WENLOCK LIMESTONE IN RADNORSHIRE. 



313 



Course of the Wenlock Limestone in Radnorshire. 



Between the limestone of the undulating hills of Lingen and the next point where 

 that rock re-appears to the south-west, is the broad denudation around Presteign ; but to 

 the south-east of the town rises a sharp low ridge extending into the Nash Scar. On 

 the north and south-east this ridge is flanked by a limestone identical in position and 

 organic remains with that of Wenlock. Another depression succeeds to the south-west 

 of this ridge, and the limestone is again lost, but it re-appears on the flanks of the trap 

 hills 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 the 

 contiguous trap rocks, they will be described in the following chapter. I shall here 

 mention only a few facts connected with the development of the limestone and its 

 organic remains. 



Haxwell. Nash Scar. 



52. 



At the north-eastern termination of the Nash ridge, some beds of the Wenlock shale with nodules 

 and 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 in 

 the 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 also 

 met with. This patch of limestone and shale is disconnected from that of the Nash Scar by the 

 protrusion of certain underlying grits of the Caradoc sandstone j but even in the great amorphous 

 masses of limestone in the Scar, a* of wood-cut, we again find several of the well-known fossils of 

 the formation, such as Productus lepisma (Dalman), Nerita spirata, and large steins of Crinoidea. 

 Besides these fossils, including Orthoceratites, Mr. Edward Davis 1 has discovered one specimen of 

 the 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 most 

 abundant in the accompanying shale at the north end, and towards the south-western end of the 

 calcareous cliff, where the lines of stratification are best seen, and particularly on the sides of the 

 quarries at Haxwell a a, where a bulging mass of the limestone distinctly bedded is thrown off both 

 sides of a nucleus of the quartzose grits of the Caradoc sandstone b, as represented in the above 

 wood-cut. The unaltered or slightly altered portions of the limestone are brownish, subcrystallme, 

 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 2 ." 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 valuable 

 assistance. 



9 The basalt of the Clee Hills is also called Jew stone, p. 126, and the same name is applied to hard quartzose 

 altered coal sandstone near Kinlet, p. 167. This quarriers' term is, therefore, evidently used to designate all 

 hard unmanageable rocks of uneven and splintery fracture, whatever may be their colour and composition. 



