Chaco Culture National Historical Park
Chaco Culture National Historical Park is a United States National Historical Park in the American Southwest hosting a large concentration of pre-Columbian indigenous ruins of pueblos. The park is located in northwestern New Mexico, between Albuquerque and Farmington, in a remote canyon cut by the Chaco Wash. Containing the most sweeping collection of ancient ruins north of Mexico, the park preserves one of the most important cultural and historical areas in the United States.
Between AD 900 and 1150, Chaco Canyon was a major cultural center for the Ancestral Puebloans. Chacoans quarried sandstone blocks and hauled timber from great distances, assembling fifteen major complexes that remained the largest buildings ever built in North America until the 19th century. Evidence of archaeoastronomy at Chaco has been proposed, with the "Sun Dagger" petroglyph at Fajada Butte a popular example. Many Chacoan buildings may have been aligned to capture the solar and lunar cycles, requiring generations of astronomical observations and centuries of skillfully coordinated construction. Climate change is thought to have led to the emigration of Chacoans and the eventual abandonment of the canyon, beginning with a fifty-year drought commencing in 1130.
A UNESCO World Heritage Site located in the arid and sparsely populated Four Corners region, the Chacoan cultural sites are fragile—concerns of erosion caused by tourists have led to the closure of Fajada Butte to the public. The sites are considered sacred ancestral homelands by the Hopi and Pueblo people, who maintain oral accounts of their historical migration from Chaco and their spiritual relationship to the land. Although park preservation efforts can conflict with native religious beliefs, tribal representatives work closely with the National Park Service to share their knowledge and respect the heritage of the Chacoan culture.
The park is on the Trails of the Ancients Byway, one of the designated New Mexico Scenic Byways.
Geography
Chaco Canyon lies within the San Juan Basin, atop the vast Colorado Plateau, surrounded by the Chuska Mountains to the west, the San Juan Mountains to the north, and the San Pedro Mountains to the east. Ancient Chacoans drew upon dense forests of oak, piñon, ponderosa pine, and juniper to obtain timber and other resources. The canyon itself, located within lowlands circumscribed by dune fields, ridges, and mountains, is aligned along a roughly northwest-to-southeast axis and is rimmed by flat massifs known as mesas. Large gaps between the southwestern cliff faces—side canyons known as rincons—were critical in funneling rain-bearing storms into the canyon and boosting local precipitation levels. The principal Chacoan complexes, such as Pueblo Bonito, Nuevo Alto, and Kin Kletso, have elevations of.The alluvial canyon floor slopes downward to the northwest at a gentle grade of ; it is bisected by the Chaco Wash, an arroyo that rarely has water. The canyon's main aquifers were too deep to be of use to ancient Chacoans: only several smaller and shallower sources supported the small springs that sustained them. Today, aside from occasional storm runoff coursing through arroyos, substantial surface water—springs, pools, wells—is virtually nonexistent.
Geology
After the Pangaean supercontinent sundered during the Cretaceous period, the region became part of a shifting transition zone between a shallow inland sea—the Western Interior Seaway—and a band of plains and low hills to the west. A sandy and swampy coastline oscillated east and west, alternately submerging and uncovering the area atop the present Colorado Plateau that Chaco Canyon now occupies.The Chaco Wash flowed across the upper strata of what is now the Chacra Mesa, cutting into it and gouging out a broad canyon over the course of millions of years. The mesa comprises sandstone and shale formations dating from the Late Cretaceous, which are of the Mesaverde Group. The canyon bottomlands were further eroded, exposing Menefee Shale bedrock; this was subsequently buried under roughly of sediment. The canyon and mesa lie within the "Chaco Core"—which is distinct from the wider Chaco Plateau, a flat region of grassland with infrequent stands of timber. As the Continental Divide is only east of the canyon, geological characteristics and different patterns of drainage differentiate these two regions both from each other and from the nearby Chaco Slope, the Gobernador Slope, and the Chuska Valley.
Climate
An arid region of high xeric scrubland and desert steppe, the canyon and wider basin average of rainfall annually; the park averages. Chaco Canyon lies on the leeward side of extensive mountain ranges to the south and west, resulting in a rainshadow effect that fosters the prevailing lack of moisture in the region. The region sees four distinct seasons. Rainfall is most likely between July and September, while May and June are the driest months. Orographic precipitation, which results from moisture wrung out of storm systems ascending the mountain ranges around Chaco Canyon, is responsible for most of the summer and winter precipitation, and rainfall increases with higher elevation.Chaco endures remarkable climatic extremes: temperatures range between, and may swing 60°F in a single day. The region averages fewer than 150frost-free days per year, and the local climate swings wildly from years of plentiful rainfall to prolonged drought. The heavy influence of the El Niño–Southern Oscillation contributes to the canyon's fickle climate.
