Former travelers glimpse as authors of the huge mysterious circles drawn in the desert terrain of southern Peru. They were probably made as offerings during their breaks.
New research proves that circular geoglyphs are located along old transport routes. The marks may have been made for many centuries, from the year 200 to the 1400s of our era.
"People made these geoglyphs 'on the road' in both senses of the term," said study co-author Justin Jennings, curator of New World archeology at the Royal Ontario Museum in Toronto. The findings were published in Antiquity.
"They are in the middle of a trip, and they are doing this work, and of course, when you are in the middle of a trip, you are doing it during a pit stop," he added, explaining the close link between geoglyphs and causeways.
Jennings and his team are working on a larger project on long distance transportation in Peru in the time before Spanish colonization. The trips in this era occurred on foot, with llamas as beasts of burden. The current study focused on the Sihuas valley in southern Peru.
The researchers used a combination of field work, unmanned aerial imagery and satellite imagery to accurately map the location of ancient footpaths and circular geoglyphs, ranging in size from 3 to 55 meters in diameter.
The geoglyphs are made easily and quickly, Jennings told Live Science. They are constructed simply by removing rocks and soil from the reddish-brown soil, exposing a lighter layer of sediment below the surface. Sometimes the circles contain broken pottery or small hiding places of painted stones, as if someone had made an offering.
The geoglyphs look something like the famous Nazca Lines, also in southern Peru, which were also made by separating the upper sediment. But the Nazca Lines are much more complicated than the circles of Peru, since they represent animals such as jaguars and monkeys and reach up to 370 meters in length.
After mapping the geoglyphs and circular routes, the researchers drew virtual "buffer zones" around the remnants of the routes. Then, the scientists counted the number of geoglyphs that appeared in each zone, from 25 to 200 meters. The measurements seemed to indicate that geoglyphs were more likely to be near a road than away from one. To be sure, the researchers also generated 1,000 random points on their maps to compare.
The geoglyphs were "strongly associated with roads compared to what we would expect at random points, "said study co-author Peter Bikoulis, a graduate student in anthropology at the University of Toronto.
The geoglyphs of a ring were the most common, but there were also geoglyphs made of two or three concentric circles; those tended to contain more artifacts.
The geoglyphs were often in what Jennings called "turning points," where the road or view changed. They were particularly frequent in the places where the trails reached 800 meters from the valleys to the flat landscape of "pampa".
"You're climbing for about an hour or so of a pretty steep climb, and you finally get up there," Jennings said. "Now it's quite flat, you can see all these big snowy peaks, it's a very different sight, it's a moment of change, a moment of rest."
Even today, Andes shepherds sometimes create "apachetas," or stone cairns where they can leave a cigarette or spill some alcohol as an offering to mountain spirits, Jennings said. Circular geoglyphs may have been made with similar motivations, he said. Maybe, these points they were taken for sacred by the travelers of yesteryear, and these people were moved to mark their paths while they rested on the road.
The geoglyphs are difficult to date accurately, said Jennings, but they seem to come mostly from the year 600 and the 1000 of our era, a time known as the Late Intermediate Period when people traveled farther and commercialized products throughout the region. Today, many of the llama trails that people created are disappearing as irrigation and agriculture take over the Pampas. The authors of the new study are working quickly to document the region through drones and satellites before these old marks disappear.