137 
Geological Relations of the East of Ireland . 
vation, from one thousand to twelve hundred yards in width, and in 
length between two and three miles, with precipices arising on either 
hand, from eight hundred to one thousand feet in height. At the 
head of the glen, the granite forms mural precipices, and here, in 
the waterfall, in the bed of the stream above it, and in the high 
granite rocks on the north side, we perceive numerous contempora- 
neous veins of granite and quartz, several of which range parallel to 
each other in a north and south direction, while these are frequently 
crossed under various angles by others, which sometimes produce a 
heave or throw in the traversed veins. They sometimes occur so 
numerously in a narrow compass, as almost to resemble a kind of 
net work. The position of these veins is generally vertical ; but in 
the granite rocks above Glenasane, on the line toward Luganure 
lead mine, I have observed veins of quartz in the granite rock in a 
nearly horizontal position; and the same occurrence may be remarked 
also on the Dalkey coast. 
§ 20. The granite precipices at the head of Glendalough present 
no mark of stratification : they are variously and irregularly divided 
by cross fissures ; and from the cliffs above have been detached from 
time to time vast blocks and masses, some of the magnitude of a 
cottage, which form in accumulated heaps a kind of rude shelving 
slope, ascending from the valley toward the firm rocks above, to the 
height of three hundred, four hundred, and five hundred feet. 
Is granite stratified? — Is a question which has been repeatedly 
agitated. An attentive examination of the granite region, now 
under consideration, particularly where a considerable denuded sur- 
face is exposed, as in the bold precipices of the upper and lower 
Lough Bray, Balreagh glen, Lough Tay, Loughnahanagan, Glenda- 
lough, Glenmalur, and the abrupt sides of Lugnaquilla, leads me to 
conclude that the interior granite nucleus, or that which constitutes 
Vol. V. 
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