The area from northern Spain to southern France has long been considered the richest spot for Palaeolithic cave art in the world. Around 150 cave art sites dating from 40,000 to 10,000 years old have been found since the discovery of Altamira in 1879, yet throughout the 20th century only about a dozen caves featuring ancient artwork were found in the Basque country.
     From the time that European caves were first explored in the 19th century, the low density of cave art findings in Basque country  - an important corridor between the continent and the Iberian Peninsula - has been difficult to explain.
     So when Diego Garate and Iñaki Intxaurbe entered the Atxurra cave system in northwest Spain's Basque Country in late 2015, archaeologists had known about the site for over 80 years. But when the two noticed chambers near the high ceiling and started climbing, their lamps revealed the outlines of several previously unknown bison figures.
     Since then, researchers using software to reveal artwork invisible to human eyes have identified 20 more cave art sites in Basque country, nearly tripling the total known for the area. In the rest of Europe, there is perhaps one new find a year; in the Pyrenees - one of the hotspots of cave art - there hasn't been a new find for decades.
     The Atxurra cave system has been visited since at least 1882, and first explored by archaeologists in the 1930s. Now with the help of specially trained cavers exploring high chambers in the deepest areas of the cave, scientists have identified an 11-metre-long panel of art above a narrow platform 4 metres above the floor, with more than 100 engravings and paintings of deer, horses, bison, and goats. Other finds include sharp flints used for engraving the artwork, and the remains of hearths.
     Another Basque country cave the team investigated was hidden below a residential building in the village of Lekeitio. The Armintxe cave's entrance had been covered by rubble in the 1980s, but there was a small entrance hole in a nearby communal garden. Cavers dug this out and climbed inside. In an upper gallery, where the ancient floor had nearly eroded away, they found about 50 engraved animals that had been there for 13,600 to 14,600 years, including two lions - an animal previously seen in cave art in France but never in northern Spain.
     In the well known Aitzbitarte cave system, where the team had previously documented scarce cave art, speleologists found several unknown small chambers containing two bison figures and other animals engraved and then lined in clay - a technique previously documented only in France.

Edited from Sapiens.org (16 January 2018)