroglyphs
The Petroglyph Trail rejoined the Penasco Blanco Trail half a mile after it started. I continued forward towards Penasco Blanco, crossing through another small arroyo. From here, the trail left its position hugging the north wall of the canyon, venturing out into the center of the canyon. About three miles from the trailhead, the trail made a turn to the left and dropped down into the Chaco Wash. Here, the trail crossed the wash itself: your ability to continue on the hike will depend entirely on the conditions of the wash itself. The Chaco Wash flows only occasionally: it's usually dry, but summer thunderstorms or winter snowmelt can cause create temporary flow. As a National Park Service sign warns here, crossing the Chaco Wash when it is flowing can be very dangerous: if there's any water flowing, you should turn back. If you're unsure prior to your hike whether the wash will be flowing, you can check from any of the bridges across the wash on the loop road. Even if you're used to fording river elsewhere, it's important to understand that the principal danger of fording Chaco Wash comes from the sticky mud and the possibility of sinking into and becoming stuck in the mud.

Here's a case of not doing as I do: the wash had low flow when I came to it, so in spite of warnings, I decided to cross anyway. After establishing that the mud in the river was much too sticky for a wading ford of the wash, I chose to jump the creek instead, making it safely across. You should really, really not do this and instead just turn back if you see water flowing here.

Safely across the wash, I found myself at the base of the south wall of the canyon. The Supernova Pictograph lay high above me, painted on the bottom of an overhanging section of cliff that has protected it from the elements for nearly a millenium. On July 4, 1054, a new light appeared in the sky from the constellation Taurus. A dying star some 6500 light years from Earth had exited its stardom with a supernova, releasing an explosion of stellar material that lit up the night sky. The supernova was visible even during the daytime for 23 days and was visible in the night sky for about two years. Astronomers in Song Dynasty China and the Islamic Abbasid Caliphate, the world's most scientifically advanced civilizations at the time, made detailed note of this "guest star." The Crab Nebula, which is not visible by the naked eye, is a cloud of interstellar gas and dust that is the last reminder of that event.

Ancestral Puebloans would have seen this supernova light up the night sky as well. Archaeologists examining this pictograph have interpreted this pictograph as a record of that supernova, with the star and the crescent moon recording relative positions of the two celestial objects. The supernova occurred during the height of the Ancestral Pueblo civilization and would almost certainly have been noticed by a people who meticulously tracked the movements of the sun and the moon and built their great houses to align with the movement of heavenly bodies.

Supernova Pictograph
After passing the Supernova Pictograph, the trail began to head east along the south wall of the canyon and started climbing up the the multitiered sandstone benches. Networks of tiny caves and crevices had been eroded into the canyon's sandstone walls here, making for a landscape filled with interesting shapes.

Caves along the trail to Penasco Blanco
The trail made a sharp switchback and then became less defined than before, following cairns across the rocky benches and ledges on the south side of the canyon. After circling around a small box canyon, I finally climbed up to the flat grasslands atop West Mesa. Looking forward, I could see the many walls of Penasco Blanco; looking back, I had a view deep back through Chaco Canyon; I could spot Pueblo del Arroyo and Pueblo Bonito in the distance and the walls of New Alto rising on the north side of the canyon.

Chaco Canyon, Pueblo Bonito and Pueblo del Arroyo visible
Ahead lay the walls of Penasco Blanco, the westernmost of the great houses of Chaco Canyon. Although Penasco Blanco is largely unexcavated, there's much more to see here than at similarly unexcavated great houses such as Pueblo Alto or Tsin Kletsin: the unique round structure of Penasco Blanco was discernable as I walked around the site. Many parts of its walls remained standing and a section of standing wall included a fairly well-preserved door. As with Una Vida and Pueblo Bonito, the construction of Penasco Blanco spanned hundreds of years: work on the great house began in the tenth century and did not end until the zenith of Ancestral Puebloan civilization in the early tweflth century. This great house shares the beautiful, finely-pieced together masonry of Pueblo Bonito rather than the coarser, large-block McElmo masonry of Casa Chiquita and Kin Kletso. Penasco Blanco also lies on a straight line with both Una Vida and Pueblo Bonito: while Bonito is the largest and grandest of the great houses in Chaco Canyon, Una Vida and Penasco Blanco form bookends at either end of the canyon.

