Ed Yong in The Atlantic:
In February 1990, thanks to a 15-year-old boy named Bruno Kowalsczewski, footsteps echoed through the chambers of Bruniquel Cave for the first time in tens of thousands of years.
The cave sits in France’s scenic Aveyron Valley, but its entrance had long been sealed by an ancient rockslide. Kowalsczewski’s father had detected faint wisps of air emerging from the scree, and the boy spent three years clearing away the rubble. He eventually dug out a tight, thirty-meter-long passage that the thinnest members of the local caving club could squeeze through. They found themselves in a large, roomy corridor. There were animal bones and signs of bear activity, but nothing recent. The floor was pockmarked with pools of water. The walls were punctuated by stalactites (the ones that hang down) and stalagmites (the ones that stick up).
Some 336 meters into the cave, the caver stumbled across something extraordinary—a vast chamber where several stalagmites had beendeliberately broken. Most of the 400 pieces had been arranged into two rings—a large one between 4 and 7 metres across, and a smaller one just 2 metres wide. Others had been propped up against these donuts. Yet others had been stacked into four piles. Traces of fire were everywhere, and there was a mass of burnt bones.