Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/567

Rh Nodular limestone bands have been referred to as making their appearance in the highly cleaved and contorted green shales. Near the top of these shales the limestone bands become more predominant, and the nodules gradually change into continuous layers succeeded by thicker strata, the whole forming a finely developed mass of Coniston Limestone, in some parts very fossiliferous. The higher beds of the series, however, again assume a nodular form; and at the top of the group a very singular deposit is seen. This bears some resemblance to the nodular ash-breccias; the nodules, however, prevail to a much greater extent.

This bed is so conglomeratic in its aspect as to appear, at first sight, a mass of this nature overlapping the Coniston Limestone. This, however, is clearly not the case, as there occurs underneath this curious nodular bed a mass of a somewhat similar kind, the two being separated from each other by apparently ashy shales in which nodules of limestone are seen.

This singular nodular mass is probably near the horizon of the band of limestone which occurs at Shap Wells as a calcareous breccia.

Dark-coloured rocks are seen resting conformably on the nodular limestone. In their nature these rocks have a great affinity to the Graptolitic Mudstones of the Lake-district. They occur in cliffs which are very inaccessible, and therefore could not be well searched for fossils. Judging from their mineral aspect (and this is a well- marked feature in the Graptolitic Mudstones), we are disposed to refer them to this position.

The rocks south of the Coniston Limestone of Portraine form a synclinal trough. Here the strata are more accessible than where the black shales occur. They consist of fine-grained greenish-coloured shales, having dark grey rocks intercalated with them. The former, as regards their nature, are identical with the green rocks of the Knock beds. Their position also allies them with the latter strata; and they are succeeded by hard grey rocks having a close resemblance to the Coniston Flags. Taking the Portraine section collectively, the nature, the arrangement, and the fossils contained in the rocks here are such as to justify us in referring them to positions lying between the Borrowdale group and the Coniston Flags of the north of England.

To the south of the synclinal alluded to, the continuity of the Portraine section is broken, the coast being for a short distance sandy.

Beyond this sandy area the Bala rocks again appear in the form of ashes and traps, the latter being the most abundant.

The line of strike before alluded to, if continued south-west from Portraine, would bring us to another area where the Coniston Limestone and its associated rocks are seen. This area is in the co. Kildare, about three miles north of the town of Kildare; and here