The ridge is 8000 feet into the sky and in relative terms it is a razor's edge, yet the Incas still wanted to build a palace here for some reason. So during the 15th century a king-warrior named Pachacuti started to layout plans for a royal estate. As Ken Wright states, one of the many problems to overcome and the biggest, would have been landslides and so stabilizing the slopes was priority one (2009). As studied the site work and foundations seem to take up 50% to 60% of all work completed at the site over the 90 year build time. Due to heavy rains and steep slopes this was a necessary evil to spend such an exorbitant amount of time and money.
Through more investigations the site work and drainage composed of three material choices; topsoil, sandy gravel and white granite. This vast system of underground work for drainage was needed to keep Machu Picchu on the hillside otherwise it would not be there today. This is because the average rainfall in this area is 76 inches and during the wet season mostly which last seven months. By compassion, that is almost three times as much rain as Chicago sees in a year. One interesting find to go along with the drainage system was the white granite, which seemed to be the waste ruble of the buildings which sit on top. So Wright (2009) surmises that the original Inca buildings would have been white and not the Grey weathered stone color we see today.
The next would have been the terraces and lots of them. Over 700 follow gracefully along the topographic elevation lines with curves and straights. The water is allowed to drain deep below into the ground and safely away from the hillside as not to wash the entire structure down with it into the river below. They not only serve as foundations for the various building and plazas of the site, but also soil stabilization for the plant growing fields for their agricultural needs (Wright 2009) and walking paths along the hillside. These are the fundamental building blocks for the longevity of Machu Picchu.
Unfortunately, this sounds all to familiar to one Architecture class on SIU campus and that would be ArC 242 Building Tech I: Wood. We are building a new stage, amphitheater seating and entrance benches out at the Touch of Nature campus near Giant City State Park. Nonetheless, weather has not been our best friend out there with all the rain and cold. The students are in the process of trenching, cutting, digging, draining and back filling 9 terraces, much like the Incas (in a somewhat smaller scale, but do not mention that to the ones digging) with gravel, sand, soil and railroad ties. We are also using string lines, water levels and "eyeballs" to get everything plumb, level and straight, much like the Incas.
Bredar, J. (Interviewer) & Wright, K. (Interviewee). (2009). A Marvel of Inca Engineering [Interview transcript]. Retrived from NOVAbeta Ancients Worlds website:http://www.pbs.org/