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north-west. At Lurganville, 20 miles south-west of this, and a mile 

 and a half south-east of Moira, it dips north-west at from 3° to 5°. 

 Again, from Waringston westward, the grauwacke joins trap as far as 

 Rich Hill, ten miles ; next limestone south of Loughgall, three miles, 

 and then old red sandstone to Armagh, two miles. After that it is 

 in contact with carboniferous limestone, which continues by Middle- 

 ton, Monaghan, and Clones, to join the great limestone district about 

 Lough Erne. I go into these details to show that there may be either 

 of two conditions existing along this line of junction ; the first that 

 there may be a fault along the north-west margin of the grauwacke from 

 Hollywood to Armagh, a distance of above 40 miles. The chief ar- 

 gument in favour of this view is the kind of succession at the surface 

 that occurs in passing westward over the country on the north side 

 of this junction ; there is new red sandstone, trap, mountain lime- 

 stone, old red sandstone. The other view of this case is, that as it 

 stands it may be without a fault. The dips along the junction are all 

 at a low angle to the north-west, away from the grauwacke, the usual 

 way in Ireland along scores of miles of such junctions. In this case the 

 carboniferous sea was deep at Armagh at the time of the deposition of 

 the limestone there, but very much deeper at Hollywood, where, by the 

 usual succession, the limestone must be 2000 feet below the surface, so 

 as to have room over it for the coal-measures, and part of the new red 

 sandstone, which are at sea level there. These upper rocks may have 

 been deposited at a low angle, having their outcrop resting against a 

 steep old sea shore at Comber, and according as they were deposited one 

 covered up the other, and none but the last appeared at the surface ; 

 this last, covering up all the others along this junction, and concealing 

 all the outcrops. 



As I have already stated, this rock appears to be most developed in 

 the vicinity of Belfast. On the southern shore of Belfast Lough some 

 dislocated patches of the magnesian limestone are visible, and even a 

 small area of the top of the coal-measures, which immediately underlie 

 them, appears on both sides of the little pier at Cultra. Prom the west 

 side of the coal-measures at this place, in the new red sandstone, the 

 beds have a low dip westwards, which continues as far as rock is vi- 

 sible at low water towards Belfast. The coarse conglomerate which is 

 usually found to exist at its base is not to be seen at the base of the 

 red rocks here joining the coal series ; but the locality is much dis- 

 located, and penetrated by whin dykes, and there is probably a fault 

 on the west side of the coal-measures, in which the conglomerate is 

 buried. 



The whole formation in other countries is composed of conglome- 

 rate in the lower part, red sandstone in the middle, and soft red marls 

 in the upper part. In this locality, though we cannot see the lower, 

 the middle and the upper parts are well developed, and agree with the 

 description above. 



E. I. a. peoc. — vol. x. 2 IT 



