174 OLD RED CONGLOMERATE AND SANDSTONE IN SHROPSHIRE. 



rocks, whilst strata of the underlying Silurian system, formerly termed greywacke, so far 

 from assuming an air of higher antiquity, in numberless cases and over very large areas, 

 resemble closely some of the younger secondary deposits. 



The lower portion of this upper sandstone, caps the escarpment of the corn stone and marls both 

 in the splendid mountain range of the Black Forest, and in the central parts of Herefordshire, ap- 

 pearing as thickly bedded sandstones of excellent quality for building, and is quarried for tiles in 

 the hills south of Hay, as well as to the south-east of Weobly. In most other parts of Hereford- 

 shire, the upper sandstones thin out, the underlying cornstones rising to the surface \ but in the north- 

 eastern parts of the county, particularly round Bromyard, there are also sandstones which come within 

 this division of the system. The finest examples occur in the large quarries of Bromyard Downs, on 

 the road to Worcester, where there are light-coloured, slightly micaceous, finely grained, whitish or 

 greenish sandstones, in beds of 6 and more feet thick, separated from each other by courses of deep 

 red marly clay, and divided by vertical fissures partially filled with it. These quarries produce 

 blocks of stone 20 feet long by 6 feet wide, and troughs of great depth. The cap of the rock consists 

 of flaggy incoherent beds of a dingy red colour, with spots or blotches of greenish argillaceous 

 marl. Whitish sandstones resembling those of Bromyard Downs, and of excellent quality, are 

 quarried near Cleobury Mortimer, and others of red colour are extracted in large masses for cider- 

 presses, in the range of the hills north of the Teme near Pensax. These strata alternate with marls 

 and other sandstones, which are hard, flaglike, and micaceous. 



In that district of Shropshire which environs the coal-field of the Forest of Wyre, and 

 extends to the neighbourhood of Bridgenorth and Wenlock, the upper member of the 

 Old Red Sandstone is generally ill exhibited, the only clear and unequivocal section of 

 it being that which is exposed at Prescot Bridge and Oreton. (See PI. 30. fig. 1 .) Without 

 the plainest evidence of superposition, this soft yellow sandstone might be mistaken for 

 a coal-measure stratum, but as it is really overlaid by a quartzose conglomerate, which 

 dips conformably beneath a band of true carboniferous limestone, and on the other hand 

 reposes on cornstone, all doubts are dispelled, and like rocks of similar composition 

 and colour which we shall hereafter notice in Pembrokeshire, the yellow sandstone of 

 Prescot Bridge, is thus proved to belong to the upper division of the Old Red System. 



Similar geological relations are displayed on the steep acclivities of the Clee Hills. 

 The southern extremity of the Clee-barf (the Brown Clee,) is strongly marked by the 

 exposure of the upper conglomerates and grits, though in some parts they are so grey 

 as to resemble the overlying millstone grit. The upper beds of the Old Red here 

 conform to the lowest sandstone of the coal measures, both being inclined at small 

 angles, and affected by the same faults and dislocations. (See Chapter VIII. pp. 123 

 and 124, and PL 30. fig. 6. ; and PI. 31. figs. 3 and 4.) 



These beds are less clearly exhibited on the slopes of the Titterstone Clee, except in 

 the western face of the Knowlbury field, to the south of which, being much attenuated, 

 and also thrown up at very high angles, they occupy only a small surface. In all these 

 cases, the strata of this group dip under and support (conformably) the carboniferous 

 strata, as in the escarpments of the coal basins of South Wales and the Forest of Dean. 



