406 PUOF. J. F. ULAKK ON THE M ONI AN AND 



roads to Ragleth Wood and Hazier, over a horizontal breadth of 

 2000 feet. Further north, on the road from Church Stretton to 

 Caer Caradoc, they are exposed with their usual dip and strike be- 

 neath the Drift ; and on the southern slopes of Caer Caradoc, they 

 occupy a band running transverse, and almost perpendicular, to the 

 line of fault. All these exposures being to the east of the fault, it 

 is obvious that this last has no connection here with the relations 

 of the dark shales to the igneous rocks, and we cannot solve 

 the question by saying that the junction is a faulted one. It does 

 not, of course, follow that the great fault is the only one ; indeed, 

 we know that there are several others on the N.E. side of Caer 

 Caradoc, and the whole area on the eastern side of the main fault 

 is greatly disturbed and dislocated. This fact is of use in accounting 

 for certain difficulties, but will not solve the question as to the 

 relation of the rocks before they were locally faulted. 



Eliminating, therefore, the influence of the main fault, we must 

 now inquire into the relative age of the adjacent volcanic group and 

 dark shales. If the dark shales be the younger, and are merely dis- 

 placed by local disruptions, we ought somewhere to find their basal 

 beds. They are not at all the sort of rock to show basal beds or to 

 be derived from volcanic debris — indeed the actual result of the 

 denudation of the rhyolites is seen in the Longmynd conglomerates. 

 There are indeed grits and conglomerates which may be considered 

 basal on these hills, but their relation to the igneous rocks and 

 shales is nowhere such as to indicate that they lie between them, being 

 usually found remote from the junction, so that they are the basal 

 beds of another formation. On the other hand, if the volcanic 

 rocks be the younger, however much clastic material they may 

 contain, they must somewhere break through the dark shales and 

 alter them. The very faulting of the district would make the con- 

 tacts scarce, and mingle up adjacent rocks confusedly. Yet almost 

 all the puzzling rocks, that may be either altered slate or banded 

 compact lava, are found at the lines of junction, and each one ex- 

 amined with the microscope has turned out to be a slate. 8uch 

 rocks are Aveil seen on the north-eastern slope of Ragleth. Their 

 bedding is here across the hill, and makes an angle of quite 45° 

 with the normal strike of the slate. This is only natural, if it be 

 pushed aside, as it must have been, by the igneous rock. 



From Hazier Hill Ave can learn nothing, as there is only dolerite 

 in it, which may be of later date ; but Helmeth is full of interest. 

 All along the lower path on the western side we walk on slightly 

 altered slate ; but along the crest we find the southern half is all 

 rhy elite, and the northern half yields successive exposures of rhyo- 

 lite, slate, and dolerite. The boundary of the slate must there- 

 fore zigzag amongst the igneous rocks, and in fact at one spot a 

 coarser rock than usual, almost like a eurite, is seen intruding into 

 a true slate. Most of the southern slopes of the hill are also 

 occupied by slaty rocks. The character of these slates does not, 

 indeed, remain absolutely constant, but there are bands of hard 

 greywacke, seen at Hazier, and inferred from fragments here. 