Penasco Blanco
I wandered around the site, checking out the wide circular plaza and the masonry at the doors and windows. I caught a first quarter moon rising above the walls on the west side of the house while walking the loop around the area.

Moonrise over Penasco Blanco
From the west side of Penasco Blanco, there was a sweeping view to the west of the Chaco Wash joining the Escavada Wash with the Chuksa Mountains far in the distance delineating the worlds of Chaco Canyon and Arizona's Canyon de Chelly.

View from Penasco Blanco
After surveying the landscape and studying the beautiful Penasco Blanco, I retraced my steps to the trailhead.

Monday, February 20, 2017

Pueblo Alto

Pueblo Bonito viewed from above
5.5 miles loop, 350 feet elevation gain
Difficulty: Moderate, multiple areas of rock scrambling necessary
Access: Poor dirt road to Chaco Culture NHP; Chaco Culture NHP entrance fee required, backcountry self-issue permit required

The meticulous architectural design of the Ancestral Puebloans of Chaco Canyon is nowhere more evident than when viewed from above. The geometric shapes of the great houses, the mazes of rooms and kivas, and the sheer size of the complexes is much more obvious from a bird's eye view. The Pueblo Alto loop skirts the north rim of Chaco Canyon above the two most celebrated Chaco great houses, Pueblo Bonito and Chetro Ketl, providing an astonishing view of the heart of this ancient civilization. Hikers who make it out to this corner of New Mexico for this loop will also get to visit the great houses of Kin Kletso, Pueblo Alto, and New Alto, and see a variety of alterations that the Ancestral Puebloans made to Chaco landscpe. The hike requires a few sections of rock scrambling and squeezing through narrow cracks in rock, and may be inappropriate for those uncomfortable with rock scrambling or heights. If you have time for only one backcountry hike at Chaco Canyon, make it this one; I consider this to be one of the best hikes covered on this blog.

For cultural and historical background on the great houses of Chaco Canyon, especially of the two great houses viewed from above on this hike, check out an earlier post on the short hike through Pueblo Bonito and Chetro Ketl. The Chaco Culture NHP visitor center sells a Backcountry Trail Guide that covers interesting features of this hike, as well as the South Mesa, Penasco Blanco, and Wijiji Trails, for just $2- it's a good investment to get more out of your hikes.

I hiked this trail early in the morning, leaving the campground before first light and arriving at the gate for the Park Loop Road at its opening time, 7 AM. Once the gate was opened, I proceeded down the one way road and turned right at the turnoff for Pueblo del Arroyo and backcountry hikes parking. I parked at the end of the spur road, filled out a self-issue backcountry permit at the trailhead, and started down the wide trail behind the gate. Chaco Culture NHP is in a fairly remote area of New Mexico; it's easiest to arrive at the park from Albuquerque via US 550. Detailed directions are on the Pueblo Bonito hike description.

The first 0.3 miles of the hike were along a flat, wide unpaved road that is also open to bicycles. At the end of the 0.3 miles, the trail came to Kin Kletso, which means "Yellow House" in the Navajo language. As the Ancestral Puebloans left no written record, the original names of the great houses of Chaco are unknown; all modern names are either in the Navajo language or Spanish. When I arrived at Kin Kletso, the walls of the house were bathed in sunrise light, giving them an almost unearthly glow.

Sunrise light on Kin Kletso
Unlike many of the other great houses at Chaco where it's possible to walk into the site, at Kin Kletso it was only possible to view the great house from the outside. Kin Kletso is notably built with McElmo phase masonry, a late Chaco style from the last period of construction in the canyon that used larger stones and lacked the finesse of some of the earlier masonry; it is similar in style to the masonry at Mesa Verde.

At Kin Kletso, I took the right fork, leaving the trail that continued down the valley for the trail that circled to the back of the great house. Behind Kin Kletso, I came to a second junction: here, the Pueblo Alto Trail broke off from the path around Kin Kletso and began climbing quickly up the base of the cliffs. I followed the Pueblo Alto Trail, scrambling at times as I ascended to the foot of sheer sandstone cliffs. Here, it seemed momentarily as if the trail disappeared: the, looking to my right, I saw the path run through a narrow crevice between two massive sandstone walls. I squeezed and scrambled through the crevice, taking a little over a minute to climb through the crack and reach the rim of the canyon.

