Preface and General
MATERIALS AND INKAN LITHIC TECHNOLOGY
It is evident that Quechuas searched for some immortality in their works. That is the reason why they preferred the hardest stones; no matter how far away the quarries were from the spots where they would raise those monuments to work and order. The most preferred materials were rocks of igneous or volcanic origins, being extrusive or intrusive ones. These last ones were the favorite, that is, magma or lava that was cooled off in huge profundities inside the earth; after millions of years these volcanic formations could protrude forming what is known as Stocks and Batholiths, that contain rocks harder that those cooled off on the earth surface.
The softest rocks used in Inkan walls were Limestones that are sedimentary rocks with marine origins having 3° of hardness in the MOHS Scale (Scale from 1 to 10 degrees, in which the softest material is talc with 1° and the hardest is diamond with 10°) and a compression resistance from 200 to 500 Kg/cm². Limestones were used in Saqsaywaman where the Yunkaypata limestone formation is found, Chinchero, Yucay, Tarawasi, etc. In the Peruvian Andes, limestones that contain a high amount of calcium carbonate are used as fertilizers, adding to farm soils the raw rock previously pulverized or as lime. Another type of rock used in the region were Quartzites, rocks that were mostly formed by metamorphism of sandstones. They are formed principally by quartz as their name insinuates it and are as hard as quartz; they are frequent in Paleozoic formations in Peru and in some Mesozoic ones; they have 5° of hardness and a compression resistance of 800 Kg/cm². Basalts also had an extensive use in Inkan Architecture. Basalt is the most abundant of extrusive rocks, it is the volcanic correspondent of the intrusive rock called "gabro", it has from 5° to 6° of hardness in the MOHS scale and a resistance of 1200 Kg/cm²; in Qosqo City, the basalt of Rumiqolqa is the most used as cobblestones to pave the streets. Diorites had also a very diffused use among the Quechuas. They are equigranular igneous rocks mainly composite of plagioclase feldspar and one or more dark minerals; their hardness is of 6° and their resistance of 1200 Kg/cm². In Qosqo, green diorites are found in San Blas and the skirts of Saqsaywaman and they were used for construction of the Inka Roqa's palace in Hatunrumiyoq street in which the famous twelve angled stone is found. Andesites are abundant in the region and have an excellent quality being the most preferred in the Inkan City architecture. Andesites get their name because of the huge amount found in the Andes and are the volcanic correspondent of diorites. They possess different colors and are generally dark; they have 6° of hardness and 1200 Kg/cm² of compression resistance. Along the Qosqo Valley some andesite outcrops are found in the old volcanic centers of Waqoto, Oropeza, Lucre and Rumiqolqa. Granites were broadly used too; they are intrusive igneous rocks and have an equigranular texture (big and uniform grain) that differentiate them from the extrusives. They contain an average of about 60% of feldspar, 30% of quartz and 10% of dark minerals. They have 6° to 7° of hardness and a resistance of 1200 Kg/cm²; the classical example of granite among us is that of the Vilcabamba Batholith where Machupicchu is found. Likewise, Sandstones were used in Inkan walls, they are sedimentary rocks formed by strengthening of single sand grains. They have a hardness of 7° in the MOHS scale and from 300 to 800 Kg/cm² of compression resistance; like sand they were also used as abrasives in order to polish some other rock types.
Normally, Inkan buildings leave even the most cautious, serene and wise visitors perplexed and even stunned. Incompetency for understanding the Quechuas human work has led in so many cases to utter some different hypothesis, from the most prudent and science oriented ones to the most disheveled, vain and fancy ones. When conquistadors arrived, many of them could not explain what was standing in front of them and according to their medieval way of thinking argued that "Indians" that were found in the Andes were unable to make such a grandeur and attributed it as work of devils, demons or malign spirits. This same incompetency leads so many people nowadays to consider that all this gigantic work was made by extraterrestrial beings with a superior technology and advanced philosophy that came to leave a sample of their power and capacity; precisely over here!!, Why they did not go on with their work here or somewhere else in any other corner of the world?. It seems that this last hypothesis argued by Erich von Däniken is simply a product of a very fictional way of thinking.
Today, quarries containing lithic material for Inkan buildings are easily identified all over the Tawantinsuyo. Normally with the help of accumulated knowledge about ancient Peruvians and if geography was not modified it is still possible to identify all the substructure created for fracturing, carving, transporting and manipulating the rocks. Without any doubt, the most eloquent example of all that is found in the Kachiqhata quarries, about 4 Kms. (2.5 miles) away from Ollantaytambo. There are but a few serious studies done about Inkan stonemasonry, among which stand out that done by Jean-Pierre Protzen in Kachiqata and Rumiqolqa.
