C. LA.PWOETH ON TfiE MOFFAT SERIES. 257 



edge of the Long Cliff, down the base of the D.-anceps zone into the 

 Long Burn, at a point near its lower termination. The contorted 

 M.-gregarius beds which bound it on the east form the whole of the 

 Long Cliff, below the fault, from end to end, for a distance of about 

 300 yards. Towards the north the contortion gradually decreases 

 in intensity till near the upper extremity of the gorge, where we 

 have a complete confirmation of our reading of the cliff- structure. 

 Here the M.-gregarius zone we have traced upwards shows all its com- 

 ponent strata dipping in regular (but inverted) order, and yielding- 

 its peculiar fossils in a finer state of preservation than anywhere 

 else within the limits of the glen. It passes down gradually, bed 

 upon bed, into the conspicuous D.-vesiculosus zone, the thick flaggy 

 strata of which form the steep walls of the head of the gorge, and 

 expose beyond them traces of the shivery D.-acuminatus zone, and 

 of some pale-green strata that may belong to the Barren Mudstone. 



To complete our section we have finally to ascertain what are the 

 beds that lie between the contorted M.-gregarius zone of the Long 

 Cliff and the grits and flagstones that are visible occasionally along 

 the upper edges of the East Cliff, forming the boundary of the Moffat 

 Series in that direction. Unfortunately immediately in our line of 

 section the required beds are almost wholly obscured by turf and 

 talus. At one spot, however, near the centre of the Long Burn, 

 where it commences its north-westerly curve, several of the beds of 

 which we are in quest are shown in a fine cliff-section. They are 

 seen to consist of thin bands of grey shales and mudstones, with 

 here and there a thin black line. Among them occur several seams 

 of pure white clay, weathering into small flaky fragments, which 

 are scattered over the whole section, and give it a most peculiar ap- 

 pearance when viewed at a little distance. It is impossible to doubt 

 for a moment that we have before us the first Grey-shale group, or 

 Upper Birkhill Shales of the waterfall, which, however, instead of 

 reposing upon the greywackes, actually pass beneath them at a low 

 angle. The few fossils procurable, which include Monograptus 

 spinigerus (Nich.), M. Hisingeri, and Diplograptus Hughesi, distinctly 

 confirm this conclusion, as also does the fact of the presence of 

 the hard grey band forming the base of the group, which is seen 

 running from side to side of the bed of the little stream immediately 

 below. A little further to the north, and in the contorted beds 

 above, several additional Upper Birkhill Graptolites are obtainable. 



Beds belonging to the same set of grey and black shales crop out 

 at intervals along the whole remaining length of the East Cliff below 

 the greywackes, between the latter and the contorted zone of M. 

 gregarius ; and their precise identity with those of the grey group of 

 the corrie is placed wholly beyond doubt when the several exposures 

 are examined in detail, the sequence of the various bands agreeing 

 with those of the latter in every respect. 



The study of this section of the North Cliff has taught us that in 

 the upper portion of the glen there are no black shales present that 

 do not belong to the Moffat Series, as exposed and tabulated in our 

 typical section of the Main Cliff; and, furthor, that as the zones in 



