shilf

noun2

1. •
   (dialect) Coarse shale or slate fragments.

   • Below the statum of tin ground is a bed of stiff clay called shilf or shale. — 1808
2. •
   (no longer used) straw or reeds.

   • Five-and-twenty of them are tied together and laid at the depth of one fathom at most on sunk posts, as the sevrugas go to shallow places and among the shilf. — 1800