Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/848

708 and grits were considered to be "Upper Old Red Sandstone," but in reality they in no way differ from the beds of the Glengariff-grit and slate series. This view is confirmed by the examination of the beds for several miles on both banks of the river; and we therefore conclude that the Lower Carboniferous beds rest directly on the Glengariff-grit series, the Old Red Sandstone being altogether absent.

Prof. Jukes and Sir R. Murchison have drawn attention to this section as illustrating the rapid thinning of the Lower Carboniferous slate and Coomhola-grit series as compared with their development at Bantry; this explanation seems to me insufficient.

2. Section between Kenmare and the Suspension Bridge.—In this section hard green grits and purple slates, characteristically representing the "Glengariff-grit series," immediately underlie the Lower Carboniferous beds, so that there is clearly no space for any of the strata representing the Old Red Sandstone. The purple slates belonging to the upper division of the series are well laid open in the river Sheen, above its confluence with the Roughty.

3. Section at Sneem.—The sections in the hills to the east of Sneem are remarkable for their continuity through a vast thickness of strata from the Lower Carboniferous beds downwards. At Knockanamadane and Knocknagullion, a thickness of beds of not less than 8000 feet may be traversed bed by bed, maintaining a steady dip towards the S.S.E. at angles of 60°–70°. The beds belonging to the "Glengariff series" consist principally of purple slates with occasionally beds of green grit, and these are overlain by beds which I consider to be Lower Carboniferous. The first section we visited is that laid open in the bed of the Tahilla river, which falls into Coongar Harbour. Commencing at the chapel by Tahilla Bridge, we find ourselves on dark grey and blue slates which yield fossils of Lower Carboniferous age. Below these come olive-grey and greenish grits, sometimes calcareous; and at a distance of about 500 yards above the bridge we arrive at the junction of the Lower Carboniferous with the "Glengariff-grit series," the Old Red Sandstone being evidently absent. At this junction there is some appearance of unconformity between the two formations, several beds of Carboniferous grit apparently terminating obliquely against the purple slates of the "Glengariff series." I here give a section and plan of this very interesting spot (fig. 3), as it thoroughly satisfied us of the complete absence of Old Red Sandstone, and that we had here representatives of formations separated from each other by the wide interval of a whole geological period.

4. Several other sections in the neighbourhood of Sneem go to confirm the view of the entire absence of the Old Red Sandstone; for on descending the mountains towards the coast, you pass over the highly tilted edges of similar beds of purple slate, several thousand feet in thickness, and then reach the grey grits and olive-coloured shales of the Lower Carboniferous series. The notion, therefore, of a passage upwards from the Glengariff beds into the Carboniferous through the Old Red Sandstone seems to have been founded on a miscon-