According to the canal guide I use, the Caldon Canal is called that as, in the original Canal Enabling Act - giving permission to build the canal, there was a spelling mistake. It should have been "The Cauldon Canal". A major canal cargo was limestone from Cauldon Quarries to Froghall (via crude railway), then out on the canal.
However our local historian advises "Cauldon was spelt both with and without the 'u' in Church records as far back as the late 1600s. Maybe more of a spelling choice than a spelling mistake? Similarly Alveton/Alton - there was no point where the name officially changed"