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



were fixed in the level ; but from thenceforward, namely, to May 1829, the average discharge from 

 the mine was 8 or 9 tons per minute. When required, the steam engine (of 36-inches cylinder, 

 working single,) has been made to throw out 13^ tons of water per minute, or nearly 20,000 tons 

 in 24 hours. 



(46.) In Crow Island, which is situated about half a mile to the eastward of Ross Island, 

 and is of small extent, being only about twenty fathoms in breadth, the mine is said to have 

 yielded about 100 tons of copper ore of inferior quality. This was obtained from slight, contem- 

 poraneous strings, isolated portions and particles of ore, of uncertain distribution in the blue lime- 

 stone rock, and blended more or less with calcareous spar, and partially contaminated by an inter- 

 mixture of blende, iron pyrites, and galena ; the formation being analogous to that prevailing in 

 the vicinage of the Blue Hole at Ross Island, was poor and unpromising. The principal working 

 was about fifteen fathoms long and six fathoms deep, the line of excavation ranging 30° west of 

 north and east of south, with an inclination of 65° to the south of west. 



II. — Carboniferous Series. 



I. In South Munster, viz., in Cork, Limerick, and Kerry. 



Old Red Sandstone*. 



(47.) In the eastern quarter of our fields I have first to notice the old red 

 sandstone of Kilvvorth mountain and the adjacent hills, on the north of the 



* I may here remark, that tracts of transition rocks analogous to those described in this paper, 

 (in which conglomerates, sandstone, and quartz-rock, are of such common occurrence,) appear in 

 many cases to have yielded a large proportion of the materials of which the old red sandstone of 

 British geologists is composed. And that the great carboniferous order, or series, forms, in gene- 

 ral, an independent and consistent group, appears proved, — 1. by the predominant unconformity 

 of its position, in relation both to subjacent and superjacent systems ; 2. by the general absence 

 of organic remains in the old red sandstone ; 3. by the organic reliquiae peculiar to the carbo- 

 niferous limestone and the coal formation ; and 4. by the not unfrequent interstratification of 

 these three members in the order of succession. Several organic exuviae, however, being common 

 both to the transition and carboniferous orders, while many are peculiar to either series, affinity 

 as well as difference is thus indicated ; but the discordant position of the two systems appears 

 conclusive as to their different eras of production. 



Some of the foregoing positions I find entertained also by M. Hoffmann in his General View of 

 the Geological Relations of the North West of Germany, 1830. (vid. Uebersicht 2te Ahtheilung, 

 pp. 503,504, and 589; — positions which I advanced and partly developed between the years 

 1818 and 1824 in the Geological Transactions and Annals of Philosophi/. See in particular the 

 Annals of Philosophy for the years 1821, 1822, 1823, and 1824. But I differ from that author 

 in not including, as he does, in the carboniferous series, the red sandstone that is interposed be- 

 tween the coal measures and the magnesian limestone (Zechstein). In this, however, he is not 

 singular, as German geologists in general had, to that date, done the same, comprehending with 

 him under the head of rothc-todte-liegende the whole of the carboniferous series, together with the 

 red sandstone subjacent to the magnesian limestone. If the use of the term rothe-todte-liegende 

 be still continued, it may be well to restrict it to this red sandstone, lying between the coal forma- 



