© Courtesy of Robert BenferEl Volcán in the Nepeña Valley of coastal Peru has archaeologists stumped as to when and why this mound was built, though it may have served as a place for a ceremony related to a total solar eclipse.
But this volcano is artificial, a mound or pyramid built by human hands with a crater dug out of the top. And some archaeologists are trying to figure out what it was used for.
Robert Benfer, a professor emeritus at the University of Missouri who focuses on biological anthropology, had previously found a series of mounds shaped like orcas, condors and other animals in coastal valleys in Peru. He was looking for more of those earthworks by surveying valleys north of Lima when he spotted the volcanic cone that stands 50 feet tall (15.5 meters).
"I knew that a mountain in the valley had a large archaeological site, San Isidro, with platforms oriented to the solstice," Benfer told Live Science. "So with my team, we climbed it to get a better view of the surrounding valley, and I saw the Volcán site from a platform."
In the 1960s, archaeologists had noted the volcano-like mound and identified it as artificial, but Benfer and his team decided to investigate further. As the researchers report in the latest issue of the journal Antiquity, they dug a trench into the inner crater of the volcano, and found a collapsed stairwell that descends below a layer of adobe bricks to a mud-plaster floor.
© Courtesy of Robert Benfer Archaeologists dug a trench into the inner crater of the volcano-shaped mound, finding a collapsed stairwell that descended to a mud-plaster floor.
Benfer believes this date range is important. During the 16th century, there would have been four total solar eclipses, visible from El Volcán, in short order: in A.D. 1521, 1538, 1539 and 1543. This would have been a rare occurrence. "The chances that four solar eclipses could occur during the probability distribution of the radiocarbon date of the hearth is less than 0.0003," Benfer told Live Science. (That's less than a 0.3 percent chance of occurring.)
In their paper, the researchers wrote that "the people of the northern and central coasts, the Yungas, unlike the later Incas, greeted eclipse[s] of the sun with joy, not fear." Benfer speculated that the fire might be all that's left of a ceremony linked to one of these eclipses.
The researchers are not sure when the mound was first built. It's possible that the original structure might be much older than the hearth. The nearby archaeological site at San Isidro was active during the Late Formative period (900 B.C.to 200 B.C.).
The meaning behind the mound's shape is also still unclear. Benfer noted that there are no volcanoes around El Volcán that would have served as models for its construction, if it was indeed meant to look like a volcano, and no other structures like it have been found in Peru.
Reader Comments
"This would have been a rare occurrence."
NASA has pinpoint accuracy when total LUNAR eclipses will occur. I imagine it's the same thing with total solar eclipses.
The ancients probably had the same methods available that NASA uses? But they're not so rare if NASA knows exactly when they will occur.
There's a similar misunderstanding with the so-called "blood moons" which is simply a total lunar eclipse—a full moon being wholly enveloped in Earth’s shadow.
A launch pad perhaps?