Thomas McKenny Hughes

“ Following up the stream by Penycae to the south-east, about one third of a mile south-east of Penycae we find some crushed Sandstone in the bed of the stream, but no clear section. If we proceed straight on, climbing the hill on the north-east of the gully, we soon come upon a long line of fragments of white Grit, nowhere seen in place, but, as far as it can be traced, keeping a uniform distance from the Pale Slates, as if they were portions of a rock broken up along its outcrop. ”

“ The beds below the Grits are, as a rule, bluish rab, i. e. a shivery mudstone breaking along bedding, joints, and imperfect or double cleavage into irregular, often somewhat prismatic fragments. Frequently, however, these beds have, especially where much weathered, a pale grey colour, much resembling that of the beds above the Grits. This may perhaps be because they are derived directly from the felspathic ash of some volcanic district, while the Silurian beds above the Grits have been formed later on from the waste of such beds. ”

“ In Nant Llechog the Grit is represented by a white saccharoid sandstone, sometimes ripple-marked and false-bedded, sometimes with black lines and bands of slate in it, at others quite homogeneous. In several places along this line of outcrop I noticed in the Bala beds a kind of double cleavage, to be referred to two successive movements causing lateral pressure, not in the same direction, and giving to the rock, when viewed across the broken edges of the cleavage-planes, an elongated lozenge-shaped structure. In the series overlying the Grit there seemed to be but one cleavage. ”