Fracturing or detaching rocks from a mountain was perhaps the hardest work in the whole process. For that purpose, the existing fissures or fractures in the mountain were used frequently; fissures from which rocks were forced to be detached with the help of bronze crowbars that could be one meter or longer ones, like the ones found in museums; for this work they could use wooden girders too. On the other hand, it is suggested that some metal chisels were also used in order to make successive holes making rocks crack following the alignment of perforations. Likewise, it is argued that for splitting the rocks away expansion of wooden wedges was used. Those wedges were placed in successive holes made in the rock and then soaked with water. It is also speculated about the possibility of fracturing rocks, perforating one or more grooves that were filled up with water, that when frozen during nighttime made rocks detach. A long time ago it was also believed that for splitting rocks they were heated with fire and suddenly cooled off with cold water; this process produces rock fracture in many and irregular pieces that could be used in rough works and not precisely in those of best quality.
Dressing surfaces and shapes from very irregular stones urged a great specialization that was reached in millennia of cultural evolution in the Andes. Discovered or learned techniques by pre-Inkan Nations were improved, perfected and widely disseminated among the Quechuas. With some disregard some authors argue that Inkas did not invent anything except the trapezoidal shape hollows in the walls; but, what is evident, is that no other nation or town before them had anything similar to their stonework. Chroniclers indicate that in order to dress stones Inkas used some other harder ones, this is what tradition teaches and also what was demonstrated. In some quarries and different archaeological diggings some different harder stones were found; harder than the ones that were being shaped or are naturally found in the site. Those harder ones are the stone hammers that tradition names as Jiwaya or Jiwayo used to smooth off or carve building stones. They are compact and heavy sedimentary rocks containing ferric oxides: hematite (Fe2O3) originates a brick-reddish color in the rock, ferrous oxide (FeO) produces a grayish or blackish color, goethite (Fe2O3.H2O) originates a brown color while that limonite (2Fe2O3.3H2O) a yellowish color. These rocks may contain even about 6% of iron. Likewise, some hammers of basalt and epidorite rounded cobblestones were used; those are the famous qollotas that are found in river beds and have a hardness that is similar or superior than worked stones; the difference is in their great compactness. Hard rock hammers were frequently ovoidal and used through percussion (bumping) over the stones for buildings that were smoothed off in a slow and laborious work. Their weight was according to the duties they had to perform. So, the heaviest ones weighing about 10 Kg. (22 Lb.) served for smoothing stones off while the lightest ones of approximately 1 Kg. (2.2 Lb.) were for making shapes regular or adjusting edges. It is frequently heard that obsidians were used for dressing stones too; that is vaguely probable because they are a shiny sort of volcanic glass resulting from siliceous magmas that were cooled off; they would be useless for bumping but were used as knives, scrapers and spearheads or arrowheads. The final dressing and polishing of building stones was made through abrasion or friction with sandstones or simply sand as abrasives and abundant water.
Even until some few years ago it was believed that Inkas did not manage using metal instruments in their stone works because there was a lack of enough evidences and testimonies. Nevertheless, modern studies demonstrated that all that is not true. Bronze, the alloy of tin and copper was the hardest metal used by Quechuas. Normally, in the different museums there are bronze tools of different alloys correctly tempered and of great hardness. The most serious study about the matter was made by Yale University professor Robert B. Gordon, who studied a collection of metal objects taken by Hiram Bingham from Machupicchu. Among them he found 13 bronze instruments apparently made for heavy duty works; later analysis and exhaustive tests gave the conclusion that 1 of them was used to carve wood, 2 were designed for stone works but were not used and the 10 remaining ones were used as real chisels: in order to detach stone particles with impact produced being hit on their upper edge. Thus, it is also demonstrated that Inkas used metal tools in order to carve stones.
There are in many stones, very fine cuts that would be impossible to be made by bumping or using chisels. Many scholars suggest that they were made using some sort of "saws" consisting of wires or fine copper or bronze blades and using some abrasive and a lot of water. Moreover, there are some holes perforated in rocks; they show clear remains of having been made using rotating perforators and without any doubt that concerns the use of augers made on metal or hard wood that were rotated using an arch, water and sand as abrasive.
Another aspect that causes wonder is the carriage of boulders for buildings. In a very simple way it is known that in order to do it, the ground was smoothed constructing very wide roads between the quarries and the building site. Then, when slopes were found, that is, for lifting or taking stones down, some ramparts or inclined planes were built like the inclined plane that is seen in Ollantaytambo. Possessing all this substructure some other auxiliary elements were used too, such as round or rolling stones like the ones which are found near Saqsaywaman in the Callañaupa family's property, and log rollers used as wheels. These elements made all together real bearing systems that allowed transportation using besides the power of dozens, hundreds and even thousands of workers. They had to push or pull the boulders with the help of pulleys, metal or wood levers, and ropes made of llama leather, agave fibers or some other resistant materials.