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Standing at the rim of Quechuyuc Muyu, peering down at the the central terraced monument of Moray, I was awestruck.
For years, I had admired pictures, but they couldn’t begin to do the actual site justice.
Still, I snapped a photo and sent it to my father in the United States.
His email reply came back almost immediately: “Wow, what’s that?”
My guide’s description still fresh in my mind, I tapped out a reply with my thumbs:
“Moray. It’s a 37-meter-deep, open air Inca greenhouse. The lower terraces create their own micro-climates. The site is about 3500 m.a.s.l. but the temperature inside the structure gets so warm, you could cultivate jungle fruits on the lower terraces.”
Whether my abbreviated historical description was entirely accurate got me thinking, then reading. As it turns out, the general premise, accepted by most Cusco guides, is the subject of some debate.
That’s when American geologist Robert Shippee and U.S. Navy pilot Lt. George Johnson flew over the site as part of an aerial photographic expedition of the Andes.
Their photos of the three immense, and one smaller, set of perfect concentric circles monumentally carved into the terrain marked a major archaeological discovery.
They described it a year later in the Geographical Review as, “A group of amphitheaters on the Maras Pampa about fifteen miles northwest of Cuzco that seem to have escaped the notice of archeological explorers of the region.”
“The priests in a church in Cuzco knew of their existence and said they had been used by the Incas for religious presentations during their fiestas,” Shippee wrote. “We have, however, not been able to find any mention of them in the literature on the region.”
Moray is located at the northeastern base of Wayñunmarka Mountain, roughly halfway between the Inca capital Cuzco and Machu Picchu. Inca civil engineers constructed the geometric landscape masterpiece during the 15th and early 16th centuries.
Covering 92 acres, the four terraced sinkholes — known as Muyus — range from 130 to nearly 400 feet in diameter.
The agricultural terraces were fed by a complex drip irrigation system, the remains of which are clearly visible today. Small holding reservoirs, hydraulic channels and carved stone “paqcha” conduits controlled the flow of natural spring water to a mathematically precise trickle.
If left to flow unabated, the water would quickly erode the terraces and the muyus would revert to their natural state — massive, and massively unstable, sink holes.
The prevailing theory goes that the Inca plugged the sink holes with a mega drainage and soil system, then tested their crop varieties on Moray’s ancient terraces, which today are known locally as “the greenhouse of the Inca.”
Many historians and scientists believe the Inca conducted experiments to determine which varieties of grains, beans, potatoes and — most importantly — maize were best adapted to different combinations of temperature and altitude. Strains that could resist frost, and excessive or deficient rainfall, in hot and cold years were cultivated. Mastery of agriculture across a vast empire, including punishing Andean terrain, is what allowed the Inca to successfully feed 12 million subjects.
Prof. John Earls, at Pontificia Universidad Catolica del Peru, led a study in the 1980s, measuring the soil temperatures of the Moray terraces. His data appeared to confirm that the Inca designed stable micro-climates at different terrace levels in various sectors of the muyus.
Above the rim of the terraces, the 11,600-foot plateau of the Pampa de Maras has an average monthly temperature of 60 degrees Fahrenheit, which dips considerably at night, occasionally below freezing, during the South American winter months of May through July.
Earls found that below the rim, the giant inverted concentric cone platforms offer a range of micro-climates, with differing soil temperatures and humidity levels.
As would be expected, the temperature at the rim can be 27 degrees Fahrenheit cooler than at the bottom, 40 yards below.
The nearly perfect concentric retaining walls open up to the sky in such a way that during the midday zenith of the sun, there are no shadows on any terrace at any level.
Yet, Earls found that in specific sectors of the muyus, the temperatures were remarkably warmer at the middle four terraces than the lower four terraces. He theorized that Inca agronomists measured temperature differences by placing containers of water to freeze at night on the terraces, then checked rates of thaw after the morning sunrise.
Keeping a calendar of the seasons for planting and harvest was also an important part of the picture at Moray. Just like at other Inca monumental structures, beams of sunlight and columns of shadow take on purposeful astronomical significance during the day of the winter solstice, as well as the Sept. 22 and March 21 equinoxes.
Last year, the brilliant water engineer Kenneth R. Wright and his talented photographer, travel writer wife, Ruth Wright, along with archaeologists Alfedo Valencia Zegarra and Gordon McEwan, published a fascinating book Moray: Inca Engineering Mystery.
The Wrights and their co-authors respectfully disagreed with Prof. Earls’ conclusions. They argue that Moray was not in fact an agricultural experimental greenhouse, but instead a more strictly religious and ceremonial center. They also maintain that Moray was left unfinished after Inca construction of the site was interrupted in 1532 by the Spanish Conquest.
The book offers great insight into the planning, hydrology and construction of Moray, some of which is cited in this blog post. It also includes a Moray walking tour description.
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