268 



C. LAPWORTH ON THE MOFFAT SERIES. 



They form two subsidiary and partly broken anticlinals, and the 

 highest beds pass visibly beneath the greywackes to the north. 

 Strata belonging to the D.-cometa, M.-spinigerus, and R.-maocimus 

 zones are exposed here and there, and fossils are abundant and well 

 preserved. The white lines of the highest division are very con- 

 spicuous, as are also the inferior bands of grey sandy mudstone and 

 shivery shale, with their characteristic Annelide-trails and concre- 

 tions. The commonest fossils are Rastrites maximus (Carr.), R. 

 capillaris (Carr.), Diplograpsus ptalmeus (Barr.), Monograptus Halli 

 (Barr.). 



Black Grain. — Proceeding to the south-westward, the band next 

 crosses the watershed into the basin of the Ettrick, where its rocks 

 are first visible in a small score near the head of Black Grain. Here, 

 although the beds are highly metamorphosed and wholly unfossili- 

 ferous, their steady dip and the distinctness of the mineral characters 

 of the various zones, enable us to recognize the chief subdivisions at 

 a glance. The Barren Mudstones of the Hartfell series occupy the 

 centre of the exposure. To the south they are covered by the black 

 flags and shales of the Lower Birkhill ; and the exposure is closed 

 by the more recent grey and black shales with white-clay bands, 

 which dip steadily under the greywackes to the south at an angle of 

 about forty degrees. 



7. — Generalized Section across Fala Grain. 



D. 



Cb. 



Ca. 



B. 



Greywackes and 



Grey flaggy shales with black and 

 white seams. 



Hard black flags and shales, with 

 seams of variegated mudstone. 

 Dvplograptus vesiculosus, Mono- 

 graptus gregarius. 



Pale non-fossiliferous mudstones. 



Fala Grain (fig. 7). — This reading of the sequence is confirmed by 

 the beautiful section visible in Pala Grain, a small burn descending 

 the southern slope of Herman Law. In the lower portion of its 

 course the bed of this stream coincides with the general direction of 

 the black- shale band under description, and the Moffat strata are 

 admirably exposed in the steep cliffs on its banks. The first beds 

 visible to the north-east are grey and black shales with a northerly 

 dip. These are underlain by the main mass of the zones of M. gre- 

 qarius and D. vesiculosus, whose variegated and hard flag-like strata 

 form the walls of the gorge for a distance of nearly 200 yards. 

 A great thickness of barren grey mudstone succeeds, and probably 

 forms the lowest stratum exposed. To the south the dark shales and 

 flags reappear, and, as before, in an almost vertical attitude. Near 

 the foot of the stream the section is completed by the grey and 

 black shale group with the usual white-clay bands, in conformable 

 contact with the greywackes to the south, conspicuously displayed 

 in the hill-face to the left. 