Flora and fauna
Chacoan flora typifies that of North American high deserts: sagebrush and several species of cactus are interspersed with dry scrub forests of piñon and juniper, the latter primarily on the mesa tops. The canyon is far drier than other parts of New Mexico located at similar latitudes and elevations, and it lacks the temperate coniferous forests plentiful to the east. The prevailing sparseness of plants and wildlife was echoed in ancient times, when overpopulation, expanding cultivation, overhunting, habitat destruction, and drought may have led the Chacoans to strip the canyon of wild plants and game. It has been suggested that even during wet periods the canyon was able to sustain only 2,000 people.Among Chacoan mammals are the plentiful coyote ; mule deer, elk, and pronghorn also live within the canyon, although they are rarely encountered by visitors. Important smaller carnivores include bobcats, badgers, foxes, and two species of skunk. The park hosts abundant populations of rodents, including several prairie dog towns. Small colonies of bats are present during the summer. The local shortage of water means that relatively few bird species are present; these include roadrunners, large hawks, owls, vultures, and ravens, although they are less abundant in the canyon than in the wetter mountain ranges to the east. Sizeable populations of smaller birds, including warblers, sparrows, and house finches, are also common. Three species of hummingbirds are present: one is the tiny but highly pugnacious rufous hummingbird, which compete intensely with the more mild-tempered black-chinned hummingbirds for breeding habitat in shrubs or trees located near water. Prairie rattlesnakes are occasionally seen in the backcountry, although skinks and various other lizards are far more abundant.
History
Archaic–Early Basketmakers
The first people in the San Juan Basin were hunter-gatherers: the Archaic–Early Basketmaker people. These small bands descended from nomadic Clovis big-game hunters who arrived in the Southwest around 10,000 BC. More than 70 campsites from this period, carbon-dated to the period 7000–1500 BC and mostly consisting of stone chips and other leavings, were found in Atlatl Cave and elsewhere within Chaco Canyon, with at least one of the sites located on the canyon floor near an exposed arroyo. The Archaic–Early Basketmaker people were nomadic or semi-nomadic hunter-gatherers who over time began making baskets to store gathered plants. By the end of the period, some people cultivated food. Excavation of their campsites and rock shelters has revealed that they made tools, gathered wild plants, and killed and processed game. Slab-lined storage cists indicate a change from a wholly nomadic lifestyle.Ancestral Puebloans
By 900 BC, Archaic people lived at Atlatl Cave and similar sites.DNA evidence establishes the people of Picuris Pueblo once lived in Chaco Canyon. By AD 490, the descendants of those who lived in Chaco Canyon, of the Late Basketmaker II period, farmed lands around Shabik'eshchee Village and other pit-house settlements at Chaco.
A small population of Basketmakers remained in the Chaco Canyon area. The broad arc of their cultural elaboration culminated around 800, during the Pueblo I period, when they were building crescent-shaped stone complexes, each comprising four to five residential suites abutting subterranean kivas, large enclosed areas reserved for rites. Such structures characterize the Early Pueblo People. By 850, the Ancient Pueblo population had rapidly expanded: groups resided in larger, more densely populated pueblos. Strong evidence attests to a canyon-wide turquoise processing and trading industry dating from the tenth century. Around then, the first section of Pueblo Bonito was built: a curved row of 50 rooms near its present north wall. Archaeogenomic analysis of the mitochondria of nine skeletons from high-status graves in Pueblo Bonito determined that members of an elite matriline were interred here for approximately 330 years between 800 and 1130, suggesting continuity with the matrilineal succession practices of many Pueblo nations today.
The cohesive Chacoan system began unravelling around 1140, perhaps triggered by an extreme fifty-year drought that began in 1130; chronic climatic instability, including a series of severe droughts, again struck the region between 1250 and 1450. Poor water management led to arroyo cutting; deforestation was extensive and economically devastating: timber for construction had to be hauled instead from outlying mountain ranges such as the Chuska mountains, which are more than to the west. Outlying communities began to depopulate and, by the end of the century, the buildings in the central canyon had been neatly sealed and abandoned.
Some scholars suggest that violence and warfare, perhaps involving cannibalism, impelled the evacuations. Hints of such include dismembered bodies—dating from Chacoan times—found at two sites within the central canyon. Yet Chacoan complexes showed little evidence of being defended or defensively sited high on cliff faces or atop mesas. Only several minor sites at Chaco have evidence of the large-scale burning that would suggest enemy raids. Archaeological and cultural evidence leads scientists to believe people from this region migrated south, east, and west into the valleys and drainages of the Little Colorado River, the Rio Puerco, and the Rio Grande. Anthropologist Joseph Tainter deals at length with the structure and decline of Chaco civilization in his 1988 study The Collapse of Complex Societies.