Mining. Also warren. [Of obscure origin; perh. a use of prec.] Under-clay.
1847–89. Halliwell, Warrant, the bottom of a coal-pit.
1871. A. H. Green, Coal (Manch. Sci. Lect., Ser. II.), 5. I think in Lancashire that you know it [the under-clay] by the name of ‘warrant,’ or ‘seat earth.’
1883. Gresley, Gloss. Coal-mining, Warrant; Warren or Warren Earth.
