82 EIGHTH REPORT — 1838. 



In this valley the strata of the carboniferous limestone form a syn- 

 clinal depression, the beds to the north of the river dipping south, and 

 those lying south of it dipping to the north. 



On the south side of the Suir, the strata which have already been 

 described are observed resting in the same order of succession on the 

 extensive clay-slate district of the county of VVaterford, in which are 

 situated the important slate quarries of Glenpatrick and other localities. 



Proceeding to the southward from the clay-slate district of Water- 

 ford, the line of section crosses the summit of the MonavuUagh moun- 

 tains, which consist of a vast accumulation of conglomerate similar to 

 that already described, and forming an escarpment nearly perpen- 

 dicular for an elevation of about 500 feet ; the strata dip to the south 

 at an angle of 10° from the horizon. As in the cases mentioned be- 

 fore, this conglomerate is succeeded by coarse red slate and quartz 

 rock, but in descending towards the river Blackwater, near to Lismore, 

 we find beds of roofing slate interstratified with the quartz rock, and it 

 is to be observed generally, that the roofing slate occurs only in the 

 upper portion of the red slate series. 



Approaching the Blackwater, the clay slate is succeeded in a con- 

 formable position by yellowish white sandstone and sandstone slate, 

 which in many localities is found to contain casts of Calamites, and 

 appai-ently of some varieties of Stigmaria, and these again, as in the 

 valley of the river Suir, by the greenish gray imperfect clay slate, 

 which alternates with the limestone of the valley of the river Black- 

 water. This valley, like that of the Suir, is connected with the ad- 

 mitted carboniferous limestone district of the counties of Cork, Tippe- 

 rary, &c. 



The whole of the limestone beds of the river Blackwater at Lismore, 

 dip to the south, but not at equal angles from the horizon ; on the 

 north side of the valley the angle of incUnation does not exceed 20°, 

 while in the middle and southern side it amounts to 80° or 85°, but 

 still the inclination is to the south. 



Proceeding to the southward beyond the limestone boundary, we 

 find greenish gray clay slate and yellowish sandstone similar to those 

 already described on the north side, inclining to the south at an angle 

 of about 85° from the horizon. Judging from the position of the strata 

 alone, these schistose and arenaceous beds might be supposed to be 

 superior, instead of inferior to the limestone. But arguing from the 

 analogy afforded by other localities in the south of Ireland, there can 

 be no hesitation in admitting that the strata are here contorted. 



Contortions are frequently observable on the sea coast and in many 

 precipices and quarries in the interior of the country, and although, 

 when seen at the surface, the strata everywhere dip towards the south, 

 still these strata present a series of convolutions, frequently on a small 

 scale, both sides of which incline to the southward, though usually at 

 different angles. This peculiarity is general throughout the southern 

 counties, and is alike observable in the transition slate, the limestone 

 series and the culmiferous strata, — a circumstance which shows the 

 necessity of extreme caution in making calculations as to the probable 



