WENLOCK LIMESTONE IN RADNORSHIRE.Course of the WenlocJc Limestone in Radnorshire.

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Between the limestone of the undulating hills of Lingen and the next point wherethat rock re-appears to the south-west, is the broad denudation around Presteign ; but tothe south-east of the town rises a sharp low ridge extending into the Nash Scar . Onthe north and south-east this ridge is flanked by a limestone identical in position andorganic remains with that of Wenlock. Another depression succeeds to the south-westof this ridge, and the limestone is again lost, but it re-appears on the flanks of the traphills of Old Radnor. There the band of Wenlock limestone is much broken, contorted,and in parts highly altered; but as these phenomena are intimately connected with thecontiguous trap rocks, they will be described in the following chapter. I shall heremention only a few facts connected with the development of the limestone and itsorganic remains.

Haxwell. Nash Scar.

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At the north-eastern termination of the Nash ridge, some beds of the Wenlock shale with nodulesand two thin courses of limestone are thrown off the inferior strata at angles (dipping 50° N.N.E.).The limestone here is foetid and highly argillaceous. Corals similar to those at Wenlock occur inthe way boards of shale, and in the surface of the limestone Asaphus caudatus, Calymene variolaris,Calymene macrophthalma, Isotelus (Bar Trilobite), &c., and other characteristic fossils are alsomet with. This patch of limestone and shale is disconnected from that of the Nash Scar by theprotrusion of certain underlying grits of the Caradoc sandstone; but even in the great amorphousmasses of limestone in the Scar , «* of wood-cut, we again find several of the well-known fossils ofthe formation, such as Productus lepisma (Dalman), Nerita spirata, and large stems of Crinoidea.Besides these fossils, including Orthoceratites, Mr. Edward Davis 1 2 has discovered one specimen ofthe Pentamerus Knightii in this limestone, the only exception to the rule which I have laid down,that this fossil is peculiar to the Aymestry limestone. These fossils are, however, found mostabundant in the accompanying shale at the north end, and towards the south-western end of thecalcareous cliff, where the lines of stratification are best seen, and particularly on the sides of thequarries at Haxwell a a, where a bulging mass of the limestone distinctly bedded is thrown off bothsides of a nucleus of the quartzose grits of the Caradoc sandstone b, as represented in the abovewood-cut. The unaltered or slightly altered portions of the limestone are brownish, subcrystalline,and bituminous. They are convertible into lime with a less quantity of coal than the hard crystal-line unbedded limestone a*, called by the workmen “Jew stone®/’ However obscure in the larger

1 Mr. Edward Davis is son of my friend Dr. Davis of Presteign, to whom I am indebted for much valuableassistance.

2 The basalt of the Clee Hills is also called Jew stone, p. 126, and the same name is applied to hard quartzosealtered coal sandstone near Kinlet, p. 167. This quarriers’ term is, therefore, evidently used to designate allhard unmanageable rocks of uneven and splintery fracture, whatever may he their colour and composition.