It was a heartbreaking tragedy known across the world by the name of the South Wales village where it happened: Aberfan. On this day millions of cubic metres of excavated mining debris came thundering down a hillside, engulfing a farm, several houses – and Pantglas Junior school, where 116 young children died.
In those days big lump coal was required for domestic heating so the waste and tailings – fine particles left after the washing process – was loaded onto rail trams and dumped. Every mining community had its tips. The entire South Wales landscape was jagged with them. And for years this waste material had been piled high above Aberfan. The tips were notorious for sliding but there was particular concern about Aberfan’s Tip Number Seven which was started in 1958 and by 1966 amounted to 230,000 cubic metres of waste rising 111ft (34m).
In the previous year two mothers had presented a petition to the school's head teacher Ann Jennings about flooding concerns caused by Tip Number Seven. Mrs Jennings took the petition to the local council but no action was taken.
It was later discovered that the mountain of coal waste lay on highly porous sandstone riven with streams and underground springs.
At 9.15am on a foggy October 21, 20ft of material from Tip Number Seven, swollen by heavy rain, became dislodged, starting a landslide of slurry and debris that thundered down the hillside. Below, excited children had congregated for morning assembly at their school knowing the half-term holiday would begin at midday. Their daily rendition of All Things Bright and Beautiful – a hymn written just a few miles away – was postponed because Mrs Jennings had decided they would sing it before they went home when she planned to wish her pupils a safe and enjoyable holiday. Just before 9.15am they heard a strange rumbling noise. One teacher said it was probably thunder. In fact a 30ft wave of coal, mud and water was heading for the school. Already it had engulfed a farm cottage in its path, killing all the occupants. Survivor Gaynor Minett, an eight-year-old at the school, remembered four years later:
"It was a tremendous rumbling sound and all the school went dead. You could hear a pin drop. Everyone was petrified, afraid to move. Everyone just froze in their seats. "I just managed to get up and I reached the end of my desk when the sound got louder and nearer, until I could see the black out of the window. I can't remember any more but I woke up to find that a horrible nightmare had just begun in front of my eyes."
The slurry had piled up 25 feet (7.6m) against the school, smashing its way through the building, filling the classrooms. Hours later, one of the first journalists on the scene was a reporter from the local Merthyr Express. He wrote: "Men, women and children were tearing away the debris in an effort to reach the trapped children. As the men shovelled debris from spade to spade, children’s books appeared. An odd cap was seen. A broken doll. "Mothers gathered around the school steps, some weeping, some silent, some shaking their heads in disbelief. "Teams of men and boys worked in long rows from the school building, handing buckets of slurry from the classrooms." By the next day, the Merthyr Express reported, on each side of the school mechanical shovels and bulldozers gouged the debris out. An endless line of lorries carried it away. The report continued: "At regular intervals everything would come to a halt – the roar of heavy machinery, the shouts, the scraping of shovels. Not a murmur would be heard among the thousand workers. Time stood still. And rescuers listened tensely for the slightest sound from the wreckage – for a cry, a moan, a movement – anything which would give hope to the mothers and fathers." Everybody wanted to do something. Hundreds of people from other villages drove to Aberfan to try and help with the rescue. It was futile; the untrained rescuers merely got in the way of the trained rescue teams. Nobody was rescued alive after 11am on the day of the disaster and it was nearly a week before all the bodies were recovered. They included the head teacher Mrs Jennings and her deputy, David Beynon. "He was clutching five children in his arms as if he had been protecting them," a rescuer said. Just 25 pupils at Pantglas survived. The final death toll came to 116 children and 28 adults, including five teachers. At the time of the disaster, there were about 100,000 miners in south Wales, an area which relied heavily on the coal and steel industries. Today there are just a few hundred miners left.
Most of the pits – like Merthyr Vale colliery, which produced the Aberfan slag heap – have been "landscaped". One has been turned into a museum. The site of Pantglas Junior school has been turned into a memorial garden, overlooked by carefully maintained white arches, one for each of the 116 children who were killed by the avalanche and who were buried here in a mass grave.