Ancient red cave lines in Wales may be art

Red markings inside Bacon Hole cave in Wales—first recorded in 1912—were long dismissed as natural iron deposits. A new high-tech analysis says the pigment was hematite and that the lines were arranged in a deliberate, structured pattern, suggesting they were

For more than a century, red streaks in a Welsh cave were treated as background—geology doing what geology does. Then a new round of scrutiny, backed by modern tools, landed on a different story: the markings inside Bacon Hole cave may have been made on purpose by ancient humans.

The cave lies about 50 miles west of Cardiff in Wales, and it was discovered in 1850. Sometime after, an Iron Age bowl was found in the mud, along with bones that appeared to have been modified by humans—evidence that led researchers to conclude the cave had once been occupied by prehistoric people.

But the attention that lasted a hundred years began with a much earlier moment. In 1912. a pair of archaeologists. William Sollas and Henri Breuil. found red pigment lines inside the cave and documented “10 or so lines of red pigment.” They argued the markings were not just stains—possibly the oldest example of art in the British Isles. and potentially dating to the Upper Paleolithic. the period estimated to fall between around 50. 000 and 12. 000 years ago.

That interpretation didn’t survive unchallenged. Others in the field dismissed the red lines as natural phenomena. such as iron oxide deposits that can also appear red. And the work that could have settled the question became harder when graffiti complicated archaeological investigations. leaving the site largely untouched by scientists until now.

During a series of expeditions from 2022 to 2024, archaeologists returned with equipment built for seeing what older fieldwork might miss. Using high-definition photography, color filter algorithms, spectroscopes, and other high-tech tools, they examined the markings in detail. They also compared samples of the marks with material taken from nearby rocks and from iron oxide deposits.

The central finding was straightforward but consequential: the marks were created using a pigment made from hematite, a form of iron oxide. The results were recently published in the journal Quaternary.

The new case for human intent doesn’t rely only on chemistry. Photographic evidence showed the painted lines were arranged equidistant from each other, “indicating a deliberate and structured pattern,” as the researchers wrote in their study.

From there, the timeline comes with the kind of caution that modern archaeology has to use. The analysis suggests the marks were made at least 17. 000 years ago. but the scientists warned that further study is necessary to definitively determine their age. Still. even if the estimate proves off by a century or two. the study authors say the interpretation of deliberate human action holds: “the horizontal lines (or streaks) represent anthropogenic activity.”.

For Breuil and Sollas, the long debate has narrowed into something closer to vindication. What was once dismissed as natural red staining is now being treated—using the evidence of pigment and pattern—as something closer to art, made by prehistoric people in Wales.

Bacon Hole cave Wales ancient art Upper Paleolithic hematite pigment iron oxide Quaternary journal archaeologists William Sollas Henri Breuil