Shilf

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.

Two loads of clay, and one load of coarse shilf mixed and wetted, and trodden together to lump […]

Reet is that shilf we have on older houses here. They do take it off sometimes and change to new.

Below the statum of tin ground is a bed of stiff clay called shilf or shale.

So, too, will shilf, the name given to the little pieces of waste slate which are abundant in Cornwall: one part of shilf to two of mud and straw was the usual recipe for 'clob', as the Cornish often called it.