152 
Mr. Weaver on the 
The junction of the granite and mica slate may be distinctly seen 
in a ravine, which marks the northern face of Croghan Moira, 
the water from which is conducted under the military road. At this 
spot we may observe that the granite acquires more and more of a 
quartzy nature as it approaches the mica slate, becoming almost slaty 
quartz at the point of contact ; while the mica slate itself abounds in 
beds of quartz of variable thickness, and the granite is traversed in 
all directions by contemporaneous veins of quartz of greater or less 
magnitude, and also by veins of granite. The mica slate, from this 
place, pursues its course to the northward over the mountains to- 
ward Glenmalur, forming the western border before alluded to, but 
in its progress to the south it passes in a south-west direction 
through the western arm of Croghan Moira, (called Muckla,) and 
crossing Aughavanagh river, penetrates Ballygobben mountain ; the 
line of junction on both sides of the river being visible to the eye. 
§ 35. From the position I have just mentioned, we perceive to 
the north-west Lugnaquilla, rising with its bold granite precipices 
above Aughavanagh, and capped with mica slate, which occupies its 
summit and a considerable part of its western declivity ; while the 
steep brows around the mountain, its precipitous sides toward Glen- 
malur on the east, and toward the glen of Imale on the north, and 
its long southern arm, consist of granite. These precipices on the 
south side are called the South Prison, as corresponding precipices on 
the opposite side are called the North Prison, in both instances con- 
stituting a nook or recess in the mountain, in which the eastern 
border of the cap of mica slate may be observed reposing upon the 
granite. The summit of this mountain forms a kind of table land, 
presenting a smooth green sod and fine sheep pasture, and is strongly 
contrasted with many of its neighbours, and indeed with its own 
flanks, which partake more of the general character of peaty soil, 
