70 Mr. Bryce on the Geological Structure of 



Ben-cruachan about .1500. From the main body of the chain project, in 

 the southern part of the district, several long ridges, with flat, broad summits 

 and precipitous sides. They reach almost to the sea-shore, and are separated 

 by deep and narrow glens, which extend far into the interior; the principal 

 being GlenarifF, Glenaan, and Glendun. Through these glens flow rivers 

 of the same name; the waters of which are scanty in summer, but in winter 

 are swelled by many tributaries, from the upland bogs ; and tumbling over 

 the cliffs, excavate deep and wide channels, which present to the geologist 

 perfect sections of the strata. 



In the northern part of the district, or that which has Glendun for its 

 southern boundary, the surface of the country is occupied, at intervals, by 

 considerable hills, which are detached from the main chain and from one 

 another, but have a northerly direction, parallel to the principal chain. 

 Those which deserve mention are Glenmackeeran, 1321 feet; Ballypatrick and 

 Brishadhu, about 1100; and Carnanmore and Carnlea, 1250 each. They 

 are of an elongated, narrow form, and in general slope gradually; but the 

 eastern sides of those next the sea, shelve down to the shore in abrupt and 

 rugged terraces. 



The direction of these hills determines that of the valleys and river courses. 

 The valleys have a north and south direction, and open into a principal one 

 running east and west to the south of the elevated ridge which forms the 

 coast from Fair Head to Ballycastle. The rivers flowing through these vafleys 

 turn westward, and pour their united waters into the sea at Ballycastle. 



On the western part of the district, the principal chain of mountain descends, 

 in a succession of undulating hills, into the low country, which extends at their 

 base from Corkey by Armoy to Ballycastle. 



(3.) The following are the principal formations which occur in the district : 

 mica slate, old red sandstone, porphyry, carboniferous limestone, coal with its 

 accompanying strata, new red sandstone and conglomerate, lias, mulatto, chalk, 

 and trap. Granite, primitive limestone, and porphyry occur as subordinate 

 rocks. 



Mica Slate. 



(4.) This formation in the north-east of Antrim, does not vary from its ordi- 

 nary character in the North of Ireland, as described by Dr. Berger. It occa- 

 sionally passes into gneiss, and by the insulation of the crystals of felspar 

 assumes a porphyritic aspect. It contains crystals of quartz and, rarely, of 

 common schorl, also amorphous quartz, accompanied by chlorite. 



Mica slate occupies the greater part of the area under consideration. Its boundary in the south- 

 eastern part of the district is a line ranging, in an irregular north-east direction, from the eastern 



