From far away, El Volcán in the Nepeña Valley of coastal Peru might look like a natural feature in the landscape.
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. [In Photos: Earthly Mounds Shaped Like Animals]
“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.