396 PROF. J. F. BLAKE ON THE MONIAN AND 



near Asterton we walk round an amphitheatre, crossing all the 

 while the strike of anj'-thing that has a strike, and always with the 

 slaty series below and the conglomerate occupying the crest of the 

 hill. The moaning of this still seems pretty plain. Prom hence to 

 the south all that is seen of the upper beds is a long tongue of con- 

 glomerate, with minor beds of grit, which except at one point per- 

 sistently keeps to the top of the hill. At the one point, however, 

 where it descends to the level of the road, there is the greatest diffi- 

 culty that anywhere may be felt about the unconformity. There is 

 here a great quarry opposite Mindtown Farm, and in this there are 

 vertical beds of slate with the usual strike, showing beautifully 

 ripple-marked surfaces, but far more solid than anywhere else. In 

 the higher portion of the same quarry is seen the conglomerate ; in 

 one part it is evidently disturbed, but in the least disturbed por- 

 tion the two rocks have a great appearance of conformity, the con- 

 glomerate being to the east of and therefore below the slate. Still 

 further up the slope of the hill slate is seen again, and finally the 

 continuous mass of conglomerate. This appearance of conformity 

 is very staggering, but we know how easily such an appearance is 

 produced when rocks have been squeezed together, and this, I think, 

 is the only interpretation available in face of the facts already 

 adduced. It is the more easy to accept, because the conglomerate is 

 not usually the base of the series, it is nowhere else followed by 

 purple slate, and disturbance and squeezing have evidently taken 

 place. The purple slate here is much more like the upper mass of 

 that rock to be presently described, and it continues to have this 

 resemblance for some distance to the south, so that I am by no 

 means sure that it does not belong there. Yet in the same direction 

 the rocks become gradually more like the series 'No. 5, till at the turn 

 of the hill by Hill Cottage there is no mistaking them. It is, however, 

 quite possible that the map may be here tinted wrong, especially 

 as the band of hard greywackes jN'o. 4 cannot here be recognized. 

 AVhichever way it is, it will scarceh' affect. I think, the main con- 

 clusion as to the unconformity of the conglomerate. 



On the other side of the tongue matters seem clearer. Along the 

 crest of the hill the hard greywackes are well seen in numerous 

 crags, till they are cut out by the crossing of the conglomerate, and 

 from thence the neighbours of the latter are the purple slates of 

 No. 3, well cleaved, in thin masses and very characteristic. Finally 

 along the southern margin we find the same phenomenon (see fig. 3) 

 as is so conclusive further north. Taking the low path, the innu- 

 merable exposures manifest an apparently continuous sequence with 

 constant strike of purple and pale slates, with occasional grcywacke 

 bands, without a sign of conglomerate ; but mounting the hill the 

 conglomerate is seen again, and the line that must be drawn to 

 separate its exposures from those of the slates is approximately 

 horizontal and entirely transverse to the strike of the latter *. 



* It may be noted that the conglonicrate seen does not resemble the Llan- 

 dovery conglomerate of the neighbourhood, which has a special character of 

 its own. 