Scrambling route to reach the top of the cliffs
The trail emerged on a sandstone bench, up an initial set of cliffs from the canyon floor but still a level down from the top of the canyon. There were good views of the canyon bathed in morning light from the rim and an especially good view of Kin Kletso's layout. From here, I could make out the rectangular shape of Kin Kletso and see into its elevated kivas in a way that I was unable to from the canyon floor.

Kin Kletso's elevated kivas viewed from above
From here on, the trail was marked by cairns as it followed the canyon's north rim, making it occasionally difficult to follow. The trail generally followed the canyon rim but often made detours around box canyons of varying sizes. The hike was mostly over exposed sandstone and areas of loose sand and soil. As the trail headed eastward, Pueblo del Arroyo came into view: this great house is situated right next to the Pueblo Alto trailhead and is one of the more impressive and thoroughly-excavated great houses after Pueblo Bonito and Chetro Ketl. From the rim here, I could see through South Gap, a cut between the South and West Mesas, to see all the way across the barren New Mexico desert to Hosta Butte, far to the south. The landscape was overwhelming quiet, the silence broken only by my own footsteeps and the howl of coyotes.

Pueblo del Arroyo and South Gap
Signs along the trail pointed out some of the interesting features along the trail: one sign atop a rock indicated that the rock below had shrimp burrows, trace fossils that date to the time of the sandstone's formation, when what is today New Mexico was once a shallow sea. This sedimentary geological history has also this part of New Mexico with layers of coal and pockets of oil and gas. Oil and gas development is steadily encroaching on the park and the narrative of the Chaco landscape: just days before my visit, the Bureau of Land Management greenlighted a $3 million oil and gas lease on land near the park.

Other signs marked a stone circle likely left by the Ancestral Pueblo and pecked basins carved into the sandstone that undoubtedly resulted from human activities. One sign indicated that I should have been able to see masonry terraces built by the Ancestral Puebloans, but despite looking everywhere I couldn't see anything that looked like artificial terraces.

A mile into the hike, I came to a four-way trail junction. Here, the Pueblo Bonito Overlook spur headed slightly downhill to a viewpoint, while the two halves of the Pueblo Alto loop split with the counterclockwise approach heading straight ahead and the clockwise approach that headed directly to Pueblo Alto branching off to the left. I took the right fork first and hiked a hundred meters slightly downhill to the Pueblo Bonito Overlook. The D-shaped layout of the great house was very apparent from this lofty viewpoint. The great house's two great kivas, wide plaza, and many smaller kivas and rooms could all be seen. At the time of its

Pueblo Bonito from the Pueblo Bonito Overlook
Returning to the junction, I decided to hike the trail counterclockwise, following the trail in the direction of the Chetro Ketl overlook. The trail went around a small box canyon and then stayed set back on a bench away from the canyon's ledge, with no views down into the canyon. The trail was at times hard to follow here, with chains of footprints often leading away from cairns. It's important to stay on trail; but at one point, while paying more attentions to the footprints before me rather than cairns, I found myself a few meters off trail at the edge of a cliff with a view down into Pueblo Bonito, where I was able to look down directly into the pueblo's many kivas.

Kivas and rooms of Pueblo Bonito
The next 0.6 miles of trail continued following the top of the bench, with few views down into the canyon. When the trail finally returned to the canyon rim, Chetro Ketl was visible below. This angle showcased the north wall of Chetro Ketl; I found a better angle after circling around a box canyon, from which I could see both the great kiva of Chetro Ketl and its interior tower kiva. The trail followed part of an ancient Chaco road while on the rim above Chetro Ketl, though it's not obvious to the untrained eye (me) how it was possible to tell the old road apart from the surrounding landscape. More easily noticeable were the remnants of a rock ramp that once led from the foot to the top of the canyon. The top and bottom of the ramp still remained at the head of the box canyon, but the middle of the ramp had collapsed in a pile of boulders at the base of the cliff.

Chetro Ketl viewed from above
A little further down the trail, the path made a sharp turn to the east and then climbed to the top of the mesa. Numerous spots here required a bit of scrambling, including a section where the trail passed through a narrow crack between two rocks. This part of the trail isn't for everyone, though most hikers who made it up through the crevice near Kin Kletso in the first place will probably be able to make it through here as well.

Scrambling route to the top of the mesa
Once atop the mesa, the trail made its way steadily northeast, generally following close to the rim of a box canyon. The views along this part of the trail were among some of the nicer views in Chaco Canyon.

