The Inca site of Moray is one of the iconic places to visit in the Cusco region. Almost every one is blown away by the massive size of the principal “muyu” — the name for the four terraced-lined depressions — when walking up to the edge to see it for the first time.
Sadly, since 1981 a single myth has persisted and continues to be spread by every guide, across social media, and even by the government despite being proven wrong over a decade ago.
Through a series of studies from 1975-1976, Australian anthropologist Dr. John Earls (along with Gary Urton and Irene Silverblatt in the first year) conducted a series of soil temperature studies of the Moray muyus. Earls noted that the upper and northernmost terrace warmed up at different rates from the lower terraces due to the path of the sun and shadows resulting from the surrounding geography.
Based on the data he collected, Earls concluded that Moray had been an agricultural research center where different strains of crops like the Inca staples of maize, quinoa, and potatoes could be grown under different conditions in a single location.
This proposal, published in 1981 with Silverblatt, has become the overwhelming explanation for the site’s original purpose. Indeed, the myth of Moray has not evolved into the predominant concept that each level represents a 1° C difference in temperature — something that was not even part of Earls’ original proposition.
(Let’s be honest — does temperature change anywhere by 1° just because you climbed two meters or so? Of course not.)
Hydraulics engineer Kenneth Wright led an extensive study of the site that came to the conclusion that Moray simply could not have served as an Inca “agricultural research center” and that Earls’ conclusions could not be supported.
After extensive study, Wright (along with Alfredo Valencia Zegarra, Ruth Wright, and Gordon McEwan) published a highly detailed analysis of Moray and concluded that there is simply no evidence to support Earls’ agricultrual research station hypothesis:
– The site has soil that tends to be somewhat saline.
– The site is relatively small.
– Except for one building on Terrace 8 of Muyu A, there re no remains of buildings that could have served utilitarian functions to support research staff or house various strains of crop seeds and field research paraphernalia needed for research and agricultural control. We judged that single building to be a structure to house site managers. The other few buildings in Area F and Ceremonial Ridge G we judged to represent ceremonial and religious structures.
– Between Maras and Moray, we found no evidence of a trail that would handle heavy traffic to and from a research center. Moray was rather isolated, though it was part of the Sacred Valley trail system.
– Agricultural research by the Inca could have been conducted more easily on some of the thousands of terraces in the valley and side canyons of the Vilcanota River. This Sacred Valley area is known as the “bread basket” of the Inca.
– While soil temperature data demonstrate statistically different temperatures in various locations on the terraces, our analyses of the data show that they are not adequate to prove the agricultural research station hypothesis.
– In the muyu terraces, wide soil temperature variations exist from location to location and from month to month in modern times, depending on the exposure to sunlight; however, the temperature variations have nothing to do with terrace elevation, as some have surmised. One would predict that the lower terraces would be the warmest, but they are generally the coolest, due to soil moisture cooling.
– With inly 20 inches annual precipitation, the higher Muyu A terraces would require irrigation. The water supply in September and October tends to be meager, which would constrain agricultural research opportunities.
– An agricultural research station would be irrigated, yet the Inca knew that adding water to the muyu terraces would exacerbate the landslide problem. There is evidence that the circular terraces were not intended to be irrigated.
– The original muyu slopes were unstable. The Inca engineers worked hard to stabilize the landslide on the east side of Muyu A while building the terraces. They installed internal drains to remove lubricating water from the slip-plane of the landslide.
– Any irrigation of the terraces would cool the ground due to evaporation in fact 95% of irrigation water is “burned up” in cooling the soils and plants. Irrigation of the terraces would tend to homogenize the growing season sol temperature of the terraces to within one or two degrees Celsius.
– The circular terraces have no secondary rows of hydraulic drop structures to handle excess irrigation water, and the terraces often have adversely sloped surfaces.
– The circular terraces are perfectly formed and painstakingly consrtructed. They are “high prestige” terraces that were not intended for common agriculture.
– The extravagant geometric layout of circles and ovals of the Moray terraces do not point to a utilitarian function, but, rather to an expression of inca power and ability to reshape the earth.Kenneth Wright, et al (2011)
Even Earls’ former collaborator, Gary Urton, who has become one of the world’s leading experts on the Incas, has expressed doubts about Earls’ hypothesis.
“I don’t know is he just imagined that [theory] out of his very wide experience and knowledge of the Andes, Urton told Roger Atwood. “To tell the truth, I read his subsequent studies and and they didn’t seem definitive. It never seemed to me that they supported his theory that it was an agricultural research station.”
Despite all of this, Moray is one of the most amazing places to visit in Peru. Day tours lasting about 5-6 hours are incredibly inexpensive and more than worth it. I’ve been many times and still in awe of the site.
Likely, Moray was a ceremonial site, but as many enigmatic sites left behind by the Incas, we likely will never know for sure.
Atwood, R. “Mystery Cicles of the Andes,” in Archeology, The Archeological Institute of America, September/October, 2007.
Earls, J., and I Silverblatt. “Sobre la instrumentacion de la cosmologia en el sitio arquelogico de Moray.” In La tecnologia en el mundo Andina, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico. 1981.
Wright, K.R., A. V. Zegarra, R.M. Wright, and G.F. McEwan. Moray: Inca Engineering Mystery. Virginia: ASCE Press, 2011.
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