1) A deep hole or opening in the ground.
The word has a very long history and is now associated particularly with landscape features in limestone country. Less obviously it was used when the piers of bridges had their foundation timbers swept away by the scouring action of the water: 1705 wanting Twenty Four yards of Oake frameing under the Swallow att the south end, Newton Bridge over the Hodder. Such holes or pits were formed by the whirlpool action of the water: 1673 late greate flood ... the stones that fell downe being driving [sic] away into deepe turnepitts not to be recovered, Bolton Bridge. Usually, the reference is simply to ‘holes’. In 1686, John Rhodes of Harden agreed to fill up and Sett with stone A great hole worne by the River under the East bow of Kirkstall Bridge: it was 15 yards long, 8 yards wide and 4 yards deep, and had been there so long that it was called the Fowle hole.