Rincon along the trail
Once I reached the head of the rincon (box canyon), the trail made a turn and began to follow the western rim of the same canyon. From here, a sign marked a viewpoint where I looked across the rincon and saw a staircase made by the Chaco people. The Ancestral Pueblo built an extensive road network radiating out from Chaco; their roads were notably straight and often simply ran over obstacles rather than around them. In this particular case, the road out of this canyon led out by a staircase cut directly into the rock. These staircases are found at multiple locations throughout the canyon and can be seen from the main park road near Casa Rinconada, but the Pueblo Alto Trail is one of the better spots to see a staircase up close. The tendency of Chaco roads to run over obstacles suggested some ceremonial significance in the paths chosen: some of the paths line up exactly with cardinal directions. Use of these roads, typically constructed to widths of over 20 feet, remained practical as the Ancestral Pueblo did not transport items by wheeled vehicles or travel through the burden of domesticated animals.

Chacoan stairway
As the trail continued past the box canyon, it began a gentle climb towards the top of the flat grasslands. Looking back, I caught nice views down Chaco Canyon towards Fajada Gap and lonely Fajada Butte, home to Chaco's famous Sun Dagger Petroglyph, a spiral carved into the rock that serves as a marker for the summer and winter solstices and evidence of the advanced scientific knowledge of the Ancestral Puebloans.

Fajada Butte and Chaco Canyon
Reaching the top of the grasslands, I spotted the walls of New Alto rising off in the distance. For the next half mile, I walked through the flat high desert towards New Alto and Pueblo Alto, catching views along the way of the snowy Chuksa Mountains to the west and Hosta Butte and South Gap to the south.

New Alto, Chuksa Mountains in the distance
While New Alto's walls rose clearly above the surrounding landscape, the walls of the largely unexcavated Pueblo Alto were not immediately recognizable as a great house from a distance. Thus, I did not noticed Pueblo Alto until I was more or less right beside the site and could see some masonry sticking out of the ground. I followed the path through and around the Pueblo Alto site, which is for the most part unexcavated. Pueblo Alto is a fairly large great house with a large plaza on its south side. Compared to many of the other great houses, there's not too much to see here, although the pueblo is certainly still significant in Chaco. Pueblo Alto lies on a single meridian line with Pueblo Bonito and Tsin Kletsin on South Mesa, meaning that the three houses form a north-south line. Pueblo Alto was once a single-story great house with a small resident population that served some important ceremonial function: archaeologists have found very few hearths in the large structure, suggesting few permanent residents, but they have uncovered a remarkable amount of broken pottery in the midden (earthen pile) just east of the great house. This broken pottery is potentially from rituals involving breaking pots, mirroring customs still practiced by the modern Pueblo.

Pueblo Alto
Pueblo Alto formed the branch point for the road network heading north from Chaco. The Great North Road, a wide roadway built due north from Pueblo Alto, once stretched across the high desert for at least 40 miles and potentially reached as far as Salmon and Aztec near Farmington and Chimney Rock in Colorado. Over 400 miles of Chaco roads have been mapped; as many of these roads have more or less disappeared into the landscape, identifying them takes an extremely discerning eye. One method of identifying the roads is in changes in vegetation- soil differences between the roads and the rest of the desert leave straight lines of altered vegetation. Another is simply to identify the road traces from air: while satellites perform that job today, early attempts to map these roads included aerial surveillance by famed aviator Charles Lindbergh.

Gazing out over the landscape of the Great North Road from Pueblo Alto, I could see as far as the La Plata and San Juan Mountains to the north and the Jemez Mountains to the east. Huerfano Mesa's peaks poked above the desert to the northeast. Nestled between these mountains was the San Juan Basin, the large flat desert valley of the San Juan River that holds Chaco Canyon at its heart.

La Plata Mountains and the landscape of the Great North Road
Leaving Pueblo Alto, I came to a trail junction where the left fork continued the loop, leading back towards the Pueblo Bonito overlook, and the right fork headed towards New Alto. I visited New Alto to see this small great house with relatively intact walls. New Alto was built at a relatively late stage in Chaco history, around 1100; the canyon was abandoned not too long after the house was completed. New Alto showcases McElmo masonry with its large sandstone blocks in its walls. There are a number of windows and doors at New Alto that have not yet collapsed as well as a small kiva that is largely unexcavated. While New Alto may not have been as significant of a site as Pueblo Bonito, Chetro Ketl, or Pueblo Alto, the good state of preservation of its walls makes the site enjoyable to explore.

