10,000-year-old ochre mines discovered in underwater Mexican caves
This expedition provides the first look into human activity in these ancient mining sites and the researchers say it will help us learn more about the earliest peoples of the Americas.
The world’s oldest known ochre mines have been discovered in underwater caves in Mexico’s Yucatan Peninsula by researchers from McMaster University and Mexico’s Quintana Roo Aquifer System Research Center (CINDAQ).
The elaborate cave passages were once dry but became submerged by postglacial sea level rise over 8,000 years ago, which created the ideal conditions to preserve the caves and their traces of human activity.
The researchers say that the evidence they collected indicates that people likely explored the caves to mine red ochre, an iron oxide earth mineral pigment that was widely used by the earliest inhabitants in North America. Throughout history, many civilizations have used red ochre for paintings, mortuary practices, hide tanning and personal adornment.
The researchers published their findings in Science Advances and say that in addition to mining, the caves could have been used for temporary shelter, access to fresh water, rituals or intentional burial of human remains, however, none are firmly substantiated by the available archaeological evidence.
Before the caves were flooded by the rising oceans, the ochre miners focused their activity to an area referred to as La Mina, which is located along the eastern coastline of Quintana Roo and is approximately within 8 to 10 km inland of the present-day coastline.
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Nearly 100 caves were explored and samples were collected in three cave systems spanning 7,000 metres. The study states that “evidence of human activity in La Mina is abundantly clear” with 166 locations being marked with broken stalactites, which were likely used as navigational markers to direct the miners to the ochre pits.
Digging tools, charcoal, fire pits and skeletons are some of the most remarkable discoveries. Radiocarbon dating charcoal and reviewing documental regional records of postglacial sea level rise were some of the strategies that the researchers used to establish the age and duration of mining activities in the caves.
Brandi MacDonald, an assistant research professor at the University of Missouri, analyzed sediment samples and confirmed that ochre mining was the objective of the people that ventured into these caves thousands of years ago.
“What’s really remarkable about the site is the preservation, this is incredibly rare in archeology to find evidence for [human] activity that is this old and this well preserved. It shows that there was group cooperation. The activities were quite sophisticated the amount of raw material that they were moving just to extract the ochre is unlike anything I’ve ever seen before,” said MacDonald during an interview with CINDAQ.
This expedition provides the first look into human activity in these preserved mining sites and the researchers say it will help us learn more about the earliest peoples of the Americas.
“Now that we are alerted to underground ochre mining and its archaeological signatures, additional discoveries are certain to be made in the nearly 2000 km of known cave systems, which will clarify the process and chronology of Paleoindian ochre mining in Quintana Roo,” the study concludes.
