42, GEOLOGY OF SHROPSHIRE. 
greater antiquity of the former is derived from fossils. Here, however, 
the two formations are separated by a fault, which must be of consider- 
able throw, since, as I have reason to believe, neither the upper part of 
the shales nor the lower part of the sandstone is represented. Following 
the shales on the line of strike to the north-east into the ravine between 
the Lawley and the sandstone escarpment of Hoar Edge, where the 
escarpment approaches to within a quarter of a mile of the hill, we find 
them well exposed on the stream, dipping to the east at an angle of 50°, 
which probably represents the true dip more accurately than the shallow 
road-section. I have detected in them Lingulella Nicholsoni and Shineton 
Graptolites. From their general appearance, and from the presence of 
Graptolites, I infer that these beds belong to the middle part of the series. 
There are slight indications, in the shape of the ground and in the soil, 
that the shales run parallel to the Hollybush towards the south-west, 
where both are cut off by the Hoar Edge Grits (Caradoc.) 
(c.) Cardington sub-area.—A little over a mile from Caer Caradoc to 
the south-east is an abrupt ridge of quartzite called the Sharp Stones, 
dipping to the north at from 40° to 50°, and striking east and west for 
about half a mile. It rests upon the bedded volcanic rocks of Cardington 
Hill, and is evidently tilted up by the elevation of that mass. Succeeding 
it to the north is Caradoe Sandstone, with its usual south-west strike, 
apparently unaffected by the upthrust of the older rocks, and probably 
separated from the quartzite by a fault. 
2.—RELATIONS OF THE QUARTZITE TO THE ASsocIATED Rocks. 
Along the south-easterly flanks of the Wrekin range the quartz rock 
rests upon the bedded tuffs and felstones of the volcanic nucleus 
unconformably, the igneous rocks dipping north, while the quartzite dips 
south-east. Towards its base the quartz rock contains fragments 
derived from the older series, consisting of small rounded or unrounded 
pieces of felstone greatly decomposed, but in some cases showing 
distinctly the banded structure characteristic of some of the Wrekin 
felstones. At its base the quartzite is brecciated, both the fragments 
and their cement being quartzose, with the occasional occurrence of 
barium sulphate. This breccia can be ‘traced along the line of junction 
through the Ercal, Lawrence Hill, and some distance along the south- 
eastern flank of the Wrekin. There are also signs of brecciation on the 
cpposite side of the range, near the ravine between the Hrcal and 
Lawrence Hill. This breccia may be a friction breccia, caused by the 
upthrust of the rigid mass of volcanic rock which forms the backbone of 
the range ; and the fact that the breccia is not derived from the rockupon 
which it rests favours this conclusion. There is thus reason to conclude 
that the plane of junction between the younger and older series is a fault. 
In my paper on the Shineton Shales, I have given reasons for 
concluding that the quartzites are also separated from the overlying 
Hollybush Sandstone by a fault. See Quarterly Journal Geological Society, 
Vv. Xxxiil., p. 662. 
3.—THE AGE OF THE QUARTZITES. 
The quartzite is certainly older than the Hollybush Sandstone, for, 
in every observed case, the sandstone rests upon the quartz rock, or is at 
