The Aberfan disaster was a catastrophic collapse of a colliery spoil tip in the Welsh village of Aberfan, near Merthyr Tydfil, on 21 October 1966, killing 116 children in the school and 28 adults. It was caused by a build-up of water in the accumulated rock and shale, which suddenly started to slide downhill in the form of slurry
The Longyou Caves were only discovered late in the 20th century. At least 24 caves have been discovered so far. All of which were carved by hand. Although the overall excavation involved almost a million cubic metres of stone, there is no historical record of them or evidence of the work. Their origin is a complete mystery. At present there is no explanation for their existence. They represent one of the largest underground excavations of ancient times.
On 21 October 1966, after several days of heavy rain, 40,000 cubic metres of debris from a colliery waste tip broke away and slid downhill towards the Welsh village of Aberfan. The catastrophic landslide hit the local junior school, killing 116 children and 28 adults. http://www.britishpathe.com/video/this-is-tragedy
Well, to actually help the OP, one tonne will cover approximately ten square metres at 50mm thick. That goes for pretty much all common materials, except soil which is much lighter per cubic metre. Oh, and those bulk bags are approx. half a cubic metre, or one tonne. We used to put a tonne in each, but we started to see our sales drop, so we acquired bags from all our local competitors, and weighed them. The amounts in some were, quite frankly, embarrassing, given that most of the local…