REPORT ON THE PETROLOGY OF OCEANIC ISLANDS. 127 



describing the rocks of tins fjord, we may consider those from Prince of Wales Foreland, 

 a long and mountainous promontory which stretches from the peninsula already de- 

 scribed towards the entrance of Royal Sound ; the northern boundary is Shoal Water 

 Bay. According to Mr. Buchanan this high promontory is formed of columnar basalt, 

 in some places weathering into spheroids. The rock contains large nodules of olivine. 

 Flat-topped hills extend into the interior beyond this tongue of land with its serrated 

 rocks. They in turn are of basaltic nature, and contain much olivine, but the columnar 

 structure gives place to a bedded arrangement, which in some cases is schistoid. 



Besides the basalts reported by Mr. Buchanan, we have found amongst the speci- 

 mens from this locality a limburgite, a lithological type we have not yet noticed as 

 occurring in the island. Externally it resembles a basalt, but the mass is more shining 

 and bluish black in colour. Bottle-green grains of olivine are visible to the unaided 

 eye ; with the lens smaller crystals of augite become visible. Large sections of brownish 

 olivine appear in the homogeneous vitreous ground-mass. As a rule they have sharp 

 crystallographic outlines, sometimes, however, they are corroded ; they present no 

 peculiarity, except for some large transparent inclusions of chestnut-brown chromite. 

 Augite occurs as well-developed light green crystals, showing distinct outlines, and 

 often twinned polysynthetically. Numerous augite microliths, usually very elongated, 

 occur in the ground-mass. Magnetite is abundant in the form of regular sections, but 

 no felspar is to be seen. The cavities of the rock are lined with fibro-radial zeolites. 



On doubling Prince of Wales Foreland one enters the great bay of Royal Sound, 

 studded with islands and reefs to the number of more than a hundred. The gulf is 

 wide and deep. All the islets and the hills of the neighbouring land terminate in 

 tabular summits. The rocks forming islands in this fjord are strewn with erratic blocks, 

 the number of these ice-borne fragments seeming to increase as we approach the bottom 

 of the bay. The hills are the same as those of Betsy Cove ; in fact, if the great valley 

 there were filled by the sea, the numerous hills of the northern part would appear as 

 islets, and give to the bay the appearance of Royal Sound in miniature. It is almost 

 certain that all the islets and reefs were connected to begin with, forming part of a sheet 

 of lava which descended with a slight slope from the land to the sea. The slope was 

 covered by a great glacier shut in by the hills which now border the sound on the south 

 and north. After having planed down the whole surface over which it flowed, the 

 glacier hollowed out the deep channels between the harder rocks, that now form 

 islands in the bay. During this glacial period, or at some subsequent time, all these 

 islands were covered by the sea in consequence of subsidence ; the icebergs, broken off 

 from the glacier as it entered the sea, deposited the erratic blocks upon the summits of 

 the islets of the Sound. At this time, also, moraines must have been carried away. 



Hog Island is the only one in Royal Sound the rocks of which are known. Specimens 



