172 



THE GEOLOGIST. 



found Orthis and Euomphahis at Coorsan, but not Syringopora. I conclude, 

 therefore, though not hastily,' that these boulders may have belonged to some 

 other exposed rock of Mountain-limestone further north. 



Mountain Limestone. Coorson point (Lough B,ee). Strike west and south, dip 

 east. Crops out at the surface. Angle about 40 or 43 degrees. 



I have so named the "Productus" and " Spirifer" limestones on account of the 

 abundance of the fossil mollusca of these two forms. The quarry at Coorsan 

 Point, on the borders of Lough Ree, have yielded me about ten species, besides 

 Terebratula and Euomphahis. Here the young geologist may work with pleasure 

 and never tire ; and as he works hundreds of curious questions will arise and ask 

 for solution. I stand on the summits of the quarry, with my back towards the lake 

 and see before me the huge rock in which the encrinite is barely a predominating 

 feature, but where thousands of Mollusca lie entombed. In some places there 

 is a beautiful deposit of calcareous spar, fringed with metallic sulphide, marking 

 the spot where there was a sudden extinction of life. There can be no mistake, 

 for the molluscs are more numerous here than elsewhere.* How is this ? 

 Yonder on the opposite side of the same lake, with a dip eastward, and a strike 

 north and south — the same dip and strike remember, of the stratum before 

 me — thousands of Encrmites lie buried with but comparatively few Molluscs. 

 How can we account for this difference ? Ear away, at Pallykeyron, with nearly 

 the same strike and dip, another stone presents itself to the gaze of the geologist, 

 black, bituminous, aud shaly, almost destitute of fossils; and, according to the 

 lime-burners destitute of lime. These three quarries show at least three states 

 of the Mountain-limestone seas; how they were inhabited; and how their 

 inhabitants lived and died. It would be useless to speculate on the probable 

 thickness of eaeh bed. Reckoned by years how many must have intervened 

 between the first and last deposit of animal-matter in those palaeozoic seas ! 



In this quarry this fringing of metallic sulphate is very common. " It affords an inter' 



esting proof th 

 docomposi 

 An earthei 

 ondistorbc 

 Some luck 

 came to l u 



seen floating on the top, and the hones 

 was found that over the decaying hod 

 separated and precipitated in a dark-col 

 sulphur, of copperas in its green and en 

 mal and mineral matters had mutually' 

 deprived of its oxygen in the process, 1 



1 matter in a state of putrefaction proves a powerful agent in the 

 d substances held in solution, and on then consequent precipitation, 

 ■aining several quarts of sulphate of iron, had been suffered to remain 

 mined in a corner of Mr. Pepy's laboratory for about a twelvemonth. 

 I meanwhile fallen into it and been drowned ; and when it at lenth 

 l oily scum and a yellow sulphurous powder, mixed with hairs, were 

 and the bones of the mice discovered lying at the bottom ; and it 

 ie decaying bodies the mineral components of the fluid had been 

 cd in a dark-coloured sediment, consisting of (/rains of pyrites and of 

 "line form, and of black oxide of iron. The ani- 

 l! upon one another ; and the metallic sulphate, 

 thus cast down its ingredients." — Hugh Miller's 

 old Red Sandstone," 7th ed., p. 217. Was it a solution of sulphate of iron caused the 

 sudden death of the molluscs in tae Mountain Limestone seas ? 



