Reports and Proceedings— Geological Society of London. 135 
RAPORDTS AND PROCHHDINGS.- 
GrotogicaL Society or Lonpon. 
J.—January 25th, 1893.—W. H. Hudleston, Esq., M.A., F.B.S., 
President, in the Chair. The following communications were read :— 
1. “On Inclusions of Tertiary Granite in the Gabbro of the 
Cuilin Hills, Skye; and on the Products resulting from the Partial 
Fusion of the Acid by the Basic Rock.” By Prof. J. W. Judd, 
F.R.S., V.P.G.S. 
The author first calls attention to previous literature bearing 
on the subject of the extreme metamorphism of fragments of one 
igneous rock which have been caught up and enveloped in the 
products of a later eruption. The observations of Fischer, Lehmann, 
Phillips, Werveke, Sandberger, Lacroix, Hussak, Graeff, Bonney, 
Sauer, and others show that, while the porphyritic crystals of such 
altered rocks exhibit characteristic modifications, the fused ground- 
mass may have developed in it striking spherulitic structures. 
On the north-east side of Loch Coruiskh, in Skye, there may be 
seen on a ridge known as Druim-an-Hidhne, which rises to a little 
over 1000 feet above the sea, a very interesting junction of the 
granitic rocks of the Red Mountains with the gabbros of the Cuilin 
Hills. At this place, inclusions of the granitic rock, sometimes 
having an area of several square yards, are found to be completely 
enveloped in the mass of gabbro. The basic rock here exhibits 
all its ordinary characters, being a gabbro passing into a norite, 
traversed by numerous segregation veins; the acid rock is an 
augite-granite, exhibiting the micropegmatitic (“‘granophyric”’) and 
the drusy (‘“miarolitic”’) structures, and it passes in places into an 
ordinary quartz-felsite (‘‘ quartz-porphyry ”’). 
Within the inclusions, however, the acid rock is seen to have 
undergone great alteration from partial fusion, and it has acquired 
the compact texture and splintery fracture of a rhyolite; weathered 
surfaces of this rock are found to exhibit the most remarkable 
banded and spherulitic structures. 
Microscopic study of the rock of these inclusions shows that the 
phenocrysts of quartz and felspar remain intact, but exhibit all the 
well-known effects of the action of a molten glassy magma upon 
them. The pyroxene, however, has been more profoundly affected, 
and has broken up into magnetite and other secondary minerals. 
The micropegmatitic ground-mass, which was the last portion of 
the rock to consolidate, has for the most part been completely fused, 
and in some places has actually flowed. In the glassy mass thus 
formed, the most beautiful spherulitic growths have been developed, 
the individual spherulites varying in size from a pin’s head to a 
small orange. ‘These spherulites are often composite in character, 
consisting of minute examples of the common type enclosed in larger 
arborescent growths (‘ porous-spherulites”’) of felspar microlites, 
with silica, originally in the form of opal and tridymite, but now 
converted into quartz, lying between them. All the interesting 
forms of spherulitic growth which have been so well described by 
