dumble

A shady valley, a dingle; especially one with steep wooded sides and a stream running through it.

When a stream runs in a deep dell, particularly in clay districts, the steep banks and stream form what are called a “dumble” in Nottinghamshire.

Fine electric activity in sound came from the dumbles below the road, the birds piping one against the other, and water mysteriously plashing, issuing from the lake.

The club rush.

Recently Dr. K. J. Allison has come across a Leconfield lease of 1631 which included 'all the earl 's dumbles growing in Arram Carr' ?

In such circumstances it may well be that a natural pool would be enlarged or deepened or an artificial pond created to maintain a suitable habitat for the rush. Later archival references to the rush “dumbles" are for the River Hull valley.