Unexcavated kiva at New Alto
Walls of New Alto
Leaving New Alto, I returned to the main trail, which turned and headed directly south for the next half mile, descending back down into an intermediate level of the canyon and passing more remnants of Chaco roads along the way. The trail completed the loop at the Pueblo Bonito Overlook; from there, I retraced my steps from that moring and returned to the parking area.

This hike's points of archaeological interest and the good views of the great houses make it an essential part to any Chaco Canyon trip. 

Saturday, February 18, 2017

Pueblo Bonito and Chetro Ketl

Pueblo Bonito
1 mile loop, 50 feet elevation gain
Difficulty: Easy
Access: Poor dirt road to Chaco Culture NHP; Chaco Culture NHP entrance fee required

In the remote reaches of the New Mexico high desert, on the flat floor of a sandstone canyon hours from the nearest cities or towns, lies the heart of one of the great and advanced civilizations of precontact America. Here, amongst the saltbrush and arroyos, stand the remnants of magnificent public houses acres in size and five stories tall; for centuries, this was the beating heart of the Ancestral Pueblo civilization, the political and cultural nexus for the tens of thousands of their people spread over what is today the Four Corners. Here lies one of the most forgotten wonders of our world: the grandest architectural statements north of Mexico, with apartment blocks, great kivas, and wide plazas built by a people with a deep knowledge of the sun and the stars. This is Chaco Canyon, one of the most undeniably significant archaeological sites in the country.

Of all the great houses of Chaco, Pueblo Bonito stands out due to its meticulous construction, its extraordinary collection of artifacts, its high degree of preservation, its beauty, and its size: at the time of its discovery, the footprint of this great house, built over three centuries starting around 850 AD, was larger than that of the US Capitol in Washington DC. Chetro Ketl is the second most impressive of the Chaco great houses, with a large great kiva and a collection of rooms surrounding large elevated kivas. This short, one mile hike visits both houses and provides the incredible experience of walking through Chacoan rooms in Pueblo Bonito; it is the undeniable highlight of any visit to this UNESCO World Heritage Site.

I visited Pueblo Bonito and Chetro Ketl on a trip out to Chaco Culture National Historical Park, which preserves all twelve great houses and countless villages and dwellings in Chaco Canyon. The park is a three hour drive from Albuquerque; the easiest way to reach it is to take US 550 northwest from Bernalillo, turning left at Road 7900 just past the Red Mesa gas stop a few miles before reaching Nageezi. Signs directed me to the park from US 550, taking me first down a nice paved road (Road 7900) and then down a decent gravel road (Road 7950) that then turned into a bumpy, washboarded dirt road that required driving through a wash. During dry weather, the road is probably doable for most vehicles, though it is not an easy drive; if water in the wash is high, the park may be inaccessible. The road became paved again at the park entrance; I turned right for the Park Loop Road just past the visitor center and followed the one-way road out to the Pueblo Bonito parking lot.

Visiting close to sunrise or sunset can give an opportunity to see spectacular colors on the great houses. However, it's important to note that the Park Loop Road closes at sunset and that this closure is strictly enforced by the National Park Service; visitors who remain in the area after sunset may be ticketed. I also recommend budgeting plenty of time, especially if you appreciate architectural detail or history; I spent about 100 minutes doing this hike and still felt rushed.

Two trails led away from the parking lot: the left fork towards Pueblo Bonito, the right fork towards Chetro Ketl. I took the right fork and first visited Chetro Ketl. The trail passed by the indistinct outer wall of the great house and entered the large central plaza. The first section of wall that I got to observe from the trail was also one of the most interesting: here, the south-facing wall was clearly built with either large windows or square columns; archaeologists consider this the only colonnade in Chaco Canyon. As columns are otherwise absent in Pueblo architecture but was a feature of Mesoamerican architecture, it's likely that the construction here was influenced by styles over a thousand miles to the southeast.

Colonnade at Chetro Ketl
The trail also offered a chance to look down into some deeply excavated rooms, which was effective at conveying the fact that Chetro Ketl must have been a multistory structure and that current ground level is probably above the ground level of Chetro Ketl during its period of use.

