272 C. LAPWOKTH OK THE MOFFAT SEEIES, 



(Hall), Leptograptusflaccidus (Hall), Diplograptus quadrimucronatus. 

 To the left the strata are excessively metamorphosed and are of 

 a deep purple colour ; those to the extreme south-west appear to 

 belong to the Glenkiln group. 



RisJcinhope Burn (fig. 10). — Passing over the very indifferent 

 exposure of the strata of this band in the glen of the "Whitehope 

 Burn, we cross the succeeding ridge into the higher portion of the 

 hollow valley of the Biskinhope. This little stream runs generally 

 along the strike of the dark shales, and affords many small sections 

 in its banks. In the lowest of these sections we have a full exhi- 

 bition of the zones of D. vesiculo&us and M. gregarius, the flag-like 

 strata forming the bounding walls of the stream-bed for some 

 distance, and clearly arranged in a distinct anticline. 



Higher up the stream an ascending section may be traced through 

 all the succeeding Birkhill zones into the grey flags of the R.-maximus 

 band, the strata dipping to the south in their natural order. Some 

 little distance beyond, a similar succession can be made out on the 

 north leg of the anticlinal. The miniature cliffs which next form 

 the south bank of the- stream expose a continuous section of the 

 contorted bands of the Birkhill Shale. Especially conspicuous are the 

 peculiar greenish-yellow beds of the zone of M. spinigerus, with their 

 Annelid -trails and characteristic superficial reticulations. Beyond 

 them the white-lined flaggy shales of the R.-maximus band abound, 

 and are seen to be in irregular contact with the greywackes, which 

 here form a portion of the southern bank. At the head of the 

 gully the grey and black beds again emerge and yield well-pre- 

 served fossils of the R.-maximus band. All the strata described 

 clearly form portions of a single anticlinal, the axis of which crosses 

 the stream at a very oblique angle, about 200 yards above the point 

 where the dark shales are first apparent. 



To the south the greywackes last mentioned are faulted against 

 the following succession : — 



Greenish-grey shivery inudstones (S. at 60°) 5 feet. 



Dyke of zeolitic trap 8 feet. 



Thick -bedded black flags and shales with D. vesicidosus, M. 



gregarius, &o 20 feet. 



This can only be interpreted as the southern side of a second anti- 

 clinal, faulted along the summit of the arch, the dyke of trap coming 

 into the place of the D.-anceps band of the Upper Hartfell Shales. 



A hundred yards beyond the section last noted, and in the line of 

 strike of its component beds, we meet with the missing D.-anceps zone 

 in a small score in the hill-side to the south. It is imbedded in a 

 convoluted mass of slightly altered " Barren Mudstone." The pecu- 

 liar soft black seams of the zone are easily identified and yield (as 

 usual in a state of partial relief) its conspicuous species Dicellograptus 

 anceps (INich.), Diplograptus truncatus (Lapw.). The general ar- 

 rangement of the dark shales in the glen will be understood on an 

 examination of the following section (fig. 10), in which all the 

 foregoing facts are generalized. 





