Source : Webster's Revised Unabridged Dictionary (1913)

Delf \Delf\, n. [AS. delf a delving, digging. See {Delve}.]
   A mine; a quarry; a pit dug; a ditch. [Written also {delft},
   and {delve}.] [Obs.]

         The delfts would be so flown with waters, that no gins
         or machines could . . . keep them dry.   --Ray.

Delf \Delf\, n.
   Same as {Delftware}.

Source : WordNet®

delf
     n : an excavation; usually a quarry or mine