392 PROF. J. F. BLAKE ON THE MONIAX AND 



thus appears as an outlier. The eastern portion of this is composed 

 of mixed masses of purple-weathering slate and purple grey wacko, 

 very much in the same way as jN'o. 5, whose strike it continues and 

 to which it is referred. Several miles to the ]N"orth-east is the small 

 inlier of Pitchford, surrounded by basal Carboniferous rocks. This 

 inlier is exposed aloug a stream, and consists of well-bedded ver- 

 tical glistening purple slates with hard greywacke bands. It is 

 not remarkably like any of the subdivisions ; but of all of them it 

 is most like the banded series whose line of strike it continues. 

 Purther North still, but more to the West, stands the great inlier of 

 Haughmond Hill. Dr. Callaway has shown that the long line of 

 " greenstone " marked on the Survey map is really a conglomerate ; 

 the rocks to the East of the line consist mainly of hard grey wackes, 

 but with occasional masses of pale slate. These alternations and 

 bedding are well seen in a quarry on the eastern slopes, where the 

 rocks are more micaceous than usual. This series represents jSTo. 5 

 extremely well ; and, as in the Longmynd and by Smethcott, is 

 easily confounded with the overlying rocks. 



2. The Junction-line between the two Series in the Longmynd. — 



"We now pass to consider the junction of this lower series 

 of five groups with the conglomerates and grits which form the 

 upper part of the Longmynd massif. This is one of the most critical 

 matters in the whole question. As just noted, we may often think 

 we see a passage from one to the other, and if without due care we 

 assign an isolated exposure of purple grit to the overlying beds in- 

 stead of to No. 5, we may well believe they are interbedded. 



The first point to be noted is that the great conglomerate, which 

 lies towards the base of the upper series, seldom forms the actual 

 basal bed, there is almost always a mass of reddish-purple grit below 

 it (see figs. 1, 2). The true basal bed seems to be that referred to 

 by Sir E. I. Murchison, as containing small masses of purple slate. 

 These, usually about h inch in diameter, are angular and very dis- 

 tinct from the enclosing grit. These fragments are very like the 

 underlying slates, and suggest immediately a derivation from them, 

 which seems to be what Murchison means by saying the grits are of 

 regenerative origin. This special slate-conglomerate is not always 

 present at the base, but is found nowhere else within the eastern 

 band of grit with M'hich I am now dealing. The second point to be 

 noted is that these Eastern grits never show any bedding, — a mark 

 of distinction, when the exposure is large enough, between them and 

 any similar grit belonging to No. 5 of the lower group. 



Coming now to the line of junction between the two series, the 

 main feature in its great irregularity. The subdividing lines be- 

 tween the groups of the lower series are not quite straight, but they 

 have a remarkable general parallelism. This will be much impressed 

 on the observer's mind if he fix their limits in each valley indepen- 

 dently, and discover that when these points of division are joined, 

 they form nearly uniform lines. But when we come to the line of 

 junction now under consideration, it is wholly dificrent. This was 

 first seen by me in the patch marked as an outlier to the south of 

 Woolstaston (sec fig. 1). 



