4 Ancestral Puebloan Engineering Marvels

The Ancestral Puebloan people were an enigmatic agrarian culture in the ancient American Southwest. This culture did not vanish but remains in their current-day descendants, which include the Hopi, Zuni, and several other communities along the Rio Grande. This mighty river runs through Colorado, New Mexico, and acts as a border between Texas and Mexico. Researchers recognize eight distinct cultural phases of the Ancestral Pueblo culture, with major changes in settlement behavior occurring during the Pueblo I period. During the 8th century CE, the Ancestral Pueblo peoples shifted from hunter-gatherer subsistence to agrarian activity. Communities grew, creating a need for increased housing, food, and water. Using natural resources like sandstone, clay, and lumber, the Ancestral Pueblo culture developed monumental structures using stone masonry and calculated engineering. These engineers also created water reservoirs and irrigation channels to meet the water requirements of the people and their crops.

Several of the engineering marvels accomplished by the ancestral Puebloans are still standing after over 1,000 years and are recognized as World Heritage Sites by UNESCO. These UNESCO World Heritage Sites include Mesa Verde, Chaco Canyon, Taos Pueblo, and Aztec Ruins National Monument.

During the 12th century CE, the Ancestral Pueblo people constructed monumental stone masonry dwellings in the cliffs of the Colorado Plateau. They utilized spaces under overhanging cliffs, which sheltered the structures from wind and rain while providing a defensive advantage against their enemies. The dwellings varied in size, ranging from single-room constructions to multi-storied villages with over 100 rooms. The Ancestral Pueblo farmed on the mesa tops above, making the most of the semi-arid climate of the region. By the 14th century CE, they had abandoned these cliff dwellings.

The Architecture of Mesa Verde

Known as pueblos, these apartment-like cliff dwellings had a defensive advantage, as the only ingress and egress was a ladder that could be pulled up quickly in the event of an attack. The stone walls of the structures provided a strong defense against enemy weapons, and strategically placed window openings allowed for the Ancestral Pueblo warriors to return fire.

While studying the Sun Temple, a ceremonial structure on top of a mesa within the Mesa Verde complex, archaeologists discovered that the site was constructed using geometric principles like Pythagorean 3:4:5 triangles and right angles. Another remarkable discovery was a standard unit of measurement of around 30 cm, which is very close to the modern standard unit of measurement of 1 ft, which comes to 30.5 cm.

During the Pueblo I cultural phase, the Ancestral Pueblo people engineered water reservoirs at the base of canyons that could hold as much as 40,000 gallons. These reservoirs were filled by both groundwater and runoff from the surrounding canyons and were sealed with clay to prevent leaking. According to hydrologists, some modern engineers still use this technique to prevent the leaching of wastewater.

The Ancestral Pueblo engineers also built canals and ditches to channel water into the reservoirs, using height and gravity to their advantage. Over time, they would adjust the height of the channels to match the reservoirs, as the accumulation of sediment would raise the reservoirs’ height over time. This precise engineering is recognized today, with the American Society of Civil Engineering honoring the reservoirs of Mesa Verde as a Historic Civil Engineering Landmark.

2. Chaco Canyon

With an arid climate and challenging landscape, one would think the San Juan Basin of New Mexico would be an unlikely location for a thriving ancient society. This region has an annual rainfall of just 8 inches, long winters, and a limited growing season. Despite these environmental challenges, the Ancestral Pueblo people built monumental settlements and lived in the Chaco Canyon for over 300 years.

The Ancestral Pueblo also constructed roads to connect the great houses of Chaco Canyon, going beyond the canyon to connect to outlying settlements. They managed to farm corn, beans, and squash using terraced crops and prudent irrigation systems. There is also evidence that some resources and food supplies were imported using the constructed roads. As the region was limited in resources, trade was vital to the survival of this large community.

