This group contains the large islands of Bank, Victoria, Prince of Wales, North Somerset and King William, all situated south of Lancaster sound and west of Prince Regent inlet. North Somerset alone was visited by the Neptune; all geological information concerning the others being from the observations made by the several parties engaged in the search for the Franklin expedition.
Dr. G. M. Dawson collected this information from the narratives of these search expeditions, and printed a concise summary of it in his report on the northern portions of the Dominion, from which the following notes have been taken:—
‘Archæan rocks are found only on Prince of Wales and North Somerset islands, where a spur from the great mass of crystalline rocks forming the northeastern mainland extends northward through the peninsula of Boothia and forms the land on both sides of Peel sound.
‘The granitoid rocks are again found on the west side of North Somerset, where they form the eastern boundary of Peel sound. Boulders of the granite are found at a considerable distance (100 miles) to the northeastward of the rock in situ, as at Port Leopold, Cape Rennell, &c. The general characters of the granitic rocks in the north and west of North Somerset are thus described by Capt. M’Clintock: “Near Cape Rennell we passed a very remarkable rounded boulder of gneiss or granite; it was six yards in circumference, and stood near the beach, and some fifteen or twenty yards above it; one or two masses of rounded gneiss, although very much smaller, had arrested our attention at Port Leopold, as then we knew of no such formation nearer than Cape Warrender, 130 miles to the northeast; subsequently we found it to commence in situ at Cape Granite, nearly 100 miles to the southwest of Port Leopold. The granite of Cape Warrender differs considerably from that of North Somerset, the former being a graphic granite, composed of gray quartz and white feldspar, the quartz predominating, while the latter, a North Somerset granite, is composed of gray quartz, red feldspar and green chloritic mica, the latter in large flakes. Both the granite and gneiss of North Somerset are remarkable for their soapy feel.’
‘To the east of Cape Bunny, where the Silurian limestone ceases, and south of which the granite commences, is a remarkable valley called Transition valley, from the junction of sandstone and limestone that takes place there. The sandstone is red, and of the same general character as that which rests upon the granitoid rocks of Cape Warrender and at Wolstenholm sound. Owing to the mode of travelling, by sledge on the ice, round the coast, no information was obtained of the geology of the interior of the country, but it appears highly probable that the granite of North Somerset, as well as that of the other localities mentioned, is overlaid by a group of sandstones and conglomerates, on which the Upper Silurian limestones repose directly. A low sandy beach marks the termination of the valley to the northward, and on this beach were found numerous pebbles, washed from the hills of the interior, composed of quartzose sandstone, carnelian and Silurian limestone.’
‘Cape Granite is the northern boundary of the granite, which retains the same character as far as Howe harbour. It is composed of quartz, red feldspar and dark-green chlorite, and is accompanied with gneiss of the same composition.’
‘The granitoid rocks extend across Peel sound into Prince of Wales island in the form of a dark syenite, composed of quartz, greenish-white feldspar passing into yellow, and hornblende.’
ISLANDS OF GROUP IV.
Archæan rocks are found only in the eastern part of this group, on the large islands of Ellesmere and North Devon. They rise from beneath the newer rocks on the south side of Hayes sound a few miles north of Cape Sabine, and then occupy the remainder of the eastern coast of Ellesmere and that of North Devon. This area appears to form a wedge-shaped mass expanding southward, so that on Jones and Lancaster sounds they extend a considerable distance to the westward, until they become capped by limestone, and then gradually sink below the level of the sea.
Both the Laurentian and Huronian divisions of the Archæan are represented in the area. A series of bedded rocks consisting of several thousand feet of sandstones, limestones and other sediments occupies the coast and islands of the east side of Smith sound, from Cape Atholl northward to Foulke fiord. On the west side the northern limit of these rocks is Cape Isabella, from which they occupy the shore of Ellesmere for upwards of twenty miles to the south, the southern limit not having yet been determined on that side.