Solving the mystery of the Chaco Canyon houses: Ancient people of New Mexico carried wood for 50 miles to build mini-city

Solving the mystery of the Chaco Canyon houses: Ancient people of New Mexico carried wood for 50 miles to build mini-city

  • Great houses of Chaco Canyon, New Mexico, were built in 850 to 1140AD
  • Land was largely treeless, but 240,000 trees were used in construction 
  • Researchers compared tree-ring growth patterns from 170 great house timbers with the tree-ring growth patterns of trees from nearby mountains
  • Study found most wood was transported 46 miles (75km) to ancient site

They are some of the largest pre-Columbian buildings in North America, but until now it has been a mystery how the great houses of Chaco Canyon were built between 850 and 1,140AD.

The ancient structures, made from stone and wood, occupy a nearly treeless landscape, sparking decades of curiosity about the origins of more than 240,000 trees used to build them.

But now experts have proof, in the form of tree rings, that the wood must have been carried around 46 miles (75km) from surrounding mountains.

The ancient structures of Chaco Canyon (shown) are made from stone and wood and occupy a nearly treeless landscape, sparking decades of curiosity about the origins of more than 240,000 trees used to build them

The ancient structures of Chaco Canyon (shown) are made from stone and wood and occupy a nearly treeless landscape, sparking decades of curiosity about the origins of more than 240,000 trees used to build them

The great houses, some of which are partially standing today, are located in the high desert landscape of New Mexico, where ancestors of Puebloan people called home centuries ago.

They covered an area of 4,633 square miles (12,000 square km) around in the San Juan Basin.

The massive masonry structures required a wealth of resources to erect, including an estimated 240,000 trees incorporated as roof beams, door and window lintels, and other building elements, according to a study published in the journal PNAS.

They are some of the largest pre-Columbian buildings in North America, but until now it has been a mystery how the great houses of Chaco Canyon were built between 850 to 1,140AD. An aerial view of Pueblo Bonito - the largest house, is pictured above

They are some of the largest pre-Columbian buildings in North America, but until now it has been a mystery how the great houses of Chaco Canyon were built between 850 to 1,140AD. An aerial view of Pueblo Bonito – the largest house, is pictured above

Experts have proved the wood must have been carried around 46 miles (75km) from surrounding mountains. This map shows the source locations for great house timbers. The size of the green dots are proportional to the percentage of beams sourced from the location

Experts have proved the wood must have been carried around 46 miles (75km) from surrounding mountains. This map shows the source locations for great house timbers. The size of the green dots are proportional to the percentage of beams sourced from the location

The study has not discussed how the trees would have been transported to the site to construct the houses. But the Ancient Pueblo Peoples quarried sandstone blocks too. A reconstruction of the site is shown

The study has not discussed how the trees would have been transported to the site to construct the houses. But the Ancient Pueblo Peoples quarried sandstone blocks too. A reconstruction of the site is shown

CHACO CANYON’S INCREDIBLE BUILDINGS

Chaco Canyon contains the most widespread collection of ancient ruins north of Mexico.

Between 900 and 1150AD it was a major centre for the Ancient Pueblo Peoples.

They quarried sandstone blocks and hauled timber for great distances, assembling fifteen major complexes that remained the largest buildings in North America until 19th century.

Until now, experts were unsure where the trees came from, but now believe most were from the Zunis to the Chuskas mountains.

It is not known why the people decided to build such huge houses in an area lacking resources close by, but it could have something to do with astronomy.

It’s thought many of the buildings were aligned to capture the solar and lunar cycles.

The settlement is thought to have been abandoned with he emigration of Chacoans at the onset of a 50-year drought from 1130.

The first excavators of the great houses in the early 20th century speculated that construction timbers were harvested locally, perhaps resulting in deforestation of the surrounding landscape.

But subsequent studies revealed the land was never rich in timber.

To work out where the wood came from, researchers from the University of Arizona used methods of tree-ring analysis.

Christopher Guiterman and his colleagues compared tree-ring growth patterns from 170 great house timbers with the tree-ring growth patterns of trees from eight potential timber-harvesting areas in the nearby mountains.

They found that the Chuska and Zuni Mountains – more than 46 miles (75km) away were the most likely sources for 70 per cent of the wood used to build the houses.

Prior to 1,020AD nearly all of the wood came from south of Chaco Canyon in the Zuni Mountains.

‘We found that a previously unrecognised timber source, the Zuni Mountains, supplied construction beams as early as the 850s in the Common Era (AD),’ the researchers wrote.

By 1,060 AD most of the beams came from the Chuska Mountains to the west.

The first excavators of the great houses in the early 20th century speculated that construction timbers were harvested locally, perhaps resulting in deforestation of the surrounding landscape. A shot of Pueblo Bonito in the Chaco Culture National Historical Park, New Mexico is shown above

The first excavators of the great houses in the early 20th century speculated that construction timbers were harvested locally, perhaps resulting in deforestation of the surrounding landscape. A shot of Pueblo Bonito in the Chaco Culture National Historical Park, New Mexico is shown above

The new study found that the Chuska and Zuni Mountains - more than 46 miles (75km) away were the most likely sources for 70 per cent of the wood used to build the houses in Chaco Canyon (shown on a modern map)

The new study found that the Chuska and Zuni Mountains – more than 46 miles (75km) away were the most likely sources for 70 per cent of the wood used to build the houses in Chaco Canyon (shown on a modern map)

The shift from the Zunis to the Chuskas coincided with substantial expansion of Chaco Canyon society, including enlargement of existing great houses and the addition of seven new great houses.

‘It also coincides with the proliferation of Chuskan stone tools and pottery in the archaeological recors of Chaco Canyon, further underscoring the link between land use and occupation in the Chuska area and the peak of great house construction,’ the study continued.

Prior to 1,020 AD nearly all of the wood came from south of Chaco Canyon in the Zuni Mountains, but by 1,060 AD most of the beams came from the Chuska Mountains to the west. A wooden joist is shown

Prior to 1,020 AD nearly all of the wood came from south of Chaco Canyon in the Zuni Mountains, but by 1,060 AD most of the beams came from the Chuska Mountains to the west. A wooden joist is shown

The shift from the Zunis to the Chuskas coincided with substantial expansion of Chaco Canyon society, including enlargement of existing great houses and the addition of seven new great houses. Some petroglyphs from the settlement are shown above

The shift from the Zunis to the Chuskas coincided with substantial expansion of Chaco Canyon society, including enlargement of existing great houses and the addition of seven new great houses. Some petroglyphs from the settlement are shown above