Continuing past the colonnade wall, the trail turned back into the central plaza and came to the great kiva of Chetro Ketl. This kiva is very large, second only to the kiva at Casa Rinconada in size at Chaco Canyon. Kivas were community gathering spaces that likely served ceremonial and religious functions. This particular great kiva looked particularly impressive, though the completeness of the kiva walls and interior suggested that this particular kiva must have been partially reconstructed.

Great Kiva of Chetro Ketl
Past the great kiva, the trail passed by a set of smaller kivas in Chetro Ketl's southeast corner, then wrapped around to follow the north wall of the house.

Construction of Chetro Ketl began around 990 AD, after hundred of years of human habitation in Chaco Canyon and a century and a half after construction began on Pueblo Bonito, and took most a century to complete. Chetro Ketl's footprint is the largest of any Chaco great house, although at three acres it is very similar in overall size to Pueblo Bonito. However, Chetro Ketl lacks the shear number of rooms built at Pueblo Bonito; there are about 400 rooms in Chetro Ketl, which was likely up to four stories tall. The lack of plentiful artifacts at Chetro Ketl and the relatively small amount of refuse generated suggest that despite its size, Chetro Ketl may not have been densely inhabited.

Theories regarding Chetro Ketl's role in the Chaco world mirror theories regarding the canyon's place in the Ancestral Pueblo civilization. Undoubtedly, Chetro Ketl and Pueblo Bonito wielded power and influence broadly recognized throughout the San Juan Basin. Archaeologists and anthropologists have offered theories as to whether that power was religious, political, or both; most park literature introduce Chetro Ketl and Pueblo Bonito as centers for pilgrimmage from the villages in the orbit of the Chaco culture. Artifacts collected in the great houses have been interpreted as having ritualistic value, based off knowledge of similar items used today by the modern Pueblo peoples. It's very likely that these great houses were endued with some religious significance. Chetro Ketl and Pueblo Bonito were also the center of a trade network: turquoise and corn cobs traced to locations throughout the San Juan Basin were excavated from these houses. Chaco-style ceramics were exported, as Chaco designs have been found throughout outlying Pueblo settlements. Although current interpretations of Chaco suggest that the great houses served a mainly ceremonial purpose, past anthropological interpretations have suggested that Chetro Ketl and Pueblo Bonito might have formed the hub of power in a Pueblo state encompassing the San Juan Basin. As the Ancestral Puebloans had no written language outside of their pictographs and petroglyphs, there's no written record from which to understand Chaco's role in their civilization.

The trail finished its tour of Chetro Ketl by following the long north wall of the great house, which offered glimpses through windows to see the many rooms and the tower kiva in the house's interior.

Chetro Ketl window
Tower kiva at Chetro Ketl
Leaving Chetro Ketl, I came to the Talus unit, a small pueblo built at the base of Chaco Canyon's north wall. This pueblo had a number of kivas and some reasonably well-preserved masonry.

I continued past the Talus unit on the Petroglyph Trail, which connects Chetro Ketl with Pueblo Bonito; this trail followed the base of the canyon wall, rather than returning to the parking area. In the next third of a mile, I walked at the foot of impressive sandstone cliffs, gazing up occasionally at precarious columns of rock that seemed like they might tumble any time. At eye level, the canyon walls were dotted with petroglyphs carved into the sandstone by the Pueblo people a millenium ago.

Petroglyphs along the cliff between Chetro Ketl and Pueblo Bonito
The Petroglyph Trail ended by joining the wide path circling around the northeast side of Pueblo Bonito. At this junction, I took the right fork, which made its way through a massive jumble of fallen boulders and came to a platform atop a large boulder overlooking Pueblo Bonito.

Standing atop the viewpoint and gazing out over the remains of Pueblo Bonito, I was overcome with awe: spread out before me was a maze of rooms, walls, kivas, and plazas constructed of extraordinary masonry. The site's name, given by a US military unit that surveyed the area in 1849 after the Mexican-American War, translates to beautiful town; this vastly understates the extraordinary nature of Bonito.

The outer walls of the northeastern part of Pueblo Bonito are destroyed, having been crushed by a rockfall in 1941 by the collapse of Threatening Rock, once part of the canyon's north walls.

Pueblo Bonito
Multiple excavations over a century, starting with those by homesteader and amateur archaeologist Richard Wetherill, have uncovered a wealth of artifacts at Pueblo Bonito. These finds suggested that the residents of the Pueblo were either extremely wealth or yielded enough religious or political power to collect goods traded from far away. Rooms at Bonito held turquoise from Cerrillos (near Santa Fe), macaw feathers from Mexico, and pottery with traces of chocolate, which could only have been imported from Central America.

