CHAPTER XVIII 



SILURIAN SYSTEM (continued). 



Lower Silurian Rocks, 



Caradoc Sandstone and Llandeilo Flags. 



3rd Formation Caradoc Sandstone, g, h, i, h, of wood-cut, p. 196, Sections, 



PL 31. figs. 3 and 4. 



As the overlying formations of Ludlow and Wenlock occupy separate parallel ridges , 

 divided from each other by a longitudinal valley, excavated in the lower Ludlow rock ; 

 so the strata of this formation rise from a valley in the Wenlock shale and constitute 

 a third ridge, parallel to those already described. The name has been selected, 

 because the strata of which it is composed constitute a number of eminences, which 

 abut against the remarkable chain of trap hills called the Caradoc, as represented in 

 the opposite lithographic sketch, a. The Ludlow rocks. 6. The Wenlock limestone, 

 c. The Caradoc sandstone rising up in the hills described, and resting upon the trap 

 rocks (r 1 ) of the Caer Caradoc and (r) Lawley. The Wrekin appears in the distance 

 (r"). The remote country is occupied by New Red Sandstone and coal measures. 

 The villages of Kenley, Church Preen, Acton Burnell, Hope Bowdler, and Acton Scott 

 are built upon these rocks, and their various beds are traversed, in passing from the 

 valley on the west of Wenlock edge to the flanks of the Caradoc chain. Instructive 

 sections may also be observed in crossing the south-western extension of these hills 1 , 

 at several points between Acton Scott and Cheney Longville. The clearest of these 

 sections is that exposed upon the banks of the Onny, between Wistanstow on the south- 

 east, and Horderly on the north-west. Where not much dislocated, the uppermost 

 strata dip to the south-east at angles of eight to ten degrees, the inclination of the 

 lower strata increasing to thirty-five, forty, sixty degrees, and even to verticality, as 

 they approach and come into contact with the trap rocks, or lie upon the anticlinal 

 lines marked by the prolongation of the Caradoc ridge. 



Unlike the mudstones of the upper Silurian rocks, this formation is composed essen- 

 tially of sandstones of different colours, with an occasional subordinate course of cal- 

 careous matter. To convey a correct notion of the nature and succession of the strata^ 



1 These hills are from 500 to 800 feet high. 



