Meadow Lark asked after his father and Red Calf gave the message that he should move west where his father was. But the old man said his life was in danger from a man, wife and son who lived in a deep lake over behind a great hill. So Red Calf called to Lightning and all night there was a storm. In the morning the lake was dry and the man, his wife and son lay on the side of the hill. These were the petrified people - the mysterious Rock People. Up to that time they had killed the birds, now the birds scatter out all over the country.

Mythology of the Oglala Dakota, p. 391