402 
THE TERTIARY VOLCANOES 
BOOK VIII 
h-Iolaire (Eagle’s Crag), and thence up into the great gabbro ridge of Ben 
Buy. From the main body of granophyre a multitude of veins ascends 
through the basalts and gabbros from two feet or more in breadth down to 
mere filaments (Fig. 358). Even at a height of 800 feet up the hill some 
of these veins are still three inches broad, and present the usual granophyric 
Fig. 358. — Mass of dark gabbro about two feet iu diameter traversed by pale veins of granopliyre, 
lying on north slope of Creag na li-lolaire, Mull. 
structure, though rather finer in grain than the general mass of the boss, 
and sometimes assuming a compact felsitic and spherulitic texture at the 
immediate contact with the surrounding rock. One of the most striking 
proofs of the posteriority of these veins is furnished by the perfect flow'- 
Fig. 359. — Section at Creag 11 a h-Iolaire, Glen More, Mull, showing basalts and gabbros 
resting on and pierced by granophyre. 
a, much indurated and altered basalts and dolerites ; b b, gabbro ; c, granophyre ; d d, basalt dykes. 
structure they not infrequently exhibit along their margins, their long 
felspar crystals being arranged parallel to the walls in lines that follow the 
sinuosities of the boundary between the two rocks. Patches of gabbro 
and of the indurated basalts may he seen lying on the granophyre, from 
which veins and strings ramify through them (Fig. 359). Similar veins 
