Secrets of The Incas: How They Masterfully Cut and Fitted Stones

For centuries, the remarkable architectural achievements of the Inca civilization have fascinated and puzzled historians and archaeologists alike. One of the most impressive feats of ancient construction is the precision and exactitude used in cutting and fitting monumental stones, many of which weigh hundreds of tons. How did the Incas accomplish this? While some of their methods are known, others remain shrouded in mystery.

Tools and Techniques

With a profound sense of dedication, the Incas employed a range of tools to cut and polish their stones. Copper tools and other stones were the primary cutting instruments, supplemented by the use of sand for fine polishing. More advanced tools, such as arsenical bronze chisels, were used for harder stones.

A notable resource for understanding Inca quarrying and stonecutting is the book Inca Quarrying and Stonecutting, authored by Jean-Pierre Protzen. This book provides detailed insights into the methods used by the Incas to achieve their remarkable architectural feats.

Flattening and Smoothing

The process of cutting and fitting stones began with flattening the surfaces as much as possible using heavy pounding stones from nearby rivers. The dust generated from this process was collected and spread liberally on the surfaces being worked. Portions that stood proud were then painted with water and pounded again to achieve a smooth surface.

Less skilled masons would round the edges of the joint boundaries to make it easier to handle these massive stones. This process was repeated until the stones were prepared for their final alignment.

The Challenge of Fitting Stones

One of the most challenging aspects of the Inca stonecutting process was precisely fitting the stones together. This required creating a template and using it to cut mating sockets into the mating surfaces. It is believed that the sockets were always cut first because they were “finished” stones and less likely to shift during the lengthy process of cutting.

Several hypotheses have been proposed to explain how the sockets were cut. One popular theory suggests that a soft wet clay was mixed with stone flour and pressed against the protruding portions of the rocks, then pulled away to create a mold that could be used to match the socket. This method would have required an incredibly trained eye, making it a complex and time-consuming process.

It is important to note that many of these joints required working on three or more stones simultaneously. Considering that many of these stones were as tall as a man and weighed a hundred tons or more, this feat was nearly impossible to achieve. It is believed that only a few master masons were present on a given site due to the extreme skill required.

The iterative nature of this process meant that stones were picked up, placed, and removed multiple times until the desired precision was achieved. This process likely demanded considerable physical and mental endurance, possibly requiring hundreds of fittings to achieve the perfect alignment.

Despite the many theories, the exact method used by the Inca masons to precisely fit these massive stones together remains a subject of ongoing investigation and debate. Nonetheless, the achievements of the Inca stonecutters stand as a testament to the ingenuity and skill of these ancient builders.