8 Mr, Weaver on the Geological Relations of the South of Ireland. 



being- of more casual distribution^ for example^, the sandstone conglomerate in 

 Dunloe Pass west of the lower lake of Killarney. Greenstone*^ and hornstone 

 porphyry, are more local occurrences : the former may be observed in Begnish 

 Isle adjacent to Valentia Island, and the latter within the range of Mac-Gilli- 

 cuddy's Reeks. In the general series of these rocks, the purer clay-slate, fit for 

 roofing, occurs in beds incidentally distributed and of variable thickness, yet 

 bearing but a small proportion to the entire mass, e. g. the indifferent, bluish 

 and greenish slates procured from Mangerton and Glen Flesk, and the reddish 

 brown from Dunloe Pass ; but in the island of Valentia an excellent roofing- 

 slate is obtained, which may vie with any for firmness and durability, possessing 

 also an agreeable subdued purplish colour. Beds of quartz-rock, hornstone, 

 and lydian-stone, also occur incidentally in the general, compound series ; but 

 the last-named substance is comparatively very rare in the grey wacke and slate 

 country, its more usual representative being there a flinty slate. 



(10.) The common character of the clay-slate conglomerate and grey wacke is that of a base 

 of slate or quartzy slate, enveloping rounded and angular fragments of quartz and slate (some- 

 times in the form of considerable pebbles) but very rarely inclosing small portions of felspar also. 

 The greywacke slate is the same rock, of finer grain and fissile structure. Numerous scales of 

 silvery mica enter also more or less largely into the composition of these rocks, as wellas occa- 

 sionally into that of the purer clay-slates. 



A great variety of these substances, together with some sandstone conglo- 

 merate, may be observed on the coast adjacent to Smervvlck harbour, beds 

 of clay-slate also appearing in the association. The beds in this quarter dip 

 65° to 80° S. ; but in traversing the peninsula southward, to the confines of 

 Dingle bay, they gradually acquire a vertical position, then a northerly in- 

 clination, and re-assuming a vertical position, they again acquire the southerly 

 dip. In the Cahir-conree chain a disposition somewhat similar may be observed: 

 thus in the northern face of the eastern quarter, where the Slieve-Meesh 

 range may be said to commence and in which old red sandstone prevails, strata 

 of sandstone appear, including some of conglomerate dipping 50° to 45° to the 

 north ; but on penetrating into the mountains on the south by the valley which 

 runs about two miles and a half in that direction, its mouth frontin"- Kilg-obbin, 

 these sandstone strata may be observed gradually merging into varieties of 

 greywacke and greywacke slate, associated with red, brown and greenish co- 

 loured clay-slate, and with occasional beds of similarly coloured sandstone ; 



* Namely, true greenstone, a compact, or subcrystalline compound of felspar and hornblende. 

 In Kerry, and generally in the South of Ireland, the rock popularly called greenstone is a grey- 

 wacke, or sandstone, of a greenish hue, and the brownstone of the country consists of the same kind 

 of rock of a brownish or reddish colour. 



«# 



