Page:VCH Herefordshire 1.djvu/69

 GEOLOGY collected from all parts of the county it was found that the percentage of carbonate of lime varied from 38 to 88. Both De la Beche" and McCullough °' thought that the cornstones were formed from carbonate of lime deposited from a chemical solution. The fish-remains in the Lower Cornstones of Ewyas Harold Common are usually only fragmentary, but a fine example of Eucephalaspis Agassizt, Lankester, has been obtained, and it was here that Dr. McCullough found the gigantic Pterygotus taurinus^'^ which must have measured when perfect no less than seven feet. A peculiar fossil not infrequent here and in other parts is the Parka decipiens — the egg- packets of Pterygotus. Above the Lower Corn- stones are the Rowlstone Beds, such as cap Rowlstone Hill. Formerly they were quarried near the church, and yielded the Stylonurus Symondsi^'^ and the giant isopod, Praearcturus gigas.''^ From certain ' red flaggy beds ' associated with the Lower Cornstones in the Black Mountains between Hay and Cusop, Symonds obtained the largest known fish-spine from the Old Red. It was called Onchus major by Etheridge. On the hill above Cusop are beds, on about the same horizon as the Rowlstone Beds, so rich in plant-remains that they suggested a search for coal, but vestiges of the old workings on the eastern side of the ravine above the village alone commemorate the fruitless attempt. Cornstones and sandstones prevail in the Golden Valley district, and in the neighbourhood of St. Weonards. Cornstones are worked beyond Kilpeck, at Kentchurch, and on Orcop Hill, at all of which localities fish- remains have been found. These hills, together with Saddlebow, are capped with the Rowlstone Beds. In the neighbourhood of Ross, although sections are not infrequent, the Old Red Beds have received scant attention. Symonds said he searched all the quarries and railway-cuttings in the vicinity, but failed to find any traces of fossils.''^ De la Beche has given a record of the succession of the beds between Howie Hill, near Hope Mansel, and Welsh Court, on the flanks of the Woolhope inlier near Yatton Chapel, placing the total thickness of the beds at 5,620 ft." The Old Red rocks around Hereford, Weobley, Leominster, Bromyard, and between Ledbury and the Woolhope inlier of Silurian Beds, all belong to the Lower Division. In most places denudation, eff^ected principally by rain and rivers, has scooped out valleys and left intervening hills. These hills are generally formed of the Lower Cornstone, capped in many cases with sand- stones (Rowlstone Beds) from which not infrequently the Brownstones have only recently, geologically speaking, been removed. Hills composed mostly of cornstones rise up on all sides of the county town. Such are Dinmore, The Pyons, Aconbury, Dinedor, Tyberton, Moccas Hill, and Credenhill — the last being that bold wooded eminence which rises to the north of the Roman Magna Castra, the present Kenchester. " Mem. Geol. Surv. i (1846), p. 52. " Trans. IToolhfe Nat. F.C. 1868 (1869), pp. 8-1 1 ; ibid. 1869 (1870), p. 36. ^ Ibid. 1869 (1870), p. 38 ; Re/>. Brit. Assoc. Norwich (1868), p. 78. ''" Edin. New Phil. Joum. vi (1857), p. 267 ; Quart. Journ. Geol. Soc. xv (1859), p. 230 ; ibid, xxi (1865), p. 426 ; Trans. Woolhope Nat. F.C. 1868 (1869), p. 239. " Quart. Journ. Geol. Soc. xxi (1865), p. 484 ; Trans. Woolhope Nat. F.C. 1870 (1871), pp. 266-70. " Flora of Herefordshire (1899), p. vii. " Mem. Geol. Surv. i (1846), pp. 55-7. 21