Preface and General
Prior to construction of any building, palace, temple, village or city; Quechuas had a process of physical planning tending to ensure later success. Undeniably, knowledge used was not only a product of creative capacity of these Andean villagers, but a many centuries accumulation of continuous cultural development. As it was indicated before, Peruvian culture has an age from 18 to 20 thousand years B.C. Peruvian scholar Victor Angles states: " Inkan stage is the shortest in the development of pre-Hispanic people, it is the last political time characterized by a quick and powerful military expansion that crowns long earlier stages of gradual formation of nations".
Prior to executing any construction Inkas made some sketches and designs, and models or maquettes in scales which measurement systems mainly based in anthropometry (measures with relationship to the human body: arms, elbows, feet, steps, spans, etc.) are lost. A demonstration of this in-advance planning are the large amount of maquettes found in almost all the archaeological museums in the country; they are carved in stone or made in pottery.
Around the world, no other ancient or modern civilization could ever reach the technique, skills and ease to carve lithic material as Quechuas did in this corner of the earth. Inkas are recognized among some other aspects, for their balanced social organization, their mastered and peculiar way to work stones, their advanced knowledge in planning and engineering, and because of their epoch and without intervention or influence from other intercontinental cultures they developed one of the most advanced civilizations of the planet.
There are still some doubts about the way how stones were fitted so precisely. Those doubts are based on the lack of chronicles or detailed ancient records about those techniques. There are some hypothesis that are framed inside logical possibilities: the most feasible indicates that work was very slow but effective and as it is normal walls were started by the lower part taking care of just the lateral fits, the following upper row was more complex because stones had to fit laterally as well as in the lower joints. In this case it is proved practically everywhere in Qosqo that upper faces of lower stones were carved slowly bumping them with stone hammers according to the shape of the inferior surface of upper stones. The work was relatively simple when manipulating small or medium stones, because they could be placed or tried many times; but problems arose when working with megalithic boulders of dozens and even hundreds of tons. Reality suggests that Quechuas could use natural size models or maquettes made on light materials and perhaps clay. Those models were supposed to be reproduced exactly on huge boulders; surely, use of this method helped enormously making works easier. Another respected opinion states that they could use in a certain way a present day technique that consists in copying with some wires or metal tapes the shape of the desired stones (in Qosqo's archaeological museum there is a very long silver tape), thus they made possible a really complex work.
Many medium and large stones that are part of Inkan walls have almost always 2 high relief carvings or moldings in the lower part of their faces. In some cases like in Saqsaywaman those carvings are in low relief and served for facilitating transportation, lifting, and manipulation of stones during the building process,. Many of those moldings were removed once the wall was finished, but because of some unknown reason certain stones still keep them. There are some exceptional cases like in Qosqo's Qorikancha where the inside face of the semi-round wall known as "solar drum" shows unusual moldings surrounding the trapezoidal niche; it is evident that they were not used for manipulating the blocks but they had some religious duty or ideo-graphic meaning that is lost.
Among the materials used in Inkan walls is the adobe or sun dried mud brick. Many buildings and even whole cities in the Tawantinsuyo were made with this material; that is the case of Pachacamaq which stands south of Lima. In order to make "adobes" some good quality earth was chosen preferably clayish that was mixed with ichu the native wild bunch grass, and in certain cases with llama or alpaca wool too. All these materials were blended with water, placed in rectangular molds and then dried to the sun. Adobe buildings were and are still preferred in the Andes because they are easy to get and have thermal properties; they last forever when covered with thatched or tile roofs.
In the Inkan stone buildings there are diverse types of walls and bondings. They are resumed in five basic ones:
- The Rustic or " Pirka" type. Made with non carved rough stones accommodated without much care; the empty spaces in the joints were filled up hwit small stones and abundant mud mortar. This type was used for construction of farming terraces, storehouses, homes for common people, etc.
- The Cellular type. It has an aspect that is similar to the structure of a honeycomb. It was normally made with small or medium polygonal limestones; examples of this type are found in Qolqanpata, Chinchero, Tarawasi, etc.
- The Enchased type. Made with polygonal, medium size igneous stones. Examples of this type are the Principal Temple in Ollantaytambo, the Three Windows Temple in Machupicchu, Hatun Rumiyoq in Qosqo, etc.
- The Sedimentary or Imperial Inkan. Consisting basically of medium sized stones preferably andesites of regular height in horizontal rows that give the impression of being totally rectangular. This is the bond that has the most perfect polished joints "where it is impossible to slip even a shaving blade or a paper sheet". It has no mortar except a very thin clay screen as a sealant that seems to have been placed in liquefied or liquid state to enable moving and manipulating stones.
- The Cyclopean type. Also known as Megalithic is characterized for containing enormous boulders that in some cases can reach 8.5 mts. (28 ft.) high; like those that are seen in Saqsaywaman or what is left from the high altar of the Main Temple in Ollantaytambo.
Besides, there are certain classical characteristics in palace and religious Inkan Architecture. On the wall surfaces, stone side views (cross sections) may be "cushioned" (semi-round edges), convex, beveled or flat. Meanwhile, their joints may be carved or polished. Normally, Inkan walls are leaning or have some inclination inwards. There is not a general rule or measurement for that inclination and its main duty was to search some balance between the walls that support each other. Commonly the lower stones are bigger or have more volume than the upper ones. Besides, Inkan walls are frequently wider on the base than on the superior part. Moreover, the classical shape of Inkan architecture is the trapezoid that gives a stability and balance sensation. It is undeniable that immortality was searched; the way how to make anti seismic buildings, everlasting and indestructible by any natural catastrophe. Only men, blinded by fanatical ideologies could destroy them partially.
Constructing the roofings urged highly qualified techniques and knowledge. They were generally made supported on wooden beams and covered with thatch of "ichu", the local wild grass. According to the shape of their coverings, roofs may be classified in 4: of a single watershed or slope; of two slopes; of four slopes and conical ones. Just imagine how impressive the roof structures of some huge buildings were, such as that of the Wiraqocha Temple in Raqchi that had a " Kallanka" structure of 92 X 25.25 Mts. (302 X 83 ft.) covering an area of 2,323 m² (25004 ft²). Due to materials used and the amount of rainfalls during the year, the roofs had a strong inclination varying from 50° to 65°. Because the local wild grass "ichu" does not last forever the roofs had a frequent maintenance. "Ichu" roofings must have been renewed every three or four years as it happens nowadays.
Another impressive element were the river canals such as those of the Watanay and the Willkamayu (Urubamba) Rivers that must have been built orderly and in straight lines. Even today in some sectors of these rivers it is possible to appreciate the lateral well-carved stone walls. Bridges were built in order to cross rivers and their bases are still identified. A fine example of bridges is the one seen today in Qheswachaka over the Apurimac River. It is made in community work by the people who use it and with the ancestral Andean technique. All the previous are some samples of native engineering and technology, that time, forgetfulness and the lack of identity darkened and are still darkening.