Fearnsiues, Elles, Smith — Palceozoic Rocks of Pomeroy. 109 



characterized by the presence of M. Sedgwickii var. distans and by 

 numerous Petalograpti. The thin temiis-li]xQ Monograptus discretus 

 is also seen, but is not so abundant at Mullaghnabuoyah as at the Lime 

 Hill exposure. At Lime Hill, the lowest bed exposed is again a blue- 

 black mudstone, but is only faintly banded. A foot or two higher 

 this gives place to a somewhat calcareous dark-coloured rock, which 

 contains well-preserved examples of the various Petalograpti, with 

 what appear to be fragments of Lamellibranchs. These, with inter- 

 bedded softer black mudstones, continue for some six feet ; but their 

 higher bands contain no obvious Petalograpti, and, becoming suddenly 

 paler upward, pass into rocks similar in texture to the harder beds 

 discussed, but of variegated green and yellow colours. A break in the 

 section possibly cuts out a foot or two of rock ; the next rock seen has 

 regained its intense black colour, and appears as a black micaceous 

 mudstone with sooty black shale partings. These highest somewhat 

 micaceous beds appear to be the Graptolithus Sedgivichii horizon 

 of Portlock, and their calcareous beds also yielded him certain Lamelli- 

 branchs. They also contain well-preserved examples of M. involutiis, 

 M. discretus, and many obscure fragments of Orthis and other Brachio- 

 pods. The total thickness exposed at Lime Hill is something less 

 than 20 feet ; and owing to the superabundance of drift, no passage to 

 the next higher Corrycroar or Tarannon group can be seen. The 

 occurrence of the pale green and yellow bands among these Sedgwickii 

 beds is exactly paralleled by the similar occurrence at the same 

 horizon at Dobbs Linn and Lockerbie, in the Moffat district of South 

 Scotland, and by the variation in colour shown by the Sedgwickii 

 beds of Skelgill. 



• 



The Corrycroar Group. 



Of this, the highest Silurian series exposed within the Pomeroy 

 area, little could be ascertained during the time at our disposal. 

 The only exposure we could find is in the gorge of the Corrycroar 

 stream, where, along the river bed, beautifully even-bedded flags of the 

 Gala type are laid bare for nearly half a mile. Unfortunately, not- 

 withstanding their beautiful lamination, it proved impossible to 

 obtain fossils from these beds ; and, as a result of two days' work, only 

 two fragmentary Graptolites with cells of the type of M. vomerinus 

 were discovered. The rocks are green, flaggy, and very monotonous ; 

 they are hard, somewhat brittle, and very well jointed, and, indeed, 

 are very like the fine-grained members of the Gala grit series of South 

 Scotland, but, in the 100 or 150 feet exposed, include no beds coarse 



