Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/655

1870.] HIND — GNEISSOID SERIES OF NOVA SCOTIA. 473 Brunswick Reporf as occurring on the Nipisiquit, and near Dumbarton station, on the New Brunswick and Canada railroad (pp. 147 and 154), where they are associated with the red slates supposed to be the uppermost member of the Quebec group of Sir W. E. Logan. The black corrugated slates contain conformable auriferous beds of quartz ; but no mining is at present carried on in these deposits. They are about 3000 feet in thickness, and are conformably underlain by the gold-bearing rocks.

The Gold-bearing Rocks. — The known gold-bearing rocks of Nova Scotia consist of quartzites, sandstones, and grits, interstratified with argillaceous slates, and thin conformable beds and intercalated beds of auriferous quartz. The portion has an ascertained thickness exceeding 9000 feet ; and between the base and a vertical thickness of about 3000 feet from the summit, the thin beds of quartz yielding gold are found, and are worked in different districts in this Province, so that a mass of strata having a thickness of 6000 feet, or more than a mile, yields gold from quartz-beds of contemporaneous age with the quartzites and slates with which they are interstratified ; and it is from these quartz-beds that the greater part of the gold of Nova Scotia is obtained*. The total thickness of the gold-bearing series, including the corrugated black slates and the brilliant micaceous schists, is about 12,000 feet.

IV. The Cambrian, or Huronian Series.

In some parts of Nova Scotia the known gold-bearing rocks rest unconformably on a gneissoid series, well exposed to view on the Halifax and Windsor Railway, between the Stillwater and Mount Uniacke Stations (Pl. XXX. fig. l), and near the village of Sherbrooke, in Guysborough County (fig. 4). This series is composed of beds of gneiss, interstratified with micaceous schists, schist conglomerate, beds of true quartzite, and grits. The gneiss is sometimes porphyritic ; and the upper beds are almost always conglomerate, holding pebbles and masses of schist, grits, and conglomerates, which are found in this series. Some of the gneissic strata are granatiferous, as are also the micaceous schists. Between Stillwater and Mount Uniacke Stations the general strike of the Lower Silurian is N. 80° E., dip N. 80°; the prevailing strike of the Huronian is S. 50° E., the railroad-track running for two or three miles on the strike of these rocks. Near to their junction with the Huronian, the Silurian strata are more altered than where remote from them, and hold numerous crystals of andalusite. This series has been very extensively denuded, and in some places Silurian, Huronian, and Laurentian are seen in close juxtaposition. The thickness at Sherbrooke is about 1300 feet.

When the preliminary Report already referred to was in the hands of the printer, I satisfied myself, by repeated observations, that a very decided unconformability existed between these supposed older strata and the gold-bearing series, also between the older

lodes, distinguishing between contemporaneous and intercalated lodes.
 * Vide my Report on the Sherbrooke Gold-District for a description of the auriferous

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