Mr. Weaver on the Geological Relations of the South of Ireland. 7 



troughs ; the ridges containing a central axis of vertical bedsj from which the 

 lateral strata diminish in elevation on each side, while in the troughs are in- 

 closed other beds which gradually approach to the vertical position in the 

 centre of the trough. These variations in the line of range and dip occupy 

 spaces of greater or less extent; but independently of this general disposition, 

 involutions and contortions of the strata are also occasionally observable. 



(8.) Though the rocks of this portion of Ireland present great differences 

 in aspect and structure, the principal masses may, in a great measure, be re- 

 ferred to compounds of quartz and slate variously intermingled and associated. 

 Limestone, another principal mass, also otfers considerable varieties, and 

 upon its confines with other rocks, it is found more or less charged with a 

 portion of their ingredients. In generalizing the view, the country may be 

 considered as chiefly composed of greywacke, slate, and limestone. 



To be more particular, we may designate the whole series as consisting of 

 simple and compound rocks. The simple rocks are clay-slate, quartz-rock, 

 hornstone, lydian-stone, and limestone. 



The clay-slate is bluish, greenish, seldomer blackish grey, often brownish, reddish or purplish, 

 and glimmering, or glistening, more rarely wholly dull. In some quarters the slate appears as a 

 quartzy clay-slate, and in others as a shivery shale. 



Quartz-rock, generally of various sliades of greyish white, more or less compact and fine splin- 

 tery, or granular ; sometimes also reddish, bluish, or greenish, when coloured by an intimate mix- 

 ture of the substance o'f clay-slate. 



Hornstone, or chert, yellowish, reddish, or greyish white, compact, even, and fine splintery. 



Lydian-stone of its usual aspect, but sometimes passing into flinty slate. 



Limestone of various shades, from dark to light bluish grey, also pale grey with streaks of 

 reddish and yellowish white, more rarely black ; and in structure varying from compact to sub- 

 lamellar. 



The limestone in some quarters forms frequent alternations with the lydian-stone, hornstone, and 

 quartz-rock, involving in its substance also shapeless portions of those rocks, for example — in 

 several of the beautiful isles of the Lower Lake at Killarney, in some of which, as in Ross Island, 

 beds of clay-slate are likewise interposed in the series; and in Muckrnss peninsula, both on its 

 northern and southern shores, the limestone may be observed alternating with slate and grey- 

 wacke slate, where it borders upon rocks of that description. In other quarters the limestone is 

 less interrupted, appearing in purer beds which afford excellent lime, e. g. in the Drishane 

 quarries near Millstreet, or being deteriorated by a commixture of siliceous particles become less 

 tractable, e.g. in the limestone of the Kenmare district. 



(9.) The compound rocks may be enumerated under the following heads : 

 clay-slate conglomerate, quartz conglomerate, greywacke, and greywacke slate, 

 sandstone conglomerate, sandstone, and sandstone slate, greenstone, and horn- 

 stone porphyry. Of these the greywacke, greywacke slate, sandstone, and 

 sandstone slate compose the predominant rocks, the coarse conglomerates 



