It looks a little like something from a slightly rough and ready disaster film. In fact it is a piece of Cornwall tumbling into the Atlantic Ocean, caught by a cameraman apparently out for a clifftop walk. The footage of tens of thousands of tonnes of rock crashing into the sea has been posted on YouTube and is attracting the interest of geologists from around the world.
It is not that such falls are particularly rare but it is uncommon for such clear footage to be captured. The cameraman was on the North Cliffs near Hell's Mouth in north Cornwall when the earth started to move. One woman who is with the cameraman can be heard crying: "Oh My God" as part of the 100 metre high cliff peels away. A man asks: "Are there any people down there?"
Engineering geologist Pete Hobbs of the British Geological Survey said: "That is some of the best footage I've ever seen of a rock-fall." He estimated that about 100,000 tonnes of rock had fallen into the sea. You get something like this once every five years maybe. The chances of catching this on video are incredibly slim: I suspect the cameraman must have noticed something.
"I wonder if he heard some noise or heard some movement before the fall? It is absolutely amazing footage. The action of the wind, the sea, and the ice will break up a rock mass like that and you're losing support for the cliff from below. It's an ongoing process around the coast but it's very, very unusual to catch a large event like that and especially film it. I think geologists around the world will be interested to see it."