What sort of geological formation housed a clan that was responsible for the murder of over 1000 people in Scotland between the 13th and 16th centuries?
Bennane Head:  A 200 m cave near Bennane Head is said to be the place, where the cannibal Sawney Bean and his family lived in the 15th century. Sawney Bean: Alexander "Sawney" Bean was said to be the head of a 48-member clan in Scotland anywhere between the 13th and 16th centuries, reportedly executed for the mass murder and cannibalisation of over 1,000 people.
i don't know