C. LAPWORTH ON THE MOEFAT SERIES. 283 



the lowest division of the Moffat Series, but the determination of 

 its relation to the so-called " axial " or " Ardwell " beds, which 

 bound it on the south, has a most important bearing upon the 

 general Silurian geology of the south of Scotland. 



At Shorthope, which may be regarded as marking the easterly 

 commencement of the band, only Birkhill Shales are visible. These 

 are thrown into several parallel undulations. As usual, the most 

 conspicuous beds are the flag-like shales of the D.-vesiculosus and 

 M.-gregarius bands of the lower group. They are greatly indurated, 

 and yield only occasional examples of Diplograptus vesiculosus (Nich.), 

 Climacograptus rectangularis (M'Coy), Monograptus tenuis (Portl.), 

 &c. The grey and black shales of the upper group have undergone 

 even a larger amount of disturbance, but are easily recognized by 

 their peculiar mineralogical characters and their relation to the 

 surrounding greywackes. 



At Brockhope the band widens greatly, and exposes the under- 

 lying Hartfell Shales, the " Barren Mudstone " occupying its natural 

 position in the centre of the band. 



Some of the deeper beds of the Hartfell Shales are visible at 

 Phawhope, where for the first time we are presented with an 

 exposure showing the Grey group passing below the greywackes to 

 the north. To the south the same beds, with their characteristic 

 white-clay bands and peculiar fossils, Monograptus Halli (Barr.), 

 M. spinigerus (Kich.), lie distinctly between the greywackes and 

 the black division of the Birkhill series in several localities. 



Beyond Phawhope the band crosses the watershed into the head 

 of Selcoth Burn, and forms one of the three bands of Craigmichan 

 Scaurs, where its characters and relationships have been already 

 described. 



Everywhere along this extended line the axis of the anticlinal is 

 so greatly inverted that the Upper Birkhill Shales seem to repose at 

 a very small angle upon the greywackes to the south. 



Two other anticlinals of Craigmichan are also partially visible in 

 the Ettrick valley. The central arch crosses the river above Phaw- 

 hope, but soon disappears. 



ii. Entertrona. — The southern arch is best exhibited in the small 

 burn called Entertrona, where beds of the Glenkiln division are 

 abruptly collocated with the greywackes to the north, and yield 

 Leptograptus, sp., Bidymograptus superstes (Lapw.), Dicellograptus 

 divaricatus (Hall), Climacograptus ccslatus (Lapw.), Diplograptus (?) 

 bimucronatus (Nich.), Ccenograptus gracilis. They are faulted against 

 the upper or grey group of the Birkhill Shales, which show the black, 

 white, and grey lines with which we are already so familiar. The 

 fossils present include, among others, Rastrites maccimus (Carr.), 

 Rastrites hybridus (Lapw.) Retiolites perlatus (Nich.), Monograptus 

 runcinatus (Lapw.). These fossiliferous strata dip steadily to the 

 southward at a small angle, passing upwards into the barren flag- 

 stones and greywackes of Ettrick Pen. 



iii. Belcraig Burn (PL XIII. Plan H). — Several exposures of the 

 dark shales of this band occur in the heights to the south-west of 



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