52 REPORT—1863. 
true granite ; but when seen in the field, it is found to be stratified, the strike 
of the beds agreeing with that of the uncontorted sedimentary strata of the 
country, and the dip being nearly constant in amount, and uniformly to the 
eastward. In addition to these granitic beds there are numerous others 
(which become more abundant as you approach the edge of the district) which 
would be pronounced gneiss even from an examination of hand-specimens. 
This fact, which has been abundantly confirmed by observations in various 
localities, places the gneissose character of the rock, as a whole, beyond a 
doubt. The gneiss on the eastern cdge of the granite, especially near 
Fintown and near Trawenagh Bay, is remarkable for the extraordinary 
development of crystallized orthoclase, of a red colour, which is to be seen in 
it, giving it an appearance very similar to that of the feldspar-veins at Castle 
Caldwell, which will be mentioned further on. 
As a further illustration of the gneissose character of the granite, we may 
draw attention to the fact that, in numerous localities, portions of highly 
contorted gneiss are found actually within the granite. ‘his is the case at 
Bunbeg, Lough Anure, Annagary, at the head of Glenveagh, above Gartan 
Abbey, at Toberkeen, Lough Pollrory, near Trawenagh Bay, Glenleheen, and 
near Lough Errig. These fragments of gneiss are sometimes of slight extent ; 
sometimes, as at Lough Errig, they extend for 40 or 50 yards. Such an 
appearance as this is usually accompanied by the presence in the granite of 
highly crystalline limestones. . These occur at the head of Glenyeagh, again 
under Altahostia, halfway down the lake, at Glenveagh Bridge, and at the 
Gap of Barmesbeg. At Glenleheen we found that the limestone occurred in 
four distinct beds, possessing a strike of E. 5° N., which is coincident with that 
obtained from the rocks at Lackagh Bridge. The appearance in each locality 
is not absolutely continuous ; but their identity of strike in different localities 
points to the existence of four distinct parallel beds. The three deposits of 
limestone in Glenveagh probably belong to the same bed, of which the con- 
tinuity has been interrupted. 
It is worthy of notice that this occurrence of non-granitie rocks in the 
granite is not strictly confined to the district where the texture of the rock is 
most decidedly gneissose, as in some of the localities (such as Toberkeen, 
Annagary, and Lough Anure) the limestone is found in contact with very 
coarse-grained granite. However, in this district there is ajseries of small 
patches of limestone extending in a curved line from Bunbeg towards Crohy 
Head and apparently bounding the district of Dunglow, in which the coarse- 
grained granite occurs. 
In illustration of this relation of the rocks to each other I may again quote 
Mr. MacFarlane, who says, after giving a synopsis of the rocks to be met 
with in the Primitive Gneiss of Norway, which he compares to the Laurentian 
Series of Canada :— 
‘«« As to the mode in which these rocks are associated with each other, the 
whole of them are arranged in parallel layers or zones, side by side, under- 
lying or else overlying each other. Hitherto no regular succession of rocks 
has been marked; they appear to be interstratified with each other without 
rule. The granitic masses are partly conformable with the parallel masses of 
the schistose rocks, and partly occur irregularly. It has been remarked that, 
when the granite becomes more or less gneissoid, its masses are regularly 
interstratified with the other schistose rocks; but where the granite is totally 
free from all traces of gneissoid texture, the form in which it occurs deviates 
more or less from that of layers or beds. A remarkable instance of this is 
described by Keilhau as occurring near Norefield*, There he saw a mass of 
