The wood in the monumental "great houses" built in Chaco Canyon by ancient Puebloans came from two different mountain ranges... The UA scientists are the first to report that before 1020, most of the wood came from the Zuni Mountains about 50 miles (75 km) to the south. The species of tree used in the buildings did not grow nearby, so the trees must have been transported from distant mountain ranges. About 240,000 trees were used to build massive structures, some five stories high and with hundreds of rooms, in New Mexico's arid, rocky Chaco Canyon during the time period...