A clue is that prior to being published in 1865 "Alice in Wonderland" was originally called "Alice's Adventures Underground". It has been proposed that the inspiration for the story relates to a natural geological feature of the region, in particular gypsum subsidence.

Charles Dodgson (Lewis Carroll) spent his early youth at nearby Croft. He would have been familiar with "Hell's Kettles" three ponds which according to legend were bottomless. (Actually they are only about 7 metres deep!).

Later on the family moved to Ripon an area troubled by gypsum subsidence which often resulted in the sudden appearance of large holes in the ground. Two such holes two years ago (c1997) destroyed several properties and led to the evacuation of a number of houses including Ure Lodge, used by Sir John Tenniel for the illustrations of the first edition of Alice in Wonderland.

At a British Association Science Festival, Dr. Cooper of the British Geological Survey noted that "Lewis Carroll was almost certainly aware of the problems. He would have seen the collapses in his friends' gardens and the numerous collapses in the fields opposite Ure Lodge".

See also Jenny's Lewis Carroll related blog