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.
These bedded rocks are associated with dark coloured traps and diabase, which are present in the form of sills between the bedding; as dikes cutting the bedded rocks and as large intrusive masses. Dr. Sutherland classified these rocks as the equivalents of the Tertiary sandstones of Disko on account of their lithological resemblance and from the occurrence of traps with both. The southern junction of these bedded rocks with the granites and gneisses forming the Greenland coast to the southward was not seen, but at Foulke fiord and at Cape Isabella the northern contact is quite plain. In both places the bedded series, for some considerable distance from the contact, has been tilted and fractured, while near the contact the sandstones and limestones appear to have been changed into quartzite and crystalline limestones by the injection of great masses of granite. This granite seen at Cape Sabine and Cape Herschel is an ordinary Laurentian granite, and in no way resembles the acidic rocks of Tertiary or Post-Tertiary age, which they should do if the bedded series were of the age assigned to them by Dr. Sutherland. The sandstones, limestones and their associated traps bear a close resemblance to portions of the Huronian series found on Hudson bay and in the interior of Labrador. There is also a similarity between their contacts with the Laurentian granite and some of the contacts found in those more southern localities. No fossils have as yet been found in these rocks, and until such are found it is thought best to remove this series from the Tertiary and place it in the Huronian.
On the past voyage the coast of Ellesmere island was lost sight of about twenty miles south of Cape Isabella, and no land was again seen on the west side of Baffin bay until Philpots island, lying off the east end of North Devon, was reached, where the ship passed sufficiently close to the small outlying islands to show that they were composed of Laurentian gneisses and granites. From thence similar rocks were seen forming the southern shores of North Devon as far as the west side of Croker bay, where they begin to sink slowly to the westward, and are capped by a considerable thickness of flat-bedded limestone, which rests unconformably upon the rounded surface of the older rocks. The Laurentian rocks finally dip below the sea a few miles to the westward of Cuming creek.
The specimens from the Laurentian area, which extends southward from Hayes sound to Cape Isabella, were collected at Capes Sabine and Herschel. The specimens from both localities are very similar, the prevailing rock being a moderately coarse-grained granite, of a dark-red colour, composed largely of red feldspar and bluish quartz, with a small quantity of biotite in diminutive scales. These rocks are only slightly foliated in a few places.
The specimens from the Laurentian measures beneath the Silurian limestones at Cuming creek show a greater variety. A red gneiss, varying in texture from fine to coarse, predominates. It is composed largely of feldspar, with quartz and considerable biotite. It cuts a lighter-coloured, more quartzose gneiss, and also bands of dark mica-diorite-gneiss.
Scottish Whalers in Ponds Inlet.