Wetherill discovered the famous Cliff Palace of Mesa Verde before conducting his excavations at Pueblo Bonito. Wetherill had the unfortunate habit of selling many of the artifacts that he excavated as souvenirs, a practice he shared with Gustav Nordenskiold, a Swedish explorer who taught Wetherill excavation techniques at Mesa Verde and who sent crateloads of Pueblo artifacts off to Europe. The practices of Wetherill and Nordenskiold- only part of the late nineteenth-century American custom of looting Ancestral Puebloan sites- sparked Congress to pass the Antiquities Act in 1906, giving the president authority for swift, unilateral action to protect areas of historical or scientific significance. Chaco Canyon National Monument, the precursor to the current Chaco Culture NHP, was one of the first monuments established by Theodore Roosevelt under the authority granted to him by the Antiquities Act.

Wetherill also bestowed the name "Anasazi" upon the people who built the pueblos of Chaco and Mesa Verde. Although commonly used as an academic term for the good part of a century, the name Anasazi has recently been abandoned for the term Ancestral Puebloans; Anasazi, after all, is a Navajo word that means "ancestors of our enemies." Often introduced to these ancient pueblos by the Navajo, Wetherill adopted their unflattering name for the people who built these structures. The Navajo name in turn comes from the rocky relationship between the Navajo and modern Pueblo peoples. While the modern Pueblo peoples are descended from the ancestral Puebloans, the Navajo are latecomers, nomadic peoples related to the Dene of the Canadian Great Plains and Alaska who arrived in the Southwest around the 15th century; the Navajo settled into the abandoned homelands of the Pueblo people and occasionally came into conflict with the Pueblo people. While Chaco was built by the Ancestral Puebloans, it has been part of the landscape inhabited by the Navajo for the past few centuries; the Navajo Nation lies just west of the park. Archaeologist Stephen Lekson noted the antipathy between the Pueblo and the Navajo when recounting an attempt to include Native American input in the Chaco Project, the last large scale excavation at Chaco: Pueblo people tried to exclude Navajo from providing input on the future of sites that the Pueblo claimed as their heritage, while the Navajo refused to be excluded from discussions about sites that lay in what is now the Navajo homeland.

Outer walls of Pueblo Bonito
Pueblo Bonito is roughly shaped like the letter D, with the rounded section of the building pointed north. The trail circled around much of the tall, semicircular northern wall of the building before entering through a gap in the wall. These walls reach up to five stories tall, indicating that the multistory construction at Pueblo Bonito at least led to the construction of masonry structures with five floors. To support the load of five floors, many of the walls at Pueblo Bonito are extremely thick: in some spots, the base of the walls are up to four feet wide. The walls taper off in thickness higher up, with the masonry walls just a foot thick on the fifth story.

Pueblo Bonito
A short spur trail led through one of the oldest parts of the building. The construction of Pueblo Bonito began around 850 AD, around the same time as the great house of Una Vida up the canyon; this far precedes the construction of the other great houses at Chaco and elsewhere throughout the Pueblo world. Bonito was built in several phases: the rest of the great house is effectively extensions built on this initial structure. The masonry in this older corner is notably poor, requiring much more frequent use of mortar than other spots in the great house that exhibit superb masonry. The sandstone making up the walls of all of the Chaco great houses were chiseled off the sandstone walls of the canyon.

Continuing on the, the trail brought me into the huge central plaza at Chaco. Two great kivas here were smaller than the great kiva at Chetro Ketl but were still over 50 feet in diameter and could have held hundreds of people during the Golden Age of Chaco.

Great Kiva of Pueblo Bonito
From the plaza, one trail led directly out the south wall of the complex and back to the parking lot. I did not follow that trail, instead taking the trail that headed to the left, climbing up a few stairs to a walkway elevated between four medium-sized kivas. From here, the trail then dropped down to an entrance into one of the rooms.

The last stretch of the path through Pueblo Bonito involves walking through 12 rooms in the complex and is one of the highlights of the hike; however, it does require passing through low doors, meaning most people will have to duck or crawl to go between rooms.

