moss wrote:
Well it could really be to do with the swallowing of water or the disappearance of water over the summer period. There is a Swallowcliffe on Cranbourne Chase where the water disappears, and as tjj says swallet is very common in Somerset. Perhaps it is just a local name.
There's loads of Swallets in Derbyshire, the most famous being Waterswallow falls near Foolow, alternatively named little waterfall Swallet. 