This is a photograph of the remnants of the Great House at Casa Grande.
At one time 2,000 people lived in Casa Grande and it had the most extensive canal system in North America, if not the world. It required an amazing amount of human labor and engineering to create the Great House, the remnants of which we saw today. These were clearly not uncivilized people. They were highly civilized. Europeans (Spanish) when they first encountered this house were stunned.
The main building material was caliche (cu-LEE-chee), a concrete like mixture of sand, clay, and calcium carbonate (limestone). It took 3,000 tons of caliche to build the Great House.
Caliche mud (water was added to the caliche) was layered to form walls that were about 4 ft. thick at the base, tapering toward the top. Hundreds of juniper, and fir trees were carried or floated down the Gila River to the village. Timbers were anchored in the wall for ceiling and floor supports.
Caliche is found as hard pan in most areas at depths of 6 inches to 2 feet. Sometimes I encountered in my trail walking in Arizona. It is hard like concrete. It can be softened in water, however, and that is why the ancestral people created mud with the addition of water to the caliche. That was stacked on to the buildings and then allowed to dry to a very hard material.
There is no evidence that the ancestral people invented the wheel. Since they had no draft animals, and since usually the rivers did not flow to their agricultural lands, they had to carry all of their building materials. It is still not understood how they were able to do that.
Since 3,000 tons (6 million pounds) of materials were needed for the construction of the Great House, that meant that 100,000 bags each with about 60 pounds of mud had to be carried up to the Great House.
The Great House consisted of a 4-storey structure on a mound of about 4 feet. The mound was used for the same reason that judges sit on a high bench and preachers stand above the congregation at their pulpit. It is a sign of prestige to be high up. The Administrators of the region likely wanted to be seen to possess prestige.
The first floor of the Great House consisted of a mound or platform. It was there solely for purposes of building it up so it looked more impressive and allow them to look over their canal system.
The walls were 7 feet tall even though they had few enemies. Why did they build so high? Our guide thought they were to give children who might have wondered away from a home a method of finding home, because the walls were visible from a considerable distance.
The second floor contained 5 rooms as did the 3rd floor. The 4th floor consisted of just one room.
As a result, timbers from the mountain trees had to be brought in by hand. It is likely that the ancestral people subcontracted the job by trading for such materials. 640 logs were needed for the Great House construction. The timbers came from about 50-75 miles away. I would not want to haul those timbers that far by hand.
The roof was made by spreading saguaro ribs across the beams with reeds covering them, and then topped with a final layer of caliche mud. Despite centuries of weathering and neglect the Great House remnants still stand testifying to the nature of the society of Ancestral People.
The doors of the Great House were quite small, not because the people were so small, but to keep out warm air.