BASAL CAxMBKIAX ROCKS OF SHROPSITIRE. 



::J95 



the purple grit, all are of banded greywaokcs. This shows first 

 that the outlier is here at its end, and secondly that it lies, not upon 

 No. 5 but upon 'No. 4 of the older scries. In this locality, on the 

 S.E. of Narnells rock the actual junction of the purple grit with 

 the underlying rocks is seen (see fig. 4). This line of junction has 



Fig. 4. — 27ie Junction of ,S I ate and Grit Sovth of NcmuUs llocJc 



here itself a dip towards the west of about 75°, showing that tlie 

 outlier is more or. less folded in with other rocks. The surface is 

 somewhat slickensided, and the line is slightly irregular and cuts the 

 edges of the underlying slates very obliquely. This grit is therefore 

 here seen to lie un conformably, but the evidence is scarcely satis- 

 factory or conclusive. If it had been conformable, the motion 

 which is indicated by the slickcnsides might easily have produced 

 the amount of unconformity apparent. 



The eastern boundary of this outlier can be fairly well traced, 

 but the western which runs across heath-covered moorland is en- 

 tirely conjectural. But in the next depression we get its southern 

 termination, and the same phenomena are repeated. Here in Cal- 

 low Hollow, as before, if attention is confined to the stream-section 

 where almost every yard of rock is exposed, we find nothing but a 

 succession of bedded slates and greywackes, with the usual constant 

 dip and strike, carrying them straight across the valley, but the 

 moment we climb the slopes we come upon conglomerate. On the 

 northern side this may be traced in a horizontal line trending S.E., 

 each exposure facing a different rock in the series below. Ou the 

 southern side the same thing is observable. So too in the next hol- 

 low to the south, /. e. !Minton Batch, the boundary of the purple grit, 

 some of which has the pui'ple-slate fragments, follows the contour 

 of the country, but the purple slates below are vertical and cross 

 the valley. If there is such a thing as local field-evidence for an 

 unconformity, I think we have it here. 



Passing still to the south, wo find ourselves approaching the 

 western slopes of the Longmynd proper, and no more dependent on 

 stream-sections and valley-sides. As soon as we descend these 

 slopes we come again upon purple slates and greywackes, and the 

 line of junction is seen to rise gradually towards the south, so that 



