For almost a hundred years a monster lurked on Merthyr Mountain in South Wales in the United Kingdom.  It brooded, looking directly down on the small mining town of Aberfan.

And it grew.

From 1875, the Merthyr Vale Colliery extracted coal from Merthyr Mountain.  Spoil from the mining operation, residue, including loose rock and slag, called “tips,” were dumped indiscriminately on the mountainside.  Tips were allowed to build up over highly-porous sandstone and underground springs because it was economically more desirable to dump the waste close to the mining sites rather than carting it off to more remote and safer locations.

The Dowlais Ironworks was founded in the town of Merthyr Tidfil, about four miles north of Aberfan.  It was the voracious appetite of the ironworks that was the cause of Aberfan’s mining operations in the first place.  The demands of Britain’s Industrial Revolution were so great that the population of the area for a time exceeded the total population of Cardiff, Swansea, and Newport combined, the three largest cities in Wales.

And still the monster grew.

In 1963, local authorities raised the alarm, warning the National Coal Board (NCB), the British government entity in charge of running mining operations after Prime Minister Clement Atlee’s nationalization of the coal industry in the wake of World War II.  The NCB discounted the fears of the townspeople about the monster lurking over their town.

And then, the monster struck.

It had rained heavily for several days prior to 21 October 1966 in the Merthyr area.  The monster could wait no longer.

The students of Pantglas Junior School in Aberfan were excited.  It was a Friday, and this would be the last school day before the half-term holiday.  They gathered in the school’s assembly hall for a brief meeting and a singing of the beautiful British hymn, “All Things Bright and Beautiful.”  The students quickly dispersed to their classrooms at 9:15, anxious to get the school day over and done with.

Would that the assembly had lasted just a few more minutes.  For at 9:15, the monster awoke.

Loosened by the torrential rains, more than 150,000 cubic yards of liquefied sludge broke free from Merthyr Mountain and raced downhill.  While 100,000 cubic yards of the sludge stopped its descent on the lower slope of the mountain, around 45,000 cubic yards continued racing downhill and smashed into Aberfan, sluicing through the town in a slurry around forty feet deep.  The slide covered twenty houses on Moy Road, one of three north-south streets in the town, and crashed through the northern wall of Pantglas Junior School.

No one in the town saw the slide until it was upon them, but everyone heard it.  The roar was confusing to many in Aberfan; a number of people thought it was the sound of an airliner about to crash.  Those who finally saw the true nature of the monster could do nothing but stand and watch in horror.  No alert could have been raised in time to save lives.

Despite the efforts of some two thousand emergency workers and volunteers, little could be done to slake the death toll.  The sheer volume of the slag waste, coupled with repeated secondary avalanches, restricted the efficacy of the efforts.

The final death toll of the Aberfan disaster:  144 people.  Of that total, five were teachers and 116 were children between the ages of seven and ten, caught in the jaws of the monster.

The Davies Inquiry, chartered five days after the disaster, sifted reams of evidence and testimony, taking until the following August to render its verdict.  It found that the National Coal Board was solely and entirely to blame for its total lack of a policy to govern the disposal of tips.  The NCB was ordered to pay compensation to the families of the deceased children.

The amount was five hundred pounds per child. about $1200 at 1967 exchange rates.

No member of the NCB staff or board of directors suffered demotion, firing, or prosecution for their culpability.