local. [var. SIMMON sb.1] Name for a kind of red shale; also attrib. Symon fault, an interruption of a seam of coal by shale or other material (see quots.).
1834–6. Prestwich, in Trans. Geol. Soc., Ser. II. (1840), V. 432. ‘Symon fault’ … is occasioned by the gradual … substitution of the coal by clay, shale, or sandstone,… the proportion of which rapidly increases, until it entirely replaces the coal.
1839. Murchison, Silur. Syst., I. vii. 101. Even the coal … tapers away and disappears amid the shales and sandstones, constituting what are locally termed ‘Symonfaults.’
1881. Miss Jackson, Shropsh. Word-bk., Symon, a sort of red shale, same as Calaminca, q.v.—Colliery: M[iners’] T[erm].
