It was a vague sound at first, like the noise you hear when you're standing on a bedroom floor and the central heating comes on. (Or, if it's anything like mine, if it comes on. Mind you I haven't got central heating so it wouldn't would it). It was an obscure and distant rattle, the sort that makes you look round and go, 'ooh wassat?'
It very quickly got a lot louder. Within moments the noise was almost deafening, made worse by the proximity of the walls surrounding them as the sound waves were thrown back at the ship, rebuffed by the impenetrable rock.
Then the crew began to hear cracking and grinding. It was as if someone were tearing a giant, crusty loaf of bread in half.
It steadily got louder and louder until someone shouted “LOOKOUT!”
A boulder the size of a rhinoceros had broke