During the 9th century CE, the Ancestral Pueblo people began constructing large settlements along Chaco Canyon. These monumental structures are known as great houses, and were designed for residential, public, and official uses. Great houses were constructed using precise masonry and had as many as 800 rooms and five levels. Included were room blocks intended as living spaces and storage rooms and subterranean kivas for ceremonial or political gatherings. In front of the kivas and room blocks were plazas, open spaces used for day-to-day activities and gatherings.

The Roads of Chaco Canyon

The Ancestral Pueblo constructed well-engineered roads to connect communities within Chaco Canyon, and Chaco Canyon to other outlying settlements. These roads were about 27 feet wide, roads in Chaco were well-engineered, about 27 feet wide, and linked Chaco Canyon to other sites. Engineers leveled ground for the roads and, in some areas, built stone or earthen curbs.

Signal fire stations were placed along these roads, allowing for fast communication along Chaco Canyon and to its sister sites. These roads also facilitated trade that extended as far as Mexico and the Gulf of California.

The Hydrology of Chaco Canyon

During archaeological work, researchers have uncovered evidence of several canal systems and water diversion from different sources by stone masonry gates. These canals led to reservoirs, gridded fields, and terraced crops, making the most of their limited water supply.

The Ancestral Pueblo also utilized the cliffs north of the great houses to collect water, constructing reservoirs and channels to collect and divert rainwater down to small agricultural fields.

The Taos Valley of northern New Mexico provided resources that supported the Ancestral Puebloan peoples for many centuries. Bordered by the Rio Grande and the Taos mountains, life-sustaining water and construction materials were within reach of the Ancestral Pueblo people going back to the 10th century CE

Established during the 13th century CE, Taos Pueblo quickly became an important trade and communication hub between tribes. The Ancestral Pueblo went on to host impressive trade fairs in the fall seasons following major harvests. Descendants of the Ancestral Pueblo still live at Taos Pueblo today, maintaining the traditional adobe structures, which have survived for seven centuries.

The Architecture of Taos Pueblo

Recognized as the best-preserved pueblo located north of the modern-day border between the United States and Mexico, Taos Pueblo includes adobe houses built close together and with five or six vertical stories. The adobe houses were built in a step-back style, with the roofs of each level also acting as the floors and terraces for the above stories. The homes became narrower as they rose, having 70 cm thick adobe walls at the structure base, narrowing to 35 cm at the top of the house.

The local clay used in construction contains mica, which lends a glittering appearance to the buildings, especially when in the sunlight. It is said that the Spanish explorers thought they had discovered the “Cities of Gold” when they first saw Taos Pueblo. There is no doubt that this settlement was a sight to behold, with its glittering walls and wall surrounding the pueblo.

Located in the modern-day city of Aztec, New Mexico, the settlement known as Aztec Ruins was built during the 12th century CE by the Ancestral Pueblo culture. These structures got their name from 18th-century American settlers who mistakenly understood them to be of Aztec origin. Now a national monument, the Aztec Ruins site is situated on the west bank of the Animas River in northern New Mexico.

Many of the stone masonry buildings and kivas have been reconstructed, so visitors can visualize and understand the history of the Ancestral Pueblo people. The Aztec Ruins complex includes several multi-story residential great houses similar to those of Chaco Canyon. Each great house has a subterranean kiva used for gatherings, and Ancestral Pueblo engineers built roads to connect the great houses.

The Architecture of Aztec Ruins National Monument

While performing research, archaeologists discovered that the stone masonry structures were built using formal engineering and local resources. The structures and surrounding features suggest that the Ancestral Pueblo relied heavily on the nearby Animas River while respecting the power this water source yields. Archaeological excavations have uncovered earth pedestals used to raise structures above potential flooding, as well as earthen berms surrounding the structures. The latter may have been intended as windbreaks and channels to deter floodwater.

Many archaeologists find it remarkable that these early settlers not only recognized the potentially destructive power of the river, but also successfully protected the structures against these dangers it. The Animas River still floods occasionally, causing damage to modern neighborhoods along its banks.