151 
Geological Relations of the East of Treland. 
mine. Again, several beds still lower are to be observed in two 
ravines, situated higher up in the glen to the north-west, in the 
farthest of which, (on the townland of Cullentrough,) we come to 
the fundamental granite, which, thence forward, occupies the bot- 
tom and brows of the glen ; but the outgoings of the alternating 
beds to the north-west, may still be occasionally traced a consider- 
able way up, in the precipices above. 
From the whole of these data, I compute the thickness of these 
alternations to be about one-third of a mile, measuring at right 
angles with the dip. In their north-eastern termination, they pro- 
bably abut upon the granite nucleus, being hid toward the Glen- 
dalough side by the great mass of mica slate which rests upon 
them, and which constitutes the ridge and eastern portion of Lug- 
duff. In their progress to the south-west, they traverse Glenmalur, 
but their relations on the southern face of the glen are not easily 
developed, the slope being greatly encumbered with debris. They 
occupy however only a small district ; as the continuous body of 
mica slate is inflected more towards the south in the upper part of 
the range, that divides Glenmalur from Aughavanagh. 
§ 34. In descending Glenmalur, mica slate continues on either 
hand to the barracks at the lower part, and is often curiously incur- 
vated and contorted ; the fragments sometimes much resembling 
splinters of wood. It contains frequent beds of quartz, from a few 
inches to three feet in thickness, which may be distinctly observed 
in ascending the military road from the barracks toward Drumgoff 
hill, on the south-eastern quarter of which the granite rock re- 
appears for a short space. The military road then passes over 
mica slate until within a mile and a quarter of Aughavanagh bar- 
racks, when the fundamental granite becomes again visible, occu- 
pying the whole basin of Aughavanagh, and the brows of the sur- 
rounding mountains. 
