“On the upper portion of Ferguson river Laurentian rocks prevail and similar granites and gneisses occur along the north shore of Baker lake, and down both shores of Chesterfield inlet to its mouth, whence they extend southward along the shore of Hudson bay to a short distance north of Baker’s foreland. Any information which we possess about geology of Great Fish river and Coppermine river would seem to show that the Laurentian granites and gneisses outcrop with greater or less frequency along their banks, so that we may safely infer that the Barren Lands are largely underlain by these ancient igneous rocks, and consequently there are large areas which will not produce valuable minerals.
“But as farther south we find quartzite, greywackes, and highly altered eruptive rocks of Huronian age, folded in here and there with typical Laurentian rocks, so in the far north we may confidently expect to find the same set of conditions prevailing.
“Such is to be found the case in the country lately examined immediately west of Hudson bay, where several areas of Huronian rocks, precisely similar to
Those Found at Sudbury,
Lake of the Woods, and at many places around Lakes Huron and Superior, have been discovered. The largest of these areas extends more or less continuously for one hundred and twenty miles along the west coast of Hudson bay, from near Baker’s foreland to a point forty-five miles north of Cape Eskimo, and from the bay shore for seventy miles inland on the course of Ferguson river. A smaller area crosses Dubawnt river between Schultz and Baker lakes, a third occurs on the Kazan river below Angikuni lake, a fourth was recognized in the basin of Ennadai lake.
“Two more areas are represented by outcrops of white clastic quartzite on the north shore of Dubawnt lake, and on the east shore of Wharton lake.
“The rocks constituting the system in this region have been divided into three more or less distinct groups, viz: Marble island quartzites; the greenish quartzites and greywackes; and the more or less highly altered and often schistose diabases and gabbros.
“The Marble island quartzites are composed of hard white quartzite, consisting of more or less rounded grains of quartz, of fairly regular size, cemented together by interstitial silica. They are distinctly stratified in thick and thin beds, and the surfaces of the beds are often covered with beautiful ripple-markings. The thicker beds also often show distinct false bedding. They are usually in a more or less inclined position, but they were nowhere seen to be very much crumpled or squeezed into minute folds. These quartzites on the north shore of Quartzite lake dip regularly northwestward, away from a hill of diabase which lies to the south, and the latter therefore probably underlies the quartzite, though it is not necessarily older than it. In other places very little evidence was obtained of the relative ages of the white quartzite and the other parts of the Huronian. However, it would seem probable that, in the region near the shore of Hudson bay, this quartzite is
The Oldest Part of the Huronian,
and that the diabases, and other basic eruptions which are associated with it, have been intruded beneath it, and have also flowed over it. That Marble island quartzites were once spread over a large portion of the region under consideration is shown, not so much by the few scattered outlines here mentioned, as by the fact that the overlying Cambrian conglomerates, which cover large areas between Dubawnt and Baker lakes, are composed chiefly of pebbles of this white quartzite.