Multistory construction of Pueblo Bonito
One of the more interesting aspects of the Pueblo Bonito rooms are the wooden beams that served to separate different floors. In Chaco architecture, ceilings are floors were made from spaced-out wide wooden beams known as vigas covered with densely packed latillas, or smaller wooden beams. All of Chaco's 800 or so rooms were built with this roof structure. In each room, it's possible to see the many layers of vigas, each indicating an additional floor of Pueblo Bonito. In one room, the vigas and latillas were left intact during excavation and form the only remaining publicly visible ceiling in Chaco today.

These wooden beams were critical in helping archaeologists date Pueblo Bonito. Using dendrochronology, archaeologists match up tree ring patterns from the wooden beams with a known tree ring record for the Southwest that reflects yearly fluctuations in climate. Dendrochronology was critical in first establishing that Bonito's age and was used to trace the fact that construction of the full great house took nearly 300 years.

Where did the Ancestral Puebloans source so many wooden beams in the middle of a desert canyon with just a handful of cottonwoods? The answer lies 50 miles west of the canyon: the forested Chuksa Mountain supplied up to 200,000 trees for construction of Chaco's great houses. To me, this is one of the most stunning aspects of Chaco civilization: in a society with no domesticated livestock, human laborers transported hundreds of thousands of ponderosa pine through the desert to this dry, remote canyon to build magnificent structures. It seems impossible to me that this could have accomplished without strong societal organization and a large population. Interestingly, Pueblo Bonito itself, despite its size, is not believed to have housed many residents: although early archaeologists estimated the pueblo to be a city of over a thousand residents, more recent analyses point to the lack of hearths in the building to argue that most rooms were likely not residential and that the population of Bonito itself may have been only around one hundred.

Even if Pueblo Bonito itself was not heavily residential, Chaco Canyon itself likely supported a population of thousands, if not ten thousand, scattered throughout small villages and unit pueblos in the canyon. Although climate differences and advanced irrigation techniques probably allowed Pueblo farmers to turn the valley floor into productive agricultural land, much of the food at Chaco was still imported, with corn coming from as far away as the Chuksa Mountains. Chaco's influence reached to at least two hundred other great houses and villages in the Southwest, including the Ancestral Puebloan cultures at Salmon, Aztec, Lowry Pueblo, and Chimney Rock. While the true nature of political connections between Chaco and these outlying pueblos is unclear, the collective population of these related cultures was at least 20,000-30,000; I personally still find it amazing, if hard to believe, that a civilization with a population of only 30,000- less than that the population of Charlottesville- could have provided the manpower and planning necessary to build the Chaco great houses.

Corner window at Pueblo Bonito
One of the last notable architectural features on the Chaco walking tour was a corner door, a unique door that opened simultaneously on four rooms. Corner doors are fairly rare in Chaco, but many of the existing corner doors were built as astronomical markers. The ancient culture at Chaco had a deep knowledge of astronomy, incorporating features of astronomical significance into their building plans.

In fact, Chaco came to my attention due to the astronomical knowledge of the Ancestral Puebloans: Carl Sagan introduced their scientific feats in his TV series Cosmos. The Ancestral Puebloans tracked the sun, moon, and stars carefully: the most famous of their astronomical markers is the Sun Dagger petroglyph on Fajada Butte, near the Chaco Culture NHP visitor center. There, light passing through slits between three rocks pass over the center of a spiral petroglyph only at noon on summer solstice.

By the early 13th century, the people of Chaco were beginning to leave. After reaching its heyday in the 12th century, the canyon was completely abandoned by the Ancestral Puebloans a century later. The causes of this migration are not completely clear, although theories include a move forced by drought or climate change and a retreat from violent clashes with newly arrived nomadic peoples. In either case, the people of the Chaco world dispersed in the 1200s, moving south and east to the Jemez Mountains, the Rio Grande valley, and the lands now held by the Zuni and Acoma Pueblos.

Some archaeologists have noted that this migration was not sudden: many great houses were boarded up before being abandoned, with windows and doors filled in. What happened to the high culture and civilization of the Golden Era at Chaco? Based on the walling off of doors with astronomical significance in Chaco and on fires set in some kivas at the time of abandonment, some anthropologists have speculated that perhaps changing climate or other conditions led to a backlash against the knowledge of the stars, ending that study in Chaco culture. Whatever the reason, Pueblo Bonito has now been abandoned for seven and a half centuries.

As the sun prepared to set, I said goodbye to the extraordinary Pueblo Bonito and followed the last two hundred meters of a wide gravel path back to my car.