Siltstone,medium dark grey to grey brown, 20-30% argillaceous matrix, 0-5% calcareous, trace-5% glauconite, 0-trace micromica, trace pyrite, trace calcite crystals, soft to firm, blocky. Minor interbedded sandstone, light to medium grey, very fine grained, well sorted, subangular to rounded, 30% silt matrix, 10% calcareous cement, trace-10% glauconite, poor visual porosity, firm. Minor interbedded limestone, white to light grey, light brown, 0-20% silt, trace calcite crystals, microcrystalline, no visual porosity, firm to hard.