488 G. H. Kinahan — }Yater Basin of Lough Derg. 



the west, eastward into the limestone country bordering Lough Derg, 

 but the associated faults could only be proved to have shifted the 

 beds in parts of them. The series of faults seen in this district are 

 made much clearer by the presence of such different kinds of rocks 

 now in juxtaposition, although they were originally several hundred 

 feet asunder ; the dark blue limestones and the yellow and red 

 " Old Eed " rocks occurring on one side of the fault, while the 

 grey and green Silurian rocks are found on the other. In places, 

 some of what are here considered faults might possibly be only 

 Silurian cliffs, at the base of which the Old Eed Sandstones and 

 Limestones were deposited, as the rocks seem to strike with the line 

 of fault ; this is more especially the case with the Cloonnagro and 

 Corra fault. But that they are really lines of dislocation seems 

 most probable, as there are so many of them in nearly parallel 

 lines ; also the basal beds of the " Old Eed " on the upthrow and 

 downthrow sides are similar, which would scarcely be the case if 

 they were lines of cliffs. 



Bounding the south of Slieve Aughta is the Scarriff valley, which 

 has its accompanying fault on the north of the valley, running from 

 Feakle Lower to Mount Shannon, the Carboniferous Limestone and 

 the Silurian rocks being brought together a little east of the hamlet 

 called Coolcoosaun. This fault was observed a mile and a half S.E. 

 of Feakle, and from that it was traced by Coolcoosaun toward the 

 east ; it appears to extend into Lough Derg, but no positive proofs 

 of its existence were found farther than the Bow Eiver. 



A second valley runs from Lough Blarnagh into the catchment 

 basin of Lough Graney at Lough Ea, and from Lough Ea down the 

 Cahir Eiver to Lough Graney ; while from Lough Graney it extends 

 eastward along the Corra and Derrygoolin rivers to the flat country 

 near Lough Derg ; leaving the Lough Graney catchment basin on 

 the north of Ardeven. The accompanying fault can be traced from 

 near Maghera Lough to Ardeven, being very conspicuous in the 

 Corra Eiver, and near the village of Cloonnagro. 



A third valley extends along the Hollymount Eiver to Lough 

 Nagilkagh, on the east of which it crosses the watershed of the 

 catchment basin of Lough Graney, and proceeds down the Druman- 

 doora Eiver to Lough Graney. East of the last-mentioned lake, it is 

 occupied by the Bleach and Woodford Elvers. The accompanying 

 fault lies a little to the north, and has been proved from Carheeny 

 Lough to Corlea Bridge, and from Woodford to Lough Derg ; but 

 between Corlea and Woodford it was not ascertained, as the country 

 is covered with deep drift and bog. At Corlea the Carboniferous 

 Limestone is brought down against the Silurian rocks ; near Wood- 

 ford, the limestones and sandstones are thrown against one another ; 

 while on the shore of Lough Derg the unstratified portion of the 

 Lower Limestone is brought down against the stratified part. From 

 Corlea to Carheeny the fault is well marked, and divided into two 

 branches on the west of the village of Lannaght. A branch also 

 appears to run eastward from Lough Atorick; this, however, could 

 not be proved. 



