Did the ancient Peruvians know how to soften rock? The mystery of Sacsayhuamán
When you look at the gigantic megalithic constructions that the Inca empire left behind, what immediately catches your eye is the incredible precision with which the stone blocks were positioned, some of which weigh more than 150 tons. How could such a primitive civilization create such precise architectural works?
In the southern sierra of Peru, at more than 3400 meters above sea level, lies Cuzco, the ancient capital of the Inca Empire.
Here it is possible to observe one of the most disconcerting architectural creations of South American archaeology: Calle Hatun Rumiyuq, the street that goes from the Plaza de Armas to the Barrio de San Blas.
The street is bordered by an incredible stone wall built dry, using a series of boulders carefully cut to fit perfectly next to each other. The boulders match so perfectly that not even a pin can be inserted into the crack between one and the other.
A stone is set in the wall which, more than any other, has always attracted the attention of researchers and tourists: it is the famous "stone of the twelve angles", a large boulder perfectly sculpted to match the stones that surround him. The precision of the assembly is truly staggering.
The terraces of Sacsayhuamán
About 2 kilometers north of Cuzco, at an altitude of 3700 meters, is Sacsayhuamán, a fortified complex made of stone that extends over an area of 3 thousand hectares.
Here too the technique of assembling the stone structures shows a precision that is unparalleled in America. Some of the rocks used by ancient builders reach 150 tons, a weight that we would have difficulty moving even with the modern equipment at our disposal.
The precision with which the blocks were placed, combined with the rounded corners of some of them, the variety of interlocking shapes and the way the walls protrude inward, has puzzled scientists for decades.
How did the Incas manage to create such precise works with only stone tools at their disposal?
To date, the method used by the Inca to match the engravings between the stone blocks with obsessive precision is still unknown, especially because no tool has been found near the site.
The "official" explanation is that the Incas somehow managed to guess the shape to give to the blocks using simple stone tools. Basically, they placed the stone in place, observed the shape of the adjacent ones and put it down to create the shape.
Then they raised it again and if it didn't match they repeated the operation until the blocks matched perfectly. All of this would be done with boulders weighing up to 100 tons. But is it possible to imagine such a complex and tiring procedure?
Considering the absolute precision of the cuts, which would have been achieved using stone tools, and the repeated raising of the mammoth blocks without the use of mechanical cranes, the entire process appears extraordinarily unlikely.
In history books we read that Sacsayhuamán was occupied by the Incas at the time of the conquistadors and that its construction work was completed in 1508. But Garcilaso de la Vega, a Peruvian writer born in 1539 in Cuzco, claimed to have no idea on how the structures of Sacsayhuamán were built.
Furthermore, when the Spanish conquistadors arrived in Peru, they learned from the Incas themselves that the megalithic structures had been there long before them, built by a different people.
If the builders were older than the Incas, he would like to say that there existed a much more advanced civilization of which we know almost nothing, except that it would have had the possibility of creating a fortress like that of Sacsayhuamán.
Alternative theory
Recently, an interesting theory has been put forward to try to explain the extraordinary modeling of the stone blocks and which has its roots in a legend reported by the first explorers who arrived in the area, such as Hiram Bingham and the legendary Parcy Fawett.
Legend states that the ancients were in possession of a particular liquid obtained from plants, capable of making the stone soft and easy to shape. Later in 1983, Jorge A. Lira, a Catholic priest, claimed to have reproduced the technique for softening the rock, but was unable to make the stones solid again.
Others have even hypothesized that the builders of Sacsayhuamán were able to melt the rock to give it the desired shape, but very high temperatures would have been necessary to obtain such an effect.
However, while theories remain speculative, one can be fairly certain that stone hammers and repeated lifting cannot guarantee the precision and strength needed to make a structure like Sacsayhuamán.
Enigmatic monuments like these invite us to learn more about our past, so that we realize how advanced our ancestors may have been.
