Such areas are generally to the south of Southwell where the clay bedrock plateau made up of Mercia Mudstone is dissected by a number of streams, forming steep sided, wooded valleys. This gives a pleasing undulating landscape, locally known as The Dumbles. These areas provide a habitat for Bluebell, yellow archangel, ramsons, dog’s mercury and sweet woodruff. To the southwest of the town there are two dumbles, Halloughton Dumble and Westhorpe Dumble, streams sufficiently large to be labelled Dumble on the 50,000:1 and 25,000:1 Ordnance Survey maps.
The surname Dumble is believed to be of Norman origin and a corruption of the name Donville, a village in Normandy, brought to England by followers of William the Conqueror who came from there.