Geological Relations of the East of Ireland . 
155 
Western Division . 
§ 39. On the western side of the granite region, the mica slate 
forms a variously curved line from its northern extremity, near 
Rathfarnham, to its southern in the parallel of Baltinglass ; and the 
most interesting relations of this tract are to be found at these 
extreme points. In the northern, the line passes to the south of 
Montpelier-hill, crosses Glenismaule in an oblique direction, and 
occupies the upper part of the hollow which separates Seefiniane 
mountain on the east, from Seechon on the west ; (see Plate 9. 
No. 10.) This hollow is furrowed both on the north and south 
side by a ravine, an examination of which presents some curious 
facts. 
§ 40. In following the northern ravine from Glenismaule 
upward, we meet with granite rock alone for about three-fohrths 
of the ascent, when mica slate appears in contact with and resting 
upon the granite ; the strata standing nearly on their edges, ranging 
north-east and south-west, and dipping 75° to the north-west. In 
this spot, which is about one hundred yards above the first water- 
fall encountered in our progress, the granite exhibits some disposi- 
tion toward the structure of gneiss, but to a small extent only. At 
the second waterfall, the mica slate is better exposed, ranging here 
east and west, and dipping 7 5° north. It contains some thin layers 
of quartz, sometimes pure, sometimes mixed in part with felspar. 
Considerably higher up the rock ranges 25° north of east and 
south of west, dipping as before. Beyond this occurs a bed of 
small grained granite in the mica slate, about six inches wide, the 
range and dip being the same as last observed ; and within a few 
inches of this first bed of granite is a second of the same width, 
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