1873.] CAMPBELL GLACIATION OF IRELAND. 201 



hill, are the edges of beds of chalk covered by basalt, which corre- 

 spond to beds at distant points which may be seen from the hill- top 

 as in a geological model. The chalk formation here is thinner, and 

 it dips northwards at a low angle. It crops out at the sea-coast, in 

 Lough Foyle, northwards, in Belfast Lough, at Fairhead, and all 

 round a great solitary dome-shaped mountain, Slieve Lude, which 

 rises above Ballycastle. At Slieve Gallion these newer beds rest 

 unconformably upon the edges of older beds, as they do forty miles 

 away at Cushendal. There is nothing in the present surface-forms 

 of these hills to indicate their structure. The chalk and basalts, 

 and the older rocks upon whose edges they were poured out and 

 deposited flat, have been worn away together over a large area in 

 this region for a depth equal to the height of hills at opposite sides 

 and ends of Lough Neagh. The " cap " on the top of Slieve 

 Gallion is a remnant of a great sheet about forty miles square at 

 least ; and rock taken away from hollows since the basalt formed was 

 about 2000 feet deep. 



Near the southern end of Lough Neagh and near Dnngannon and 

 Cookstown, the rock-surface is laid bare in quarries. The edges of 

 sandstone beds of the coal-formation are crushed and shattered. 

 Fragments are close to the rock, up in the Boulder-clay, which caps 

 the quarry, together with hard smooth grooved boulders of granite 

 and metamorphic rocks. These last abound at Cookstown, between 

 Slieve Gallion and Dungannon. On the slopes of Slieve Gallion 

 they rise to a height of about 1200 feet. In the low country the 

 drift is packed in long high ridges. Some of the stones came from 

 a distance ; for there is nothing like them in the coal-field. 



Southwards, near Armagh, and on the shores of Carlingford 

 Lough, I found scratched polished flints and angular flints, amongst 

 debris of the coal-formation, and basalts, and far older rocks. Ac- 

 cording to other observers, quoted by Mr. Close, " Antrim Flints " 

 are found in gravels about Bray, near Dublin, and even as far south 

 as Waterford; Mr. Froude brought me flints from Bray. These 

 flints travelled southwards, and did not go northwards. I could 

 find no flints or chalk north of Donegal Bay and Lough Swilly. 

 About 2000 feet of basalt and chalk, of coal-measures, and of older 

 rocks, upon which they were deposited, certainly were crushed, and 

 broken and ground off an area of more than forty miles square- 

 about Lough Neagh, between Lough Foyle and Belfast Lough, Slieve 

 Gallion and Fairhead. 



Along the sea-coast between Fairhead and Lame, the sea is 

 grinding rocks at the sea-level so as to bring chalk and flints 

 to one polished surface. At a higher level the sea has made a 

 series of caves which can be seen from the road. The same 

 engine has undermined promontories, so that masses have fallen 

 leaving cliffs with talus heaps, and cliffs from which the talus has 

 been removed. In these cliffs the same forms are repeated all the 

 way from Larne to Lough Foyle. They may coincide with faults ; 

 but I could find no faults coinciding with the coast. 



Within this area arc the marks of two great " denuding engines." 



