289 



For, taking the slope of the surface from Divis to Lough Neagh, Divis 

 is 1567 feet high; Lough Neagh is 48 feet above sea level; the distance 

 between them on the Divis and Slieve Gallion section is 1 1 miles, 7 

 furlongs; and these data turn out 128 feet fall in a mile; this is 

 supposing that the thickness of the trap at the shore of Lough Neagh is 

 the same as at the top of Divis, namely, 900 feet. This gives an angle 

 of about one degree and one-third. This most probably is about the 

 average dip on the east side of the great basin, of which Lough Neagh 

 and the Bann are in the bottom. From the Deny outcrop eastward 

 the average dip is about the same. 



The second of the circumstances alluded to lies in the line of 

 country between the stations No. 20, at Lurrig, and ]STo.. 26, at Ben 

 Croaghan, in the Table, along the southern border of the mica slate. 

 These stations are upon some of the most elevated positions occupied by 

 the chalk in Antrim, as maybe seen by reference to the Table; and from 

 the outcrop, or aline passing through those stations, it will be seen that 

 the chalk lies upon a bed sloping to the south-west. 



At Lurrig, on the east, No. 20, the chalk stands at 940 feet high ; 

 at Cloghglass Glen, No. 22, at 730 ; thus giving a fall of 210 feet in 

 a south-west direction, in two miles, or 105 feet in a mile. 



At Ben Croaghan, No. 26, on the west, the position of the chalk is 

 1 254 feet high. At Corkey, No. 28, it is 400 feet ; here is a fall of 854 

 feet, in a direction 15° west of south, in five and a half miles, or 155 

 feet in a mile. Both these cases show that the bottom plane of the 

 chalk has a south-west average dip of about one degree and a half, ad- 

 joining the mica slate, and corroborate the view that the chalk forma- 

 tion in the north-east of Antrim dips towards Lough Neagh in basin 

 shape, as it does in other places. 



I have shown in the Table, No. 2, the height of the chalk at seve- 

 ral stations on its outcrop, both in Antrim and Deny. From this out- 

 crop it dips inwards towards the Bann in both counties ; but, besides 

 this, there is a general dip of the outcrop in itself on both sides to the 

 north, putting the chalk zone into the form of a trough or scoop, high 

 on the south at Divis and Slieve Gallion, and low on the north coast. 

 Yet on the north coast it does not dive into the ocean. There are un- 

 dulations and faults in it along the shore, the anticlinals of which affect 

 a north and south direction ; but, as a whole, upon that coast the ge- 

 neral dip is south, at a low angle, all the way from Magilligan,' in 

 Derry, by Portrush, Ballintoy, and Ballycastle, to Murlogh Bay, and 

 showing that it dips inwards in an irregular basin shape towards Lough 

 Neagh, on at least three sides of the great basaltic area. 



Though the chalk assumes a basin shape, as just shown, in the ba- 

 saltic area, as a whole, yet there are irregularities in it, especially 

 towards the margin, in which it deviates from this form. These irre- 

 gularities appear mostly to have been produced by faults. Those 

 faults on the north shore show change of level of the zone, by dis- 

 location, where parts are separated, and thrown up or down from ad- 

 joining parts. At Whitepark, near Ballintoy, the whole body of the 



