The thin plate of iron used in Scotland for the manufacture of oaten cakes is called a “girdle,” for which Culross was long celebrated.
“Locks and bars, plough-graith and barrow-teeth! and why not grates and fireprongs, and Culross girdles?” —Scott: Fair Maid of Perth, chap. ii.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894