6o Guide to Belfast. 



as at Glenarm and the White Rocks, near Portrush. In 

 places, I ,ias underHes the Chalk ; and as the Lias is semi- 

 plastic in certain localities, as at Carnlough and Garron, it 

 produces its effects on the landscape by causing numerous 

 landslips. It is only in such slipped masses that the dip of 

 the strata deviates much from the horizontal. 



To this general statement there are, of course, exceptions. 

 Numerous natural causes have been at work since the 

 deposition of the basalt of the Eocene times to modify 

 and mask the " plateau " character of the inland districts 

 of Antrim, or to modify the regularity of outline of the 

 basalt escarpment. The course of river development may 

 be studied in the romantic and picturesque Glens of Antrim 

 to the greatest advantage : there we find many examples 

 which might serve as text-book illustrations of the progress 

 and "life history of rivers," from the steep and rapid 

 torrents that pour as waterfalls over the edge of the basalt 

 escarpment to the older types which have eaten back their 

 courses far into the basalt plateau 



Again, on the western side of the county are to be found 

 slow and meandering rivers winding among the glacial sands 

 and gravels that cover the basalt plateau, finding an outlet 

 sometimes in Lough Neagh, like the river Main, the Six- 

 mile Water, and the Glenavy river ; or, like the Lower Bann, 

 flowing into the open sea with a fall of 48 feet in a course 

 of 35 miles. 



County Down. — The county of Down consists, on the 

 other hand, chiefly of rocks of the Ordovician era ; the 

 strata are much contorted by the great earth movements of 

 post-Silurian times, so that it is difficult and often impossible 

 to follow any given bed over any great area, or to draw a 

 sharp dividing line between two beds of different ages. In 

 a few places rocks of a later age occur, as in the Comber 

 river valley, where Triassic rocks are to be found capped 

 by a sheet of basalt, an outlier of the Antrim plateau ; but 

 these rocks still retain their original horizontality, and occupy 

 a small area. 



In the centre and in the south of the county are to be 

 found two districts of mountainous character. Between 

 Dromara and Castlewellan is found an outcrop of granite 



